0001564590-21-007841 | 10-K | XBRL Viewer | Heron Therapeutics INC DE

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
Document and Entity Information - USD ($) $ in Billions	Dec. 31, 2020	Feb. 05, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Trading Symbol	HRTX
Entity Registrant Name	HERON THERAPEUTICS, INC. /DE/
Entity Central Index Key	0000818033
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Entity Common Stock, Shares Outstanding		91,396,509
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity File Number	001-33221
Entity Tax Identification Number	94-2875566
Entity Address, Address Line One	4242 CAMPUS POINT COURT
Entity Address, Address Line Two	SUITE 200
Entity Address, City or Town	SAN DIEGO
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92121
City Area Code	858
Local Phone Number	251-4400
Entity Interactive Data Current	Yes
Entity Incorporation, State or Country Code	DE
Document Annual Report	true
Entity Public Float			$ 1.3
Document Transition Report	false
Title of 12(b) Security	Common Stock, par value $0.01 per share
Security Exchange Name	NASDAQ
Documents Incorporated by Reference	Portions of the registrant’s Definitive Proxy Statement related to its 2021 Annual Meeting of Stockholders’ to be held on or about June 17, 2021 are incorporated by reference into Part III of this Annual Report on Form 10-K. Such Definitive Proxy Statement will be filed with the U.S. Securities and Exchange Commission within 120 days after the end of the fiscal year to which this report relates. Except as expressly incorporated by reference, the registrant’s Definitive Proxy Statement shall not be deemed to be part of this report.

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 105,138	$ 71,898
Short-term investments	103,353	319,074
Accounts receivable, net	41,850	39,879
Inventory	41,905	24,968
Prepaid expenses and other current assets	21,950	23,245
Total current assets	314,196	479,064
Property and equipment, net	22,737	19,618
Right-of-use lease assets	16,277	13,754
Other assets	346	346
Total assets	353,556	512,782
Current liabilities:
Accounts payable	525	2,758
Accrued clinical and manufacturing liabilities	49,962	34,614
Accrued payroll and employee liabilities	13,597	15,248
Other accrued liabilities	28,369	36,535
Current lease liabilities	2,997	1,926
Convertible notes payable to related parties, net of discount	7,053	5,624
Total current liabilities	102,503	96,705
Non-current lease liabilities	14,561	12,242
Total liabilities	117,064	108,947
Commitments and contingencies (see Note 6)
Stockholders’ equity:
Preferred stock, $0.01 par value: 2,500 shares authorized; no shares issued or outstanding at December 31, 2020 and 2019
Common stock, $0.01 par value: 150,000 shares authorized; 91,310 and 90,304 shares issued and outstanding at December 31, 2020 and 2019, respectively	913	903
Additional paid-in capital	1,628,070	1,568,317
Accumulated other comprehensive income	257	85
Accumulated deficit	(1,392,748)	(1,165,470)
Total stockholders’ equity	236,492	403,835
Total liabilities and stockholders’ equity	$ 353,556	$ 512,782

Consolidated Balance Sheets (Parenthetical) - $ / shares shares in Thousands	Dec. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	2,500	2,500
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	150,000	150,000
Common stock, shares issued (in shares)	91,310	90,304
Common stock, shares outstanding (in shares)	91,310	90,304

Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues:
Net product sales	$ 88,638	$ 145,968	$ 77,474
Operating expenses:
Cost of product sales	36,189	61,619	27,512
Research and development	174,533	167,382	140,032
General and administrative	42,226	37,897	29,263
Sales and marketing	63,853	89,764	64,604
Total operating expenses	316,801	356,662	261,411
Loss from operations	(228,163)	(210,694)	(183,937)
Other income, net:
Interest income	3,633	7,259	5,965
Interest expense	(1,901)	(1,472)	(2,672)
Other income (expense)	(847)	158	1,804
Total other income, net	885	5,945	5,097
Net loss	(227,278)	(204,749)	(178,840)
Other comprehensive income (loss):
Unrealized gains (losses) on short-term investments	172	172	(77)
Comprehensive loss	$ (227,106)	$ (204,577)	$ (178,917)
Basic and diluted net loss per share	$ (2.50)	$ (2.50)	$ (2.44)
Shares used in computing basic and diluted net loss per share	90,774	81,779	73,193

Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative Effect Period of Adoption Adjustment	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit	Accumulated Deficit Cumulative Effect Period of Adoption Adjustment
Balance at Dec. 31, 2017	$ 131,136	$ 1,574	$ 646	$ 913,955	$ (10)	$ (783,455)	$ 1,574
Balance (in shares) at Dec. 31, 2017			64,609
Issuance of common stock in public offerings, net	363,128		$ 120	363,008
Issuance of common stock in public offerings, net (in shares)			11,963
Conversion benefit included in Convertible Notes issued	392			392
Issuance of common stock under Employee Stock Purchase Plan	1,179		$ 1	1,178
Issuance of common stock under Employee Stock Purchase Plan (in shares)			72
Issuance of common stock on exercise of stock options	18,301		$ 15	18,286
Issuance of common stock on exercise of stock options (in shares)			1,530
Stock-based compensation expense	33,367			33,367
Net loss	(178,840)					(178,840)
Net unrealized gain (loss) on short-term investments	(77)				(77)
Comprehensive loss	(178,917)
Balance at Dec. 31, 2018	370,160		$ 782	1,330,186	(87)	(960,721)
Balance (in shares) at Dec. 31, 2018			78,174
Issuance of common stock in public offerings, net	162,151		$ 99	162,052
Issuance of common stock in public offerings, net (in shares)			9,857
Conversion benefit included in Convertible Notes issued	416			416
Issuance of common stock under Employee Stock Purchase Plan	2,109		$ 1	2,108
Issuance of common stock under Employee Stock Purchase Plan (in shares)			126
Issuance of common stock on exercise of stock options	22,164		$ 20	22,144
Issuance of common stock on exercise of stock options (in shares)			1,983
Issuance of common stock on exercise of warrants	1		$ 1
Issuance of common stock on exercise of warrants (in shares)			132
Issuance of common stock on conversion of convertible notes (in shares)			32
Stock-based compensation expense	51,411			51,411
Net loss	(204,749)					(204,749)
Net unrealized gain (loss) on short-term investments	172				172
Comprehensive loss	(204,577)
Balance at Dec. 31, 2019	403,835		$ 903	1,568,317	85	(1,165,470)
Balance (in shares) at Dec. 31, 2019			90,304
Conversion benefit included in Convertible Notes issued	440			440
Issuance of common stock under Employee Stock Purchase Plan	2,317		$ 2	2,315
Issuance of common stock under Employee Stock Purchase Plan (in shares)			194
Issuance of common stock on exercise of stock options	6,759		$ 5	6,754
Issuance of common stock on exercise of stock options (in shares)			545
Issuance of common stock on exercise of warrants	3		$ 3
Issuance of common stock on exercise of warrants (in shares)			267
Issuance of common stock on conversion of Convertible Notes	26			26
Stock-based compensation expense	50,218			50,218
Net loss	(227,278)					(227,278)
Net unrealized gain (loss) on short-term investments	172				172
Comprehensive loss	(227,106)
Balance at Dec. 31, 2020	$ 236,492		$ 913	$ 1,628,070	$ 257	$ (1,392,748)
Balance (in shares) at Dec. 31, 2020			91,310

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
Consolidated Statements of Cash Flows - USD ($)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating activities:
Net loss	$ (227,278,000)	$ (204,749,000)	$ (178,840,000)
Adjustments to reconcile net loss to net cash used for operating activities:
Stock-based compensation expense	50,218,000	51,411,000	33,367,000
Depreciation and amortization	2,847,000	2,044,000	1,513,000
Amortization of debt discount	1,429,000	1,050,000	890,000
Amortization of premium (accretion of discount) on short-term investments	125,000	(3,730,000)	(3,412,000)
Realized gain on available-for-sale investments	0	(8,000)	0
Impairment of property and equipment	847,000	107,000	72,000
Loss on disposal of property and equipment		62,000	29,000
Change in operating assets and liabilities:
Accounts receivable	(1,971,000)	24,773,000	(22,778,000)
Inventory	(16,937,000)	14,064,000	(29,122,000)
Prepaid expenses and other assets	1,295,000	(12,052,000)	(7,482,000)
Accounts payable	(2,233,000)	(14,105,000)	(1,906,000)
Accrued clinical and manufacturing liabilities	15,348,000	10,144,000	(3,614,000)
Accrued payroll and employee liabilities	(1,651,000)	1,851,000	4,537,000
Other accrued liabilities	(6,859,000)	4,558,000	14,941,000
Net cash used for operating activities	(184,820,000)	(124,580,000)	(191,805,000)
Investing activities:
Purchases of short-term investments	(134,007,000)	(477,035,000)	(497,104,000)
Maturities and sales of short-term investments	349,775,000	462,406,000	227,700,000
Purchases of property and equipment	(6,813,000)	(7,154,000)	(9,171,000)
Proceeds from the sale of property and equipment			25,000
Net cash provided by (used for) investing activities	208,955,000	(21,783,000)	(278,550,000)
Financing activities:
Net proceeds from sale of common stock and/or pre-funded warrants		162,151,000	363,128,000
Proceeds from purchases under the Employee Stock Purchase Plan	2,317,000	2,109,000	1,179,000
Proceeds from stock option exercises	6,759,000	22,164,000	18,301,000
Proceeds from conversion of convertible notes payable	26,000
Proceeds from warrant exercises	3,000	1,000
Repayment of promissory note payable to related party			(25,000,000)
Net cash provided by financing activities	9,105,000	186,425,000	357,608,000
Net increase (decrease) in cash and cash equivalents	33,240,000	40,062,000	(112,747,000)
Cash and cash equivalents at beginning of year	71,898,000	31,836,000	144,583,000
Cash and cash equivalents at end of year	$ 105,138,000	$ 71,898,000	31,836,000
Supplemental disclosure of cash flow information:
Interest paid			1,183,000
Cumulative effect of adoption of new accounting standard			$ 1,574,000

Organization and Business

12 Months Ended

Dec. 31, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Organization and Business

1.	Organization and Business

Heron Therapeutics, Inc. (“Company,” “Heron” or “we”) is a commercial-stage biotechnology company focused on improving the lives of patients by developing best-in-class treatments to address some of the most important unmet patient needs. We are developing novel, patient-focused solutions that apply our innovative science and technologies to already-approved pharmacological agents for patients suffering from pain or cancer.

In August 2016, our first commercial product, SUSTOL^® (granisetron) extended-release injection (“SUSTOL”), was approved by the U.S. Food and Drug Administration (“FDA”). SUSTOL is indicated in combination with other antiemetics in adults for the prevention of acute and delayed nausea and vomiting associated with initial and repeat courses of moderately emetogenic chemotherapy (MEC) or anthracycline and cyclophosphamide (AC) combination chemotherapy regimens. SUSTOL is an extended-release, injectable 5-hydroxytryptamine type 3 (“5-HT₃”) receptor antagonist that utilizes our proprietary Biochronomer^® drug delivery technology to maintain therapeutic levels of granisetron for ≥5 days. We commenced commercial sales of SUSTOL in the U.S. in October 2016.

In November 2017, our second commercial product, CINVANTI^® (aprepitant) injectable emulsion (“CINVANTI”) was approved by the FDA. In October 2019, the FDA approved our supplemental New Drug Application (“sNDA”) for CINVANTI to expand the indication and recommended dosage to include the 130 mg single-dose regimen for patients receiving moderately emetogenic cancer chemotherapy (“MEC”). CINVANTI, in combination with other antiemetic agents, is indicated in adults for the prevention of acute and delayed nausea and vomiting associated with initial and repeat courses of highly emetogenic cancer chemotherapy (HEC) including high-dose cisplatin as a single-dose regimen, delayed nausea and vomiting associated with initial and repeat courses of moderately emetogenic cancer chemotherapy (MEC) as a single-dose regimen, and nausea and vomiting associated with initial and repeat courses of MEC as a 3-day regimen. CINVANTI is an intravenous (“IV”) formulation of aprepitant, a substance P/neurokinin-1 (“NK₁”) receptor antagonist. We commenced commercial sales of CINVANTI in the U.S. in January 2018. In February 2019, the FDA approved our sNDA for CINVANTI, for IV use, which expanded the administration of CINVANTI beyond the initially approved administration method (a 30-minute IV infusion) to include a 2-minute IV injection.

HTX-019 is an investigational agent for the prevention of postoperative nausea and vomiting (“PONV”). HTX-019 is an IV injectable emulsion formulation designed to directly deliver aprepitant, the active ingredient in EMEND^® (aprepitant) capsules, which is the only NK₁ receptor antagonist approved in the U.S. for the prevention of PONV in adults. The FDA-approved dose of oral EMEND is 40 mg for PONV, which is given within 3 hours prior to induction of anesthesia for surgery. An Investigational New Drug application for HTX-019 for PONV was approved by the FDA in late September 2020. In a Phase 1 clinical trial, 32 mg of HTX-019 as a 30-second IV injection was demonstrated to be bioequivalent to oral aprepitant 40 mg. An NDA for HTX-019 is planned in late 2021 for prevention of PONV in adults.

In September 2020, our third approved product, ZYNRELEF^™ (also known as HTX-011) was granted a marketing authorization by the European Commission (“EC”). ZYNRELEF is indicated for the treatment of somatic postoperative pain from small- to medium-sized surgical wounds in adults. ZYNRELEF, a non-opioid, is a dual-acting, fixed-dose combination of the local anesthetic bupivacaine with a low dose of the nonsteroidal anti-inflammatory drug meloxicam. It is the first and only extended-release local anesthetic to demonstrate in Phase 3 studies significantly reduced pain and opioid use through 72 hours compared to bupivacaine solution, the current standard-of-care local anesthetic for postoperative pain control. As we build large-scale manufacturing capacity to meet the anticipated commercial demand in the U.S. and the rest of the world, we are developing a coordinated global marketing strategy.

HTX-011 (ZYNRELEF in Europe) is an investigational agent in the United States and Canada. The FDA granted Breakthrough Therapy designation to HTX-011 and the New Drug Application (“NDA”) received Priority Review designation. A Complete Response Letter (“CRL”) was received from the FDA regarding the NDA for HTX-011 in June 2020. The CRL stated that the FDA is unable to approve the NDA in its present form based on the need for additional non-clinical information. Based on the complete review of the NDA, the FDA did not identify any clinical safety or efficacy issues or chemistry, manufacturing and controls issues. There are four non-clinical issues in the CRL, none of which relate to any observed toxicity. Three relate to confirming exposure of excipients in preclinical reproductive toxicology studies, and the fourth relates to changing the manufacturing release specification of the allowable level of an impurity based on animal toxicology coverage. At the Type A End-of-Review meeting in September 2020 (the “Type A Meeting”), the FDA agreed with the change to the manufacturing specification proposed by Heron to address the FDA’s concern and agreed with our proposal to bridge the clinical and nonclinical excipient exposure data to address the other 3 deficiencies. In November 2020, we resubmitted the NDA to the FDA for HTX-011 based on the outcome and final minutes of the Type A Meeting. The Prescription Drug User Fee Act goal date is May 12, 2021. Our New Drug Submission for HTX-011 for the management of postoperative pain was accepted by Health Canada in November 2019. We are working to respond to a list of questions received from Health Canada in July 2020, and we anticipate up to a 300-day review period following our responsive submission.

HTX-034, our next-generation product candidate for postoperative pain management, is an investigational non-opioid, fixed-dose combination, extended‑release solution of the local anesthetic bupivacaine, the nonsteroidal anti-inflammatory drug meloxicam and an additional agent that further potentiates the activity of bupivacaine. HTX-034 is formulated in the same proprietary polymer as HTX-011 (ZYNRELEF in the Europe). By combining two different mechanisms that each enhance the activity of the local anesthetic bupivacaine, HTX-034 is designed to provide superior and prolonged analgesia. Local administration of HTX-034 in a validated preclinical postoperative pain model resulted in sustained analgesia for 7 days. In May 2020, we initiated a Phase 1b/2 clinical study in patients undergoing bunionectomy of HTX-034. In the Phase 1b portion of this Phase 1b/2 double-blind, randomized, active-controlled, dose-escalation study in 33 patients undergoing bunionectomy, the reduction in pain intensity observed was greater with the lowest dose of HTX-034 evaluated (containing 21.7 mg of bupivacaine plus meloxicam and aprepitant) than with the bupivacaine 50 mg solution through 96 hours. In addition, 45.5% of HTX-034 patients remained opioid-free through Day 15 with median opioid consumption of 2.5 milligram morphine equivalents (same as one 5 mg oxycodone pill) through 72-hours, a 71% reduction compared to bupivacaine solution. We expect to initiate the expanded Phase 2 portion of the study for HTX-034 in the first quarter of 2021.

As of December 31, 2020, we had $208.5 million in cash, cash equivalents and short-term investments. We have incurred significant operating losses and negative cash flows from operations. Management believes that the Company’s existing cash, cash equivalents and short-term investments will be sufficient to meet the Company’s anticipated cash requirements for at least one year from the date this Annual Report on Form 10-K is filed with the U.S. Securities and Exchange Commission (“SEC”).

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2.	Summary of Significant Accounting Policies

Principles of Consolidation

The accompanying consolidated financial statements include the accounts of Heron Therapeutics, Inc. and its wholly-owned subsidiary, Heron Therapeutics B.V., which was organized in the Netherlands in March 2015. Heron

Therapeutics B.V. has no operations and no material assets or liabilities, and there have been no significant transactions related to Heron Therapeutics B.V. since its inception.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the U.S. (“GAAP”) requires management to make estimates and assumptions that affect the amounts reported in the financial statements and disclosures made in the accompanying notes to the financial statements. Our significant accounting policies that involve significant judgment and estimates include revenue recognition, investments, inventory and the related reserves, accrued clinical liabilities, income taxes and stock-based compensation. Actual results could differ materially from those estimates.

Cash, Cash Equivalents and Short-term Investments

Cash and cash equivalents consist of cash and highly liquid investments with contractual maturities of three months or less from the original purchase date.

Short-term investments consist of securities with contractual maturities of greater than three months from the original purchase date. Securities with contractual maturities greater than one year are classified as short-term investments on the consolidated balance sheets, as we have the ability, if necessary, to liquidate these securities to meet our liquidity needs in the next 12 months. We have classified our short-term investments as available-for-sale securities in the accompanying consolidated financial statements. Available-for-sale securities are stated at fair market value, with net changes in unrealized gains and losses reported in other comprehensive loss and realized gains and losses included in other income (expense), net. The cost of securities sold is based on the specific identification method. Interest and dividends on securities classified as available-for-sale are included in interest income.

Our bank and investment accounts have been placed under control agreements in accordance with our Senior Secured Convertible Notes (“Convertible Notes”) (see Note 8).

Fair Value of Financial Instruments

A company may elect to use fair value to measure accounts and loans receivable, available-for-sale and held-to-maturity securities, equity method investments, accounts payable, guarantees and issued debt. Other eligible items include firm commitments for financial instruments that otherwise would not be recognized at inception and non-cash warranty obligations where a warrantor is permitted to pay a third party to provide the warranty goods or services. If the use of fair value is elected, any upfront costs and fees related to the item such as debt issuance costs must be recognized in earnings and cannot be deferred. The fair value election is irrevocable and generally made on an instrument-by-instrument basis, even if a company has similar instruments that it elects not to measure based on fair value. Unrealized gains and losses on existing items for which fair value has been elected are reported as a cumulative adjustment to beginning retained earnings and any changes in fair value are recognized in earnings. We have elected to not apply the fair value option to our financial assets and liabilities.

Financial instruments, including cash and cash equivalents, receivables, inventory, prepaid expenses, other current assets, accounts payable and accrued expenses, are carried at cost, which is considered to be representative of their respective fair values because of the short-term maturity of these instruments. Short-term available-for-sale investments are carried at fair value (see Note 3). Our Convertible Notes outstanding at December 31, 2020 do not have a readily available ascertainable market value, however, the carrying value is considered to approximate its fair value.

Concentration of Credit Risk

Cash, cash equivalents and short-term investments are financial instruments that potentially subject us to concentrations of credit risk. We deposit our cash in financial institutions. At times, such deposits may be in excess of insured limits. We may also invest our excess cash in money market funds, U.S. government and agencies,

corporate debt securities and commercial paper. We have established guidelines relative to our diversification of our cash investments and their maturities in an effort to maintain safety and liquidity. These guidelines are periodically reviewed and modified to take advantage of trends in yields and interest rates.

CINVANTI and SUSTOL are distributed in the U.S. through a limited number of specialty distributors and full line wholesalers (collectively, “Customers”) that resell to healthcare providers and hospitals, the end users of CINVANTI and SUSTOL.

The following table includes the percentage of net product sales and accounts receivable balances for our three major Customers, each of which comprised 10% or more of our net product sales:

	Net Product Sales			Accounts Receivable
	Year Ended December 31, 2020			As of December 31, 2020
Customer A		44.0	%		61.3	%
Customer B		33.5	%		29.8	%
Customer C		20.8	%		8.5	%
Total		98.3	%		99.6	%

Accounts Receivable, Net

Accounts receivable are recorded at the invoice amount, net of an allowance for doubtful accounts. The allowance for doubtful accounts reflects accounts receivable balances that are believed to be uncollectible. In estimating the allowance for doubtful accounts, we consider: (1) our historical experience with collections and write-offs; (2) the credit quality of our Customers and any recent or anticipated changes thereto; and (3) the outstanding balances and past due amounts from our Customers.

We offered extended payment terms to our Customers in connection with our product launches of SUSTOL and CINVANTI in October 2016 and January 2018, respectively, in anticipation of the timing in reimbursement by government and commercial payers. Effective January 2018, we shortened payment terms to certain of our SUSTOL Customers. Effective January 2019, we shortened payment terms to our CINVANTI Customers. As of December 31, 2020, extended payment terms given to our Customers were evaluated in accordance with GAAP and did not impact the collectability of accounts receivables.

As of December 31, 2020 and 2019, we determined that an allowance for doubtful accounts was not required. For the years ended December 31, 2020 and 2019, we did not write-off any accounts receivable balances.

Inventory

Inventory is stated at the lower of cost or estimated net realizable value on a first-in, first-out, or FIFO, basis. We periodically analyze our inventory levels and write down inventory that has become obsolete, inventory that has a cost basis in excess of its estimated realizable value and inventory quantities that are in excess of expected sales requirements as cost of product sales. The determination of whether inventory costs will be realizable requires estimates by management. If actual market conditions are less favorable than projected by management, additional write-downs of inventory may be required, which would be recorded as cost of product sales.

Property and Equipment

Property and equipment is stated at cost less accumulated depreciation and amortization. Depreciation is calculated on a straight-line basis over the estimated useful lives of the assets (generally 5 years). Leasehold

improvements are stated at cost and amortized on a straight-line basis over the shorter of the estimated useful life of the asset or the lease term.

Impairment of Long-Lived Assets

If indicators of impairment exist, we assess the recoverability of the affected long-lived assets by determining whether the carrying value of such assets can be recovered through undiscounted future operating cash flows. If impairment is indicated, we measure the amount of such impairment by comparing the carrying value of the asset to the fair value of the asset and record the impairment as a reduction in the carrying value of the related asset with a corresponding charge to operating expenses. Estimating the undiscounted future operating cash flows associated with long-lived assets requires judgment and assumptions that could differ materially from actual results.

Leases

In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-02, Leases (Topic 842) (“ASU 2016-02”), which provides principles for the recognition, measurement, presentation and disclosure of leases for both lessees and lessors. In July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842): Targeted Improvements and ASU No. 2018-10, Codification Improvements to Topic 842, Leases. ASU 2016-02 and the subsequent modifications are identified as the FASB Accounting Standards Codification (“ASC”) Topic 842 (“Topic 842”). Topic 842 requires lessees to classify leases as either finance or operating based on whether or not the lease is effectively a financed purchase. Lease expense is recognized over the term of the lease using an effective interest method for finance leases and on a straight-line basis over the lease term for operating leases. A lessee is also required to record a right-of-use (“ROU”) lease asset and a lease liability for all leases with a lease term greater than 12 months. Leases with a term of 12 months or less will be accounted for similar to historical guidance for operating leases under the FASB ASC Topic 840, Leases. We adopted Topic 842 on January 1, 2019 using the alternative transition method allowed under ASU No. 2018-11. We elected the package of practical expedients permitted under the transition guidance, which allowed us to carryforward our historical assessments of: (i) whether a contract is or contains a lease; (ii) lease classification; and (iii) initial direct costs. We elected a policy of not recording leases on the balance sheet when the lease term is 12 months or less. The adoption of Topic 842 had a substantial impact on the consolidated balance sheet with the recognition of lease liabilities and corresponding ROU lease assets. There was no material impact on our results of operations or liquidity (see Note 6).

We determine if an agreement is a lease or contains lease components at inception. Operating leases are recorded as lease liabilities with corresponding ROU lease assets on the consolidated balance sheets. ROU lease assets represent our right to use the underlying assets over the lease term, and lease liabilities represent the present value of our obligation to make lease payments arising from the lease. Lease liabilities are recognized at the lease commencement based on the present value of lease payments over the lease term. As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. We use the implicit rate when readily determinable. The ROU lease assets equal the lease liabilities, less unamortized lease incentives, unamortized initial direct costs and the cumulative difference between rent expense and amounts paid under the lease. The lease term includes any option to extend or terminate the lease when it is reasonably certain that we will exercise that option. Lease expense is recognized on a straight-line basis over the lease term. We have lease agreements with both lease and non-lease components, which are generally accounted for separately.

Revenue Recognition

In May 2014, FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (“Topic 606”). Topic 606 is based on the principle that revenue should be recognized to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In the first quarter of 2018, we adopted Topic 606 using the modified retrospective approach. Under this approach, incremental disclosures are provided to present each financial statement line item for 2018 under the prior standard. As a result of the adoption of Topic 606, we recorded a cumulative adjustment to accumulated deficit of $1.6 million on January 1, 2018. This adjustment reflects the acceleration of $2.9 million in gross product sales less $1.1 million in product sales allowances and $0.2 million in cost of product sales (see Note 5).

Accrued Clinical Liabilities

We accrue clinical costs based on work performed, which relies on estimates of the progress of the trials and the related expenses incurred. Clinical trial related contracts vary significantly in duration, and may be for a fixed amount, based on the achievement of certain contingent events or deliverables, a variable amount based on actual costs incurred, capped at a certain limit or contain a combination of these elements. Revisions are recorded to research and development expense in the period in which the facts that give rise to the revision become known. Historically, revisions have not resulted in material changes to research and development expense; however, a modification in the protocol of a clinical trial or cancellation of a clinical trial could result in a material charge to our results of operations.

Research and Development Expense

All costs of research and development are expensed in the period incurred. Research and development expense primarily consists of personnel and related costs, stock-based compensation expense, fees paid to outside service providers and consultants, facilities costs and materials used in clinical and preclinical trials and research and development.

Patent Costs

We incur outside legal fees in connection with filing and maintaining our various patent applications. All patent costs are expensed as incurred and are included in general and administrative expense in the consolidated statements of operations and comprehensive loss.

Stock-Based Compensation Expense

We estimate the fair value of stock-based payment awards using the Black-Scholes option pricing model. This fair value is then amortized using the straight-line single-option method of attributing the value of stock-based compensation to expense over the requisite service periods of the awards. The Black-Scholes option pricing model requires the input of complex and subjective assumptions, including each option’s expected life and price volatility of the underlying stock.

As stock-based compensation expense is based on awards ultimately expected to vest, it has been reduced for estimated forfeitures. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. Forfeitures are estimated based on historical data.

Warrants

We have issued warrants to purchase shares of our common stock in conjunction with certain equity financings or in exchange for services. The terms of the warrants were evaluated to determine the appropriate classification as equity or a liability.

Income Taxes

We recognize the impact of a tax position in our consolidated financial statements if the position is more likely than not to be sustained on examination and on the technical merits of the position. The total amount of unrecognized tax benefits, if recognized, would affect other tax accounts, primarily deferred taxes in future periods, and would not affect our effective tax rate, since we maintain a full valuation allowance against our deferred tax assets (see Note 10). We recognize interest and penalties related to income tax matters in income tax expense.

Comprehensive Loss

Comprehensive loss is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources. Net changes in unrealized gains and losses on available-for-sale securities are included in other comprehensive income (loss) and represent the difference between our net loss and comprehensive net loss for all periods presented.

Net Loss per Share

Basic net loss per share is calculated by dividing the net loss by the weighted-average number of common shares outstanding for the period, without consideration of common stock equivalents. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common shares and common stock equivalents outstanding for the period determined using the treasury stock method. For purposes of this calculation, stock options, warrants and shares of common stock underlying Convertible Notes are considered to be common stock equivalents and are included in the calculation of diluted net loss per share only when their effect is dilutive.

Because we have incurred a net loss for all periods presented in the consolidated statements of operations and comprehensive loss, the following common stock equivalents were not included in the computation of net loss per share because their effect would be anti-dilutive (in thousands):

	December 31,
	2020		2019		2018
Stock options outstanding		18,912		16,665		15,265
Restricted stock units outstanding		603		—		—
Warrants outstanding		220		508		640
Shares of common stock underlying Convertible Notes outstanding		9,510		8,960		8,473

Recent Accounting Pronouncements

Adopted in 2020

In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820) - Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”), which is designed to improve the effectiveness of disclosures by removing, modifying and adding disclosures related to fair value measurements. In the first quarter of 2020, we adopted the provisions of ASU 2018-13 which did not have a material impact on our financial statement disclosures.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which amends the impairment model by requiring entities to use a forward-looking approach based on expected losses to estimate credit losses on certain types of financial instruments, including trade receivables and available-for-sale debt securities. In May 2019, the FASB issued ASU No. 2019-05, Financial Instruments - Credit Losses (Topic 326): Targeted Transition Relief (“ASU 2019-05”), which amends ASU 2016-13 by providing entities with an option to irrevocably elect the fair value option to be applied on an instrument-by-instrument basis for eligible financial instruments that are within the scope of Topic 326. The fair value option election does not apply to held-to-maturity debt securities. On January 1, 2020, we adopted the provisions of ASU 2016-13, which did not have a material impact on our results of operations, financial condition or internal controls.

Not Yet Adopted

In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740) (“ASU 2019-12”), which is intended to simplify the accounting for income taxes by eliminating certain exceptions related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. ASU 2019-12 also simplifies aspects of the accounting for franchise taxes and enacted changes in tax laws or rates. Adoption of ASU 2019-12 requires certain changes to be made prospectively and other changes to be made retrospectively. On January 1, 2021 we adopted the provisions of ASU 2019-12 which did not have a material impact on our results of operations, cash flows, financial condition, internal controls or related disclosures.

Fair Value Measurements

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

3.	Fair Value Measurements

Fair value is defined as the exchange price that would be received for 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. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The FASB ASC Topic 820, Fair Value Measurements & Disclosures, establishes a fair value hierarchy which prioritizes the inputs used in measuring fair value as follows:

•

Level 1—Observable inputs such as quoted prices in active markets for identical assets or liabilities.

•

Level 2—Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

•

Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

We measure cash, cash equivalents and short-term investments at fair value on a recurring basis. The fair values of these such assets were as follows (in thousands):

	Fair Value Measurements at Reporting Date Using
	Balance at December 31, 2020		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash and money market funds	$	49,149	$	49,149	$	—	$	—
U.S. treasury bills and government agency obligations		20,276		—		20,276		—
U.S. corporate debt securities		11,547		—		11,547		—
Foreign corporate debt securities		15,557		—		15,557		—
U.S. commercial paper		27,996		—		27,996		—
Foreign commercial paper		83,966		—		83,966		—
Total	$	208,491	$	49,149	$	159,342	$	—

	Fair Value Measurements at Reporting Date Using
	Balance at December 31, 2019		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash and money market funds	$	56,931	$	56,931	$	—	$	—
U.S. treasury bills and government agency obligations		140,626		140,626		—		—
U.S. corporate debt securities		80,170		—		80,170		—
Foreign corporate debt securities		23,203		—		23,203		—
U.S. commercial paper		32,801		—		32,801		—
Foreign commercial paper		57,241		—		57,241		—
Total	$	390,972	$	197,557	$	193,415	$	—

We have not transferred any investment securities between the three levels of the fair value hierarchy.

As of December 31, 2020, cash equivalents included $55.9 million of available-for-sale securities with contractual maturities of three months or less and short-term investments included $103.4 million of available-for-sale securities with contractual maturities of three months to one year. As of December 31, 2019, cash equivalents included $15.0 million of available-for-sale securities with contractual maturities of three months or less. As of December 31, 2019, short-term investments included $279.7 million of available-for-sale securities with contractual maturities of three months to one year and $39.4 million of available-for-sale securities with contractual maturities greater than one year. The money market funds as of December 31, 2020 and 2019 are included in cash and cash equivalents on the consolidated balance sheets.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Balance Sheet Details

12 Months Ended

Dec. 31, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Balance Sheet Details

4.	Balance Sheet Details

Short-Term Investments

The following is a summary of our short-term investments (in thousands):

	December 31, 2020
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
U.S. treasury bills and government agency obligations	$	20,110	$	166	$	—	$	20,276
U.S. corporate debt		11,505		42		—		11,547
Foreign corporate debt		15,508		49		—		15,557
U.S. commercial paper		13,997		—		—		13,997
Foreign commercial paper		41,976		—		—		41,976
Total	$	103,096	$	257	$	—	$	103,353

	December 31, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
U.S. treasury bills and government agency obligations	$	140,567	$	59	$	—	$	140,626
U.S. corporate debt securities		80,159		11		—		80,170
Foreign corporate debt securities		23,188		15		—		23,203
U.S. commercial paper		32,801		—		—		32,801
Foreign commercial paper		42,274		—		—		42,274
Total	$	318,989	$	85	$	—	$	319,074

The amortized cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity. We regularly monitor and evaluate the realizable value of our marketable securities. We did not recognize any impairment losses for the years ended December 31, 2020 and 2019.

Unrealized gains and losses associated with our investments are reported in accumulated other comprehensive loss. For both years ended December 31, 2020 and 2019, we recorded $172,000 in net unrealized gains associated with our short-term investments. For the year ended December 31, 2018, we recorded $77,000 in net unrealized losses associated with our short-term investments.

Realized gains and losses associated with our investments, if any, are reported in the statements of operations and comprehensive loss. We recognized $8,000 in realized gains during the year ended December 31, 2019. We did not recognize any realized gains or losses during the years ended December 31, 2020 and 2018.

Inventory

Inventory consists of the following (in thousands):

	December 31,
	2020		2019
Raw materials	$	18,994	$	6,635
Work in process		6,847		12,571
Finished goods		16,064		5,762
Total inventory	$	41,905	$	24,968

As of December 31, 2020, total inventory included $37.8 million related to CINVANTI and $4.1 million related to SUSTOL. As of December 31, 2019, total inventory included $23.5 million related to CINVANTI and $1.5 million related to SUSTOL. In addition, cost of product sales for the years ended December 31, 2020 and 2019 included charges of $0.1 million and $3.3 million, respectively, resulting from the write-off of short-dated SUSTOL inventory.

Property and Equipment

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

	December 31,
	2020			2019
Scientific equipment	$	29,135		$	24,603
Leasehold improvements		878			206
Computer equipment and software		1,461			1,314
Furniture, fixtures and office equipment		2,135			1,520
Property and equipment, gross		33,609			27,643
Less: accumulated depreciation and amortization		(10,872	)		(8,025	)
Property and equipment, net	$	22,737		$	19,618

Depreciation and amortization expense for the years ended December 31, 2020, 2019 and 2018 was $2.8 million, $2.0 million and $1.5 million, respectively. As of December 31, 2020 and 2019, $14.1 million and $13.5 million of property and equipment, respectively, was in process and not depreciated during the respective years.

Accrued Payroll and Employee Liabilities and Other Accrued Liabilities

Accrued payroll and employee liabilities consist of the following (in thousands):

	December 31,
	2020		2019
Accrued employee salaries and benefits	$	1,691	$	3,047
Accrued bonuses		8,479		9,545
Accrued vacation		3,427		2,656
Total accrued payroll and employee liabilities	$	13,597	$	15,248

Other accrued liabilities consist of the following (in thousands):

	December 31,
	2020		2019
Accrued product sales allowances	$	24,571	$	27,939
Accrued consulting and professional fees		3,450		7,742
Accrued accounts payable		104		310
Other accrued liabilities		244		544
Total other accrued liabilities	$	28,369	$	36,535

Revenue Recognition

12 Months Ended

Dec. 31, 2020

Revenue From Contract With Customer [Abstract]

Revenue Recognition

5.	Revenue Recognition

Product Sales

CINVANTI and SUSTOL are distributed in the U.S. through a limited number of Customers that resell to healthcare providers and hospitals, the end users of CINVANTI and SUSTOL.

Adoption of Topic 606

On January 1, 2018, we adopted Topic 606 using the modified retrospective approach applied to those contracts that were not completed as of January 1, 2018. With the adoption of Topic 606, we recognize product sales as revenue when our products are sold to our Customers (sell-in approach). Product sales under Topic 606 are reported net of product sales allowances, which include product returns.

Revenue is recognized in an amount that reflects the consideration we expect to receive in exchange for our products. To determine revenue recognition for contracts with customers within the scope of Topic 606, we performed the following 5 steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations of the contract(s); (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract(s); and (v) recognize revenue when (or as) we satisfy the performance obligations.

Product Sales Allowances

We recognize product sales allowances as a reduction of product sales in the same period the related revenue is recognized. Product sales allowances are based on amounts owed or to be claimed on the related sales. These estimates take into consideration the terms of our agreements with Customers, historical product returns, rebates or discounts taken, the shelf life of the product and specific known market events, such as competitive pricing and new product introductions. If actual future results vary from our estimates, we may need to adjust these estimates, which could have an effect on product sales and earnings in the period of adjustment. Our product sales allowances include:

•

Product Returns—We allow our Customers to return product for credit for up to 12 months after its product expiration date. As such, there may be a significant period of time between the time the product is shipped and the time the credit is issued on returned product.

•

Distributor Fees—We offer contractually determined discounts to our Customers. These discounts are paid no later than two months after the quarter in which product was shipped.

•

Group Purchasing Organization (“GPO”) Discounts and Rebates—We offer cash discounts to GPO members. These discounts are taken when the GPO members purchase product from our Customers, who then charge back to us the discount amount. Additionally, we offer volume and contract-tier rebates to GPO members. Rebates are based on actual purchase levels during the quarterly rebate purchase period.

•

GPO Administrative Fees—We pay administrative fees to GPOs for services and access to data. These fees are based on contracted terms and are paid after the quarter in which the product was purchased by the GPOs’ members.

•

Medicaid Rebates—We participate in Medicaid rebate programs, which provide assistance to certain low-income patients based on each individual state’s guidelines regarding eligibility and services. Under the Medicaid rebate programs, we pay a rebate to each participating state, generally within three months after the quarter in which product was sold.

We believe our estimated allowance for product returns requires a high degree of judgment and is subject to change based on our experience and certain quantitative and qualitative factors. We believe our estimated allowances for distributor fees, GPO discounts, rebates and administrative fees and Medicaid rebates do not require a high degree of judgment because the amounts are settled within a relatively short period of time.

Our product sales allowances and related accruals are evaluated each reporting period and adjusted when trends or significant events indicate that a change in estimate is appropriate. Changes in product sales allowance estimates could materially affect our results of operations and financial position.

Net product sales for the year ended December 31, 2020 were $88.6 million, compared to $146.0 million for the same period in 2019. For the year ended December 31, 2020, net products sales of CINVANTI were $87.8 million, compared to $132.2 million for the same period in 2019. For the year ended December 31, 2020, net product sales of SUSTOL were $0.8 million, compared to $13.8 million for the same period in 2019.

The following table provides a summary of activity with respect to our product returns, distributor fees and discounts, rebates and administrative fees, which are included in other accrued liabilities on the consolidated balance sheets (in thousands):

							Discounts,
							Rebates and
	Product			Distributor			Administrative
	Returns			Fees			Fees			Total
Balance at December 31, 2019	$	2,351		$	3,999		$	21,589		$	27,939
Provision		498			15,964			102,603			119,065
Payments/credits		(145	)		(16,033	)		(106,255	)		(122,433	)
Balance at December 31, 2020	$	2,704		$	3,930		$	17,937		$	24,571

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-URI http://asc.fasb.org/topic&trid=49130388

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130551-203045

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130556-203045

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130550-203045

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130558-203045

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

+ Details

Commitments and Contingencies

12 Months Ended

Dec. 31, 2020

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

6.	Commitments and Contingencies

Leases

As of December 31, 2020, we had an operating lease for 73,328 square feet of laboratory and office space in San Diego, California, with a lease term that expires on December 31, 2025. We have one 5-year option to renew this lease on expiration. During the year ended December 31, 2020, we paid $3.6 million for our operating lease.

We leased 26,067 square feet of laboratory, office and warehouse space in Redwood City, California. The lease for the Redwood City space expired in May 2019. In March 2018, we entered into a sublease agreement for the Redwood City property. The sublease agreement expired in May 2019. We also leased 1,898 square feet of office space in Jersey City, New Jersey. The lease for the Jersey City office space expired in December 2019.

Annual future minimum lease payments as of December 31, 2020 are as follows (in thousands):

Year ended December 31:
2021	$	3,942
2022		4,058
2023		4,178
2024		4,274
2025		4,379
Thereafter		—
Total future minimum lease payments		20,831
Less: discount		(3,273	)
Total lease liabilities	$	17,558

Rent expense under all operating leases totaled $3.9 million, $3.1 million and $3.2 million for the years ended December 31, 2020, 2019 and 2018, respectively.

Development Agreements

We enter into agreements with clinical sites and clinical research organizations for the conduct of our clinical trials and contract manufacturing organizations for the manufacture and supply of preclinical, clinical and commercial materials and drug product. We make payments to these clinical sites and clinical research organizations based in part on the number of eligible patients enrolled and the length of their participation in the clinical trials. In some of our agreements with contract manufacturing organizations, we are required to meet minimum purchase obligations. Under certain of these agreements, we may be subject to penalties in the event that we prematurely terminate these agreements. At this time, due to the variability associated with clinical site agreements, contract research organization agreements and contract manufacturing agreements, we are unable to estimate with certainty the future costs we will incur. We intend to use our current financial resources to fund our obligations under these commitments.

Reorganization

12 Months Ended

Dec. 31, 2020

Reorganizations [Abstract]

Reorganization

7.	Reorganization

In October 2020, we implemented changes to our organizational structure. In connection with the reorganization, we provided or will provide employees one-time severance payments upon termination, continued benefits for a specified period of time, outplacement services and certain stock option modifications.

The total expense for these activities was $5.6 million, $2.5 million of which is primarily for severance and $3.1 million of which is for non-cash, stock-based compensation expense. For the year ended December 31, 2020, total expenses were $5.6 million, with $1.2 million in research and development expense, $3.7 million in general and administrative expense and $0.7 million in sales and marketing expense. As of December 31, 2020, we had paid $2.4 million of the total cash severance charges. We have accounted for these expenses in accordance with the FASB ASC Topic 420, Exit or Disposal Cost Obligations.

Secured Notes to Related Party

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Secured Notes to Related Party

8.	Secured Notes to Related Party

Convertible Notes

In April 2011, we entered into a securities purchase agreement for a private placement of up to $4.5 million in Convertible Notes with certain investors, including Tang Capital Partners, LP (“TCP”). TCP is controlled by Tang Capital Management, LLC (“TCM”). The manager of TCM is Kevin Tang, who served as a director at the time. At the time of issuance, the terms of the Convertible Notes were determined by our independent directors to be no less favorable than terms that would be obtained in an arm’s length financing transaction. We received a total of $4.3 million, net of issuance costs, from the issuance of these Convertible Notes.

The Convertible Notes are secured by substantially all of our assets, including placing our bank and investment accounts under a control agreement. The Convertible Notes bear interest at 6% per annum, payable quarterly in cash or in additional principal amount of Convertible Notes, at the election of the purchasers. The Convertible Notes mature on May 2, 2021; however, the holders of the Convertible Notes may require prepayment of the Convertible Notes at any time, at each holder’s option.

The Convertible Notes are convertible into shares of our common stock at a rate of 1,250 shares for every $1,000 of outstanding principal due under the Convertible Notes. There is no right to convert the Convertible Notes to the extent that, after giving effect to such conversion, the holder would beneficially own in excess of 9.99% of our outstanding common stock. Each holder of the Convertible Notes can increase or decrease this beneficial ownership conversion limit by written notice to us, which will not be effective until 61 days after delivery of the notice.

As of December 31, 2020, we were in compliance with all covenants under the Convertible Notes. On the occurrence of an event of default under the Convertible Notes, the holders of the Convertible Notes have the right to require us to redeem all or a portion of their Convertible Notes.

In 2011, we filed a registration statement with the SEC to register for resale 3.5 million shares underlying the Convertible Notes. The registration statement was declared effective on July 29, 2011. The Convertible Note holders have agreed to waive their right to require us to maintain the effectiveness of the registration statement and to register the additional shares underlying the Convertible Notes until they provide notice otherwise.

The Convertible Notes contain an embedded conversion feature that was in-the-money on the issuance dates. Based on an effective fixed conversion rate of 1,250 shares for every $1,000 of principal and accrued interest due under the Convertible Notes, the total conversion benefit at issuance exceeded the loan proceeds. Therefore, a debt discount was recorded in an amount equal to the face value of the Convertible Notes on the issuance dates, and we began amortizing the resultant debt discount over the respective 10-year term of the Convertible Notes. During the year ended December 31, 2020, accrued interest of $0.4 million was paid-in-kind and rolled into the Convertible Note principal balance, which resulted in an additional debt discount of $0.4 million. For the years ended December 31, 2020, 2019 and 2018, interest expense relating to the stated rate was $0.4 million for each of the three periods. Interest expense relating to the amortization of the debt discount was $1.4 million, $1.1 million and $0.9 million, respectively.

As of December 31, 2020, the carrying value of the Convertible Notes was $7.1 million, which is comprised of the $7.6 million principal amount of the Convertible Notes outstanding, less a debt discount of $0.5 million. As of December 31, 2020, the Convertible Notes were convertible into 9.5 million shares of our common stock.

Promissory Note

In August 2016, we entered into the Subordinated Secured Promissory Note (“Promissory Note”) with TCP whereby TCP agreed to lend us up to $100.0 million. The Promissory Note had a two-year term and bore interest at a rate of 8% per annum. The first close of $50.0 million occurred on August 5, 2016. The second close of an additional $50.0 million was not drawn and expired prior to the draw down. There were no fees, no warrants and no equity conversion features associated with this transaction. The Promissory Note was secured by a second-priority lien on substantially all of our assets. TCP is controlled by TCM. The manager of TCM is Kevin Tang, who served as the Chairman of our Board of Directors at the time. The terms of the Promissory Note were determined by our independent directors to be no less favorable than terms that would be obtained in an arm’s length financing transaction.

For the year ended December 31, 2018, interest expense was $1.2 million. In August 2018, we paid the remaining obligation under the Promissory Note, which included $25.0 million of outstanding principal and $0.2 million of accrued interest. As of December 31, 2018, there were no remaining obligations under the Promissory Note.

Stockholders' Equity

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Stockholders’ Equity

9.	Stockholders’ Equity

2018 Common Stock Offerings

In April 2018, we sold 6.9 million shares of our common stock at a public offering price of $26.00 per share. We received total net cash proceeds of $168.7 million (net of $10.7 million in issuance costs) from the sale of the common stock.

In June 2018, we sold 5.1 million shares of our common stock at a public offering price of $39.50 per share. We received total net cash proceeds of $194.4 million (net of $5.6 million in issuance costs) from the sale of the common stock.

2019 Common Stock Offerings

In October 2019, we sold 9.9 million shares of our common stock at a public offering price of $17.50 per share. We received total net cash proceeds of $162.2 million (net of $10.3 million in issuance costs) from the sale of the common stock.

Public Offering Warrants

In June 2014, as a component of our public offering, we sold 600,000 pre-funded warrants to purchase shares of our common stock. The pre-funded warrants have an exercise price of $0.01 per share and expire on June 30, 2021. During the year ended December 31, 2017, warrant holders exercised 4,426 warrants under the cashless exercise provision in each such holder’s warrant, which resulted in the net issuance of 4,423 shares of common stock and no net cash proceeds to us. During the year ended December 31, 2019, warrant holders exercised 132,130 warrants, which resulted in the issuance of 132,130 shares for net cash proceeds of $1,321. During the year ended December 31, 2020, warrant holders exercised 267,870 warrants, which resulted in the issuance of 267,870 shares for net cash proceeds of $2,679. As of December 31, 2020, 195,574 warrants from the June 2014 public offering remain outstanding.

Common Stock Reserved for Future Issuance

Shares of our common stock reserved for future issuance as of December 31, 2020 were as follows:

	Number of
	Shares
Stock options outstanding		18,912,529
Restricted stock units outstanding		602,741
Stock options available for grant		1,575,955
Employee Stock Purchase Plan		176,250
Warrants outstanding		220,164
Shares of common stock underlying Convertible Notes outstanding (see Note 8)		9,510,208
Total shares reserved for future issuance		30,997,847

Employee Stock Purchase Plan

In 1997, our stockholders approved our Employee Stock Purchase Plan (“ESPP”) at which time a maximum of 10,000 shares of common stock were available for issuance. In December 2007, May 2009, June 2011, May 2014, May 2015, June 2016, June 2017 and June 2019, our stockholders authorized increases in the number of shares reserved for issuance under the ESPP by 5,000, 10,000, 25,000, 25,000, 100,000, 100,000, 200,000 and 300,000 shares, respectively, for a total of 775,000 shares reserved at December 31, 2020. Under the terms of the ESPP, employees can elect to have up to a maximum of 10% of their base earnings withheld to purchase shares of our common stock. The purchase price of the stock is 85% of the lower of the closing prices for our common stock on either: (i) the first trading day in the enrollment period, as defined in the ESPP, in which the purchase is made, or (ii) the purchase date. The length of the enrollment period is 6 months. Enrollment dates are the first business day of May and November. Under the ESPP, we issued 193,841, 125,727, and 71,499 shares in 2020, 2019 and 2018, respectively. The weighted-average exercise price per share of the purchase rights exercised during 2020, 2019 and 2018 was $11.95, $16.77 and $16.48, respectively. As of December 31, 2020, 598,750 shares of common stock have been issued under the ESPP and 176,250 shares of common stock are available for future issuance.

Stock Option Plans

We currently have one stock option plan from which we can grant options and restricted stock awards to employees, officers, directors and consultants. In December 2007, the stockholders approved our 2007 Amended and Restated Equity Incentive Plan (“2007 Plan”) at which time a maximum of 150,000 shares of common stock were available for grant. In May 2010, June 2011, May 2014, May 2015, June 2016, June 2017 and June 2019, our stockholders approved amendments to our 2007 Plan to increase the maximum number of shares of common stock available for grant by 100,000, 4,500,000, 1,750,000, 4,300,000, 3,000,000, 5,000,000 and 7,000,000 shares of common stock, respectively, resulting in an aggregate of 25,800,000 shares of common stock authorized for issuance as of December 31, 2020. At December 31, 2020, there were 1,575,955 shares available for future grant under the 2007 Plan. Any shares that are issuable on exercise of options granted that expire, are cancelled or that we receive pursuant to a net exercise of options are available for future grant and issuance.

In 2014, 2013 and 2012, we granted options to certain employees outside of our stockholder approved stock option plans. All options to purchase our common stock were granted with an exercise price that equals fair market value of the underlying common stock on the grant dates and expire no later than 10 years from the date of grant. The options are exercisable in accordance with vesting schedules that generally provide for them to be fully vested and exercisable 4 years after the date of grant, provided, however, that we have also issued stock options awards that are subject to performance vesting requirements. All stock option grants issued outside of our stockholder approved plans have been registered on Form S-8 with the SEC.

In 2020, we began granting restricted stock units (“RSUs”) to employees and non-employee directors pursuant to the 2007 Plan. We satisfy such grants through the issuance of new shares upon vesting.

The following table summarizes the stock option plan activity (including RSUs):

	Outstanding Options
				Weighted-
				Average
	Number of			Exercise
	Shares			Price
Balance at December 31, 2017		13,462,964		$	15.03
Granted		4,052,011		$	26.83
Exercised		(1,529,509	)	$	11.97
Cancelled		(720,859	)	$	17.98
Balance at December 31, 2018		15,264,607		$	18.33
Granted		4,933,480		$	24.21
Exercised		(1,983,221	)	$	11.18
Cancelled		(1,550,226	)	$	23.26
Balance at December 31, 2019		16,664,640		$	20.47
Granted		4,659,942		$	13.95
Exercised		(544,441	)	$	12.41
Cancelled		(1,264,871	)	$	22.84
Balance at December 31, 2020		19,515,270		$	18.98

For the year ended December 31, 2020, equity awards cancelled (included in the above table) consisted of 922,578 options and RSUs forfeited with a weighted-average exercise price of $22.76 and 342,293 options expired with a weighted-average exercise price of $23.04.

As of December 31, 2020, options exercisable have a weighted-average remaining contractual term of 5.7 years. The total intrinsic value of stock option exercises, which is the difference between the exercise price and closing price of our common stock on the date of exercise, during the years ended December 31, 2020 and 2019 was $3.2 million and $25.0 million, respectively. As of December 31, 2020 and 2019, the total intrinsic value of options outstanding and exercisable was $69.1 million and $56.3 million, respectively.

	Years Ended December 31,
	2020				2019				2018
			Weighted-				Weighted-				Weighted-
			Average				Average				Average
			Exercise				Exercise				Exercise
	Options		Price		Options		Price		Options		Price
Exercisable at end of year		10,237,202	$	18.74		7,436,379	$	17.02		6,523,093	$	14.83
Options vested or expected to vest		18,179,553	$	19.58		15,962,432	$	20.31		14,449,017	$	18.11

Exercise prices and weighted-average remaining contractual lives for the options outstanding as of December 31, 2020 were:

									Weighted-
			Weighted-						Average
			Average		Weighted-				Exercise
			Remaining		Average				Price of
Options		Range of	Contractual		Exercise		Options		Options
Outstanding		Exercise Prices	Life (in years)		Price		Exercisable		Exercisable
	2,700,473	$5.20–$13.00		3.97	$	10.14		2,691,327	$	10.14
	800,371	$13.05–$15.55		6.13		14.31		655,173		14.22
	3,582,407	$15.72		9.75		15.72		149,197		15.72
	2,838,033	$15.78–$17.89		6.10		16.87		2,348,090		16.84
	3,688,255	$18.00–$24.97		7.15		22.97		2,036,430		23.10
	3,498,912	$25.02		8.63		25.02		1,010,859		25.02
	1,804,078	$25.06–$39.00		6.64		30.58		1,346,126		30.43
	18,912,529			7.21		19.59		10,237,202		18.74

On December 31, 2020, we had reserved 19,515,270 shares of common stock for future issuance on exercise of outstanding options and vesting of outstanding restricted stock units granted under the 2007 Plan, as well as the non-plan grants.

Valuation and Expense Information

The following table summarizes stock-based compensation expense related to stock-based payment awards pursuant to our equity compensation arrangements (in thousands):

	December 31,
	2020		2019		2018
Research and development	$	20,731	$	19,202	$	13,689
General and administrative		15,601		13,564		9,630
Sales and marketing		13,886		18,645		10,048
Total stock-based compensation expense	$	50,218	$	51,411	$	33,367

As of December 31, 2020, there was $116.1 million of total unrecognized compensation cost related to non-vested, stock-based payment awards granted under all of our equity compensation plans and all non-plan option grants. Total unrecognized compensation cost will be adjusted for future changes in estimated forfeitures. We expect to recognize this compensation cost over a weighted-average period of 2.8 years.

The fair value of RSUs is estimated based on the closing market price of our common stock on the date of the grant. RSUs generally vest quarterly over a four-year period.

We estimated the fair value of each option grant and ESPP purchase right on the date of grant using the Black-Scholes option pricing model with the following weighted-average assumptions:

Options:

	December 31,
	2020			2019			2018
Risk-free interest rate		0.5	%		1.8	%		2.8	%
Dividend yield		—	%		—	%		—	%
Volatility		69.4	%		66.5	%		70.4	%
Expected life (years)		6			6			6

ESPP:

	December 31,
	2020			2019			2018
Risk-free interest rate		0.1	%		1.9	%		2.4	%
Dividend yield		—	%		—	%		—	%
Volatility		67.7	%		52.1	%		59.7	%
Expected life (months)		6			6			6

The weighted-average fair value of options granted was $9.76, $14.70 and $17.24 for the years ended December 31, 2020, 2019 and 2018, respectively.

The weighted-average fair value of shares purchased through the ESPP was $5.18, $5.94 and $9.95 for the years ended December 31, 2020, 2019 and 2018, respectively.

The risk-free interest rate assumption is based on observed interest rates on U.S. Treasury debt securities with maturities close to the expected term of our employee and director stock options and ESPP purchases.

The dividend yield assumption is based on our history and expectation of dividend payouts. We have never paid dividends on our common stock, and we do not anticipate paying dividends in the foreseeable future.

We used our historical stock price to estimate volatility.

The expected life of employee and director stock options represents the average of the contractual term of the options and the weighted-average vesting period, as permitted under the simplified method. We have elected to use the simplified method, as we do not have enough historical exercise experience to provide a reasonable basis on which to estimate the expected term. The expected life for the ESPP purchase rights is 6 months, which represents the length of each purchase period.

Income Taxes

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Income Taxes

10.	Income Taxes

For the years ended December 31, 2020, 2019 and 2018, we did not record a provision for income taxes due to a full valuation allowance against our deferred tax assets.

The difference between the provision for income taxes and income taxes computed using the effective U.S. federal statutory rate is as follows (in thousands):

	December 31,
	2020			2019			2018
Tax at statutory federal rate	$	(47,728	)	$	(42,997	)	$	(37,557	)
State tax, net of federal benefit		(8,218	)		(9,823	)		(6,527	)
Research and development credits		(4,327	)		(4,855	)		(4,775	)
Stock-based compensation expense		4,675			2,906			(2,059	)
Non-deductible compensation		1,455			4,720			901
Change in valuation allowance		53,621			49,479			50,834
Other		522			570			(817	)
Provision for income taxes	$	—		$	—		$	—

Deferred income tax assets and liabilities arising from differences between accounting for financial statement purposes and tax purposes, less valuation allowance at year-end are as follows (in thousands):

	December 31,
	2020			2019
Deferred tax assets:
Net operating loss carryforward	$	251,971		$	210,301
Research and development credits		49,683			42,490
Stock-based compensation		20,211			15,628
Lease liabilities		4,330			3,487
Other		3,777			3,818
Total gross deferred tax assets		329,972			275,724
Deferred tax liabilities:
Right-of-use lease assets		(4,014	)		(3,385	)
Total gross deferred tax liabilities		(4,014	)		(3,385	)
Valuation allowance		(325,958	)		(272,339	)
Net deferred tax assets	$	—		$	—

We have established a valuation allowance to offset net deferred tax assets as of December 31, 2020 and 2019 due to the uncertainty of realizing future tax benefits from such assets.

As of December 31, 2020, we had federal, California and other state net operating loss (“NOL”) carryforwards of $1.0 billion, $111.9 million and $515.5 million, respectively. The federal NOL carryforwards consist of $549.7 million generated before January 1, 2018, which will begin to expire in 2021, and $492.0 million that can be carried forward indefinitely, but are subject to the 80% taxable income limitation. The state NOL carryforwards will begin to expire in 2028.

As of December 31, 2020, we had federal and state research and development credit carryforwards of $39.4 million and $18.1 million, respectively. The federal research and development credit carryforwards will begin to expire in 2022. The state research and development credit carryforwards will begin to expire in 2023.

Internal Revenue Code (“IRC”) Sections 382 and 383 place a limitation on the amount of taxable income that can be offset by NOL and credit carryforwards after a change in control (generally greater than 50% change in ownership within a three-year period) of a loss corporation. Generally, after a change in control, a loss corporation cannot deduct NOL and credit carryforwards in excess of the IRC Sections 382 and 383 limitation. State jurisdictions have similar rules. We have previously performed an analysis of IRC Sections 382 and 383 through 2018 and determined there were ownership changes in 2007, 2011 and 2013. We are currently in the process of updating our IRC Sections 382 and 383 analysis through 2020. The limitation in the federal and state NOL and research and development credit carryforwards that expire unused would reduce the deferred tax assets, which are fully offset by a valuation allowance.

We file U.S. and state income tax returns with varying statutes of limitations. The tax years from 2002 to 2020 remain open to examination due to the carryover of unused NOL carryforwards and tax credits.

A reconciliation of our unrecognized tax benefits is as follows (in thousands):

	Year Ended December 31,
	2020		2019		2018
Balance at beginning of year	$	4,784	$	2,385	$	120
Additions for tax positions of prior years		341		147		—
Additions based on tax positions related to current year		2,281		2,252		2,265
Balance at end of year	$	7,406	$	4,784	$	2,385

Due to our valuation allowance, the $7.4 million of unrecognized tax benefits would not affect the effective tax rate, if recognized. It is the Company’s practice to recognize interest and penalties related to income tax matters in income tax expense. As of December 31, 2020, we had no accrued interest and penalties related to uncertain tax positions. We do not expect any material changes to the estimated amount of liability associated with our uncertain tax positions within the next 12 months.

On March 27, 2020, the Coronavirus Aid, Relief and Economic Security Act (“CARES Act”) was enacted and signed into law in response to the COVID-19 pandemic. GAAP requires recognition of the tax effects of new legislation during the reporting period that includes the enactment date. The CARES Act includes changes to the tax provisions that benefits business entities and makes certain technical corrections to the 2017 Tax Cuts and Jobs Act. The tax relief measures for businesses include a five-year net operating loss carryback, suspension of the annual deduction limitation of 80% of taxable income from net operating losses generated in a tax year beginning after December 31, 2017, changes in the deductibility of interest, acceleration of alternative minimum tax credit refunds, payroll tax relief, technical corrections on net operating loss carryforwards for fiscal year taxpayers and allows accelerated deduction qualified improvement property. The CARES Act also provides other non-tax benefits to assist those impacted by the pandemic. We evaluated the impact of the CARES Act and determined that there was no material impact for the year ended December 31, 2020.

On June 29, 2020, California Assembly Bill 85 was signed into law. The legislation suspends the California net operating loss deductions for 2020, 2021, and 2022 for certain taxpayers and imposes a limitation of certain California tax credits for 2020, 2021, and 2022. The legislation disallows the use of California net operating loss deductions if the taxpayer recognizes business income and its adjusted gross income is greater than $1,000,000. The carryover periods for net operating loss deductions disallowed by this provision will be extended. Additionally, any business credit will only offset a maximum of $5,000,000 of California tax. Given our loss position in the current year, the new legislation did not impact the current year provision or our financial statements for the year ended December 31, 2020. We will continue to monitor possible California net operating loss and credit limitations in future periods.

On December 27, 2020, the “Consolidated Appropriations Act, 2021” was enacted and signed into law to further COVID-19 economic relief and extend certain expiring tax provisions. The relief package includes a tax provision clarifying that businesses with forgiven PPP loans can deduct regular business expenses that are paid for with the loan proceeds. Additional pandemic relief tax measures include an expansion of the employee retention credit, enhanced charitable contribution deductions, and a temporary full deduction for business expenses for food

and beverages provided by a restaurant. The provisions did not have a material impact on our financial statements for the year ended December 31, 2020.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

Other Income (Expense), Net

12 Months Ended

Dec. 31, 2020

Other Income And Expenses [Abstract]

Other Income (Expense), Net

11.	Other Income (Expense), Net

In 2018, we recorded $1.9 million in income to other income (expense), net resulting from the disgorgement of short-swing profits arising from the sales of our common stock by a beneficial owner pursuant to Section 16(b) of the Securities and Exchange Act of 1934.

Employee Benefit Plan

12 Months Ended

Dec. 31, 2020

Compensation And Retirement Disclosure [Abstract]

Employee Benefit Plan

12.	Employee Benefit Plan

We have a defined contribution 401(k) plan (“Plan”) covering substantially all of our employees. In the past three calendar years, we made matching cash contributions equal to 50% of each participant’s contribution during the Plan year up to a maximum amount equal to the lesser of 3% of each participant’s annual compensation or $8,550, $8,400 and $8,250 for the years ended December 31, 2020, 2019 and 2018, respectively. Such amounts were recorded as expense in the corresponding years. We may also contribute additional discretionary amounts to the Plan as we determine. For the years ended December 31, 2020, 2019 and 2018, we contributed $1.1 million, $1.0 million and $0.7 million, respectively, to the Plan. No discretionary contributions have been made to the Plan since its inception.

- Definition

The entire disclosure for retirement benefits.

+ References

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+ Details

Summary of Quarterly Consolidated Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2020

Quarterly Financial Information Disclosure [Abstract]

Summary of Quarterly Consolidated Financial Data (Unaudited)

13.	Summary of Quarterly Consolidated Financial Data (Unaudited)

The following is a summary of the unaudited quarterly results of operations for the years ended December 31, 2020 and 2019:

	2020
	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
	(In thousands, except per share amounts)
Revenues:
Net product sales	$	25,400		$	22,668		$	19,965		$	20,605
Cost of product sales		(10,622	)		(9,005	)		(7,170	)		(9,392	)
Gross Profit		14,778			13,663			12,795			11,213
Operating expenses:
Research and development		36,894			44,004			49,182			44,453
General and administrative		10,422			9,819			9,482			12,503
Sales and marketing		20,196			15,589			12,515			15,553
Loss from operations		(52,734	)		(55,749	)		(58,384	)		(61,296	)
Other income (expense), net		1,155			559			156			(985	)
Net loss	$	(51,579	)	$	(55,190	)	$	(58,228	)	$	(62,281	)
Basic and diluted net loss per share	$	(0.57	)	$	(0.61	)	$	(0.64	)	$	(0.68	)

	2019
	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
	(In thousands, except per share amounts)
Revenues:
Net product sales	$	31,602		$	36,659		$	42,624		$	35,083
Cost of product sales		(14,962	)		(13,588	)		(17,195	)		(15,874	)
Gross Profit		16,640			23,071			25,429			19,209
Operating expenses:
Research and development		42,972			41,425			34,708			48,277
General and administrative		9,648			9,778			8,597			9,874
Sales and marketing		28,720			23,647			16,977			20,420
Loss from operations		(64,700	)		(51,779	)		(34,853	)		(59,362	)
Other income, net		1,688			1,557			1,258			1,442
Net loss	$	(63,012	)	$	(50,222	)	$	(33,595	)	$	(57,920	)
Basic and diluted net loss per share	$	(0.80	)	$	(0.63	)	$	(0.42	)	$	(0.65	)

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Principles of Consolidation

Therapeutics B.V. has no operations and no material assets or liabilities, and there have been no significant transactions related to Heron Therapeutics B.V. since its inception.

Use of Estimates

Cash, Cash Equivalents and Short-term Investments

Cash and cash equivalents consist of cash and highly liquid investments with contractual maturities of three months or less from the original purchase date.

Our bank and investment accounts have been placed under control agreements in accordance with our Senior Secured Convertible Notes (“Convertible Notes”) (see Note 8).

Fair Value of Financial Instruments

Concentration of Credit Risk

The following table includes the percentage of net product sales and accounts receivable balances for our three major Customers, each of which comprised 10% or more of our net product sales:

	Net Product Sales			Accounts Receivable
	Year Ended December 31, 2020			As of December 31, 2020
Customer A		44.0	%		61.3	%
Customer B		33.5	%		29.8	%
Customer C		20.8	%		8.5	%
Total		98.3	%		99.6	%

Accounts Receivable, Net

Inventory

Property and Equipment

improvements are stated at cost and amortized on a straight-line basis over the shorter of the estimated useful life of the asset or the lease term.

Impairment of Long-Lived Assets

Leases

Revenue Recognition

Accrued Clinical Liabilities

Research and Development Expense

Patent Costs

Stock-Based Compensation Expense

	December 31,
	2020		2019		2018
Stock options outstanding		18,912		16,665		15,265
Restricted stock units outstanding		603		—		—
Warrants outstanding		220		508		640
Shares of common stock underlying Convertible Notes outstanding		9,510		8,960		8,473

Recent Accounting Pronouncements

Adopted in 2020

Not Yet Adopted

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Percentage of Net Product Sales and Accounts Receivable Balance

The following table includes the percentage of net product sales and accounts receivable balances for our three major Customers, each of which comprised 10% or more of our net product sales:

	Net Product Sales			Accounts Receivable
	Year Ended December 31, 2020			As of December 31, 2020
Customer A		44.0	%		61.3	%
Customer B		33.5	%		29.8	%
Customer C		20.8	%		8.5	%
Total		98.3	%		99.6	%

Common Stock Equivalents Excluded From Computation of Net Loss Per Share

	December 31,
	2020		2019		2018
Stock options outstanding		18,912		16,665		15,265
Restricted stock units outstanding		603		—		—
Warrants outstanding		220		508		640
Shares of common stock underlying Convertible Notes outstanding		9,510		8,960		8,473

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis

We measure cash, cash equivalents and short-term investments at fair value on a recurring basis. The fair values of these such assets were as follows (in thousands):

	Fair Value Measurements at Reporting Date Using
	Balance at December 31, 2020		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash and money market funds	$	49,149	$	49,149	$	—	$	—
U.S. treasury bills and government agency obligations		20,276		—		20,276		—
U.S. corporate debt securities		11,547		—		11,547		—
Foreign corporate debt securities		15,557		—		15,557		—
U.S. commercial paper		27,996		—		27,996		—
Foreign commercial paper		83,966		—		83,966		—
Total	$	208,491	$	49,149	$	159,342	$	—

	Fair Value Measurements at Reporting Date Using
	Balance at December 31, 2019		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash and money market funds	$	56,931	$	56,931	$	—	$	—
U.S. treasury bills and government agency obligations		140,626		140,626		—		—
U.S. corporate debt securities		80,170		—		80,170		—
Foreign corporate debt securities		23,203		—		23,203		—
U.S. commercial paper		32,801		—		32,801		—
Foreign commercial paper		57,241		—		57,241		—
Total	$	390,972	$	197,557	$	193,415	$	—

Balance Sheet Details (Tables)

12 Months Ended

Dec. 31, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Summary of Short-Term Investments

The following is a summary of our short-term investments (in thousands):

	December 31, 2020
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
U.S. treasury bills and government agency obligations	$	20,110	$	166	$	—	$	20,276
U.S. corporate debt		11,505		42		—		11,547
Foreign corporate debt		15,508		49		—		15,557
U.S. commercial paper		13,997		—		—		13,997
Foreign commercial paper		41,976		—		—		41,976
Total	$	103,096	$	257	$	—	$	103,353

	December 31, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
U.S. treasury bills and government agency obligations	$	140,567	$	59	$	—	$	140,626
U.S. corporate debt securities		80,159		11		—		80,170
Foreign corporate debt securities		23,188		15		—		23,203
U.S. commercial paper		32,801		—		—		32,801
Foreign commercial paper		42,274		—		—		42,274
Total	$	318,989	$	85	$	—	$	319,074

Schedule of Inventory

Inventory consists of the following (in thousands):

	December 31,
	2020		2019
Raw materials	$	18,994	$	6,635
Work in process		6,847		12,571
Finished goods		16,064		5,762
Total inventory	$	41,905	$	24,968

Schedule of Property and Equipment, Net

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

	December 31,
	2020			2019
Scientific equipment	$	29,135		$	24,603
Leasehold improvements		878			206
Computer equipment and software		1,461			1,314
Furniture, fixtures and office equipment		2,135			1,520
Property and equipment, gross		33,609			27,643
Less: accumulated depreciation and amortization		(10,872	)		(8,025	)
Property and equipment, net	$	22,737		$	19,618

Schedule of Accrued Liabilities

Accrued payroll and employee liabilities consist of the following (in thousands):

	December 31,
	2020		2019
Accrued employee salaries and benefits	$	1,691	$	3,047
Accrued bonuses		8,479		9,545
Accrued vacation		3,427		2,656
Total accrued payroll and employee liabilities	$	13,597	$	15,248

Other accrued liabilities consist of the following (in thousands):

	December 31,
	2020		2019
Accrued product sales allowances	$	24,571	$	27,939
Accrued consulting and professional fees		3,450		7,742
Accrued accounts payable		104		310
Other accrued liabilities		244		544
Total other accrued liabilities	$	28,369	$	36,535

Revenue Recognition (Tables)

12 Months Ended

Dec. 31, 2020

Revenue From Contract With Customer [Abstract]

Summary of Activity to Product Returns, Distributor Fees and Discounts, Rebates and Administrative Fees

							Discounts,
							Rebates and
	Product			Distributor			Administrative
	Returns			Fees			Fees			Total
Balance at December 31, 2019	$	2,351		$	3,999		$	21,589		$	27,939
Provision		498			15,964			102,603			119,065
Payments/credits		(145	)		(16,033	)		(106,255	)		(122,433	)
Balance at December 31, 2020	$	2,704		$	3,930		$	17,937		$	24,571

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2020

Commitments And Contingencies Disclosure [Abstract]

Summary of Future Minimum Lease Payments

Annual future minimum lease payments as of December 31, 2020 are as follows (in thousands):

Year ended December 31:
2021	$	3,942
2022		4,058
2023		4,178
2024		4,274
2025		4,379
Thereafter		—
Total future minimum lease payments		20,831
Less: discount		(3,273	)
Total lease liabilities	$	17,558

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Summary of Common Stock Reserved for Future Issuance

Shares of our common stock reserved for future issuance as of December 31, 2020 were as follows:

	Number of
	Shares
Stock options outstanding		18,912,529
Restricted stock units outstanding		602,741
Stock options available for grant		1,575,955
Employee Stock Purchase Plan		176,250
Warrants outstanding		220,164
Shares of common stock underlying Convertible Notes outstanding (see Note 8)		9,510,208
Total shares reserved for future issuance		30,997,847

Summary of Stock Option Plan Activity (Including Restricted Stock Units)

The following table summarizes the stock option plan activity (including RSUs):

	Outstanding Options
				Weighted-
				Average
	Number of			Exercise
	Shares			Price
Balance at December 31, 2017		13,462,964		$	15.03
Granted		4,052,011		$	26.83
Exercised		(1,529,509	)	$	11.97
Cancelled		(720,859	)	$	17.98
Balance at December 31, 2018		15,264,607		$	18.33
Granted		4,933,480		$	24.21
Exercised		(1,983,221	)	$	11.18
Cancelled		(1,550,226	)	$	23.26
Balance at December 31, 2019		16,664,640		$	20.47
Granted		4,659,942		$	13.95
Exercised		(544,441	)	$	12.41
Cancelled		(1,264,871	)	$	22.84
Balance at December 31, 2020		19,515,270		$	18.98

Schedule of Options Exercisable, Vested or Expected to Vest

	Years Ended December 31,
	2020				2019				2018
			Weighted-				Weighted-				Weighted-
			Average				Average				Average
			Exercise				Exercise				Exercise
	Options		Price		Options		Price		Options		Price
Exercisable at end of year		10,237,202	$	18.74		7,436,379	$	17.02		6,523,093	$	14.83
Options vested or expected to vest		18,179,553	$	19.58		15,962,432	$	20.31		14,449,017	$	18.11

Schedule of Exercise Prices And Weighted-average Remaining Contractual Lives For Options Outstanding

Exercise prices and weighted-average remaining contractual lives for the options outstanding as of December 31, 2020 were:

									Weighted-
			Weighted-						Average
			Average		Weighted-				Exercise
			Remaining		Average				Price of
Options		Range of	Contractual		Exercise		Options		Options
Outstanding		Exercise Prices	Life (in years)		Price		Exercisable		Exercisable
	2,700,473	$5.20–$13.00		3.97	$	10.14		2,691,327	$	10.14
	800,371	$13.05–$15.55		6.13		14.31		655,173		14.22
	3,582,407	$15.72		9.75		15.72		149,197		15.72
	2,838,033	$15.78–$17.89		6.10		16.87		2,348,090		16.84
	3,688,255	$18.00–$24.97		7.15		22.97		2,036,430		23.10
	3,498,912	$25.02		8.63		25.02		1,010,859		25.02
	1,804,078	$25.06–$39.00		6.64		30.58		1,346,126		30.43
	18,912,529			7.21		19.59		10,237,202		18.74

Summary of Stock-Based Compensation Expense related to Stock-Based Payment Awards

The following table summarizes stock-based compensation expense related to stock-based payment awards pursuant to our equity compensation arrangements (in thousands):

	December 31,
	2020		2019		2018
Research and development	$	20,731	$	19,202	$	13,689
General and administrative		15,601		13,564		9,630
Sales and marketing		13,886		18,645		10,048
Total stock-based compensation expense	$	50,218	$	51,411	$	33,367

Summary of Fair Value of Option Grant and ESPP Purchase Right on Grant Date Using Black-Scholes Option Pricing Model

We estimated the fair value of each option grant and ESPP purchase right on the date of grant using the Black-Scholes option pricing model with the following weighted-average assumptions:

Options:

	December 31,
	2020			2019			2018
Risk-free interest rate		0.5	%		1.8	%		2.8	%
Dividend yield		—	%		—	%		—	%
Volatility		69.4	%		66.5	%		70.4	%
Expected life (years)		6			6			6

ESPP:

	December 31,
	2020			2019			2018
Risk-free interest rate		0.1	%		1.9	%		2.4	%
Dividend yield		—	%		—	%		—	%
Volatility		67.7	%		52.1	%		59.7	%
Expected life (months)		6			6			6

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expense (Benefit)

The difference between the provision for income taxes and income taxes computed using the effective U.S. federal statutory rate is as follows (in thousands):

	December 31,
	2020			2019			2018
Tax at statutory federal rate	$	(47,728	)	$	(42,997	)	$	(37,557	)
State tax, net of federal benefit		(8,218	)		(9,823	)		(6,527	)
Research and development credits		(4,327	)		(4,855	)		(4,775	)
Stock-based compensation expense		4,675			2,906			(2,059	)
Non-deductible compensation		1,455			4,720			901
Change in valuation allowance		53,621			49,479			50,834
Other		522			570			(817	)
Provision for income taxes	$	—		$	—		$	—

Schedule of Deferred Tax Assets and Liabilities

	December 31,
	2020			2019
Deferred tax assets:
Net operating loss carryforward	$	251,971		$	210,301
Research and development credits		49,683			42,490
Stock-based compensation		20,211			15,628
Lease liabilities		4,330			3,487
Other		3,777			3,818
Total gross deferred tax assets		329,972			275,724
Deferred tax liabilities:
Right-of-use lease assets		(4,014	)		(3,385	)
Total gross deferred tax liabilities		(4,014	)		(3,385	)
Valuation allowance		(325,958	)		(272,339	)
Net deferred tax assets	$	—		$	—

Summary of Unrecognized Tax Benefits

A reconciliation of our unrecognized tax benefits is as follows (in thousands):

	Year Ended December 31,
	2020		2019		2018
Balance at beginning of year	$	4,784	$	2,385	$	120
Additions for tax positions of prior years		341		147		—
Additions based on tax positions related to current year		2,281		2,252		2,265
Balance at end of year	$	7,406	$	4,784	$	2,385

Summary of Quarterly Consolidated Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2020

Quarterly Financial Information Disclosure [Abstract]

Summary of Unaudited Quarterly Results of Operations

The following is a summary of the unaudited quarterly results of operations for the years ended December 31, 2020 and 2019:

	2020
	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
	(In thousands, except per share amounts)
Revenues:
Net product sales	$	25,400		$	22,668		$	19,965		$	20,605
Cost of product sales		(10,622	)		(9,005	)		(7,170	)		(9,392	)
Gross Profit		14,778			13,663			12,795			11,213
Operating expenses:
Research and development		36,894			44,004			49,182			44,453
General and administrative		10,422			9,819			9,482			12,503
Sales and marketing		20,196			15,589			12,515			15,553
Loss from operations		(52,734	)		(55,749	)		(58,384	)		(61,296	)
Other income (expense), net		1,155			559			156			(985	)
Net loss	$	(51,579	)	$	(55,190	)	$	(58,228	)	$	(62,281	)
Basic and diluted net loss per share	$	(0.57	)	$	(0.61	)	$	(0.64	)	$	(0.68	)

	2019
	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
	(In thousands, except per share amounts)
Revenues:
Net product sales	$	31,602		$	36,659		$	42,624		$	35,083
Cost of product sales		(14,962	)		(13,588	)		(17,195	)		(15,874	)
Gross Profit		16,640			23,071			25,429			19,209
Operating expenses:
Research and development		42,972			41,425			34,708			48,277
General and administrative		9,648			9,778			8,597			9,874
Sales and marketing		28,720			23,647			16,977			20,420
Loss from operations		(64,700	)		(51,779	)		(34,853	)		(59,362	)
Other income, net		1,688			1,557			1,258			1,442
Net loss	$	(63,012	)	$	(50,222	)	$	(33,595	)	$	(57,920	)
Basic and diluted net loss per share	$	(0.80	)	$	(0.63	)	$	(0.42	)	$	(0.65	)

Organization and Business - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)
Business [Line Items]
Cash, cash equivalents and short-term investments	$ 208.5
HTX-034
Business [Line Items]
Percentage of patients remained opioid free	45.50%
Percentage of reduction in pain intensity	71.00%

Summary of Significant Accounting Policies - Percentage of Net Product Sales and Accounts Receivable Balance (Details) - Customer Concentration Risk	12 Months Ended
	Dec. 31, 2020
Revenue Benchmark
Product Information [Line Items]
Concentration risk percentage	98.30%
Revenue Benchmark \| Largest Customer
Product Information [Line Items]
Concentration risk percentage	44.00%
Revenue Benchmark \| Second Largest Customer
Product Information [Line Items]
Concentration risk percentage	33.50%
Revenue Benchmark \| Third Largest Customer
Product Information [Line Items]
Concentration risk percentage	20.80%
Accounts Receivable
Product Information [Line Items]
Concentration risk percentage	99.60%
Accounts Receivable \| Largest Customer
Product Information [Line Items]
Concentration risk percentage	61.30%
Accounts Receivable \| Second Largest Customer
Product Information [Line Items]
Concentration risk percentage	29.80%
Accounts Receivable \| Third Largest Customer
Product Information [Line Items]
Concentration risk percentage	8.50%

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
	Jan. 01, 2018	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Product Information [Line Items]
Cumulative adjustment to accumulated deficit		$ (1,392,748)				$ (1,165,470)				$ (1,392,748)	$ (1,165,470)
Product sales allowances		24,571				27,939				24,571	27,939
Cost of product sales		$ 9,392	$ 7,170	$ 9,005	$ 10,622	$ 15,874	$ 17,195	$ 13,588	$ 14,962	$ 36,189	$ 61,619	$ 27,512
Accounting Standards Update 2014-09
Product Information [Line Items]
Gross product sales	$ 2,900
Cost of product sales	200
Accounting Standards Update 2014-09 \| Product Sales Allowance
Product Information [Line Items]
Product sales allowances	1,100
Accounting Standards Update 2018-13
Product Information [Line Items]
Change in accounting principle, accounting standards update, adopted		true								true
Change in accounting principle, accounting standards update, immaterial effect		true								true
Accounting Standards Update 2016-13
Product Information [Line Items]
Change in accounting principle, accounting standards update, adopted		true								true
Change in accounting principle, accounting standards update, immaterial effect		true								true
Change in accounting principle, accounting standards update, adoption date		Jan. 01, 2020								Jan. 01, 2020
Cumulative Effect Period of Adoption Adjustment \| Accounting Standards Update 2014-09
Product Information [Line Items]
Cumulative adjustment to accumulated deficit	$ (1,600)
Leasehold Improvements
Product Information [Line Items]
Estimated useful lives										5 years

Summary of Significant Accounting Policies - Common Stock Equivalents Excluded From Computation of Net Loss Per Share (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement, Option
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Shares excluded (in shares)	18,912	16,665	15,265
Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Shares excluded (in shares)	603
Warrant
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Shares excluded (in shares)	220	508	640
Convertible Debt Securities
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Shares excluded (in shares)	9,510	8,960	8,473

Fair Value Measurements - Schedule of Financial Assets Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 103,353	$ 319,074
U.S. Treasury Bills and Government Agency Obligations
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	20,276	140,626
U.S. Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	11,547	80,170
Foreign Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	15,557	23,203
U.S. Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	13,997	32,801
Fair Value, Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total	208,491	390,972
Fair Value, Recurring \| Foreign Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	83,966	57,241
Fair Value, Recurring \| U.S. Treasury Bills and Government Agency Obligations
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	20,276	140,626
Fair Value, Recurring \| U.S. Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	11,547	80,170
Fair Value, Recurring \| Foreign Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	15,557	23,203
Fair Value, Recurring \| U.S. Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	27,996	32,801
Fair Value, Recurring \| Cash and Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and money market funds	49,149	56,931
Fair Value, Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total	49,149	197,557
Fair Value, Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| U.S. Treasury Bills and Government Agency Obligations
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities		140,626
Fair Value, Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Cash and Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and money market funds	49,149	56,931
Fair Value, Recurring \| Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total	159,342	193,415
Fair Value, Recurring \| Significant Other Observable Inputs (Level 2) \| Foreign Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	83,966	57,241
Fair Value, Recurring \| Significant Other Observable Inputs (Level 2) \| U.S. Treasury Bills and Government Agency Obligations
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	20,276
Fair Value, Recurring \| Significant Other Observable Inputs (Level 2) \| U.S. Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	11,547	80,170
Fair Value, Recurring \| Significant Other Observable Inputs (Level 2) \| Foreign Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	15,557	23,203
Fair Value, Recurring \| Significant Other Observable Inputs (Level 2) \| U.S. Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 27,996	$ 32,801

Fair Value Measurements - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Financial instruments transferred among fair value hierarchy levels	$ 0
Cash equivalents included of available-for-sale securities	55,900,000	$ 15,000,000.0
Available for sale securities with contractual maturities of three months to one year.	$ 103,400,000	279,700,000
Available for sale securities with contractual maturities greater than one year		$ 39,400,000

Balance Sheet Details - Summary of Short -Term Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale securities, amortized cost	$ 103,096	$ 318,989
Available-for-sale securities, gross unrealized gains	257	85
Available-for-sale securities	103,353	319,074
U.S. Treasury Bills and Government Agency Obligations
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale securities, amortized cost	20,110	140,567
Available-for-sale securities, gross unrealized gains	166	59
Available-for-sale securities	20,276	140,626
U.S. Corporate Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale securities, amortized cost	11,505	80,159
Available-for-sale securities, gross unrealized gains	42	11
Available-for-sale securities	11,547	80,170
Foreign Corporate Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale securities, amortized cost	15,508	23,188
Available-for-sale securities, gross unrealized gains	49	15
Available-for-sale securities	15,557	23,203
U.S. Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale securities, amortized cost	13,997	32,801
Available-for-sale securities	13,997	32,801
Foreign Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale securities, amortized cost	41,976	42,274
Available-for-sale securities	$ 41,976	$ 42,274

Balance Sheet Details - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt securities, impairment losses	$ 0	$ 0
Debt securities, available-for-sale, unrealized gain (loss)	172,000	172,000	$ (77,000)
Debt securities, available-for-sale, realized gain (loss)	0	8,000	0
Inventory	41,905,000	24,968,000
Depreciation and amortization	2,847,000	2,044,000	$ 1,513,000
Construction in Progress, Gross	14,100,000	13,500,000
SUSTOL
Inventory	4,100,000	1,500,000
Cost of product sales, charges	100,000	3,300,000
CINVANTI
Inventory	$ 37,800,000	$ 23,500,000

Balance Sheet Details - Schedule of Inventory (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Raw materials	$ 18,994	$ 6,635
Work in process	6,847	12,571
Finished goods	16,064	5,762
Total inventory	$ 41,905	$ 24,968

Balance Sheet Details - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 33,609	$ 27,643
Less: accumulated depreciation and amortization	(10,872)	(8,025)
Property and equipment, net	22,737	19,618
Scientific Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	29,135	24,603
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	878	206
Computer Equipment and Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	1,461	1,314
Furniture, Fixtures and Office Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 2,135	$ 1,520

Balance Sheet Details - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accrued payroll and employee liabilities
Accrued employee salaries and benefits	$ 1,691	$ 3,047
Accrued bonuses	8,479	9,545
Accrued vacation	3,427	2,656
Total accrued payroll and employee liabilities	13,597	15,248
Other accrued liabilities
Accrued product sales allowances	24,571	27,939
Accrued consulting and professional fees	3,450	7,742
Accrued accounts payable	104	310
Other accrued liabilities	244	544
Total other accrued liabilities	$ 28,369	$ 36,535

Revenue Recognition - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation Of Revenue [Line Items]
Net product sales	$ 20,605	$ 19,965	$ 22,668	$ 25,400	$ 35,083	$ 42,624	$ 36,659	$ 31,602	$ 88,638	$ 145,968	$ 77,474
CINVANTI
Disaggregation Of Revenue [Line Items]
Net product sales									87,800	132,200
SUSTOL
Disaggregation Of Revenue [Line Items]
Net product sales									$ 800	$ 13,800

- Definition

Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9038-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130545-203045

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130543-203045

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9031-108599

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 924
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-URI http://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856

+ Details

Revenue Recognition - Summary of Activity to Product Returns, Distributor Fees and Discounts, Rebates and Administrative Fees (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Product Information [Line Items]
Balance	$ 27,939
Provision	119,065
Payments/credits	(122,433)
Balance	24,571
Product Returns
Product Information [Line Items]
Balance	2,351
Provision	498
Payments/credits	(145)
Balance	2,704
Distributor Fees
Product Information [Line Items]
Balance	3,999
Provision	15,964
Payments/credits	(16,033)
Balance	3,930
Discounts, Rebates and Administrative Fees
Product Information [Line Items]
Balance	21,589
Provision	102,603
Payments/credits	(106,255)
Balance	$ 17,937

Commitments and Contingencies - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) ft²	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Lessee Lease Description [Line Items]
Operating lease, rent expense \| $	$ 3.9	$ 3.1	$ 3.2
San Diego, California
Lessee Lease Description [Line Items]
Area of real estate property	73,328
Lease expiration date	Dec. 31, 2025
Lessee, operating lease, renewal term	5 years
Lessee, operating lease, existence of option to extend	true
Operating lease cash payments \| $	$ 3.6
Redwood City, California
Lessee Lease Description [Line Items]
Area of real estate property	26,067
Lease expiration date	2019-05
Sublease expiration date	2019-05
Jersey City, New Jersey
Lessee Lease Description [Line Items]
Area of real estate property	1,898
Lease expiration date	2019-12

Commitments and Contingencies - Summary of Future Minimum Lease Payments (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2021	$ 3,942
2022	4,058
2023	4,178
2024	4,274
2025	4,379
Total future minimum lease payments	20,831
Less: discount	(3,273)
Total lease liabilities	$ 17,558

Reorganization - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Oct. 31, 2020	Dec. 31, 2020
Restructuring charges, total	$ 5.6	$ 5.6
Research And Development Expense
Restructuring charges, total		1.2
General and Administrative Expense
Restructuring charges, total		3.7
Sales And Marketing Expense
Restructuring charges, total		0.7
Employee Severance
Restructuring charges, total	2.5
Payments for restructuring charges		$ 2.4
Accelerated Non-Cash Stock Option Expense
Restructuring charges, total	$ 3.1

Secured Notes to Related Party - Additional Information (Details)				1 Months Ended			12 Months Ended
	Aug. 05, 2016 USD ($)	Aug. 02, 2016 USD ($) shares	Jul. 29, 2011 shares	Aug. 31, 2018 USD ($)	Aug. 31, 2016 USD ($)	Apr. 30, 2011 USD ($) Day shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Debt Instrument [Line Items]
Proceeds from convertible debt						$ 4,300,000
Amortization of debt discount							$ 1,429,000	$ 1,050,000	$ 890,000
Debt instrument, convertible, number shares of equity instruments \| shares							9,500,000
Convertible Notes
Debt Instrument [Line Items]
Convertible debt issuable in connection with private placement						$ 4,500,000
Debt instrument, interest rate						6.00%
Debt instrument, maturity date						May 02, 2021
Debt instrument conversion ratio multiple of principal						$ 1,000
Beneficial ownership after conversion						9.99%
Notice period associated with beneficial ownership percentage limitation convertible notes \| Day						61
Common shares registered for resale in connection with convertible notes \| shares			3,500,000
Debt instrument, term						10 years
Paid-in-kind interest							$ 400,000
Debt instrument, additional debt discount							400,000
Interest expense, debt, excluding amortization							400,000	400,000	400,000
Amortization of debt discount							1,400,000	$ 1,100,000	900,000
Carrying value of debt							7,100,000
Debt instrument, face amount							7,600,000
Debt instrument, unamortized discount, total							$ 500,000
Convertible Notes \| Common Stock
Debt Instrument [Line Items]
Debt instrument, number of shares issued for convertible notes \| shares						1,250
Term Loan \| Tang Capital
Debt Instrument [Line Items]
Debt instrument, interest rate					8.00%
Debt instrument, term					2 years
Carrying value of debt									0
Debt agreement, maximum borrowing capacity					$ 100,000,000.0
Proceeds from issuance of long-term debt, total	$ 50,000,000.0
Proceeds from issuance of long-term debt, subject to achievement of corporate milestone		$ 50,000,000.0
Debt instrument, fee amount		$ 0
Debt instrument, number of warrants \| shares		0
Debt instrument, convertible, beneficial conversion feature		$ 0
Interest expense									$ 1,200,000
Debt outstanding principal paid				$ 25,000,000.0
Debt accrued interest paid				$ 200,000

Stockholders' Equity - Additional Information (Details) - USD ($)	1 Months Ended													12 Months Ended
	Oct. 31, 2019	Jun. 30, 2019	Jun. 30, 2018	Apr. 30, 2018	Jun. 30, 2017	Jun. 30, 2016	May 31, 2015	Jun. 30, 2014	May 31, 2014	Jun. 30, 2011	May 31, 2010	May 31, 2009	Dec. 31, 2007	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 1997
Class Of Stock [Line Items]
Proceeds from issuance of common stock	$ 162,200,000		$ 194,400,000	$ 168,700,000											$ 162,151,000	$ 363,128,000
Class of warrant or right, number of securities called by warrants or rights														220,164
Common stock, shares, issued, total														91,310,000	90,304,000
Common stock, capital shares reserved for future issuance														30,997,847
Share-based compensation arrangement by share-based payment award, number of shares available for grant														1,575,955
Share-based compensation arrangement by share-based payment award, expiration period														10 years
Share-based compensation arrangement by share-based payment award, award vesting period														4 years
Share-based compensation arrangement by share-based payment award, options, exercisable, weighted average remaining contractual term														5 years 8 months 12 days
Share-based compensation arrangement by share-based payment award, options, exercises in period, intrinsic value														$ 3,200	$ 25,000.0
Share-based compensation arrangement by share-based payment award, options, outstanding, intrinsic value														$ 69,100	$ 56,300
Common stock future issuance on exercise of outstanding options and vesting of outstanding restricted stock units granted														19,515,270
Total unrecognized compensation cost related to non-vested, stock-based payment awards														$ 116,100,000
Total unrecognized compensation cost, expect to recognize over weighted average period														2 years 9 months 18 days
Stock Option and RSUs
Class Of Stock [Line Items]
Share-based compensation arrangements by share-based payment award, options, exercises in period, weighted average exercise price														$ 12.41	$ 11.18	$ 11.97
Share-based compensation arrangement by share-based payment award, options, forfeitures in period														922,578
Share-based compensation arrangements by share-based payment award, options, forfeitures in period, weighted average exercise price														$ 22.76
Share-based Payment Arrangement, Option
Class Of Stock [Line Items]
Share-based compensation arrangement by share-based payment award, options, expirations in period														342,293
Share-based compensation arrangements by share-based payment award, options, expirations in period, weighted average exercise price														$ 23.04
Expected life														6 years	6 years	6 years
Restricted Stock Units
Class Of Stock [Line Items]
Share-based compensation arrangement by share-based payment award, award vesting period														4 years
Employee Stock Purchase Plan
Class Of Stock [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares authorized																		10,000
Share-based compensation arrangement by share-based payment award, number of additional shares authorized		300,000			200,000	100,000	100,000		25,000	25,000		10,000	5,000	775,000
Share-based compensation arrangement by share-based payment award maximum employee earnings with held to purchase common stock percent														10.00%
Share-based compensation arrangement by share-based payment award discount on stock price														85.00%
Share-based compensation arrangement by share-based payment award, shares issued in period														193,841	125,727	71,499
Share-based compensation arrangements by share-based payment award, options, exercises in period, weighted average exercise price														$ 11.95	$ 16.77	$ 16.48
Common stock, shares, issued, total														598,750
Common stock, capital shares reserved for future issuance														176,250
Share-based compensation arrangement by share-based payment award, options, grants in period, weighted average grant date fair value														$ 9.76	14.70	17.24
Share-based compensation arrangement by share-based payment award, per share weighted-average fair value price of shares purchased														$ 5.18	$ 5.94	$ 9.95
Expected life														6 months
Equity Incentive Plan 2007
Class Of Stock [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares authorized													150,000
Share-based compensation arrangement by share-based payment award, number of additional shares authorized		7,000,000			5,000,000	3,000,000	4,300,000		1,750,000	4,500,000	100,000			25,800,000
Share-based compensation arrangement by share-based payment award, number of shares available for grant														1,575,955
Pre-funded Warrants
Class Of Stock [Line Items]
Class of warrant or right, number of securities called by warrants or rights								600,000
Class of warrant or right, exercise price of warrants or rights								$ 0.01
Class of warrant or right, expiration date								Jun. 30, 2021
Class of warrant or right, exercised during period														267,870	132,130		4,426
Proceeds from issuance of warrants														$ 2,679,000	$ 1,321,000		$ 0
Class of warrant or right, outstanding														195,574
Common Stock
Class Of Stock [Line Items]
Number of shares issued	9,900,000		5,100,000	6,900,000											9,857,000	11,963,000
Share price	$ 17.50		$ 39.50	$ 26.00
Payments of stock issuance costs	$ 10,300,000		$ 5,600,000	$ 10,700,000
Issuance of common stock on exercise of warrants (in shares)														267,000	132,000
Common Stock \| Pre-funded Warrants
Class Of Stock [Line Items]
Issuance of common stock on exercise of warrants (in shares)														267,870	132,130		4,423

Stockholders' Equity - Summary of Common Stock Reserved for Future Issuance (Details)	Dec. 31, 2020 shares
Stockholders Equity Note [Abstract]
Stock options outstanding	18,912,529
Restricted stock units outstanding	602,741
Stock options available for grant	1,575,955
Employee Stock Purchase Plan	176,250
Warrants outstanding	220,164
Shares of common stock underlying Convertible Notes outstanding (see Note 8)	9,510,208
Total shares reserved for future issuance	30,997,847

Stockholders' Equity - Summary of Stock Option Plan Activity (Including Restricted Stock Units) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares outstanding	18,912,529
Stock Option and RSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares outstanding	16,664,640	15,264,607	13,462,964
Number of shares granted	4,659,942	4,933,480	4,052,011
Number of shares exercised	(544,441)	(1,983,221)	(1,529,509)
Number of shares cancelled	(1,264,871)	(1,550,226)	(720,859)
Number of shares outstanding	19,515,270	16,664,640	15,264,607
Number of shares outstanding, weighted average exercise price	$ 20.47	$ 18.33	$ 15.03
Number of shares granted, weighted average exercise price	13.95	24.21	26.83
Number of shares exercised, weighted average exercise price	12.41	11.18	11.97
Number of shares cancelled, weighted average exercise price	22.84	23.26	17.98
Number of shares outstanding, weighted average exercise price	$ 18.98	$ 20.47	$ 18.33

Stockholders' Equity - Schedule of Options Exercisable, Vested or Expected to Vest (Details) - $ / shares	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Equity [Abstract]
Options exercisable at end of year	10,237,202	7,436,379	6,523,093
Options vested or expected to vest	18,179,553	15,962,432	14,449,017
Options exercisable at end of year, weighted average exercise price	$ 18.74	$ 17.02	$ 14.83
Options vested or expected to vest, weighted average exercise price	$ 19.58	$ 20.31	$ 18.11

Stockholders' Equity - Schedule of Exercise Prices And Weighted-average Remaining Contractual Lives For Options Outstanding (Details)	12 Months Ended
	Dec. 31, 2020 $ / shares shares
Options Outstanding (in shares) \| shares	18,912,529
Weighted- Average Remaining Contractual Life (Year)	7 years 2 months 15 days
Weighted- Average Exercise Price (in dollars per share)	$ 19.59
Options Exercisable (in shares) \| shares	10,237,202
Weighted- Average Exercise Price of Options Exercisable	$ 18.74
Exercise Price Range 1
Options Outstanding (in shares) \| shares	2,700,473
Range of Exercise Prices, Lower Limit (in dollars per share)	$ 5.20
Range of Exercise Prices, Upper Limit (in dollars per share)	$ 13.00
Weighted- Average Remaining Contractual Life (Year)	3 years 11 months 19 days
Weighted- Average Exercise Price (in dollars per share)	$ 10.14
Options Exercisable (in shares) \| shares	2,691,327
Weighted- Average Exercise Price of Options Exercisable	$ 10.14
Exercise Price Range 2
Options Outstanding (in shares) \| shares	800,371
Range of Exercise Prices, Lower Limit (in dollars per share)	$ 13.05
Range of Exercise Prices, Upper Limit (in dollars per share)	$ 15.55
Weighted- Average Remaining Contractual Life (Year)	6 years 1 month 17 days
Weighted- Average Exercise Price (in dollars per share)	$ 14.31
Options Exercisable (in shares) \| shares	655,173
Weighted- Average Exercise Price of Options Exercisable	$ 14.22
Exercise Price Range 3
Options Outstanding (in shares) \| shares	3,582,407
Exercise Prices	$ 15.72
Weighted- Average Remaining Contractual Life (Year)	9 years 9 months
Weighted- Average Exercise Price (in dollars per share)	$ 15.72
Options Exercisable (in shares) \| shares	149,197
Weighted- Average Exercise Price of Options Exercisable	$ 15.72
Exercise Price Range 4
Options Outstanding (in shares) \| shares	2,838,033
Range of Exercise Prices, Lower Limit (in dollars per share)	$ 15.78
Range of Exercise Prices, Upper Limit (in dollars per share)	$ 17.89
Weighted- Average Remaining Contractual Life (Year)	6 years 1 month 6 days
Weighted- Average Exercise Price (in dollars per share)	$ 16.87
Options Exercisable (in shares) \| shares	2,348,090
Weighted- Average Exercise Price of Options Exercisable	$ 16.84
Exercise Price Range 5
Options Outstanding (in shares) \| shares	3,688,255
Range of Exercise Prices, Lower Limit (in dollars per share)	$ 18.00
Range of Exercise Prices, Upper Limit (in dollars per share)	$ 24.97
Weighted- Average Remaining Contractual Life (Year)	7 years 1 month 24 days
Weighted- Average Exercise Price (in dollars per share)	$ 22.97
Options Exercisable (in shares) \| shares	2,036,430
Weighted- Average Exercise Price of Options Exercisable	$ 23.10
Exercise Price Range 6
Options Outstanding (in shares) \| shares	3,498,912
Exercise Prices	$ 25.02
Weighted- Average Remaining Contractual Life (Year)	8 years 7 months 17 days
Weighted- Average Exercise Price (in dollars per share)	$ 25.02
Options Exercisable (in shares) \| shares	1,010,859
Weighted- Average Exercise Price of Options Exercisable	$ 25.02
Exercise Price Range 7
Options Outstanding (in shares) \| shares	1,804,078
Range of Exercise Prices, Lower Limit (in dollars per share)	$ 25.06
Range of Exercise Prices, Upper Limit (in dollars per share)	$ 39.00
Weighted- Average Remaining Contractual Life (Year)	6 years 7 months 20 days
Weighted- Average Exercise Price (in dollars per share)	$ 30.58
Options Exercisable (in shares) \| shares	1,346,126
Weighted- Average Exercise Price of Options Exercisable	$ 30.43

Stockholders' Equity - Summary of Stock-Based Compensation Expense related to Stock-Based Payment Awards (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 50,218	$ 51,411	$ 33,367
Research and Development Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	20,731	19,202	13,689
General and Administrative Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	15,601	13,564	9,630
Sales and Marketing Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 13,886	$ 18,645	$ 10,048

Stockholders' Equity - Summary of Fair Value of Option Grant and ESPP Purchase Right on Grant Date Using Black-Scholes Option Pricing Model (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement, Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	0.50%	1.80%	2.80%
Dividend yield	0.00%	0.00%	0.00%
Volatility	69.40%	66.50%	70.40%
Expected life	6 years	6 years	6 years
Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	0.10%	1.90%	2.40%
Dividend yield	0.00%	0.00%	0.00%
Volatility	67.70%	52.10%	59.70%
Expected life	6 months	6 months	6 months

Income Taxes - Schedule of Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Tax at statutory federal rate	$ (47,728)	$ (42,997)	$ (37,557)
State tax, net of federal benefit	(8,218)	(9,823)	(6,527)
Research and development credits	(4,327)	(4,855)	(4,775)
Stock-based compensation expense	4,675	2,906	(2,059)
Non-deductible compensation	1,455	4,720	901
Change in valuation allowance	53,621	49,479	50,834
Other	522	570	(817)
Provision for income taxes	$ 0	$ 0	$ 0

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carryforward	$ 251,971	$ 210,301
Research and development credits	49,683	42,490
Stock-based compensation	20,211	15,628
Lease liabilities	4,330	3,487
Other	3,777	3,818
Total gross deferred tax assets	329,972	275,724
Deferred tax liabilities:
Right-of-use lease assets	(4,014)	(3,385)
Total gross deferred tax liabilities	(4,014)	(3,385)
Valuation allowance	$ (325,958)	$ (272,339)

Income Taxes - Additional Information (Details) - USD ($)			12 Months Ended
	Jun. 29, 2020	Mar. 27, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards, Research			$ 49,683,000	$ 42,490,000
Unrecognized Tax Benefits, Ending Balance			7,406,000	$ 4,784,000	$ 2,385,000	$ 120,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total			0
Net operating loss carryback period		5 years
Suspension of taxable income limitation percentage for operating loss carryforward		80.00%
California Franchise Tax Board \| Minimum
Operating Loss Carryforwards [Line Items]
Adjusted gross income for disallowance of net operating loss deductions	$ 1,000,000
California Franchise Tax Board \| Maximum
Operating Loss Carryforwards [Line Items]
Business credit offset amount	$ 5,000,000
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Total			1,000,000,000.0
Expiring Operating Loss Carryforwards			$ 549,700,000
Net operating loss carryforwards expiration year			2021
Indefinite Operating Loss Carryforwards			$ 492,000,000.0
Taxable income limitation percentage for operating loss carryforward			80.00%
Deferred Tax Assets, Tax Credit Carryforwards, Research			$ 39,400,000
Research and development credit carryforwards expiration year			2022
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards expiration year			2028
Deferred Tax Assets, Tax Credit Carryforwards, Research			$ 18,100,000
Research and development credit carryforwards expiration year			2023
State and Local Jurisdiction \| California Franchise Tax Board
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Total			$ 111,900,000
State and Local Jurisdiction \| Other State Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Total			$ 515,500,000

Income Taxes - Summary of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Balance at beginning of year	$ 4,784	$ 2,385	$ 120
Additions for tax positions of prior years	341	147
Additions based on tax positions related to current year	2,281	2,252	2,265
Balance at end of year	$ 7,406	$ 4,784	$ 2,385

Other Income (Expense), Net - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other income (expense)	$ (847)	$ 158	$ 1,804
Disgorgement of Short-Swing Profits from the Sale of Common Stock
Other income (expense)			$ 1,900

Employee Benefit Plan - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, employer matching contribution, percent of match	50.00%	50.00%	50.00%
Defined contribution plan, maximum annual contributions by employer per employee, amount	$ 8,550	$ 8,400	$ 8,250
Defined contribution plan, cost	$ 1,100,000	$ 1,000,000.0	$ 700,000
Maximum
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, employer matching contribution, percent of employees' gross pay	3.00%	3.00%	3.00%

Summary of Quarterly Consolidated Financial Data (Unaudited) - Summary of Unaudited Quarterly Results of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues:
Net product sales	$ 20,605	$ 19,965	$ 22,668	$ 25,400	$ 35,083	$ 42,624	$ 36,659	$ 31,602	$ 88,638	$ 145,968	$ 77,474
Cost of product sales	(9,392)	(7,170)	(9,005)	(10,622)	(15,874)	(17,195)	(13,588)	(14,962)	(36,189)	(61,619)	(27,512)
Gross Profit	11,213	12,795	13,663	14,778	19,209	25,429	23,071	16,640
Operating expenses:
Research and development	44,453	49,182	44,004	36,894	48,277	34,708	41,425	42,972	174,533	167,382	140,032
General and administrative	12,503	9,482	9,819	10,422	9,874	8,597	9,778	9,648	42,226	37,897	29,263
Sales and marketing	15,553	12,515	15,589	20,196	20,420	16,977	23,647	28,720	63,853	89,764	64,604
Loss from operations	(61,296)	(58,384)	(55,749)	(52,734)	(59,362)	(34,853)	(51,779)	(64,700)	(228,163)	(210,694)	(183,937)
Other income (expense), net	(985)	156	559	1,155	1,442	1,258	1,557	1,688	885	5,945	5,097
Net loss	$ (62,281)	$ (58,228)	$ (55,190)	$ (51,579)	$ (57,920)	$ (33,595)	$ (50,222)	$ (63,012)	$ (227,278)	$ (204,749)	$ (178,840)
Basic and diluted net loss per share	$ (0.68)	$ (0.64)	$ (0.61)	$ (0.57)	$ (0.65)	$ (0.42)	$ (0.63)	$ (0.80)	$ (2.50)	$ (2.50)	$ (2.44)