Summary of Significant Accounting Policies

Liquidity Matters

The Company has incurred net losses since its inception and anticipates net losses and negative operating cash flows for the near future. The Company had a net loss of $179.9 million for the six months ended June 30, 2021 and an accumulated deficit of $1.1 billion as of June 30, 2021. As of June 30, 2021, the Company had $63.0 million in cash, cash equivalents, and restricted cash, $517.4 million in marketable securities, $50.0 million of outstanding balance of the Credit Line (as defined in Note 10, Debt) including accrued interest, and $287.5 million outstanding principal balance of its 2.25% Convertible Senior Notes (the “Convertible Notes”). In April 2020, the Company used a portion of the net proceeds from the offering of the Convertible Notes to repay its obligations under its 2017 Term Loan with OrbiMed.

While the Company has introduced multiple products that are generating revenues, these revenues have not been sufficient to fund all operations. Accordingly, the Company has funded the portion of operating costs that exceeds revenues through a combination of equity issuances, debt issuances, and other financings.

The Company continues to develop and commercialize future products and, consequently, it will need to generate additional revenues to achieve future profitability and may need to raise additional equity or debt financing. If the Company raises additional funds by issuing equity securities, its stockholders will experience dilution. Additional debt financing, if available, may involve covenants restricting its operations or its ability to incur additional debt. Any additional debt financing or additional equity that the Company raises may contain terms that are not favorable to it or its stockholders and requires significant debt service payments, which diverts resources from other activities. Additional financing may not be available at all, or in amounts or on terms acceptable to the Company. If the Company is unable to obtain additional financing, it may be required to delay the development and commercialization of its products and significantly scale back its business and operations.

In May 2021, the Company entered into a development and option agreement with a third party that requires the third party to use its best efforts to perform an agreed upon development plan and provides the Company with an exclusive option to purchase the third party’s assets. The Company paid the third party $10 million in the second quarter of 2021 for conducting the development work and for entering into the agreement, and if the Company elects to exercise its option, the Company has agreed to pay the third party an additional $290 million for the designated assets. There is no assurance that the development plan will be successful, or that the Company will elect to exercise its option to purchase the third party’s assets or, if the Company exercises this option, that it will derive the anticipated benefit from the acquisition of these assets.

In April 2019, the Company completed an underwritten equity offering and sold 6,052,631 shares of its common stock at a price of $19 per share to the public. Before offering expenses of $0.6 million, the Company received proceeds of $108.1 million net of the underwriting discount. In October 2019, the Company completed another underwritten equity offering and sold 6,571,428 shares of its common stock at a price of $35 per share to the public. Before offering expenses of $0.4 million, the Company received proceeds of $216.2 million net of the underwriting discount. In September 2020, the Company completed an additional underwritten equity offering and sold 4,791,665 shares of its common stock at a price of $60.00 per share to the public. Before offering expenses of $0.3 million, the Company received proceeds of $271.0 million net of the underwriting discount. In July 2021, the Company completed an underwritten equity offering and sold 5,175,000 shares of its common stock at a price of $113 per share to the public. Before offering expenses of $0.4 million, the Company received proceeds of $551.2 million net of the underwriting discount. Based on the Company’s current business plan, the Company believes that its existing cash and marketable securities will be sufficient to meet its anticipated cash requirements for at least 12 months after August 5, 2021.

Use of Estimates

The preparation of financial statements in accordance with generally accepted accounting principles (GAAP) in the United States requires management to make estimates and assumptions about future events that affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities, and reported amounts of revenues and expenses. Significant items subject to such estimates include the allowance for doubtful accounts calculated based on the average selling price expected to be received from insurance payors, the operating right-of-use assets and the associated lease liabilities, deferred revenues associated with unsatisfied performance obligations, accrued liability for potential refund requests, the valuation of the Convertible Notes, stock-based compensation, the fair value of common stock, income tax uncertainties, and the expected consideration to be received from contracts with customers. These estimates and assumptions are based on management's best estimates and judgment. Management regularly evaluates its estimates and assumptions using historical experience and other factors, including contractual terms and statutory limits; however, actual results could differ from these estimates and could have an adverse effect on the Company's financial statements.

Investments

Investments consist primarily of debt securities such as U.S. Treasuries, U.S. agency and municipal bonds. Management determines the appropriate classification of securities at the time of purchase and re-evaluates such determination at each balance sheet date. The Company generally classifies its entire investment portfolio as available-for-sale. The Company views its available-for-sale portfolio as available for use in current operations. Accordingly, the Company classifies all investments as short-term, irrespective of maturity date. Available-for-sale securities are carried at

fair value, with unrealized gains and losses reported in accumulated other comprehensive income (loss), which is a separate component of stockholders’ equity.

Accumulated Other Comprehensive Income (Loss)

Comprehensive loss and its components encompass all changes in equity other than those with stockholders, and include net loss, unrealized gains and losses on available-for-sale marketable securities.


	Three months ended				Six months ended
	June 30,				June 30,
	2021		2020		2021		2020

	(in thousands)				(in thousands)
Beginning balance	$	3,197	$	5,666	$	4,259	$	919
Net unrealized gain (loss) on available-for-sale securities, net of tax		(756)		104		(1,818)		4,851
Ending balance	$	2,441	$	5,770	$	2,441	$	5,770