10-K/A

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, DC 20549

FORM 10-K/A

(Amendment No. 1)

(Mark One)

    ☒

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

For the fiscal year ended December 31, 2020

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: 001-37467

Catabasis Pharmaceuticals, Inc.

(Exact name of registrant as specified in its charter)

Delaware (State or other jurisdiction of
incorporation or organization) 26-3687168 (IRS Employer
Identification No.)

100 High Street
Floor 28
Boston, Massachusetts (Address of principal executive offices) 02110 (Zip Code)

Registrant’s telephone number, including area code (617) 349-1971

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Common Stock, $0.001 par value per share	CATB	Nasdaq Global Market

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. ☐ Yes ☒ No

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. ☐ Yes ☒ No

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 ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted 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 such files).  Yes ☒ No ☐

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

Large accelerated filer ☐	Accelerated filer ☐	Non-accelerated filer ☒	Smaller reporting company ☒
​	​	​	Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. ☐

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

Aggregate market value of the voting and non-voting common equity held by non-affiliates of the registrant, based on the last sale price for such stock on June 30, 2020: $101,269,279

As of March 4, 2021, there were 23,417,006 shares of the registrant’s common stock, par value $0.001 per share, outstanding.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the registrant’s definitive proxy statement relating to its 2021 Annual Meeting of Stockholders are incorporated by reference into Part III of this Annual Report on Form 10-K where indicated. The registrant intends to file such proxy statement with the U.S. Securities and Exchange Commission within 120 days after the end of the fiscal year to which this Annual Report on Form 10-K relates.

EXPLANATORY NOTE

This Amendment No. 1 to the Annual Report on Form 10-K is being filed solely to furnish the Interactive Data files as Exhibit 101, in accordance with Rule 405 of Regulation S-T. No other changes have been made to the Form 10-K, as originally filed on March 11, 2021.

PART IV

Item 15.

Exhibits and Financial Statement Schedules

Exhibit Number	Description of Exhibit
101.INS	XBRL Instance Document
101.SCH	XBRL Taxonomy Extension Schema Document
101.CAL	XBRL Taxonomy Calculation Linkbase
101.LAB	XBRL Taxonomy Labels Linkbase Document
101.PRE	XBRL Taxonomy Presentation Linkbase Document
101.DEF	Taxonomy Extension Definition Linkbase Document

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) 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.

Catabasis Pharmaceuticals, Inc.

Date: April 19, 2021
By:
/s/ Jill C. Milne

Jill C. Milne

President and Chief Executive Officer

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Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2020	Mar. 04, 2021	Jun. 30, 2020
Document and Entity Information
Entity Registrant Name	CATABASIS PHARMACEUTICALS INC
Document Type	10-K/A
Document Period End Date	Dec. 31, 2020
Title of 12(b) Security	Common Stock, $0.001 par value per share
Trading Symbol	CATB
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		23,417,006
Entity Public Float			$ 101,269,279
Entity Central Index Key	0001454789
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false

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Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 24,930	$ 9,899
Short-term investments	20,000	26,345
Prepaid expenses and other current assets	1,395	2,714
Total current assets	46,325	38,958
Right-of-use asset	966	2,349
Other assets	165	473
Total assets	47,456	41,780
Current liabilities:
Accounts payable	1,544	1,197
Accrued expenses	4,197	2,610
Current portion of operating lease liabilities	649	1,225
Total current liabilities	6,390	5,032
Long-term portion of operating lease liabilities	397	1,028
Total liabilities	6,787	6,060
Commitments (Note 6)
Stockholders' equity:
Preferred stock, $0.001 par value per share, 5,000,000 shares authorized and no shares issued and outstanding
Common stock, $0.001 par value per share, 150,000,000 shares authorized; 20,084,337 and 12,433,600 shares issued and outstanding at December 31, 2020 and December 31, 2019, respectively	20	12
Additional paid-in capital	301,546	259,305
Accumulated deficit	(260,897)	(223,597)
Total stockholders' equity	40,669	35,720
Total liabilities and stockholders' equity	$ 47,456	$ 41,780

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Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Consolidated Balance Sheets
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, authorized (in shares)	5,000,000	5,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized (in shares)	150,000,000	150,000,000
Common stock, issued (in shares)	20,084,337	12,433,600
Common stock, outstanding (in shares)	20,084,337	12,433,600

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Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Operating expenses:
Research and development	$ 25,590	$ 18,317
General and administrative	11,845	8,771
Total operating expenses	37,435	27,088
Loss from operations	(37,435)	(27,088)
Other income (expense):
Interest and investment income	236	845
Other expense, net	(101)	(50)
Total other income, net	135	795
Net loss	$ (37,300)	$ (26,293)
Net loss per share - basic and diluted (in dollars per share)	$ (2.03)	$ (2.35)
Weighted-average common shares outstanding used in net loss per share - basic and diluted (in shares)	18,351,470	11,199,057

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Consolidated Statements Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Consolidated Statements Comprehensive Loss
Net loss	$ (37,300)	$ (26,293)
Other comprehensive income:
Gain on short-term investments		4
Total other comprehensive income:		4
Comprehensive loss	$ (37,300)	$ (26,289)

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Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive (Loss) Gain	Total
Balance at Dec. 31, 2018	$ 7	$ 232,243	$ (197,304)	$ (4)	$ 34,942
Balance (in shares) at Dec. 31, 2018	7,141,996
Increase (Decrease) in Shareholders' Equity
Issuance of common stock and warrants in public offerings, net of issuance costs	$ 4	18,501			18,505
Issuance of common stock and warrants in public offerings, net of issuance costs (in shares)	4,000,000
Issuance of common stock for at-the-market offerings, net of issuance costs	$ 1	6,995			6,996
Issuance of common stock for at-the-market offerings, net of issuance costs of (in shares)	1,282,904
Proceeds from exercises of warrants		54			54
Proceeds from exercises of warrants (in shares)	8,700
Stock-based compensation expense		1,512			1,512
Unrealized gain on short-term investments				$ 4	4
Net loss			(26,293)		(26,293)
Balance at Dec. 31, 2019	$ 12	259,305	(223,597)		$ 35,720
Balance (in shares) at Dec. 31, 2019	12,433,600				12,433,600
Increase (Decrease) in Shareholders' Equity
Issuance of common stock and warrants in public offerings, net of issuance costs	$ 5	24,554			$ 24,559
Issuance of common stock and warrants in public offerings, net of issuance costs (in shares)	5,290,000
Issuance of common stock for at-the-market offerings, net of issuance costs	$ 3	16,267			16,270
Issuance of common stock for at-the-market offerings, net of issuance costs of (in shares)	2,353,737
Proceeds from exercises of warrants		31			31
Proceeds from exercises of warrants (in shares)	7,000
Stock-based compensation expense		1,389			1,389
Net loss			(37,300)		(37,300)
Balance at Dec. 31, 2020	$ 20	$ 301,546	$ (260,897)		$ 40,669
Balance (in shares) at Dec. 31, 2020	20,084,337				20,084,337

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Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Issuance of common stock and warrants in public offering
Stock issuance costs	$ 1.9	$ 1.5
ATM
Stock issuance costs	$ 0.5	$ 0.4

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Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Operating activities
Net loss	$ (37,300)	$ (26,293)
Reconciliation of net loss to net cash used in operating activities:
Non-cash items	1,448	1,594
Changes in assets and liabilities:
Prepaid expenses and other current assets	1,172	(1,289)
Other assets	85
Right-of-use asset-operating	176	(96)
Accounts payable	347	(211)
Accrued expenses	1,587	(205)
Other liabilities		(69)
Net cash used in operating activities	(32,485)	(26,569)
Investing activities
Purchases of short-term investments	(62,777)	(155,197)
Sales and maturities of short-term investments	69,110	151,127
Purchases of property and equipment	(33)	(12)
Net cash provided by (used in) investing activities	6,300	(4,082)
Financing activities
Proceeds from public offerings, net of issuance costs	24,559	18,505
Proceeds from at-the-market offering, net of issuance costs	16,270	7,061
Proceeds from exercise of common stock options and warrants	31	54
Net cash provided by financing activities	40,860	25,620
Net increase (decrease) in cash, cash equivalents and restricted cash	14,675	(5,031)
Cash, cash equivalents and restricted cash, beginning of period	10,376	15,407
Cash, cash equivalents and restricted cash, end of period	$ 25,051	10,376
Non-cash financing activities:
At-the-market offering issuance costs included in current liabilities		$ 65

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Organization and Operations

12 Months Ended

Dec. 31, 2020

Organization and Operations

Organization and Operations

1.Organization and Operations

The Company

Catabasis Pharmaceuticals, Inc (the “Company”) is a biopharmaceutical company focused on the discovery, development and commercialization of novel therapeutics. Its mission is to bring hope with life-changing therapies to patients and families that are affected by rare diseases. On October 26, 2020, the Company announced that the Phase 3 PolarisDMD trial of the Company's previous lead product candidate, edasalonexent, for the treatment of Duchenne muscular dystrophy (DMD) did not meet its primary and secondary endpoints. Based on these results, the Company announced that it was stopping activities related to the development of edasalonexent, including the Company's ongoing open-label extension trial. On January 28, 2021, the Company acquired Quellis Biosciences, Inc ("Quellis"). The Company's lead product candidate, which was acquired in the Quellis acquisition, is QLS-215, a monoclonal antibody inhibitor of plasma kallikrein in preclinical development for the treatment of hereditary angioedema, or HAE, a rare, debilitating and potentially life-threatening disease. The Company was incorporated in the State of Delaware on June 26, 2008.

Liquidity

The Company has entered into various sales agreements with Cowen and Company LLC, (“Cowen”), pursuant to which the Company could issue and sell shares of common stock under at-the-market offering programs (the “ATM Programs”). Shares sold pursuant to these sales agreements were sold pursuant to shelf registration statements, one of which became effective on July 19, 2016 and which was replaced by a new shelf registration statement, which became effective May 22, 2019. The Company pays Cowen 3% of the gross proceeds from any common stock sold through these sales agreements. The Company currently has $27.9 million remaining available under its sales agreement.

During the year ended December 31, 2020, the Company sold an aggregate of 2,353,737 shares of common stock pursuant to the ATM Programs, at an average price of $7.13 per share, for gross proceeds of $16.8 million, resulting in net proceeds of $16.3 million after deducting sales commissions and offering expenses.

On January 30, 2020, the Company entered into an underwriting agreement with Oppenheimer & Co. Inc. relating to an underwritten public offering (the “January 2020 Financing”) of 5,290,000 shares of common stock at a price to the public of $5.00 per share. This resulted in gross proceeds of $26.5 million, and net proceeds of $24.6 million.

On February 6, 2019, the Company entered into an underwriting agreement with Oppenheimer & Co. Inc. relating to an underwritten public offering (the “February 2019 Financing”) of 4,000,000 shares of common stock and accompanying warrants to purchase up to 2,000,000 shares of common stock, at a combined price to the public of $5.00 per unit, for gross proceeds of $20.0 million and net proceeds of $18.5 million.

The Company is subject to a number of risks similar to other life science companies, including, but not limited to, successful discovery and development of its drug candidates, raising additional capital, development by its competitors of new technological innovations, protection of proprietary technology and regulatory approval and market acceptance of the Company's products. The Company has been primarily involved with research and development activities and has incurred operating losses and negative cash flows from operations since its inception. The Company anticipates that it will continue to incur significant operating losses for the next several years as it continues to develop its product candidates.

As of December 31, 2020, the Company had an accumulated deficit of $260.9 million. The Company will require substantial additional capital to fund operations. The Company has not generated any product revenues and has financed its operations primarily through public offerings and private placements of its equity securities. There can be no assurance that the Company will be able to obtain additional debt or equity financing or generate product revenue or revenues from collaborative partners, on terms acceptable to the Company, on a timely basis or at all. The failure of the Company to obtain sufficient funds on acceptable terms when needed could have a material adverse effect on the Company's business, results of operations, and financial condition.

As of December 31, 2020, the Company had available cash, cash equivalents and short-term investments of $44.9 million. Subsequent to December 31, 2020, the Company raised gross proceeds of $110.0 million, and net proceeds of $104.0 million, through the February 2021 Financing (as described below). As part of the Quellis acquisition and the February 2021 Financing, the Company issued 86,077 shares of Series X Preferred Stock, which upon stockholder approval can be converted to 86,077,000 shares of common stock. The terms of the Series X Preferred Stock include a cash redemption feature.  The redemption feature provides that, if the Company’s common stockholders fail to approve the ability of the holders of the Series X Preferred Stock to convert their respective shares into common stock by July 28, 2021,  the Company could, at the holder’s option, be required to make a redemption payment to the holders of Series X Preferred Stock based on the then fair value of the Company’s common stock underlying the redeemed Series X Preferred Stock significantly in excess of current liquidity. Based on precedent transactions and the terms of the Series X Preferred Stock, the Company believes that stockholders who are entitled to vote on the conversion proposal at the Company's 2021 Annual Meeting of Stockholders, which is scheduled for June 2, 2021, will vote to approve the proposal.  However, as the vote of the Company’s common stockholders is outside of the control of the Company, there is substantial doubt about its ability to continue as a going concern for at least 12 months following the issuance of these consolidated financial statements. The accompanying consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the ordinary course of business. The consolidated financial statements do not include any adjustments relating to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of this uncertainty.

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Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2020

Summary of Significant Accounting Policies

Summary of Significant Accounting Policies

2.    Summary of Significant Accounting Policies 

Basis of Presentation and Principles of Consolidation

The accompanying consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary, Catabasis Securities Corporation.  All intercompany balances and transactions have been eliminated in consolidation. These consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”) and include all adjustments necessary for the fair presentation of the Company’s financial position for the periods presented.  

Use of Estimates 

The preparation of the Company’s consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from such estimates.

The Company utilizes certain estimates to record expenses relating to research and development contracts. These contract estimates, which are primarily related to the length of service of each contract and the amount of service provided as of each measurement date, are determined by the Company based on input from internal project management, as well as from third-party service providers.

Off-Balance Sheet Risk and Concentrations of Credit Risk

The Company has no off-balance sheet risk, such as foreign exchange contracts, option contracts or other foreign hedging arrangements. Financial instruments that subject the Company to credit risk primarily consist of cash, cash equivalents, short-term investments and restricted cash. The primary objectives for the Company's investment portfolio are the preservation of capital and the maintenance of liquidity. The Company's investment policy includes guidelines on the quality of the institutions and financial instruments and defines allowable investments that the Company believes minimizes the exposure to concentration of credit risk. 

Cash and Cash Equivalents and Restricted Cash

The Company considers highly liquid investments with a maturity of three months or less or reverse repurchase agreements with a maturity period of one business day or less when purchased to be cash equivalents. Cash equivalents, which consist of money market funds, corporate debt securities and reverse repurchase agreements are stated at fair value. Cash and cash equivalents consist of the following (in thousands):

	December 31,
	2020		2019
Cash	$	1,931	$	2,530
Money market fund		22,999		5,432
Corporate debt securities		—		1,937
Total	$	24,930	$	9,899

The reconciliation of cash, cash equivalents and restricted cash reported within the applicable balance sheet that sum to the total of the same such amount shown in the statement of cash flows is as follows (in thousands):

	December 31,
	2020		2019
Cash and cash equivalents	$	24,930	$	9,899
Restricted cash (1)		121		477
Total	$	25,051	$	10,376

(1) Included in prepaid expenses and other current assets and other assets.

Short-Term Investments

The Company classifies all corporate debt securities with a remaining maturity of greater than three months and reverse repurchase agreements with a remaining maturity of greater than one business day at the time of purchase as short-term investments. Short-term investments are recorded at fair value, with the unrealized gains and losses reported in other comprehensive loss. The amortized cost of debt securities is adjusted for the amortization of premiums and accretion of discounts to maturity. Such amortization is included in interest and investment income. Realized gains and losses, interest, dividends and declines in value judged to be other-than-temporary are included in interest and investment income.

The cost of securities sold is based on the specific identification method for purposes of recording realized gains and losses. To determine whether an other-than-temporary impairment exists, the Company considers whether it has the ability and intent to hold the investment until a market price recovery, and whether evidence indicating the recoverability of the cost of the investment outweighs evidence to the contrary.

Fair Value of Financial Instruments

The fair value hierarchy prioritizes the inputs to valuation techniques used to measure fair value into three broad levels as follows: Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities; Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly; and Level 3 inputs are unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability. Financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement.

The carrying amounts reflected in the balance sheets for cash equivalents, restricted cash, prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair values at December 31, 2020 and 2019, due to their short-term nature. There have been no changes to the valuation methods during the years ended December 31, 2020 and 2019. The Company evaluates transfers between levels at the end of each reporting period. There were no transfers of assets or liabilities between levels during the year ended December 31, 2020 and 2019.

The Company’s investment portfolio may include fixed income securities that do not always trade on a daily basis. As a result, the pricing services used by the Company apply other available information as applicable through processes such as benchmark yields, benchmarking of like securities, sector groupings and matrix pricing to prepare valuations. The Company validates the prices provided by its third party pricing services by obtaining market values from other pricing sources and analyzing pricing data in certain instances. The Company also invests in certain reverse repurchase agreements which are collateralized by deposits in the form of United States Government Securities and Obligations for an amount no less than 102% of their value. The Company does not record an asset or liability for the collateral as the Company is not permitted to sell or re-pledge the collateral. The collateral has at least the prevailing credit rating of United States Government Treasuries and Agencies. The Company utilizes a third party custodian to manage the exchange of funds and ensure that collateral received is maintained at 102% of the value of the reverse repurchase agreements on a daily basis.

Impairment of Long-Lived Assets

The Company continually evaluates whether events or circumstances have occurred that indicate that the estimated remaining useful life of its long-lived assets may warrant revision or that the carrying value of these assets may be impaired. The Company has not recognized any significant impairment charges from inception through December 31, 2020. 

Research and Development Expenses

Research and development costs are expensed as incurred. Research and development costs include salaries and personnel-related costs, stock-based compensation, consulting fees, fees paid for contract research services, the costs of laboratory equipment and facilities and other external costs. Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are deferred. The deferred amounts are expensed as the related goods are delivered or the services are performed. 

Stock-Based Compensation

The Company accounts for its stock-based compensation awards in accordance with Accounting Standards Codification (“ASC”) Topic 718, Compensation—Stock Compensation (“ASC 718”). ASC 718 requires all share-based payments to employees, including grants of employee stock options, to be recognized in the statements of operations based on their grant date fair values. For granted stock options, the Company estimates the grant date fair value of each option award using the Black-Scholes option-pricing model.  The use of the Black-Scholes option-pricing model requires management to make assumptions with respect to the expected term of the option, the expected volatility of the Company's common stock consistent with the expected term of the option, risk-free interest rates and expected dividend yields of the Company's common stock.  

For awards subject to service-based vesting conditions, the Company recognizes stock-based compensation expense equal to the grant date fair value of stock options on a straight-line basis over the requisite service period.

The Company expenses restricted stock awards based on the fair value of the award on a straight-line basis over the associated service period of the award.

During the years ended December 31, 2020 and 2019, the Company recorded stock-based compensation expense for employee and non-employee stock options and restricted stock, which was allocated as follows in the statements of operations (in thousands):

	Year Ended December 31,
	2020		2019
Research and development	$	599	$	616
General and administrative		790		896
Total	$	1,389	$	1,512

No related tax benefits were recognized for the years ended December 31, 2020 and 2019.

Net Loss Per Share

Basic net loss per share is calculated by dividing net loss by the weighted average shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is calculated by adjusting weighted average shares outstanding for the dilutive effect of common stock equivalents outstanding for the period, determined using the treasury-stock method. For purposes of the Company’s dilutive net loss per share calculation, stock options and warrants to purchase the Company's common stock were considered to be common stock equivalents but were excluded from the calculation of diluted net loss per share, as their effect would be anti-dilutive; therefore, basic and diluted net loss per share were the same for all periods presented.

The following common stock equivalents were excluded from the calculation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect:

	Year Ended December 31,
	2020	2019
Stock options	1,367,667	785,832
Common stock warrants	6,193,749	6,193,749
	7,561,416	6,979,581

Income Taxes

The Company provides deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the Company's financial statement carrying amounts and the tax basis of assets and liabilities using enacted tax rates expected to be in effect in the years in which the differences are expected to reverse. A valuation allowance is provided to reduce the deferred tax assets to the amount that will more likely than not be realized.

The Company accounts for uncertain tax positions in accordance with the provisions of ASC Topic 740, Expenses—Income Taxes. When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that the benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position as well as consideration of the available facts and circumstances. The Company did not have any significant uncertain tax positions for any periods presented.

Segment Information

Operating segments are identified as components of an enterprise for which separate discrete financial information is available for evaluation by the chief operating decision maker, the Company's chief executive officer, in making decisions on how to allocate resources and assess performance. The Company views its operations and manages its business in one operating segment. The Company operates in one geographic segment.

Comprehensive Loss

Comprehensive loss is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. For the year ended December 31, 2019 the amount in accumulated other comprehensive loss were comprised of unrealized gains and losses on short-term investments.

Leases

Effective January 1, 2019, the Company determines if an arrangement is a lease at inception. Operating leases are included in right-of-use (“ROU”) lease assets, current portion of lease obligations, and long-term lease obligations on the Company’s balance sheets. The Company does not currently hold any financing leases.

ROU lease assets represent the Company’s right to use an underlying asset for the lease term and lease obligations represent the Company’s obligation to make lease payments arising from the lease. Operating ROU lease assets and obligations are recognized at the commencement date based on the present value of lease payments over the lease term. As the Company’s facility leases do not provide an implicit rate, the Company uses its estimated incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The Company’s ROU lease assets also include any lease payments made and excludes lease incentives. If the Company’s facility lease includes options to terminate the lease which would affect the lease period when it is reasonably certain that the Company will exercise that option. Lease expense for lease payments under facility leases are recognized on a straight-line basis over the lease term.

Recent Accounting Pronouncements - Adopted

In August 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) 2018-13, Fair Value Measurement (Topic 820).  This standard includes amendments regarding changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and disclosure requirements of measurement uncertainty. This amendment was effective for annual reporting periods beginning after December 15, 2019.  Adoption of the standard did not have a material impact on the Company’s consolidated financial statements.

Recent Accounting Pronouncements - Not Yet Adopted

From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its financial position or results of operations upon adoption.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326). This standard requires a financial asset to be presented at amortized cost basis at the net amount expected to be collected. It also requires that credit losses relating to available-for-sale debt securities should be recorded through an allowance for credit losses. In November 2019, the FASB issued an amendment making this ASU effective for annual reporting periods beginning after December 15, 2022 for smaller reporting companies. Early adoption is permitted. The Company is currently evaluating the impact that this standard will have on its consolidated financial statements as well as the timing of when this standard will be adopted.

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Financial Instruments

12 Months Ended

Dec. 31, 2020

Financial Instruments

Financial Instruments

3.    Financial Instruments

The following tables present information about the Company’s financial assets and liabilities that have been measured at fair value, and indicates the fair value hierarchy of the valuation inputs utilized to determine such fair value. Below is a summary of assets and liabilities measured at fair value on a recurring basis (in thousands):

	As of December 31, 2020
	Quoted Prices		Significant		Significant
	in Active		Observable		Unobservable
	Markets		Inputs		Inputs
	(Level 1)		(Level 2)		(Level 3)		Total
Assets:
Cash and cash equivalents:
Money market funds	$	22,999	$	—	$	—	$	22,999
Short-term investments:
Reverse repurchase agreements		—		20,000		—		20,000
Total assets	$	22,999	$	20,000	$	—	$	42,999

	As of December 31, 2019
	Quoted Prices		Significant		Significant
	in Active		Observable		Unobservable
	Markets		Inputs		Inputs
	(Level 1)		(Level 2)		(Level 3)		Total
Assets:
Cash and cash equivalents:
Money market funds	$	5,432	$	—	$	—	$	5,432
Corporate debt securities		—		1,937		—		1,937
Short-term investments:
Commercial paper		—		1,993		—		1,993
Corporate debt securities		—		3,352		—		3,352
Reverse repurchase agreements		—		21,000		—		21,000
Total assets	$	5,432	$	28,282	$	—	$	33,714

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Short-Term Investments

12 Months Ended

Dec. 31, 2020

Short-Term Investments

Short-Term Investments

4.    Short-Term Investments

The following table summarizes the short-term investments held at December 31, 2020 and 2019 (in thousands):

			Gross Unrealized		Gross Unrealized
	Amortized Cost		Gains		Losses		Fair Value
December 31, 2020
Reverse repurchase agreements	$	20,000	$	—	$	—	$	20,000
Total	$	20,000	$	—	$	—	$	20,000

			Gross Unrealized		Gross Unrealized
	Amortized Cost		Gains		Losses		Fair Value
December 31, 2019
Commercial paper	$	1,993	$	—	$	—	$	1,993
Corporate debt securities		3,352		—		—		3,352
Reverse repurchase agreements		21,000		—		—		21,000
Total	$	26,345	$	—	$	—	$	26,345

The contractual maturities of all short-term investments held at December 31, 2020 and 2019 were one year or less. There were no short-term investments in an unrealized loss position at December 31, 2020. There were four short-term investments in an unrealized loss position at December 31, 2019,  none of which had been in an unrealized loss position for more than 12 months. The aggregate fair value of these securities at December 31, 2019 was approximately $3.4 million. The Company did not hold any securities with other-than-temporary impairments at December 31, 2020 and 2019.

Gross realized gains and losses on the sales of short-term investments are included in other income, net. Unrealized holding gains or losses for the period that have been included in accumulated other comprehensive income, as well as gains and losses reclassified out of accumulated other comprehensive income into other income, net were not material to the Company’s consolidated results of operations. During the years ended December 31, 2020 and 2019 all proceeds included in the Company's cash flows related to maturities of underlying securities. The gains on proceeds of maturities of short-term investments were not material to the Company’s consolidated results of operations for the years ended December 31, 2020 and 2019.

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Accrued Expenses

12 Months Ended

Dec. 31, 2020

Accrued Expenses

Accrued Expenses

5.    Accrued Expenses

Accrued expenses consisted of the following (in thousands):

	December 31,		December 31,
	2020		2019
Accrued contracted research costs	$	1,726	$	737
Accrued compensation		1,719		1,365
Accrued severance		396		—
Accrued professional fees		356		370
Accrued other		—		138
Total	$	4,197	$	2,610

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Commitments

12 Months Ended

Dec. 31, 2020

Commitments

Commitments

6.    Commitments

In November 2019, the Company entered into a sublease for office space which was classified as an operating lease. At inception of the lease, the Company recognized a lease liability and right-of-use asset of approximately $1.7 million. The lease liability represents the present value of the remaining lease payments, discounted using the Company’s estimated incremental borrowing rate of 7.49%. The ROU asset represents the lease liability adjusted for any prepaid and accrued rent payments.

Future minimum payments required under the non-cancelable operating leases as of December 31, 2020 are summarized as follows (in thousands):

Period Ending December 31,	Amount
2021		678
2022		438
Total lease payments	$	1,116
Less: imputed interest		(70)
Total operating lease liabilities	$	1,046

Rent expense was $0.8 million and $0.4 million for the years ended December 31, 2020 and 2019, respectively. Lease payments were $1.5 million and $1.4 million for the years ended December 31, 2020 and 2019, respectively.

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Stockholders' Equity

12 Months Ended

Dec. 31, 2020

Stockholders' Equity

Stockholders' Equity

7.   Stockholders’ Equity

Preferred Stock

As of December 31, 2020, the Company had 5,000,000 shares of preferred stock authorized for issuance, $0.001 par value per share, with none issued or outstanding.  Preferred stock may be issued from time to time in one or more series, each series to have such terms as stated or expressed in the resolutions providing for the issue of such series adopted by the board of directors of the Company. Preferred stock which may be redeemed, purchased or acquired by the Company may be reissued except as otherwise provided by law.

Common Stock Warrants

February 2019 Warrants

In the February 2019 Financing, the Company issued warrants to purchase 2,000,000 shares of common stock with an exercise price of $6.25 per share, which were immediately exercisable upon issuance and expire in February 2024.

The terms of the warrants include certain provisions related to fundamental transactions, a cashless exercise provision in the event registered shares are not available, and do not include any mandatory redemption provisions.  Therefore, the warrants have been classified in stockholders’ equity. Any changes to the fair value of the warrants will not be recognized so long as the warrants continue to be equity classified.

As of December 31, 2020, warrants to purchase 1,991,300 shares that were issued in the February 2019 Financing were outstanding with a remaining contractual life of 3.1 years.

June 2018 Warrants

On June 19, 2018, the Company entered into an underwriting agreement with Oppenheimer & Co. Inc. relating to an underwritten public offering of 4,200,000 shares of the Company's common stock, par value $0.001 per share, and accompanying warrants to purchase up to 4,200,000 shares of common stock. The warrants have an exercise price of $12.00 per share, were immediately exercisable upon issuance and expire in June 2023.

The terms of the warrants include certain provisions related to fundamental transactions, a cashless exercise provision in the event registered shares are not available and do not include any mandatory redemption provisions.  Therefore, the warrants have been classified in stockholders’ equity.  Any changes to fair value of the warrants will not be recognized so long as the warrants continue to be equity classified.

As of December 31, 2020, all warrants related to this transaction were outstanding with a remaining contractual life of 2.5 years.

Common Stock

As of December 31, 2020, the Company had 150,000,000 shares of common stock authorized for issuance, $0.001 par value per share, with 20,084,337 shares issued and outstanding.  The voting, dividend and liquidation rights of holders of common stock are subject to and qualified by the rights, powers and preferences of the holders of any outstanding preferred stock.

Reserved for Future Issuance

The Company has reserved for future issuance the following shares of common stock:

	December 31,	December 31,
	2020	2019
Warrants for the purchase of common stock	6,193,749	6,193,749
Options outstanding to purchase common stock	1,367,667	785,832
Options available for future issuance to purchase common stock	1,936,173	525,484
Shares reserved for the employee stock purchase plan	148,951	112,481
Total	9,646,540	7,617,546

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Stock Incentive Plans

12 Months Ended

Dec. 31, 2020

Stock Incentive Plans

Stock Incentive Plans

8. Stock Incentive Plans

Prior to the Company’s initial public offering in June 2015 (the “IPO”), the Company granted awards to eligible participants under its 2008 Equity Incentive Plan. In May 2015, the Company’s board of directors adopted and, in June 2015, the Company’s stockholders approved the 2015 Stock Incentive Plan (“2015 Plan”), which became effective immediately prior to the effectiveness of the IPO. Subsequent to the IPO, option grants are awarded to eligible participants only under the 2015 Plan.

The 2015 Plan provides for the grant of incentive stock options, non-statutory stock options, restricted stock awards, restricted stock units, stock appreciation rights and other stock-based awards. The Company’s employees, officers, directors and consultants and advisors are eligible to receive awards under the 2015 Plan.

Terms of stock option agreements, including vesting requirements, are determined by the Company's board of directors, subject to the provisions of the applicable stock incentive plan. Options granted by the Company generally vest ratably over four years, with a one-year cliff, and options are exercisable from the date of grant for a period of ten years. For options granted through December 31, 2020, the exercise price or purchase price, as applicable, equaled the estimated fair value of the common stock as determined by the Company's board of directors on the date of grant.

A summary of the Company’s stock option activity and related information for employees and non-employees follows:

				Weighted
				Average
		Weighted-		Remaining	Aggregate
		Average Exercise		Contractual	Intrinsic Value
	Shares	Price		Term (years)	(in thousands)
Outstanding at December 31, 2019	785,832	$	16.48	8.13	$	470
Granted	666,200	$	5.69
Exercised	(7,000)	$	4.39
Cancelled or forfeited	(76,884)	$	14.65
Expired	(481)	$	32.10
Outstanding at December 31, 2020	1,367,667	$	11.38	8.13	$	—
Vested and exercisable at December 31, 2020	504,171	$	21.22	6.68	$	—

The total intrinsic value of options exercised in the year ended December 31, 2020 was $29 thousand. There were no options exercised in the year ended December 31, 2019. The weighted-average grant date fair value of options granted to employees and non-employees for the years ended December 31, 2020 and 2019 was $3.81 and $3.25, respectively.

At December 31, 2020, the total unrecognized compensation expense related to unvested stock option awards was $2.7 million. The Company expects to recognize that cost over a weighted-average period of approximately 2.7 years.

Stock-Based Compensation Expense

The fair value of stock options granted to employees and non-employees was estimated using the Black-Scholes option-pricing model based on the following assumptions:

	Year Ended December 31,
	2020				2019
Weighted-average expected volatility	75.51	-	82.08	%	68.9	-	110.5	%
Expected term (in years)	5.50	-	6.25		5.50	-	10.00
Risk-free interest rate	0.37	-	1.51	%	1.39	-	2.69	%
Expected dividend yield			0	%			0	%

Volatility

Due to the lack of company-specific historical and implied volatility data of its common stock, the Company does not have relevant historical data to support its expected volatility. As such, the Company has used a weighted average of expected volatility based on the volatilities of a representative group of publicly traded biopharmaceutical companies. For purposes of identifying representative companies, the Company considered characteristics such as number of product candidates in early stages of product development, area of therapeutic focus, and length of trading history. The expected volatility was determined using an average of the historical volatilities of the representative group of companies for a period equal to the expected term of the option grant. The Company intends to continue to consistently apply this process using the same representative companies until a sufficient amount of historical information regarding the volatility of the Company's own share price becomes available or until circumstances change, such that the identified entities are no longer representative companies. In the latter case, more suitable, similar entities whose share prices are publicly available would be utilized in the calculation.

Expected Term

The Company uses the “simplified method” to estimate the expected term of stock option grants. Under this approach, the weighted-average expected life is presumed to be the average of the contractual term (ten years) and the vesting term (generally four years) of the Company's stock options, taking into consideration multiple vesting tranches. The Company utilizes this method due to lack of historical exercise data and the plain-vanilla nature of the Company's share-based awards.

Risk-Free Rate

The risk-free rate was based on the yield curve of United States Treasury securities with periods commensurate with the expected term of the options being valued.

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Income Taxes

12 Months Ended

Dec. 31, 2020

Income Taxes

Income Taxes

9.    Income Taxes

For the years ended December 31, 2020 and 2019, the Company did not record a provision for federal or state income taxes as it has incurred cumulative net operating losses since inception.

A reconciliation of the U.S. statutory income tax rate to the Company's effective tax rate is as follows for the years ended December 31, 2020 and 2019:

	Year Ended December 31,
	2020		2019
Federal income tax (benefit) at statutory rate	21.00	%	21.00	%
Permanent differences	(0.41)		(0.57)
Federal research and development credits and adjustments	2.78		2.42
State income tax, net of federal benefit	6.03		5.50
Other	0.37		0.49
Change in valuation allowance	(29.77)		(28.85)
Effective income tax rate	—	%	—	%

The Company's deferred tax assets consisted of the following (in thousands):

	Year Ended December 31,
	2020		2019
Deferred tax assets
Net operating loss carryforwards	$	65,373	$	55,283
Tax credit carryforwards		9,273		8,030
Capitalized research and development		482		922
Capitalized legal expenses		1,070		1,073
Lease liability		284		639
Other differences		1,648		1,453
Total deferred tax assets		78,130		67,400
Deferred tax liabilities
ROU asset		(262)		(639)
Valuation allowance		(77,868)		(66,761)
Net deferred tax assets	$	—	$	—

The Company recorded an increase to the valuation allowance of $11.1 million during the year ended December 31, 2020 due primarily to the federal and state net operating losses and tax credits generated. The Company recorded an increase to the valuation allowance of $7.6 million during the year ended December 31, 2019 which was also  primarily due to the federal and state net operating losses and tax credits generated.

In assessing the realizability of deferred tax assets, the Company considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which the temporary differences representing net future deductible amounts become deductible. Due to the Company's history of losses and expectation of future losses, the deferred tax assets were fully offset by a valuation allowance at December 31, 2020 and 2019.

As of December 31, 2020, the Company had approximately $240.1 million of federal and $236.7 million of state net operating loss respectively, which may be available to offset future taxable income. Federal net operating loss carryforwards of $150.5 million and state net operating loss carryforwards of $236.7 million will expire at various dates from 2023 through 2040. Federal net operating loss carryforwards of $89.6 can be carried forward indefinitely. The Company had approximately $7.4 million of federal and $2.4 million of state tax credit carryforwards available to reduce future tax liabilities as of December 31, 2020, which will expire at varying times through the year 2040.

The Internal Revenue Code of 1986, as amended (the “Code”), provides for a limitation of the annual use of net operating losses and other tax attributes (such as research and development tax credit carryforwards) following certain ownership changes (as defined by the Code) that could limit the Company's ability to utilize these carryforwards. At this time, the Company has not completed a study to assess whether an ownership change under Section 382 of the Code has occurred, or whether there have been multiple ownership changes since the Company's formation, due to the costs and complexities associated with such a study. The Company may have experienced various ownership changes, as defined by the Code, as a result of past financing transactions. Accordingly, the Company's ability to utilize the aforementioned carryforwards may be limited. Additionally, U.S. tax laws limit the time during which these carryforwards may be applied against future taxes. Therefore, the Company may not be able to take full advantage of these carryforwards for federal or state income tax purposes.

On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security (CARES) Act was signed into law making several changes to the Internal Revenue Code. The changes include, but are not limited to: increasing the limitation on the amount of deductible interest expense, allowing companies to carryback certain net operating losses, and increasing the amount of net operating loss carryforwards that corporations can use to offset taxable income. The tax law changes in the Act did not have a material impact on the Company's income tax provision.

As of December 31, 2020 and 2019, the Company did not have any significant unrecognized tax benefits. The Company had not accrued interest or penalties related to uncertain tax positions.

The federal and state income tax returns are generally subject to tax examinations for the tax years ended December 31, 2017 through December 31, 2020. To the extent the Company has tax attribute carryforwards, the tax years in which the attribute was generated may still be adjusted upon examination by the Internal Revenue Service or state taxing authorities to the extent utilized in a future period.

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Defined Contribution Benefit Plan

12 Months Ended

Dec. 31, 2020

Defined Contribution Benefit Plan

Defined Contribution Benefit Plan

10.   Defined Contribution Benefit Plan

The Company sponsors a 401(k) retirement plan, in which substantially all of its employees are eligible to participate. Participants may contribute a percentage of their annual compensation to this plan, subject to statutory limitations. The Company did not provide any contributions to this plan during the years ended December 31, 2020 or 2018.

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Subsequent Events

12 Months Ended

Dec. 31, 2020

Subsequent Events

Subsequent Events

11.   Subsequent Events

Agreement and Plan of Merger

On January 28, 2021, the Company acquired Quellis. Under the terms of the Merger Agreement, the Company issued to the stockholders of Quellis 3,332,669 shares of the Company’s common stock, par value $0.001 per share, and 50,504 shares of newly designated Series X Preferred Stock (as described below) which had a conversion value on the closing date of $122.7 million. In addition, the Company assumed options granted under the Quellis stock option plan, a warrant to purchase 2,805 shares of Series X Preferred Stock at an exercise price of $341.70 per share, and a warrant to purchase 185,136 shares of the Company’s common stock at an exercise price of $0.35 per share, which warrants are exercisable until December 14, 2030.

Stock Purchase Agreement

On January 28, 2021, the Company entered into a Stock Purchase Agreement (the “Purchase Agreement”) with certain institutional and accredited investors (the “Investors”). Pursuant to the Purchase Agreement, the Company agreed to sell an aggregate of 35,573 shares of Series X Preferred Stock for gross proceeds of approximately $110.0 million (the “February 2021 Financing”).

Series X Preferred Stock

As a result of the above transactions, in 2021 the Company issued the following Series X Preferred Stock or warrants to purchase Series X Preferred Stock:

	Series X	Common Stock
	Preferred	Issuable Upon
	Shares	Conversion (1)
Outstanding shares issued in merger	50,504	50,504,000
Outstanding shares issued in February 2021 Financing	35,573	35,573,000
Warrants assumed in merger	2,805	2,805,000
Total	88,882	88,882,000

(1) Requires stockholder approval for conversion.

Subject to stockholder approval, each share of Series X Preferred Stock is convertible into 1,000 shares of common stock.

The Company is required to hold a stockholders’ meeting to submit the following matters to its stockholders for their consideration: (i) the approval of the conversion of the Series X Preferred Stock into shares of the Company’s common stock in accordance with Nasdaq Listing Rule 5635(a) (the “Conversion Proposal”) and (ii) if necessary or appropriate, the approval of an amendment to the certificate of incorporation of the Company to authorize sufficient shares of common stock for the conversion of the Series X Preferred Stock issued pursuant to the Merger Agreement and the Purchase Agreement (as described above) and/or to effectuate a reverse stock split the “Charter Amendment Proposal.”  

If the Company’s stockholders do not approve the conversion of the Series X Preferred Stock by July 28, 2021, then the holders of the Series X Preferred Stock are entitled to require the Company to make redemption payments at a price per share equal to the fair value of undelivered shares of common stock, defined as the last reported closing price of the Company’s common stock on the trading day on which notice of conversion is delivered to the Company. Using the closing price on March 4, 2021 of $2.87, if all currently outstanding Series X Preferred Stock was redeemed for cash, the Company would be required to make a payment of $247.0 million. The Company has insufficient liquidity to make such a payment, if required.

Holders of Series X Preferred Stock are entitled to receive dividends on shares of Series X Preferred Stock equal, on an as-if-converted-to-common-stock basis, and in the same form as dividends actually paid on shares of the Company’s common stock. Except as otherwise required by law, the Series X Preferred Stock does not have voting rights. However, as long as any shares of Series X Preferred Stock are outstanding, the Company may not, without the affirmative vote of the holders of a majority of the then outstanding shares of the Series X Preferred Stock, (i) alter or change adversely the powers, preferences or rights given to the Series X Preferred Stock or alter or amend the Certificate of Designation that authorized the Series X Preferred Stock, amend or repeal any provision of, or add any provision to, the Company’s Certificate of Incorporation or bylaws, or file any articles of amendment, certificate of designations, preferences, limitations and relative rights of any series of preferred stock, if such action would adversely alter or change the preferences, rights, privileges or powers of, or restrictions provided for the benefit of the Series X Preferred Stock, (ii) issue further shares of Series X Preferred Stock or increase or decrease (other than by conversion) the number of authorized shares of Series X Preferred Stock, or (iii) enter into any agreement with respect to any of the foregoing. Additionally, the approval of the holders of a majority of the Series X Preferred Stock is required for certain change of control transactions, provided that this approval right will terminate upon stockholder approval of the Conversion Proposal.

Following stockholder approval of the Conversion Proposal, on the fourth business day after the date on which such stockholder approval is received, each share of Series X Preferred Stock then outstanding automatically converts into 1,000 shares of the Company’s common stock, subject to certain beneficial ownership limitations, including that a holder of Series X Preferred Stock is prohibited from converting shares of Series X Preferred Stock into shares of the Company’s common stock if, as a result of such conversion, such holder, together with its affiliates, would beneficially own more than a specified percentage (to be initially set at 9.99% and thereafter adjustable by the holder to a number between 4.99% and 19.99%) of the total number of shares of the Company’s common stock issued and outstanding immediately after giving effect to such conversion.  Shares of Series X Preferred Stock not converted automatically are thereafter subject to conversion at the option of the holder.

Registration Rights Agreement

On January 28, 2021, the Company entered into a Registration Rights Agreement (the “Registration Rights Agreement”) with the Investors. Pursuant to the Registration Rights Agreement, the Company agreed to prepare and file a resale registration statement with the SEC within 90 calendar days following the closing of the February 2021 Financing (the “Filing Deadline”). The Company agreed to use its reasonable best efforts to cause this registration statement to be declared effective by the SEC within 30 calendar days of the Filing Deadline (or within 60 calendar days if the SEC reviews the registration statement).

The Company also agreed, among other things, to indemnify the Investors, their officers, directors, members, employees and agents, successors and assigns under the registration statement from certain liabilities and pay all fees and expenses (excluding any legal fees of the selling holder(s), and any underwriting discounts and selling commissions) incident to the Company’s obligations under the Registration Rights Agreement.

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Summary of Significant Accounting Polices (Polices)

12 Months Ended

Dec. 31, 2020

Summary of Significant Accounting Policies

Basis of Presentation and Principles of Consolidation

Basis of Presentation and Principles of Consolidation

The accompanying consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary, Catabasis Securities Corporation.  All intercompany balances and transactions have been eliminated in consolidation. These consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”) and include all adjustments necessary for the fair presentation of the Company’s financial position for the periods presented.  

Use of Estimates

Use of Estimates 

The preparation of the Company’s consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from such estimates.

The Company utilizes certain estimates to record expenses relating to research and development contracts. These contract estimates, which are primarily related to the length of service of each contract and the amount of service provided as of each measurement date, are determined by the Company based on input from internal project management, as well as from third-party service providers.

Off-Balance Sheet Risk and Concentrations of Credit Risk

Off-Balance Sheet Risk and Concentrations of Credit Risk

The Company has no off-balance sheet risk, such as foreign exchange contracts, option contracts or other foreign hedging arrangements. Financial instruments that subject the Company to credit risk primarily consist of cash, cash equivalents, short-term investments and restricted cash. The primary objectives for the Company's investment portfolio are the preservation of capital and the maintenance of liquidity. The Company's investment policy includes guidelines on the quality of the institutions and financial instruments and defines allowable investments that the Company believes minimizes the exposure to concentration of credit risk. 

Cash and Cash Equivalents and Restricted Cash

Cash and Cash Equivalents and Restricted Cash

The Company considers highly liquid investments with a maturity of three months or less or reverse repurchase agreements with a maturity period of one business day or less when purchased to be cash equivalents. Cash equivalents, which consist of money market funds, corporate debt securities and reverse repurchase agreements are stated at fair value. Cash and cash equivalents consist of the following (in thousands):

	December 31,
	2020		2019
Cash	$	1,931	$	2,530
Money market fund		22,999		5,432
Corporate debt securities		—		1,937
Total	$	24,930	$	9,899

The reconciliation of cash, cash equivalents and restricted cash reported within the applicable balance sheet that sum to the total of the same such amount shown in the statement of cash flows is as follows (in thousands):

	December 31,
	2020		2019
Cash and cash equivalents	$	24,930	$	9,899
Restricted cash (1)		121		477
Total	$	25,051	$	10,376

(1) Included in prepaid expenses and other current assets and other assets.

Short-Term Investments

Short-Term Investments

The Company classifies all corporate debt securities with a remaining maturity of greater than three months and reverse repurchase agreements with a remaining maturity of greater than one business day at the time of purchase as short-term investments. Short-term investments are recorded at fair value, with the unrealized gains and losses reported in other comprehensive loss. The amortized cost of debt securities is adjusted for the amortization of premiums and accretion of discounts to maturity. Such amortization is included in interest and investment income. Realized gains and losses, interest, dividends and declines in value judged to be other-than-temporary are included in interest and investment income.

The cost of securities sold is based on the specific identification method for purposes of recording realized gains and losses. To determine whether an other-than-temporary impairment exists, the Company considers whether it has the ability and intent to hold the investment until a market price recovery, and whether evidence indicating the recoverability of the cost of the investment outweighs evidence to the contrary.

Fair Value of Financial Instruments

Fair Value of Financial Instruments

The fair value hierarchy prioritizes the inputs to valuation techniques used to measure fair value into three broad levels as follows: Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities; Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly; and Level 3 inputs are unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability. Financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement.

The carrying amounts reflected in the balance sheets for cash equivalents, restricted cash, prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair values at December 31, 2020 and 2019, due to their short-term nature. There have been no changes to the valuation methods during the years ended December 31, 2020 and 2019. The Company evaluates transfers between levels at the end of each reporting period. There were no transfers of assets or liabilities between levels during the year ended December 31, 2020 and 2019.

The Company’s investment portfolio may include fixed income securities that do not always trade on a daily basis. As a result, the pricing services used by the Company apply other available information as applicable through processes such as benchmark yields, benchmarking of like securities, sector groupings and matrix pricing to prepare valuations. The Company validates the prices provided by its third party pricing services by obtaining market values from other pricing sources and analyzing pricing data in certain instances. The Company also invests in certain reverse repurchase agreements which are collateralized by deposits in the form of United States Government Securities and Obligations for an amount no less than 102% of their value. The Company does not record an asset or liability for the collateral as the Company is not permitted to sell or re-pledge the collateral. The collateral has at least the prevailing credit rating of United States Government Treasuries and Agencies. The Company utilizes a third party custodian to manage the exchange of funds and ensure that collateral received is maintained at 102% of the value of the reverse repurchase agreements on a daily basis.

Impairment of Long-Lived Assets

Impairment of Long-Lived Assets

The Company continually evaluates whether events or circumstances have occurred that indicate that the estimated remaining useful life of its long-lived assets may warrant revision or that the carrying value of these assets may be impaired. The Company has not recognized any significant impairment charges from inception through December 31, 2020. 

Research and Development Expenses

Research and Development Expenses

Research and development costs are expensed as incurred. Research and development costs include salaries and personnel-related costs, stock-based compensation, consulting fees, fees paid for contract research services, the costs of laboratory equipment and facilities and other external costs. Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are deferred. The deferred amounts are expensed as the related goods are delivered or the services are performed. 

Stock-Based Compensation

Stock-Based Compensation

The Company accounts for its stock-based compensation awards in accordance with Accounting Standards Codification (“ASC”) Topic 718, Compensation—Stock Compensation (“ASC 718”). ASC 718 requires all share-based payments to employees, including grants of employee stock options, to be recognized in the statements of operations based on their grant date fair values. For granted stock options, the Company estimates the grant date fair value of each option award using the Black-Scholes option-pricing model.  The use of the Black-Scholes option-pricing model requires management to make assumptions with respect to the expected term of the option, the expected volatility of the Company's common stock consistent with the expected term of the option, risk-free interest rates and expected dividend yields of the Company's common stock.  

For awards subject to service-based vesting conditions, the Company recognizes stock-based compensation expense equal to the grant date fair value of stock options on a straight-line basis over the requisite service period.

The Company expenses restricted stock awards based on the fair value of the award on a straight-line basis over the associated service period of the award.

During the years ended December 31, 2020 and 2019, the Company recorded stock-based compensation expense for employee and non-employee stock options and restricted stock, which was allocated as follows in the statements of operations (in thousands):

	Year Ended December 31,
	2020		2019
Research and development	$	599	$	616
General and administrative		790		896
Total	$	1,389	$	1,512

No related tax benefits were recognized for the years ended December 31, 2020 and 2019.

Net Loss Per Share

Net Loss Per Share

Basic net loss per share is calculated by dividing net loss by the weighted average shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is calculated by adjusting weighted average shares outstanding for the dilutive effect of common stock equivalents outstanding for the period, determined using the treasury-stock method. For purposes of the Company’s dilutive net loss per share calculation, stock options and warrants to purchase the Company's common stock were considered to be common stock equivalents but were excluded from the calculation of diluted net loss per share, as their effect would be anti-dilutive; therefore, basic and diluted net loss per share were the same for all periods presented.

The following common stock equivalents were excluded from the calculation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect:

	Year Ended December 31,
	2020	2019
Stock options	1,367,667	785,832
Common stock warrants	6,193,749	6,193,749
	7,561,416	6,979,581

Income Taxes

Income Taxes

The Company provides deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the Company's financial statement carrying amounts and the tax basis of assets and liabilities using enacted tax rates expected to be in effect in the years in which the differences are expected to reverse. A valuation allowance is provided to reduce the deferred tax assets to the amount that will more likely than not be realized.

The Company accounts for uncertain tax positions in accordance with the provisions of ASC Topic 740, Expenses—Income Taxes. When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that the benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position as well as consideration of the available facts and circumstances. The Company did not have any significant uncertain tax positions for any periods presented.

Segment Information

Segment Information

Operating segments are identified as components of an enterprise for which separate discrete financial information is available for evaluation by the chief operating decision maker, the Company's chief executive officer, in making decisions on how to allocate resources and assess performance. The Company views its operations and manages its business in one operating segment. The Company operates in one geographic segment.

Comprehensive Loss

Comprehensive Loss

Comprehensive loss is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. For the year ended December 31, 2019 the amount in accumulated other comprehensive loss were comprised of unrealized gains and losses on short-term investments.

Leases

Leases

Effective January 1, 2019, the Company determines if an arrangement is a lease at inception. Operating leases are included in right-of-use (“ROU”) lease assets, current portion of lease obligations, and long-term lease obligations on the Company’s balance sheets. The Company does not currently hold any financing leases.

ROU lease assets represent the Company’s right to use an underlying asset for the lease term and lease obligations represent the Company’s obligation to make lease payments arising from the lease. Operating ROU lease assets and obligations are recognized at the commencement date based on the present value of lease payments over the lease term. As the Company’s facility leases do not provide an implicit rate, the Company uses its estimated incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The Company’s ROU lease assets also include any lease payments made and excludes lease incentives. If the Company’s facility lease includes options to terminate the lease which would affect the lease period when it is reasonably certain that the Company will exercise that option. Lease expense for lease payments under facility leases are recognized on a straight-line basis over the lease term.

Recent Accounting Pronouncements - Adopted and not yet adopted

Recent Accounting Pronouncements - Adopted

In August 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) 2018-13, Fair Value Measurement (Topic 820).  This standard includes amendments regarding changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and disclosure requirements of measurement uncertainty. This amendment was effective for annual reporting periods beginning after December 15, 2019.  Adoption of the standard did not have a material impact on the Company’s consolidated financial statements.

Recent Accounting Pronouncements - Not Yet Adopted

From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its financial position or results of operations upon adoption.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326). This standard requires a financial asset to be presented at amortized cost basis at the net amount expected to be collected. It also requires that credit losses relating to available-for-sale debt securities should be recorded through an allowance for credit losses. In November 2019, the FASB issued an amendment making this ASU effective for annual reporting periods beginning after December 15, 2022 for smaller reporting companies. Early adoption is permitted. The Company is currently evaluating the impact that this standard will have on its consolidated financial statements as well as the timing of when this standard will be adopted.

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Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2020

Summary of Significant Accounting Policies

Schedule of cash and cash equivalents

Cash and cash equivalents consist of the following (in thousands):

	December 31,
	2020		2019
Cash	$	1,931	$	2,530
Money market fund		22,999		5,432
Corporate debt securities		—		1,937
Total	$	24,930	$	9,899

Schedule of reconciliation of cash, cash equivalents and restricted cash

The reconciliation of cash, cash equivalents and restricted cash reported within the applicable balance sheet that sum to the total of the same such amount shown in the statement of cash flows is as follows (in thousands):

	December 31,
	2020		2019
Cash and cash equivalents	$	24,930	$	9,899
Restricted cash (1)		121		477
Total	$	25,051	$	10,376

(1) Included in prepaid expenses and other current assets and other assets.

Schedule of stock-based compensation expense

During the years ended December 31, 2020 and 2019, the Company recorded stock-based compensation expense for employee and non-employee stock options and restricted stock, which was allocated as follows in the statements of operations (in thousands):

	Year Ended December 31,
	2020		2019
Research and development	$	599	$	616
General and administrative		790		896
Total	$	1,389	$	1,512

Schedule of anti-dilutive common stock equivalents excluded from calculation of diluted net loss per share

	Year Ended December 31,
	2020	2019
Stock options	1,367,667	785,832
Common stock warrants	6,193,749	6,193,749
	7,561,416	6,979,581

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Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2020

Financial Instruments

Schedule of assets measured fair value on recurring basis

Below is a summary of assets and liabilities measured at fair value on a recurring basis (in thousands):

	As of December 31, 2020
	Quoted Prices		Significant		Significant
	in Active		Observable		Unobservable
	Markets		Inputs		Inputs
	(Level 1)		(Level 2)		(Level 3)		Total
Assets:
Cash and cash equivalents:
Money market funds	$	22,999	$	—	$	—	$	22,999
Short-term investments:
Reverse repurchase agreements		—		20,000		—		20,000
Total assets	$	22,999	$	20,000	$	—	$	42,999

	As of December 31, 2019
	Quoted Prices		Significant		Significant
	in Active		Observable		Unobservable
	Markets		Inputs		Inputs
	(Level 1)		(Level 2)		(Level 3)		Total
Assets:
Cash and cash equivalents:
Money market funds	$	5,432	$	—	$	—	$	5,432
Corporate debt securities		—		1,937		—		1,937
Short-term investments:
Commercial paper		—		1,993		—		1,993
Corporate debt securities		—		3,352		—		3,352
Reverse repurchase agreements		—		21,000		—		21,000
Total assets	$	5,432	$	28,282	$	—	$	33,714

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Short-Term Investments (Tables)

12 Months Ended

Dec. 31, 2020

Short-Term Investments

Schedule of short term investments

The following table summarizes the short-term investments held at December 31, 2020 and 2019 (in thousands):

			Gross Unrealized		Gross Unrealized
	Amortized Cost		Gains		Losses		Fair Value
December 31, 2020
Reverse repurchase agreements	$	20,000	$	—	$	—	$	20,000
Total	$	20,000	$	—	$	—	$	20,000

			Gross Unrealized		Gross Unrealized
	Amortized Cost		Gains		Losses		Fair Value
December 31, 2019
Commercial paper	$	1,993	$	—	$	—	$	1,993
Corporate debt securities		3,352		—		—		3,352
Reverse repurchase agreements		21,000		—		—		21,000
Total	$	26,345	$	—	$	—	$	26,345

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Accrued Expenses (Tables)

12 Months Ended

Dec. 31, 2020

Accrued Expenses

Schedule of accrued expenses

Accrued expenses consisted of the following (in thousands):

	December 31,		December 31,
	2020		2019
Accrued contracted research costs	$	1,726	$	737
Accrued compensation		1,719		1,365
Accrued severance		396		—
Accrued professional fees		356		370
Accrued other		—		138
Total	$	4,197	$	2,610

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Commitments (Tables)

12 Months Ended

Dec. 31, 2020

Commitments

Schedule of future minimum payments required under the non-cancelable operating leases

Future minimum payments required under the non-cancelable operating leases as of December 31, 2020 are summarized as follows (in thousands):

Period Ending December 31,	Amount
2021		678
2022		438
Total lease payments	$	1,116
Less: imputed interest		(70)
Total operating lease liabilities	$	1,046

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Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2020

Stockholders' Equity

Schedule of common stock reserved for future issuance

	December 31,	December 31,
	2020	2019
Warrants for the purchase of common stock	6,193,749	6,193,749
Options outstanding to purchase common stock	1,367,667	785,832
Options available for future issuance to purchase common stock	1,936,173	525,484
Shares reserved for the employee stock purchase plan	148,951	112,481
Total	9,646,540	7,617,546

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Stock Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2020

Stock Incentive Plans

Summary of stock option activity

				Weighted
				Average
		Weighted-		Remaining	Aggregate
		Average Exercise		Contractual	Intrinsic Value
	Shares	Price		Term (years)	(in thousands)
Outstanding at December 31, 2019	785,832	$	16.48	8.13	$	470
Granted	666,200	$	5.69
Exercised	(7,000)	$	4.39
Cancelled or forfeited	(76,884)	$	14.65
Expired	(481)	$	32.10
Outstanding at December 31, 2020	1,367,667	$	11.38	8.13	$	—
Vested and exercisable at December 31, 2020	504,171	$	21.22	6.68	$	—

Schedule of assumptions made based on the Black-Scholes option pricing model

	Year Ended December 31,
	2020				2019
Weighted-average expected volatility	75.51	-	82.08	%	68.9	-	110.5	%
Expected term (in years)	5.50	-	6.25		5.50	-	10.00
Risk-free interest rate	0.37	-	1.51	%	1.39	-	2.69	%
Expected dividend yield			0	%			0	%

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Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Taxes

Schedule of reconciliation of U.S. statutory income tax rate to effective tax rate

	Year Ended December 31,
	2020		2019
Federal income tax (benefit) at statutory rate	21.00	%	21.00	%
Permanent differences	(0.41)		(0.57)
Federal research and development credits and adjustments	2.78		2.42
State income tax, net of federal benefit	6.03		5.50
Other	0.37		0.49
Change in valuation allowance	(29.77)		(28.85)
Effective income tax rate	—	%	—	%

Schedule of components of deferred tax assets

The Company's deferred tax assets consisted of the following (in thousands):

	Year Ended December 31,
	2020		2019
Deferred tax assets
Net operating loss carryforwards	$	65,373	$	55,283
Tax credit carryforwards		9,273		8,030
Capitalized research and development		482		922
Capitalized legal expenses		1,070		1,073
Lease liability		284		639
Other differences		1,648		1,453
Total deferred tax assets		78,130		67,400
Deferred tax liabilities
ROU asset		(262)		(639)
Valuation allowance		(77,868)		(66,761)
Net deferred tax assets	$	—	$	—

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Subsequent Events (Tables)

12 Months Ended

Dec. 31, 2020

Subsequent Events

Schedule of Series X preferred stock or warrants

	Series X	Common Stock
	Preferred	Issuable Upon
	Shares	Conversion (1)
Outstanding shares issued in merger	50,504	50,504,000
Outstanding shares issued in February 2021 Financing	35,573	35,573,000
Warrants assumed in merger	2,805	2,805,000
Total	88,882	88,882,000

(1) Requires stockholder approval for conversion.

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Organization and Operations (Details) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	Jan. 30, 2020	Feb. 06, 2019	Dec. 31, 2020	Dec. 31, 2019
Common Stock
Gross proceeds from public offering			$ 16,270	$ 6,996
Accumulated deficit			(260,897)	$ (223,597)
Cash, cash equivalents and short-term investments			44,900
Revenue			0
Net proceeds			$ 104,000
Series X Preferred Stock
Common Stock
Number of shares issued			86,077
Shares issued			86,077
Series X Common shares, As converted
Common Stock
Shares agreed to issue upon shareholders approval			86,077,000
Private Placement
Common Stock
Gross proceeds			$ 110,000
Common Stock
Common Stock
Number of shares issued			2,353,737	1,282,904
Gross proceeds from public offering			$ 3	$ 1
Shares issued			2,353,737	1,282,904
Common Stock | ATM
Common Stock
Number of shares issued			2,353,737
Share price (in dollars per share)			$ 7.13
Gross proceeds from public offering			$ 16,800
Proceeds from public offering, net of issuance costs			$ 16,300
Shares issued			2,353,737
Common Stock | Cowen
Common Stock
Percentage of commission paid to underwriter based on proceeds from common stock			3.00%
Remaining available under sales agreement			$ 27,900
Common Stock | Oppenheimer & Co. Inc | February 2019 Financing
Common Stock
Number of shares issued		4,000,000
Number of warrants issued		2,000,000
Warrants price (in dollars per unit)		$ 5.00
Proceeds from public offering, net of issuance costs		$ 18,500
Shares issued		4,000,000
Common Stock | Oppenheimer & Co. Inc | Over-Allotment option
Common Stock
Number of shares issued	20.0
Shares issued	20.0
Common Stock | Oppenheimer & Co. Inc | January 2020 Financing
Common Stock
Number of shares issued	5,290,000
Share price (in dollars per share)	$ 5.00
Gross proceeds from public offering	$ 26,500
Proceeds from public offering, net of issuance costs	$ 24,600
Shares issued	5,290,000

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Summary of Significant Accounting Polices - Cash and Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash and Cash Equivalents and Restricted Cash
Cash and cash equivalents	$ 24,930	$ 9,899
Restricted cash	121	477
Total	25,051	10,376	$ 15,407
Cash
Cash and Cash Equivalents and Restricted Cash
Cash and cash equivalents	1,931	2,530
Money market fund
Cash and Cash Equivalents and Restricted Cash
Cash and cash equivalents	$ 22,999	5,432
Corporate debt securities
Cash and Cash Equivalents and Restricted Cash
Cash and cash equivalents		$ 1,937

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Summary of Significant Accounting Polices - Fair Value of Financial Instruments (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Fair Value of Financial Instruments
Fair value assets, transfers from Level 1 to Level 2	$ 0
Fair value assets, transfers from Level 2 to Level 1	0
Fair value liabilities, transfers from Level 1 to Level 2	0
Fair value liabilities, transfers from Level 2 to Level 1	$ 0
Reverse repurchase agreements | Government Securities and Obligations | Minimum
Fair Value of Financial Instruments
Percentage of investment amount to collateralized deposits value	102.00%

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Summary of Significant Accounting Policies - Stock-Based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Stock-Based Compensation
Stock-based compensation expense	$ 1,389	$ 1,512
Tax benefits recognized from stock-based compensation expense	0	0
Research and development
Stock-Based Compensation
Stock-based compensation expense	599	616
General and administrative
Stock-Based Compensation
Stock-based compensation expense	$ 790	$ 896

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Summary of Significant Accounting Policies - Net Loss Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Antidilutive common stock equivalents excluded from computation of diluted net loss per share
Anti-dilutive securities excluded from the calculation of diluted net loss per share (in shares)	7,561,416	6,979,581
Stock options
Antidilutive common stock equivalents excluded from computation of diluted net loss per share
Anti-dilutive securities excluded from the calculation of diluted net loss per share (in shares)	1,367,667	785,832
Common stock warrants
Antidilutive common stock equivalents excluded from computation of diluted net loss per share
Anti-dilutive securities excluded from the calculation of diluted net loss per share (in shares)	6,193,749	6,193,749

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Summary of Significant Accounting Policies - Segment Information (Details)	12 Months Ended
	Dec. 31, 2020 segment
Summary of Significant Accounting Policies
Number of operating segments	1

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Financial Instruments (Details) - Recurring - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Summary of assets measured at fair value on a recurring basis
Total assets	$ 42,999	$ 33,714
Level 1
Summary of assets measured at fair value on a recurring basis
Total assets	22,999	5,432
Level 2
Summary of assets measured at fair value on a recurring basis
Total assets	20,000	28,282
Money market fund
Summary of assets measured at fair value on a recurring basis
Cash and cash equivalents	22,999	5,432
Money market fund | Level 1
Summary of assets measured at fair value on a recurring basis
Cash and cash equivalents	22,999	5,432
Commercial paper
Summary of assets measured at fair value on a recurring basis
Short-term investments		1,993
Commercial paper | Level 2
Summary of assets measured at fair value on a recurring basis
Short-term investments		1,993
Corporate debt securities
Summary of assets measured at fair value on a recurring basis
Cash and cash equivalents		1,937
Short-term investments		3,352
Corporate debt securities | Level 2
Summary of assets measured at fair value on a recurring basis
Cash and cash equivalents		1,937
Short-term investments		3,352
Reverse repurchase agreements
Summary of assets measured at fair value on a recurring basis
Short-term investments	20,000	21,000
Reverse repurchase agreements | Level 2
Summary of assets measured at fair value on a recurring basis
Short-term investments	$ 20,000	$ 21,000

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Short-Term Investments (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) instrument	Dec. 31, 2019 USD ($) instrument
Short-Term Investments
Amortized Cost	$ 20,000	$ 26,345
Fair Value	$ 20,000	$ 26,345
Number of short term investments in unrealized loss position | instrument	0	4
Number of short term investments in an unrealized loss position more than 12 months | instrument		0
Aggregate fair value of the investments in an unrealized loss position		$ 3,400
Commercial paper
Short-Term Investments
Amortized Cost		1,993
Fair Value		1,993
Corporate debt securities
Short-Term Investments
Amortized Cost		3,352
Fair Value		3,352
Reverse repurchase agreements
Short-Term Investments
Amortized Cost	$ 20,000	21,000
Fair Value	$ 20,000	$ 21,000

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Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accrued Expenses
Accrued contracted research costs	$ 1,726	$ 737
Accrued compensation	1,719	1,365
Accrued severance	396
Accrued professional fees	356	370
Accrued other		138
Total	$ 4,197	$ 2,610

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Commitments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Nov. 30, 2019
Sublease
Operating Lease, Right-of-Use Asset	$ 966	$ 2,349	$ 1,700
Operating Lease, Liability	1,046		$ 1,700
Operating Lease, Weighted Average Discount Rate, Percent			7.49%
Maturity analysis of undiscounted cash flows of operating lease liabilities
2021	678
2022	438
Total lease payments	1,116
Less: imputed interest	(70)
Total operating lease liabilities	1,046		$ 1,700
Rent expense	800	400
Lease payments	$ 1,500	$ 1,400

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Stockholders' Equity - Preferred Stock (Details)	Dec. 31, 2020 series $ / shares shares	Dec. 31, 2019 $ / shares shares
Preferred Stock
Preferred stock, authorized (in shares)	5,000,000	5,000,000
Preferred stock, par value (in dollars per share) | $ / shares	$ 0.001	$ 0.001
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Minimum number of series used to issue preferred stock | series	1

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Stockholders' Equity - Common Stock Warrants (Details) - Common stock warrants - $ / shares	12 Months Ended
	Dec. 31, 2020	Feb. 28, 2019	Jun. 30, 2018
February 2019 Financing
Common Stock Warrants
Number of shares which may be purchased with warrants		2,000,000
Exercise Price (in dollars per share)		$ 6.25
Warrants term		5 years
Number of warrants outstanding (in shares)	1,991,300
Remaining contractual term	3 years 1 month 6 days
June 2018 Financing
Common Stock Warrants
Number of shares which may be purchased with warrants			4,200,000
Exercise Price (in dollars per share)			$ 12.00
Warrants term			2023 years
Remaining contractual term	2 years 6 months

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Stockholders' Equity - Common Stock (Details) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Common Stock
Common stock, authorized (in shares)	150,000,000	150,000,000
Par value of common stock (in dollars per share)	$ 0.001	$ 0.001
Common stock, issued (in shares)	20,084,337	12,433,600
Common Stock, outstanding (in shares)	20,084,337	12,433,600

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Stockholders' Equity - Shares Reserved for Future Issuance (Details) - shares	Dec. 31, 2020	Dec. 31, 2019
Stockholders' Equity
Number of shares reserved for future issuance	9,646,540	7,617,546
Warrants for the purchase of Common Stock
Stockholders' Equity
Number of shares reserved for future issuance	6,193,749	6,193,749
Options outstanding to purchase Common Stock
Stockholders' Equity
Number of shares reserved for future issuance	1,367,667	785,832
Options available for future issuance to purchase Common Stock
Stockholders' Equity
Number of shares reserved for future issuance	1,936,173	525,484
Shares reserved for the employee stock purchase plan
Stockholders' Equity
Number of shares reserved for future issuance	148,951	112,481

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Stock Incentive Plans - Summary of Plans (Details) - Stock options	12 Months Ended
	Dec. 31, 2020
Stock Incentive Plans
Vesting period	4 years
Cliff period for vesting	1 year
Expiration period	10 years

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Stock Incentive Plans - Stock option activity (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Shares
Outstanding, beginning of period (in shares)	785,832	785,832
Granted (in shares)		666,200
Exercised (in shares)		(7,000)
Cancelled or forfeited (in shares)		(76,884)
Expired (in shares)		(481)
Outstanding, end of period (in shares)		1,367,667	785,832
Vested and exercisable (in shares)		504,171
Weighted-Average Exercise Price
Outstanding, beginning of period (in dollars per share)	$ 16.48	$ 16.48
Granted (in dollars per share)		5.69
Exercised (in dollars per share)		4.39
Cancelled or forfeited (in dollars per share)		14.65
Expired (in dollars per share)		32.10
Outstanding at end of year (in dollars per share)		11.38	$ 16.48
Vested and Exercisable (in dollars per share)		$ 21.22
Weighted Average Remaining Contractual Term (years)
Outstanding	8 years 1 month 17 days		8 years 1 month 17 days
Vested and Exercisable	6 years 8 months 5 days
Aggregate Intrinsic Value
Outstanding			$ 470
Stock options
Shares
Exercised (in shares)			0
Additional disclosures
Intrinsic value of options exercised		$ 29
Weighted average grant date fair value of options granted (in dollars per share)		$ 3.81	$ 3.25
Unrecognized compensation expense related to unvested stock option awards		$ 2,700
Weighted-average amortization period over which cost is expected to be recognized		2 years 8 months 12 days

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Stock Incentive Plans - Stock-Based Compensation Expense (Details) - Stock options	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Assumptions used to calculate fair value of stock options
Expected dividend yield	0.00%	0.00%
Minimum
Assumptions used to calculate fair value of stock options
Weighted-average expected volatility	75.51%	68.90%
Expected term (in years)	5 years 6 months	5 years 6 months
Risk-free interest rate	0.37%	1.39%
Maximum
Assumptions used to calculate fair value of stock options
Weighted-average expected volatility	82.08%	110.50%
Expected term (in years)	6 years 3 months	10 years
Risk-free interest rate	1.51%	2.69%

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Income Taxes - Reconciliation (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of the U.S. statutory income tax rate to the Company's effective tax rate
Federal income tax (benefit) at statutory rate	21.00%	21.00%
Permanent differences	(0.41%)	(0.57%)
Federal research and development credits and adjustments	2.78%	2.42%
State income tax, net of federal benefit	6.03%	5.50%
Other	0.37%	0.49%
Change in valuation allowance	(29.77%)	(28.85%)
Effective income tax rate	0.00%	0.00%

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Income Taxes - Deferred tax assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets
Net operating loss carryforwards	$ 65,373	$ 55,283
Tax credit carryforwards	9,273	8,030
Capitalized research and development	482	922
Capitalized legal expenses	1,070	1,073
Lease liability	284	639
Other differences	1,648	1,453
Total deferred tax assets	78,130	67,400
Deferred tax liabilities
ROU asset	(262)	(639)
Valuation allowance	(77,868)	(66,761)
Net deferred tax assets	0	0
Increase in valuation allowance	$ 11,100	$ 7,600

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Income Taxes - Operating Loss Carryforwards (Details) $ in Millions	Dec. 31, 2020 USD ($)
Federal
Operating loss carryforwards
Net operating loss	$ 240.1
Tax credit carryforwards	7.4
Federal | Tax Years 2023 through 2039
Operating loss carryforwards
Net operating loss	150.5
Federal | No expiration
Operating loss carryforwards
Net operating loss	89.6
State
Operating loss carryforwards
Net operating loss	236.7
Tax credit carryforwards	2.4
State | Tax Years 2023 through 2039
Operating loss carryforwards
Net operating loss	$ 236.7

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Subsequent Events - Merger Agreement and Stock Purchase Agreement (Details) - USD ($)		12 Months Ended
	Jan. 28, 2021	Dec. 31, 2020	Dec. 31, 2019
Subsequent Events
Aggregate shares sold under purchase agreement		$ 16,270,000	$ 6,996,000
Common Stock
Subsequent Events
Aggregate shares sold under purchase agreement		$ 3,000	$ 1,000
Subsequent Events | Series X Preferred Stock | Quellis Biosciences, Inc
Subsequent Events
Shares issued upon merger (in shares)	50,504
Warrants to purchase number of shares	2,805
Exercise Price (in dollars per share)	$ 341.70
Subsequent Events | Common Stock | Quellis Biosciences, Inc
Subsequent Events
Shares issued upon merger (in shares)	3,332,669
Share price (in dollars per share)	$ 0.001
Warrants to purchase number of shares	185,136
Exercise Price (in dollars per share)	$ 0.35
Conversion value	$ 122,700,000
Subsequent Events | Stock Purchase Agreement | Series X Preferred Stock
Subsequent Events
Aggregate shares sold under purchase agreement	35,573
Purchase price	110,000,000
Subsequent Events | Stock Purchase Agreement | Common Stock | Series X Preferred Stock
Subsequent Events
Purchase price	$ 1,000

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Subsequent Events - Series X Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Millions	Mar. 04, 2021	Jan. 28, 2021	Dec. 31, 2020	Dec. 31, 2019
Subsequent Events
Preferred stock, outstanding			0	0
Common Stock Issuable Upon Conversion			20,084,337	12,433,600
Subsequent Events
Subsequent Events
Percentage of beneficial ownership initially, after conversion		9.99%
Subsequent Events | Registration Rights Agreement
Subsequent Events
Period to prepare and file a resale registration statement with the SEC.		90 days
Period to cause the registration statement to be declared effective by the SEC		30 days
Period to cause the registration statement to be declared effective by the SEC after review		60 days
Subsequent Events | Series X Preferred Stock
Subsequent Events
Preferred stock, outstanding		88,882,000
Redemption price per share	$ 2.87
Payments on redemption of preferred stock	$ 247.0
Subsequent Events | Outstanding shares issued in merger
Subsequent Events
Preferred stock, outstanding		50,504,000
Common Stock Issuable Upon Conversion		50,504,000,000
Subsequent Events | Outstanding shares issued in February 2021 Financing
Subsequent Events
Preferred stock, outstanding		35,573,000
Common Stock Issuable Upon Conversion		35,573,000,000
Subsequent Events | Warrants assumed in merger
Subsequent Events
Preferred stock, outstanding		2,805,000
Common Stock Issuable Upon Conversion		2,805,000,000
Subsequent Events | Series X Common shares, As converted
Subsequent Events
Common Stock Issuable Upon Conversion		88,882,000,000
Subsequent Events | Minimum
Subsequent Events
Percentage of beneficial ownership thereafter, after conversion		4.99%
Subsequent Events | Maximum
Subsequent Events
Percentage of beneficial ownership thereafter, after conversion		19.99%