10-Q

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q

(Mark One)

x QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended June 30, 2016

OR

¨ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from                      to                     

Commission file number: 001-36167

Karyopharm Therapeutics Inc.

(Exact name of registrant as specified in its charter)

Delaware	26-3931704
(State or other jurisdiction of incorporation or organization)	(I.R.S. Employer Identification Number)
85 Wells Avenue, 2nd Floor Newton, MA	02459
(Address of principal executive offices)	(Zip Code)

(617) 658-0600

(Registrant’s telephone number, including area code)

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    Yes  x    No  ¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    Yes  x    No  ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer	¨	Accelerated filer	x
Non-accelerated filer	¨ (Do not check if a smaller reporting company)	Smaller reporting company	¨

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).    Yes  ¨    No  x

As of July 31, 2016 there were 35,989,260 shares of Common Stock, $0.0001 par value per share, outstanding.

TABLE OF CONTENTS

	PART I—FINANCIAL INFORMATION
Item 1.	Condensed Consolidated Financial Statements (Unaudited)	3
	Condensed Consolidated Balance Sheets	3
	Condensed Consolidated Statements of Operations	4
	Condensed Consolidated Statements of Comprehensive Loss	5
	Condensed Consolidated Statements of Cash Flows	6
	Notes to Condensed Consolidated Financial Statements	7
Item 2.	Management’s Discussion and Analysis of Financial Condition and Results of Operations	13
Item 3.	Quantitative and Qualitative Disclosures About Market Risk	18
Item 4.	Controls and Procedures	18
	PART II—OTHER INFORMATION
Item 1A.	Risk Factors	19
Item 6.	Exhibits	49
	Signatures	50

PART I—FINANCIAL INFORMATION

Item 1. Condensed Consolidated Financial Statements (Unaudited).

Karyopharm Therapeutics Inc.

CONDENSED CONSOLIDATED BALANCE SHEETS

(unaudited)

(in thousands, except share and per share amounts)

	June 30, 2016			December 31, 2015
Assets
Current assets:
Cash and cash equivalents	$	37,717		$	58,358
Short-term investments		85,019			117,275
Prepaid expenses and other current assets		1,464			1,967
Total current assets		124,200			177,600
Property and equipment, net		3,170			3,483
Long-term investments		42,933			33,878
Restricted cash		483			482
Other assets		111			—
Total assets	$	170,897		$	215,443
Liabilities and stockholders’ equity
Current liabilities:
Accounts payable	$	4,063		$	3,808
Accrued expenses		11,112			11,023
Deferred rent		269			206
Other current liabilities		79			95
Total current liabilities		15,523			15,132
Deferred rent, net of current portion		1,808			1,946
Total liabilities		17,331			17,078
Stockholders’ equity:
Preferred stock, $0.0001 par value; 5,000,000 shares authorized; none issued and outstanding		—			—
Common stock, $0.0001 par value; 100,000,000 shares authorized; 35,989,260 and 35,864,765 shares issued and outstanding at June 30, 2016 and December 31, 2015, respectively		4			4
Additional paid-in capital		467,168			455,170
Accumulated other comprehensive income (loss)		138			(282	)
Accumulated deficit		(313,744	)		(256,527	)
Total stockholders’ equity		153,566			198,365
Total liabilities and stockholders’ equity	$	170,897		$	215,443

See accompanying notes to condensed consolidated financial statements.

3

Karyopharm Therapeutics Inc.

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS

(unaudited)

(in thousands, except share and per share amounts)

	Three Months Ended, June 30,						Six Months Ended June 30,
	2016			2015			2016			2015
Contract and grant revenue	$	59		$	150		$	59		$	150
Operating expenses:
Research and development		24,579			27,006			46,374			47,757
General and administrative		5,956			6,157			11,510			11,556
Total operating expenses		30,535			33,163			57,884			59,313
Loss from operations		(30,476	)		(33,013	)		(57,825	)		(59,163	)
Other income:
Interest income		329			267			615			408
Other income (expense)		(11	)		51			(7	)		(7	)
Total other income, net		318			318			608			401
Net loss	$	(30,158	)	$	(32,695	)	$	(57,217	)	$	(58,762	)
Net loss per share—basic and diluted	$	(0.84	)	$	(0.92	)	$	(1.59	)	$	(1.65	)
Weighted-average number of common shares outstanding used in net loss per share—basic and diluted		35,956,470			35,697,012			35,917,486			35,508,146

See accompanying notes to condensed consolidated financial statements.

4

Karyopharm Therapeutics Inc.

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS

(unaudited)

(in thousands)

	Three Months Ended June 30,						Six Months Ended June 30,
	2016			2015			2016			2015
Net loss	$	(30,158	)	$	(32,695	)	$	(57,217	)	$	(58,762	)
Comprehensive income (loss)
Unrealized gain (loss) on investments		64			(94	)		407			(42	)
Foreign currency translation adjustments		(20	)		(68	)		13			(73	)
Comprehensive loss	$	(30,114	)	$	(32,857	)	$	(56,797	)	$	(58,877	)

See accompanying notes to condensed consolidated financial statements.

5

Karyopharm Therapeutics Inc.

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(unaudited)

(in thousands)

	Six Months Ended June 30,
	2016			2015
Operating activities
Net loss	$	(57,217	)	$	(58,762	)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization		358			292
Net amortization of premiums and discounts on investments		595			816
Stock-based compensation expense		11,563			8,231
Changes in operating assets and liabilities:
Prepaid expenses and other current assets		503			(2,038	)
Other assets		(89	)		774
Accounts payable		233			(1,782	)
Accrued expenses and other liabilities		70			3,446
Deferred rent		(75	)		699
Net cash used in operating activities		(44,059	)		(48,324	)
Investing activities
Purchases of property and equipment		(45	)		(774	)
Proceeds from maturities of investments		110,046			41,069
Purchases of investments		(87,033	)		(209,517	)
Net cash provided by (used in) investing activities		22,968			(169,222	)
Financing activities
Proceeds from the issuance of common stock, net of issuance costs		—			90,830
Proceeds from the exercise of stock options and shares issued under employee stock purchase plan		436			347
Net cash provided by financing activities		436			91,177
Effect of exchange rate on cash		14			(9	)
Net decrease in cash and cash equivalents		(20,641	)		(126,378	)
Cash and cash equivalents at beginning of period		58,358			150,609
Cash and cash equivalents at end of period	$	37,717		$	24,231
Supplemental disclosure of non-cash financing activity
Property and equipment purchases included in accounts payable and accrued expenses	$	—		$	52
Vesting of restricted common stock	$	—		$	84
Deferred financing costs included in accounts payable	$	22		$	—

See accompanying notes to condensed consolidated financial statements.

6

Karyopharm Therapeutics Inc.

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(in thousands except share and per share data)

1. Summary of Significant Accounting Policies

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements of Karyopharm Therapeutics Inc. (the “Company”) have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial reporting and as required by Regulation S-X, Rule 10-01. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments (including those which are normal and recurring) considered necessary for a fair presentation of the interim financial information have been included. When preparing financial statements in conformity with GAAP, the Company must make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, expenses and related disclosures at the date of the financial statements. Actual results could differ from those estimates. Additionally, operating results for the three and six months ended June 30, 2016 are not necessarily indicative of the results that may be expected for any other interim period or for the fiscal year ending December 31, 2016. For further information, refer to the financial statements and footnotes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2015 as filed with the Securities and Exchange Commission (“SEC”) on March 15, 2016.

Basis of Consolidation

The condensed consolidated financial statements at June 30, 2016 include the accounts of Karyopharm Therapeutics Inc. (a Delaware corporation), the accounts of Karyopharm Securities Corp. (a wholly-owned Massachusetts corporation of the Company incorporated in December 2013), the accounts of Karyopharm Europe GmbH (a wholly-owned German Limited Liability Company formed in August 2014), and the accounts of Karyopharm Therapeutics (Bermuda) Ltd. (a wholly-owned Bermuda subsidiary of the Company formed in March 2015). All intercompany balances and transactions have been eliminated in consolidation.

2. Recently Issued Accounting Pronouncements

In August 2014, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) No. 2014-15, Presentation of Financial Statements—Going Concern (Subtopic 205-40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern. ASU No. 2014-15 is intended to define management’s responsibility to evaluate whether there is substantial doubt about an organization’s ability to continue as a going concern and to provide related footnote disclosures. Substantial doubt about an entity’s ability to continue as a going concern exists when relevant conditions and events, considered in the aggregate, indicate that it is probable that the entity will be unable to meet its obligations as they become due within one year after the date that the financial statements are issued (or available to be issued). ASU No. 2014-15 provides guidance to an organization’s management, with principles and definitions that are intended to reduce diversity in the timing and content of disclosures that are commonly provided by organizations in the financial statement footnotes. ASU No. 2014-15 is effective for annual reporting periods ending after December 15, 2016, and for annual and interim periods thereafter. Early adoption is permitted. The Company does not expect the adoption of ASU No. 2014-15 to have a material impact on its consolidated financial statements, but it may impact the Company’s disclosures.

In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers, which defers the effective date of ASU 2014-09 for all entities by one year. ASU 2014-09 is now effective for public companies for annual reporting periods beginning after December 15, 2017, including interim periods within those reporting periods. Early adoption is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. ASU 2014-09 outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most of the current revenue recognition guidance, including industry-specific guidance. In addition, ASU 2014-09 provides guidance on accounting for certain revenue-related costs including, but not limited to, when to capitalize costs associated with obtaining and fulfilling a contract. ASU 2014-09 provides companies with two implementation methods. Companies can choose to apply the standard retrospectively to each prior reporting period presented (full retrospective application) or retrospectively with the cumulative effect of initially applying the standard as an adjustment to the opening balance of retained earnings of the annual reporting period that includes the date of initial application (modified retrospective application). The Company continues to evaluate the expected impact of this new guidance and available adoption methods.

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). The new standard requires that all lessees recognize the assets and liabilities that arise from leases on the balance sheet and disclose qualitative and quantitative information about its leasing arrangements. The new standard will be effective for the Company on January 1, 2019. The Company is currently evaluating the potential impact that this standard may have on its consolidated financial statements.

7

In March 2016, the FASB issued ASU No. 2016-09, Compensation – Stock Compensation (Topic 718). The new standard identifies areas for simplification involving several aspects of accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, an option to recognize gross stock compensation expense with actual forfeitures recognized as they occur, as well as certain classifications on the statement of cash flows. The standard is effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods. Early adoption is permitted. An entity that elects early adoption must adopt all of the provisions of the standard in the same period. The Company is currently evaluating the potential impact that ASU 2016-09 may have on the Company’s financial position or results of operations.

The Company did not adopt any new accounting pronouncements during the three and six months ended June 30, 2016 that had an effect on the Company’s condensed consolidated financial statements.

3. Fair Value of Financial Instruments

Financial instruments, including cash, restricted cash, prepaid expenses and other current assets, accounts payable and accrued expenses are presented in the condensed consolidated financial statements at amounts that approximate fair value at June 30, 2016 and December 31, 2015.

The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. The fair value hierarchy prioritizes valuation inputs based on the observable nature of those inputs. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments and is not a measure of the investment credit quality. The hierarchy defines three levels of valuation inputs:

Level 1 inputs	Quoted prices in active markets for identical assets or liabilities
Level 2 inputs	Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly
Level 3 inputs	Unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability

Items classified as Level 2 within the valuation hierarchy consist of commercial paper, corporate debt securities and U.S. government agency securities. The Company estimates the fair values of these marketable securities by taking into consideration valuations obtained from third-party pricing sources. These pricing sources utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include market pricing based on real-time trade data for the same or similar securities, issuer credit spreads, benchmark yields, and other observable inputs. The Company validates the prices provided by its third-party pricing sources by understanding the models used, obtaining market values from other pricing sources and analyzing pricing data in certain instances.

The following table presents information about the Company’s financial assets that have been measured at fair value at June 30, 2016 and indicates the fair value hierarchy of the valuation inputs utilized to determine such fair value (in thousands):

Description	Total		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Financial assets
Cash equivalents:
Money market funds	$	27,213	$	27,213	$	—	$	—
Investments:
Current:
Corporate debt securities		63,284		—		63,284		—
Commercial paper		20,733		—		20,733		—
U.S. government and agency securities		1,001		—		1,001		—
Non-current:
Corporate debt securities (one to two year maturity)		38,433		—		38,433		—
U.S. government and agency securities (one to two year maturity)		4,501		—		4,501		—
	$	155,165	$	27,213	$	127,952	$	—

8

The following table presents information about the Company’s financial assets that have been measured at fair value at December 31, 2015 and indicates the fair value hierarchy of the valuation inputs utilized to determine such fair value (in thousands):

Description	Total		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Financial assets
Cash equivalents:
Money market funds	$	49,172	$	49,172	$	—	$	—
Investments:
Current:
Corporate debt securities		86,447		—		86,447		—
Commercial paper		29,828		—		29,828		—
U.S. government and agency securities		1,000		—		1,000		—
Non-current:
Corporate debt securities (one to two year maturity)		33,878		—		33,878		—
	$	200,325	$	49,172	$	151,153	$	—

4. Investments

The following table summarizes the Company’s investments as of June 30, 2016 (in thousands):

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Loss			Fair Value
Current:
Corporate debt securities	$	63,265	$	31	$	(12	)	$	63,284
Commercial paper		20,697		36		—			20,733
U.S. government and agency securities		1,000		1		—			1,001
Non-current:
Corporate debt securities (one to two year maturity)		38,273		160		—			38,433
U.S. government and agency securities (one to two year maturity)		4,500		1		—			4,501
	$	127,735	$	229	$	(12	)	$	127,952

The following table summarizes the Company’s investments as of December 31, 2015 (in thousands):

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Loss			Fair Value
Current:
Corporate debt securities	$	86,515	$	4	$	(72	)	$	86,447
Commercial paper		29,808		20		—			29,828
U.S. government and agency securities		1,000		—		—			1,000
Non-current:
Corporate debt securities (one to two year maturity)		34,019		2		(143	)		33,878
	$	151,342	$	26	$	(215	)	$	151,153

At June 30, 2016 and December 31, 2015, the Company held 19 and 69 debt securities that were in an unrealized loss position for less than one year, respectively. The aggregate fair value of debt securities in an unrealized loss position at June 30, 2016 and December 31, 2015 was $25,406 and $117,851, respectively. There were no individual securities that were in a significant unrealized loss position or that had been in an unrealized loss position for greater than one year as of June 30, 2016 or December 31, 2015.

9

The Company reviews investments for other-than-temporary impairment whenever the fair value of an investment is less than the amortized cost and evidence indicates that an investment’s carrying amount is not recoverable within a reasonable period of time.

Other-than-temporary impairments of investments are recognized in the condensed consolidated statements of operations if the Company has experienced a credit loss and has the intent to sell the investment or if it is more likely than not that the Company will be required to sell the investment before recovery of the amortized cost basis. Evidence considered in this assessment includes reasons for the impairment, compliance with the Company’s investment policy, the severity and the duration of the impairment and changes in value subsequent to the end of the period.

5. Property and Equipment, net

Property and equipment, net consists of the following (in thousands):

	Estimated Useful Life Years		June 30, 2016			December 31, 2015
Laboratory equipment		4	$	538		$	538
Furniture and fixtures		5		361			322
Office and computer equipment		3		360			360
Leasehold improvements		Lesser of useful life or lease term		3,397			3,391
				4,656			4,611
Less accumulated depreciation and amortization				(1,486	)		(1,128	)
			$	3,170		$	3,483

6. Accrued Expenses

Accrued expenses consists of the following (in thousands):

	June 30, 2016		December 31, 2015
Research and development costs	$	8,193	$	8,007
Payroll and employee-related costs		2,099		2,445
Professional fees		462		270
Other		358		301
	$	11,112	$	11,023

7. Net Loss Per Share

Basic and diluted net loss per common share is calculated by dividing net loss by the weighted-average number of common shares outstanding during the period, without consideration for common stock equivalents. The Company’s potentially dilutive shares, which include outstanding stock options and unvested restricted stock and restricted stock units, are considered to be common stock equivalents and are only included in the calculation of diluted net loss per share when their effect is dilutive.

The following potentially dilutive securities were excluded from the calculation of diluted net loss per share due to their anti-dilutive effect:

	Three and Six Months Ended June 30,
	2016		2015
Outstanding stock options		5,421,363		4,326,014
Unvested restricted stock		—		1,421
Unvested restricted stock units		479,000		—

10

8. Stock-based Compensation

Stock options

A summary of the Company’s stock option activity and related information follows:

	Shares			Weighted- Average Exercise Price Per Share		Weighted- Average Remaining Contractual Term (years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2015		4,443,317		$	19.91		8.2	$	15,598
Granted		1,268,400			7.00
Exercised		(62,001	)		3.80
Canceled		(228,353	)		16.88
Outstanding at June 30, 2016		5,421,363		$	17.20		8.1	$	4,986
Exercisable at June 30, 2016		2,324,861		$	16.71		7.3	$	4,104
Vested and expected to vest at June 30, 2016		5,080,019		$	17.37		8.0	$	4,943

As of June 30, 2016, there was $33,944 of total unrecognized stock-based compensation expense related to stock options. The expense is expected to be recognized over a weighted-average period of 2.6 years.

Restricted stock units

A restricted stock unit (“RSU”) represents the right to receive one share of the Company’s common stock upon vesting of the RSU. The fair value of each RSU is based on the closing price of the Company’s common stock on the date of grant. In November 2015, the Company granted RSUs with service conditions that vest in two equal annual installments provided that the employee remains employed with the Company. The following is a summary of RSU activity under the 2013 Plan for the six months ended June 30, 2016:

	Number of Shares Underlying RSUs			Weighted-Average Grant Date Fair Value
Unvested at December 31, 2015		508,800		$	17.39
Granted		25,000			8.06
Forfeited		(17,800	)		17.91
Vested		(37,000	)		11.25
Unvested at June 30, 2016		479,000		$	17.36

The total expense related to RSUs for the six months ended June 30, 2016 and 2015 was $2,367 and $0, respectively. As of June 30, 2016, $5,421 of unrecognized compensation costs related to unvested RSUs are expected to be recognized over a weighted-average period of 1.35 years.

11

Employee Stock Purchase Plan

The Company has an Employee Stock Purchase Plan (“ESPP”) that permits eligible employees to enroll in a twelve-month offering period comprising two six-month purchase periods. Participants may purchase shares of the Company’s common stock, through payroll deductions, at a price equal to 85% of the fair market value of the common stock on the first day of the applicable six-month offering period or the last day of the applicable six-month purchase period, whichever is lower. Purchase dates under the ESPP occur on or about May 1 and November 1 of each year. In 2013, the Company’s stockholders approved the reservation of 242,424 shares of the Company’s common stock for issuance under the ESPP, plus an annual increase to be added on the first day of each fiscal year, commencing on January 1, 2015 and ending on December 31, 2023, equal to the lesser of 484,848 shares of the Company’s common stock, 1% of the number of outstanding shares on such date, or an amount determined by the board of directors.

For the six months ended June 30, 2016 and 2015, the Company withheld $235 and $125, respectively, from employees on an after tax basis related to the purchase of 29,724 and 5,403 shares, respectively, of the Company’s stock under the ESPP.

For the six months ended June 30, 2016 and 2015, the Company recorded stock-based compensation expense related to the ESPP of $116 and $78, respectively. As of June 30, 2016, 508,184 shares of the Company’s common stock remain available for issuance under the ESPP. As of June 30, 2016, there was $73 of total unrecognized stock-based compensation expense related to the ESPP. The expense is expected to be recognized over a period of four months.

9. Commitments and Contingencies

In March 2014, the Company entered into an operating lease for approximately 29,933 square feet of office and research space in Newton, Massachusetts. The Company uses the leased premises as its corporate headquarters and for research and development purposes. The lease was amended on December 31, 2014 by extending the lease term of the lease from November 30, 2021 to September 30, 2022. The amendment provides for the expansion of the premises leased by the Company by approximately 16,234 square feet, and provides the Company with the rights of first offer to lease approximately 27,701 square feet of additional space. The Company may extend the lease term for one additional five year period. The Company is recording rent expense on a straight-line basis through the end of the lease term, inclusive of the period in which there are no scheduled rent payments. The Company has recorded deferred rent on the condensed consolidated balance sheets at June 30, 2016 and December 31, 2015, accordingly. The lease provides the Company with an allowance for improvements of $1,616, all of which was incurred through June 30, 2016. All improvements were deemed normal tenant improvements, were recorded as leasehold improvements and deferred rent and will be recorded as a reduction to rent expense ratably over the lease term. The Company has provided a security deposit in the form of a cash-collateralized letter of credit in the amount of $400, which amount may be reduced to $200 in January 2018. The amount is classified as restricted cash on the condensed consolidated balance sheet.

In November 2014, the Company signed a five-year operating lease agreement in Munich, Germany for approximately 3,681 square feet of office space. The lease is for the period February 2015 through January 2020. Pursuant to the lease agreement, the Company is obligated to make aggregate rent payments of €374 (approximately $414), through January 31, 2020. The Company is recording rent expense on a straight-line basis through the end of the lease term, inclusive of the period in which there are no scheduled rent payments.

The Company recorded rent expense totaling $290 and $240 for the three months ended June 30, 2016 and 2015, respectively, and $579 and $464 for the six months ended June 30, 2016 and 2015, respectively.

10. Equity

Controlled Equity Offering Sales Agreement

On December 7, 2015, the Company entered into a Controlled Equity Offering Sales Agreement (the “Agreement”), with Cantor Fitzgerald & Co., as sales agent (“Cantor”), pursuant to which the Company may issue and sell, from time to time, through Cantor, shares of the Company’s common stock, up to an aggregate offering price of $50.0 million (the “Shares”).

Under the Agreement, Cantor may sell the Shares by methods deemed to be an “at-the-market” offering as defined in Rule 415 promulgated under the Securities Act of 1933, as amended (the “Securities Act”), including sales made directly on The NASDAQ Global Select Market, on any other existing trading market for the Shares or to or through a market maker. In addition, under the Agreement, Cantor may sell the Shares by any other method permitted by law, including in privately negotiated transactions.

The Company is not obligated to make any sales of the Shares under the Agreement. The Company or Cantor may suspend or terminate the offering of Shares upon notice to the other party and subject to other conditions. The Company will pay Cantor a commission of up to 3.0% of the gross proceeds from the sale of the Shares pursuant to the Agreement and has agreed to provide Cantor with customary indemnification and contribution rights.

12

In December 2015, the Company sold an aggregate of 121,314 shares under the Agreement, for net proceeds of approximately $1.5 million. As of July 31, 2016, the Company has not sold any additional shares under the Agreement.

Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations.

You should read the following discussion and analysis of our financial condition and results of operations together with our financial statements and related notes appearing elsewhere in this quarterly report.

FORWARD-LOOKING STATEMENTS

This Quarterly Report on Form 10-Q, including the following discussion, contains forward-looking statements that involve substantial risks and uncertainties. All statements, other than statements of historical facts, contained in this Quarterly Report on Form 10-Q, including statements regarding our strategy, future operations, future financial position, future revenues, projected costs, prospects, plans and objectives of management, are forward looking statements. The words “anticipate,” “believe,” “estimate,” “expect,” “intend,” “may,” “plan,” “predict,” “project,” “target,” “potential,” “will,” “would,” “could,” “should,” “continue” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words.

Forward-looking statements are not guarantees of future performance and our actual results could differ materially from the plans, intentions, expectations or results discussed in the forward-looking statements. Factors that could cause actual results to differ materially from those in the forward-looking statements include, but are not limited to, our ability to raise additional capital to support our clinical development program and other operations, our ability to develop products of commercial value and to identify, discover and obtain rights to additional potential product candidates, our ability to protect and maintain our intellectual property, the outcome of research and development activities and the fact that the preclinical and clinical testing of our compounds may not be predictive of the success of later clinical trials, our reliance on third-parties, competitive developments, the effect of current and future legislation and regulation and regulatory actions, as well as other risks described in our Annual Report on Form 10-K for the year ended December 31, 2015, or 2015 Form 10-K, as filed with the Securities and Exchange Commission, or SEC, on March 15, 2016, and other filings with the SEC.

As a result of these and other factors, we may not actually achieve the plans, intentions, expectations or results disclosed in our forward-looking statements, and you should not place undue reliance on our forward-looking statements. Our forward-looking statements do not reflect the potential impact of any future acquisitions, mergers, dispositions, joint ventures or investments we may make. We do not assume any obligation to update any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law.

OVERVIEW

We are a clinical-stage pharmaceutical company focused on the discovery, development and subsequent commercialization of novel, first-in-class drugs directed against nuclear transport and related targets for the treatment of cancer and other major diseases. Our scientific expertise is focused on understanding the regulation of intracellular communication between the nucleus and the cytoplasm. We have discovered and are developing wholly-owned, novel, small molecule Selective Inhibitor of Nuclear Export, or SINE™, compounds that inhibit the nuclear export protein XPO1. These SINE compounds represent a new class of drug candidates with a novel mechanism of action that have the potential to treat a variety of diseases in areas of unmet medical need. Our SINE compounds were the first oral XPO1 inhibitors in clinical development.

Our initial focus is on seeking the regulatory approval and commercialization of our lead drug candidate, selinexor (KPT-330), as an orally administered agent in cancer indications with significant unmet clinical need, initially for hematologic malignancies. We then plan to seek additional approvals for the use of selinexor in combination therapies to expand the patient populations that are eligible for selinexor, as well as to move selinexor towards front-line cancer therapy. We are also advancing the clinical development of selinexor in multiple solid tumor indications. To date, we have initiated multiple later-phase clinical trials to evaluate selinexor in hematological cancers and solid tumors including the Phase 2b STORM study in multiple myeloma, the Phase 2 SOPRA study in acute myeloid leukemia (AML), the Phase 2b SADAL study in diffuse large B-cell lymphoma (DLBCL) and the Phase 2/3 SEAL study in liposarcoma. We expect to provide topline data for STORM in September 2016, interim analysis and topline data for SOPRA in late 2016 and mid-2017, respectively, topline data for SADAL in early 2017 and topline data for the Phase 2 portion of SEAL in mid-2017.. We are preparing to establish the commercial infrastructure to support a potential launch of selinexor for hematologic indications in North America and Western Europe.

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We have devoted substantially all of our efforts to research and development. We expect that it will be several years, if ever, before we have a drug candidate ready for commercialization for the treatment of human disease. To date, we have financed our operations primarily with the net proceeds from the private placements of our preferred stock and the net proceeds from our public offerings of our common stock.

As of June 30, 2016, we had an accumulated deficit of $313.7 million. We had net losses of $30.2 million and $32.7 million for the three months ended June 30, 2016 and 2015, respectively, and net losses of $57.2 million and $58.8 million for the six months ended June 30, 2016 and 2015, respectively. We have not generated any revenue to date from the sales of any drugs.

We expect to continue to incur significant expenses and increasing operating losses for the foreseeable future. The net losses we incur may fluctuate significantly from quarter to quarter. We anticipate that our expenses will increase substantially if and as we:

• continue our research and preclinical and clinical development of our drug candidates;

• initiate additional clinical trials for our drug candidates;

• seek marketing approvals for any of our drug candidates that successfully complete clinical trials;

• establish a sales, marketing and distribution infrastructure to commercialize any drugs for which we may obtain marketing approval;

• maintain, expand and protect our intellectual property portfolio;

• manufacture our drug candidates;

• hire additional clinical, quality control and scientific personnel;

• identify additional drug candidates;

• acquire or in-license other drugs and technologies; and

• add operational, financial and management information systems and personnel, including personnel to support our drug development, any future commercialization efforts and our other operations as a public company.

CRITICAL ACCOUNTING POLICIES AND SIGNIFICANT JUDGMENTS AND ESTIMATES

We believe that several accounting policies are important to understanding our historical and future performance. We refer to these policies as “critical” because these specific areas generally require us to make judgments and estimates about matters that are uncertain at the time we make the estimate, and different estimates—which also would have been reasonable—could have been used, which would have resulted in different financial results.

There were no changes to the critical accounting policies we identified in the 2015 Form 10-K. It is important that the discussion of our operating results that follows be read in conjunction with the critical accounting policies disclosed in the 2015 Form 10-K.

RESULTS OF OPERATIONS

Comparison of the Three Months Ended June 30, 2016 and June 30, 2015

	Three Months Ended June 30,
	2016			2015			$ Change			% Change
	(in thousands)
Contract and grant revenue	$	59		$	150		$	(91	)		(61	)%
Operating expenses:
Research and development		24,579			27,006			(2,427	)		(9	)%
General and administrative		5,956			6,157			(201	)		(3	)%
Loss from operations		(30,476	)		(33,013	)		2,537			8	%
Other income, net		318			318			—			—	%
Net loss	$	(30,158	)	$	(32,695	)	$	2,537			8	%

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Contract and Grant Revenue. We recognized revenue in 2016 pursuant to a government grant agreement and in 2015 pursuant to a sponsored research agreement. Contract and grant revenue for the three months ended June 30, 2016 and June 30, 2015 was not material to the financial statements.

Research and Development Expense. Research and development expense decreased approximately $2.4 million to $24.6 million for the three months ended June 30, 2016 from approximately $27.0 million for the three months ended June 30, 2015. We expect research and development expense to remain consistent for the rest of the year. The decrease is primarily related to:

• an increase of $2.1 million in personnel costs, primarily due to increased headcount and an increase of $1.3 million in stock-based compensation expense related to equity awards granted to personnel;

• a decrease of approximately $1.4 million in selinexor clinical trial costs;

• a decrease of $1.5 million in preclinical efficacy and toxicology study costs; and

• a decrease of $1.6 million in consulting expense.

General and Administrative Expense. General and administrative expense decreased approximately $0.2 million to $6.0 million for the three months ended June 30, 2016 from approximately $6.2 million for the three months ended June 30, 2015. We expect general and administrative expense to remain consistent for the rest of the year. The decrease is primarily related to:

• an increase of approximately $0.9 million in personnel costs, primarily due to increased headcount and an increase of approximately $0.6 million in stock-based compensation expense related to equity awards granted to personnel;

• a decrease of approximately $0.9 million in consulting and professional expense; and

• a decrease of $0.2 million in occupancy, travel and other expense.

Other Income, net. Other income, net, remained unchanged for the three months ended June 30, 2016 compared to the three months ended June 30, 2015.

Comparison of the Six Months Ended June 30, 2016 and June 30, 2015

	Six Months Ended June 30,
	2016			2015			$ Change			% Change
	(in thousands)
Contract and grant revenue	$	59		$	150		$	(91	)		(61	)%
Operating expenses:
Research and development		46,374			47,757			(1,383	)		(3	)%
General and administrative		11,510			11,556			(46	)		—	%
Loss from operations		(57,825	)		(59,163	)		1,338			2	%
Other income, net		608			401			207			52	%
Net loss	$	(57,217	)	$	(58,762	)	$	1,545			3	%

Contract and Grant Revenue. We recognized revenue in 2016 pursuant to a government grant agreement and in 2015 pursuant to a sponsored research agreement. Contract and grant revenue for the six months ended June 30, 2016 and June 30, 2015 was not material to the financial statements.

Research and Development Expense. Research and development expense decreased approximately $1.4 million to $46.4 million for the six months ended June 30, 2016 from approximately $47.8 million for the six months ended June 30, 2015. We expect research and development expense to remain consistent for the rest of the year. The decrease is primarily related to:

• an increase of $4.4 million in personnel costs, primarily due to increased headcount and an increase of $2.5 million in stock-based compensation expense related to equity awards granted to personnel;

• a decrease of approximately $1.9 million in selinexor clinical trial costs;

• a decrease of $3.1 million in preclinical efficacy and toxicology study costs; and

• a decrease of $0.8 million in consulting and professional expense.

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General and Administrative Expense. General and administrative decreased approximately $0.1 million to $11.5 million for the six months ended June 30, 2016 from approximately $11.6 million for the six months ended June 30, 2015. We expect general and administrative expense to remain consistent for the rest of the year. The decrease is primarily related to:

• an increase of approximately $1.8 million in personnel costs, primarily due to increased headcount and an increase of approximately $1.1 million in stock-based compensation expense related to equity awards granted to personnel;

• a decrease of approximately $1.5 million in consulting and professional expense; and

• a decrease of $0.4 million in occupancy, travel and other expense.

Other Income, net. Other income, net, increased by approximately $0.2 million to approximately $0.6 million for the six months ended June 30, 2016, from $0.4 million for the six months ended June 30, 2015, due to increased interest income earned on investment account balances.

LIQUIDITY AND CAPITAL RESOURCES

Sources of Liquidity

To date, we have not generated any material revenues. We have financed our operations to date principally through private placements of our preferred stock and proceeds from our public offerings of our common stock.

As of June 30, 2016, we had $166.2 million in cash, cash equivalents, restricted cash and short- and long-term investments. In January 2015, we completed an underwritten offering of 2,950,000 shares of our common stock at public offering price of $33.00 per share. We received net proceeds of approximately $90.8 million, after deducting the underwriting discount and offering expenses payable by us.

As of December 31, 2015, we commenced an “at-the-market” offering of our common stock, pursuant to which we may sell shares of our common stock with an aggregate offering price of up to $50.0 million. In December 2015, the Company sold an aggregate of 121,314 shares of common stock in this offering for net proceeds of approximately $1.5 million. As of July 31, 2016, we have not sold any additional shares under this “at-the-market” offering.

Cash Flows

The following table provides information regarding our cash flows:

	Six Months Ended June 30,
	2016			2015
	(in thousands)
Net cash used in operating activities	$	(44,059	)	$	(48,324	)
Net cash provided by (used in) investing activities		22,968			(169,222	)
Net cash provided by financing activities		436			91,177
Effect of exchange rate changes		14			(9	)
Net decrease in cash and cash equivalents	$	(20,641	)	$	(126,378	)

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Operating activities. The cash used in operating activities in all periods resulted primarily from our net losses adjusted for non-cash charges and changes in the components of working capital. The decrease in cash used in operating activities during the six months ended June 30, 2016 compared to the six months ended June 30, 2015 was driven primarily by a decrease in our net loss adjusted for non-cash charges and changes in the components of working capital due to a decrease in research and development expenses as we decreased costs related to preclinical toxicology and drug supply.

Investing activities. The cash provided by investing activities during the six months ended June 30, 2016 reflects an increase of $192.2 million compared to the six months ended June 30, 2015. The increase was primarily related to an increase of $69.0 million in maturities of investments, combined with a decrease of $122.5 million in the purchase of investments.

Financing activities. The cash provided by financing activities for the six months ended June 30, 2016 reflects a decrease of $90.7 million compared to the six months ended June 30, 2015. We had net proceeds of approximately $90.8 million from the sale of common stock as part of a public offering of our common stock in January 2015.

Funding Requirements

We expect our expenses to increase in connection with our ongoing activities, particularly as we continue the clinical trials of, and assuming positive results of our clinical trials and based on regulatory feedback, if and when we seek marketing approval for, selinexor and our other drug candidates. In addition, if we obtain marketing approval for any of our drug candidates, we expect to incur significant commercialization expenses related to drug sales, marketing, manufacturing and distribution to the extent that such sales, marketing, manufacturing and distribution are not the responsibility of any collaborator that we may have at such time for any such drug. Furthermore, we expect to continue to incur additional costs associated with operating as a public company. Accordingly, we will need to obtain substantial additional funding in connection with our continuing operations. If we are unable to raise capital when needed or on attractive terms, we would be forced to delay, reduce or eliminate our research and development programs or future commercialization efforts.

We expect that our existing cash, cash equivalents and short- and long-term investments will enable us to fund our current operating plan and capital expenditure requirements into the middle of 2018. We expect to finish 2016 with greater than $120 million in cash, cash equivalents, restricted cash and investments. Our future capital requirements will depend on many factors, including:

• the progress and results of our current and planned clinical trials of selinexor;

• the scope, progress, results and costs of drug discovery, preclinical development, laboratory testing and clinical trials for our other drug candidates;

• the costs, timing and outcome of regulatory review of our drug candidates;

• our ability to establish and maintain collaborations on favorable terms, if at all;

• the success of any collaborations that we may enter into with third parties;

• the extent to which we acquire or in-license other drugs and technologies;

• the costs of future commercialization activities, including drug sales, marketing, manufacturing and distribution, for any of our drug candidates for which we receive marketing approval, to the extent that such sales, marketing, manufacturing and distribution are not the responsibility of any collaborator that we may have at such time;

• the amount of revenue, if any, received from commercial sales of our drug candidates, should any of our drug candidates receive marketing approval; and

• the costs of preparing, filing and prosecuting patent applications, maintaining and enforcing our intellectual property rights and defending intellectual property-related claims.

Identifying potential drug candidates and conducting preclinical studies and clinical trials is a time-consuming, expensive and uncertain process that takes years to complete, and we may never generate the necessary data or results required to obtain marketing approval and achieve drug sales. In addition, our drug candidates, if approved, may not achieve commercial success. Our commercial revenues, if any, will be derived from sales of drugs that we do not expect to be commercially available for many years, if at all. Accordingly, we will need to continue to rely on additional financing to achieve our business objectives. Adequate additional financing may not be available to us on acceptable terms, or at all. In addition, we may seek additional capital due to favorable market conditions or strategic considerations, even if we believe we have sufficient funds for our current or future operating plans.

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Contractual Obligations

There have been no material changes to our contractual obligations described under Management’s Discussion and Analysis of Financial Condition and Results of Operations in the 2015 Form 10-K.

OFF-BALANCE SHEET ARRANGEMENTS

We did not have during the periods presented, and we do not currently have, any off-balance sheet arrangements, as defined under SEC rules.

Item 3. Quantitative and Qualitative Disclosures About Market Risk.

We are exposed to market risk related to changes in interest rates. We had cash, cash equivalents, restricted cash and investments of $166.2 million as of June 30, 2016. Our primary exposure to market risk is interest rate sensitivity, which is affected by changes in the general level of U.S. interest rates, particularly because all of our investments are in short-term securities. Due to the short-term duration of our investment portfolio and the low risk profile of our investments, an immediate 10% change in interest rates would not have a material effect on the fair market value of our investment portfolio.

We do not believe our cash, cash equivalents, restricted cash and investments have significant risk of default or illiquidity. While we believe our cash, cash equivalents and investments do not contain excessive risk, we cannot provide absolute assurance that in the future our investments will not be subject to adverse changes in securities at one or more financial institutions that are in excess of federally insured limits. Give the potential instability of financial institutions, we cannot provide assurance that we will not experience losses on these deposits.

We are also exposed to market risk related to change in foreign currency exchange rates. We contract with contract research organizations and contract manufacturing organizations that are located in Canada and Europe, which are denominated in foreign currencies. We also contract with a number of clinical trial sites outside the United States, and our budgets for those studies are frequently denominated in foreign currencies. We are subject to fluctuations in foreign currency rates in connection with these agreements. We do not currently hedge our foreign currency exchange rate risk.

Item 4. Controls and Procedures.

Evaluation of Disclosure Controls and Procedures

Our management, with the participation of our Chief Executive Officer and Executive Vice President and Chief Financial Officer, evaluated the effectiveness of our disclosure controls and procedures as of June 30, 2016. The term “disclosure controls and procedures,” as defined in Rules 13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), means controls and other procedures of a company that are designed to ensure that information required to be disclosed by a company in the reports that it files or submits under the Exchange Act is recorded, processed, summarized and reported, within the time periods specified in the SEC’s rules and forms. Disclosure controls and procedures include, without limitation, controls and procedures designed to ensure that information required to be disclosed by a company in the reports that it files or submits under the Exchange Act is accumulated and communicated to the Company’s management, including its principal executive and principal financial officers, as appropriate to allow timely decisions regarding required disclosure. Management recognizes that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving their objectives and management necessarily applies its judgment in evaluating the cost-benefit relationship of possible controls and procedures. Based on the evaluation of our disclosure controls and procedures as of June 30, 2016, our Chief Executive Officer and Executive Vice President and Chief Financial Officer concluded that, as of such date, our disclosure controls and procedures were effective at the reasonable assurance level.

Changes in Internal Control Over Financial Reporting

No change in our internal control over financial reporting occurred during the fiscal quarter ended June 30, 2016 that has materially affected, or is reasonably likely to materially affect, the Company’s internal control over financial reporting.

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PART II—OTHER INFORMATION

Item 1A. Risk Factors.

Careful consideration should be given to the following risk factors, in addition to the other information set forth in this Quarterly Report on Form 10-Q and in other documents that we file with the SEC, in evaluating the Company and our business. Investing in our common stock involves a high degree of risk. If any of the following risks and uncertainties actually occurs, our business, prospects, financial condition and results of operations could be materially and adversely affected. The risks described below are not intended to be exhaustive and are not the only risks facing the Company. New risk factors can emerge from time to time, and it is not possible to predict the impact that any factor or combination of factors may have on our business, prospects, financial condition and results of operations.

Risks Related to the Discovery, Development and Commercialization of Our Drug Candidates

We depend heavily on the success of our lead drug candidate selinexor (KPT-330), which is currently in clinical trials. Our clinical trials of selinexor may not be successful. If we are unable to commercialize selinexor or experience significant delays in doing so, our business will be materially harmed.

We have invested a significant portion of our efforts and financial resources in the research and development of our lead drug candidate, selinexor. Our ability to generate revenues from the sale of drugs that treat cancer and other diseases in humans, which we do not expect to occur for several years, if ever, will depend heavily on the successful development, regulatory approval and eventual commercialization of selinexor.

We cannot commercialize drug candidates in the United States without first obtaining regulatory approval for the drug from the U.S. Food and Drug Administration, or FDA; similarly, we cannot commercialize drug candidates outside of the United States without obtaining regulatory approval from similar regulatory authorities outside of the United States. Even if selinexor or another drug candidate were to successfully obtain approval from the FDA and non-U.S. regulatory authorities, any approval might contain significant limitations related to use restrictions for specified age groups, warnings, precautions or contraindications, or may be subject to burdensome post-approval study or risk management requirements. If we are unable to obtain regulatory approval for selinexor in one or more jurisdictions, or any approval contains significant limitations, we may not be able to obtain sufficient funding or generate sufficient revenue to continue the development, marketing and/or commercialization of selinexor or any other drug candidate that we may discover, in-license, develop or acquire in the future. Furthermore, even if we obtain regulatory approval for selinexor, we will still need to develop a commercial organization, or collaborate with a third party for the commercialization of selinexor, establish commercially viable pricing and obtain approval for adequate reimbursement from third-party and government payors. If we or our commercialization collaborators are unable to successfully commercialize selinexor, we may not be able to generate sufficient revenues to continue our business.

The results of previous clinical trials may not be predictive of future results, and the results of our current and planned clinical trials may not satisfy the requirements of the FDA or non-U.S. regulatory authorities.

We currently have no drugs approved for sale and we cannot guarantee that we will ever have marketable drugs. Clinical failure can occur at any stage of clinical development. Clinical trials may produce negative or inconclusive results, and we or any future collaborators may decide, or regulators may require us, to conduct additional clinical trials or preclinical studies. We will be required to demonstrate with substantial evidence through well-controlled clinical trials that our drug candidates are safe and effective for use in a diverse population before we can seek regulatory approvals for their commercial sale. Success in early-stage clinical trials does not mean that future larger registration clinical trials will be successful because drug candidates in later-stage clinical trials may fail to demonstrate sufficient safety and efficacy to the satisfaction of the FDA and non-U.S. regulatory authorities despite having progressed through early-stage clinical trials. Drug candidates that have shown promising results in early-stage clinical trials may still suffer significant setbacks in subsequent registration clinical trials. Additionally, the outcome of preclinical studies and early-stage clinical trials may not be predictive of the success of later-stage clinical trials and interim results of a clinical trial are not necessarily indicative of final results.

In addition, the design of a clinical trial can determine whether its results will support approval of a drug and flaws in the design of a clinical trial may not become apparent until the clinical trial is well advanced. We have limited experience in designing clinical trials and may be unable to design and conduct a clinical trial to support regulatory approval. Further, if our drug candidates are found to be unsafe or lack efficacy, we will not be able to obtain regulatory approval for them and our business would be harmed. A number of companies in the pharmaceutical industry, including those with greater resources and experience than us, have suffered significant setbacks in advanced clinical trials, even after obtaining promising results in earlier clinical trials.

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In some instances, there can be significant variability in safety and/or efficacy results between different trials of the same drug candidate due to numerous factors, including changes in trial protocols, differences in size and type of the patient populations, adherence to the dosing regimen and other trial protocols and the rate of dropout among clinical trial participants. We do not know whether any Phase 2, Phase 3 or other clinical trials we may conduct will demonstrate consistent or adequate efficacy and safety sufficient to obtain regulatory approval to market our drug candidates.

Further, our drug candidates may not be approved even if they achieve their primary endpoints in Phase 3 clinical trials or other registration trials. The FDA or non-U.S. regulatory authorities may disagree with our trial design and our interpretation of data from preclinical studies and clinical trials. In addition, any of these regulatory authorities may change requirements for the approval of a drug candidate even after reviewing and providing comments or advice on a protocol for a clinical trial that has the potential to result in approval by the FDA or another regulatory authority. In addition, any of these regulatory authorities may also approve a drug candidate for fewer or more limited indications than we request or may grant approval contingent on the performance of costly post-marketing clinical trials. In addition, the FDA or other non-U.S. regulatory authorities may not approve the labeling claims that we believe would be necessary or desirable for the successful commercialization of our drug candidates.

To date, we have had limited discussions with the FDA and non-U.S. regulatory authorities regarding the design of our later phase clinical trials for selinexor, of which we have commenced five such clinical trials. We plan to seek regulatory approvals of selinexor in North America and Europe in each indication with respect to which such later phase clinical trial is being conducted and with respect to which we receive positive results that may support full or accelerated approval, as the case may be. We may also seek such approvals in other geographies. We cannot be certain that we will commence additional later phase trials or complete ongoing later phase trials as anticipated. Before obtaining regulatory approvals for the commercial sale of any drug candidate for a target indication, we must demonstrate with substantial evidence gathered in preclinical studies and well-controlled clinical studies, and, with respect to approval in the United States, to the satisfaction of the FDA, that the drug candidate is safe and effective for use for that target indication. There is no assurance that the FDA or non-U.S. regulatory authorities would consider our current and planned later phase clinical trials to be sufficient to serve as the basis for filing for approval or to gain approval of selinexor for any indication. The FDA and non-U.S. regulatory authorities retain broad discretion in evaluating the results of our clinical trials and in determining whether the results demonstrate that selinexor is safe and effective. If we are required to conduct additional clinical trials of selinexor prior to approval, including additional earlier phase clinical trials that may be required prior to commencing any later phase clinical trials, or additional clinical trials following completion of our current and planned later phase clinical trials, we will need substantial additional funds and there is no assurance that the results of any such additional clinical trials will be sufficient for approval.

The results to date in preclinical and early clinical studies conducted by us or our academic collaborators and in Phase 1 and Phase 2 clinical trials that we are currently conducting include the response of tumors to selinexor. We expect that in any later phase clinical trial where patients are randomized to receive either selinexor on the one hand, or standard of care, supportive care or placebo on the other hand, the primary endpoint will be either progression free survival, meaning the length of time on treatment until objective tumor progression, or overall survival, while the primary endpoint in any later phase clinical trial that is not similarly randomized may be different. For example, the primary endpoint of our SOPRA study, the clinical trial of selinexor in patients over 60 years of age with relapsed and/or refractory acute myeloid leukemia (AML) in first relapse, who are not candidates for intensive chemotherapy or transplantation, is overall survival. Similarly, the primary endpoint of our SEAL study, the clinical trial of selinexor in patients with dedifferentiated liposarcoma, is progression free survival. We are in the early stages of collecting clinical data in humans relating to the impact of selinexor on overall survival and comparative clinical data between selinexor and supportive care. If selinexor does not demonstrate an overall survival benefit, it will likely not be approved. In some instances, the FDA and other regulatory bodies have accepted overall response rate as a surrogate for a clinical benefit, and have granted regulatory approvals based on this or other surrogate endpoints. Overall response rate is defined as the portion of patients with tumor size reduction of a predefined amount for a minimum time period. For some types of cancer, we may use overall response rate as a primary endpoint, as we are doing in our Selinexor Against Diffuse Aggressive Lymphoma (SADAL) study; our Selinexor In Initial or Relapsed/Refractory Richter’s Transformation (SIRRT) study and our Selinexor Treatment Of Refractory Myeloma (STORM) study. These clinical trials will not be randomized against control arms and the primary endpoints of these trials are overall response rate. If selinexor does not demonstrate sufficient overall response rates in these indications, or any other indication for which a clinical trial has overall response rate as a primary endpoint, or if the FDA or non-U.S. regulatory authorities do not deem overall response rate a sufficient endpoint, it will likely not be approved for that indication.

We are early in our development efforts with a limited number of drug candidates in human clinical development. If we are unable to successfully develop and commercialize our drug candidates or experience significant delays in doing so, our business will be materially harmed.

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We are early in our development efforts and have four drug candidates, selinexor, verdinexor, KPT-8602 and KPT-9274, in clinical development for treatment of human diseases. The success of these and any of our other drug candidates will depend on several factors, including the following:

• successful completion of preclinical studies;

• successful enrollment in, and completion of, clinical trials, including demonstration of a favorable risk-benefit ratio;

• receipt of marketing approvals from applicable regulatory authorities;

• establishing commercial manufacturing capabilities or making arrangements with third-party manufacturers;

• obtaining and maintaining patent and trade secret protection and regulatory exclusivity for our drug candidates;

• establishing sales, marketing, manufacturing and distribution capabilities to commercialize any drugs for which we may obtain marketing approval;

• launching commercial sales of the drugs, if and when approved, whether alone or in collaboration with others;

• acceptance of the drugs, if and when approved, by patients, the medical community and third-party payors;

• effectively competing with other therapies;

• obtaining and maintaining coverage and adequate reimbursement by third-party payors, including government payors, for any approved drugs;

• maintaining an acceptable safety profile of the drugs following approval;

• enforcing and defending intellectual property rights and claims; and

• maintaining and growing an organization of scientists and business people, and possibly collaborators, who can develop and commercialize our drug candidates.

If we do not achieve one or more of these factors in a timely manner or at all, we could experience significant delays or an inability to successfully commercialize our drug candidates, which would materially harm our business.

We may seek approval from the FDA or comparable non-U.S. regulatory authorities to use accelerated development pathways for our product candidates. If we are not able to use such pathways, we may be required to conduct additional clinical trials beyond those that we contemplate and that would increase the expense of obtaining, and delay the receipt of, necessary marketing approvals, if we receive them at all. In addition, even if we are able to use an accelerated approval pathway, it may not lead to expedited approval of our product candidates.

Under the Federal Food, Drug and Cosmetic Act, or FDCA, and implementing regulations, the FDA may grant accelerated approval to a product candidate to treat a serious or life-threatening condition that provides meaningful therapeutic benefit over available therapies, upon a determination that the product has an effect on a surrogate endpoint or intermediate clinical endpoint that is reasonably likely to predict clinical benefit. The FDA considers a clinical benefit to be a positive therapeutic effect that is clinically meaningful in the context of a given disease, such as irreversible morbidity or mortality. For the purposes of accelerated approval, a surrogate endpoint is a marker, such as a laboratory measurement, radiographic image, physical sign, or other measure that is thought to predict clinical benefit, but is not itself a measure of clinical benefit. An intermediate clinical endpoint is a clinical endpoint that can be measured earlier than an effect on irreversible morbidity or mortality that is reasonably likely to predict an effect on irreversible morbidity or mortality or other clinical benefit measurement of a therapeutic effect that is considered reasonably likely to predict the clinical benefit of a drug. The accelerated approval pathway may be used in cases in which the advantage of a new drug over available therapy may not be a direct therapeutic advantage, but is a clinically important improvement from a patient and public health perspective.

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Prior to seeking such accelerated approval, we will seek feedback from the FDA and will otherwise evaluate our ability to seek and receive such accelerated approval. There can be no assurance that the FDA will agree with our surrogate endpoints or intermediate clinical endpoints. There can also be no assurance that we will decide to pursue or submit an NDA for accelerated approval or any other form of expedited development, review or approval. Similarly, there can be no assurance that, after feedback from FDA, we will continue to pursue or apply for accelerated approval or any other form of expedited development, review or approval, even if we initially decide to do so. Furthermore, if we decide to submit an application for accelerated approval or under another expedited regulatory designation, there can be no assurance that such submission or application will be accepted or that any expedited development, review or approval will be granted on a timely basis, or at all.

Moreover, for drugs granted accelerated approval, the FDA typically requires post-marketing confirmatory trials to evaluate the anticipated effect on irreversible morbidity or mortality or other clinical benefit. These confirmatory trials must be completed with due diligence. The FDA may withdraw approval of our product candidate approved under the accelerated approval pathway if, for example, the trial required to verify the predicted clinical benefit of our product candidate fails to verify such benefit or does not demonstrate sufficient clinical benefit to justify the risks associated with the drug. The FDA may also withdraw approval if other evidence demonstrates that our product candidate is not shown to be safe or effective under the conditions of use, we fail to conduct any required post approval trial of our product candidate with due diligence, or we disseminate false or misleading promotional materials relating to our product candidate. A failure to obtain accelerated approval or any other form of expedited development, review or approval for our product candidates, or withdrawal of a product candidate, would result in a longer time period for commercialization of such product candidate, could increase the cost of development of such product candidate and could harm our competitive position in the marketplace.

Our approach to the discovery and development of drug candidates that target Exportin 1, or XPO1, is unproven, and we do not know whether we will be able to develop any drugs of commercial value. If selinexor is unsuccessful in proving that drug candidates targeting XPO1 have commercial value or experiences significant delays in doing so, our business may be materially harmed.

Our SINE™ compounds inhibit the nuclear export protein XPO1. We believe that no currently approved cancer treatments are selectively targeting the restoration and increase in the levels of multiple tumor suppressor proteins in the nucleus. Despite promising results to date in preclinical and early clinical studies of selinexor that we have conducted and in Phase 1 and Phase 2 clinical trials of selinexor conducted by us or our academic collaborators, we may not succeed in demonstrating safety and efficacy of SINE™ compounds in our current and future human clinical trials. Any drug candidates that we develop may not effectively prevent the exportation of tumor suppressor and/or growth regulatory proteins from the nucleus in humans with a particular form of cancer. If selinexor is unsuccessful in proving that drug candidates targeting the regulation of intracellular transport of XPO1 have commercial value or experiences significant delays in doing so, our business may be materially harmed and we may not be able to generate sufficient revenues to continue our business.

We may not be successful in our efforts to identify or discover additional potential drug candidates.

Part of our strategy involves identifying and developing drug candidates to build a pipeline of novel drug candidates. Our drug discovery efforts may not be successful in identifying compounds that are useful in treating cancer or other diseases. Our research programs may initially show promise in identifying potential drug candidates, yet fail to yield drug candidates for clinical development for a number of reasons, including:

• the research methodology used may not be successful in identifying potential drug candidates;

• potential drug candidates may, on further study, be shown to have harmful side effects or other characteristics that indicate that they are unlikely to be drugs that will receive marketing approval and/or achieve market acceptance; or

• potential drug candidates may not be effective in treating their targeted diseases.

Research programs to identify new drug candidates require substantial technical, financial and human resources. We may choose to focus our efforts and resources on a potential drug candidate that ultimately proves to be unsuccessful.

If we are unable to identify suitable compounds for preclinical and clinical development, we will not be able to obtain revenues from sale of drugs in future periods, which likely would result in significant harm to our financial position and adversely impact our stock price.

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Clinical drug development is a lengthy and expensive process, with an uncertain outcome. If clinical trials of our drug candidates fail to demonstrate safety and efficacy to the satisfaction of regulatory authorities or do not otherwise produce positive results, we may incur additional costs or experience delays in completing, or ultimately be unable to complete, the development and commercialization of our drug candidates.

Before obtaining marketing approval from regulatory authorities for the sale of our drug candidates, we must complete preclinical development and then conduct extensive clinical trials to demonstrate the safety and efficacy of our drug candidates in humans. Clinical testing is expensive, difficult to design and implement, can take many years to complete and is uncertain as to outcome. A failure of one or more clinical trials can occur at any stage of testing. The outcome of preclinical studies and early-stage clinical trials may not be predictive of the success of later clinical trials, and interim results of a clinical trial do not necessarily predict final results. For example, the results of our Phase 1 and Phase 2 clinical trials of selinexor to date are based on unaudited data provided by our clinical trial investigators. An audit of this data may change the conclusions drawn from this unaudited data provided by our clinical trial investigators indicating less promising results than we currently anticipate. Moreover, preclinical and clinical data are often susceptible to varying interpretations and analyses, and many companies that believed their drug candidates performed satisfactorily in preclinical studies and clinical trials have nonetheless failed to obtain marketing approval of their drugs.

We may experience numerous unforeseen events during, or as a result of, clinical trials that could delay or prevent our ability to receive marketing approval or commercialize our drug candidates, including:

• regulatory authorities or institutional review boards may not authorize us or our investigators to commence a clinical trial or conduct a clinical trial at a prospective trial site;

• feedback from regulatory authorities that requires us to modify the design of our clinical trials;

• we may have delays in reaching or fail to reach agreement on acceptable clinical trial contracts or clinical trial protocols with prospective trial sites or contract research organizations;

• clinical trials of our drug candidates may produce negative or inconclusive results, and we may decide, or regulatory authorities may require us, to conduct additional clinical trials, suspend ongoing clinical trials or abandon drug development programs;

• the number of patients required for clinical trials of our drug candidates may be larger than we anticipate, enrollment in these clinical trials may be slower than we anticipate or participants may drop out of these clinical trials at a higher rate than we anticipate;

• our third-party contractors may fail to comply with regulatory requirements or meet their contractual obligations to us in a timely manner, or at all;

• we or our investigators might have to suspend or terminate clinical trials of our drug candidates for various reasons, including non-compliance with regulatory requirements, a finding that our drug candidates have undesirable side effects or other unexpected characteristics, or a finding that the participants are being exposed to unacceptable health risks;

• the cost of clinical trials of our drug candidates may be greater than we anticipate;

• the supply or quality of our drug candidates or other materials necessary to conduct clinical trials of our drug candidates may be insufficient or inadequate;

• regulators may revise the requirements for approving our drug candidates, or such requirements may not be as we anticipate; and

• any future collaborators that conduct clinical trials may face any of the above issues, and may conduct clinical trials in ways they view as advantageous to them but that are suboptimal for us.

If we are required to conduct additional clinical trials or other testing of our drug candidates beyond those that we currently contemplate, if we are unable to successfully complete clinical trials of our drug candidates or other testing, if the results of these trials or tests are not positive or are only modestly positive or if there are safety concerns, we may:

• be delayed in obtaining marketing approval for our drug candidates;

• not obtain marketing approval at all;

• obtain marketing approval in some countries and not in others;

• obtain approval for indications or patient populations that are not as broad as intended or desired;

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• obtain approval with labeling that includes significant use or distribution restrictions or safety warnings, including boxed warnings;

• be subject to additional post-marketing testing requirements; or

• have the drug removed from the market after obtaining marketing approval.

Our drug development costs will also increase if we experience delays in testing or marketing approvals. We do not know whether clinical trials will begin as planned, will need to be restructured or will be completed on schedule, or at all. Significant clinical trial delays also could shorten any periods during which we may have the exclusive right to commercialize our drug candidates, allow our competitors to bring drugs to market before we do or impair our ability to successfully commercialize our drug candidates, which would harm our business and results of operations.

If we experience delays or difficulties in the enrollment of patients in clinical trials, our receipt of necessary regulatory approvals could be delayed or prevented.

We may not be able to initiate or continue clinical trials for our drug candidates if we are unable to locate and enroll a sufficient number of eligible patients to participate in these trials as required by the FDA or similar regulatory authorities outside of the United States. In addition, some of our competitors may have ongoing clinical trials for drug candidates that treat the same indications as our drug candidates, and patients who would otherwise be eligible for our clinical trials may instead enroll in clinical trials of our competitors’ drug candidates.

Patient enrollment is affected by other factors, including:

• severity of the disease under investigation;

• availability and efficacy of approved drugs for the disease under investigation;

• patient eligibility criteria for the study in question;

• competing drugs in clinical development;

• perceived risks and benefits of the drug candidate under study;

• efforts to facilitate timely enrollment in clinical trials;

• patient referral practices of physicians;

• the ability to monitor patients adequately during and after treatment; and

• proximity and availability of clinical trial sites for prospective patients.

Our inability to enroll a sufficient number of patients for our clinical trials would result in significant delays or may require us to abandon one or more clinical trials altogether. Enrollment delays in our clinical trials may result in increased development costs for our drug candidates, which would cause the value of our company to decline and limit our ability to obtain additional financing.

If serious adverse or unacceptable side effects are identified during the development of our drug candidates or we observe limited efficacy of our drug candidates, we may need to abandon or limit the development of one or more of our drug candidates.

Four of our drug candidates are in clinical development for treatment of human diseases and our other drug candidates for human diseases are in preclinical development. Their risk of failure is high. It is impossible to predict when or if any of our drug candidates will prove effective or safe in humans or will receive marketing approval. If our drug candidates are associated with undesirable side effects or have characteristics that are unexpected, we may need to abandon their development or limit development to certain uses or subpopulations in which the undesirable side effects or other characteristics are less prevalent, less severe or more acceptable from a risk-benefit perspective. For example, we have modified our informed consent form and advised patients already enrolled in our clinical trials of the potential for worsening of pre-existing cataracts as a result of treatment with selinexor. Also, even though selinexor has generally been well-tolerated by patients in our Phase 1 and Phase 2 clinical trials to date, in some cases there were adverse events, some of which were serious. The most common drug-related adverse events, or AEs, were gastrointestinal, such as nausea, anorexia, diarrhea and vomiting, and fatigue. These side effects were generally mild or moderate in severity. The most common AEs that were Grade 3 or Grade 4, meaning they were more than mild or moderate in severity, were thrombocytopenia, or low count of platelets in the blood, and neutropenia, or low neutrophil counts. We also noted an increase in the rates of sepsis in patients with AML who received high doses of selinexor, typically 100mg or higher. A small percentage of patients have withdrawn from our clinical trials as a result of AEs. A small percentage of patients across our clinical trials have experienced serious adverse events, or SAEs, deemed by us and the clinical investigator to be related to selinexor. SAEs generally refer to AEs that result in death, are life threatening, require hospitalization or prolonging of hospitalization, or cause a significant and permanent disruption of normal life functions, congenital anomalies or birth defects, or require intervention to prevent such an outcome.

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As a result of these AEs or further safety or toxicity issues that we may experience in our clinical trials in the future, we may not receive approval to market any drug candidates, which could prevent us from ever generating revenue from the sale of drugs or achieving profitability. Results of our trials could reveal an unacceptably high severity and prevalence of side effects. In such an event, our trials could be suspended or terminated and the FDA or comparable foreign regulatory authorities could order us to cease further development of or deny approval of our drug candidates for any or all targeted indications. Many compounds that initially showed promise in early-stage trials for treating cancer or other diseases have later been found to cause side effects that prevented further development of the compound.

The FDA or non-U.S. regulatory authorities may disagree with our and/or our clinical trial investigators’ interpretation of data from clinical trials in determining if serious adverse or unacceptable side effects are drug-related.

We, and our clinical trial investigators, currently determine if serious adverse or unacceptable side effects are drug-related. The FDA or non-U.S. regulatory authorities may disagree with our or our clinical trial investigators’ interpretation of data from clinical trials and the conclusion by us or our clinical trial investigators that a serious adverse effect or unacceptable side effect was not drug-related. The FDA or non-U.S. regulatory authorities may require more information, including additional preclinical or clinical data to support approval, which may cause us to incur additional expenses, delay or prevent the approval of one of our drug candidates, and/or delay or cause us to change our commercialization plans, or we may decide to abandon the development or commercialization of the drug candidate altogether.

We may expend our limited resources to pursue a particular drug candidate or indication and fail to capitalize on drug candidates or indications that may be more profitable or for which there is a greater likelihood of success.

Because we have limited financial and managerial resources, we focus on research programs and drug candidates that we identify for specific indications. As a result, we may forego or delay pursuit of opportunities with other drug candidates or for other indications that later prove to have greater commercial potential. Our resource allocation decisions may cause us to fail to capitalize on viable commercial drugs or profitable market opportunities. Our spending on current and future research and development programs and drug candidates for specific indications may not yield any commercially-viable drugs. If we do not accurately evaluate the commercial potential or target market for a particular drug candidate, we may relinquish valuable rights to that drug candidate through collaboration, licensing or other royalty arrangements in cases in which it would have been more advantageous for us to retain sole development and commercialization rights to such drug candidate.

Even if any of our drug candidates receives marketing approval, such drug may fail to achieve the degree of market acceptance by physicians, patients, third-party payors and others in the medical community necessary for commercial success.

If any of our drug candidates receive marketing approval, it may nonetheless fail to gain sufficient market acceptance by physicians, patients, third-party payors and others in the medical community. For example, current cancer treatments like chemotherapy and radiation therapy are well-established in the medical community, and doctors may continue to rely on these treatments. If our drug candidates do not achieve an adequate level of acceptance, we may not generate significant revenues from sales of drugs and we may not become profitable. The degree of market acceptance of our drug candidates, if approved for commercial sale, will depend on a number of factors, including:

• efficacy and potential advantages compared to alternative treatments;

• the ability to offer our drugs for sale at competitive prices;

• convenience and ease of administration compared to alternative treatments;

• the willingness of the target patient population to try new therapies and of physicians to prescribe these therapies;

• the strength of marketing and distribution support;

• sufficient third-party coverage or reimbursement;

• the prevalence and severity of any side effects;

• any restrictions on the use of our drugs together with other medications; and

• inability of certain types of patients to take our drugs.

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If, in the future, we are unable to establish sales and marketing capabilities or enter into agreements with third parties to sell and market our drug candidates, we may not be successful in commercializing our drug candidates if and when they are approved.

We do not have a sales or marketing infrastructure and have no experience in the sale or marketing of pharmaceutical drugs. To date, we have not entered into a strategic collaboration that provides us with access to a collaborator’s resources in selling or marketing drugs. To achieve commercial success for any approved drug for which sales and marketing is not the responsibility of any strategic collaborator that we may have in the future, we must either develop a sales and marketing organization or outsource these functions to other third parties. In the future, we may choose to build a sales and marketing infrastructure to market or co-promote some of our drug candidates if and when they are approved, or enter into collaborations with respect to the sale and marketing of our drug candidates. We currently intend to establish a corporate infrastructure to enable us to market selinexor in North America and Western Europe.

There are risks involved with both establishing our own sales and marketing capabilities and entering into arrangements with third parties to perform these services. For example, recruiting and training a sales force is expensive and time-consuming and could delay any commercial launch of a drug candidate. If the commercial launch of a drug candidate for which we recruit a sales force and establish marketing capabilities is delayed or does not occur for any reason, we would have prematurely or unnecessarily incurred these commercialization expenses. This may be costly, and our investment would be lost if we cannot retain or reposition our sales and marketing personnel.

Factors that may inhibit our efforts to commercialize our drugs on our own include:

• our inability to recruit and retain adequate numbers of effective sales and marketing personnel;

• the inability of sales personnel to obtain access to physicians or persuade adequate numbers of physicians to prescribe any future drugs;

• the lack of complementary drugs to be offered by sales personnel, which may put us at a competitive disadvantage relative to companies with more extensive drug lines;

• unforeseen costs and expenses associated with creating an independent sales and marketing organization; and

• inability to obtain sufficient coverage and reimbursement from third-party payors and governmental agencies.

If we enter into arrangements with third parties to perform sales and marketing services, our revenues from the sale of drug or the profitability of these revenues to us are likely to be lower than if we were to market and sell any drugs that we develop ourselves. In addition, we may not be successful in entering into arrangements with third parties to sell and market our drug candidates or may be unable to do so on terms that are favorable to us. We likely will have little control over such third parties, and any of them may fail to devote the necessary resources and attention to sell and market our drugs effectively. If we do not establish sales and marketing capabilities successfully, either on our own or in collaboration with third parties, we will not be successful in commercializing our drug candidates.

We face substantial competition, which may result in others discovering, developing or commercializing drugs before or more successfully than we do.

The discovery, development and commercialization of new drugs is highly competitive. We face competition with respect to our current drug candidates, and will face competition with respect to any drug candidates that we may seek to discover and develop or commercialize in the future, from major pharmaceutical companies, specialty pharmaceutical companies and biotechnology companies worldwide. There are a number of major pharmaceutical, specialty pharmaceutical and biotechnology companies that currently market and sell drugs or are pursuing the development of drugs for the treatment of cancer and the other disease indications for which we are developing our drug candidates, although we believe that to date, none of these competitive drugs and therapies currently in development are based on scientific approaches that are the same as our approach. Potential competitors also include academic institutions and governmental agencies and public and private research institutions.

We are initially focused on developing our current drug candidates for the treatment of cancer. There are a variety of available therapies marketed for cancer. In many cases, cancer drugs are administered in combination to enhance efficacy. Some of these drugs are branded and subject to patent protection, and others are available on a generic basis. Many of these approved drugs are well-established therapies and are widely accepted by physicians, patients and third-party payors. Insurers and other third-party payors may also encourage the use of generic drugs. We expect that if our drug candidates are approved, they will be priced at a significant premium over competitive generic drugs. This may make it difficult for us to achieve our business strategy of using our drug candidates in combination with existing therapies or replacing existing therapies with our drug candidates.

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Our competitors may develop drugs that are more effective, safer, more convenient or less costly than any that we are developing or that would render our drug candidates obsolete or non-competitive. Our competitors may also obtain marketing approval from the FDA or other regulatory authorities for their drugs more rapidly than we may obtain approval for ours, which could result in our competitors establishing a strong market position before we are able to enter the market.

Many of our competitors have significantly greater financial resources and expertise in research and development, manufacturing, preclinical studies, conducting clinical trials, obtaining regulatory approvals and marketing approved drugs than we do. Mergers and acquisitions in the pharmaceutical and biotechnology industries may result in even more resources being concentrated among a smaller number of our competitors. Smaller and other early-stage companies may also prove to be significant competitors, particularly through collaborative arrangements with large and established companies. These third parties compete with us in recruiting and retaining qualified scientific and management personnel, establishing clinical trial sites and patient registration for clinical trials, as well as in acquiring technologies complementary to, or that may be necessary for, our programs.

Even if we are able to commercialize any drug candidates, the drugs may not receive coverage or may become subject to unfavorable pricing regulations, third-party reimbursement practices or healthcare reform initiatives, all of which would harm our business.

The legislation and regulations that govern marketing approvals, pricing and reimbursement for new drug products vary widely from country to country. Some countries require approval of the sale price of a drug before it can be marketed. In many countries, the pricing review period begins after marketing or drug licensing approval is granted. In some foreign markets, prescription pharmaceutical pricing remains subject to continuing governmental control even after initial approval is granted. In the United States, approval and reimbursement decisions are not linked directly, but there is increasing scrutiny from the Congress and regulatory authorities of the pricing of pharmaceutical products. As a result, we might obtain marketing approval for a drug in a particular country, but then be subject to price regulations that delay our commercial launch of the drug, possibly for lengthy time periods, and negatively impact the revenues we are able to generate from the sale of the drug in that country. Adverse pricing limitations may hinder our ability to recoup our investment in one or more drug candidates, even if our drug candidates obtain marketing approval.

Significant uncertainty exists as to the coverage and reimbursement status of our product candidates for which we seek regulatory approval. Our ability to commercialize any drugs successfully will depend, in part, on the extent to which reimbursement for these drugs and related treatments will be available from government health administration authorities, private health insurers and other organizations. Government authorities and third-party payors, such as private health insurers and health maintenance organizations, decide which medications they will pay for and establish reimbursement levels. Obtaining and maintaining adequate reimbursement for our product candidates, if approved, may be difficult. Moreover, the process for determining whether a third-party payor will provide coverage for a product may be separate from the process for setting the price of a product or for establishing the reimbursement rate that such a payor will pay for the product. Further, one payor’s determination to provide coverage for a product does not assure that other payors will also provide coverage and reimbursement for our products, if they are approved, by third-party payors.

A primary trend in the healthcare industry in the United States and elsewhere is cost containment. Government authorities and third-party payors have attempted to control costs by limiting coverage and the amount of reimbursement for particular medications. Increasingly, third-party payors are requiring that drug companies provide them with predetermined discounts from list prices and are challenging the prices charged for medical products. Third-party payors may also seek, with respect to an approved product, additional clinical evidence that goes beyond the data required to obtain marketing approval. They may require such evidence to demonstrate clinical benefits and value in specific patient populations or they may call for costly pharmaceutical studies to justify coverage and reimbursement or the level of reimbursement relative to other therapies before covering our products. Accordingly, we cannot be sure that reimbursement will be available for any drug that we commercialize and, if reimbursement is available, we cannot be sure as to the level of reimbursement and whether it will be adequate. Coverage and reimbursement may impact the demand for, or the price of, any drug candidate for which we obtain marketing approval. If reimbursement is not available or is available only at limited levels, we may not be able to successfully commercialize any drug candidate for which we obtain marketing approval.

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There may be significant delays in obtaining reimbursement for newly-approved drugs, and coverage may be more limited than the indications for which the drug is approved by the FDA or comparable regulatory authorities outside of the United States. Moreover, eligibility for reimbursement does not imply that any drug will be paid for in all cases or at a rate that covers our costs, including research, development, manufacture, sale and distribution. Interim reimbursement levels for new drugs, if applicable, may also not be sufficient to cover our costs and may not be made permanent. Reimbursement rates may vary according to the use of the drug and the clinical setting in which it is used, may be based on reimbursement levels already set for lower cost drugs and may be incorporated into existing payments for other services. Net prices for drugs may be reduced by mandatory discounts or rebates required by government healthcare programs or private payors and by any future relaxation of laws that presently restrict imports of drugs from countries where they may be sold at lower prices than in the United States. Third-party payors often rely upon Medicare coverage policy and payment limitations in setting their own reimbursement policies. Our inability to promptly obtain coverage and profitable payment rates from both government-funded and private payors for any approved drugs that we develop could have a material adverse effect on our operating results, our ability to raise capital needed to commercialize drugs and our overall financial condition.

Product liability lawsuits against us could cause us to incur substantial liabilities and to limit commercialization of any drugs that we may develop.

We face an inherent risk of product liability exposure related to the testing of our drug candidates in human clinical trials and will face an even greater risk if we commercially sell any drugs that we may develop. If we cannot successfully defend ourselves against claims that our drug candidates or drugs caused injuries, we will incur substantial liabilities. Regardless of merit or eventual outcome, liability claims may result in:

• decreased demand for any drug candidates or drugs that we may develop;

• injury to our reputation and significant negative media attention;

• withdrawal of clinical trial participants;

• significant costs to defend the related litigation;

• substantial monetary awards to trial participants or patients;

• loss of revenue;

• reduced resources of our management to pursue our business strategy; and

• the inability to commercialize any drugs that we may develop.

We currently hold clinical trial liability insurance coverage, but that coverage may not be adequate to cover any and all liabilities that we may incur. We would need to increase our insurance coverage when we begin the commercialization of our drug candidates, if ever. Insurance coverage is increasingly expensive. We may not be able to maintain insurance coverage at a reasonable cost or in an amount adequate to satisfy any liability that may arise.

Verdinexor (KPT-335) is our clinical drug candidate for the treatment of pet dogs with newly-diagnosed and first time relapse lymphomas. If the results of our clinical trials of verdinexor are not viewed positively or verdinexor is not approved by the FDA, this may raise safety and efficacy concerns for selinexor, as the anti-cancer activity and adverse event profile of verdinexor in dogs with lymphomas provided support for our decision to move selinexor into Phase 1 clinical trials.

As part of the drug discovery and development process, we have used spontaneously occurring pet dog cancers as a surrogate model for human malignancies. Dog lymphomas respond to chemotherapy in a manner similar to their human counterparts (human non-Hodgkin’s lymphomas) and display a comparable genetic profile. The anti-cancer activity of our drug candidate verdinexor (KPT-335) in a Phase 1 clinical trial in dogs with certain lymphomas provided support for our decision to move selinexor, our closely-related human drug candidate, into Phase 1 clinical trials. We conducted a Phase 2b clinical trial of verdinexor in dogs with newly-diagnosed or first time relapse lymphomas. We have received a Minor Use / Minor Species, or MUMS, designation from the Center for Veterinary Medicine of the FDA for the treatment of newly-diagnosed or after first relapse lymphomas in dogs with verdinexor. Our Phase 2b clinical trial was intended to support regulatory approval under the MUMS designation. We submitted and the FDA accepted the safety and effectiveness sections of a NADA for verdinexor. If verdinexor fails to shows adequate safety or efficacy or is not otherwise viewed positively or if verdinexor is not otherwise approved by the FDA for the treatment of lymphomas in dogs, this may raise questions regarding selinexor because we have used dog cancers as a surrogate model for human malignancies. In such an event, verdinexor’s clinical trial results may cause the FDA or non-U.S. regulatory authorities to require more information, including additional preclinical or clinical data to support approval of selinexor. If the results of the Phase 2b clinical trial of verdinexor fail to demonstrate safety and efficacy to the satisfaction of the FDA or are not otherwise viewed positively, we may incur additional costs or experience delays in completing, or ultimately be unable to complete, the development and commercialization of verdinexor. In such an event, we also may not be able to realize our potential to generate revenue from the commercialization of verdinexor, either on our own or with a collaborator.

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The business that we conduct outside the United States may be adversely affected by international risk and uncertainties.

Although our operations are based in the United States, we conduct business outside the United States and expect to continue to do so in the future. For instance, many of the sites at which our clinical trials are being conducted are located outside the United States. In addition, we plan to seek approvals to sell our products in foreign countries. Any business that we conduct outside the United States will be subject to additional risks that may materially adversely affect our ability to conduct business in international markets, including:

• potentially reduced protection for intellectual property rights;

• the potential for so-called parallel importing, which is what happens when a local seller, faced with high or higher local prices, opts to import goods from a foreign market (with low or lower prices) rather than buying them locally;

• unexpected changes in tariffs, trade barriers and regulatory requirements;

• economic weakness, including inflation, or political instability in particular foreign economies and markets;

• workforce uncertainty in countries where labor unrest is more common than in the United States;

• production shortages resulting from any events affecting a product candidate and/or finished drug product supply or manufacturing capabilities abroad;

• business interruptions resulting from geo-political actions, including war and terrorism, or natural disasters, including earthquakes, hurricanes, typhoons, floods and fires; and

• failure to comply with Office of Foreign Asset Control rules and regulations and the Foreign Corrupt Practices Act, or FCPA.

Risks Related to Our Financial Position and Need for Additional Capital

We have incurred significant losses since inception. We expect to incur losses for the foreseeable future and may never achieve or maintain profitability.

Since inception, we have incurred significant operating losses. Our net loss was $30.2 million for the three months ended June 30, 2016. As of June 30, 2016, we had an accumulated deficit of $313.7 million. We have not generated any revenue to date from sales of any drugs and have financed our operations principally through sales of equity in private placements, our initial public offering, two follow-on offerings of our common stock, and an “at-the-market” offering that we commenced in December 2015 and pursuant to which we may sell additional shares of our common stock. We have devoted substantially all of our efforts to research and development. Our lead drug candidate, oral selinexor (KPT-330), as well as verdinexor (KPT-335), KPT-8602 and KPT-9274, are in clinical development and our other drug candidates for the treatment of human disease are in preclinical development. As a result, we expect that it will be several years, if ever, before we have a drug candidate ready for commercialization for the treatment of human disease. We expect to continue to incur significant expenses and increasing operating losses for the foreseeable future. The net losses we incur may fluctuate significantly from quarter to quarter. We anticipate that our expenses will increase substantially if and as we:

• continue our research and preclinical and clinical development of our drug candidates;

• identify additional drug candidates;

• initiate additional clinical trials for our drug candidates;

• seek marketing approvals for any of our drug candidates that successfully complete clinical trials;

• ultimately establish sales, marketing, manufacturing and distribution infrastructure to commercialize any drugs for which we may obtain marketing approval;

• maintain, expand and protect our intellectual property portfolio;

• hire additional clinical, quality control and scientific personnel;

• acquire or in-license other drugs and technologies; and

• add operational, financial and management information systems and personnel, including personnel to support our drug development, any future commercialization efforts and our operations as a public company.

To become and remain profitable, we must develop and eventually commercialize a drug or drugs with significant market potential, either on our own or with a collaborator. This will require us to be successful in a range of challenging activities, including completing preclinical studies and clinical trials of our drug candidates, obtaining marketing approval for these drug candidates,

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manufacturing, marketing and selling those drugs for which we may obtain marketing approval and establishing and managing any collaborations for the development, marketing and/or commercialization of our drug candidates. We may never succeed in these activities and, even if we do, may never generate revenues that are significant or large enough to achieve profitability. If we do achieve profitability, we may not be able to sustain or increase profitability on a quarterly or annual basis. Our failure to become and remain profitable would decrease the value of the company and could impair our ability to raise capital, maintain our research and development efforts, expand our business and/or continue our operations. A decline in the value of our company could also cause our stockholders to lose all or part of their investment.

Our short operating history may make it difficult for stockholders to evaluate the success of our business to date and to assess our future viability.

We are an early-stage company. We were incorporated in 2008 and commenced operations in 2009. Our operations to date have been limited to organizing and staffing our company, business planning, raising capital, developing our platform, identifying potential drug candidates and conducting preclinical studies and early-stage clinical trials of our drug candidates. Our lead drug candidate is currently in multiple Phase 1 and Phase 2 clinical trials and all of our other drug candidates for the treatment of human disease are in early clinical development or preclinical development. We have not yet demonstrated our ability to successfully complete any late-stage clinical trials in humans, including large-scale clinical trials, obtain marketing approvals, manufacture a commercial scale drug, or arrange for a third party to do so on our behalf, or conduct sales and marketing activities necessary for successful drug commercialization. Typically, it takes about six to ten years to develop one new drug from the time it is in Phase 1 clinical trials to when it is commercially available for treating patients. Consequently, any predictions stockholders make about our future success or viability may not be as accurate as they could be if we had a longer operating history.

In addition, as a business with a short operating history, we may encounter unforeseen expenses, difficulties, complications, delays and other known and unknown factors. We will need to transition from a company with a research focus to a company capable of supporting commercial activities. We may not be successful in such a transition.

As we continue to build our business, we expect our financial condition and operating results may fluctuate significantly from quarter to quarter and year to year due to a variety of factors, many of which are beyond our control. Accordingly, stockholders should not rely upon the results of any particular quarterly or annual periods as indications of future operating performance.

We will need substantial additional funding. If we are unable to raise capital when needed, we would be forced to delay, reduce or eliminate our research and drug development programs or commercialization efforts.

We expect our expenses to increase in connection with our ongoing activities, particularly as we continue the clinical trials of, and seek marketing approval for, selinexor and our other drug candidates. In addition, if we obtain marketing approval for any of our drug candidates, we expect to incur significant commercialization expenses related to drug sales, marketing, manufacturing and distribution to the extent that such sales, marketing, manufacturing and distribution are not the responsibility of any collaborator that we may have at such time for any such drug. Furthermore, we will continue to incur additional costs associated with operating as a public company. Accordingly, we will need to obtain substantial additional funding in connection with our continuing operations. If we are unable to raise capital when needed or on attractive terms, we would be forced to delay, reduce or eliminate our research and drug development programs or commercialization efforts.

We expect that our existing cash, cash equivalents, restricted cash and investments will enable us to fund our operating expenses and capital expenditure requirements into the middle of 2018. Our future capital requirements will depend on many factors, including:

• the progress and results of our current and planned clinical trials of selinexor;

• the scope, progress, results and costs of drug discovery, preclinical development, laboratory testing and clinical trials for our other drug candidates;

• the costs, timing and outcome of regulatory review of our drug candidates;

• our ability to establish and maintain collaborations on favorable terms, if at all;

• the success of any collaborations that we may enter into with third parties;

• the extent to which we acquire or in-license other drugs and technologies;

• the costs of future commercialization activities, including drug sales, marketing, manufacturing and distribution, for any of our drug candidates for which we receive marketing approval, to the extent that such sales, marketing, manufacturing and distribution are not the responsibility of any collaborator that we may have at such time;

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• the amount of revenue, if any, received from commercial sales of our drug candidates, should any of our drug candidates receive marketing approval; and

• the costs of preparing, filing and prosecuting patent applications, maintaining and enforcing our intellectual property rights and defending intellectual property-related claims.

Identifying potential drug candidates and conducting preclinical studies and clinical trials is a time-consuming, expensive and uncertain process that takes years to complete, and we may never generate the necessary data or results required to obtain marketing approval and achieve drug sales. In addition, our drug candidates, if approved, may not achieve commercial success. Our commercial revenues, if any, will be derived from sales of drugs that we do not expect to be commercially available for many years, if at all. Accordingly, we will need to continue to rely on additional financing to achieve our business objectives. Adequate additional financing may not be available to us on acceptable terms, or at all. In addition, we may seek additional capital due to favorable market conditions or strategic considerations, even if we believe we have sufficient funds for our current or future operating plans.

Raising additional capital may cause dilution to our stockholders, restrict our operations or require us to relinquish rights to our drug candidates.

Until such time, if ever, as we can generate substantial revenues from the sale of drugs, we expect to finance our cash needs through a combination of equity offerings, debt financings, collaborations, strategic alliances and/or licensing arrangements. We do not have any committed external source of funds. To the extent that we raise additional capital through the sale of equity or convertible debt securities, the ownership interests of stockholders will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect the rights of common stockholders. Debt financing, if available, may involve agreements that include covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends.

If we raise funds through collaborations, strategic alliances or licensing arrangements with third parties, we may have to relinquish valuable rights to our future revenue streams, research programs or drug candidates or to grant licenses on terms that may not be favorable to us. If we are unable to raise additional funds through equity or debt financings when needed, we may be required to delay, limit, reduce or terminate our research and drug development or commercialization efforts or grant rights to develop and market drug candidates that we would otherwise prefer to develop and market ourselves.

Unstable market and economic conditions may have serious adverse consequences on our business, financial condition and stock price.

Global credit and financial markets have experienced extreme disruptions over some of the past several years, including in recent months. Such disruptions have resulted, and could in the future result, in diminished liquidity and credit availability, declines in consumer confidence, declines in economic growth, increases in unemployment rates and uncertainty about economic stability. There can be no assurance that any deterioration in credit and financial markets and confidence in economic conditions will not occur. Our general business strategy may be compromised by economic downturns, a volatile business environment and unpredictable and unstable market conditions. If the equity and credit markets deteriorate, it may make any necessary equity or debt financing more difficult to secure, more costly or more dilutive. Failure to secure any necessary financing in a timely manner and on favorable terms could harm our growth strategy, financial performance and stock price and could require us to delay or abandon plans with respect to our business, including clinical development plans. In addition, there is a risk that one or more of our current service providers, manufacturers or other third parties with which we conduct business may not survive difficult economic times, which could directly affect our ability to attain our operating goals on schedule and on budget.

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Risks Related to Our Dependence on Third Parties

We expect to depend on third parties for certain aspects of the development, marketing and/or commercialization of our drug candidates. If those collaborations are not successful, we may not be able to capitalize on the market potential of these drug candidates.

We intend to seek third-party collaborators for certain aspects of the development, marketing and/or commercialization of our drug candidates. For example, while we currently plan to develop and seek approval of selinexor in North America and Western Europe with respect to the potential approval of selinexor without a collaborator, we anticipate that we will seek to enter into a collaboration for marketing and commercialization of selinexor at the appropriate time in the future for other geographies. In addition, we intend to seek one or more collaborators to aid in the further development, marketing and/or commercialization of our other SINE compounds for inflammatory, autoimmune and/or neurological conditions and viral indications. Our likely collaborators for any collaboration arrangements include large and mid-size pharmaceutical companies, regional and national pharmaceutical companies and biotechnology companies. If we do enter into any such arrangements with any third parties, we will likely have limited control over the amount and timing of resources that our collaborators dedicate to the development, marketing and/or commercialization of our drug candidates. Our ability to generate revenues from these arrangements will depend on our collaborators’ abilities to successfully perform the functions assigned to them in these arrangements.

Collaborations involving our drug candidates pose the following risks to us:

• collaborators have significant discretion in determining the efforts and resources that they will apply to these collaborations;

• collaborators may not pursue development, marketing and/or commercialization of our drug candidates or may elect not to continue or renew development, marketing or commercialization programs based on clinical trial results, changes in the collaborator’s strategic focus or available funding or external factors such as an acquisition that diverts resources or creates competing priorities;

• collaborators may delay clinical trials, provide insufficient funding for a clinical trial program, stop a clinical trial or abandon a drug candidate, repeat or conduct new clinical trials or require a new formulation of a drug candidate for clinical testing;

• collaborators could independently develop, or develop with third parties, drugs that compete directly or indirectly with our drugs or drug candidates if the collaborators believe that competitive drugs are more likely to be successfully developed or can be commercialized under terms that are more economically attractive than ours;

• a collaborator with marketing and distribution rights to one or more drugs may not commit sufficient resources to the marketing and distribution of such drug or drugs;

• collaborators may not properly maintain or defend our intellectual property rights or may use our proprietary information in such a way as to invite litigation that could jeopardize or invalidate our proprietary information or expose us to potential litigation;

• collaborators may infringe the intellectual property rights of third parties, which may expose us to litigation and potential liability;

• disputes may arise between the collaborators and us that result in the delay or termination of the research, development or commercialization of our drugs or drug candidates or that result in costly litigation or arbitration that diverts management’s attention and resources of the company;

• we may lose certain valuable rights under circumstances identified in any collaboration arrangement that we enter into, such as if we undergo a change of control;

• collaborations may be terminated and, if terminated, may result in a need for additional capital to pursue further development, marketing and/or commercialization of the applicable drug candidates;

• collaborators may learn about our discoveries and use this knowledge to compete with us in the future; and

• the number and type of our collaborations could adversely affect our attractiveness to future collaborators or acquirers.

Collaboration agreements may not lead to development or commercialization of drug candidates in the most efficient manner, or at all.

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If we are not able to establish collaborations as we currently plan, we may have to alter our development and commercialization plans.

Our drug development programs and the potential commercialization of our drug candidates will require substantial additional cash to fund expenses. As noted above, we expect to collaborate with pharmaceutical and biotechnology companies for the development and/or commercialization of our drug candidates.

We face significant competition in seeking appropriate collaborators. Whether we reach a definitive agreement for a collaboration will depend, among other things, upon our assessment of the collaborator’s resources and expertise, the terms and conditions of the proposed collaboration and the proposed collaborator’s evaluation of a number of factors. Those factors may include the design or results of clinical trials, the likelihood of approval by the FDA or similar regulatory authorities outside of the United States, the potential market for the subject drug candidate, the costs and complexities of manufacturing and delivering such drug candidate to patients, the potential of competing drugs, the existence of uncertainty with respect to our ownership of intellectual property, which can exist if there is a challenge to such ownership without regard to the merits of the challenge, and industry and market conditions generally. The collaborator may also consider alternative drug candidates or technologies for similar indications that may be available to collaborate on and whether such a collaboration could be more attractive than the one with us for our drug candidate.

We may also be restricted under then-existing collaboration agreements from entering into future agreements on certain terms with potential collaborators.

Collaborations are complex and time-consuming to negotiate and document. In addition, there have been a significant number of recent business combinations among large pharmaceutical companies that have resulted in a reduced number of potential future collaborators.

We may not be able to negotiate collaborations on a timely basis, on acceptable terms, or at all. If we are unable to do so, we may have to curtail the development of such drug candidate, reduce or delay its development program or one or more of our other development programs, delay its potential commercialization or reduce the scope of any sales or marketing activities, or increase our expenditures and undertake development or commercialization activities at our own expense. If we elect to increase our expenditures to fund development or commercialization activities on our own, we may need to obtain additional capital, which may not be available to us on acceptable terms, or at all. If we do not have sufficient funds, we may not be able to further develop our drug candidates or bring them to market and generate revenue from sales of drugs.

We rely on third parties to conduct our clinical trials and some aspects of our research and preclinical studies, and those third parties may not perform satisfactorily, including failing to meet deadlines for the completion of such trials, research or testing.

We rely on third parties, such as contract research organizations, clinical data management organizations, medical institutions and clinical investigators, to conduct our clinical trials. We currently rely and expect to continue to rely on third parties to conduct some aspects of our research and preclinical studies. Any of these third parties may terminate their engagements with us at any time. If we need to enter into alternative arrangements, it would delay our drug development activities.

Our reliance on these third parties for research and development activities will reduce our control over these activities but will not relieve us of our responsibilities. For example, we will remain responsible for ensuring that each of our clinical trials is conducted in accordance with the general investigational plan and protocols for the trial. Moreover, the FDA requires us to comply with standards, commonly referred to as Good Clinical Practices, for conducting, recording and reporting the results of clinical trials to assure that data and reported results are credible and accurate and that the rights, integrity and confidentiality of trial participants are protected. The European Medicines Agency also requires us to comply with comparable standards. We also are required to register ongoing clinical trials and post the results of completed clinical trials on a government-sponsored database, ClinicalTrials.gov, within certain timeframes. Failure to do so can result in fines, adverse publicity and civil and criminal sanctions.

Furthermore, these third parties may also have relationships with other entities, some of which may be our competitors. If these third parties do not successfully carry out their contractual duties, meet expected deadlines or conduct our clinical trials in accordance with regulatory requirements or our stated protocols, we will not be able to obtain, or may be delayed in obtaining, marketing approvals for our drug candidates and will not be able to, or may be delayed in our efforts to, successfully commercialize our drug candidates.

We also expect to rely on other third parties to store and distribute drug supplies for our clinical trials. Any performance failure on the part of such third parties could delay clinical development or marketing approval of our drug candidates or commercialization of our drugs, producing additional losses and depriving us of potential revenue from sales of drugs.

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We rely on third parties to conduct investigator-sponsored clinical trials of selinexor and our other drug candidates. Any failure by a third party to meet its obligations with respect to the clinical development of our drug candidates may delay or impair our ability to obtain regulatory approval for selinexor and our other drug candidates.

We rely on academic and private non-academic institutions to conduct and sponsor clinical trials relating to selinexor and our other drug candidates. We do not control the design or conduct of the investigator-sponsored trials, and it is possible that the FDA or non-U.S. regulatory authorities will not view these investigator-sponsored trials as providing adequate support for future clinical trials, whether controlled by us or third parties, for any one or more reasons, including elements of the design or execution of the trials or safety concerns or other trial results.

Such arrangements will provide us certain information rights with respect to the investigator-sponsored trials, including access to and the ability to use and reference the data, including for our own regulatory filings, resulting from the investigator-sponsored trials. However, we do not have control over the timing and reporting of the data from investigator-sponsored trials, nor do we own the data from the investigator-sponsored trials. If we are unable to confirm or replicate the results from the investigator-sponsored trials or if negative results are obtained, we would likely be further delayed or prevented from advancing further clinical development of our drug candidates. Further, if investigators or institutions breach their obligations with respect to the clinical development of our drug candidates, or if the data proves to be inadequate compared to the first-hand knowledge, we might have gained had the investigator-sponsored trials been sponsored and conducted by us, then our ability to design and conduct any future clinical trials ourselves may be adversely affected.

Additionally, the FDA or non-U.S. regulatory authorities may disagree with the sufficiency of our right of reference to the preclinical, manufacturing or clinical data generated by these investigator-sponsored trials, or our interpretation of preclinical, manufacturing or clinical data from these investigator-sponsored trials. If so, the FDA or other non-U.S. regulatory authorities may require us to obtain and submit additional preclinical, manufacturing, or clinical data before we may initiate our planned trials and/or may not accept such additional data as adequate to initiate our planned trials.

We contract with third parties for the manufacture of our drug candidates for preclinical studies and clinical trials and expect to continue to do so for clinical trials and ultimately for commercialization. This reliance on third parties increases the risk that we will not have sufficient quantities of our drug candidates or drugs or such quantities at an acceptable cost, which could delay, prevent or impair our development or commercialization efforts.

We do not have any manufacturing facilities or personnel. We currently rely, and expect to continue to rely, on third-party manufacturers for the manufacture of our drug candidates for preclinical studies and clinical trials under the guidance of members of our organization. We have engaged third-party manufacturers for drug substance and drug product (fill-and-finish) services. We do not have a long term supply agreement with any of these third-party manufacturers, and we purchase our required drug supplies on a purchase order basis.

We expect to rely on third-party manufacturers or third-party collaborators for the manufacture of our drug candidates for clinical trials and ultimately for commercial supply of any of these drug candidates for which we or any of our future collaborators obtain marketing approval. We may be unable to establish any agreements with third-party manufacturers or to do so on acceptable terms. Even if we are able to establish agreements with third-party manufacturers, reliance on third-party manufacturers entails additional risks, including:

• reliance on the third party for regulatory compliance and quality assurance;

• the possible breach of the manufacturing agreement by the third party;

• the possible failure of the third party to manufacture our drug candidate according to our specifications;

• the possible failure of the third party to manufacture our drug candidate according to our schedule, or at all;

• the possible misappropriation or disclosure by the third party or others of our proprietary information, including our trade secrets and know-how; and

• the possible termination or nonrenewal of the agreement by the third party at a time that is costly or inconvenient for us.

Third-party manufacturers may not be able to comply with cGMP regulations or similar regulatory requirements outside of the United States. Our failure, or the failure of our third-party manufacturers, to comply with applicable regulations could result in sanctions being imposed on us, including fines, injunctions, civil penalties, delays, suspension or withdrawal of approvals, license revocation, seizures or recalls of drug candidates or drugs, operating restrictions and criminal prosecutions, any of which could significantly and adversely affect supplies of our drugs and harm our business and results of operations.

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Any drugs that we may develop may compete with other drug candidates and drugs for access to manufacturing facilities. There are a limited number of manufacturers that operate under cGMP regulations and that might be capable of manufacturing for us.

Any performance failure on the part of our existing or future manufacturers could delay clinical development or marketing approval. If our current contract manufacturers cannot perform as agreed, we may be required to replace those manufacturers. Although we believe that there are several potential alternative manufacturers who could manufacture our drug candidates, we may incur added costs and delays in identifying and qualifying any such replacement.

Our current and anticipated future dependence upon others for the manufacture of our drug candidates or drugs may adversely affect our future profit margins and our ability to commercialize any drugs that receive marketing approval on a timely and competitive basis.

Risks Related to Our Intellectual Property

If we are unable to obtain and maintain patent protection for our drug candidates and other discoveries, or if the scope of the patent protection obtained is not sufficiently broad, our competitors could develop and commercialize drugs and other discoveries similar or identical to ours, and our ability to successfully commercialize our drug candidates and other discoveries may be adversely affected.

Our success depends in large part on our ability to obtain and maintain patent protection in the United States and other countries with respect to our proprietary drug candidates and other discoveries. We seek to protect our proprietary position by filing patent applications in the United States and abroad related to our novel drug candidates and other discoveries that are important to our business. To date, 16 patents have issued that relate to XPO1 inhibitors, including composition of matter patents for selinexor, verdinexor and KPT-350 in the United States, and their use in targeted therapeutics. We cannot be certain that any other patents will issue with claims that cover any of our key drug candidates or other discoveries or drug candidates.

The patent prosecution process is expensive and time-consuming, and we may not be able to file and prosecute all necessary or desirable patent applications at a reasonable cost or in a timely manner. It is also possible that we will fail to identify patentable aspects of our research and development output before it is too late to obtain patent protection.

The patent position of biotechnology and pharmaceutical companies generally is highly uncertain, involves complex legal and factual questions and has in recent years been the subject of much litigation. As a result, the issuance, scope, validity, enforceability and commercial value of our patent rights are highly uncertain. Our pending and future patent applications may not result in patents being issued which protect our drug candidates or other discoveries, or which effectively prevent others from commercializing competitive drugs and discoveries. Changes in either the patent laws or interpretation of the patent laws in the United States and other countries may diminish the value of our patents or narrow the scope of our patent protection.

The laws of foreign countries may not protect our rights to the same extent as the laws of the United States. For example, in some foreign jurisdictions, our ability to secure patents based on our filings in the United States may depend, in part, on our ability to timely obtain assignment of rights to the invention from the employees and consultants who invented the technology. Publications of discoveries in the scientific literature often lag behind the actual discoveries, and patent applications in the United States and other jurisdictions are typically not published until 18 months after filing, or in some cases not at all. Therefore, we cannot be certain that we were the first to make the inventions claimed in our patent or pending patent applications, or that we were the first to file for patent protection of such inventions.

Assuming the other requirements for patentability are met, prior to March 2013, in the United States, the first to invent the claimed invention was entitled to the patent, while outside of the United States, the first to file a patent application is entitled to the patent. In March 2013, the United States transitioned to a first-inventor-to-file system in which, assuming the other requirements for patentability are met, the first inventor to file a patent application is entitled to the patent. We may be subject to a third-party preissuance submission of prior art to the U.S. Patent and Trademark Office, or become involved in opposition, derivation, revocation, reexamination, or post-grant or inter partes review or interference proceedings challenging our patent rights or the patent rights of others. An adverse determination in any such submission, proceeding or litigation could reduce the scope of, or invalidate, our patent rights, allow third parties to commercialize our discoveries or drugs and compete directly with us, without payment to us, or result in our inability to manufacture or commercialize drugs without infringing third-party patent rights.

Even if our patent applications issue as patents, they may not issue in a form that will provide us with any meaningful protection, prevent competitors from competing with us or otherwise provide us with any competitive advantage. Our competitors may be able to circumvent our patents by developing similar or alternative discoveries or drugs in a non-infringing manner.

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The issuance of a patent is not conclusive as to its inventorship, scope, validity or enforceability, and our patents may be challenged in the courts or patent offices in the United States and abroad. Such challenges may result in loss of exclusivity or in patent claims being narrowed, invalidated or held unenforceable, which could limit our ability to stop others from using or commercializing similar or identical discoveries and drugs, or limit the duration of the patent protection of our discoveries and drug candidates. Given the amount of time required for the development, testing and regulatory review of new drug candidates, patents protecting such candidates might expire before or shortly after such candidates are commercialized. As a result, our patent portfolio may not provide us with sufficient rights to exclude others from commercializing drugs similar or identical to ours.

We may become involved in lawsuits to protect or enforce our patents and other intellectual property rights, which could be expensive, time-consuming and unsuccessful.

Competitors or commercial supply companies or others may infringe our patents and other intellectual property rights. For example, we are aware of a third party selling a version of our lead product candidate for research purposes, which may infringe our intellectual property rights. To counter such infringement, we may advise such companies of our intellectual property rights, including, in some cases, intellectual property rights that provide protection for our lead product candidates, and demand that they stop infringing those rights. Such demand may provide such companies the opportunity to challenge the validity of certain of our intellectual property rights, or the opportunity to seek a finding that their activities do not infringe our intellectual property rights. We may also be required to file infringement actions, which can be expensive and time-consuming. In an infringement proceeding, a defendant may assert and a court may agree with a defendant that a patent of ours is invalid or unenforceable, or may refuse to stop the other party from using the intellectual property at issue. An adverse result in any litigation could put one or more of our patents at risk of being invalidated or interpreted narrowly. Furthermore, because of the substantial amount of discovery required in connection with intellectual property litigation, there is a risk that some of our confidential information could be compromised by disclosure during this type of litigation.

Third parties may initiate legal proceedings alleging that we are infringing their intellectual property rights, the outcome of which would be uncertain and could have a material adverse effect on the success of our business.

Our commercial success depends upon our ability and the ability of any future collaborators that we may have to develop, manufacture, market and sell our drug candidates and use our proprietary technologies without infringing the proprietary rights of third parties. We may become party to, or threatened with, future adversarial proceedings or litigation regarding intellectual property rights with respect to our drug candidates and technology, including interference proceedings before the U.S. Patent and Trademark Office. Third parties may assert infringement claims against us based on existing patents or patents that may be granted in the future. No litigation asserting such infringement claims is currently pending against us, and we have not been found by a court of competent jurisdiction to have infringed a third party’s intellectual property rights; however, if we are found to infringe a third party’s intellectual property rights, we could be required to obtain a license from such third party to continue developing and marketing our drug candidates and using our technology. However, we may not be able to obtain any required license on commercially reasonable terms, or at all. Even if we were able to obtain a license, it could be non-exclusive, thereby giving our competitors access to the same intellectual property licensed to us. We could be forced, including by court order, to cease commercializing the infringing intellectual property or drug or to cease using the infringing technology. In addition, we could be found liable for monetary damages. A finding of infringement could prevent us from commercializing our drug candidates or force us to cease some of our business operations, which could materially harm our business. Claims that we have misappropriated the confidential information or trade secrets of third parties could have a similar negative impact on our business.

We may be subject to claims that our employees have wrongfully used or disclosed alleged trade secrets of their former employers.

Many of our employees were previously employed at universities or other biotechnology or pharmaceutical companies, including our competitors or potential competitors. Although we try to ensure that our employees do not use the proprietary information or know-how of others in their work for us, we may be subject to claims that we or these employees have used or disclosed intellectual property, including trade secrets or other proprietary information, of any such employee’s former employer. Although we have no knowledge of any such claims being alleged to date, if such claims were to arise, litigation may be necessary to defend against any such claims. If we fail in defending any such claims, in addition to paying monetary damages, we may lose valuable intellectual property rights or personnel. Even if we are successful in defending against such claims, litigation could result in substantial costs and be a distraction to management.

Intellectual property litigation could cause us to spend substantial resources and distract our personnel from their normal responsibilities.

Even if resolved in our favor, litigation or other legal proceedings relating to intellectual property claims may cause us to incur significant expenses, and could distract our technical and management personnel from their normal responsibilities. In addition, there

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could be public announcements of the results of hearings, motions or other interim proceedings or developments and if securities analysts or investors perceive these results to be negative, it could have a material adverse effect on the price of our common stock. Such litigation or proceedings could substantially increase our operating losses and reduce the resources available for development activities or any future sales, marketing or distribution activities. We may not have sufficient financial or other resources to adequately conduct such litigation or proceedings. Some of our competitors may be able to sustain the costs of such litigation or proceedings more effectively than we can because of their greater financial resources. Uncertainties resulting from the initiation and continuation of patent litigation or other proceedings could have a material adverse effect on our ability to compete in the marketplace.

Obtaining and maintaining our patent protection depends on compliance with various procedural, documentary, fee payment and other requirements imposed by governmental patent agencies, and our patent protection could be reduced or eliminated for non-compliance with these requirements.

Periodic maintenance fees, renewal fees, annuity fees and various other governmental fees on patents and/or applications will be due to the United States Patent and Trademark Office, or USPTO, and various foreign patent offices at various points over the lifetime of the patents and/or applications. We have systems in place to remind us to pay these fees, and we rely on our outside counsel to pay these fees when due. Additionally, the USPTO and various foreign patent offices require compliance with a number of procedural, documentary, fee payment and other similar provisions during the patent application process. We employ reputable law firms and other professionals to help us comply with such provisions, and in many cases, an inadvertent lapse can be cured by payment of a late fee or by other means in accordance with rules applicable to the particular jurisdiction. However, there are situations in which non-compliance can result in abandonment or lapse of the patent or patent application, resulting in partial or complete loss of patent rights in the relevant jurisdiction. If such an event were to occur, it could have a material adverse effect on our business.

If we do not successfully extend the term of patents covering our drug candidates under the Hatch-Waxman Amendments and similar foreign legislation, our business may be materially harmed.

Depending upon the timing, duration and conditions of FDA marketing approval, if any, of our drug candidates, one or more of our U.S. patents may be eligible for patent term extension under the Drug Price Competition and Patent Term Restoration Act of 1984, referred to as the Hatch-Waxman Amendments. The Hatch-Waxman Amendments permit a patent term extension of up to five years for one patent covering an approved product as compensation for effective patent term lost during product development and the FDA regulatory review process. However, we may not receive an extension if we fail to apply within applicable deadlines, fail to apply prior to expiration of relevant patents or otherwise fail to satisfy applicable requirements. Moreover, the length of the extension could be less than we request. The total patent term, including the extension period, may not exceed 14 years following FDA approval. Accordingly, the length of the extension, or the ability to even obtain an extension, depends on many factors.

In the United States, only a single patent can be extended for each qualifying FDA approval, and any patent can be extended only once and only for a single product. Laws governing analogous patent term extensions in foreign jurisdictions vary widely, as do laws governing the ability to obtain multiple patents from a single patent family. Because both selinexor and verdinexor are protected by a single family of patents and applications, we may not be able to secure patent term extensions for both of these drug candidates in all jurisdictions where these drug candidates are approved, if ever.

If we are unable to obtain a patent term extension for a drug candidate or the term of any such extension is less than we request, the period during which we can enforce our patent rights for that drug candidate, if any, in that jurisdiction will be shortened and our competitors may obtain approval to market competing products sooner. As a result, our revenue could be materially reduced.

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If we are unable to protect the confidentiality of our trade secrets, our business and competitive position would be harmed.

In addition to seeking patents for our drug candidates and other discoveries, we also rely on trade secrets, including unpatented know-how, technology and other proprietary information, to maintain our competitive position. We seek to protect these trade secrets, in part, by entering into non-disclosure and confidentiality agreements with parties who have access to them, such as our employees, outside scientific collaborators, contract research organizations, contract manufacturers, consultants, advisors and other third parties. We also enter into confidentiality and invention or patent assignment agreements with our employees and consultants. Despite these efforts, any of these parties may breach the agreements and disclose our proprietary information, including our trade secrets, and we may not be able to obtain adequate remedies for such breaches. To the extent that we are unable to timely enter into confidentiality and invention or patent assignment agreements with our employees and consultants, our ability to protect our business through trade secrets and patents may be harmed. Enforcing a claim that a party illegally disclosed or misappropriated a trade secret is difficult, expensive and time-consuming, and the outcome is unpredictable. In addition, some courts inside and outside of the United States are less willing or unwilling to protect trade secrets. If any of our trade secrets were to be lawfully obtained or independently developed by a competitor, we would have no right to prevent them from using that technology or information to compete with us. If any of our trade secrets were to be disclosed to or independently developed by a competitor, our competitive position would be harmed.

Not all of our trademarks are registered. Failure to secure those registrations could adversely affect our business.

Three of our trademarks are registered in the United States. We also have seven pending intent-to-use applications that we filed in 2014 and 2015, which have been allowed, meaning that we can perfect our registrations when we have commenced use in commerce. Outside the United States, we have five registrations in the European Union, and we filed two applications each in fourteen other jurisdictions. Several of those have proceeded to registration. If we do not secure registrations for our trademarks, we may encounter more difficulty in enforcing them against third parties than we otherwise would, which could adversely affect our business. During trademark registration proceedings in the United States and foreign jurisdictions, we may receive rejections. Currently, we are addressing one refusal in India. We are given an opportunity to respond to those rejections, but we may not be able to overcome such rejections. In addition, in the USPTO and in comparable agencies in many foreign jurisdictions, third parties are given an opportunity to oppose pending trademark applications and to seek to cancel registered trademarks. Opposition or cancellation proceedings may be filed against our trademarks, and our trademarks may not survive such proceedings.

In addition, any proprietary name we propose to use with our key drug candidates in the United States must be approved by the FDA, regardless of whether we have registered it, or applied to register it, as a trademark. The FDA typically conducts a review of proposed drug names, including an evaluation of potential for confusion with other drug names. If the FDA objects to any of our proposed proprietary drug names for any of our drug candidates, if approved, we may be required to expend significant additional resources in an effort to identify a suitable proprietary drug name that would qualify under applicable trademark laws, not infringe the existing rights of third parties and be acceptable to the FDA.

Risks Related to Regulatory Approval and Marketing of Our Product Candidates Other Legal Compliance Matters

We may not be able to obtain orphan drug exclusivity for our product candidates.

Regulatory authorities in some jurisdictions, including the United States and Europe, may designate drugs and biologics for relatively small patient populations as orphan drugs. Under the Orphan Drug Act, the FDA may designate a product as an orphan drug if it is a drug or biologic intended to treat a rare disease or condition, which is generally defined as a patient population of fewer than 200,000 individuals annually in the United States.

Generally, if a product with an orphan drug designation subsequently receives the first marketing approval for the indication for which it has such designation, the product is entitled to a period of marketing exclusivity, which precludes the EMA or the FDA from approving another marketing application for the same product for that time period. The applicable period is seven years in the United States and ten years in Europe. The European exclusivity period can be reduced to six years if a product no longer meets the criteria for orphan drug designation or if the product is sufficiently profitable so that market exclusivity is no longer justified. Orphan drug exclusivity may be lost if the FDA or EMA determines that the request for designation was materially defective or if the manufacturer is unable to assure sufficient quantity of the product to meet the needs of patients with the rare disease or condition.

Even if we obtain orphan drug exclusivity from the FDA for a product, as we have for selinexor in AML, diffuse large B-cell lymphoma (DLBCL), including Richter’s transformation, and multiple myeloma, that exclusivity may not effectively protect the product from competition because different products can be approved for the same condition. Even after an orphan drug is approved, the FDA can subsequently approve the same product for the same condition if the FDA concludes that the later product is clinically superior in that it is shown to be safer, more effective or makes a major contribution to patient care.

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A fast track designation, grant of priority review status or breakthrough therapy status by the FDA is not assured and, in any event, may not actually lead to a faster development or regulatory review or approval process and, moreover, would not assure FDA approval of our product candidates.

We may be eligible for fast track designation, priority review or breakthrough therapy status for product candidates that we develop. If a product is intended for the treatment of a serious or life-threatening disease or condition and the product demonstrates the potential to address unmet medical needs for this disease or condition, the product sponsor may apply for FDA fast track designation. If a product offers major advances in treatment, the product sponsor may apply for FDA priority review status. Additionally, a product candidate may be designated as a breakthrough therapy if it is intended, either alone or in combination with one or more other drugs, to treat a serious or life-threatening disease or condition and preliminary clinical evidence indicates that the product may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints. The FDA has broad discretion whether or not to grant these designations, so even if we believe a particular product candidate is eligible for such designation or status, the FDA could decide not to grant it. Moreover, even if we do receive such a designation, we may not experience a faster development process, review or approval compared to conventional FDA procedures and there is no assurance that our product candidate will be approved by the FDA.

Even if we complete the necessary preclinical studies and clinical trials, the marketing approval process is expensive, time-consuming and uncertain and may prevent us from obtaining approvals for the commercialization of some or all of our drug candidates. As a result, we cannot predict when or if we, or any collaborators we may have in the future, will obtain marketing approval to commercialize a drug candidate.

The research, testing, manufacturing, labeling, approval, selling, marketing, promotion and distribution of drugs are subject to extensive regulation by the FDA and comparable foreign regulatory authorities, whose laws and regulations may differ from country to country. We are not permitted to market our drug candidates in the United States or in other countries until we, or any collaborators we may have in the future, receive approval of an NDA from the FDA or marketing approval from applicable regulatory authorities outside of the United States. Our drug candidates are in early stages of development and are subject to the risks of failure inherent in drug development. We have not submitted an application for or received marketing approval for any of our drug candidates in the United States or in any other jurisdiction. We have limited experience in conducting and managing the clinical trials necessary to obtain marketing approvals, including FDA approval of an NDA.

The process of obtaining marketing approvals, both in the United States and abroad, is a lengthy, expensive and uncertain process. It may take many years, if approval is obtained at all, and can vary substantially based upon a variety of factors, including the type, complexity and novelty of the drug candidates involved.

In addition, changes in marketing approval policies during the development period, changes in or the enactment or promulgation of additional statutes, regulations or guidance or changes in regulatory review for each submitted drug application, may cause delays in the approval or rejection of an application. Regulatory authorities have substantial discretion in the approval process and may refuse to accept any application or may decide that our data are insufficient for approval and require additional preclinical studies, clinical trials or other studies and testing. In addition, varying interpretations of the data obtained from preclinical studies and clinical trials could delay, limit or prevent marketing approval of a drug candidate. Any marketing approval we, or any collaborators we may have in the future, ultimately obtain may be limited or subject to restrictions or post-approval commitments that render the approved drug not commercially viable.

Any delay in obtaining or failure to obtain required approvals could materially adversely affect our ability or that of any collaborators we may have to generate revenue from the particular drug candidate, which likely would result in significant harm to our financial position and adversely impact our stock price.

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Our failure to obtain marketing approval in foreign jurisdictions would prevent our product candidates from being marketed abroad, and any approval we are granted for our product candidates in the United States would not assure approval of product candidates in foreign jurisdictions.

In order to market and sell our drugs in the European Union and many other jurisdictions, we, and any collaborators we may have in the future, must obtain separate marketing approvals and comply with numerous and varying regulatory requirements. The approval procedure varies among countries and can involve additional testing. The time required to obtain approval may differ substantially from that required to obtain FDA approval. The marketing approval process outside of the United States generally includes all of the risks associated with obtaining FDA approval. In addition, in many countries outside of the United States, it is required that the drug be approved for reimbursement before the drug can be approved for sale in that country. We, and any collaborators we may have in the future, may not obtain approvals from regulatory authorities outside of the United States on a timely basis, if at all. Approval by the FDA does not ensure approval by regulatory authorities in other countries or jurisdictions, and approval by one regulatory authority outside of the United States does not ensure approval by regulatory authorities in other countries or jurisdictions or by the FDA.

Even if we, or any collaborators we may have in the future, obtain marketing approvals for our drug candidates, the terms of approvals and ongoing regulation of our drugs may limit how we, or they, manufacture and market our drugs, which could materially impair our ability to generate revenue.

Once marketing approval has been granted, an approved drug and its manufacturer and marketer are subject to ongoing review and extensive regulation. We, and any collaborators we may have in the future, must therefore comply with requirements concerning advertising and promotion for any of our drug candidates for which we or they obtain marketing approval. Promotional communications with respect to prescription drugs are subject to a variety of legal and regulatory restrictions and must be consistent with the information in the drug’s approved labeling. Thus, we, and any collaborators we may have in the future, may not be able to promote any drugs we develop for indications or uses for which they are not approved.

In addition, manufacturers of approved drugs and those manufacturers’ facilities are required to comply with extensive FDA requirements, including ensuring that quality control and manufacturing procedures conform to cGMPs, which include requirements relating to quality control and quality assurance as well as the corresponding maintenance of records and documentation and reporting requirements. We, our contract manufacturers, our future collaborators and their contract manufacturers could be subject to periodic unannounced inspections by the FDA to monitor and ensure compliance with cGMPs.

Accordingly, assuming we, or our future collaborators, receive marketing approval for one or more of our drug candidates, we, and our future collaborators, and our and their contract manufacturers will continue to expend time, money and effort in all areas of regulatory compliance, including manufacturing, production, product surveillance and quality control.

If we, and our future collaborators, are not able to comply with post-approval regulatory requirements, we, and our future collaborators, could have the marketing approvals for our drugs withdrawn by regulatory authorities and our, or our future collaborators’, ability to market any future drugs could be limited, which could adversely affect our ability to achieve or sustain profitability. Further, the cost of compliance with post-approval regulations may have a negative effect on our operating results and financial condition.

Any of our drug candidates for which we, or our future collaborators, obtain marketing approval in the future could be subject to post-marketing restrictions or withdrawal from the market and we, and our future collaborators, may be subject to substantial penalties if we, or they, fail to comply with regulatory requirements or if we, or they, experience unanticipated problems with our drugs following approval.

Any of our drug candidates for which we, or our future collaborators, obtain marketing approval in the future, as well as the manufacturing processes, post-approval studies and measures, labeling, advertising and promotional activities for such drug, among other things, will be subject to continual requirements of and review by the FDA and other regulatory authorities. These requirements include submissions of safety and other post-marketing information and reports, registration and listing requirements, requirements relating to manufacturing, quality control, quality assurance and corresponding maintenance of records and documents, requirements regarding the distribution of samples to physicians and recordkeeping. Even if marketing approval of a drug candidate is granted, the approval may be subject to limitations on the indicated uses for which the drug may be marketed or to the conditions of approval, including the requirement to implement a Risk Evaluation and Mitigation Strategy, which could include requirements for a restricted distribution system.

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The FDA may also impose requirements for costly post-marketing studies or clinical trials and surveillance to monitor the safety or efficacy of a drug. The FDA and other agencies, including the Department of Justice, or the DOJ, closely regulate and monitor the post-approval marketing and promotion of drugs to ensure that they are manufactured, marketed and distributed only for the approved indications and in accordance with the provisions of the approved labeling. The FDA imposes stringent restrictions on manufacturers’ communications regarding off-label use and if we, or our future collaborators, do not market any of our drug candidates for which we, or they, receive marketing approval for only their approved indications, we, or they, may be subject to warnings or enforcement action for off-label marketing. Violation of the FDCA and other statutes, including the False Claims Act, relating to the promotion and advertising of prescription drugs may lead to investigations or allegations of violations of federal and state health care fraud and abuse laws and state consumer protection laws.

In addition, later discovery of previously unknown adverse events or other problems with our drugs or their manufacturers or manufacturing processes, or failure to comply with regulatory requirements, may yield various results, including:

• litigation involving patients taking our drug;

• restrictions on such drugs, manufacturers or manufacturing processes;

• restrictions on the labeling or marketing of a drug;

• restrictions on drug distribution or use;

• requirements to conduct post-marketing studies or clinical trials;

• warning letters or untitled letters;

• withdrawal of the drugs from the market;

• refusal to approve pending applications or supplements to approved applications that we submit;

• recall of drugs;

• fines, restitution or disgorgement of profits or revenues;

• suspension or withdrawal of marketing approvals;

• damage to relationships with any potential collaborators;

• unfavorable press coverage and damage to our reputation;

• refusal to permit the import or export of drugs;

• drug seizure; or

• injunctions or the imposition of civil or criminal penalties.

Existing laws and future legislation may increase the difficulty and cost for us and our future collaborators to obtain marketing approval of and commercialize our drug candidates and affect the prices we, or they, may obtain.

In the United States and some foreign jurisdictions, there have been a number of legislative and regulatory changes and proposed changes regarding the healthcare system that could prevent or delay marketing approval of our drug candidates, restrict or regulate post-approval activities and affect our ability, or the ability of our future collaborators, to profitably sell any drugs for which we, or they, obtain marketing approval. We expect that current laws, as well as other healthcare reform measures that be adopted in the future, may result in more rigorous coverage criteria and in additional downward pressure on the price that we, or our future collaborators, may receive for any approved drugs.

In the United States, the Medicare Prescription Drug, Improvement, and Modernization Act of 2003, or the MMA, changed the way Medicare covers and pays for pharmaceutical products and could decrease the coverage and price that we, or our future collaborators, may receive for any approved drugs. While the MMA only addresses drug benefits for Medicare beneficiaries, private payors often follow Medicare coverage policy and payment limitations in setting their own reimbursement rates. Therefore, any reduction in reimbursement that results from the MMA may result in a similar reduction in payments from private payors.

In addition, the Patient Protection and Affordable Care Act, as amended by the Health Care and Education Affordability Reconciliation Act, or collectively the PPACA, includes the following provisions of potential importance to our drug candidates:

• an annual, non-deductible fee on any entity that manufactures or imports specified branded prescription drugs and biologic agents;

• an increase in the statutory minimum rebates a manufacturer must pay under the Medicaid Drug Rebate Program;

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• expansion of healthcare fraud and abuse laws, including the False Claims Act and the Anti-Kickback Statute, new government investigative powers and enhanced penalties for non-compliance;

• a new Medicare Part D coverage gap discount program, in which manufacturers must agree to offer 50% point-of-sale discounts off negotiated prices;

• extension of manufacturers’ Medicaid rebate liability;

• expansion of eligibility criteria for Medicaid programs;

• expansion of the entities eligible for discounts under the Public Health Service pharmaceutical pricing program;

• new requirements to report financial arrangements with physicians and teaching hospitals;

• a new requirement to annually report drug samples that manufacturers and distributors provide to physicians; and

• a new Patient-Centered Outcomes Research Institute to oversee, identify priorities in, and conduct comparative clinical effectiveness research, along with funding for such research.

Further, other legislative changes have been proposed and adopted since the PPACA was enacted. These new laws may result in additional reductions in Medicare and other healthcare funding and otherwise affect the prices we may obtain for any of our drug candidates for which marketing approval is obtained.

We expect that the PPACA, as well as other healthcare reform measures that may be adopted in the future, may result in more rigorous coverage criteria and in additional downward pressure on the price that we receive for any approved drug. Any reduction in reimbursement from Medicare or other government programs may result in a similar reduction in payments from private payors. The implementation of cost containment measures or other healthcare reforms may prevent us from being able to generate revenue from sales of drugs, attain profitability, or commercialize our drug candidates.

Legislative and regulatory proposals have been made to expand post-approval requirements and restrict sales and promotional activities for pharmaceutical products. We cannot be sure whether additional legislative changes will be enacted, or whether FDA regulations, guidance or interpretations will be changed, or what the impact of such changes on the marketing approvals of our drug candidates, if any, may be. In addition, increased scrutiny by the United States Congress of the FDA’s approval process may significantly delay or prevent marketing approval, as well as subject us and our future collaborators to more stringent drug labeling and post-marketing testing and other requirements.

Our relationships with healthcare providers and physicians and third-party payors will be subject to applicable anti-kickback, fraud and abuse and other healthcare laws and regulations, which could expose us to criminal sanctions, civil penalties, contractual damages, reputational harm and diminished profits and future earnings.

Healthcare providers, physicians and third party payors will play a primary role in the recommendation and prescription of any drugs for which we obtain marketing approval. Our future arrangements with third party payors, healthcare providers and physicians may expose us to broadly applicable fraud and abuse and other healthcare laws and regulations that may constrain the business or financial arrangements and relationships through which we market, sell and distribute any drugs for which we obtain marketing approval. These include the following:

• Anti-Kickback Statute—the federal healthcare anti-kickback statute prohibits, among other things, persons from knowingly and willfully soliciting, offering, receiving or providing remuneration, directly or indirectly, in cash or in kind, to induce or reward, or in return for, either the referral of an individual for, or the purchase, order or recommendation or arranging of, any good or service, for which payment may be made under a federal healthcare program such as Medicare and Medicaid;

• False Claims Act—the federal False Claims Act imposes criminal and civil penalties, including through civil whistleblower or qui tam actions, against individuals or entities for, among other things, knowingly presenting, or causing to be presented false or fraudulent claims for payment by a federal healthcare program or making a false statement or record material to payment of a false claim or avoiding, decreasing or concealing an obligation to pay money to the federal government, with potential liability including mandatory treble damages and significant per-claim penalties, currently set at $5,500 to $11,000 per false claim;

• HIPAA—the federal Health Insurance Portability and Accountability Act of 1996, or HIPAA, imposes criminal and civil liability for executing a scheme to defraud any healthcare benefit program or making false statements relating to healthcare matters, and, as amended by the Health Information Technology for Economic and Clinical Health Act and its implementing regulations, also imposes obligations, including mandatory contractual terms and technical safeguards, with respect to maintaining the privacy, security and transmission of individually identifiable health information;

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• Transparency Requirements—federal laws require applicable manufacturers of covered drugs to report payments and other transfers of value to physicians and teaching hospitals; and

• Analogous State and Foreign Laws—analogous state and foreign fraud and abuse laws and regulations, such as state anti-kickback and false claims laws, can apply to sales or marketing arrangements and claims involving healthcare items or services and are generally broad and are enforced by many different federal and state agencies as well as through private actions.

Some state laws require pharmaceutical companies to comply with the pharmaceutical industry’s voluntary compliance guidelines and the relevant compliance guidance promulgated by the federal government and require drug manufacturers to report information related to payments and other transfers of value to physicians and other healthcare providers or marketing expenditures. State and foreign laws also govern the privacy and security of health information in some circumstances, many of which differ from each other in significant ways and often are not pre-empted by HIPAA, thus complicating compliance efforts.

Efforts to ensure that our business arrangements with third parties will comply with applicable healthcare laws and regulations will involve substantial costs. It is possible that governmental authorities will conclude that our business practices may not comply with current or future statutes, regulations or case law involving applicable fraud and abuse or other healthcare laws and regulations. If our operations are found to be in violation of any of these laws or any other governmental regulations that may apply to us, we may be subject to significant civil, criminal and administrative penalties, damages, fines, imprisonment, exclusion of drugs from government funded healthcare programs, such as Medicare and Medicaid, and the curtailment or restructuring of our operations. If any of the physicians or other healthcare providers or entities with whom we expect to do business is found to be not in compliance with applicable laws, they may be subject to criminal, civil or administrative sanctions, including exclusions from government funded healthcare programs.

Our employees may engage in misconduct or other improper activities, including non-compliance with regulatory standards and requirements, which could cause significant liability for us and harm our reputation.

We are exposed to the risk of employee fraud or other misconduct, including intentional failures to comply with FDA regulations or similar regulations of comparable foreign regulatory authorities, provide accurate information to the FDA or comparable foreign regulatory authorities, comply with manufacturing standards we have established, comply with federal and state healthcare fraud and abuse laws and regulations and similar laws and regulations established and enforced by comparable foreign regulatory authorities, report financial information or data accurately or disclose unauthorized activities to us. Employee misconduct could also involve the improper use of information obtained in the course of clinical trials, which could result in regulatory sanctions and serious harm to our reputation. It is not always possible to identify and deter employee misconduct, and the precautions we take to detect and prevent this activity may not be effective in controlling unknown or unmanaged risks or losses or in protecting us from governmental investigations or other actions or lawsuits stemming from a failure to be in compliance with such laws, standards or regulations. If any such actions are instituted against us, and we are not successful in defending ourselves or asserting our rights, those actions could have a significant impact on our business and results of operations, including the imposition of significant fines or other sanctions.

If we fail to comply with environmental, health and safety laws and regulations, we could become subject to fines or penalties or incur costs that could have a material adverse effect on our business.

We are subject to numerous environmental, health and safety laws and regulations, including those governing laboratory procedures and the handling, use, storage, treatment and disposal of hazardous materials and wastes. Our operations involve the use of hazardous and flammable materials, including chemicals and biological and radioactive materials. Our operations also produce hazardous waste products. We generally contract with third parties for the disposal of these materials and wastes. We cannot eliminate the risk of contamination or injury from these materials. In the event of contamination or injury resulting from our use of hazardous materials, we could be held liable for any resulting damages, and any liability could exceed our resources. We also could incur significant costs associated with civil or criminal fines and penalties.

Although we maintain workers’ compensation insurance to cover us for costs and expenses we may incur due to injuries to our employees resulting from the use of hazardous materials, this insurance may not provide adequate coverage against potential liabilities. We do not maintain insurance for environmental liability or toxic tort claims that may be asserted against us in connection with our storage or disposal of biological, hazardous or radioactive materials.

In addition, we may incur substantial costs in order to comply with current or future environmental, health and safety laws and regulations. These current or future laws and regulations may impair our research, development or commercialization efforts. Failure to comply with these laws and regulations also may result in substantial fines, penalties or other sanctions.

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Laws and regulations governing any international operations we may have in the future may preclude us from developing, manufacturing and selling certain drug candidates outside of the United States and require us to develop and implement costly compliance programs.

We are subject to numerous laws and regulations in each jurisdiction outside the United States in which we operate. The creation, implementation and maintenance of international business practices compliance programs is costly and such programs are difficult to enforce, particularly where reliance on third parties is required.

The FCPA prohibits any U.S. individual or business from paying, offering, authorizing payment or offering of anything of value, directly or indirectly, to any foreign official, political party or candidate for the purpose of influencing any act or decision of the foreign entity in order to assist the individual or business in obtaining or retaining business. The FCPA also obligates companies whose securities are listed in the United States to comply with certain accounting provisions requiring the company to maintain books and records that accurately and fairly reflect all transactions of the corporation, including international subsidiaries, and to devise and maintain an adequate system of internal accounting controls for international operations. The anti-bribery provisions of the FCPA are enforced primarily by the DOJ. The Securities and Exchange Commission, or SEC, is involved with enforcement of the books and records provisions of the FCPA.

Compliance with the FCPA is expensive and difficult, particularly in countries in which corruption is a recognized problem. In addition, the FCPA presents particular challenges in the pharmaceutical industry, because, in many countries, hospitals are operated by the government, and doctors and other hospital employees are considered foreign officials. Certain payments to hospitals in connection with clinical trials and other work have been deemed to be improper payments to government officials and have led to FCPA enforcement actions.

Various laws, regulations and executive orders also restrict the use and dissemination outside of the United States, or the sharing with certain non-U.S. nationals, of information classified for national security purposes, as well as certain products and technical data relating to those products. Our expansion outside of the United States, has required, and will continue to require, us to dedicate additional resources to comply with these laws, and these laws may preclude us from developing, manufacturing, or selling certain drugs and drug candidates outside of the United States, which could limit our growth potential and increase our development costs. The failure to comply with laws governing international business practices may result in substantial penalties, including suspension or debarment from government contracting. Violation of the FCPA can result in significant civil and criminal penalties. Indictment alone under the FCPA can lead to suspension of the right to do business with the U.S. government until the pending claims are resolved. Conviction of a violation of the FCPA can result in long-term disqualification as a government contractor. The termination of a government contract or relationship as a result of our failure to satisfy any of our obligations under laws governing international business practices would have a negative impact on our operations and harm our reputation and ability to procure government contracts. The SEC also may suspend or bar issuers from trading securities on U.S. exchanges for violations of the FCPA’s accounting provisions.

Governments outside of the United States tend to impose strict price controls, which may adversely affect our revenues from the sales of drugs, if any.

In some countries, particularly the countries of the European Union, the pricing of prescription pharmaceuticals is subject to governmental control. In these countries, pricing negotiations with governmental authorities can take considerable time after the receipt of marketing approval for a drug. To obtain reimbursement or pricing approval in some countries, we, or our future collaborators, may be required to conduct a clinical trial that compares the cost-effectiveness of our drug to other available therapies. If reimbursement of our drugs is unavailable or limited in scope or amount, or if pricing is set at unsatisfactory levels, our business could be materially harmed.

Risks Related to Employee Matters and Managing Growth

Our future success depends on our ability to retain our Chief Executive Officer, our President and Chief Scientific Officer and other key executives and to attract, retain and motivate qualified personnel.

We are highly dependent on Michael Kauffman, M.D., Ph.D., our Chief Executive Officer, and Sharon Shacham, Ph.D., M.B.A., our President and Chief Scientific Officer, as well as the other principal members of our management and scientific teams. Although we have entered into formal employment agreements with Drs. Kauffman and Shacham, these agreements do not prevent them from terminating their employment with us at any time. We do not maintain “key person” insurance for any of our executives or other employees. The loss of the services of any of these persons could impede the achievement of our research, development and commercialization objectives.

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Recruiting and retaining qualified scientific, clinical, manufacturing and sales and marketing personnel will also be critical to our success. We may not be able to attract and retain these personnel on acceptable terms given the competition among numerous pharmaceutical and biotechnology companies for similar personnel. We also experience competition for the hiring of scientific and clinical personnel from universities and research institutions. In addition, we rely on consultants and advisors, including scientific and clinical advisors, to assist us in formulating our research and development and commercialization strategy. Our consultants and advisors may be employed by employers other than us and may have commitments under consulting or advisory contracts with other entities that may limit their availability to us.

Drs. Kauffman and Shacham are married to each other. The separation or divorce of the couple in the future could adversely affect our business.

Dr. Kauffman, our Chief Executive Officer and member of our board of directors, and Dr. Shacham, our President and Chief Scientific Officer, are married to each other. They are two of our executive officers and are a vital part of our operations. If they were to become separated or divorced or could otherwise not amicably work with each other, one of them may decide to cease his or her employment with us or it could negatively impact our working environment. Alternatively, their work performance may not be satisfactory if they become preoccupied with issues relating to their personal situation. In these cases, our business could be materially harmed.

We expect to expand our development, regulatory and future sales and marketing capabilities, and as a result, we may encounter difficulties in managing our growth, which could disrupt our operations.

We expect to experience significant growth in the number of our employees and the scope of our operations, particularly in the areas of drug development, regulatory affairs and, potentially, sales and marketing. To manage our anticipated future growth, we must continue to implement and improve our managerial, operational and financial systems, expand our facilities and continue to recruit and train additional qualified personnel. Due to our limited financial resources and the limited experience of our management team in managing a company with such anticipated growth, we may not be able to effectively manage the expansion of our operations or recruit and train additional qualified personnel. The physical expansion of our operations may lead to significant costs and may divert our management and business development resources. Any inability to manage growth could delay the execution of our business plans or disrupt our operations.

Our business and operations may be materially adversely affected in the event of computer system failures or security breaches.

Despite the implementation of security measures, our internal computer systems, and those of our contract research organizations and other third parties on which we rely, are vulnerable to damage from computer viruses, unauthorized access, cyber attacks, natural disasters, fire, terrorism, war and telecommunication and electrical failures. If such an event were to occur and cause interruptions in our operations, it could result in a material disruption of our drug development programs. For example, the loss of clinical trial data from ongoing or planned clinical trials could result in delays in our regulatory approval efforts and significantly increase our costs to recover or reproduce the data. To the extent that any disruption or security breach results in a loss of or damage to our data or applications, or inappropriate disclosure of confidential or proprietary information, we could incur liability and the further development of our drug candidates could be delayed. We may also be vulnerable to cyber attacks by hackers, or other malfeasance. This type of breach of our cybersecurity may compromise our confidential information and/or our financial information and adversely affect our business or result in legal proceedings.

Risks Related to Our Common Stock

Our executive officers, directors and principal stockholders maintain the ability to control all matters submitted to stockholders for approval.

As of June 30, 2016, our executive officers, directors and a small number of stockholders own more than a majority of our outstanding common stock. As a result, if these stockholders were to choose to act together, they would be able to control all matters submitted to our stockholders for approval, as well as our management and affairs. For example, these persons, if they choose to act together, would control the election of directors and approval of any merger, consolidation or sale of all or substantially all of our assets. This concentration of voting power could delay or prevent an acquisition of our company on terms that other stockholders may desire.

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Provisions in our corporate charter documents and under Delaware law could make an acquisition of us, which may be beneficial to our stockholders, more difficult and may prevent attempts by our stockholders to replace or remove our current management.

Provisions in our corporate charter and our bylaws may discourage, delay or prevent a merger, acquisition or other change in control of us that stockholders may consider favorable, including transactions in which stockholders might otherwise receive a premium for their shares. These provisions could also limit the price that investors might be willing to pay in the future for shares of our common stock, thereby depressing the market price of our common stock. In addition, because our board of directors is responsible for appointing the members of our management team, these provisions may frustrate or prevent any attempts by our stockholders to replace or remove our current management by making it more difficult for stockholders to replace members of our board of directors. Among other things, these provisions:

• establish a classified board of directors such that not all members of the board are elected at one time;

• allow the authorized number of our directors to be changed only by resolution of our board of directors;

• limit the manner in which stockholders can remove directors from the board;

• establish advance notice requirements for stockholder proposals that can be acted on at stockholder meetings and nominations to our board of directors;

• require that stockholder actions must be effected at a duly called stockholder meeting and prohibit actions by our stockholders by written consent;

• limit who may call stockholder meetings;

• authorize our board of directors to issue preferred stock without stockholder approval, which could be used to institute a “poison pill” that would work to dilute the stock ownership of a potential hostile acquirer, effectively preventing acquisitions that have not been approved by our board of directors; and

• require the approval of the holders of at least 75% of the votes that all our stockholders would be entitled to cast to amend or repeal certain provisions of our charter or bylaws.

Moreover, because we are incorporated in Delaware, we are governed by the provisions of Section 203 of the Delaware General Corporation Law, which prohibits a person who owns in excess of 15% of our outstanding voting stock from merging or combining with us for a period of three years after the date of the transaction in which the person acquired in excess of 15% of our outstanding voting stock, unless the merger or combination is approved in a prescribed manner.

An active trading market for our common stock may not be sustained.

Although our common stock is listed on The NASDAQ Global Select Market, an active trading market for our shares may not be sustained. If an active market for our common stock does not continue, it may be difficult for you to sell shares of our common stock without depressing the market price for the shares, or at all. An inactive trading market for our common stock may also impair our ability to raise capital to continue to fund our operations by selling shares and may impair our ability to acquire other companies or technologies by using our shares as consideration.

If securities analysts do not continue to publish research or reports about our business or if they publish negative evaluations of our stock, the price of our stock could decline.

The trading market for our common stock relies in part on the research and reports that industry or financial analysts publish about us or our business. There can be no assurance that analysts will provide favorable coverage or continue to cover us. If one or more of the analysts covering our business downgrade their evaluations of our stock, the price of our stock could decline. If one or more of these analysts cease to cover our stock, we could lose visibility in the market for our stock, which in turn could cause our stock price to decline.

The price of our common stock has been and may be volatile in the future and fluctuate substantially.

Our stock price has been and is likely to be volatile and may fluctuate substantially. For example, since January 1, 2015, our common stock has traded at prices per share as high as $38.47 and as low as $4.83. The stock market in general and the market for pharmaceutical and biotechnology companies in particular have experienced extreme volatility that has often been unrelated to the operating performance of particular companies. The market price for our common stock may be influenced by many factors, including:

• the success of competitive drugs or technologies;

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• results of clinical trials of our drug candidates or those of our competitors;

• regulatory or legal developments in the United States and other countries;

• developments or disputes concerning patent applications, issued patents or other proprietary rights;

• the recruitment or departure of key personnel;

• the level of expenses related to any of our drug candidates or clinical development programs;

• the results of our efforts to discover, develop, acquire or in-license additional drug candidates or drugs;

• actual or anticipated changes in estimates as to financial results, development timelines or recommendations by securities analysts;

• variations in our financial results or those of companies that are perceived to be similar to us;

• changes in the structure of healthcare payment systems;

• market conditions in the pharmaceutical and biotechnology sectors;

• general economic, industry and market conditions; and

• the other factors described in this “Risk Factors” section.

We could be subject to securities class action litigation.

In the past, securities class action litigation has often been brought against a company following a decline in the market price of its securities. This risk is especially relevant for us because pharmaceutical companies have experienced significant stock price volatility in recent years. If we face such litigation, it could result in substantial costs and a diversion of management’s attention and our resources, which could harm our business.

We have broad discretion in the use of our cash and cash equivalents and may not use them effectively.

Our management has broad discretion to use our cash and cash equivalents to fund our operations and could spend these funds in ways that do not improve our results of operations or enhance the value of our common stock. The failure by our management to apply these funds effectively could result in financial losses that could have a material adverse effect on our business, cause the price of our common stock to decline and delay the development of our drug candidates. Pending their use to fund our operations, we may invest our cash and cash equivalents in a manner that does not produce income or that loses value.

We are an “emerging growth company,” and the reduced disclosure requirements applicable to emerging growth companies may make our common stock less attractive to investors.

We are an “emerging growth company,” as defined in the Jumpstart Our Business Startups Act of 2012, or the JOBS Act, and may remain an emerging growth company through 2018. For so long as we remain an emerging growth company, we are permitted and intend to rely on exemptions from certain disclosure requirements that are applicable to other public companies that are not emerging growth companies. These exemptions include not being required to comply with the auditor attestation requirements of Section 404 of the Sarbanes-Oxley Act of 2002, not being required to comply with any requirement that may be adopted by the Public Company Accounting Oversight Board regarding mandatory audit firm rotation or a supplement to the auditor’s report providing additional information about the audit and the financial statements, reduced disclosure obligations regarding executive compensation and exemptions from the requirements of holding a nonbinding advisory vote on executive compensation and shareholder approval of any golden parachute payments not previously approved. We cannot predict whether investors will find our common stock less attractive if we rely on these exemptions. If some investors find our common stock less attractive as a result, there may be a less active trading market for our common stock and our stock price may be more volatile.

In addition, the JOBS Act provides that an emerging growth company can take advantage of an extended transition period for complying with new or revised accounting standards. This allows an emerging growth company to delay the adoption of certain accounting standards until those standards would otherwise apply to private companies. We have irrevocably elected not to avail ourselves of this exemption from new or revised accounting standards and, therefore, we will be subject to the same new or revised accounting standards as other public companies that are not emerging growth companies.

47

We will continue to incur increased costs as a result of operating as a public company, and our management will need to continue to devote substantial time to compliance initiatives and corporate governance practices.

As a public company, and particularly after we are no longer an “emerging growth company,” we will incur significant legal, accounting and other expenses. In addition, the Sarbanes-Oxley Act of 2002 and rules subsequently implemented by the SEC and NASDAQ have imposed various requirements on public companies, including establishment and maintenance of effective disclosure and financial controls and corporate governance practices. Our management and other personnel will need to continue to devote a substantial amount of time to these compliance initiatives. Moreover, these rules and regulations will increase our legal and financial compliance costs and will make some activities more time-consuming and costly.

We cannot predict with certainty the amount of additional costs we may incur to continue to operate as a public company, nor can we predict the timing of such costs. In addition, the rules and regulations applicable to public companies are often subject to varying interpretations, in many cases due to their lack of specificity, and, as a result, their application in practice may evolve over time as new guidance is provided by regulatory and governing bodies which could result in continuing uncertainty regarding compliance matters and higher costs necessitated by ongoing revisions to disclosure and governance practices.

Pursuant to Section 404 of the Sarbanes-Oxley Act of 2002, or Section 404, we are required to furnish a report by our management on our internal control over financial reporting. However, while we remain an emerging growth company, we are not required to include an attestation report on internal control over financial reporting issued by our independent registered public accounting firm. To achieve compliance with Section 404 within the prescribed period, we are engaged in a process to document and evaluate our internal control over financial reporting, which is both costly and challenging. In this regard, we will need to continue to dedicate internal resources, potentially engage outside consultants and adopt a detailed work plan to assess and document the adequacy of internal control over financial reporting, continue steps to improve control processes as appropriate, validate through testing that controls are functioning as documented and implement a continuous reporting and improvement process for internal control over financial reporting. There is a risk that neither we nor our independent registered public accounting firm will be able to conclude within the prescribed timeframe that our internal control over financial reporting is effective as required by Section 404. This could result in an adverse reaction in the financial markets due to a loss of confidence in the reliability of our financial statements. In addition, if we identify one or more material weaknesses, it could result in an adverse reaction in the financial markets due to a loss of confidence in the reliability of our financial statements.

Because we do not anticipate paying any cash dividends on our capital stock in the foreseeable future, capital appreciation, if any, of our common stock will be the sole source of gain for our stockholders.

We have never declared or paid cash dividends on our capital stock. We currently intend to retain all of our future earnings, if any, to finance the growth and development of our business. In addition, the terms of any future debt agreements may preclude us from paying dividends. As a result, capital appreciation, if any, of our common stock will be the sole source of gain for our stockholders for the foreseeable future.

A significant portion of our total outstanding shares are restricted from immediate resale but may be sold into the market in the near future, which could cause the market price of our common stock to drop significantly, even if our business is doing well.

Sales of a substantial number of shares of our common stock in the public market could occur at any time. These sales, or the perception in the market that the holders of a large number of shares intend to sell shares, could reduce the market price of our common stock. We had 35,964,260 shares outstanding as of June 30, 2016. Of such shares, at least 11.6 million shares are eligible for sale in the public market under Rule 144 of the Securities Act of 1933, as amended, or the Securities Act, subject to the volume limitations and other conditions of Rule 144. The holders of these shares may at any time decide to sell their shares in the public market.

Moreover, holders of an aggregate of approximately 11.7 million shares of our common stock as of June 30, 2016 have rights, subject to some conditions, to require us to file registration statements covering their shares or to include their shares in registration statements that we may file for ourselves or other stockholders. We have also registered all shares of common stock that we may issue under our equity compensation plans. As a result, these shares can be freely sold in the public market upon issuance, subject to volume limitations applicable to affiliates, to the extent applicable.

48

Our ability to use our net operating loss carryforwards and tax credit carryforwards to offset future taxable income may be subject to certain limitations.

Under the provisions of the Internal Revenue Code of 1986, as amended, or the Code, our net operating loss and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service (and state tax authorities under relevant state tax rules). The use of net operating loss and tax credit carryforwards may become subject to an annual limitation under Sections 382 and 383 of the Code, respectively, and similar state provisions in the event of certain cumulative changes in the ownership interest of significant shareholders in excess of 50 percent over a three-year period. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the value of a company immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years. Our company has completed several financings since its inception that may have resulted in ownership changes under Sections 382 and 383 of the Code. In addition, future changes in our stock ownership, some of which are outside of our control, could result in ownership changes in the future. For these reasons, we may not be able to use some or all of our net operating loss and tax credit carryforwards, even if we attain profitability prior to the expiration of our net operating loss and tax credit carryforwards.

Item 6. Exhibits.

The exhibits filed as part of this Quarterly Report on Form 10-Q are set forth on the Exhibit Index, which Exhibit Index is incorporated herein by reference.

49

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

	KARYOPHARM THERAPEUTICS INC.
Date: August 4, 2016	By:	/s/ MICHAEL KAUFFMAN
		Michael Kauffman, M.D., Ph.D.
		Chief Executive Officer
		(Principal executive officer)
Date: August 4, 2016	By:	/s/ JUSTIN A. RENZ
		Justin A. Renz
		Executive Vice President and Chief Financial Officer
		(Principal financial and accounting officer)

50

EXHIBIT INDEX

Exhibit		Form	Incorporated by Reference			Filed
Number	Description of Exhibit		File Number	Date of Filing	Exhibit Number	Herewith
31.1	Certification of principal executive officer pursuant to Rule 13a-14(a)/15d-14(a) of the Securities Exchange Act of 1934, as amended.					X
31.2	Certification of principal financial officer pursuant to Rule 13a-14(a)/15d-14(a) of the Securities Exchange Act of 1934, as amended.					X
32.1	Certification of principal executive officer pursuant to 18 U.S.C. §1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.					X
32.2	Certification of principal financial officer pursuant to 18 U.S.C. §1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.					X
101.INS	Instance Document					X
101.SCH	Scheme Document					X
101.CAL	Calculation Linkbase Document					X
101.DEF	Definition Linkbase Document					X
101.LAB	Labels Linkbase Document					X
101.PRE	Presentation Linkbase Document					X

EX-31.1

Exhibit 31.1

CERTIFICATIONS

I, Michael Kauffman, M.D., Ph.D., certify that:

1. I have reviewed this Quarterly Report on Form 10-Q of Karyopharm Therapeutics Inc.;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and have:

a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c) Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d) Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

/s/ MICHAEL KAUFFMAN

Michael Kauffman, M.D., Ph.D.

Chief Executive Officer

(Principal executive officer)

Date: August 4, 2016

EX-31.2

Exhibit 31.2

CERTIFICATIONS

I, Justin A. Renz, certify that:

1. I have reviewed this Quarterly Report on Form 10-Q of Karyopharm Therapeutics Inc.;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and have:

a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c) Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d) Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

/s/ JUSTIN A. RENZ

Justin A. Renz

Executive Vice President and Chief Financial Officer

(Principal financial and accounting officer)

Date: August 4, 2016

EX-32.1

Exhibit 32.1

CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report on Form 10-Q of Karyopharm Therapeutics Inc. (the “Company”) for the period ended June 30, 2016, as filed with the Securities and Exchange Commission on the date hereof (the “Report”), the undersigned, Michael Kauffman, M.D., Ph.D., Chief Executive Officer of the Company, hereby certifies, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that to his knowledge:

(1) the Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2) the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

/s/ MICHAEL KAUFFMAN

Michael Kauffman, M.D., Ph.D.

Chief Executive Officer

(Principal executive officer)

Date: August 4, 2016

EX-32.2

Exhibit 32.2

CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report on Form 10-Q of Karyopharm Therapeutics Inc. (the “Company”) for the period ended June 30, 2016, as filed with the Securities and Exchange Commission on the date hereof (the “Report”), the undersigned, Justin A. Renz, Executive Vice President and Chief Financial Officer of the Company, hereby certifies, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that to his knowledge:

(1) the Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2) the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

/s/ JUSTIN A. RENZ

Justin A. Renz

Executive Vice President and Chief Financial Officer

(Principal financial and accounting officer)

Date: August 4, 2016

XML

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2016	Jul. 31, 2016
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2016
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	Q2
Trading Symbol	KPTI
Entity Registrant Name	KARYOPHARM THERAPEUTICS INC.
Entity Central Index Key	0001503802
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		35,989,260

XML

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 37,717	$ 58,358
Short-term investments	85,019	117,275
Prepaid expenses and other current assets	1,464	1,967
Total current assets	124,200	177,600
Property and equipment, net	3,170	3,483
Long-term investments	42,933	33,878
Restricted cash	483	482
Other assets	111
Total assets	170,897	215,443
Current liabilities:
Accounts payable	4,063	3,808
Accrued expenses	11,112	11,023
Deferred rent	269	206
Other current liabilities	79	95
Total current liabilities	15,523	15,132
Deferred rent, net of current portion	1,808	1,946
Total liabilities	17,331	17,078
Stockholders' equity:
Preferred stock, $0.0001 par value; 5,000,000 shares authorized; none issued and outstanding
Common stock, $0.0001 par value; 100,000,000 shares authorized; 35,989,260 and 35,864,765 shares issued and outstanding at June 30, 2016 and December 31, 2015, respectively	4	4
Additional paid-in capital	467,168	455,170
Accumulated other comprehensive income (loss)	138	(282)
Accumulated deficit	(313,744)	(256,527)
Total stockholders' equity	153,566	198,365
Total liabilities and stockholders' equity	$ 170,897	$ 215,443

XML

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	35,989,260	35,864,765
Common stock, shares outstanding	35,989,260	35,864,765

XML

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Statement [Abstract]
Contract and grant revenue	$ 59	$ 150	$ 59	$ 150
Operating expenses:
Research and development	24,579	27,006	46,374	47,757
General and administrative	5,956	6,157	11,510	11,556
Total operating expenses	30,535	33,163	57,884	59,313
Loss from operations	(30,476)	(33,013)	(57,825)	(59,163)
Other income:
Interest income	329	267	615	408
Other income (expense)	(11)	51	(7)	(7)
Total other income, net	318	318	608	401
Net loss	$ (30,158)	$ (32,695)	$ (57,217)	$ (58,762)
Net loss per share-basic and diluted	$ (0.84)	$ (0.92)	$ (1.59)	$ (1.65)
Weighted-average number of common shares outstanding used in net loss per share-basic and diluted	35,956,470	35,697,012	35,917,486	35,508,146

XML

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Net loss	$ (30,158)	$ (32,695)	$ (57,217)	$ (58,762)
Comprehensive income (loss)
Unrealized gain (loss) on investments	64	(94)	407	(42)
Foreign currency translation adjustments	(20)	(68)	13	(73)
Comprehensive loss	$ (30,114)	$ (32,857)	$ (56,797)	$ (58,877)

XML

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Operating activities
Net loss	$ (57,217)	$ (58,762)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	358	292
Net amortization of premiums and discounts on investments	595	816
Stock-based compensation expense	11,563	8,231
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	503	(2,038)
Other assets	(89)	774
Accounts payable	233	(1,782)
Accrued expenses and other liabilities	70	3,446
Deferred rent	(75)	699
Net cash used in operating activities	(44,059)	(48,324)
Investing activities
Purchases of property and equipment	(45)	(774)
Proceeds from maturities of investments	110,046	41,069
Purchases of investments	(87,033)	(209,517)
Net cash provided by (used in) investing activities	22,968	(169,222)
Financing activities
Proceeds from the issuance of common stock, net of issuance costs		90,830
Proceeds from the exercise of stock options and shares issued under employee stock purchase plan	436	347
Net cash provided by financing activities	436	91,177
Effect of exchange rate on cash	14	(9)
Net decrease in cash and cash equivalents	(20,641)	(126,378)
Cash and cash equivalents at beginning of period	58,358	150,609
Cash and cash equivalents at end of period	37,717	24,231
Supplemental disclosure of non-cash financing activity
Property and equipment purchases included in accounts payable and accrued expenses		52
Vesting of restricted common stock		$ 84
Deferred financing costs included in accounts payable	$ 22

XML

Summary of Significant Accounting Policies

6 Months Ended

Jun. 30, 2016

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

1. Summary of Significant Accounting Policies

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements of Karyopharm Therapeutics Inc. (the “Company”) have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial reporting and as required by Regulation S-X, Rule 10-01. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments (including those which are normal and recurring) considered necessary for a fair presentation of the interim financial information have been included. When preparing financial statements in conformity with GAAP, the Company must make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, expenses and related disclosures at the date of the financial statements. Actual results could differ from those estimates. Additionally, operating results for the three and six months ended June 30, 2016 are not necessarily indicative of the results that may be expected for any other interim period or for the fiscal year ending December 31, 2016. For further information, refer to the financial statements and footnotes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2015 as filed with the Securities and Exchange Commission (“SEC”) on March 15, 2016.

Basis of Consolidation

The condensed consolidated financial statements at June 30, 2016 include the accounts of Karyopharm Therapeutics Inc. (a Delaware corporation), the accounts of Karyopharm Securities Corp. (a wholly-owned Massachusetts corporation of the Company incorporated in December 2013), the accounts of Karyopharm Europe GmbH (a wholly-owned German Limited Liability Company formed in August 2014), and the accounts of Karyopharm Therapeutics (Bermuda) Ltd. (a wholly-owned Bermuda subsidiary of the Company formed in March 2015). All intercompany balances and transactions have been eliminated in consolidation.

XML

Recently Issued Accounting Pronouncements

6 Months Ended

Jun. 30, 2016

Accounting Changes and Error Corrections [Abstract]

Recently Issued Accounting Pronouncements

2. Recently Issued Accounting Pronouncements

In August 2014, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) No. 2014-15, Presentation of Financial Statements—Going Concern (Subtopic 205-40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern. ASU No. 2014-15 is intended to define management’s responsibility to evaluate whether there is substantial doubt about an organization’s ability to continue as a going concern and to provide related footnote disclosures. Substantial doubt about an entity’s ability to continue as a going concern exists when relevant conditions and events, considered in the aggregate, indicate that it is probable that the entity will be unable to meet its obligations as they become due within one year after the date that the financial statements are issued (or available to be issued). ASU No. 2014-15 provides guidance to an organization’s management, with principles and definitions that are intended to reduce diversity in the timing and content of disclosures that are commonly provided by organizations in the financial statement footnotes. ASU No. 2014-15 is effective for annual reporting periods ending after December 15, 2016, and for annual and interim periods thereafter. Early adoption is permitted. The Company does not expect the adoption of ASU No. 2014-15 to have a material impact on its consolidated financial statements, but it may impact the Company’s disclosures.

In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers, which defers the effective date of ASU 2014-09 for all entities by one year. ASU 2014-09 is now effective for public companies for annual reporting periods beginning after December 15, 2017, including interim periods within those reporting periods. Early adoption is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. ASU 2014-09 outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most of the current revenue recognition guidance, including industry-specific guidance. In addition, ASU 2014-09 provides guidance on accounting for certain revenue-related costs including, but not limited to, when to capitalize costs associated with obtaining and fulfilling a contract. ASU 2014-09 provides companies with two implementation methods. Companies can choose to apply the standard retrospectively to each prior reporting period presented (full retrospective application) or retrospectively with the cumulative effect of initially applying the standard as an adjustment to the opening balance of retained earnings of the annual reporting period that includes the date of initial application (modified retrospective application). The Company continues to evaluate the expected impact of this new guidance and available adoption methods.

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). The new standard requires that all lessees recognize the assets and liabilities that arise from leases on the balance sheet and disclose qualitative and quantitative information about its leasing arrangements. The new standard will be effective for the Company on January 1, 2019. The Company is currently evaluating the potential impact that this standard may have on its consolidated financial statements.

In March 2016, the FASB issued ASU No. 2016-09, Compensation – Stock Compensation (Topic 718). The new standard identifies areas for simplification involving several aspects of accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, an option to recognize gross stock compensation expense with actual forfeitures recognized as they occur, as well as certain classifications on the statement of cash flows. The standard is effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods. Early adoption is permitted. An entity that elects early adoption must adopt all of the provisions of the standard in the same period. The Company is currently evaluating the potential impact that ASU 2016-09 may have on the Company’s financial position or results of operations.

The Company did not adopt any new accounting pronouncements during the three and six months ended June 30, 2016 that had an effect on the Company’s condensed consolidated financial statements.

XML

Fair Value of Financial Instruments

6 Months Ended

Jun. 30, 2016

Fair Value Disclosures [Abstract]

Fair Value of Financial Instruments

3. Fair Value of Financial Instruments

Financial instruments, including cash, restricted cash, prepaid expenses and other current assets, accounts payable and accrued expenses are presented in the condensed consolidated financial statements at amounts that approximate fair value at June 30, 2016 and December 31, 2015.

The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. The fair value hierarchy prioritizes valuation inputs based on the observable nature of those inputs. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments and is not a measure of the investment credit quality. The hierarchy defines three levels of valuation inputs:

Level 1 inputs	Quoted prices in active markets for identical assets or liabilities
Level 2 inputs	Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly
Level 3 inputs	Unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability

Items classified as Level 2 within the valuation hierarchy consist of commercial paper, corporate debt securities and U.S. government agency securities. The Company estimates the fair values of these marketable securities by taking into consideration valuations obtained from third-party pricing sources. These pricing sources utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include market pricing based on real-time trade data for the same or similar securities, issuer credit spreads, benchmark yields, and other observable inputs. The Company validates the prices provided by its third-party pricing sources by understanding the models used, obtaining market values from other pricing sources and analyzing pricing data in certain instances.

The following table presents information about the Company’s financial assets that have been measured at fair value at June 30, 2016 and indicates the fair value hierarchy of the valuation inputs utilized to determine such fair value (in thousands):

Description	Total		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Financial assets
Cash equivalents:
Money market funds	$	27,213	$	27,213	$	—	$	—
Investments:
Current:
Corporate debt securities		63,284		—		63,284		—
Commercial paper		20,733		—		20,733		—
U.S. government and agency securities		1,001		—		1,001		—
Non-current:
Corporate debt securities (one to two year maturity)		38,433		—		38,433		—
U.S. government and agency securities (one to two year maturity)		4,501		—		4,501		—
	$	155,165	$	27,213	$	127,952	$	—

The following table presents information about the Company’s financial assets that have been measured at fair value at December 31, 2015 and indicates the fair value hierarchy of the valuation inputs utilized to determine such fair value (in thousands):

Description	Total		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Financial assets
Cash equivalents:
Money market funds	$	49,172	$	49,172	$	—	$	—
Investments:
Current:
Corporate debt securities		86,447		—		86,447		—
Commercial paper		29,828		—		29,828		—
U.S. government and agency securities		1,000		—		1,000		—
Non-current:
Corporate debt securities (one to two year maturity)		33,878		—		33,878		—
	$	200,325	$	49,172	$	151,153	$	—

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Investments

6 Months Ended

Jun. 30, 2016

Schedule of Investments [Abstract]

Investments

4. Investments

The following table summarizes the Company’s investments as of June 30, 2016 (in thousands):

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Loss			Fair Value
Current:
Corporate debt securities	$	63,265	$	31	$	(12	)	$	63,284
Commercial paper		20,697		36		—			20,733
U.S. government and agency securities		1,000		1		—			1,001
Non-current:
Corporate debt securities (one to two year maturity)		38,273		160		—			38,433
U.S. government and agency securities (one to two year maturity)		4,500		1		—			4,501
	$	127,735	$	229	$	(12	)	$	127,952

The following table summarizes the Company’s investments as of December 31, 2015 (in thousands):

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Loss			Fair Value
Current:
Corporate debt securities	$	86,515	$	4	$	(72	)	$	86,447
Commercial paper		29,808		20		—			29,828
U.S. government and agency securities		1,000		—		—			1,000
Non-current:
Corporate debt securities (one to two year maturity)		34,019		2		(143	)		33,878
	$	151,342	$	26	$	(215	)	$	151,153

At June 30, 2016 and December 31, 2015, the Company held 19 and 69 debt securities that were in an unrealized loss position for less than one year, respectively. The aggregate fair value of debt securities in an unrealized loss position at June 30, 2016 and December 31, 2015 was $25,406 and $117,851, respectively. There were no individual securities that were in a significant unrealized loss position or that had been in an unrealized loss position for greater than one year as of June 30, 2016 or December 31, 2015.

The Company reviews investments for other-than-temporary impairment whenever the fair value of an investment is less than the amortized cost and evidence indicates that an investment’s carrying amount is not recoverable within a reasonable period of time.

Other-than-temporary impairments of investments are recognized in the condensed consolidated statements of operations if the Company has experienced a credit loss and has the intent to sell the investment or if it is more likely than not that the Company will be required to sell the investment before recovery of the amortized cost basis. Evidence considered in this assessment includes reasons for the impairment, compliance with the Company’s investment policy, the severity and the duration of the impairment and changes in value subsequent to the end of the period.

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Property and Equipment, net

6 Months Ended

Jun. 30, 2016

Property, Plant and Equipment [Abstract]

Property and Equipment, net

5. Property and Equipment, net

Property and equipment, net consists of the following (in thousands):

	Estimated Useful Life Years		June 30, 2016			December 31, 2015
Laboratory equipment		4	$	538		$	538
Furniture and fixtures		5		361			322
Office and computer equipment		3		360			360
Leasehold improvements		Lesser of useful life or lease term		3,397			3,391
				4,656			4,611
Less accumulated depreciation and amortization				(1,486	)		(1,128	)
			$	3,170		$	3,483

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Accrued Expenses

6 Months Ended

Jun. 30, 2016

Text Block [Abstract]

Accrued Expenses

6. Accrued Expenses

Accrued expenses consists of the following (in thousands):

	June 30, 2016		December 31, 2015
Research and development costs	$	8,193	$	8,007
Payroll and employee-related costs		2,099		2,445
Professional fees		462		270
Other		358		301
	$	11,112	$	11,023

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Net Loss Per Share

6 Months Ended

Jun. 30, 2016

Earnings Per Share [Abstract]

Net Loss Per Share

7. Net Loss Per Share

Basic and diluted net loss per common share is calculated by dividing net loss by the weighted-average number of common shares outstanding during the period, without consideration for common stock equivalents. The Company’s potentially dilutive shares, which include outstanding stock options and unvested restricted stock and restricted stock units, are considered to be common stock equivalents and are only included in the calculation of diluted net loss per share when their effect is dilutive.

The following potentially dilutive securities were excluded from the calculation of diluted net loss per share due to their anti-dilutive effect:

	Three and Six Months Ended June 30,
	2016		2015
Outstanding stock options		5,421,363		4,326,014
Unvested restricted stock		—		1,421
Unvested restricted stock units		479,000		—

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Stock-based Compensation

6 Months Ended

Jun. 30, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-based Compensation

8. Stock-based Compensation

Stock options

A summary of the Company’s stock option activity and related information follows:

	Shares			Weighted- Average Exercise Price Per Share		Weighted- Average Remaining Contractual Term (years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2015		4,443,317		$	19.91		8.2	$	15,598
Granted		1,268,400			7.00
Exercised		(62,001	)		3.80
Canceled		(228,353	)		16.88
Outstanding at June 30, 2016		5,421,363		$	17.20		8.1	$	4,986
Exercisable at June 30, 2016		2,324,861		$	16.71		7.3	$	4,104
Vested and expected to vest at June 30, 2016		5,080,019		$	17.37		8.0	$	4,943

As of June 30, 2016, there was $33,944 of total unrecognized stock-based compensation expense related to stock options. The expense is expected to be recognized over a weighted-average period of 2.6 years.

Restricted stock units

A restricted stock unit (“RSU”) represents the right to receive one share of the Company’s common stock upon vesting of the RSU. The fair value of each RSU is based on the closing price of the Company’s common stock on the date of grant. In November 2015, the Company granted RSUs with service conditions that vest in two equal annual installments provided that the employee remains employed with the Company. The following is a summary of RSU activity under the 2013 Plan for the six months ended June 30, 2016:

	Number of Shares Underlying RSUs			Weighted-Average Grant Date Fair Value
Unvested at December 31, 2015		508,800		$	17.39
Granted		25,000			8.06
Forfeited		(17,800	)		17.91
Vested		(37,000	)		11.25
Unvested at June 30, 2016		479,000		$	17.36

The total expense related to RSUs for the six months ended June 30, 2016 and 2015 was $2,367 and $0, respectively. As of June 30, 2016, $5,421 of unrecognized compensation costs related to unvested RSUs are expected to be recognized over a weighted-average period of 1.35 years.

Employee Stock Purchase Plan

The Company has an Employee Stock Purchase Plan (“ESPP”) that permits eligible employees to enroll in a twelve-month offering period comprising two six-month purchase periods. Participants may purchase shares of the Company’s common stock, through payroll deductions, at a price equal to 85% of the fair market value of the common stock on the first day of the applicable six-month offering period or the last day of the applicable six-month purchase period, whichever is lower. Purchase dates under the ESPP occur on or about May 1 and November 1 of each year. In 2013, the Company’s stockholders approved the reservation of 242,424 shares of the Company’s common stock for issuance under the ESPP, plus an annual increase to be added on the first day of each fiscal year, commencing on January 1, 2015 and ending on December 31, 2023, equal to the lesser of 484,848 shares of the Company’s common stock, 1% of the number of outstanding shares on such date, or an amount determined by the board of directors.

For the six months ended June 30, 2016 and 2015, the Company withheld $235 and $125, respectively, from employees on an after tax basis related to the purchase of 29,724 and 5,403 shares, respectively, of the Company’s stock under the ESPP.

For the six months ended June 30, 2016 and 2015, the Company recorded stock-based compensation expense related to the ESPP of $116 and $78, respectively. As of June 30, 2016, 508,184 shares of the Company’s common stock remain available for issuance under the ESPP. As of June 30, 2016, there was $73 of total unrecognized stock-based compensation expense related to the ESPP. The expense is expected to be recognized over a period of four months. 

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Commitments and Contingencies

6 Months Ended

Jun. 30, 2016

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

9. Commitments and Contingencies

In March 2014, the Company entered into an operating lease for approximately 29,933 square feet of office and research space in Newton, Massachusetts. The Company uses the leased premises as its corporate headquarters and for research and development purposes. The lease was amended on December 31, 2014 by extending the lease term of the lease from November 30, 2021 to September 30, 2022. The amendment provides for the expansion of the premises leased by the Company by approximately 16,234 square feet, and provides the Company with the rights of first offer to lease approximately 27,701 square feet of additional space. The Company may extend the lease term for one additional five year period. The Company is recording rent expense on a straight-line basis through the end of the lease term, inclusive of the period in which there are no scheduled rent payments. The Company has recorded deferred rent on the condensed consolidated balance sheets at June 30, 2016 and December 31, 2015, accordingly. The lease provides the Company with an allowance for improvements of $1,616, all of which was incurred through June 30, 2016. All improvements were deemed normal tenant improvements, were recorded as leasehold improvements and deferred rent and will be recorded as a reduction to rent expense ratably over the lease term. The Company has provided a security deposit in the form of a cash-collateralized letter of credit in the amount of $400, which amount may be reduced to $200 in January 2018. The amount is classified as restricted cash on the condensed consolidated balance sheet.

In November 2014, the Company signed a five-year operating lease agreement in Munich, Germany for approximately 3,681 square feet of office space. The lease is for the period February 2015 through January 2020. Pursuant to the lease agreement, the Company is obligated to make aggregate rent payments of €374 (approximately $414), through January 31, 2020. The Company is recording rent expense on a straight-line basis through the end of the lease term, inclusive of the period in which there are no scheduled rent payments.

The Company recorded rent expense totaling $290 and $240 for the three months ended June 30, 2016 and 2015, respectively, and $579 and $464 for the six months ended June 30, 2016 and 2015, respectively.

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Equity

6 Months Ended

Jun. 30, 2016

Equity [Abstract]

Equity

10. Equity

Controlled Equity Offering Sales Agreement

On December 7, 2015, the Company entered into a Controlled Equity Offering Sales Agreement (the “Agreement”), with Cantor Fitzgerald & Co., as sales agent (“Cantor”), pursuant to which the Company may issue and sell, from time to time, through Cantor, shares of the Company’s common stock, up to an aggregate offering price of $50.0 million (the “Shares”).

Under the Agreement, Cantor may sell the Shares by methods deemed to be an “at-the-market” offering as defined in Rule 415 promulgated under the Securities Act of 1933, as amended (the “Securities Act”), including sales made directly on The NASDAQ Global Select Market, on any other existing trading market for the Shares or to or through a market maker. In addition, under the Agreement, Cantor may sell the Shares by any other method permitted by law, including in privately negotiated transactions.

The Company is not obligated to make any sales of the Shares under the Agreement. The Company or Cantor may suspend or terminate the offering of Shares upon notice to the other party and subject to other conditions. The Company will pay Cantor a commission of up to 3.0% of the gross proceeds from the sale of the Shares pursuant to the Agreement and has agreed to provide Cantor with customary indemnification and contribution rights.

In December 2015, the Company sold an aggregate of 121,314 shares under the Agreement, for net proceeds of approximately $1.5 million. As of July 31, 2016, the Company has not sold any additional shares under the Agreement.

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Summary of Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2016

Accounting Policies [Abstract]

Basis of Presentation

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements of Karyopharm Therapeutics Inc. (the “Company”) have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial reporting and as required by Regulation S-X, Rule 10-01. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments (including those which are normal and recurring) considered necessary for a fair presentation of the interim financial information have been included. When preparing financial statements in conformity with GAAP, the Company must make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, expenses and related disclosures at the date of the financial statements. Actual results could differ from those estimates. Additionally, operating results for the three and six months ended June 30, 2016 are not necessarily indicative of the results that may be expected for any other interim period or for the fiscal year ending December 31, 2016. For further information, refer to the financial statements and footnotes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2015 as filed with the Securities and Exchange Commission (“SEC”) on March 15, 2016.

Basis of Consolidation

Basis of Consolidation

The condensed consolidated financial statements at June 30, 2016 include the accounts of Karyopharm Therapeutics Inc. (a Delaware corporation), the accounts of Karyopharm Securities Corp. (a wholly-owned Massachusetts corporation of the Company incorporated in December 2013), the accounts of Karyopharm Europe GmbH (a wholly-owned German Limited Liability Company formed in August 2014), and the accounts of Karyopharm Therapeutics (Bermuda) Ltd. (a wholly-owned Bermuda subsidiary of the Company formed in March 2015). All intercompany balances and transactions have been eliminated in consolidation.

Recently Issued Accounting Pronouncements

2. Recently Issued Accounting Pronouncements

In August 2014, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) No. 2014-15, Presentation of Financial Statements—Going Concern (Subtopic 205-40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern. ASU No. 2014-15 is intended to define management’s responsibility to evaluate whether there is substantial doubt about an organization’s ability to continue as a going concern and to provide related footnote disclosures. Substantial doubt about an entity’s ability to continue as a going concern exists when relevant conditions and events, considered in the aggregate, indicate that it is probable that the entity will be unable to meet its obligations as they become due within one year after the date that the financial statements are issued (or available to be issued). ASU No. 2014-15 provides guidance to an organization’s management, with principles and definitions that are intended to reduce diversity in the timing and content of disclosures that are commonly provided by organizations in the financial statement footnotes. ASU No. 2014-15 is effective for annual reporting periods ending after December 15, 2016, and for annual and interim periods thereafter. Early adoption is permitted. The Company does not expect the adoption of ASU No. 2014-15 to have a material impact on its consolidated financial statements, but it may impact the Company’s disclosures.

In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers, which defers the effective date of ASU 2014-09 for all entities by one year. ASU 2014-09 is now effective for public companies for annual reporting periods beginning after December 15, 2017, including interim periods within those reporting periods. Early adoption is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. ASU 2014-09 outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most of the current revenue recognition guidance, including industry-specific guidance. In addition, ASU 2014-09 provides guidance on accounting for certain revenue-related costs including, but not limited to, when to capitalize costs associated with obtaining and fulfilling a contract. ASU 2014-09 provides companies with two implementation methods. Companies can choose to apply the standard retrospectively to each prior reporting period presented (full retrospective application) or retrospectively with the cumulative effect of initially applying the standard as an adjustment to the opening balance of retained earnings of the annual reporting period that includes the date of initial application (modified retrospective application). The Company continues to evaluate the expected impact of this new guidance and available adoption methods.

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). The new standard requires that all lessees recognize the assets and liabilities that arise from leases on the balance sheet and disclose qualitative and quantitative information about its leasing arrangements. The new standard will be effective for the Company on January 1, 2019. The Company is currently evaluating the potential impact that this standard may have on its consolidated financial statements.

In March 2016, the FASB issued ASU No. 2016-09, Compensation – Stock Compensation (Topic 718). The new standard identifies areas for simplification involving several aspects of accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, an option to recognize gross stock compensation expense with actual forfeitures recognized as they occur, as well as certain classifications on the statement of cash flows. The standard is effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods. Early adoption is permitted. An entity that elects early adoption must adopt all of the provisions of the standard in the same period. The Company is currently evaluating the potential impact that ASU 2016-09 may have on the Company’s financial position or results of operations.

The Company did not adopt any new accounting pronouncements during the three and six months ended June 30, 2016 that had an effect on the Company’s condensed consolidated financial statements.

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Fair Value of Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2016

Fair Value Disclosures [Abstract]

Schedule of Financial Assets That Have Been Measured at Fair Value

The following table presents information about the Company’s financial assets that have been measured at fair value at June 30, 2016 and indicates the fair value hierarchy of the valuation inputs utilized to determine such fair value (in thousands):

Description	Total		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Financial assets
Cash equivalents:
Money market funds	$	27,213	$	27,213	$	—	$	—
Investments:
Current:
Corporate debt securities		63,284		—		63,284		—
Commercial paper		20,733		—		20,733		—
U.S. government and agency securities		1,001		—		1,001		—
Non-current:
Corporate debt securities (one to two year maturity)		38,433		—		38,433		—
U.S. government and agency securities (one to two year maturity)		4,501		—		4,501		—
	$	155,165	$	27,213	$	127,952	$	—

The following table presents information about the Company’s financial assets that have been measured at fair value at December 31, 2015 and indicates the fair value hierarchy of the valuation inputs utilized to determine such fair value (in thousands):

Description	Total		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Financial assets
Cash equivalents:
Money market funds	$	49,172	$	49,172	$	—	$	—
Investments:
Current:
Corporate debt securities		86,447		—		86,447		—
Commercial paper		29,828		—		29,828		—
U.S. government and agency securities		1,000		—		1,000		—
Non-current:
Corporate debt securities (one to two year maturity)		33,878		—		33,878		—
	$	200,325	$	49,172	$	151,153	$	—

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Investments (Tables)

6 Months Ended

Jun. 30, 2016

Schedule of Investments [Abstract]

Summary of Investments

The following table summarizes the Company’s investments as of June 30, 2016 (in thousands):

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Loss			Fair Value
Current:
Corporate debt securities	$	63,265	$	31	$	(12	)	$	63,284
Commercial paper		20,697		36		—			20,733
U.S. government and agency securities		1,000		1		—			1,001
Non-current:
Corporate debt securities (one to two year maturity)		38,273		160		—			38,433
U.S. government and agency securities (one to two year maturity)		4,500		1		—			4,501
	$	127,735	$	229	$	(12	)	$	127,952

The following table summarizes the Company’s investments as of December 31, 2015 (in thousands):

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Loss			Fair Value
Current:
Corporate debt securities	$	86,515	$	4	$	(72	)	$	86,447
Commercial paper		29,808		20		—			29,828
U.S. government and agency securities		1,000		—		—			1,000
Non-current:
Corporate debt securities (one to two year maturity)		34,019		2		(143	)		33,878
	$	151,342	$	26	$	(215	)	$	151,153

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Property and Equipment, net (Tables)

6 Months Ended

Jun. 30, 2016

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment, Net

Property and equipment, net consists of the following (in thousands):

	Estimated Useful Life Years		June 30, 2016			December 31, 2015
Laboratory equipment		4	$	538		$	538
Furniture and fixtures		5		361			322
Office and computer equipment		3		360			360
Leasehold improvements		Lesser of useful life or lease term		3,397			3,391
				4,656			4,611
Less accumulated depreciation and amortization				(1,486	)		(1,128	)
			$	3,170		$	3,483

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Accrued Expenses (Tables)

6 Months Ended

Jun. 30, 2016

Text Block [Abstract]

Schedule of Accrued Expenses

Accrued expenses consists of the following (in thousands):

	June 30, 2016		December 31, 2015
Research and development costs	$	8,193	$	8,007
Payroll and employee-related costs		2,099		2,445
Professional fees		462		270
Other		358		301
	$	11,112	$	11,023

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Net Loss Per Share (Tables)

6 Months Ended

Jun. 30, 2016

Earnings Per Share [Abstract]

Schedule of Potentially Dilutive Securities Were Excluded From The Calculation of Diluted Net Loss Per Share Due to Their Anti-Dilutive Effect

The following potentially dilutive securities were excluded from the calculation of diluted net loss per share due to their anti-dilutive effect:

	Three and Six Months Ended June 30,
	2016		2015
Outstanding stock options		5,421,363		4,326,014
Unvested restricted stock		—		1,421
Unvested restricted stock units		479,000		—

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Stock-based Compensation (Tables)

6 Months Ended

Jun. 30, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of Stock Option Activity for Employees and Nonemployees

A summary of the Company’s stock option activity and related information follows:

	Shares			Weighted- Average Exercise Price Per Share		Weighted- Average Remaining Contractual Term (years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2015		4,443,317		$	19.91		8.2	$	15,598
Granted		1,268,400			7.00
Exercised		(62,001	)		3.80
Canceled		(228,353	)		16.88
Outstanding at June 30, 2016		5,421,363		$	17.20		8.1	$	4,986
Exercisable at June 30, 2016		2,324,861		$	16.71		7.3	$	4,104
Vested and expected to vest at June 30, 2016		5,080,019		$	17.37		8.0	$	4,943

Summary of RSU Activity

The following is a summary of RSU activity under the 2013 Plan for the six months ended June 30, 2016:

	Number of Shares Underlying RSUs			Weighted-Average Grant Date Fair Value
Unvested at December 31, 2015		508,800		$	17.39
Granted		25,000			8.06
Forfeited		(17,800	)		17.91
Vested		(37,000	)		11.25
Unvested at June 30, 2016		479,000		$	17.36

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Fair Value of Financial Instruments - Schedule of Financial Assets That Have Been Measured at Fair Value (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Financial assets
Total	$ 155,165	$ 200,325
Current [Member] | Corporate Debt Securities [Member]
Financial assets
Investments	63,284	86,447
Current [Member] | Commercial Paper [Member]
Financial assets
Investments	20,733	29,828
Current [Member] | US Government and Agency Securities [Member]
Financial assets
Investments	1,001	1,000
Non-current [Member] | U.S. Government and Agency Securities (One to Two Year Maturity) [Member]
Financial assets
Investments	4,501
Non-current [Member] | Corporate Debt Securities (One to Two Year Maturity) [Member]
Financial assets
Investments	38,433	33,878
Money Market Funds [Member]
Financial assets
Cash equivalents	27,213	49,172
Level 1 [Member]
Financial assets
Total	27,213	49,172
Level 1 [Member] | Money Market Funds [Member]
Financial assets
Cash equivalents	27,213	49,172
Level 2 [Member]
Financial assets
Total	127,952	151,153
Level 2 [Member] | Current [Member] | Corporate Debt Securities [Member]
Financial assets
Investments	63,284	86,447
Level 2 [Member] | Current [Member] | Commercial Paper [Member]
Financial assets
Investments	20,733	29,828
Level 2 [Member] | Current [Member] | US Government and Agency Securities [Member]
Financial assets
Investments	1,001	1,000
Level 2 [Member] | Non-current [Member] | U.S. Government and Agency Securities (One to Two Year Maturity) [Member]
Financial assets
Investments	4,501
Level 2 [Member] | Non-current [Member] | Corporate Debt Securities (One to Two Year Maturity) [Member]
Financial assets
Investments	$ 38,433	$ 33,878

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Investments - Summary of Investments (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Summary of Investment Holdings [Line Items]
Amortized Cost	$ 127,735	$ 151,342
Gross Unrealized Gains	229	26
Gross Unrealized Loss	(12)	(215)
Fair Value	127,952	151,153
Current [Member] | Corporate Debt Securities [Member]
Summary of Investment Holdings [Line Items]
Amortized Cost	63,265	86,515
Gross Unrealized Gains	31	4
Gross Unrealized Loss	(12)	(72)
Fair Value	63,284	86,447
Current [Member] | Commercial Paper [Member]
Summary of Investment Holdings [Line Items]
Amortized Cost	20,697	29,808
Gross Unrealized Gains	36	20
Fair Value	20,733	29,828
Current [Member] | US Government and Agency Securities [Member]
Summary of Investment Holdings [Line Items]
Amortized Cost	1,000	1,000
Gross Unrealized Gains	1
Fair Value	1,001	1,000
Non-current [Member] | U.S. Government and Agency Securities (One to Two Year Maturity) [Member]
Summary of Investment Holdings [Line Items]
Amortized Cost	4,500
Gross Unrealized Gains	1
Fair Value	4,501
Non-current [Member] | Corporate Debt Securities (One to Two Year Maturity) [Member]
Summary of Investment Holdings [Line Items]
Amortized Cost	38,273	34,019
Gross Unrealized Gains	160	2
Gross Unrealized Loss		(143)
Fair Value	$ 38,433	$ 33,878

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Investments - Additional Information (Detail) $ in Thousands	Jun. 30, 2016 USD ($) Securities	Dec. 31, 2015 USD ($) Securities
Investments, Debt and Equity Securities [Abstract]
Number of debt securities with unrealized loss position for less than one year	19	69
Aggregate fair value of debt securities | $	$ 25,406	$ 117,851
Number of debt securities with unrealized loss position for greater than one year	0	0

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Property and Equipment, net - Schedule of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 4,656	$ 4,611
Less accumulated depreciation and amortization	(1,486)	(1,128)
Property and equipment, net	$ 3,170	3,483
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	4 years
Property and equipment, gross	$ 538	538
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Property and equipment, gross	$ 361	322
Office and Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Property and equipment, gross	$ 360	360
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 3,397	$ 3,391

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Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Accrued Liabilities, Current [Abstract]
Research and development costs	$ 8,193	$ 8,007
Payroll and employee-related costs	2,099	2,445
Professional fees	462	270
Other	358	301
Total Accrued Expenses	$ 11,112	$ 11,023

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Net Loss Per Share - Schedule of Potentially Dilutive Securities Were Excluded From The Calculation of Diluted Net Loss Per Share Due to Their Anti-Dilutive Effect (Detail) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Outstanding Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Dilutive securities excluded from the calculation of diluted net loss per share due to anti-dilutive effect (in shares)	5,421,363	4,326,014	5,421,363	4,326,014
Unvested Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Dilutive securities excluded from the calculation of diluted net loss per share due to anti-dilutive effect (in shares)		1,421		1,421
Unvested Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Dilutive securities excluded from the calculation of diluted net loss per share due to anti-dilutive effect (in shares)	479,000		479,000

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Stock-based Compensation - Summary of Stock Option Activity for Employees and Nonemployees (Detail) - Employee and Nonemployee Stock Option [Member] - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option activity, shares outstanding, at beginning of period	4,443,317
Stock option activity, shares granted	1,268,400
Stock option activity, shares exercised	(62,001)
Stock option activity, shares canceled	(228,353)
Stock option activity, shares outstanding, at end of period	5,421,363	4,443,317
Stock option activity, exercisable at end of period	2,324,861
Stock option activity, vested or expected to vest at end of period	5,080,019
Weighted average exercise price, options outstanding at beginning of period	$ 19.91
Weighted average exercise price, options granted	7.00
Weighted average exercise price, option exercised	3.80
Weighted average exercise price, option canceled	16.88
Weighted average exercise price, options outstanding at end of period	17.20	$ 19.91
Weighted average exercise price, options exercisable at end of period	16.71
Weighted average exercise price, option vested and expected to vest at the end of period	$ 17.37
Weighted average remaining contractual life outstanding	8 years 1 month 6 days	8 years 2 months 12 days
Weighted average exercise price exercisable	7 years 3 months 18 days
Weighted average exercise price vested or expected to vest	8 years
Aggregate intrinsic value outstanding	$ 4,986	$ 15,598
Aggregate intrinsic value exercisable	4,104
Aggregate intrinsic value vested or expected to vest	$ 4,943

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Stock-based Compensation - Additional Information (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2016 USD ($) PurchasePeriod shares	Jun. 30, 2015 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee stock purchase plan, amount withheld from employees	$ 235	$ 125
Common stock available for payment related to tax withholding | shares	29,724	5,403
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized stock-based compensation expense	$ 33,944
Period for recognition of unrecognized expense	2 years 7 months 6 days
Unvested Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized stock-based compensation expense	$ 5,421
Period for recognition of unrecognized expense	1 year 4 months 6 days
Right to received shares of common stock (shares)	1
Stock based compensation expense	$ 2,367	$ 0
ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized stock-based compensation expense	$ 73
Period for recognition of unrecognized expense	4 months
Stock based compensation expense	$ 116	$ 78
Offering period	12 months
Number of purchase period | PurchasePeriod	2
Purchase period	6 months
Purchase price of common stock	85.00%
Number of shares of common stock authorized | shares	242,424
Common stock shares available for issuance under ESPP | shares	508,184
Percentage of shares of common stock available for issuance	1.00%
Employee stock purchase plan, description	In 2013, the Company's stockholders approved the reservation of 242,424 shares of the Company's common stock for issuance under the ESPP, plus an annual increase to be added on the first day of each fiscal year, commencing on January 1, 2015 and ending on December 31, 2023, equal to the lesser of 484,848 shares of the Company's common stock, 1% of the number of outstanding shares on such date, or an amount determined by the board of directors.
ESPP [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares available for issuance under ESPP | shares	484,848

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Stock-based Compensation - Summary of RSU Activity (Detail) - Unvested Restricted Stock Units [Member]	6 Months Ended
	Jun. 30, 2016 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares underlying RSUs, Unvested beginning balance | shares	508,800
Number of shares underlying RSUs, Granted | shares	25,000
Number of shares underlying RSUs, Forfeited | shares	(17,800)
Number of shares underlying RSUs, Vested | shares	(37,000)
Number of shares underlying RSUs, Unvested ending balance | shares	479,000
Weighted-Average grant date fair value, Unvested beginning balance | $ / shares	$ 17.39
Weighted-Average grant date fair value, Granted | $ / shares	8.06
Weighted-Average grant date fair value, Forfeited | $ / shares	17.91
Weighted-Average grant date fair value, Vested | $ / shares	11.25
Weighted-Average grant date fair value, Unvested ending balance | $ / shares	$ 17.36

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Commitments and Contingencies - Additional Information (Detail) € in Thousands, $ in Thousands	1 Months Ended		3 Months Ended		6 Months Ended
	Nov. 30, 2014 EUR (€) ft²	Mar. 31, 2014 USD ($) ft² Lease	Jun. 30, 2016 USD ($) ft²	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) ft²	Jun. 30, 2015 USD ($)	Nov. 30, 2014 USD ($) ft²
Commitments and Contingencies Disclosure [Abstract]
Office and laboratory space leased | ft²	3,681	29,933					3,681
Number of additional lease term | Lease		1
Additional extension term of lease		5 years
Allowance for improvements					$ 1,616
Security deposit in the form of a letter of credit		$ 400
Security deposit in the form of a letter of credit which may be reduced in January 2018		$ 200
Operating lease amendment, leased premises expansion | ft²			16,234		16,234
Operating lease amendment, additional space | ft²			27,701		27,701
Operating lease agreement term	5 years
Scheduled rent payments due	€ 374						$ 414
Total rent expense			$ 290	$ 240	$ 579	$ 464

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Equity - Controlled Equity Offering Sales Agreement - Additional Information (Detail) - Cantor Fitzgerald & Co. [Member] - Controlled Equity Offering Sales Agreement [Member] - USD ($)		1 Months Ended	6 Months Ended
	Jul. 31, 2016	Dec. 31, 2015	Jun. 30, 2016	Dec. 07, 2015
Common Stock [Member]
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award Options [Line Items]
Issuance of common stock, net of issuance costs		121,314
Net proceeds from sale of common stock		$ 1,500,000
Subsequent Event [Member] | Common Stock [Member]
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award Options [Line Items]
Issuance of common stock, net of issuance costs	0
Maximum [Member]
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award Options [Line Items]
Aggregate offering price				$ 50,000,000
Percentage of commission of gross proceeds from the sale of Shares			3.00%