Zogenix (ZGNX) 10-Q 5 Nov 21 2021 Q3 Quarterly report Financial data

Cover

Cover - shares	9 Months Ended
	Sep. 30, 2021	Oct. 27, 2021
Cover [Abstract]
Document type	10-Q
Document quarterly report	true
Document period end date	Sep. 30, 2021
Document transition report	false
Entity file number	001-34962
Entity registrant name	ZOGENIX, INC.
Entity incorporation, state or country code	DE
Entity tax identification number	20-5300780
Entity address, address line one	5959 Horton Street
Entity address, address line two	Suite 500
Entity address, city or town	Emeryville
Entity address, state or province	CA
Entity address, postal zip code	94608
City area code	510
Local phone number	550-8300
Title of 12(b) security	Common Stock, par value $0.001 per share
Trading symbol	ZGNX
Security exchange name	NASDAQ
Entity current reporting status	Yes
Entity interactive data current	Yes
Entity filer category	Large Accelerated Filer
Entity small business	false
Entity emerging growth company	false
Entity shell company	false
Entity common stock, shares outstanding		55,992,086
Entity central index key	0001375151
Amendment flag	false
Document fiscal year focus	2021
Document fiscal period focus	Q3
Current fiscal year end date	--12-31

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 106,138	$ 166,916
Marketable securities	236,886	338,193
Accounts receivable, net	9,486	3,824
Inventory	3,502	1,026
Prepaid expenses	13,950	7,279
Other current assets	5,500	4,936
Total current assets	375,462	522,174
Property and equipment, net	7,593	8,724
Operating lease right-of-use assets	6,862	7,748
Intangible asset, net	92,644	98,558
Goodwill	6,234	6,234
Other non-current assets	8,192	7,692
Total assets	496,987	651,130
Current liabilities:
Accounts payable	12,113	11,945
Accrued and other current liabilities	46,111	54,964
Deferred revenue, current	5,048	5,318
Current portion of operating lease liabilities	1,654	1,688
Current portion of contingent consideration	13,500	8,800
Total current liabilities	78,426	82,715
Deferred revenue, noncurrent	3,436	5,479
Operating lease liabilities, net of current portion	9,055	10,314
Contingent consideration, net of current portion	25,900	33,600
Convertible senior notes	155,871	149,353
Total liabilities	272,688	281,461
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.001 par value; 10,000 shares authorized; none issued and outstanding	0	0
Common stock and additional paid-in capital, $0.001 par value: 200,000 and 100,000 shares authorized and 55,935 and 55,736 shares issued and outstanding at September 30, 2021 and December 31, 2020, respectively	1,721,694	1,694,580
Accumulated deficit	(1,497,370)	(1,324,840)
Accumulated other comprehensive loss	(25)	(71)
Total stockholders’ equity	224,299	369,669
Total liabilities and stockholders’ equity	$ 496,987	$ 651,130

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Preferred stock par value (usd per share)	$ 0.001	$ 0.001
Preferred stock authorized (shares)	10,000,000	10,000,000
Preferred stock issued (shares)	0	0
Preferred stock outstanding (shares)	0	0
Common stock par value (usd per share)	$ 0.001	$ 0.001
Common stock authorized (shares)	200,000,000	100,000,000
Common stock issued (shares)	55,935,000	55,736,000
Common stock outstanding (shares)	55,935,000	55,736,000

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Net product sales	$ 21,398	$ 1,520	$ 51,269	$ 1,520
Collaboration revenue	1,212	1,340	3,813	3,621
Total revenues	22,610	2,860	55,082	5,141
Costs and expenses:
Cost of product sales (excluding amortization of intangible asset)	1,294	140	3,192	140
Research and development	33,255	34,425	100,868	102,038
Selling, general and administrative	39,559	24,583	104,713	70,332
Intangible asset amortization	1,972	1,971	5,914	1,971
Acquired in-process research and development costs	0	1,500	0	4,500
Change in fair value of contingent consideration	400	1,800	1,500	6,100
Total costs and expenses	76,480	64,419	216,187	185,081
Loss from operations	(53,870)	(61,559)	(161,105)	(179,940)
Other income (expense), net:
Interest income	85	934	579	2,504
Interest expense	(3,848)	0	(11,373)	0
Other, net	(371)	536	(631)	20,798
Total other (expense) income, net	(4,134)	1,470	(11,425)	23,302
Loss before income taxes	(58,004)	(60,089)	(172,530)	(156,638)
Income tax benefit	0	0	0	(17,425)
Net loss	$ (58,004)	$ (60,089)	$ (172,530)	$ (139,213)
Net loss per share, basic and diluted
Net loss per share, basic (in dollars per share)	$ (1.04)	$ (1.08)	$ (3.09)	$ (2.62)
Net loss per share, diluted (in dollars per share)	$ (1.04)	$ (1.08)	$ (3.09)	$ (2.62)
Weighted average number of shares used in the calculation of basic net loss per common share (in shares)	55,905	55,548	55,831	53,039
Weighted average number of shares used in the calculation of diluted net loss per common share (in shares)	55,905	55,548	55,831	53,039

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net loss	$ (58,004)	$ (60,089)	$ (172,530)	$ (139,213)
Other comprehensive income (loss):
Change in net unrealized gains (losses) related to marketable securities	(15)	(255)	(183)	17
Foreign currency translation adjustments	114	(69)	229	(98)
Total other comprehensive (loss) income	99	(324)	46	(81)
Comprehensive loss	$ (57,905)	$ (60,413)	$ (172,484)	$ (139,294)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Shares of Common Stock	Common Stock and Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Stockholders' Equity - Beginning Balance at Dec. 31, 2019	$ 245,059		$ 1,360,137	$ (1,115,457)	$ 379
Stockholders' Equity - Beginning Balance (in shares) at Dec. 31, 2019		45,272
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(25,800)			(25,800)
Other comprehensive income (loss)	(167)				(167)
Issuance of common stock, net of offering costs	221,708		221,708
Issuance of common stock, net of offering costs (in shares)		9,798
Issuance of common stock under employee equity plans	3,882		3,882
Issuance of common stock under employee equity plans (in shares)		297
Shares repurchased to satisfy tax withholding obligation of vesting restricted stock units	(569)		(569)
Shares repurchased to satisfy tax withholding obligation of vesting restricted stock units (in shares)		(26)
Stock-based compensation	6,394		6,394
Stockholders' Equity - Ending Balance at Mar. 31, 2020	450,507		1,591,552	(1,141,257)	212
Stockholders' Equity - Ending Balance (in shares) at Mar. 31, 2020		55,341
Stockholders' Equity - Beginning Balance at Dec. 31, 2019	245,059		1,360,137	(1,115,457)	379
Stockholders' Equity - Beginning Balance (in shares) at Dec. 31, 2019		45,272
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(139,213)
Stockholders' Equity - Ending Balance at Sep. 30, 2020	422,092		1,676,464	(1,254,670)	298
Stockholders' Equity - Ending Balance (in shares) at Sep. 30, 2020		55,673
Stockholders' Equity - Beginning Balance at Mar. 31, 2020	450,507		1,591,552	(1,141,257)	212
Stockholders' Equity - Beginning Balance (in shares) at Mar. 31, 2020		55,341
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(53,324)			(53,324)
Other comprehensive income (loss)	410				410
Issuance of common stock under employee equity plans	616		616
Issuance of common stock under employee equity plans (in shares)		153
Shares repurchased to satisfy tax withholding obligation of vesting restricted stock units	(1,369)		(1,369)
Shares repurchased to satisfy tax withholding obligation of vesting restricted stock units (in shares)		(49)
Stock-based compensation	8,303		8,303
Stockholders' Equity - Ending Balance at Jun. 30, 2020	405,143		1,599,102	(1,194,581)	622
Stockholders' Equity - Ending Balance (in shares) at Jun. 30, 2020		55,445
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(60,089)			(60,089)
Other comprehensive income (loss)	(324)				(324)
Issuance of common stock, net of offering costs	4,866		4,866
Issuance of common stock, net of offering costs (in shares)		202
Equity component of convertible senior notes	65,482		65,482
Issuance of common stock under employee equity plans	91		91
Issuance of common stock under employee equity plans (in shares)		35
Shares repurchased to satisfy tax withholding obligation of vesting restricted stock units	(218)		(218)
Shares repurchased to satisfy tax withholding obligation of vesting restricted stock units (in shares)		(9)
Stock-based compensation	7,141		7,141
Stockholders' Equity - Ending Balance at Sep. 30, 2020	422,092		1,676,464	(1,254,670)	298
Stockholders' Equity - Ending Balance (in shares) at Sep. 30, 2020		55,673
Stockholders' Equity - Beginning Balance at Dec. 31, 2020	369,669		1,694,580	(1,324,840)	(71)
Stockholders' Equity - Beginning Balance (in shares) at Dec. 31, 2020		55,736
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(55,630)			(55,630)
Other comprehensive income (loss)	34				34
Issuance of common stock under employee equity plans	6		6
Issuance of common stock under employee equity plans (in shares)		120
Shares repurchased to satisfy tax withholding obligation of vesting restricted stock units	(896)		(896)
Shares repurchased to satisfy tax withholding obligation of vesting restricted stock units (in shares)		(43)
Stock-based compensation	8,098		8,098
Stockholders' Equity - Ending Balance at Mar. 31, 2021	321,281		1,701,788	(1,380,470)	(37)
Stockholders' Equity - Ending Balance (in shares) at Mar. 31, 2021		55,813
Stockholders' Equity - Beginning Balance at Dec. 31, 2020	369,669		1,694,580	(1,324,840)	(71)
Stockholders' Equity - Beginning Balance (in shares) at Dec. 31, 2020		55,736
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(172,530)
Stockholders' Equity - Ending Balance at Sep. 30, 2021	224,299		1,721,694	(1,497,370)	(25)
Stockholders' Equity - Ending Balance (in shares) at Sep. 30, 2021		55,935
Stockholders' Equity - Beginning Balance at Mar. 31, 2021	321,281		1,701,788	(1,380,470)	(37)
Stockholders' Equity - Beginning Balance (in shares) at Mar. 31, 2021		55,813
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(58,896)			(58,896)
Other comprehensive income (loss)	(87)				(87)
Issuance of common stock under employee equity plans	1,036		1,036
Issuance of common stock under employee equity plans (in shares)		78
Stock-based compensation	9,526		9,526
Stockholders' Equity - Ending Balance at Jun. 30, 2021	272,860		1,712,350	(1,439,366)	(124)
Stockholders' Equity - Ending Balance (in shares) at Jun. 30, 2021		55,891
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(58,004)			(58,004)
Other comprehensive income (loss)	99				99
Issuance of common stock under employee equity plans	295		295
Issuance of common stock under employee equity plans (in shares)		53
Shares repurchased to satisfy tax withholding obligation of vesting restricted stock units	(133)		(133)
Shares repurchased to satisfy tax withholding obligation of vesting restricted stock units (in shares)		(9)
Stock-based compensation	9,182		9,182
Stockholders' Equity - Ending Balance at Sep. 30, 2021	$ 224,299		$ 1,721,694	$ (1,497,370)	$ (25)
Stockholders' Equity - Ending Balance (in shares) at Sep. 30, 2021		55,935

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net loss	$ (172,530)	$ (139,213)
Adjustments to reconcile net loss to net cash used in operating activities
Stock-based compensation	25,776	21,838
Depreciation and amortization	7,092	3,106
Deferred income taxes	0	(17,425)
Amortization of debt discount and issuance costs	6,518	0
Acquired in-process research and development expense	0	4,500
Change in fair value of contingent consideration liability	1,500	6,100
Other non-cash items, net	833	169
Changes in operating assets and liabilities:
Accounts receivable	(5,662)	(1,309)
Inventory	(1,446)	(1,010)
Prepaid expenses and other current assets	(7,235)	(3,321)
Other non-current assets	(500)	(1,761)
Accounts payable, accrued and other current liabilities	6,585	541
Contingent consideration	(1,500)	0
Operating lease liabilities	(1,293)	(975)
Deferred revenue	(2,313)	(621)
Net cash used in operating activities	(144,175)	(129,381)
Cash flows from investing activities:
Cash paid for in-process research and development asset	0	(4,500)
Purchases of marketable securities	(317,228)	(283,208)
Proceeds from maturities of marketable securities	404,904	232,142
Proceeds from sale of marketable securities	13,500	12,987
Purchases of property and equipment	(87)	(657)
Net cash (used in) provided by investing activities	101,089	(43,236)
Cash flows from financing activities:
Payment of contingent consideration	(18,000)	(15,000)
Proceeds from issuance of common stock under equity incentive plans	1,337	4,589
Payments of tax withholding obligation on vesting restricted stock units	(1,029)	(2,157)
Net proceeds from issuance of convertible senior notes	0	194,000
Proceeds from issuance of common stock, net of issuance costs	0	226,575
Net cash (used in) provided by financing activities	(17,692)	408,007
Net (decrease) increase in cash and cash equivalents	(60,778)	235,390
Cash and cash equivalents, beginning of the period	166,916	62,070
Cash and cash equivalents, end of the period	106,138	297,460
Supplemental disclosure of non-cash investing and financing activities:
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 0	$ 1,156

Organization, Basis of Presenta

Organization, Basis of Presentation and Liquidity	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Basis of Presentation and Liquidity	Organization, Basis of Presentation and Liquidity Zogenix, Inc., and subsidiaries (also referred to as Zogenix, we, our or us) is a global biopharmaceutical company committed to developing and commercializing therapies with the potential to transform the lives of patients and their families living with rare diseases. Our first rare disease therapy, Fintepla (fenfluramine) oral solution, has been approved by the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) for the treatment of seizures associated with Dravet syndrome, a rare, devastating, severe lifelong epilepsy. Fintepla is also currently under development in Japan. We also have two late-stage development programs underway: one for Fintepla for the treatment of seizures associated with Lennox-Gastaut syndrome (LGS), a rare childhood-onset epilepsy, and another for MT1621, an investigational novel substrate enhancement therapy for the treatment of TK2 deficiency, a rare genetic disorder. We operate as a single operating segment engaged in the research, development and commercialization of pharmaceutical products, and our headquarters are located in Emeryville, California. Basis of Presentation The accompanying condensed consolidated financial statements have been prepared pursuant to generally accepted accounting principles in the United States (GAAP) for interim financial reporting and the rules and regulations of the Securities and Exchange Commission (SEC). The condensed consolidated financial statements do not include all of the information and note disclosures required by GAAP for complete financial statements and should therefore be read in conjunction with the consolidated financial statements and related notes included in our 2020 Annual Report on Form 10-K (2020 Form 10-K), which was filed with the SEC on March 1, 2021. In the opinion of management, these condensed consolidated financial statements reflect all adjustments, which are normal and recurring in nature, necessary for a fair statement of our financial position, results of operations and cash flows for the periods indicated. The results of operations for any interim period are not necessarily indicative of results of operations for any future period. The accompanying condensed consolidated financial statements include the accounts of Zogenix, Inc. and its wholly-owned subsidiaries. Intercompany accounts and transactions have been eliminated in consolidation. Liquidity As of September 30, 2021, our cash, cash equivalents and marketable securities totaled $343.0 million. Excluding gains from two discrete business divestitures, we have incurred significant net losses and negative cash flows from operating activities since inception, resulting in an accumulated deficit of $1.5 billion as of September 30, 2021. We expect to continue to incur significant operating losses and negative cash flows from operations to support the sales and marketing of Fintepla for Dravet syndrome in the U.S. and Europe, potential commercialization of Fintepla for LGS, as well as continuing to advance our clinical programs. Additionally, we are obligated to pay royalties on sales as well as make future milestone payments that are contingent upon the successful achievement of certain development, regulatory and sales-based milestone events related to Fintepla and MT1621. Historically, we have relied primarily on the proceeds from equity and convertible debt offerings to finance our operations. Until such time, if ever, we can generate a sufficient amount of revenue to finance our cash requirements, we may need to continue to rely on additional financing to achieve our business objectives. However, we may not be able to secure such financing in a timely manner or on favorable terms, if at all, and this risk could be exacerbated by the impact of the ongoing COVID-19 pandemic on global economic conditions. Failure to raise sufficient capital when needed could require us to significantly delay, scale back or discontinue one or more of our product development programs or commercialization efforts or other aspects of our business plans, and our operating results and financial condition would be adversely affected.

Accounting Policies

Accounting Policies	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Accounting Policies	Accounting Policies Use of Estimates The preparation of our condensed consolidated financial statements requires us to make estimates, judgments and assumptions that may affect the reported amounts of assets, liabilities, equity, revenues and expenses and related disclosure of contingent assets and liabilities. On an ongoing basis we evaluate our estimates, judgments and methodologies. We base our estimates on historical experience and on various other assumptions that we believe are reasonable, the results of which form the basis for making judgments about the carrying values of assets, liabilities and equity and the amount of revenues and expenses. Actual results may differ from those estimates. Significant Accounting Policies The significant accounting policies and estimates used in the preparation of the accompanying condensed consolidated financial statements are described in Note 2, Summary of Significant Accounting Policies to the consolidated financial statements in our 2020 Form 10-K. There have been no material changes in our significant accounting policies during the nine months ended September 30, 2021. Recently Issued Accounting Pronouncements Not Yet Adopted Account Standard Update (ASU) 2020-06, Debt — Debt with Conversion and Other Options (subtopic 470-20) and Derivatives and Hedging — Contracts in Entity’s Own Equity (subtopic 815-40) (ASU 2020-06) simplifies the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible debt instruments with cash conversion features. Specifically, ASU 2020-06 removes the existing guidance that we currently follow for our convertible senior notes, which requires entities to account for cash conversion features in equity separately from the host contract. These amendments are expected to result in more freestanding financial instruments qualifying for equity classification and, as a result, not accounted for as derivatives, as well as fewer embedded features requiring separate accounting from the host contract. In addition, ASU 2020-06 eliminates the treasury stock method when calculating diluted earnings per share for convertible instruments that can be settled in whole or in part with equity and requires the use of the if-converted method. Early adoption is permitted, but no earlier than the fiscal year beginning after December 15, 2020. The standard can be applied using a full or modified retrospective approach. ASU 2020-06 will be effective for us as of January 1, 2022. When effective, we expect the accounting for our convertible senior notes as a single unit of account will: i) increase the carrying value of our convertible notes to be closer to its outstanding principal balance, ii) decrease our interest expense over the expected life of the financial instrument, and iii) result in the debt instrument’s effective interest rate to be closer to the stated coupon rate. In addition, the use of the more favorable treasury stock method, which allows an entity with a stated policy of settling convertible instruments with a combination of cash and shares to exclude shares issuable upon conversion that it expects to settle with cash when calculating diluted earnings per share, is no longer permitted. Even if we have the intent and ability to settle conversions by paying the conversion value in cash up to the principal amount being converted and any excess in shares, the adoption of ASU 2020-06 will require that we presume such instruments will be settled by issuance of shares (the “if-converted method”). As a result, our diluted earnings per share under ASU 2020-06 may be lower than if we were able to apply the treasury stock method when calculating the dilutive effect of our Notes in earnings per share. We will adopt the new guidance in the annual period beginning January 1, 2022, on a modified retrospective basis. On the date of adoption, we expect to record a net decrease to additional paid-in capital of approximately $75.3 million to remove the equity component separately recorded for the conversion features associated with the convertible debt instruments and equity component associated with the issuance costs, an increase of approximately $65.6 million in the carrying value of our senior convertible notes to reflect the full principal amount of the Notes outstanding net of issuance costs, and a decrease of approximately $9.7 million to accumulated deficit. These preliminary estimates could change as we continue with our implementation efforts. We do not expect an impact to the our statements of operations or cash flows as the result of the adoption of this ASU.

Product Revenue and Concentrati

Product Revenue and Concentration of Credit Risks	9 Months Ended
	Sep. 30, 2021
Disaggregation of Revenue [Abstract]
Product Revenue and Concentration of Credit Risks	Product Revenue and Concentration of Credit Risks Net Product Sales Fintepla is distributed in the U.S. through an exclusive arrangement with a specialty distributor, who is our customer. The specialty distributor subsequently resells our product through its related specialty pharmacy provider to patients and health care providers. Separately, we have or may enter into payment arrangements with various third-party payers including pharmacy benefit managers, private healthcare insurers and government healthcare programs who provide coverage and reimbursement for our products that have been proscribed to a patient. We distribute Fintepla in Europe (currently, in Germany and France) through a third-party logistics provider (3PL) for distribution to pharmacies in those countries. The pharmacies are our customers, who subsequently resell our product directly to patients and health care providers. For the three months ended September 30, 2021, total net product sales for Fintepla were $21.4 million and consisted of U.S. product sales of $18.4 million, with the remainder from sales in Europe. For the nine months ended September 30, 2021, total net product sales for Fintepla were $51.3 million and consisted of U.S. product sales of $45.3 million, with the remainder from sales in Europe. For the three and nine months ended September 30, 2020, total net product sales for Fintepla of $1.5 million were generated in the United States. Fintepla was approved by the FDA in June 2020 and the EMA in December 2020. We record product revenue at the net sales price (transaction price), which includes estimates of consideration payable to our customers and third-party payers for which reserves are established and that result from government rebates, chargebacks, co-pay assistance, prompt-payment discounts and other allowances that are offered under arrangements between us, our customers, and third-party payers related to the sales of Fintepla. The following table summarizes the provisions, and credits/payments, for sales-related deductions. (In thousands) Rebates Trade Discounts, Distributor Fees and Other Total Balance at December 31, 2020 $ 1,161 $ 129 $ 1,290 Current period provisions 7,134 1,903 9,037 Payments/credits (4,402) (1,773) (6,175) Balance at September 30, 2021 $ 3,893 $ 259 $ 4,152 We generally invoice our customers and recognize revenue once our performance obligations are satisfied, at which point payment is unconditional. Accordingly, our arrangements with customers did not give rise to contract assets or liabilities during the nine months ended September 30, 2021. Concentration of Credit Risk and Major Customers

Collaboration Arrangement

Collaboration Arrangement	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaboration Arrangement	Collaboration Arrangement Nippon Shinyaku Co., Ltd In March 2019, we entered into an agreement (Shinyaku Agreement) with Nippon Shinyaku Co., Ltd. (Shinyaku) for the exclusive distribution of Fintepla in Japan for the treatment of Dravet syndrome and LGS. No development rights or intellectual property licenses were transferred. As part of the Shinyaku Agreement, we are responsible for completing the global clinical development and all regulatory approval activities for Fintepla to support the submission of new drug applications in Japan for Dravet syndrome and LGS. Upon regulatory approval of Fintepla in Japan, Shinyaku will act as our exclusive distributor for Fintepla and will be responsible for the commercialization activities including the promotion, marketing, sale and distribution of Fintepla in Japan. Shinyaku has agreed to support development and regulatory approval of Fintepla in Japan by actively participating in the design of non-clinical, clinical and manufacturing requirements needed for regulatory submission, actively planning and participating in product labeling decisions and discussions with the Japanese Ministry of Health, Labor and Welfare (MHLW) and obtained distribution exclusivity through the payment of an initial fixed consideration. The collaborative activities under the Shinyaku Agreement prior to regulatory approval are within the scope of the accounting guidance related to collaborative arrangements. Pursuant to the terms of the agreement, Shinyaku agreed to make aggregate fixed payments of $20.0 million in scheduled installments over a two-year period from the date of the agreement. As of September 30, 2021, all fixed consideration has been received. In addition, we can earn up to $66.0 million from Shinyaku for the achievement of certain regulatory milestones for the treatment of Dravet syndrome and LGS of which $3.0 million will be due to us upon our submission of an NDA in Japan (J-NDA) to Japan’s Pharmaceutical and Medical Devices Agency for Dravet syndrome. At contract inception and through September 30, 2021, the regulatory milestone variable consideration was fully constrained as the achievement of the events tied to these regulatory milestone payments was highly dependent on factors outside our control. We can earn up to an additional $42.5 million tied to the achievement of certain net sales milestones by Shinyaku through the term of the agreement, which generally expires in 2045. Shinyaku will only become a customer and subject to revenue from contracts from customers accounting guidance after regulatory approval of Fintepla in Japan occurs and Shinyaku places purchase orders with us. To date, Shinyaku has not provided us with any purchase orders and thus no revenue has been recognized for the supply of Fintepla. For the three and nine months ended September 30, 2021, collaboration revenue under this arrangement was $1.2 million and $3.8 million, respectively, as compared to the same periods in 2020 of $1.3 million and $3.6 million, respectively. As of September 30, 2021, the deferred revenue balance of $8.5 million was classified as either current or net of current portion in the accompanying condensed consolidated balance sheets based on the period over which the collaboration revenue is expected to be recognized. We expect to recognize collaboration revenue related to these collaborative activities through the end of 2023.

Strategic License Agreements

Strategic License Agreements	9 Months Ended
	Sep. 30, 2021
Research and Development [Abstract]
Strategic License Agreements	Strategic License Agreements Universities of Antwerp and Leuven in Belgium (the Universities) As a result of our 2014 acquisition of Brabant Pharma Limited, we have a collaboration and license agreement with the Universities (the Universities Agreement) that runs through September 2045. Under the terms of the agreement, the Universities granted us an exclusive worldwide license to use the data obtained from a study related to low-dose fenfluramine for the treatment of Dravet syndrome or certain related conditions stemming from infantile epilepsy such as LGS, as well as certain other intellectual property. We are required to pay a mid-single-digit percentage royalty on net sales of products containing low-dose fenfluramine for the treatment of Dravet syndrome or, in the case of a sublicense of products containing low-dose fenfluramine for the treatment of Dravet syndrome, a percentage in the mid-twenties of the sub-licensing revenues. Subsequent to the execution of the March 2019 Shinyaku Agreement beginning in late 2019, we have been in discussions with the Universities to address the portion of the payments the Universities are entitled to, if any, related to proceeds we received or may receive under the Shinyaku Agreement from Nippon Shinyaku. In October 2021, we reached an agreement to modify the Universities Agreement and make a one-time payment of $7.0 million related to our previous collaboration activities and consideration received to date under the Shinyaku Agreement. We also agreed to pay the Universities 15% of future regulatory milestone collaboration consideration and sales-based milestone consideration we receive, as well as amending the method of calculating royalties due from sale of Fintepla distributed in Japan. The payment of $7.0 million has been recorded within accrued and other current liabilities in the condensed consolidated balance sheet at September 30, 2021. For the three and nine months ended September 30, 2021, the $7.0 million was recorded within research and development expense as a cost of our Shinyaku Agreement and as Fintepla has not yet been approved for marketing in Japan. Tevard Collaboration, Option and License Agreement In October 2019, we entered into an option agreement with Tevard Biosciences (Tevard), a privately-held company focused on advancing novel gene therapies and other genetic epilepsies. In December 2020, we exercised the option on Tevard’s Dravet syndrome program and entered into a collaboration, option and license agreement with Tevard (the Tevard Agreement) and will be responsible for funding preclinical studies and clinical development for this program. The financial terms of the Tevard Agreement included an upfront payment of $5.2 million. In connection with the transaction, we also purchased a convertible promissory note issued by Tevard in the amount of $5.0 million. The note matures in December 2022 and carries interest at 3.5% per year. The note will automatically convert into equity securities issued by Tevard upon the occurrence of an equity financing transaction at a conversion price equal to the price paid per share by other investors of the financing transaction. For the three and nine months ended September 30, 2021, costs incurred to reimburse Tevard’s Dravet syndrome program of $0.8 million and $2.4 million were recorded as research and development expense. For the three and nine months ended September 30, 2020, option maintenance fees of $1.5 million and $4.5 million incurred prior to our opt-in of Tevard’s Dravet syndrome program in December 2020 were immediately expensed to acquired in-process research and development costs. At the inception of the agreement and through September 30, 2021, Tevard is a variable interest entity in which we held variable interests through our licensed Dravet syndrome program and convertible promissory note. We determined that we are not the primary beneficiary of Tevard as we do not have voting control or other forms of power to direct activities that most significantly impact Tevard’s economic performance. At each reporting period, we evaluate the note receivable for current expected credit loss by considering factors such as historical experience, market data, issuer-specific factors, and current economic conditions. As of September 30, 2021, no provision for current expected credit losses was deemed necessary based on the expected timing of an equity financing that would result in the automatic conversion of the note to equity securities of Tevard and their existing cash on hand was sufficient to meet their operating requirements prior to the consummation of a financing transaction. As of September 30, 2021, we do not have any current legal or contractual obligations to provide financing to Tevard and our maximum exposure to future loss is limited to the $5.0 million note receivable. While we have committed to fund the Dravet syndrome development program for Tevard’s early discovery activities, our obligation to fund these efforts is contingent upon continued involvement in the program and/or the lack of any adverse events which could cause the discontinuance of the program. Our exposure to future losses is limited as we have the unilateral right to terminate the agreement with 180 days advanced notice.

Cash, Cash Equivalents and Mark

Cash, Cash Equivalents and Marketable Securities	9 Months Ended
	Sep. 30, 2021
Cash and Cash Equivalents [Abstract]
Cash, Cash Equivalents and Marketable Securities	Cash, Cash Equivalents and Marketable Securities The following tables summarize the amortized cost and the estimated fair value of our cash, cash equivalents and marketable securities as of September 30, 2021 and December 31, 2020: September 30, 2021 (In thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Current assets: Cash $ 29,269 $ — $ — $ 29,269 Cash equivalents: Money market funds 39,422 — — 39,422 Commercial paper 35,444 — — 35,444 Corporate debt securities 2,003 — — 2,003 Total cash equivalents 76,869 — — 76,869 Total cash and cash equivalents 106,138 — — 106,138 Marketable securities: U.S. Treasuries 15,510 1 — 15,511 Certificate of deposits 41,874 — — 41,874 Commercial paper 158,837 — — 158,837 U.S. Government-sponsored enterprises debt securities 6,200 5 — 6,205 Corporate debt securities 14,459 2 (2) 14,459 Total marketable securities 236,880 8 (2) 236,886 Total cash, cash equivalents and marketable securities $ 343,018 $ 8 $ (2) $ 343,024 December 31, 2020 (In thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Current assets: Cash $ 23,887 $ — $ — $ 23,887 Cash equivalents: Money market funds 80,986 — — 80,986 Commercial paper 61,043 — — 61,043 Certificate of deposits 1,000 — — 1,000 Total cash equivalents 143,029 — — 143,029 Total cash and cash equivalents 166,916 — — 166,916 Marketable securities: U.S. Treasuries 43,050 1 (1) 43,050 Commercial paper 210,986 — — 210,986 Certificate of deposits 44,480 — — 44,480 U.S. Government-sponsored enterprises debt securities 6,200 17 — 6,217 Corporate debt securities 33,288 172 — 33,460 Total marketable securities 338,004 190 (1) 338,193 Total cash, cash equivalents and marketable securities $ 504,920 $ 190 $ (1) $ 505,109 As of September 30, 2021, all marketable securities held have maturity dates within one year or less. We regularly review our available-for-sale marketable securities in an unrealized loss position and evaluate the current expected credit loss by considering factors such as historical experience, market data, issuer-specific factors, and current economic conditions. As of September 30, 2021, the aggregate difference between the amortized cost and fair value of each security in an unrealized loss position was de minimis. Since any provision for expected credit losses for a security held is limited to the amount the fair value is less than its amortized cost, no allowance for expected credit loss was deemed necessary at September 30, 2021. See Note 7 for further information regarding the fair value of our financial instruments.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. A three-level valuation hierarchy has been established under GAAP for disclosure of fair value measurements. The valuation hierarchy is based on the transparency of inputs to the valuation of an asset or liability as of the measurement date. The three levels are defined as follows: Level 1: Observable inputs such as quoted prices in active markets; Level 2: Inputs, other than the quoted prices in active markets, that are observable either directly or indirectly; and Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. The following tables summarize assets and liabilities recognized or at fair value on a recurring basis as of September 30, 2021 and December 31, 2020: September 30, 2021 (In thousands) Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 39,422 $ — $ — $ 39,422 Commercial paper — 35,444 — 35,444 Corporate debt securities — 2,003 — $ 2,003 Marketable securities: U.S. Treasuries — 15,511 — 15,511 Certificate of deposits — 41,874 — 41,874 Commercial paper — 158,837 — 158,837 U.S. Government-sponsored enterprises debt securities — 6,205 — 6,205 Corporate debt securities — 14,459 — 14,459 Total (1) $ 39,422 $ 274,333 $ — $ 313,755 Liabilities: Contingent consideration $ — $ — $ 39,400 $ 39,400 December 31, 2020 (In thousands) Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 80,986 $ — $ — $ 80,986 Commercial paper — 61,043 — 61,043 Certificate of deposits — 1,000 — 1,000 Marketable securities: U.S. Treasuries — 43,050 43,050 Commercial paper — 210,986 210,986 Certificate of deposits — 44,480 44,480 U.S. Government-sponsored enterprises debt securities — 6,217 6,217 Corporate debt securities — 33,460 — 33,460 Total (1) $ 80,986 $ 400,236 $ — $ 481,222 Liabilities: Contingent consideration $ — $ — $ 42,400 $ 42,400 ———————————— (1) Fair value is determined by taking into consideration valuations obtained from third-party pricing services. The third-party pricing services utilize industry standard valuation models, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include reported trades of and broker/dealer quotes on the same or similar securities; issuer credit spreads; benchmark securities; and other observable inputs. Contingent Consideration Liability As of September 30, 2021, our contingent consideration liability consisted of sales-based milestones for Fintepla, which resulted from our 2014 acquisition of Brabant. The maximum amount of future contingent consideration (undiscounted) that we could be required to pay was $40.5 million. The following table provides a reconciliation of our contingent consideration liability measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the three and nine months ended September 30, 2021 and 2020 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Balance at beginning of period $ 39,000 $ 53,100 $ 42,400 $ 63,800 Change in fair value 400 1,800 1,500 6,100 Settlements — — (4,500) (15,000) Balance at end of period $ 39,400 $ 54,900 $ 39,400 $ 54,900 For the three and nine months ended September 30, 2021, the increases to the estimated fair value of the contingent consideration liability primarily reflects the interest component of contingent consideration related to the passage of time. The following table summarizes the significant unobservable inputs used in the fair value measurement of our contingent consideration liability as of September 30, 2021. Fair Value as of Valuation Technique Unobservable Input Range Weighted Average (1) Discount rate 0.0% — 2.0% 1.0% $39,400 Discounted cash flow Probability of payment 100% 100% Projected year of payment 2022 — 2023 2022 ———————————— (1) Unobservable inputs were weighted by the relative fair value of each sales-based milestone payment. Fair Value Disclosures Some of our financial instruments are not measured at fair value on a recurring basis but are recorded at amounts that approximate fair value due to their short-term nature. Such financial assets and financial liabilities include accounts receivable, promissory note receivable, certain other current assets, accounts payable and accrued liabilities. Convertible Senior Notes As of September 30, 2021 and December 31, 2020, the estimated fair value of our convertible senior notes due 2027 was approximately $227.0 million and $260.5 million, respectively, and was determined based on a binomial lattice model with Level 2 inputs. When determining the estimated fair value of the Notes, we utilize a binomial lattice model which incorporates the terms and conditions of our convertible senior notes and market-based risk measurements that are indirectly observable, such as credit risk. The lattice model produces an estimated fair value based on changes in the price of the underlying common stock price over successive periods of time. An estimated yield based on comparable non-convertible debt instruments in the market is used to discount the cash flows.

Intangible Asset

Intangible Asset	9 Months Ended
	Sep. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Asset	Intangible Asset Our intangible asset consists of worldwide development, commercialization and related intellectual property rights including patents and licenses for Fintepla, our first rare disease therapy approved for marketing in the U.S. and Europe. The following table provides details of the carrying amount of our finite-lived intangible asset: (In thousands) September 30, 2021 December 31, 2020 Finite-lived intangible asset $ 102,500 $ 102,500 Accumulated amortization (9,856) (3,942) Total intangible asset, net $ 92,644 $ 98,558 As of September 30, 2021 and December 31, 2020, the carrying value of the intangible asset will be amortized over its estimated remaining useful life of 11.8 years and 12.5 years, respectively. At September 30, 2021, the estimated amortization expense for each of the five succeeding years was approximately $7.9 million per year.

Balance Sheet Details

Balance Sheet Details	9 Months Ended
	Sep. 30, 2021
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Details	Balance Sheet Details Inventory The following table provides details of our inventory balance: (In thousands) September 30, 2021 December 31, 2020 Raw materials $ 1,011 $ 391 Work in process 1,299 243 Finished goods 1,192 392 Total $ 3,502 $ 1,026 Accrued and Other Current Liabilities The following table provides details of accrued and other current liabilities: (In thousands) September 30, 2021 December 31, 2020 Accrued clinical trial expenses $ 13,272 $ 16,477 Accrued compensation 12,243 10,917 Accrued milestone payment — 15,000 Other accrued liabilities 20,596 12,570 Total $ 46,111 $ 54,964

Convertible Senior Notes

Convertible Senior Notes	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Convertible Senior Notes	Convertible Senior Notes In September and October 2020, we issued $230.0 million aggregate principal amount of 2.75% convertible senior notes due 2027 (the Notes) and realized net proceeds of $222.5 million. The Notes are governed by an indenture (Indenture), dated as of September 28, 2020, between Zogenix and U.S. Bank National Association, as trustee. Under the Indenture, the Notes are senior, unsecured obligations of Zogenix, are equal in right of payment with its future senior, unsecured indebtedness of Zogenix, and structurally subordinated to all indebtedness and liabilities of its subsidiaries. Interest is payable semi-annually in arrears on April 1 and October 1 of each year, beginning on April 1, 2021 at a rate of 2.75% per year. The Notes mature on October 1, 2027, unless earlier repurchased, redeemed or converted. The Indenture contains customary terms and covenants and may become due and payable upon the occurrence of an event of default, but does not contain any financial covenants. As of September 30, 2021, we were in compliance with all covenants under the Indenture. The Notes are convertible, subject to certain conditions described below, into shares of our common stock at an initial conversion rate of 41.1794 shares per $1,000 principal amount of the Notes, which represents an initial conversion price of approximately $24.28 per share, subject to adjustments upon the occurrence of certain events. Certain corporate events described in the Indenture may increase the conversion rate for holders who elect to convert their Notes upon the occurrence of certain corporate events. We also may choose to repurchase outstanding Notes through open-market transactions, including through a Rule 10b5-1 trading plan to facilitate open-market repurchases, or otherwise, from time to time. Holders may convert the Notes in multiples of $1,000 principal amount at any time prior to October 1, 2027, but only in the following circumstances: • during any calendar quarter ending after December 31, 2020, if our closing stock price exceeds 130% of the conversion price on each of at least 20 trading days of the last 30 consecutive trading days of the immediately preceding calendar quarter; • during the five consecutive business day period after any 10 consecutive trading day period in which the Notes’ trading price is less than 98% of the product of our closing stock price times the conversion rate; or • the occurrence of certain corporate events, such as a change of control, merger, default or liquidation. In addition, holders may also convert their Notes at their option at any time beginning on July 1, 2027 until the close of business on the second scheduled trading day immediately before the maturity date for the Notes, without regard to the foregoing circumstances. Upon conversion, we will pay or deliver, as the case may be, cash, shares of our common stock or a combination thereof at our election. We may not redeem the Notes prior to October 7, 2024. On or after October 7, 2024, the Notes are redeemable for cash, in whole or in part (subject to minimum redemption amounts), at our option at any time, and from time to time, before the 40th scheduled trading day immediately before October 1, 2027, at a cash redemption price equal to 100% of the principal amount of the Notes to be redeemed, plus accrued and unpaid interest, if any, but only if our closing stock price exceeds 130% of the conversion price on (1) each of at least 20 trading days, whether or not consecutive, during the 30 consecutive trading days ending on, and including, the trading day immediately before the date we send the related redemption notice; and (2) the trading day immediately before the date we send such notice. In addition, calling any Note for redemption will constitute a make-whole fundamental change (as defined in the Indenture) with respect to that Note, in which case the conversion rate applicable to the conversion of that Note will be increased in certain circumstances if it is converted after it is called for redemption. In accounting for the issuance of the Notes, we separated the Notes between a liability component and an equity component utilizing applicable accounting guidance for convertible instruments that may be settled with a combination of cash and shares, at our election. This resulted in the recognition of $152.1 million as the liability component of the Notes. The carrying amount of the equity component of approximately $77.9 million, representing the conversion option, was determined by deducting the fair value of the liability component from the principal amount of the Notes. The difference between the principal amount of the Notes and the liability component (the debt discount) is amortized to interest expense using the effective interest method over the expected term of the Notes. The equity component of the Notes is included in additional paid-in capital in the condensed consolidated balance sheets. In accounting for debt issuance costs, we allocated the total amount incurred of $7.5 million to the liability and equity components using the same proportions as the principal amount of the Notes. Debt issuance costs attributable to the liability component of $4.9 million were recorded as debt discount and are being amortized to interest expense over the expected term of the Notes. Debt issuance costs attributable to the equity component of approximately $2.6 million were netted with the equity component within our condensed consolidated stockholders' equity. The equity component balance of $75.3 million, net of allocated issuance costs, is not remeasured as long as the conversion option of the Notes continues to meet the conditions for equity classification. As of September 30, 2021, there have been no changes to the net carrying value of the equity component balance since the date of issuance of the Notes. The following table provides additional details on the carrying amounts of the Notes: (in thousands) September 30, 2021 December 31, 2020 Liability component: Principal amount of Notes $ 230,000 $ 230,000 Less: unamortized debt discount and issuance costs (74,129) (80,647) Net carrying amount of Notes $ 155,871 $ 149,353 Equity component — net carrying amount $ 75,333 $ 75,333 For the three and nine months ended September 30, 2021, total interest expense recognized related to the Notes consists of the following: (in thousands) Three Months Ended Nine Months Ended Contractual coupon interest 1,581 4,777 Amortization of debt discount and issuance costs 2,238 6,518 Total interest expense $ 3,819 $ 11,295 For the three and nine months ended September 30, 2021, the effective interest rate on the liability component of the Notes was 9.9%, which remained unchanged from the date of issuance. The unamortized debt discount and issuance costs of $74.1 million as of September 30, 2021 will be amortized over the estimated remaining term of approximately 6.0 years. Interest expense related to the Notes was not material for the same periods in 2020. During the third quarter of 2021, the closing price of our common stock did not exceed 130% of the applicable conversion price of the Notes on at least 20 of the last 30 consecutive trading days of the quarter; furthermore, no other conditions allowing holders of the Notes to convert were met as of September 30, 2021. Therefore, the Notes are not convertible for the fourth quarter of 2021 and are classified as long-term debt. Should the closing price conditions be met in a future quarter, the Notes will be convertible at the holders’ option during the immediately following quarter. Based on the closing price of our common stock of $15.19 per share on September 30, 2021, the if-converted value of the Notes was less than the outstanding principal balance.

Common Stock and Stock-Based Co

Common Stock and Stock-Based Compensation	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Common Stock and Stock-Based Compensation	Common Stock and Stock-Based Compensation Increase in Authorized Shares of Common Stock In May 2021, our stockholders approved an amendment to our Fifth Amended and Restated Certificate of Incorporation to increase the total number of authorized shares of our common stock from 100,000,000 to 200,000,000 shares. The increase in the authorized common shares was effected pursuant to a Certificate of Amendment of our Fifth Amended and Restated Certificate of Incorporation filed with the State of Delaware on May 28, 2021 and was effective as of such date. 2010 Equity Incentive Award Plan Under our 2010 Equity Incentive Award Plan, as amended and restated effective May 22, 2019 (the Prior 2010 Plan), the aggregate number of shares with respect to which awards may be granted was 11,500,000 shares. The various types of awards that may be granted include stock options, stock appreciation rights, restricted stock units, restricted stock and other stock-based awards, any of which may be performance-based. In May 2021, our board of directors adopted, and our stockholders approved, an amendment and restatement of the Prior 2010 Plan. The 2010 Equity Incentive Award Plan, as amended and restated effective May 27, 2021 (the 2010 Plan), increased the aggregate number of shares authorized for issuance under the plan from 11,500,000 to 16,000,000 shares, and an extension of the expiration date of the Prior 2010 Plan from March 2029 to May 2031. 2021 Employment Inducement Equity Incentive Award Plan In May 2021, our board of directors approved the adoption of the Zogenix, Inc. 2021 Employment Inducement Equity Incentive Award Plan (2021 Inducement Plan), pursuant to which we reserved 1,000,000 shares of our common stock (subject to customary adjustments in the event of a change in capital structure). The 2021 Inducement Plan provides for the grant of non-statutory stock options, restricted stock units and other incentive awards and was adopted without stockholder approval pursuant to Rule 5635(c)(4) of the Nasdaq Listing Rules. The terms and conditions of the 2021 Inducement Plan are substantially similar to our 2010 Plan, but with such other terms and conditions intended to comply with the Nasdaq inducement award rules. In accordance with Rule 5635(c)(4) of the Nasdaq Listing Rules, the only persons eligible to receive grants of equity awards under the 2021 Inducement Plan are individuals who were not previously a Zogenix employee or director, or following a bona fide period of non-employment, as an inducement material to such persons entering into employment with us. Stock Options The following is a summary of stock option activity for the nine months ended September 30, 2021 (in thousands, except per share data): Shares Weighted- Average Exercise Price per Share Outstanding at December 31, 2020 5,311 $ 29.12 Granted 1,625 18.21 Exercised (50) 9.77 Canceled (330) 28.73 Outstanding at September 30, 2021 6,556 $ 26.58 Restricted Stock Units Time-based restricted stock units (RSUs) and performance-based restricted stock units (PSUs) will be settled with our common stock on a one-to-one basis upon vesting. The following is a summary of our stock award activity for the nine months ended September 30, 2021 (in thousands, except per share data): RSUs PSUs Total Outstanding at December 31, 2020 393 — 393 Granted (1) 533 494 1,027 Vested (144) — (144) Canceled (47) (36) (83) Outstanding at September 30, 2021 735 458 1,193 (1) Weighted-average grant date fair value $ 18.11 $ 19.53 $ 18.79 For the nine months ended September 30, 2021, we granted approximately 494,000 PSUs to employees and executive officers. The PSUs are subject to vesting based on various performance conditions including achievement of certain regulatory milestones, net product revenue targets and the number of patients on reimbursed therapy, subject to continued service by the employee. Compensation expense related to equity-based awards with performance conditions and terms that provide for a graded vesting schedule is recognized over the requisite service period on a straight-line basis for each separately vesting tranche of the award, and is based on the expected satisfaction of the performance conditions at each reporting date. For performance conditions associated with regulatory milestones, we determined the outcome is not probable of being achieved unless and until the occurrence of the event. As a result, compensation expense will only be recognized, at a point in time, when regulatory approval occurs. We expect stock-based compensation will fluctuate from period to period based on the timing of achievement of regulatory milestones and such fluctuations may be material. For performance conditions associated with the net product revenue and the number of patients receiving reimbursed therapy, we determined the outcome is probable of being achieved and stock-based compensation expense is recognized commencing at the grant date over the implicit service period. The following table summarizes the components of total stock-based compensation expense included in our condensed consolidated statements of operations: Three Months Ended September 30, Nine Months Ended September 30, (In thousands) 2021 2020 2021 2020 Research and development $ 2,905 $ 2,865 $ 10,729 $ 9,082 Selling, general and administrative 5,247 4,276 15,047 12,756 Total $ 8,152 $ 7,141 $ 25,776 $ 21,838 Stock-based compensation of $1.0 million was capitalized into inventory for the three and nine months ended September 30, 2021. The following table summarizes stock-based compensation expense by award type included in our condensed consolidated statements of operations: Three Months Ended September 30, Nine Months Ended September 30, (In thousands) 2021 2020 2021 2020 Time-based stock options and RSUs $ 6,962 $ 5,507 23,171 19,923 Performance-based stock units 1,066 1,441 2,120 1,441 Employee stock purchase plan (ESPP) 124 193 485 474 Total $ 8,152 $ 7,141 $ 25,776 $ 21,838 Shares reserved and available for future issuance under all employee equity plans as of September 30, 2021 and December 31, 2020 were approximately 7.1 million shares and 3.9 million shares, respectively.

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing net loss by the weighted average number of shares outstanding for the period. Diluted net loss per share is calculated by dividing net loss by the weighted average number of shares of common stock and potential dilutive common stock equivalents outstanding during the period if the effect is dilutive. Our potentially dilutive shares of common stock include outstanding stock options, restricted stock units, warrants to purchase common stock and rights under the Notes. A reconciliation of the numerators and denominators used in computing net loss per share is as follows (in thousands, except per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Numerator: Net loss $ (58,004) $ (60,089) $ (172,530) $ (139,213) Denominator: Shares used in per share calculation 55,905 55,548 55,831 53,039 Net loss per share, basic and diluted $ (1.04) $ (1.08) $ (3.09) $ (2.62) The following table presents the potential shares of common stock outstanding that were excluded from the calculation of diluted net loss per share for the periods presented because including them would have been anti-dilutive (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Shares subject to outstanding stock options 6,534 5,149 6,118 4,848 Shares subject to outstanding restricted stock units 1,173 422 1,032 487 Shares subject to outstanding warrants to purchase common stock 6 28 21 28 Shares issuable upon conversion of Notes 9,430 269 9,430 90 Total 17,143 5,868 16,601 5,453

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income TaxesWe record a tax provision or benefit for interim periods using an estimated annual effective tax rate. This rate is applied to the current year-to-date pre-tax income or loss to determine the income tax provision or benefit allocated to the interim period. The income tax effects of unusual or infrequent items including a change in the valuation allowance as a result of a change in judgment about the realizability of the related deferred tax asset are excluded from the estimated annual effective tax rate and are required to be discretely recognized in the interim period they occur.For the three and nine months ended September 30, 2021 and the three months ended September 30, 2020, there was no provision for income taxes as we incurred pretax losses and maintained a full valuation allowance against our net deferred tax assets for these periods. For the nine months ended September 30, 2020, our income tax benefit consisted of a discrete income tax adjustment related to the completion of our in-process research program upon approval of Fintepla for marketing by the FDA. Until June 2020, our net deferred tax liability was related to book and tax basis differences for our indefinite-lived Fintepla IPR&D intangible asset that was acquired through the October 2014 acquisition of Brabant Pharma Limited. Previously, this deferred tax liability was not considered to be a source of income for purposes of establishing our deferred tax asset valuation allowance due to the uncertainty associated with the timing of reversals for this temporary tax difference. Upon FDA approval of Fintepla in June 2020, the indefinite-lived asset was reclassified to a finite-lived intangible asset and was subject to amortization over its estimated useful life. Because the detail scheduling of the timing of reversal for this temporary tax difference became available, the deferred tax liability associated with this finite-lived intangible asset was considered to be a source of income when assessing the realizability of our deferred tax assets. We therefore recorded a $17.4 million income tax benefit for the nine months ended September 30, 2020 with a corresponding reduction to our valuation allowance on our deferred tax assets. The income tax benefit included the effects of foreign exchange differences on remeasurement of the deferred tax liability. An immaterial portion of the adjustment for foreign exchange differences was related to prior periods.

United Kingdom (U.K.) Research

United Kingdom (U.K.) Research and Development (R&D) Tax Relief Scheme	9 Months Ended
	Sep. 30, 2021
Other Income and Expenses [Abstract]
United Kingdom (U.K.) Research and Development (R&D) Tax Relief Scheme	United Kingdom (U.K.) Research and Development (R&D) Tax Relief SchemeWe conduct extensive research and development activities that benefit from U.K.’s small and medium-sized enterprises (SMEs) R&D tax relief scheme. Under this tax relief scheme, a SME can make an election (i) to receive an enhanced U.K. tax deduction on its eligible R&D activities or, when an SME entity is in a net operating loss position, or (ii) to surrender net operating losses that arise from its eligible R&D activities in exchange for a cash payment from the U.K. tax authorities. As the tax incentives may be received without regard to an entity’s actual tax liability, they are not subject to accounting for income taxes. Amounts recognized by us for cash payment claims under the SME R&D tax relief scheme are recorded as a component of other income after an election for tax relief has been made by submitting a claim for a discrete tax year and collectability is deemed probable and reasonably assured.In December 2019, we elected to surrender net operating losses by submitting claims to receive cash payments of $9.9 million and $9.8 million related to our 2017 and 2018 tax years, respectively. Upon approval of our submitted claims by the U.K. tax authorities in the first quarter of 2020, we recorded income of $19.7 million as a component of other income on the condensed consolidated statement of operations. For our 2019 tax year, we have not amended our tax return by surrendering some of our losses for a tax credit cash rebate claim or elect to receive an enhanced U.K. tax deduction on our eligible R&D activities. Under the U.K.’s tax legislation, any claims must be submitted within two years from the end of a tax year.

Litigation

Litigation	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Litigation	Litigation On July 21, 2021, we received a letter dated July 20, 2021, notifying us that Apotex Inc. and Apotex Corp. (collectively, “Apotex”) submitted to FDA an abbreviated new drug application (“ANDA”) for a generic version of 2.2 mg base/ml Fintepla (fenfluramine hydrochloride) that included “Paragraph IV” certifications (pursuant to 21 U.S.C. § 355(j)(2)(A)(vii)(IV)) with respect to two of our patents covering Fintepla, U.S. Patent Nos. 10,603,290, expiration date August 2, 2037; and 10,452,815, expiration date June 29, 2038. These patents are listed in FDA’s list of Approved Drug Products with Therapeutic Equivalence Evaluations, commonly referred to as the Orange Book, for Fintepla. The letter included a statement setting forth the basis for Apotex’s opinion that these patents are invalid and/or will not be infringed by the manufacture, use or sale of Apotex’s fenfluramine hydrochloride oral solution, 2.2 mg base/ml product. On August 30, 2021, we filed a complaint against Apotex Inc. and Apotex Corp. for infringement based on these Paragraph IV certifications. On October 13, 2021, we received a letter dated October 12, 2021 notifying us that Apotex had amended its ANDA and submitted additional Paragraph IV certifications with respect to two additional Orange Book-listed patents covering Fintepla, U.S. Patent Nos. 10,950,331, expiration date September 28, 2035; and 10,947,183, expiration date December 20, 2036. The letter included a statement setting forth the basis for Apotex’s opinion that these two additional patents are also invalid and/or will not be infringed by the manufacture, use or sale of Apotex’s fenfluramine hydrochloride oral solution, 2.2 mg base/ml product. On October 28, 2021, we filed a second complaint against Apotex Inc. and Apotex Corp. for infringement based on these additional paragraph IV certifications. On August 31, 2021, we received a letter dated August 27, 2021 notifying us that Lupin Limited (“Lupin”) submitted to FDA an abbreviated new drug application (“ANDA”) for a generic version of 2.2 mg base/ml Fintepla (fenfluramine hydrochloride) that contains “Paragraph IV” certifications (pursuant to 21 U.S.C. § 355(j)(2)(A)(vii)(IV)) with respect to seven of our patents covering Fintepla, U.S. Patent Nos. 9,549,909, expiration date May 3, 2033; 9,603,814, expiration date May 3, 2033; 9,603,815, expiration date May 3, 2033; 9,610,260, expiration date May 3, 2033; 10,478,441, expiration date May 3, 2033; 10,478,442, expiration date May 3, 2033; and 10,947,183, expiration date December 20, 2036 (collectively, "the Asserted Patents"). These patents are listed in FDA’s list of Approved Drug Products with Therapeutic Equivalence Evaluations, commonly referred to as the Orange Book, for Fintepla. The letter included a statement setting forth the basis for Apotex’s opinion that these patents are invalid and/or will not be infringed by the manufacture, use or sale of Lupin’s fenfluramine hydrochloride oral solution, 2.2 mg base/ml product. On October 6, 2021, we filed a complaint against Lupin for infringement based on the Paragraph IV certifications. Fintepla has Orphan Drug exclusivity, which prevents FDA from approving an ANDA referencing Fintepla until June 25, 2027. We intend to vigorously enforce our intellectual property rights relating to Fintepla. We cannot predict the ultimate outcome of these actions, and we may spend significant resources enforcing and defending these patents. If we are unsuccessful, some or all of our claims in the patents may be narrowed or invalidated and the patent protection for our products could be shortened, allowing for the sale of generic versions of these products earlier than their patent expiration, which could have a significant negative effect on our revenues and results of operations.

Accounting Policies (Policies)

Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of our condensed consolidated financial statements requires us to make estimates, judgments and assumptions that may affect the reported amounts of assets, liabilities, equity, revenues and expenses and related disclosure of contingent assets and liabilities. On an ongoing basis we evaluate our estimates, judgments and methodologies. We base our estimates on historical experience and on various other assumptions that we believe are reasonable, the results of which form the basis for making judgments about the carrying values of
Recently Issued Accounting Pronouncements Not Yet Adopted	Recently Issued Accounting Pronouncements Not Yet Adopted Account Standard Update (ASU) 2020-06, Debt — Debt with Conversion and Other Options (subtopic 470-20) and Derivatives and Hedging — Contracts in Entity’s Own Equity (subtopic 815-40) (ASU 2020-06) simplifies the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible debt instruments with cash conversion features. Specifically, ASU 2020-06 removes the existing guidance that we currently follow for our convertible senior notes, which requires entities to account for cash conversion features in equity separately from the host contract. These amendments are expected to result in more freestanding financial instruments qualifying for equity classification and, as a result, not accounted for as derivatives, as well as fewer embedded features requiring separate accounting from the host contract. In addition, ASU 2020-06 eliminates the treasury stock method when calculating diluted earnings per share for convertible instruments that can be settled in whole or in part with equity and requires the use of the if-converted method. Early adoption is permitted, but no earlier than the fiscal year beginning after December 15, 2020. The standard can be applied using a full or modified retrospective approach. ASU 2020-06 will be effective for us as of January 1, 2022. When effective, we expect the accounting for our convertible senior notes as a single unit of account will: i) increase the carrying value of our convertible notes to be closer to its outstanding principal balance, ii) decrease our interest expense over the expected life of the financial instrument, and iii) result in the debt instrument’s effective interest rate to be closer to the stated coupon rate. In addition, the use of the more favorable treasury stock method, which allows an entity with a stated policy of settling convertible instruments with a combination of cash and shares to exclude shares issuable upon conversion that it expects to settle with cash when calculating diluted earnings per share, is no longer permitted. Even if we have the intent and ability to settle conversions by paying the conversion value in cash up to the principal amount being converted and any excess in shares, the adoption of ASU 2020-06 will require that we presume such instruments will be settled by issuance of shares (the “if-converted method”). As a result, our diluted earnings per share under ASU 2020-06 may be lower than if we were able to apply the treasury stock method when calculating the dilutive effect of our Notes in earnings per share. We will adopt the new guidance in the annual period beginning January 1, 2022, on a modified retrospective basis. On the date of adoption, we expect to record a net decrease to additional paid-in capital of approximately $75.3 million to remove the equity component separately recorded for the conversion features associated with the convertible debt instruments and equity component associated with the issuance costs, an increase of approximately $65.6 million in the carrying value of our senior convertible notes to reflect the full principal amount of the Notes outstanding net of issuance costs, and a decrease of approximately $9.7 million to accumulated deficit. These preliminary estimates could change as we continue with our implementation efforts. We do not expect an impact to the our statements of operations or cash flows as the result of the adoption of this ASU.
Fair Value Measurements	Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. A three-level valuation hierarchy has been established under GAAP for disclosure of fair value measurements. The valuation hierarchy is based on the transparency of inputs to the valuation of an asset or liability as of the measurement date. The three levels are defined as follows: Level 1: Observable inputs such as quoted prices in active markets; Level 2: Inputs, other than the quoted prices in active markets, that are observable either directly or indirectly; and Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions.
Net Loss Per Share	Basic net loss per share is calculated by dividing net loss by the weighted average number of shares outstanding for the period. Diluted net loss per share is calculated by dividing net loss by the weighted average number of shares of common stock and potential dilutive common stock equivalents outstanding during the period if the effect is dilutive. Our potentially dilutive shares of common stock include outstanding stock options, restricted stock units, warrants to purchase common stock and rights under the Notes.

Product Revenue and Concentra_2

Product Revenue and Concentration of Credit Risks (Tables)	9 Months Ended
	Sep. 30, 2021
Disaggregation of Revenue [Abstract]
Schedule of revenue provisions, and credits or payments for sales-related deductions	The following table summarizes the provisions, and credits/payments, for sales-related deductions. (In thousands) Rebates Trade Discounts, Distributor Fees and Other Total Balance at December 31, 2020 $ 1,161 $ 129 $ 1,290 Current period provisions 7,134 1,903 9,037 Payments/credits (4,402) (1,773) (6,175) Balance at September 30, 2021 $ 3,893 $ 259 $ 4,152

Cash, Cash Equivalents and Ma_2

Cash, Cash Equivalents and Marketable Securities (Tables)	9 Months Ended
	Sep. 30, 2021
Cash and Cash Equivalents [Abstract]
Amortized cost and fair value of cash, cash equivalents and marketable securities	The following tables summarize the amortized cost and the estimated fair value of our cash, cash equivalents and marketable securities as of September 30, 2021 and December 31, 2020: September 30, 2021 (In thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Current assets: Cash $ 29,269 $ — $ — $ 29,269 Cash equivalents: Money market funds 39,422 — — 39,422 Commercial paper 35,444 — — 35,444 Corporate debt securities 2,003 — — 2,003 Total cash equivalents 76,869 — — 76,869 Total cash and cash equivalents 106,138 — — 106,138 Marketable securities: U.S. Treasuries 15,510 1 — 15,511 Certificate of deposits 41,874 — — 41,874 Commercial paper 158,837 — — 158,837 U.S. Government-sponsored enterprises debt securities 6,200 5 — 6,205 Corporate debt securities 14,459 2 (2) 14,459 Total marketable securities 236,880 8 (2) 236,886 Total cash, cash equivalents and marketable securities $ 343,018 $ 8 $ (2) $ 343,024 December 31, 2020 (In thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Current assets: Cash $ 23,887 $ — $ — $ 23,887 Cash equivalents: Money market funds 80,986 — — 80,986 Commercial paper 61,043 — — 61,043 Certificate of deposits 1,000 — — 1,000 Total cash equivalents 143,029 — — 143,029 Total cash and cash equivalents 166,916 — — 166,916 Marketable securities: U.S. Treasuries 43,050 1 (1) 43,050 Commercial paper 210,986 — — 210,986 Certificate of deposits 44,480 — — 44,480 U.S. Government-sponsored enterprises debt securities 6,200 17 — 6,217 Corporate debt securities 33,288 172 — 33,460 Total marketable securities 338,004 190 (1) 338,193 Total cash, cash equivalents and marketable securities $ 504,920 $ 190 $ (1) $ 505,109

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Assets measured at fair value on recurring basis	The following tables summarize assets and liabilities recognized or at fair value on a recurring basis as of September 30, 2021 and December 31, 2020: September 30, 2021 (In thousands) Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 39,422 $ — $ — $ 39,422 Commercial paper — 35,444 — 35,444 Corporate debt securities — 2,003 — $ 2,003 Marketable securities: U.S. Treasuries — 15,511 — 15,511 Certificate of deposits — 41,874 — 41,874 Commercial paper — 158,837 — 158,837 U.S. Government-sponsored enterprises debt securities — 6,205 — 6,205 Corporate debt securities — 14,459 — 14,459 Total (1) $ 39,422 $ 274,333 $ — $ 313,755 Liabilities: Contingent consideration $ — $ — $ 39,400 $ 39,400 December 31, 2020 (In thousands) Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 80,986 $ — $ — $ 80,986 Commercial paper — 61,043 — 61,043 Certificate of deposits — 1,000 — 1,000 Marketable securities: U.S. Treasuries — 43,050 43,050 Commercial paper — 210,986 210,986 Certificate of deposits — 44,480 44,480 U.S. Government-sponsored enterprises debt securities — 6,217 6,217 Corporate debt securities — 33,460 — 33,460 Total (1) $ 80,986 $ 400,236 $ — $ 481,222 Liabilities: Contingent consideration $ — $ — $ 42,400 $ 42,400 ————————————
Liabilities measured at fair value on recurring basis	The following tables summarize assets and liabilities recognized or at fair value on a recurring basis as of September 30, 2021 and December 31, 2020: September 30, 2021 (In thousands) Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 39,422 $ — $ — $ 39,422 Commercial paper — 35,444 — 35,444 Corporate debt securities — 2,003 — $ 2,003 Marketable securities: U.S. Treasuries — 15,511 — 15,511 Certificate of deposits — 41,874 — 41,874 Commercial paper — 158,837 — 158,837 U.S. Government-sponsored enterprises debt securities — 6,205 — 6,205 Corporate debt securities — 14,459 — 14,459 Total (1) $ 39,422 $ 274,333 $ — $ 313,755 Liabilities: Contingent consideration $ — $ — $ 39,400 $ 39,400 December 31, 2020 (In thousands) Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 80,986 $ — $ — $ 80,986 Commercial paper — 61,043 — 61,043 Certificate of deposits — 1,000 — 1,000 Marketable securities: U.S. Treasuries — 43,050 43,050 Commercial paper — 210,986 210,986 Certificate of deposits — 44,480 44,480 U.S. Government-sponsored enterprises debt securities — 6,217 6,217 Corporate debt securities — 33,460 — 33,460 Total (1) $ 80,986 $ 400,236 $ — $ 481,222 Liabilities: Contingent consideration $ — $ — $ 42,400 $ 42,400 ————————————
Reconciliation of liabilities measured at fair value using significant unobservable inputs (Level 3)	The following table provides a reconciliation of our contingent consideration liability measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the three and nine months ended September 30, 2021 and 2020 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Balance at beginning of period $ 39,000 $ 53,100 $ 42,400 $ 63,800 Change in fair value 400 1,800 1,500 6,100 Settlements — — (4,500) (15,000) Balance at end of period $ 39,400 $ 54,900 $ 39,400 $ 54,900
Significant inputs used in fair value measurement	The following table summarizes the significant unobservable inputs used in the fair value measurement of our contingent consideration liability as of September 30, 2021. Fair Value as of Valuation Technique Unobservable Input Range Weighted Average (1) Discount rate 0.0% — 2.0% 1.0% $39,400 Discounted cash flow Probability of payment 100% 100% Projected year of payment 2022 — 2023 2022 ———————————— (1) Unobservable inputs were weighted by the relative fair value of each sales-based milestone payment.

Intangible Asset (Tables)

Intangible Asset (Tables)	9 Months Ended
	Sep. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of intangible assets	The following table provides details of the carrying amount of our finite-lived intangible asset: (In thousands) September 30, 2021 December 31, 2020 Finite-lived intangible asset $ 102,500 $ 102,500 Accumulated amortization (9,856) (3,942) Total intangible asset, net $ 92,644 $ 98,558

Balance Sheet Details (Tables)

Balance Sheet Details (Tables)	9 Months Ended
	Sep. 30, 2021
Balance Sheet Related Disclosures [Abstract]
Schedule of inventory	The following table provides details of our inventory balance: (In thousands) September 30, 2021 December 31, 2020 Raw materials $ 1,011 $ 391 Work in process 1,299 243 Finished goods 1,192 392 Total $ 3,502 $ 1,026
Details of accrued and other current liabilities	The following table provides details of accrued and other current liabilities: (In thousands) September 30, 2021 December 31, 2020 Accrued clinical trial expenses $ 13,272 $ 16,477 Accrued compensation 12,243 10,917 Accrued milestone payment — 15,000 Other accrued liabilities 20,596 12,570 Total $ 46,111 $ 54,964

Convertible Senior Notes (Table

Convertible Senior Notes (Tables)	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Long-term debt	The following table provides additional details on the carrying amounts of the Notes: (in thousands) September 30, 2021 December 31, 2020 Liability component: Principal amount of Notes $ 230,000 $ 230,000 Less: unamortized debt discount and issuance costs (74,129) (80,647) Net carrying amount of Notes $ 155,871 $ 149,353 Equity component — net carrying amount $ 75,333 $ 75,333 For the three and nine months ended September 30, 2021, total interest expense recognized related to the Notes consists of the following: (in thousands) Three Months Ended Nine Months Ended Contractual coupon interest 1,581 4,777 Amortization of debt discount and issuance costs 2,238 6,518 Total interest expense $ 3,819 $ 11,295

Common Stock and Stock-Based _2

Common Stock and Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Summary of stock option activity	The following is a summary of stock option activity for the nine months ended September 30, 2021 (in thousands, except per share data): Shares Weighted- Average Exercise Price per Share Outstanding at December 31, 2020 5,311 $ 29.12 Granted 1,625 18.21 Exercised (50) 9.77 Canceled (330) 28.73 Outstanding at September 30, 2021 6,556 $ 26.58
Schedule of restricted stock unit activity	The following is a summary of our stock award activity for the nine months ended September 30, 2021 (in thousands, except per share data): RSUs PSUs Total Outstanding at December 31, 2020 393 — 393 Granted (1) 533 494 1,027 Vested (144) — (144) Canceled (47) (36) (83) Outstanding at September 30, 2021 735 458 1,193 (1) Weighted-average grant date fair value $ 18.11 $ 19.53 $ 18.79
Stock-based compensation expense	The following table summarizes the components of total stock-based compensation expense included in our condensed consolidated statements of operations: Three Months Ended September 30, Nine Months Ended September 30, (In thousands) 2021 2020 2021 2020 Research and development $ 2,905 $ 2,865 $ 10,729 $ 9,082 Selling, general and administrative 5,247 4,276 15,047 12,756 Total $ 8,152 $ 7,141 $ 25,776 $ 21,838 Stock-based compensation of $1.0 million was capitalized into inventory for the three and nine months ended September 30, 2021. The following table summarizes stock-based compensation expense by award type included in our condensed consolidated statements of operations: Three Months Ended September 30, Nine Months Ended September 30, (In thousands) 2021 2020 2021 2020 Time-based stock options and RSUs $ 6,962 $ 5,507 23,171 19,923 Performance-based stock units 1,066 1,441 2,120 1,441 Employee stock purchase plan (ESPP) 124 193 485 474 Total $ 8,152 $ 7,141 $ 25,776 $ 21,838

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Basic and diluted net loss per share	A reconciliation of the numerators and denominators used in computing net loss per share is as follows (in thousands, except per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Numerator: Net loss $ (58,004) $ (60,089) $ (172,530) $ (139,213) Denominator: Shares used in per share calculation 55,905 55,548 55,831 53,039 Net loss per share, basic and diluted $ (1.04) $ (1.08) $ (3.09) $ (2.62)
Schedule of antidilutive securities excluded from computation of diluted net loss per share	The following table presents the potential shares of common stock outstanding that were excluded from the calculation of diluted net loss per share for the periods presented because including them would have been anti-dilutive (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Shares subject to outstanding stock options 6,534 5,149 6,118 4,848 Shares subject to outstanding restricted stock units 1,173 422 1,032 487 Shares subject to outstanding warrants to purchase common stock 6 28 21 28 Shares issuable upon conversion of Notes 9,430 269 9,430 90 Total 17,143 5,868 16,601 5,453

Organization, Basis of Presen_2

Organization, Basis of Presentation and Liquidity (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)programsegmentdivestiture	Dec. 31, 2020USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of late-stage development programs | program	2
Number of operating segments | segment	1
Total cash, cash equivalents and short-term investments, estimated fair value	$ 343,024	$ 505,109
Number of discrete business divestitures | divestiture	2
Accumulated deficit	$ 1,497,370	$ 1,324,840

Accounting Policies (Details)

Accounting Policies (Details) - USD ($) $ in Thousands	Jan. 01, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' deficit		$ (224,299)	$ (272,860)	$ (321,281)	$ (369,669)	$ (422,092)	$ (405,143)	$ (450,507)	$ (245,059)
Expected | Accounting Standards Update 2020-06 [Member] | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Senior convertible debt	$ 65,600
Common Stock and Additional Paid-in Capital | Expected | Accounting Standards Update 2020-06 [Member] | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' deficit	75,300
Accumulated Deficit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' deficit		$ 1,497,370	$ 1,439,366	$ 1,380,470	$ 1,324,840	$ 1,254,670	$ 1,194,581	$ 1,141,257	$ 1,115,457
Accumulated Deficit | Expected | Accounting Standards Update 2020-06 [Member] | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' deficit	$ 9,700

Product Revenue and Concentra_3

Product Revenue and Concentration of Credit Risks - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Net product sales	$ 21,398	$ 1,520	$ 51,269	$ 1,520
Fintepla
Disaggregation of Revenue [Line Items]
Net product sales	$ 21,400		$ 51,300
Geographic Concentration Risk | Accounts Receivable | U.S. customer
Disaggregation of Revenue [Line Items]
Concentration of credit risk and major customers (percent)	80.00%		80.00%
Geographic Concentration Risk | Product revenue | U.S. customer
Disaggregation of Revenue [Line Items]
Concentration of credit risk and major customers (percent)	80.00%		80.00%
United States | Fintepla
Disaggregation of Revenue [Line Items]
Net product sales	$ 18,400	$ 1,500	$ 45,300	$ 1,500

Product Revenue and Concentra_4

Product Revenue and Concentration of Credit Risks - Revenue Provisions, and Credits or Payments for Sales-related Deductions (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)
Sales-related Provisions, Credits and Payments [Roll Forward]
Balance at December 31, 2020	$ 1,290
Current period provisions	9,037
Payments/credits	6,175
Balance at September 30, 2021	4,152
Rebates
Sales-related Provisions, Credits and Payments [Roll Forward]
Balance at December 31, 2020	1,161
Current period provisions	7,134
Payments/credits	4,402
Balance at September 30, 2021	3,893
Trade Discounts, Distributor Fees and Other
Sales-related Provisions, Credits and Payments [Roll Forward]
Balance at December 31, 2020	129
Current period provisions	1,903
Payments/credits	1,773
Balance at September 30, 2021	$ 259

Collaboration Arrangement (Deta

Collaboration Arrangement (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		31 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Mar. 31, 2019
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue	$ 1,212	$ 1,340	$ 3,813	$ 3,621
Nippon Shinyaku Co., Ltd. (Shinyaku) | Collaborative arrangement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue	1,200	$ 1,300	3,800	$ 3,600
Deferred revenue	8,500		8,500		$ 8,500
Nippon Shinyaku Co., Ltd. (Shinyaku) | Collaborative arrangement | Fixed consideration
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Performance obligation at inception of arrangement						$ 20,000
Nippon Shinyaku Co., Ltd. (Shinyaku) | Collaborative arrangement | Fixed consideration | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-04-01
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Timing of consideration to be received						2 years
Nippon Shinyaku Co., Ltd. (Shinyaku) | Collaborative arrangement | Achievement of regulatory milestones | Variable consideration
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Amount that can be earned upon achievement of milestone	66,000		66,000		66,000
Regulatory milestone	3,000		3,000		3,000
Nippon Shinyaku Co., Ltd. (Shinyaku) | Collaborative arrangement | Achievement of net sales milestones | Variable consideration
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Amount that can be earned upon achievement of net sales milestone	$ 42,500		$ 42,500		42,500
Nippon Shinyaku Co., Ltd. (Shinyaku) | Collaborative arrangement | Achievement of net sales milestones | Variable consideration | Fintepla
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue					$ 0

Strategic License Agreements (D

Strategic License Agreements (Details) - Strategic license agreement - USD ($) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Oct. 31, 2021	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Oct. 31, 2019
Universities of Antwerp and Leuven in Belgium (the Universities) and Amendment Fee
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Refund liability		$ 7		$ 7
Research and development expense		7		7
Universities of Antwerp and Leuven in Belgium (the Universities) and Amendment Fee | Shinyaku Agreement | Subsequent event
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
One-time amendment fee	$ 7
Future regulatory and sales-based milestones payable rate (percent)	15.00%
Tevard Biosciences (Tevard)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payment						$ 5.2
Promissory notes purchased						$ 5
Stated interest rate (percent)						3.50%
Research and development expense		0.8		2.4
Option maintenance fees			$ 1.5		$ 4.5
Maximum exposure to future loss		$ 5		$ 5
Advance termination notice allowed under the license agreement				180 days

Cash, Cash Equivalents and Ma_3

Cash, Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Cash and Cash Equivalents [Line Items]
Cash	$ 29,269	$ 23,887
Cash equivalents:	76,869	143,029
Total cash and cash equivalents	106,138	166,916
Marketable securities, amortized cost	236,880	338,004
Marketable securities, gross unrealized gains	8	190
Marketable securities, gross unrealized losses	(2)	(1)
Marketable securities, estimated fair value	236,886	338,193
Total cash, cash equivalents and marketable securities, amortized cost	343,018	504,920
Total cash, cash equivalents and marketable securities	343,024	505,109
Money market funds
Cash and Cash Equivalents [Line Items]
Cash equivalents:	39,422	80,986
Commercial paper
Cash and Cash Equivalents [Line Items]
Cash equivalents:	35,444	61,043
Marketable securities, amortized cost	158,837	210,986
Marketable securities, gross unrealized gains	0	0
Marketable securities, gross unrealized losses	0	0
Marketable securities, estimated fair value	158,837	210,986
Corporate debt securities
Cash and Cash Equivalents [Line Items]
Cash equivalents:	2,003
Marketable securities, amortized cost	14,459	33,288
Marketable securities, gross unrealized gains	2	172
Marketable securities, gross unrealized losses	(2)	0
Marketable securities, estimated fair value	14,459	33,460
U.S. Treasuries
Cash and Cash Equivalents [Line Items]
Marketable securities, amortized cost	15,510	43,050
Marketable securities, gross unrealized gains	1	1
Marketable securities, gross unrealized losses	0	(1)
Marketable securities, estimated fair value	15,511	43,050
Certificate of deposits
Cash and Cash Equivalents [Line Items]
Cash equivalents:		1,000
Marketable securities, amortized cost	41,874	44,480
Marketable securities, gross unrealized gains	0	0
Marketable securities, gross unrealized losses	0	0
Marketable securities, estimated fair value	41,874	44,480
U.S. Government-sponsored enterprises debt securities
Cash and Cash Equivalents [Line Items]
Marketable securities, amortized cost	6,200	6,200
Marketable securities, gross unrealized gains	5	17
Marketable securities, gross unrealized losses	0	0
Marketable securities, estimated fair value	$ 6,205	$ 6,217

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities:	$ 236,886,000	$ 338,193,000
Total assets	313,755,000	481,222,000
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	39,422,000	80,986,000
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	274,333,000	400,236,000
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Contingent consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	39,400,000	42,400,000
Contingent consideration | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	0	0
Contingent consideration | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	0	0
Contingent consideration | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	39,400,000	42,400,000
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:	39,422,000	80,986,000
Money market funds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:	39,422,000	80,986,000
Money market funds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:	0	0
Money market funds | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:	0	0
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:	35,444,000	61,043,000
Marketable securities:	158,837,000	210,986,000
Commercial paper | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:	0	0
Marketable securities:	0	0
Commercial paper | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:	35,444,000	61,043,000
Marketable securities:	158,837,000	210,986,000
Commercial paper | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:	0	0
Marketable securities:	0
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:	2,003,000
Marketable securities:	14,459,000	33,460,000
Corporate debt securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:	0
Marketable securities:	0	0
Corporate debt securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:	2,003,000
Marketable securities:	14,459,000	33,460,000
Corporate debt securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:	0
Marketable securities:	0	0
U.S. Treasuries
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities:	15,511,000	43,050,000
U.S. Treasuries | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities:	0	0
U.S. Treasuries | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities:	15,511,000	43,050,000
U.S. Treasuries | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities:	0
Certificate of deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:		1,000,000
Marketable securities:	41,874,000	44,480,000
Certificate of deposits | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:		0
Marketable securities:	0	0
Certificate of deposits | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:		1,000,000
Marketable securities:	41,874,000	44,480,000
Certificate of deposits | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:		0
Marketable securities:	0
U.S. Government-sponsored enterprises debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities:	6,205,000	6,217,000
U.S. Government-sponsored enterprises debt securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities:	0	0
U.S. Government-sponsored enterprises debt securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities:	6,205,000	6,217,000
U.S. Government-sponsored enterprises debt securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities:	0
ZX008
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Potential contingent consideration payment, maximum	$ 40,500,000

Fair Value Measurements - Recon

Fair Value Measurements - Reconciliation of Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Details) - Contingent consideration - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 39,000	$ 53,100	$ 42,400	$ 63,800
Change in fair value	400	1,800	1,500	6,100
Settlements	$ 0	0	$ (4,500)	(15,000)
Balance at end of period		$ 54,900		$ 54,900

Fair Value Measurements - Signi

Fair Value Measurements - Significant Inputs Used in Fair Value Measurement (Details) $ in Thousands	Sep. 30, 2021USD ($)	Jun. 30, 2021USD ($)	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Dec. 31, 2019USD ($)
Contingent Purchase Consideration
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 39,400		$ 42,400
Fair value		$ 39,000	42,400	$ 54,900	$ 53,100	$ 63,800
Initial Notes | Convertible Notes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of convertible notes	227,000		260,500
Level 3 | Contingent Purchase Consideration
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	39,400		$ 42,400
Discounted cash flow | Contingent Purchase Consideration
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 39,400
Discount rate | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input (percent)	0
Discount rate | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input (percent)	0.020
Discount rate | Weighted average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input (percent)	10
Probability of payment | Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input (percent)	1,000
Probability of payment | Discounted cash flow | Weighted average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input (percent)	1,000

Intangible Asset - Schedule of

Intangible Asset - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Finite-lived intangible asset	$ 102,500	$ 102,500
Accumulated amortization	(9,856)	(3,942)
Total intangible asset, net	$ 92,644	$ 98,558

Intangible Asset - Estimated Am

Intangible Asset - Estimated Amortization Expense (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Estimated useful life of intangible asset	11 years 9 months 18 days	12 years 6 months
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Succeeding year 1	$ 7.9
Succeeding year 2	7.9
Succeeding year 3	7.9
Succeeding year 4	7.9
Succeeding year 5	$ 7.9

Balance Sheet Details - Compone

Balance Sheet Details - Components of Inventory (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Raw materials	$ 1,011	$ 391
Work in process	1,299	243
Finished goods	1,192	392
Total	$ 3,502	$ 1,026

Balance Sheet Details - Details

Balance Sheet Details - Details of Accrued and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Accrued clinical trial expenses	$ 13,272	$ 16,477
Accrued compensation	12,243	10,917
Accrued milestone payment	0	15,000
Other accrued liabilities	20,596	12,570
Total	$ 46,111	$ 54,964

Convertible Senior Notes (Detai

Convertible Senior Notes (Details)	2 Months Ended	3 Months Ended		9 Months Ended
	Oct. 31, 2020USD ($)day$ / shares	Sep. 30, 2021USD ($)$ / shares	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)$ / shares	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Net proceeds from issuance of convertible senior notes				$ 0	$ 194,000,000
Equity component of convertible senior notes			$ 65,482,000
Stock price (in usd per share) | $ / shares		$ 15.19		$ 15.19
The Notes | Convertible Notes
Debt Instrument [Line Items]
Aggregate principal amount	$ 230,000,000
Stated interest rate (percent)	2.75%
Net proceeds from issuance of convertible senior notes	$ 222,500,000
Conversion ratio				0.0411794
Conversion price (in usd per share) | $ / shares	$ 24.28
Multiples of principle amount available as optional conversion to holders	$ 1,000
Liability component allocation of issuance	152,100,000
Carrying amount of equity component	77,900,000
Issuance costs incurred	7,500,000
Debt issuance costs attributable to the liability component	4,900,000
Debt issuance costs attributable to the equity component	2,600,000
Equity component of convertible senior notes	$ 75,300,000
Effective interest rate (percent)		9.90%		9.90%
Unamortized debt discount and issuance costs		$ 74,129,000		$ 74,129,000		$ 80,647,000
Amortization period of unamortized issuance costs				6 years
Total interest expense		3,819,000		$ 11,295,000
Borrowings		$ 155,871,000		$ 155,871,000		$ 149,353,000
The Notes | Convertible Notes | Conversion circumstance, one
Debt Instrument [Line Items]
Conversion price threshold (percent)	130.00%
Conversion threshold in days | day	20
Conversion threshold in consecutive days | day	30
The Notes | Convertible Notes | Conversion circumstance, two
Debt Instrument [Line Items]
Conversion price threshold (percent)	98.00%
Conversion threshold in days | day	5
Conversion threshold in consecutive days | day	10
The Notes | Convertible Notes | Conversion circumstance, three
Debt Instrument [Line Items]
Conversion price threshold (percent)	130.00%	130.00%
Conversion threshold in days | day	20
Conversion threshold in consecutive days | day	30
Redemption price percentage of principal (percent)	100.00%

Convertible Senior Notes - Sche

Convertible Senior Notes - Schedule of Convertible Debt (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Debt Instrument [Line Items]
Amortization of debt discount and issuance costs		$ 6,518	$ 0
The Notes | Convertible Notes
Debt Instrument [Line Items]
Principal amount of Notes	$ 230,000	230,000		$ 230,000
Less: unamortized debt discount and issuance costs	(74,129)	(74,129)		(80,647)
Net carrying amount of Notes	155,871	155,871		149,353
Equity component — net carrying amount	75,333	75,333		$ 75,333
Contractual coupon interest	1,581	4,777
Amortization of debt discount and issuance costs	2,238	6,518
Total interest expense	$ 3,819	$ 11,295

Common Stock and Stock-Based _3

Common Stock and Stock-Based Compensation - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	May 31, 2021	Apr. 30, 2021	Dec. 31, 2020	May 22, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock authorized (shares)	200,000,000	200,000,000	200,000,000	100,000,000	100,000,000
Shares reserved and available for future issuance (shares)	7,100,000	7,100,000			3,900,000
Stock-based compensation capitalized	$ 1	$ 1
2010 Equity Incentive Award Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of common stock that may be issued (shares)			16,000,000			11,500,000
2021 Employment Inducement Equity Incentive Award Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved and available for future issuance (shares)	1,000,000	1,000,000
PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSUs granted (in shares)		494,000

Common Stock and Stock-Based _4

Common Stock and Stock-Based Compensation - Options Activity (Details) shares in Thousands	9 Months Ended
	Sep. 30, 2021$ / sharesshares
Shares (in thousands)
Options outstanding, beginning of period (in shares) | shares	5,311
Granted (in shares) | shares	1,625
Exercised (in shares) | shares	(50)
Canceled (in shares) | shares	(330)
Options outstanding, end of period (in shares) | shares	6,556
Weighted- Average Exercise Price per Share
Outstanding weighted average exercise price, beginning balance (in usd per share) | $ / shares	$ 29.12
Granted weighted average exercise price (in usd per share) | $ / shares	18.21
Exercised weighted average exercise price (in usd per share) | $ / shares	9.77
Canceled weighted average exercise price (in usd per share) | $ / shares	28.73
Outstanding weighted average exercise price, ending balance (in usd per share) | $ / shares	$ 26.58

Common Stock and Stock-Based _5

Common Stock and Stock-Based Compensation - Restricted Stock Unit Activity (Details) shares in Thousands	9 Months Ended
	Sep. 30, 2021$ / sharesshares
RSUs
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of period (in shares)	393
Granted (in shares)	533
Vested (in shares)	(144)
Canceled (in shares)	(47)
Outstanding at end of period (in shares)	735
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Granted - Weighted average fair value per share at grant date (in usd per share) | $ / shares	$ 18.11
PSUs
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of period (in shares)	0
Granted (in shares)	494
Vested (in shares)	0
Canceled (in shares)	(36)
Outstanding at end of period (in shares)	458
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Granted - Weighted average fair value per share at grant date (in usd per share) | $ / shares	$ 19.53
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of period (in shares)	393
Granted (in shares)	1,027
Vested (in shares)	(144)
Canceled (in shares)	(83)
Outstanding at end of period (in shares)	1,193
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Granted - Weighted average fair value per share at grant date (in usd per share) | $ / shares	$ 18.79

Common Stock and Stock-Based _6

Common Stock and Stock-Based Compensation - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 8,152	$ 7,141	$ 25,776	$ 21,838
Time-based stock options and RSUs
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	6,962	5,507	23,171	19,923
Performance-based stock units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	1,066	1,441	2,120	1,441
Employee stock purchase plan (ESPP)
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	124	193	485	474
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	2,905	2,865	10,729	9,082
Selling, general and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 5,247	$ 4,276	$ 15,047	$ 12,756

Net Loss Per Share - Reconcilia

Net Loss Per Share - Reconciliation of Numerator and Denominators in Computing Net Loss per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net loss	$ (58,004)	$ (58,896)	$ (55,630)	$ (60,089)	$ (53,324)	$ (25,800)	$ (172,530)	$ (139,213)
Denominator:
Shares used in basic net loss per share calculation (in shares)	55,905			55,548			55,831	53,039
Shares used in diluted net loss per share calculation (in shares)	55,905			55,548			55,831	53,039
Net loss per share, basic (in dollars per share)	$ (1.04)			$ (1.08)			$ (3.09)	$ (2.62)
Net loss per share, diluted (in dollars per share)	$ (1.04)			$ (1.08)			$ (3.09)	$ (2.62)

Net Loss Per Share - Antidiluti

Net Loss Per Share - Antidilutive Securities (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share amount	17,143	5,868	16,601	5,453
Shares subject to outstanding stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share amount	6,534	5,149	6,118	4,848
Shares subject to outstanding restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share amount	1,173	422	1,032	487
Shares subject to outstanding warrants to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share amount	6	28	21	28
Shares issuable upon conversion of Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share amount	9,430	269	9,430	90

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Provision (benefit) for income taxes	$ 0	$ 0	$ 0	$ (17,425)

United Kingdom (U.K.) Researc_2

United Kingdom (U.K.) Research and Development (R&D) Tax Relief Scheme (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	9 Months Ended
	Dec. 31, 2019	Mar. 31, 2020	Sep. 30, 2021
U.K. tax legislation | U.K. tax legislation
Operating Loss Carryforwards [Line Items]
Window to seek relief under U.K. tax legislature			2 years
Tax year 2017
Operating Loss Carryforwards [Line Items]
Claim for refundable cash credit	$ 9.9
Proceeds from claims	9.9
Tax year 2018
Operating Loss Carryforwards [Line Items]
Claim for refundable cash credit	9.8
Proceeds from claims	$ 9.8
2017 and 2018 tax year claims
Operating Loss Carryforwards [Line Items]
Other income		$ 19.7

Litigation (Details)

Litigation (Details) - patent	Oct. 28, 2021	Oct. 06, 2021	Aug. 30, 2021
Apotex Inc. and Apotex Corp.
Loss Contingencies [Line Items]
Number of patents allegedly infringed			2
Subsequent event | Apotex Inc. and Apotex Corp.
Loss Contingencies [Line Items]
Number of patents allegedly infringed	2
Subsequent event | Lupin Limited (“Lupin”)
Loss Contingencies [Line Items]
Number of patents allegedly infringed		7