Global Blood Therapeutics (GBT) 10-Q 4 Nov 21 2021 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2021	Oct. 29, 2021
Cover [Abstract]
Document Type	10-Q
Document Period End Date	Sep. 30, 2021
Entity Registrant Name	Global Blood Therapeutics, Inc.
Entity Filer Category	Large Accelerated Filer
Trading Symbol	GBT
Entity Emerging Growth Company	false
Entity Small Business	false
Document Transition Report	false
Entity Common Stock, Shares Outstanding		64,445,267
Document Quarterly Report	true
Entity Interactive Data Current	Yes
Entity Current Reporting Status	Yes
Entity File Number	001-37539
Entity Tax Identification Number	27-4825712
Entity Shell Company	false
Entity Address, Address Line One	181 Oyster Point Boulevard
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	CA
City Area Code	650
Local Phone Number	741-7700
Entity Address, Postal Zip Code	94080
Title of 12(b) Security	Common Stock
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001629137
Current Fiscal Year End Date	--12-31

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 382,869	$ 494,766
Short-term marketable securities	3,205	66,126
Accounts receivable, net	23,894	17,500
Inventories	51,512	40,223
Prepaid expenses and other current assets	27,384	13,548
Total current assets	488,864	632,163
Long-term marketable securities	30,692
Property and equipment, net	35,415	37,882
Operating Lease Right Of Use Asset	48,732	50,722
Restricted cash	2,451	2,436
Other assets, noncurrent	1,524	799
Total assets	607,678	724,002
Current liabilities:
Accounts payable	8,642	19,078
Accrued liabilities	37,297	31,133
Accrued compensation	22,665	23,985
Operating lease liabilities, current	5,454	4,836
Total current liabilities	74,058	79,032
Long-term debt	149,508	148,815
Operating Lease, Liability, Noncurrent	74,990	79,176
Other liabilities, noncurrent	822	822
Total liabilities	299,378	307,845
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.001 par value, 5,000,000 shares authorized as of September 30, 2021 (unaudited) and December 31, 2020; no shares issued and outstanding
Common stock, $0.001 par value, 150,000,000 shares authorized as of September 30, 2021 (unaudited) and December 31, 2020, respectively; 64,387,670 and 61,898,090 shares issued and outstanding as of September 30, 2021 (unaudited) and December 31, 2020, respectively	64	62
Additional paid-in capital	1,509,994	1,402,262
Accumulated other comprehensive loss	221	302
Accumulated deficit	(1,201,979)	(986,469)
Total stockholders' equity	308,300	416,157
Total liabilities and stockholders' equity	$ 607,678	$ 724,002

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	64,387,670	61,898,090
Common stock, shares outstanding	64,387,670	61,898,090

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenues [Abstract]
Product sales, net	$ 52,052	$ 36,889	$ 138,650	$ 82,508
Costs and operating expenses:
Cost of sales	830	513	2,162	1,025
Research and development	50,529	40,196	153,170	114,054
Selling, general and administrative	67,987	54,491	188,046	151,227
Total costs and operating expenses	119,346	95,200	343,378	266,306
Loss from operations	(67,294)	(58,311)	(204,728)	(183,798)
Other income (expense):
Interest income	85	881	578	5,251
Interest expense	(3,709)	(2,291)	(11,075)	(6,887)
Other expenses, net	(70)	(160)	(285)	(313)
Total other income (expense), net	(3,694)	(1,570)	(10,782)	(1,949)
Net loss	(70,988)	(59,881)	(215,510)	(185,747)
Other comprehensive loss:
Net unrealized gain on marketable securities, net of tax	(42)	(507)	(301)	(35)
Cumulative translation adjustment	(39)	0	220	0
Comprehensive loss	$ (71,069)	$ (60,388)	$ (215,591)	$ (185,782)
Basic and diluted net loss per common share	$ (1.13)	$ (0.97)	$ (3.45)	$ (3.04)
Weighted-average number of shares used in computing basic and diluted net loss per common share	62,925,081	61,573,877	62,449,207	61,160,984

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income [Member]	Accumulated Deficit [Member]
Beginning Balance at Dec. 31, 2019	$ 578,694	$ 61	$ 1,316,795	$ 754	$ (738,916)
Beginning Balance, Shares at Dec. 31, 2019		60,644,380
Issuance of common stock upon exercise of stock options	967		967
Issuance of common stock upon exercise of stock options, Shares		33,937
Issuance of common stock upon vesting of restricted share units, net of shares withheld for employee taxes	(2,099)		(2,099)
Issuance of common stock upon vesting of restricted share units, net of shares withheld for employee taxes, Shares		160,594
Issuance of common stock pursuant to ESPP purchases	1,870		1,870
Issuance of common stock pursuant to ESPP purchases, Shares		47,460
Stock-based compensation	16,705		16,705
Net unrealized gain (loss) on marketable securities	461			461
Net loss	(73,026)				(73,026)
Ending Balance at Mar. 31, 2020	523,572	$ 61	1,334,238	1,215	(811,942)
Ending Balance, Shares at Mar. 31, 2020		60,886,371
Beginning Balance at Dec. 31, 2019	578,694	$ 61	1,316,795	754	(738,916)
Beginning Balance, Shares at Dec. 31, 2019		60,644,380
Cumulative translation adjustment	0
Net loss	(185,747)
Ending Balance at Sep. 30, 2020	457,655	$ 61	1,381,537	720	(924,663)
Ending Balance, Shares at Sep. 30, 2020		61,756,658
Beginning Balance at Mar. 31, 2020	523,572	$ 61	1,334,238	1,215	(811,942)
Beginning Balance, Shares at Mar. 31, 2020		60,886,371
Issuance of common stock upon exercise of stock options	8,018		8,018
Issuance of common stock upon exercise of stock options, Shares		334,454
Issuance of common stock upon vesting of restricted share units, net of shares withheld for employee taxes	(74)		(74)
Issuance of common stock upon vesting of restricted share units, net of shares withheld for employee taxes, Shares		110,162
Stock-based compensation	17,128		17,128
Net unrealized gain (loss) on marketable securities	12			12
Net loss	(52,840)				(52,840)
Ending Balance at Jun. 30, 2020	495,816	$ 61	1,359,310	1,227	(864,782)
Ending Balance, Shares at Jun. 30, 2020		61,330,987
Issuance of common stock upon exercise of stock options	3,312		3,312
Issuance of common stock upon exercise of stock options, Shares		121,619
Issuance of common stock upon vesting of restricted share units, net of shares withheld for employee taxes	(2,990)		(2,990)
Issuance of common stock upon vesting of restricted share units, net of shares withheld for employee taxes, Shares		253,447
Issuance of common stock pursuant to ESPP purchases	2,266		2,266
Issuance of common stock pursuant to ESPP purchases, Shares		50,605
Stock-based compensation	19,639		19,639
Net unrealized gain (loss) on marketable securities	(507)			(507)
Cumulative translation adjustment	0
Net loss	(59,881)				(59,881)
Ending Balance at Sep. 30, 2020	457,655	$ 61	1,381,537	720	(924,663)
Ending Balance, Shares at Sep. 30, 2020		61,756,658
Beginning Balance at Dec. 31, 2020	416,157	$ 62	1,402,262	302	(986,469)
Beginning Balance, Shares at Dec. 31, 2020		61,898,090
Issuance of common stock upon exercise of stock options	1,110		1,110
Issuance of common stock upon exercise of stock options, Shares		47,763
Issuance of common stock upon vesting of restricted share units, net of shares withheld for employee taxes	(1,897)		(1,897)
Issuance of common stock upon vesting of restricted share units, net of shares withheld for employee taxes, Shares		229,087
Issuance of common stock pursuant to ESPP purchases	2,558		2,558
Issuance of common stock pursuant to ESPP purchases, Shares		65,110
Stock-based compensation	20,378		20,378
Net unrealized gain (loss) on marketable securities	(181)			(181)
Net loss	(74,930)				(74,930)
Ending Balance at Mar. 31, 2021	363,195	$ 62	1,424,411	121	(1,061,399)
Ending Balance, Shares at Mar. 31, 2021		62,240,050
Beginning Balance at Dec. 31, 2020	$ 416,157	$ 62	1,402,262	302	(986,469)
Beginning Balance, Shares at Dec. 31, 2020		61,898,090
Issuance of common stock upon exercise of stock options, Shares	97,891
Issuance of common stock upon at-the-market financing, Shares	1,601,884
Cumulative translation adjustment	$ 220
Net loss	(215,510)
Ending Balance at Sep. 30, 2021	308,300	$ 64	1,509,994	221	(1,201,979)
Ending Balance, Shares at Sep. 30, 2021		64,387,670
Beginning Balance at Mar. 31, 2021	363,195	$ 62	1,424,411	121	(1,061,399)
Beginning Balance, Shares at Mar. 31, 2021		62,240,050
Issuance of common stock upon exercise of stock options	403		403
Issuance of common stock upon exercise of stock options, Shares		28,575
Issuance of common stock upon vesting of restricted share units, net of shares withheld for employee taxes	(65)		(65)
Issuance of common stock upon vesting of restricted share units, net of shares withheld for employee taxes, Shares		110,493
Stock-based compensation	21,644		21,644
Net unrealized gain (loss) on marketable securities	(78)			(78)
Cumulative translation adjustment	259			259
Net loss	(69,592)				(69,592)
Ending Balance at Jun. 30, 2021	315,766	$ 62	1,446,393	302	(1,130,991)
Ending Balance, Shares at Jun. 30, 2021		62,379,118
Issuance of common stock upon exercise of stock options	429		429
Issuance of common stock upon exercise of stock options, Shares		21,553
Issuance of common stock upon vesting of restricted share units, net of shares withheld for employee taxes	(1,094)		(1,094)
Issuance of common stock upon vesting of restricted share units, net of shares withheld for employee taxes, Shares		315,627
Issuance of common stock pursuant to ESPP purchases	1,695		1,695
Issuance of common stock pursuant to ESPP purchases, Shares		69,488
Issuance of common stock upon at-the-market financing	44,073	$ 2	44,071
Issuance of common stock upon at-the-market financing, Shares		1,601,884
Stock-based compensation	18,500		18,500
Net unrealized gain (loss) on marketable securities	(42)			(42)
Cumulative translation adjustment	(39)			(39)
Net loss	(70,988)				(70,988)
Ending Balance at Sep. 30, 2021	$ 308,300	$ 64	$ 1,509,994	$ 221	$ (1,201,979)
Ending Balance, Shares at Sep. 30, 2021		64,387,670

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($)	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (215,510,000)	$ (185,747,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	4,408,000	6,925,000
Amortization (accretion) of premium (discount) on marketable securities	127,000	37,000
Non-cash interest expense	716,000	1,243,000
Operating Lease, Right-of-Use Asset, Amortization Expense	1,990,000	901,000
Stock-based compensation	59,264,000	52,100,000
Changes in operating assets and liabilities:
Accounts receivable	(6,394,000)	(11,493,000)
Inventories	(9,903,000)	(30,853,000)
Prepaid expenses and other assets	(14,570,000)	(1,764,000)
Accounts payable	(10,291,000)	(2,821,000)
Accrued liabilities	6,164,000	2,299,000
Accrued compensation	(1,320,000)	375,000
Other liabilities, current	0	(651,000)
Operating lease liabilities	(3,568,000)	1,309,000
Other liabilities, noncurrent		1,344,000
Net cash used in operating activities	(188,887,000)	(166,796,000)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property and equipment	(2,180,000)	(4,190,000)
Purchase of marketable securities	(30,695,000)	(57,936,000)
Maturities of marketable securities	62,496,000	333,828,000
Net cash provided by investing activities	29,621,000	271,702,000
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock upon at-the-market financing, net of issuance cost	44,073,000
Proceeds from issuance of common stock in settlement of employee stock purchase plan and exercise of stock options	6,194,000	16,574,000
Payments of debt issuance costs	(49,000)	(130,000)
Tax paid related to net share settlement of equity awards	(3,054,000)	(5,163,000)
Net cash provided by financing activities	47,164,000	11,281,000
Effect of exchange rate changes on cash and cash equivalents	220,000
Net (decrease) increase in cash, cash equivalents and restricted cash	(111,882,000)	116,187,000
Cash, cash equivalents and restricted cash at beginning of period	497,202,000	304,632,000
Cash, cash equivalents and restricted cash at end of period	385,320,000	420,819,000
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid for interest	10,238,000	5,144,000
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING INFORMATION:
Leasehold improvements paid for by landlord		10,709,000
Accrued purchase of property and equipment	(119,000)	3,943,000
Accrued issuance costs	(26,000)	(52,000)
Operating lease liabilities arising from obtaining right-of-use-assets		205,000
RECONCILIATION OF CASH, CASH EQUIVALENTS, AND RESTRICTED CASH TO THE CONDENSED CONSOLIDATED BALANCE SHEETS
Cash and cash equivalents	382,869,000	418,402,000
Restricted cash	2,451,000	2,417,000
Total cash and cash equivalents and restricted cash	$ 385,320,000	$ 420,819,000

Organization

Organization	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	1. Organization Global Blood Therapeutics, Inc., or the Company, we, us, or our, was incorporated in Delaware in February 2011 and commenced operations in May 2012. We are a biopharmaceutical company dedicated to the discovery, development and delivery of life-changing treatments that provide hope to underserved patient communities. In late November 2019, we received U.S. Food and Drug Administration, or FDA, accelerated approval for our first medicine, Oxbryta ® (voxelotor) tablets for the treatment of sickle cell disease, or SCD, in adults and children 12 years of age and older. In early December 2019, we began to make Oxbryta available to patients through our specialty pharmacy partner network. Our principal operations are based in South San Francisco, California, and we operate in one segment. Need for Additional Capital In the course of our development activities, we have sustained operating losses and we expect such losses to continue over the next several years. Our ultimate success depends on the outcome of our commercialization of Oxbryta and research and development activities. Since our inception through September 30, 2021 , we have incurred cumulative net losses of $ 1.2 billion. We expect to incur additional losses for the foreseeable future to commercialize Oxbryta and conduct product research and development, and expect to potentially raise additional capital to fully implement our business plan. If needed, we intend to raise such capital through borrowings, the issuance of additional equity, and potentially through strategic alliances with partner companies or other transactions. However, if such financing is not available at adequate levels, we will need to re-evaluate our operating plans. We believe that our existing cash and cash equivalents and marketable securities will be sufficient to fund our cash requirements for at least 12 months subsequent to the issuance of these financial statements.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Preparation and Presentation of Financial Information The accompanying unaudited interim condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or U.S. GAAP, and applicable rules and regulations of the Securities and Exchange Commission, or SEC, regarding interim financial reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP have been condensed or omitted, and, accordingly, the balance sheet as of December 31, 2020, has been derived from audited consolidated financial statements at that date but does not include all of the information required by U.S. GAAP for complete financial statements. These unaudited interim condensed consolidated financial statements have been prepared on the same basis as our annual consolidated financial statements and, in the opinion of management, reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair presentation of our financial information. The results of operations for the nine months ended September 30, 2021, are not necessarily indicative of the results to be expected for the year ending December 31, 2021, or for any other interim period or for any other future year. The accompanying unaudited interim condensed consolidated financial statements and related financial information should be read in conjunction with the audited financial statements and the related notes thereto for the year ended December 31, 2020, included in our Annual Report on Form 10-K, filed with the SEC on February 24, 2021. Use of Estimates The preparation of the accompanying unaudited interim condensed consolidated financial statements in accordance with U.S. GAAP requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of variable consideration and costs and expenses during the reporting period. We base our estimates and assumptions on historical experience when available and on various factors that we believe to be reasonable under the circumstances. We evaluate our estimates and assumptions on an ongoing basis. Our actual results could differ from these estimates under different assumptions or conditions. Concentration of Risk Credit Risk We invest in a variety of financial instruments and, by our Board approved investment policy, limit the amount of credit exposure with any one issuer, industry or geographic area for investments other than instruments backed by the U.S. federal government. Major Customers We have entered into distribution agreements with certain limited specialty pharmacies and specialty distributors. For the nine months ended September 30, 2021 , our two largest customers represented approximately 84 % of our product revenue and approximately 76 % of our accounts receivable balance at September 30, 2021. Major Suppliers We do not currently have any of our own manufacturing facilities, and, therefore, depend on an outsourced manufacturing strategy for the production of Oxbryta for commercial use and for the production of our product candidates for clinical trials. We have contracts in place with third-party manufacturers that are approved for the commercial production of Oxbryta and third-party suppliers that are approved for Oxbryta’s active pharmaceutical ingredient. Although there are potential sources of supply other than our existing manufacturers and suppliers, any new supplier would be required to qualify under applicable regulatory requirements. Principles of Consolidation The accompanying unaudited interim condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany transactions and balances have been eliminated upon consolidation. Significant Accounting Policies Except as noted below, there have been no material revisions in our significant accounting policies described in Note 2 to the consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2020 . Accounting Pronouncements Adopted In December 2019, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, No. 2019-12, Income Taxes (Topic 740), Simplifying the Accounting for Income Taxes . The guidance eliminates 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. It also clarifies and simplifies other aspects of the accounting for income taxes. ASU 2019-12 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020, and the applicable amendments will be applied on a prospective basis. We adopted ASU No. 2019-12 in the first quarter of 2021 and applied the guidance prospectively. The only aspect of ASU 2019-12 that is currently applicable to us is the removal of the exception related to intraperiod tax allocation. We began applying the general methodology regarding the intraperiod allocation of tax expense in 2021. After the adoption of ASU 2019-12, in periods where we have a loss from continuing operations, the amount of taxes attributable to continuing operations will be determined without regard to the tax effect of other items, including changes in unrealized gains related to marketable securities. The adoption of this standard did not have a material impact on our condensed consolidated financial statements. In August 2020, FASB issued ASU No. 2020-08, Codification Improvement to Subtopic 310-20, Receivables – Nonrefundable Fees and Other Costs . The new guidance states that an entity should reevaluate whether a callable debt security is within scope of Topic 310-20. ASU 2020-08 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. We adopted ASU No. 2020-08 in the first quarter of 2021 and applied the guidance prospectively. The adoption of this new standard did not have a material impact on our condensed consolidated financial statements. Accounting Pronouncement Issued But Not Yet Adopted In March 2020, FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848) . The new guidance contains practical expedients for reference rate reform related activities that impact debt, leases, derivatives, and other contracts. The guidance in ASU 2020-04 is optional and may be elected over time as reference rate reform activities occur. We continue to evaluate the impact of the guidance and may apply the elections as applicable as changes occur.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements Fair value accounting is applied for all financial assets and liabilities that are recognized or disclosed at fair value in the consolidated financial statements on a recurring basis (at least annually). Our financial instruments consist of cash and cash equivalents, marketable securities, accounts receivables, accounts payable, accrued liabilities and long-term debt. Long-term debt is reported at amortized cost on our condensed consolidated balance sheets. Cash and cash equivalents, marketable securities and restricted cash are reported at their respective fair values on our condensed consolidated balance sheets. The remaining financial instruments are reported on our interim condensed consolidated balance sheets at cost that approximate current fair values due to their relatively short maturities. Assets and liabilities recorded at fair value on a recurring basis in the condensed consolidated balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows: Level 1 – Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date; Level 2 – Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities 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 related assets or liabilities; and Level 3 – Unobservable inputs that are significant to the measurement of the fair value of the assets or liabilities that are supported by little or no market data. The following table summarizes our financial assets measured at fair value on a recurring basis (in thousands): September 30, 2021 Total Level 1 Level 2 Level 3 Financial Assets: Money market funds $ 367,951 $ 367,951 $ — $ — Corporate debt securities 7,141 — $ 7,141 — U.S. government agency securities 1,329 — 1,329 — Certificates of deposits 245 — 245 — U.S. government securities 25,182 — 25,182 — Total financial assets $ 401,848 $ 367,951 $ 33,897 $ — December 31, 2020 Total Level 1 Level 2 Level 3 Financial Assets: Money market funds $ 486,174 $ 486,174 $ — $ — Corporate debt securities 29,804 — 29,804 — U.S. government agency securities 15,943 — 15,943 — Certificates of deposits 243 — 243 — U.S. government securities 20,136 — 20,136 — Total financial assets $ 552,300 $ 486,174 $ 66,126 $ — We estimate the fair values of our investments in corporate debt securities, government and government related securities and certificates of deposits by taking into consideration valuations obtained from third-party pricing services. The fair value of our marketable securities classified within Level 2 is based upon observable inputs that may include benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers and reference data including market research publications. At September 30, 2021, and December 31, 2020 , the weighted average remaining contractual maturities of our Level 2 investments was 19 months and all of these investments are rated A-1/P-1 or A/A2, or higher, by Moody’s and Standard & Poor’s.

Available-for-Sale Securities

Available-for-Sale Securities	9 Months Ended
	Sep. 30, 2021
Investments, Debt and Equity Securities [Abstract]
Available-for-Sale Securities	4. Available-for-Sale Securities Estimated fair values of available-for-sale securities are generally based on prices obtained from commercial pricing services. The following table is a summary of available-for-sale securities recorded in cash and cash equivalents, restricted cash, or marketable securities in our interim condensed consolidated balance sheets (in thousands): September 30, 2021 Amortized Unrealized Unrealized Estimated Fair Cost Gains (Losses) Value Financial Assets: Money market funds $ 367,951 $ — $ — $ 367,951 Corporate debt securities 7,141 3 ( 3 ) 7,141 U.S. government agency securities 1,329 — — 1,329 Certificates of deposits 244 1 — 245 U.S. government securities 25,182 2 ( 2 ) 25,182 Total $ 401,847 $ 6 $ ( 5 ) $ 401,848 December 31, 2020 Amortized Unrealized Unrealized Estimated Fair Cost Gains (Losses) Value Financial Assets: Money market funds $ 486,174 $ — $ — $ 486,174 Corporate debt securities 29,641 163 — 29,804 U.S. government agency securities 15,906 37 — 15,943 Certificates of deposits 241 2 — 243 U.S. government securities 20,036 100 — 20,136 Total $ 551,998 $ 302 $ — $ 552,300 The following table summarizes the classification of the available-for-sale securities on our interim condensed consolidated balance sheets (in thousands): September 30, 2021 December 31, 2020 Cash and cash equivalents $ 367,951 $ 486,174 Short-term marketable securities 3,205 66,126 Long-term marketable securities 30,692 — Total $ 401,848 $ 552,300 We do not intend to sell the investments that are in an unrealized loss position, and it is unlikely that we will be required to sell the investments before recovery of their amortized cost basis, which may be maturity. We have determined the gross unrealized losses on our marketable securities were temporary in nature during the periods presented. As of September 30, 2021, we did not have any available-for-sale debt securities in a continuous unrealized position greater than 12 months.

Balance Sheet Components

Balance Sheet Components	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheet Components	5. Balance Sheet Components Inventories Inventories consist of the following (in thousands): September 30, 2021 December 31, 2020 Raw materials $ 10,810 $ 11,273 Work-in-process 38,531 26,994 Finished goods 2,171 1,956 Total inventories $ 51,512 $ 40,223 We have capitalized $ 419,000 and $ 477,000 of stock-based compensation expense to our inventories for the three months ended September 30, 2021 and 2020 , respectively; and $ 1.3 million and $ 1.4 million for the nine months ended September 30, 2021 and 2020 , respectively. We also have capitalized $ 40,000 and $ 70,000 of depreciation expense to our inventories for the three and nine months ended September 30, 2021 and 2020 respectively; and $ 129,000 and $ 220,000 for the nine months ended September 30, 2021 and 2020, respectively. See Note 9—Stock-based Compensation for details on stock-based compensation expenses recognized during the three and nine months ended September 30, 2021 and 2020. Property and Equipment Property and equipment consists of the following (in thousands): September 30, 2021 December 31, 2020 Laboratory equipment $ 13,973 $ 11,922 Computer equipment 3,241 3,023 Leasehold improvements 32,281 32,281 Construction-in-progress 309 517 Total property and equipment 49,804 47,743 Less: accumulated depreciation and amortization ( 14,389 ) ( 9,861 ) Property and equipment, net $ 35,415 $ 37,882 Accrued liabilities Accrued liabilities consist of the following (in thousands): September 30, 2021 December 31, 2020 Accrued research and development costs $ 11,822 $ 10,677 Accrued manufacturing costs 9,480 9,125 Accrued professional and consulting services 6,877 4,107 Accrued sales deductions 8,188 6,405 Other 930 819 Total accrued liabilities $ 37,297 $ 31,133

Long-term Debt

Long-term Debt	9 Months Ended
	Sep. 30, 2021
Disclosure Text Block [Abstract]
Long-term Debt	6. Long-term Debt Term Loan On December 17, 2019, we entered into the Loan Agreement, or Term Loan, with funds managed by Pharmakon Advisors LP, which are BioPharma Credit PLC, as collateral agent, Biopharma Credit Investments V (Master) LP, as a lender, and BPCR Limited Partnership, as a lender, and collectively, the Lenders, for a senior secured credit facility consisting of an initial tranche of $ 75.0 million and the option to draw an additional $ 75.0 million until December 31, 2020. The first tranche, in the amount of $ 75.0 million, was funded in connection with the closing date of the Term Loan in December 2019, and the second tranche in the amount of $ 75.0 million was funded in November 2020. The Term Loan carries a 72 -month term. The Term Loan bears interest at a floating per annum interest rate equal to 7.00 % plus the greater of (a) the 3-month LIBOR rate and (b) 2 %. In the event we default, the interest rate would be 3 % above the rate that is otherwise applicable thereto. Interest on amounts outstanding are payable quarterly in arrears. The Term Loan repayment schedule provides for interest only payments for the first 39 months , followed by consecutive equal quarterly payments of principal and interest commencing in March 2023 and continuing through the maturity in December 2025. We have the option to prepay all or a portion of the borrowed amounts under the Term Loan. If we exercise this option, we must pay a prepayment fee between 1 % and 3 % of the principal amount being prepaid depending on the timing of the prepayment, or Prepayment Fee. If the prepayment occurs before December 2022, we must also pay an amount equal to the sum of all interest that would have accrued and been payable from date of prepayment through December 2022, or Make Whole Amount. We are obligated to pay an additional fee to the Lenders determined by multiplying the principal amount being paid or prepaid multiplied by 2 %, or Paydown Fee, when such payments are made. In the event of default or change in control, all unpaid principal and all accrued and unpaid interest amounts (if any) become immediately due and payable, at which point, we will be subject to the Prepayment Fee, the Make Whole Amount (if any) and the Paydown Fee. Events of default include, but are not limited to, a payment default, a material adverse change, and insolvency. The obligations under the Term Loan are secured by a first priority security interest in and a lien on substantially all of our assets, subject to certain exceptions. Debt issuance costs paid directly to the Lenders of $ 1.1 million and the other debt issuance costs of $ 0.5 million were treated as discounts on the Term Loan. These debt discounts along with the Paydown Fee are being amortized or accreted to interest expenses throughout the life of the Term Loan using the effective interest rate method. In addition, we paid the Lenders $ 1.1 million for the option to draw the additional $ 75.0 million, which was capitalized as a deferred asset and amortized on a straight-line basis through December 31, 2020. Any remaining unamortized amount was reclassed to debt discount at the time of closing of the second tranche of the Term Loan. We closed the second tranche of the Term Loan in November 2020, and $ 0.2 million of the unamortized deferred asset related to the option to draw the second tranche was reclassed as the discount on the notes payable. As of September 30, 2021 , there were unamortized issuance costs and debt discounts of $ 1.4 million, which were recorded as a direct deduction from the Term Loan on the condensed consolidated balance sheet. Future payments of principal and interest on the Term Loan as of September 30, 2021 (in thousands): 2021 (three months) $ 3,375 2022 13,500 2023 62,813 2024 58,313 2025 53,813 Total minimum payments 191,814 Less: amount representing interest ( 38,814 ) Less: amount representing Paydown Fee ( 3,000 ) Long-term debt, gross 150,000 Discount on notes payable ( 1,440 ) Accretion of Paydown Fee 948 Long-term debt $ 149,508

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. Commitments and Contingencies Leases We have operating leases for our headquarters in South San Francisco, where we have office and research and development laboratory facilities, and equipment. Our leases have remaining lease terms of 1 to 10 years. Most of these leases require monthly lease payments that may be subject to annual increases throughout the lease term. Certain of these leases include renewal options at our election, with renewal terms that can extend the lease term from 1 to 10 years. These optional periods have not been considered in the determination of the right-of-use assets, or ROU assets, or lease liabilities associated with these leases as we did not consider it reasonably certain that we would exercise the options. Lease costs included in operating expense in the interim condensed consolidated statement of operations and comprehensive loss in relation to these operating leases were $ 2.4 million and $ 3.1 million for the three months ended September 30, 2021 and 2020 , respectively; and $ 8.0 million and $ 9.3 million for the nine months ended September 30, 2021 and 2020 , respectively. Included in these lease costs were variable lease costs, which were not included within the measurement of our operating ROU assets and operating lease liabilities in the amount of $ 0.6 million and $ 0.7 million for the three months ended September 30, 2021 and 2020 , respectively; and $ 2.6 million and $ 2.0 million for the nine months ended September 30, 2021 and 2020, respectively. The variable lease cost is comprised primarily of our cost in certain research and development arrangements that contain embedded equipment, and our proportionate share of operating expenses, property taxes, and insurance in relation with our facility lease. These costs are classified as operating lease expense due to our election to not separate lease and non-lease components. Supplemental information related to leases for the period reported is as follows (in thousands, except weighted-average remaining lease term and weighted-average discount rate): Nine Months Ended September 30, 2021 2020 ROU assets obtained in exchange for new operating lease $ — $ 205 Cash paid for amounts included in the measurement of lease 8,862 4,811 Weighted-average remaining lease term of operating leases 8.5 9.5 Weighted-average discount rate of operating leases 8.7 % 8.7 % The majority of our lease costs are driven by our operating lease for our headquarters, where we have office and research and development laboratory facilities. In March 2017, we entered into a noncancelable operating lease, or Original Lease, for approximately 67,185 square feet of space in South San Francisco, California, or Prior Premises. The Original Lease term commenced in November 2017 as we gained control over physical access to the Prior Premises for a 10-year period. In August 2018, we entered into an amendment to the Original Lease, or Lease Amendment, to relocate the leased premises from the Prior Premises to a to-be-constructed building consisting of approximately 164,150 rentable square feet of space, or Substitute Premises, when the Substitute Premises were ready for occupancy, or Substitute Premises Payment Commencement Date. The Lease Amendment has a contractual term, or Substitute Premises Term, of 10 years from the Substitute Premises Payment Commencement Date. The Lease Amendment grants us an option to extend the Lease Amendment for an additional 10 -year period. Future minimum rental payments under the Lease Amendment during the 10 -year term are $ 121.5 million in the aggregate. Under the Lease Amendment, we are obligated to pay to the landlord certain costs, including taxes and operating expenses. The Lease Amendment also provides a tenant inducement allowance of up to $ 27.9 million, of which $ 4.1 million, if utilized, would be repaid to the landlord in the form of additional monthly rent with interest applied. As of September 30, 2021 , we have capitalized $ 32.3 million of costs within property and equipment, net for construction of leasehold improvements at the Substitute Premises, which were mostly acquired with the tenant inducement provided under the Lease Amendment. After relocating to the Substitute Premises, we surrendered and delivered the Prior Premises to the landlord in May 2020, upon which time we had no further obligations with respect to the Prior Premises other than with respect to the Initial Allowance, which we will repay to the landlord in the form of additional monthly rent with interest applied over the term of the Original Lease through November 2027. Upon signing of the Lease Amendment, we re-evaluated the remaining useful life of the leasehold improvements at the Prior Premises and started to amortize the leasehold improvements over the remaining period of expected use, resulting in an acceleration of depreciation expenses of approximately $ 3.8 million for the nine months ended September 30, 2020 . No acceleration of depreciation expense was recorded for either the three months ended September 30, 2020 or the three or nine months ended September 30, 2021. As of September 30, 2021, the maturities of our operating lease liabilities were as follows (in thousands): Year ending December 31, Amount 2021 (three months) $ 2,979 2022 12,222 2023 12,584 2024 12,948 2025 13,368 Thereafter 60,507 Total lease payments 114,608 Less: Imputed interest ( 34,164 ) Present value of operating lease liabilities $ 80,444 The operating leases require us to share in prorated operating expenses and property taxes based upon actual amounts incurred; those amounts are not fixed for future periods and, therefore, are not included in the future commitments listed above. Contingencies In the ordinary course of business, we may be subject to legal claims and regulatory actions that could have a material adverse effect on our business or financial position. We assess our potential liability in such situations by analyzing potential outcomes, assuming various litigation, regulatory and settlement strategies. If we determine a loss is probable and its amount can be reasonably estimated, we accrue an amount equal to the estimated loss. No losses and no provision for a loss contingency have been recorded to date.

Stockholder's Equity

Stockholder's Equity	9 Months Ended
	Sep. 30, 2021
Stockholders' Equity Note [Abstract]
Stockholder's Equity	8. Stockholder's Equity In November 2020, we entered into an at-the-market offering program, or “ATM”, which provides for the offering, issuance and sale by us of shares of our common stock from time to time for aggregate gross proceeds of up to $ 200.0 million. As of September 30, 2021, we have sold and issued 1,601,884 shares of common stock pursuant to the ATM, with total gross proceeds of $ 45.4 million before deducting underwriting discounts, commissions, and other offering expenses payable by us of $ 1.4 million.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2021
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	9. Stock-Based Compensation We have three stock-based compensation plans – the Amended and Restated 2017 Inducement Equity Plan, or 2017 Inducement Plan, the Amended and Restated 2015 Stock Option and Incentive Plan, or 2015 Plan, and the 2012 Stock Option and Grant Plan, or 2012 Plan. As of September 30, 2021 , there were 1,786,479 shares reserved under the 2017 Inducement Plan and 5,100,077 shares reserved under the 2015 Plan for the future issuance of equity awards. Upon adoption of the 2015 Plan in July 2015, no new awards or grants are permitted under the 2012 Plan. See Note 10 to the Consolidated Financial Statements included in our Annual Report on Form 10-K for the year ended December 31, 2020, for additional information related to these stock-based compensation plans. Stock Options The following summarizes option activity under the 2017 Inducement Plan, 2015 Plan and 2012 Plan: Weighted- Number of Average Options Exercise Price Outstanding — December 31, 2020 3,327,330 $ 42.07 Options granted 717,680 42.53 Options exercised ( 97,891 ) 19.84 Options canceled ( 270,192 ) 52.41 Outstanding — September 30, 2021 3,676,927 $ 42.00 The fair values of stock options granted to employees were calculated using the following assumptions: Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Expected term (in years) 6.1 6.1 5.3 - 6.1 5.1 - 6.1 Volatility 71.9 %- 72.0 % 70.7 %- 71.0 % 68.1 % - 72.7 % 69.6 %- 71.8 % Risk-free interest rate 0.9 %- 1.1 % 0.3 %- 0.4 % 0.9 %- 1.1 % 0.3 %- 1.8 % Dividend yield — — — — Restricted Stock Units The following table summarizes activity of restricted stock units, or RSUs, granted to employees with service-based vesting under the 2017 Inducement Plan and 2015 Plan and related information: Weighted- Average Number Grant Date of RSUs Fair Value Non-vested units — December 31, 2020 2,210,356 $ 57.80 RSUs granted 1,631,047 42.71 RSUs vested ( 737,473 ) 54.63 RSUs forfeited ( 463,723 ) 53.46 Non-vested units — September 30, 2021 2,640,207 $ 50.12 Market-Condition Awards Granted to Employees Market-Condition RSU Awards Beginning in June 2020, the Compensation Committee of our Board of Directors has granted awards of RSUs to certain of our senior management, including our executive officers, under the 2015 Plan, the vesting of which is contingent upon the achievement of three escalating stock price targets, which we refer to as the Market-Condition RSU Awards. Since June 1, 2020, certain awards have been forfeited in connection with employee terminations and new awards have been granted in connection with new appointments, respectively, with awards for up to an aggregate of 457,100 RSUs outstanding as of September 30, 2021 . Upon the achievement of the respective stock price targets, 50% of the RSUs allotted to that tranche will vest, while the remaining 50% will vest on the first anniversary of the date the stock price target was achieved, subject to the employee’s continued employment or other service relationship with us through such vesting date. Under the terms of the awards, if the stock price targets are not achieved for all or some of the tranches on or before June 30, 2024, the unvested awards will be automatically terminated and forfeited. The compensation cost for the RSUs with a market condition is not reversed when the market condition is not satisfied. The target prices and vesting tranches are set forth in the table below: Stock Price Targets Number of Units Allowed $ 109.20 91,420 $ 145.60 159,985 $ 182.00 205,695 The grant date fair value of the Market-Condition RSU Awards was estimated using a Monte Carlo simulation model, which includes variables such as the expected volatility of our share price and interest rates to generate potential future outcomes. We recognize the related compensation expense on a straight-line basis over the applicable derived service periods, which are the estimated periods of time that would be required to satisfy the market conditions. The following table summarizes the Market-Condition RSU Awards granted and forfeited during the nine months ended September 30, 2021: Weighted- Weighted- Average Average Remaining Aggregate Number Grant Date Vesting Intrinsic of RSUs Fair Value Period (years) Value Non-vested market-condition awards — December 31, 2020 414,700 $ 49.95 1.21 Granted 84,800 13.88 1.82 Forfeited ( 42,400 ) 49.95 0.46 Non-vested market condition awards — September 30, 2021 457,100 $ 43.26 0.55 $ 11,647 The following table summarizes the assumptions used to estimate the fair value of the Market-Condition RSU Awards as of the grant date: Valuation date stock price $ 37.20 Expected term 3.1 years Volatility 66.6 % Risk-free interest rate 0.3 % Dividend yield — At September 30, 2021 , total unrecognized compensation expense related to non-vested Market-Condition RSU Awards was $ 5.5 million, which is expected to be recognized over their respective remaining derived service periods. The weighted average remaining derived service period is 0.55 years. For the three and nine months ended September 30, 2021 , we recognized $ 2.2 million and $ 6.8 million, respectively, in stock-based compensation expense related to the Market-Condition RSU Awards. Stock-Based Compensation Expense Total stock-based compensation recognized by function included in the condensed consolidated statements of operations and comprehensive loss was as follows (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Research and development $ 4,562 $ 4,234 $ 15,616 $ 13,014 Selling, general and administrative 13,514 14,928 43,648 39,086 Total stock-based compensation expense $ 18,076 $ 19,162 $ 59,264 $ 52,100

Net Loss per Share

Net Loss per Share	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Net Loss per Share	10. Net Loss per Share Basic net loss per share is computed by dividing net loss by the weighted-average number of common shares outstanding for the period. Since we were in a loss position for all periods presented, diluted net loss per share is the same as basic net loss per share for all periods as the inclusion of all potential common shares outstanding would have been anti-dilutive. The following securities were not included in the diluted net loss per share calculations because their effect was anti-dilutive: Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Options to purchase common stock 3,676,927 3,416,050 3,676,927 3,416,050 Restricted stock units 3,097,307 2,597,497 3,097,307 2,597,497 Total 6,774,234 6,013,547 6,774,234 6,013,547

Subsequent event

Subsequent event	9 Months Ended
	Sep. 30, 2021
Subsequent Events [Abstract]
Subsequent Event	11. Subsequent Event On October 26, 2021, we donated $ 0.5 million to the GBT Foundation, a California nonprofit public benefit corporation we established earlier in 2021. The GBT Foundation is a related party affiliate as certain officers of the Company also serve, without additional compensation, as directors or officers of the GBT Foundation. The purpose of the GBT Foundation is to fund programs that will support people within the sickle cell disease community and beyond through education, empowerment, improved healthcare access and enhanced health equity.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of the accompanying unaudited interim condensed consolidated financial statements in accordance with U.S. GAAP requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of variable consideration and costs and expenses during the reporting period. We base our estimates and assumptions on historical experience when available and on various factors that we believe to be reasonable under the circumstances. We evaluate our estimates and assumptions on an ongoing basis. Our actual results could differ from these estimates under different assumptions or conditions.
Concentration of Risk	Concentration of Risk Credit Risk We invest in a variety of financial instruments and, by our Board approved investment policy, limit the amount of credit exposure with any one issuer, industry or geographic area for investments other than instruments backed by the U.S. federal government. Major Customers We have entered into distribution agreements with certain limited specialty pharmacies and specialty distributors. For the nine months ended September 30, 2021 , our two largest customers represented approximately 84 % of our product revenue and approximately 76 % of our accounts receivable balance at September 30, 2021. Major Suppliers We do not currently have any of our own manufacturing facilities, and, therefore, depend on an outsourced manufacturing strategy for the production of Oxbryta for commercial use and for the production of our product candidates for clinical trials. We have contracts in place with third-party manufacturers that are approved for the commercial production of Oxbryta and third-party suppliers that are approved for Oxbryta’s active pharmaceutical ingredient. Although there are potential sources of supply other than our existing manufacturers and suppliers, any new supplier would be required to qualify under applicable regulatory requirements.
Principles of Consolidation	Principles of Consolidation The accompanying unaudited interim condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany transactions and balances have been eliminated upon consolidation.
Significant Accounting Policies	Significant Accounting Policies Except as noted below, there have been no material revisions in our significant accounting policies described in Note 2 to the consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2020 .
Accounting Pronouncements Adopted	Accounting Pronouncements Adopted In December 2019, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, No. 2019-12, Income Taxes (Topic 740), Simplifying the Accounting for Income Taxes . The guidance eliminates 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. It also clarifies and simplifies other aspects of the accounting for income taxes. ASU 2019-12 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020, and the applicable amendments will be applied on a prospective basis. We adopted ASU No. 2019-12 in the first quarter of 2021 and applied the guidance prospectively. The only aspect of ASU 2019-12 that is currently applicable to us is the removal of the exception related to intraperiod tax allocation. We began applying the general methodology regarding the intraperiod allocation of tax expense in 2021. After the adoption of ASU 2019-12, in periods where we have a loss from continuing operations, the amount of taxes attributable to continuing operations will be determined without regard to the tax effect of other items, including changes in unrealized gains related to marketable securities. The adoption of this standard did not have a material impact on our condensed consolidated financial statements. In August 2020, FASB issued ASU No. 2020-08, Codification Improvement to Subtopic 310-20, Receivables – Nonrefundable Fees and Other Costs . The new guidance states that an entity should reevaluate whether a callable debt security is within scope of Topic 310-20. ASU 2020-08 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. We adopted ASU No. 2020-08 in the first quarter of 2021 and applied the guidance prospectively. The adoption of this new standard did not have a material impact on our condensed consolidated financial statements.
Accounting Pronouncement Issued But Not Yet Adopted	Accounting Pronouncement Issued But Not Yet Adopted In March 2020, FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848) . The new guidance contains practical expedients for reference rate reform related activities that impact debt, leases, derivatives, and other contracts. The guidance in ASU 2020-04 is optional and may be elected over time as reference rate reform activities occur. We continue to evaluate the impact of the guidance and may apply the elections as applicable as changes occur.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value, Assets Measured on Recurring Basis	The following table summarizes our financial assets measured at fair value on a recurring basis (in thousands): September 30, 2021 Total Level 1 Level 2 Level 3 Financial Assets: Money market funds $ 367,951 $ 367,951 $ — $ — Corporate debt securities 7,141 — $ 7,141 — U.S. government agency securities 1,329 — 1,329 — Certificates of deposits 245 — 245 — U.S. government securities 25,182 — 25,182 — Total financial assets $ 401,848 $ 367,951 $ 33,897 $ — December 31, 2020 Total Level 1 Level 2 Level 3 Financial Assets: Money market funds $ 486,174 $ 486,174 $ — $ — Corporate debt securities 29,804 — 29,804 — U.S. government agency securities 15,943 — 15,943 — Certificates of deposits 243 — 243 — U.S. government securities 20,136 — 20,136 — Total financial assets $ 552,300 $ 486,174 $ 66,126 $ —

Available-for-Sale Securities (

Available-for-Sale Securities (Tables)	9 Months Ended
	Sep. 30, 2021
Investments, Debt and Equity Securities [Abstract]
Summary of Available-for-Sale Securities	The following table is a summary of available-for-sale securities recorded in cash and cash equivalents, restricted cash, or marketable securities in our interim condensed consolidated balance sheets (in thousands): September 30, 2021 Amortized Unrealized Unrealized Estimated Fair Cost Gains (Losses) Value Financial Assets: Money market funds $ 367,951 $ — $ — $ 367,951 Corporate debt securities 7,141 3 ( 3 ) 7,141 U.S. government agency securities 1,329 — — 1,329 Certificates of deposits 244 1 — 245 U.S. government securities 25,182 2 ( 2 ) 25,182 Total $ 401,847 $ 6 $ ( 5 ) $ 401,848 December 31, 2020 Amortized Unrealized Unrealized Estimated Fair Cost Gains (Losses) Value Financial Assets: Money market funds $ 486,174 $ — $ — $ 486,174 Corporate debt securities 29,641 163 — 29,804 U.S. government agency securities 15,906 37 — 15,943 Certificates of deposits 241 2 — 243 U.S. government securities 20,036 100 — 20,136 Total $ 551,998 $ 302 $ — $ 552,300
Summary of Classification of Available-for-Sale Securities on Consolidated Balance Sheets	The following table summarizes the classification of the available-for-sale securities on our interim condensed consolidated balance sheets (in thousands): September 30, 2021 December 31, 2020 Cash and cash equivalents $ 367,951 $ 486,174 Short-term marketable securities 3,205 66,126 Long-term marketable securities 30,692 — Total $ 401,848 $ 552,300

Balance Sheet Components (Table

Balance Sheet Components (Tables)	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Inventories	Inventories consist of the following (in thousands): September 30, 2021 December 31, 2020 Raw materials $ 10,810 $ 11,273 Work-in-process 38,531 26,994 Finished goods 2,171 1,956 Total inventories $ 51,512 $ 40,223
Property and Equipment, Net	Property and equipment consists of the following (in thousands): September 30, 2021 December 31, 2020 Laboratory equipment $ 13,973 $ 11,922 Computer equipment 3,241 3,023 Leasehold improvements 32,281 32,281 Construction-in-progress 309 517 Total property and equipment 49,804 47,743 Less: accumulated depreciation and amortization ( 14,389 ) ( 9,861 ) Property and equipment, net $ 35,415 $ 37,882
Accrued Liabilities	Accrued liabilities consist of the following (in thousands): September 30, 2021 December 31, 2020 Accrued research and development costs $ 11,822 $ 10,677 Accrued manufacturing costs 9,480 9,125 Accrued professional and consulting services 6,877 4,107 Accrued sales deductions 8,188 6,405 Other 930 819 Total accrued liabilities $ 37,297 $ 31,133

Long-term Debt (Tables)

Long-term Debt (Tables)	9 Months Ended
	Sep. 30, 2021
Text Block [Abstract]
Schedule of Future payments of principal and interest on the Term Loan	Future payments of principal and interest on the Term Loan as of September 30, 2021 (in thousands): 2021 (three months) $ 3,375 2022 13,500 2023 62,813 2024 58,313 2025 53,813 Total minimum payments 191,814 Less: amount representing interest ( 38,814 ) Less: amount representing Paydown Fee ( 3,000 ) Long-term debt, gross 150,000 Discount on notes payable ( 1,440 ) Accretion of Paydown Fee 948 Long-term debt $ 149,508

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Summary of supplemental information related to leases	Supplemental information related to leases for the period reported is as follows (in thousands, except weighted-average remaining lease term and weighted-average discount rate): Nine Months Ended September 30, 2021 2020 ROU assets obtained in exchange for new operating lease $ — $ 205 Cash paid for amounts included in the measurement of lease 8,862 4,811 Weighted-average remaining lease term of operating leases 8.5 9.5 Weighted-average discount rate of operating leases 8.7 % 8.7 %
Schedule of Lessee, Operating Lease, Liability, Maturity	As of September 30, 2021, the maturities of our operating lease liabilities were as follows (in thousands): Year ending December 31, Amount 2021 (three months) $ 2,979 2022 12,222 2023 12,584 2024 12,948 2025 13,368 Thereafter 60,507 Total lease payments 114,608 Less: Imputed interest ( 34,164 ) Present value of operating lease liabilities $ 80,444

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2021
Stock Option Activity	The following summarizes option activity under the 2017 Inducement Plan, 2015 Plan and 2012 Plan: Weighted- Number of Average Options Exercise Price Outstanding — December 31, 2020 3,327,330 $ 42.07 Options granted 717,680 42.53 Options exercised ( 97,891 ) 19.84 Options canceled ( 270,192 ) 52.41 Outstanding — September 30, 2021 3,676,927 $ 42.00
Valuation Assumptions for Stock Awards	The fair values of stock options granted to employees were calculated using the following assumptions: Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Expected term (in years) 6.1 6.1 5.3 - 6.1 5.1 - 6.1 Volatility 71.9 %- 72.0 % 70.7 %- 71.0 % 68.1 % - 72.7 % 69.6 %- 71.8 % Risk-free interest rate 0.9 %- 1.1 % 0.3 %- 0.4 % 0.9 %- 1.1 % 0.3 %- 1.8 % Dividend yield — — — —
Non-Vested Restricted Stock Activity	The following table summarizes activity of restricted stock units, or RSUs, granted to employees with service-based vesting under the 2017 Inducement Plan and 2015 Plan and related information: Weighted- Average Number Grant Date of RSUs Fair Value Non-vested units — December 31, 2020 2,210,356 $ 57.80 RSUs granted 1,631,047 42.71 RSUs vested ( 737,473 ) 54.63 RSUs forfeited ( 463,723 ) 53.46 Non-vested units — September 30, 2021 2,640,207 $ 50.12
Summary of Activity of Market-Condition Awards	The compensation cost for the RSUs with a market condition is not reversed when the market condition is not satisfied. The target prices and vesting tranches are set forth in the table below: Stock Price Targets Number of Units Allowed $ 109.20 91,420 $ 145.60 159,985 $ 182.00 205,695
Valuation Assumptions of Market-Condition Awards	The following table summarizes the Market-Condition RSU Awards granted and forfeited during the nine months ended September 30, 2021: Weighted- Weighted- Average Average Remaining Aggregate Number Grant Date Vesting Intrinsic of RSUs Fair Value Period (years) Value Non-vested market-condition awards — December 31, 2020 414,700 $ 49.95 1.21 Granted 84,800 13.88 1.82 Forfeited ( 42,400 ) 49.95 0.46 Non-vested market condition awards — September 30, 2021 457,100 $ 43.26 0.55 $ 11,647
Summary of Share-based Compensation Arrangements by Share-based Payment Award	The following table summarizes the assumptions used to estimate the fair value of the Market-Condition RSU Awards as of the grant date: Valuation date stock price $ 37.20 Expected term 3.1 years Volatility 66.6 % Risk-free interest rate 0.3 % Dividend yield —
Stock-based Compensation Expense Recognized	Total stock-based compensation recognized by function included in the condensed consolidated statements of operations and comprehensive loss was as follows (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Research and development $ 4,562 $ 4,234 $ 15,616 $ 13,014 Selling, general and administrative 13,514 14,928 43,648 39,086 Total stock-based compensation expense $ 18,076 $ 19,162 $ 59,264 $ 52,100

Net Loss per Share (Tables)

Net Loss per Share (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Potentially Dilutive Securities that were Not Included in Diluted Net Loss per Share Calculations	The following securities were not included in the diluted net loss per share calculations because their effect was anti-dilutive: Three Months Ended Nine Months Ended September 30, September 30, 2021 2020 2021 2020 Options to purchase common stock 3,676,927 3,416,050 3,676,927 3,416,050 Restricted stock units 3,097,307 2,597,497 3,097,307 2,597,497 Total 6,774,234 6,013,547 6,774,234 6,013,547

Organization and Basis of Prese

Organization and Basis of Presentation - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Class of Stock [Line Items]
Cumulative net losses	$ (1,201,979)	$ (986,469)

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Detail) - Customer Concentration Risk [Member] - Two Major Customers [Member]	9 Months Ended
	Sep. 30, 2021
Revenue, Product and Service Benchmark [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage	84.00%
Accounts Receivable [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage	76.00%

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value Assets Measured on Recurring Basis (Detail) - Fair Value Measurements, Recurring [Member] - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	$ 401,848	$ 552,300
U.S. Government Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	25,182	20,136
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	367,951	486,174
Level 1 [Member] | U.S. Government Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	0
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	33,897	66,126
Level 2 [Member] | U.S. Government Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	25,182	20,136
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	0
Level 3 [Member] | U.S. Government Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	0
Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	367,951	486,174
Money Market Funds [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	367,951	486,174
Money Market Funds [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	0
Money Market Funds [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	0
Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	7,141	29,804
Corporate Debt Securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	0
Corporate Debt Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	7,141	29,804
Corporate Debt Securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	0
U.S. Government Agency Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	1,329	15,943
U.S. Government Agency Securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	0
U.S. Government Agency Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	1,329	15,943
U.S. Government Agency Securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	0
Certificates of Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	245	243
Certificates of Deposits [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	0
Certificates of Deposits [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	245	$ 243
Certificates of Deposits [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets, fair value	$ 0

Available-for-Sale Securities -

Available-for-Sale Securities - Summary of Available-for-Sale Securities (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Available for sale securities, Amortized Cost	$ 401,847	$ 551,998
Available for sale securities, Unrealized Gains	6	302
Available for sale securities, Unrealized (Losses)	5
Available for sale securities, Estimated Fair Value	401,848	552,300
Corporate Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available for sale securities, Amortized Cost	7,141	29,641
Available for sale securities, Unrealized Gains	3	163
Available for sale securities, Unrealized (Losses)	3
Available for sale securities, Estimated Fair Value	7,141	29,804
U.S. Government Agency Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available for sale securities, Amortized Cost	1,329	15,906
Available for sale securities, Unrealized Gains		37
Available for sale securities, Estimated Fair Value	1,329	15,943
Money Market Funds [Member]
Debt Securities, Available-for-sale [Line Items]
Available for sale securities, Amortized Cost	367,951	486,174
Available for sale securities, Estimated Fair Value	367,951	486,174
Certificates of Deposits [Member]
Debt Securities, Available-for-sale [Line Items]
Available for sale securities, Amortized Cost	244	241
Available for sale securities, Unrealized Gains	1	2
Available for sale securities, Estimated Fair Value	245	243
U.S. Government Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available for sale securities, Amortized Cost	25,182	20,036
Available for sale securities, Unrealized Gains	2	100
Available for sale securities, Unrealized (Losses)	2
Available for sale securities, Estimated Fair Value	$ 25,182	$ 20,136

Available-for-Sale Securities_2

Available-for-Sale Securities - Summary of Classification of Available-for-Sale Securities on Consolidated Balance Sheets (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Cash and cash equivalents	$ 367,951	$ 486,174
Short-term marketable securities	3,205	66,126
Long-term marketable securities	30,692
Total	$ 401,848	$ 552,300

Balance Sheet Components - Inve

Balance Sheet Components - Inventories (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Balance Sheet Components [Abstract]
Raw materials	$ 10,810	$ 11,273
Work-in-process	38,531	26,994
Finished goods	2,171	1,956
Total inventories	$ 51,512	$ 40,223

Balance Sheet Components - Prop

Balance Sheet Components - Property and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 49,804	$ 47,743
Less: accumulated depreciation and amortization	(14,389)	(9,861)
Property and equipment, net	35,415	37,882
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	13,973	11,922
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	3,241	3,023
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	32,281	32,281
Construction-in-Progress [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 309	$ 517

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Balance Sheet Components [Abstract]
Share based compensation expense capitalized	$ 419,000	$ 477,000	$ 1,300	$ 1,400
Capitalized depreciation expenses	$ 40,000	$ 70,000	$ 129,000	$ 220,000

Balance Sheet Components - Accr

Balance Sheet Components - Accrued Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Balance Sheet Components [Abstract]
Accrued research and development costs	$ 11,822	$ 10,677
Accrued manufacturing costs	9,480	9,125
Accrued professional and consulting services	6,877	4,107
Accrued sales deductions	8,188	6,405
Other	930	819
Total accrued liabilities	$ 37,297	$ 31,133

Long-term Debt - Additional Inf

Long-term Debt - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Nov. 30, 2020	Dec. 31, 2019
Long term debt	$ 149,508		$ 148,815
Debt issuance costs paid	$ 49	$ 130
Term Loan
Debt additional borrowing capacity				$ 75,000
Debt Instrument, Term	72 months
Debt Instrument, Basis Spread on Variable Rate	7.00%
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	2.00%
Debt Instrument Additional Interest Rate On Debt Default	3.00%
Debt Instrument Periodic Payment Of Interest	Interest on amounts outstanding are payable quarterly in arrears.
Debt Instrument Periodic Payment Of Interest Term	39 months
Debt additional paydown fee	2.00%
Debt issuance costs paid	$ 1,100
Other debt issuance cost paid	500
Unamortized issuance costs and debt discounts	1,400
Debt additional paydown fee	$ 1,100
Unamortized dedt discount				200
Term Loan | Maximum
Debt prepayment fee	3.00%
Term Loan | Minimum
Debt prepayment fee	1.00%
Secured Debt
Debt maximum borrowing capacity	$ 75,000
Debt additional borrowing capacity			$ 75,000
Long term debt				$ 75,000	$ 75,000

Long-term Debt-Schedule of Futu

Long-term Debt-Schedule of Future payments of principal and interest on the Term Loan (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Contractual Obligation, Fiscal Year Maturity Schedule [Abstract]
2021 (three months)	$ 3,375
2022	13,500
2023	62,813
2024	58,313
2025	53,813
Total minimum payments	191,814
Less amount representing interest	(38,814)
Less amount representing Paydown Fee	(3,000)
Long-term debt, gross	150,000
Discount on notes payable	(1,440)
Accretion of Paydown Fee	948
Long-term debt	$ 149,508	$ 148,815

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	1 Months Ended		3 Months Ended		9 Months Ended
	Aug. 31, 2018USD ($)ft²	Mar. 31, 2017ft²	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)
Commitment And Contingencies [Line Items]
Facility size | ft²	164,150	67,185
Initial term		10 years
Future minimum rental payments under the Lease term	$ 121,500,000
Operating lease term	10 years
Operating lease term, optional extension	10 years
Repayment of tenant inducement allowance	$ 4,100,000
Contingency losses					$ 0
Provisions for loss contingency					0
Operating Lease Cost			$ 2,400,000	$ 3,100,000	8,000,000	$ 9,300,000
variable lease cost			$ 600,000	$ 700,000	$ 2,600,000	2,000,000
Acceleration of depreciation expenses						0
Maximum [Member]
Commitment And Contingencies [Line Items]
Operating lease remaining lease term					10 years
Minimum [Member]
Commitment And Contingencies [Line Items]
Operating lease remaining lease term					1 year
Leasehold Improvements [Member]
Commitment And Contingencies [Line Items]
Property palnt and equipment additions					$ 32,300,000
Depreciation expense						$ 3,800,000
Lease Agreements [Member] | Maximum [Member]
Commitment And Contingencies [Line Items]
Tenant inducement	$ 27,900,000

Commitments and Contingencies_2

Commitments and Contingencies - Supplemental cash flow information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Commitment And Contingencies [Line Items]
ROU assets obtained in exchange for new operating lease		$ 205,000
Accounting Standards Update 2016-02 [Member]
Commitment And Contingencies [Line Items]
ROU assets obtained in exchange for new operating lease	$ 0	205
Cash paid for amounts included in the measurement of lease liabilities	$ 8,862	$ 4,811
Weighted-average remaining lease term of operating leases (in years)	8 years 6 months	9 years 6 months
Weighted-average discount rate of operating leases	8.70%	8.70%

Commitments and Contingencies_3

Commitments and Contingencies - Lessee Operating Lease Liability Maturity (Detail)	Sep. 30, 2021USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2021 (three months)	$ 2,979
2022	12,222
2023	12,584
2024	12,948
2025	13,368
Thereafter	60,507
Total lease payments	114,608
Less: Imputed interest	(34,164)
Present value of operating lease liabilities	$ 80,444

Stockholder's Equity (Additiona

Stockholder's Equity (Additional Information) (Details) - USD ($) $ in Thousands	1 Months Ended	9 Months Ended
	Nov. 30, 2020	Sep. 30, 2021	Dec. 31, 2020
Stock Issued During Period, Shares, New Issues		1,601,884
Commitments and contingencies
Proceeds from issuance of common stock before offering expenses		45,400
Proceeds from Issuance of Common Stock		44,073
Underwriting discounts, commissions, and other offering expenses payable		$ 1,400
Maximum [Member]
Proceeds from Issuance of Common Stock	$ 200,000

Stock-Based Compensation - Plan

Stock-Based Compensation - Plan Summary - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation		$ 59,264	$ 52,100
Market Condition Awards Granted to Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 5,500	$ 5,500
Weighted average derived service period		6 months 18 days
Stock-based compensation	$ 2,200	$ 6,800
2017 Inducement Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance	1,786,479	1,786,479
2015 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance	5,100,077	5,100,077
2015 Plan [Member] | Market Condition Awards Granted to Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares Non-vested period	457,100	457,100		414,700

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Option Activity (Detail)	9 Months Ended
	Sep. 30, 2021$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning balance, outstanding, Number of Options | shares	3,327,330
Options granted, Number of Options | shares	717,680
Options exercised, Number of Options | shares	(97,891)
Options canceled, Number of Options | shares	(270,192)
Ending balance, outstanding, Number of Options | shares	3,676,927
Weighted- Average Exercise Price
Beginning balance, Outstanding, Weighted-Average Exercise Price | $ / shares	$ 42.07
Options granted, Weighted-Average Exercise Price | $ / shares	42.53
Options exercised, Weighted-Average Exercise Price | $ / shares	19.84
Options canceled, Weighted-Average Exercise Price | $ / shares	52.41
Ending balance, Outstanding, Weighted-Average Exercise Price | $ / shares	$ 42

Stock-Based Compensation - Valu

Stock-Based Compensation - Valuation Assumptions for Stock Options Granted (Detail) - Stock Options [Member]	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 years 1 month 6 days	6 years 1 month 6 days
Volatility, minimum	71.90%	70.70%	68.10%	69.60%
Volatility, maximum	72.00%	71.00%	72.70%	71.80%
Risk-free interest rate, minimum	0.90%	0.30%	0.90%	0.30%
Risk-free interest rate, maximum	1.10%	0.40%	1.10%	1.80%
Dividend yield	0.00%	0.00%	0.00%	0.00%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)			5 years 3 months 18 days	5 years 1 month 6 days
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)			6 years 1 month 6 days	6 years 1 month 6 days

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of RSU Activity Granted to Employees with Service-Based Vesting (Detail) - 2017 Inducement Plan and 2015 Plan [Member]	9 Months Ended
	Sep. 30, 2021$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance - Non-vested units, Weighted-Average Grant Date Fair Value | $ / shares	$ 57.80
RSUs granted, Weighted-Average Grant Date Fair Value | $ / shares	42.71
RSUs vested, Weighted-Average Grant Date Fair Value | $ / shares	54.63
RSUs forfeited, Weighted-Average Grant Date Fair Value | $ / shares	53.46
Ending Balance - Non-vested units, Weighted-Average Grant Date Fair Value | $ / shares	$ 50.12
RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance - Non-vested market-condition awards | shares	2,210,356
RSUs granted, Number of RSUs | shares	1,631,047
RSUs vested, Number of RSUs | shares	(737,473)
RSUs forfeited, Number of RSUs | shares	(463,723)
Ending Balance - Non-vested market-condition awards | shares	2,640,207

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Share-based Compensation Arrangements by Share-based Payment Award (Detail) - Market-Condition RSU Awards [Member]	Sep. 30, 2021$ / sharesshares
Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Price Targets | $ / shares	$ 109.20
Number of Units Allowed | shares	91,420
Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Price Targets | $ / shares	$ 145.60
Number of Units Allowed | shares	159,985
Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Price Targets | $ / shares	$ 182
Number of Units Allowed | shares	205,695

Stock-Based Compensation - Su_3

Stock-Based Compensation - Summary of Activity of Market-Condition Awards (Detail) - Market Condition Awards Granted to Employees [Member] - 2015 Plan [Member] - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance - Non-vested market-condition awards	414,700
Number of Units granted	84,800
Number of Units forfeited	(42,400)
Ending Balance - Non-vested market-condition awards	457,100	414,700
Beginning Balance - Non-vested units, Weighted-Average Grant Date Fair Value	$ 49.95
Weighted-Average Grant Date Fair Value granted	13.88
Weighted-Average Grant Date Fair Value forfeited	49.95
Ending Balance - Non-vested units, Weighted-Average Grant Date Fair Value	$ 43.26	$ 49.95
Non-vested units, Weighted-Average remaining vesting period(years)	6 months 18 days	1 year 2 months 15 days
Non-vested units, Weighted-Average remaining vesting period (years) granted	1 year 9 months 25 days
Non-vested units, Weighted-Average remaining vesting period (years) forfeited	5 months 15 days
Non-vested units, Aggregate Intrinsic Value	$ 11,647

Stock-Based Compensation - Va_2

Stock-Based Compensation - Valuation Assumptions of Market-Condition Awards (Detail) - Market Condition Awards Granted To Employees [Member]	9 Months Ended
	Sep. 30, 2021$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Valuation date stock price	$ 37.20
Expected term	3 years 1 month 6 days
Volatility	66.60%
Risk-free interest rate	0.30%
Dividend yield	0.00%

Stock-Based Compensation - St_2

Stock-Based Compensation - Stock-Based Compensation Expense Recognized (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 18,076	$ 19,162	$ 59,264	$ 52,100
Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	4,562	4,234	15,616	13,014
Selling, general and administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 13,514	$ 14,928	$ 43,648	$ 39,086

Net Loss per Share - Potentiall

Net Loss per Share - Potentially Dilutive Securities that were Not Included in Diluted Net Loss per Share Calculations (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share	6,774,234	6,013,547	6,774,234	6,013,547
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share	3,676,927	3,416,050	3,676,927	3,416,050
RSU [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share	3,097,307	2,597,497	3,097,307	2,597,497

Subsequent event (Additional in

Subsequent event (Additional information) (Detail) $ in Millions	Oct. 26, 2021USD ($)
Subsequent Event [Member]
Subsequent Event [Line Items]
Donation given	$ 0.5