Sierra Oncology (SRRA) 10-Q 5 Nov 20 2020 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2020	Nov. 02, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Entity Registrant Name	Sierra Oncology, Inc.
Entity Central Index Key	0001290149
Trading Symbol	SRRA
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Small Business	true
Entity Common Stock, Shares Outstanding		11,040,600
Entity Interactive Data Current	Yes
Security Exchange Name	NASDAQ
Title of 12(b) Security	Common Stock, $0.001 par value
Entity File Number	001-37490
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-0138994
Entity Address, Address Line One	c/o 2150 – 885 West Georgia Street
Entity Address, City or Town	Vancouver
Entity Address, State or Province	BC
Entity Address, Country	CA
Entity Address, Postal Zip Code	V6C 3E8
City Area Code	604
Local Phone Number	558-6536
Document Quarterly Report	true
Document Transition Report	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
CURRENT ASSETS:
Cash and cash equivalents	$ 109,014	$ 147,528
Prepaid expenses and other current assets	2,956	2,369
Total current assets	111,970	149,897
Property and equipment, net	63	113
Operating lease right-of-use asset	354	589
Other assets	657	729
TOTAL ASSETS	113,044	151,328
CURRENT LIABILITIES:
Accrued and other liabilities	5,727	7,170
Accounts payable	1,540	1,019
Deferred revenue	200
Warrant liabilities		45,935
Securities issuance obligation		10,485
Total current liabilities	7,467	64,609
Operating lease liability	217	374
TOTAL LIABILITIES	7,684	64,983
Commitments and Contingencies (Note 8)
STOCKHOLDERS’ EQUITY:
Preferred stock, $0.001 par value; 10,000,000 shares authorized as of September 30, 2020 and December 31, 2019; nil shares issued and outstanding as of September 30, 2020 and 103,000 shares of Series A convertible voting preferred stock issued and outstanding as of December 31, 2019		1
Common stock, $0.001 par value; 500,000,000 shares authorized as of September 30, 2020 and December 31, 2019; 10,495,732 and 1,867,176 shares issued and outstanding as of September 30, 2020 and December 31, 2019	10	74
Additional paid-in capital	933,916	851,957
Accumulated deficit	(828,566)	(765,687)
TOTAL STOCKHOLDERS’ EQUITY	105,360	86,345
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 113,044	$ 151,328

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2020	Dec. 31, 2019
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	10,495,732	1,867,176
Common stock, shares outstanding	10,495,732	1,867,176
Series A Convertible Preferred Stock [Member]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	103,000
Preferred stock, shares outstanding	0	103,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Collaboration revenue	$ 100		$ 100
Operating expenses:
Research and development	10,432	$ 10,113	32,212	$ 31,978
General and administrative	4,112	3,151	14,916	9,995
Total operating expenses	14,544	13,264	47,128	41,973
Loss from operations	(14,444)	(13,264)	(47,028)	(41,973)
Other income (expense), net:
Changes in fair value of warrant liabilities			(16,240)
Other income (expense), net	(22)	288	495	961
Total other income (expense), net	(22)	288	(15,745)	961
Loss before provision for (benefit from) income taxes, net	(14,466)	(12,976)	(62,773)	(41,012)
Provision for (benefit from) income taxes, net	39	(73)	106	(199)
Net loss and comprehensive loss	$ (14,505)	$ (12,903)	$ (62,879)	$ (40,813)
Net loss per common share, basic and diluted	$ (1.39)	$ (6.91)	$ (6.09)	$ (21.88)
Weighted-average shares used in computing net loss per common share, basic and diluted	10,441,384	1,867,176	10,331,650	1,865,503

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Series A Convertible Voting Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]
Stockholders Equity, Ending Balance at Dec. 31, 2018	$ 94,479		$ 74	$ 771,817	$ (677,412)
Stockholders Equity, Ending Balance, Shares at Dec. 31, 2018			1,859,120
Issuance of common stock for exercise of stock options	445			445
Issuance of common stock for exercise of stock options, Shares			8,056
Stock-based compensation	1,699			1,699
Net loss	(13,032)				(13,032)
Stockholders Equity, Ending Balance at Mar. 31, 2019	83,591		$ 74	773,961	(690,444)
Stockholders Equity, Ending Balance, Shares at Mar. 31, 2019			1,867,176
Stockholders Equity, Ending Balance at Dec. 31, 2018	94,479		$ 74	771,817	(677,412)
Stockholders Equity, Ending Balance, Shares at Dec. 31, 2018			1,859,120
Net loss	(40,813)
Stockholders Equity, Ending Balance at Sep. 30, 2019	58,848		$ 74	776,999	(718,225)
Stockholders Equity, Ending Balance, Shares at Sep. 30, 2019			1,867,176
Stockholders Equity, Ending Balance at Mar. 31, 2019	83,591		$ 74	773,961	(690,444)
Stockholders Equity, Ending Balance, Shares at Mar. 31, 2019			1,867,176
Stock-based compensation	1,758			1,758
Net loss	(14,878)				(14,878)
Stockholders Equity, Ending Balance at Jun. 30, 2019	70,471		$ 74	775,719	(705,322)
Stockholders Equity, Ending Balance, Shares at Jun. 30, 2019			1,867,176
Stock-based compensation	1,280			1,280
Net loss	(12,903)				(12,903)
Stockholders Equity, Ending Balance at Sep. 30, 2019	58,848		$ 74	776,999	(718,225)
Stockholders Equity, Ending Balance, Shares at Sep. 30, 2019			1,867,176
Stockholders Equity, Ending Balance at Dec. 31, 2019	86,345	$ 1	$ 74	851,957	(765,687)
Stockholders Equity, Ending Balance, Shares at Dec. 31, 2019		103,000	1,867,176
Conversion of Series A convertible voting preferred stock to common stock		$ (1)	$ 8	(7)
Conversion of Series A convertible voting preferred stock to common stock, Shares		(103,000)	7,803,273
Reclassification of warrant liabilities to equity	62,175			62,175
Issuance of common stock	8,782		$ 1	8,781
Issuance of common stock, Shares			725,283
Issuance of warrant in connection with an amendment to the asset purchase agreement	3,188			3,188
Stock-based compensation	918			918
Reverse stock split adjustment			$ (73)	73
Net loss	(31,912)				(31,912)
Stockholders Equity, Ending Balance at Mar. 31, 2020	129,496		$ 10	927,085	(797,599)
Stockholders Equity, Ending Balance, Shares at Mar. 31, 2020			10,395,732
Stockholders Equity, Ending Balance at Dec. 31, 2019	86,345	$ 1	$ 74	851,957	(765,687)
Stockholders Equity, Ending Balance, Shares at Dec. 31, 2019		103,000	1,867,176
Reclassification of warrant liabilities to equity	62,175
Net loss	(62,879)
Stockholders Equity, Ending Balance at Sep. 30, 2020	105,360		$ 10	933,916	(828,566)
Stockholders Equity, Ending Balance, Shares at Sep. 30, 2020			10,495,732
Stockholders Equity, Ending Balance at Mar. 31, 2020	129,496		$ 10	927,085	(797,599)
Stockholders Equity, Ending Balance, Shares at Mar. 31, 2020			10,395,732
Stock-based compensation	3,617			3,617
Net loss	(16,462)				(16,462)
Stockholders Equity, Ending Balance at Jun. 30, 2020	116,651		$ 10	930,702	(814,061)
Stockholders Equity, Ending Balance, Shares at Jun. 30, 2020			10,395,732
Issuance of common stock	1,140			1,140
Issuance of common stock, Shares			100,000
Stock-based compensation	2,074			2,074
Net loss	(14,505)				(14,505)
Stockholders Equity, Ending Balance at Sep. 30, 2020	$ 105,360		$ 10	$ 933,916	$ (828,566)
Stockholders Equity, Ending Balance, Shares at Sep. 30, 2020			10,495,732

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (62,879)	$ (40,813)
Adjustments to reconcile net loss to net cash used in operating activities:
Changes in fair value of warrant liabilities	16,240
Securities issuance obligation	1,485
Stock-based compensation	6,609	4,737
Depreciation and amortization	191	188
Asset impairment	106
Other	108	(101)
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(586)	(416)
Accrued, other and operating lease liabilities	(1,624)	(2,345)
Accounts payable	531	22
Deferred revenue	200
Net cash used in operating activities	(39,619)	(38,728)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property and equipment	(12)	(33)
Net cash used in investing activities	(12)	(33)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock from At-The-Market equity offering, net of offering costs	1,140
Proceeds from exercise of common stock options		445
Net cash provided by financing activities	1,140	445
Effect of foreign exchange rate changes on cash, cash equivalents and restricted cash	(23)	(36)
NET DECREASE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	(38,514)	(38,352)
CASH, CASH EQUIVALENTS AND RESTRICTED CASH — Beginning of period	147,828	106,346
CASH, CASH EQUIVALENTS AND RESTRICTED CASH — End of period	109,314	67,994
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid for (refund of) income taxes, net	17	(95)
Cash paid for interest		246
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING INFORMATION:
Issuance of common stock and common stock warrant in connection with an amendment to the asset purchase agreement	11,970
Reclassification of warrant liabilities to equity	62,175
Right-of-use asset obtained in exchange for operating lease obligation		$ 771
Unpaid deferred financing costs in accrued and other liabilities	$ 94

The Company and Basis of Presen

The Company and Basis of Presentation	9 Months Ended
	Sep. 30, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
The Company and Basis of Presentation	1. Organization and Description of Business Sierra Oncology, Inc. (together with its subsidiaries, collectively referred to as the “Company”), a Delaware corporation, is a late stage biopharmaceutical company focused on the Phase 3 execution, registration and potential commercialization of momelotinib, a novel drug that may address serious unmet needs in myelofibrosis. Momelotinib is a selective and orally-bioavailable JAK1 (Janus kinase 1), JAK2 (Janus kinase 2) and ACVR1 (Activin A receptor type 1) inhibitor with a differentiated mechanism of action that enables it to potentially address all three key drivers of myelofibrosis: anemia of inflammation, constitutional symptoms and enlarged spleen. More than 1,200 subjects have received momelotinib since clinical studies began in 2009, including more than 800 patients treated for myelofibrosis. Several of these patients remain on treatment for more than 10 years. The Company’s portfolio also includes SRA737, a selective, orally bioavailable small molecule inhibitor of Checkpoint kinase 1 (Chk1), an emerging target for the treatment of cancer which has a key role in the DNA Damage Response (DDR). The Company is currently focusing its resources on the development of momelotinib and exploring options to support any future continued development of SRA737. The Company’s primary activities since inception have been conducting research and development activities, conducting preclinical and clinical testing, recruiting personnel, performing business and financial planning, identifying and evaluating additional drug candidates for potential in-licensing or acquisition, and raising capital to support development activities. The Company has not generated any product revenue related to its primary business purpose to date, nor has it generated any net income, and is subject to a number of risks and uncertainties, which include dependence on key individuals, the need to identify and successfully develop commercially viable products, the need to obtain regulatory approval for its products and commercialize them, and the need to obtain adequate additional financing to fund the development of momelotinib. As of September 30, 2020, the Company had $109.0 million of cash and cash equivalents. The Company believes that its balance of cash and cash equivalents as of the date of the issuance of these condensed consolidated financial statements is sufficient to fund its current operational plan for at least the next twelve months, though it may pursue raising additional capital through equity financings or other arrangements. Reverse Stock Split On January 21, 2020, the Company’s shareholders approved an amendment to the Company’s certificate of incorporation to effect a reverse split of the Company’s common stock (Reverse Stock Split). On January 21, 2020, the Company’s board of directors approved the specific ratio for the Reverse Stock Split, which became effective on January 22, 2020, at 1-for-40. The authorized shares and par value of the common and preferred stock were not adjusted as a result of the Reverse Stock Split. All issued and outstanding common stock, warrants for common stock, options for common stock and per share amounts contained in the condensed consolidated financial statements have been retroactively adjusted to reflect this Reverse Stock Split for all periods presented.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) and applicable rules and regulations of the Securities and Exchange Commission regarding interim financial reporting. Accordingly, they do not include all the information and notes required for complete financial statements and should be read in conjunction with the Company’s audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019, filed with the SEC on March 3, 2020. There were no significant changes to the accounting policies during the nine months ended September 30, 2020 from the significant accounting policies described in Note 2 to the consolidated financial statements in the 2019 Form 10-K. The unaudited condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. These unaudited condensed consolidated financial statements and related disclosure have been prepared on the same basis as the annual consolidated financial statements and reflect, in the opinion of management, all adjustments of a normal and recurring nature that are necessary for the fair presentation of the Company’s condensed consolidated financial statements included in this report. The condensed consolidated results of operations for the nine months ended September 30, 2020 are not necessarily indicative of the results to be expected for the year ending December 31, 2020, or for any other future annual or interim period. The condensed consolidated balance sheet as of December 31, 2019 included herein was derived from the audited consolidated financial statements as of that date. Use of Estimates The preparation of the condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of expense during the reporting period. Significant estimates and assumptions made in the accompanying condensed consolidated financial statements include, but are not limited to the fair value of stock options and the warrant issued, the fair value of the securities issuance obligation, the probability of achieving performance-based milestones of stock options, accruals such as research and development costs, and recoverability of the Company’s net deferred tax assets and related valuation allowance. The Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could materially differ from those estimates.

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Net Loss Per Share	3. Basic net loss per share is calculated by dividing net loss by the weighted-average number of common stock outstanding during the period without consideration for common stock equivalents. Diluted net loss per share is computed by dividing net loss by the weighted-average number of common stock equivalents outstanding for the period determined using the treasury-stock method. For purposes of this calculation, stock options and warrants for common stock are considered to be common stock equivalents and are only included in the calculation of diluted net loss per share when their effect is dilutive. The following shares of common stock equivalents were excluded from the calculation of diluted net loss per share for the periods presented because including them would have been antidilutive: September 30, 2020 September 30, 2019 Series A warrants for common stock 7,802,241 — Series B warrants for common stock 2,574,727 — Options to purchase common stock 4,246,167 328,656 Warrants for common stock 727,122 1,839 Total potential dilutive shares 15,350,257 330,495 In October 2020, the Company issued 544,868 shares of its common stock under its At-The-Market (ATM) program for proceeds of $6.5 million, net of commissions (see Note 9).

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. The Company measures and reports its cash equivalents, restricted cash, warrant liabilities and securities issuance obligation at fair value. The following table sets forth the fair value of the Company’s financial assets measured on a recurring basis by level within the fair value hierarchy: September 30, 2020 Level 1 Level 2 Level 3 Total (in thousands) Financial Assets Money market funds $ 106,277 $ — $ — $ 106,277 Restricted money market funds 300 — — 300 Total financial assets $ 106,577 $ — $ — $ 106,577 December 31, 2019 Level 1 Level 2 Level 3 Total (in thousands) Financial Assets Money market funds $ 146,240 $ — $ — $ 146,240 Restricted money market funds 300 — — 300 Total financial assets $ 146,540 $ — $ — $ 146,540 Financial Liabilities Warrant liabilities $ — $ — $ 45,935 $ 45,935 Securities issuance obligation — — 10,485 $ 10,485 Total financial liabilities $ — $ — $ 56,420 $ 56,420 Money market funds and restricted money market funds are measured at fair value on a recurring basis using quoted prices and are classified as a Level 1 input. The Company’s warrant liabilities and securities issuance obligation contained unobservable inputs that reflected the Company’s own assumptions in which there was little, if any, market activity at the measurement date. Accordingly, the Company’s warrant liabilities were measured at fair value on a recurring basis using unobservable inputs until such time the warrants were no longer considered derivative instruments. The changes in fair value of warrant liabilities were recognized as a component of other income (expense), net in the accompanying condensed consolidated statement of operations for the nine months ended September 30, 2020. The securities issuance obligation was measured at fair value on a recurring basis using unobservable inputs until the common stock and the common stock warrant were issued. The change in fair value of the securities issuance obligation was recognized as research and development expense in the accompanying condensed consolidated statement of operations for the nine months ended September 30, 2020. The warrant liabilities and the securities issuance obligation were classified as Level 3 inputs. The assumptions used in calculating the estimated fair values represented the Company’s best estimate. However, inherent uncertainties are involved. If factors or assumptions change, the estimated fair values could be materially different. On January 22, 2020, Warrant A and Warrant B were no longer considered to be derivative instruments. The Company remeasured the fair value of the warrant liabilities at the time of reclassification to equity using the following assumptions: Series A Warrant Series B Warrant Expected term (in years) 5.0 2.1 Expected volatility 43 % 88 % Risk-free interest rate 1.57 % 1.53 % Expected dividend yield — % — % On January 31, 2020, the securities issuance obligation was settled by the issuance of common stock and a common stock warrant. The Company remeasured the fair value of its common stock issuance obligation based on the value of the common stock at the time of issuance. The warrant issuance obligation was remeasured using the following assumptions: Warrant Issuance Obligation Expected term (in years) 5.0 Expected volatility 43 % Risk-free interest rate 1.57 % Expected dividend yield — % The following table provides a summary of changes in the estimated fair values of the Company’s Level 3 financial liabilities: Series A Warrant Liability Series B Warrant Liability Warrant Issuance Obligation Common Stock Issuance Obligation Total (in thousands) Balance, December 31, 2019 $ 32,616 $ 13,319 $ 3,036 $ 7,449 $ 56,420 Changes in fair value 11,597 4,643 152 1,333 17,725 Settlement of financial liabilities by securities issuance — — (3,188 ) (8,782 ) (11,970 ) Reclassification to equity (44,213 ) (17,962 ) — — (62,175 ) Balance, September 30, 2020 $ — $ — $ — $ — $ — There were no transfers between Levels 1, 2 or 3 during the nine months ended September 30, 2020.

Balance Sheet Components

Balance Sheet Components	9 Months Ended
	Sep. 30, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Balance Sheet Components	5. Cash and Cash Equivalents Cash and cash equivalents consist of the following: September 30, 2020 December 31, 2019 (in thousands) Cash $ 2,737 $ 1,288 Cash equivalents: Money market accounts 106,277 146,240 Total cash and cash equivalents $ 109,014 $ 147,528 The following table provides a reconciliation of cash, cash equivalents and restricted cash reported in the condensed consolidated balance sheets to the amounts shown in the condensed consolidated statements of cash flows. September 30, 2020 September 30, 2019 (in thousands) Cash and cash equivalents $ 109,014 $ 67,694 Restricted cash included in other assets 300 300 Total cash, cash equivalents and restricted cash shown in the condensed consolidated statement of cash flows $ 109,314 $ 67,994 Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consist of the following: September 30, 2020 December 31, 2019 (in thousands) Prepaid insurance $ 1,464 $ 918 Prepaid research and development project costs 456 853 Other receivables 328 190 Other 708 408 Total prepaid expenses and other current assets $ 2,956 $ 2,369 Property and Equipment, net Property and equipment, net consists of the following: September 30, 2020 December 31, 2019 (in thousands) Software $ 364 $ 352 Leasehold improvements 112 112 Computer equipment 89 89 Furniture and fixtures 3 3 Property and equipment, gross 568 556 Less: accumulated depreciation (505 ) (443 ) Total property and equipment, net $ 63 $ 113 Depreciation related to the Company’s property and equipment was $34,000 and $ 0.1 million for the three and nine months ended September 30, 2020 and $21,000 and $0.1 million for the three and nine months ended September 30, 2019. Accrued and Other Liabilities Accrued and other liabilities consist of the following: September 30, 2020 December 31, 2019 (in thousands) Accrued employee related costs $ 3,003 $ 3,420 Accrued research and development costs 1,648 2,668 Accrued professional fees 806 817 Operating lease liability 193 187 Other 77 78 Total accrued and other liabilities $ 5,727 $ 7,170

Leases

Leases	9 Months Ended
	Sep. 30, 2020
Leases [Abstract]
Leases	6. In June 2017, the Company entered into an operating lease agreement to lease the office space in Vancouver, Canada commencing March 1, 2018. The lease expires on February 28, 2023 and can be extended for an additional term of 5 years. The components of lease expense and related cash flows for the three and nine months ended September 30, 2020 and 2019 were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (in thousands) Operating lease cost $ 51 $ 50 $ 152 $ 152 Short-term lease cost 7 30 36 88 58 80 188 240 Operating cash flows used for operating leases $ 53 $ 53 $ 157 $ 145 As of September 30, 2020, the weighted average remaining lease term and discount rate for the operating lease are 2.4 years and 6.5%, respectively. As of September 30, 2020, maturities of lease liability due under the lease agreement are as follows: Years Ending December 31: Operating Leases (in thousands) Remainder of 2020 $ 53 2021 215 2022 171 Total lease payments 439 Less imputed interest (29 ) Total $ 410 In addition to base rent, the lease requires payment of non-lease and non-component costs. These costs are not included in the table above. As a result of prolonged office closure due to COVID-19, the Company determined the carrying value of the operating right-of-use asset was not fully recoverable. Based on current market conditions, the Company recorded an impairment charge of $0.1 million during the three months ended September 30, 2020.

Term Loan

Term Loan	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Term Loan	7. Term Loan In August 2018, the Company entered into a Loan and Security Agreement (Loan Agreement) with Silicon Valley Bank (SVB). Contemporaneously with executing the Loan Agreement, the Company drew down $5.0 million. On December 18, 2019, the Company repaid the $5.0 million term loan and paid the associated prepayment and final payment fees. In connection with the Loan Agreement, the Company issued a warrant to SVB to purchase 1,839 of the Company’s common stock at a price per share of $74.80. The warrant is immediately exercisable, will expire on August 21, 2028, contains a cashless exercise provision and is classified as equity. During the three and nine months ended September 30, 2019, the Company recognized interest expense of $0.1 million and $0.4 million, respectively.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	8 . Asset Purchase Agreement In August 2018, the Company entered into an Asset Purchase Agreement with Gilead whereby the Company acquired worldwide rights to the pharmaceutical product momelotinib, an investigational orally-bioavailable JAK1, JAK2 and ACVR1 inhibitor together with all related intellectual property rights and certain other related assets. Pursuant to the agreement, the Company made a one-time upfront payment of $3.0 million in August 2018. In October 2019, the Company entered into an amendment to the Asset Purchase Agreement in which the Company agreed to issue, subject to certain conditions, shares of common stock and a warrant to purchase common stock to Gilead in consideration for meaningfully reduced royalty rates and elimination of a near term milestone payment in the Asset Purchase Agreement. Pursuant to the amended agreement, milestone payments of up to an aggregate of $190.0 million may become payable to Gilead upon the achievement of certain regulatory and commercial milestone events and the Company is now required to pay Gilead low double-digit to high-teens percent tiered combined royalties based upon net sales. In connection with obligations under the amendment, the Company recognized a $10.5 million non-cash research and development expense for the year ended December 31, 2019 based on the fair value of the securities to be issued. On January 31, 2020, the Company fulfilled its obligation to issue securities by entering into a securities purchase agreement with Gilead, pursuant to which the Company issued to Gilead 725,283 shares of the Company’s common stock and a warrant to purchase 725,283 shares of common stock at a price per share of $13.20. The warrant is immediately exercisable, will expire on January 31, 2025 and contains a cash and/or cashless exercise provision. Upon remeasurement of the securities issuance obligation immediately prior to the issuance, an additional $1.5 million of non-cash research and development expense, representing changes in fair value of the securities since December 31, 2019, was recognized in the condensed consolidated statement of operations for the nine months ended September 30, 2020. See Note 4, Fair Value Measurement for further discussions in valuation techniques. License Agreements In September 2016, the Company entered into an exclusive license agreement with CRT Pioneer Fund LP (CPF) for worldwide rights, know-how and materials to develop SRA737, a small molecule inhibitor targeting Chk1, a promising therapeutic target to treat cancer. Pursuant to the agreement, the Company made a one-time upfront payment of $7.0 million to CPF in October 2016 and paid $2.0 million to CPF in January 2017 for the successful transfer of two ongoing Phase 1 clinical trials. Additional milestone payments of up to an aggregate of $319.5 million may become payable to CPF upon the achievement of certain developmental, regulatory and commercial milestones, including a milestone payment of $7.5 million upon the dosing of the first patient in the first Phase 1 trial of SRA737 in the United States, and a payment of $12.0 million upon the dosing of the first patient of a randomized Phase 2 trial of SRA737. In the event that the milestone payment for Phase 2 becomes due, but no milestone payment for Phase 1 has been paid, then the milestone payment for Phase 1 will become due and payable contemporaneously with the payment for the Phase 2 milestone for an aggregate payment of $19.5 million. In May 2016, the Company entered into an exclusive license agreement (Carna License Agreement) with Carna Biosciences, Inc. (Carna) for worldwide rights to develop and commercialize SRA141, a small molecule kinase inhibitor targeting Cdc7. In exchange for this exclusive right, the Company paid Carna an upfront payment of $0.9 million in June 2016. In June 2020, the Company entered into a collaboration agreement (Carna Collaboration Agreement) with Carna and terminated the Carna License Agreement. Pursuant to the Carna Collaboration Agreement, Carna paid an upfront fee of $0.3 million for the exclusive worldwide rights for SRA141 and other transition services. In addition, the Company will be entitled to single-digit royalties on product sales, on a product-by-product basis, and low to mid-teen profit share on royalty and non-royalty income. During the three months ended September 30, 2020, the Company recognized $0.1 million of collaboration revenue, representing the progress it made towards its fulfillment of the performance obligation pursuant to the Carna Collaboration Agreement. The remaining $0.2 million of the upfront fee was recorded as deferred revenue as of September 30, 2020 and will be recognized as collaboration revenue as the performance obligation is satisfied over time. Legal From time to time, the Company may become subject to other legal proceedings, claims and litigation arising in the ordinary course of business. In addition, the Company may receive letters alleging infringement of patent or other intellectual property rights. The Company is not currently a party to any other material legal proceedings, nor is it aware of any pending or threatened litigation that, in the Company’s opinion, would have a material adverse effect on the business, operating results, cash flows or financial condition should such litigation be resolved unfavorably.

Common Stock Reserved for Issua

Common Stock Reserved for Issuance	9 Months Ended
	Sep. 30, 2020
Common Stock Reserved for Issuance [Member]
Stockholders' Equity Note Disclosure	9. At-The-Market Common Stock Offering In August 2020, the Company entered into an open market sale agreement, pursuant to which it can issue and sell an aggregate of up to $20.0 million of its common stock from time to time in ATM offerings. During the three months ended September 30, 2020, the Company sold 100,000 shares under the ATM program for net proceeds of $1.1 million, net of commissions and offering expenses. Common Stock Reserved for Issuance The Company is required to reserve and keep available out of its authorized but unissued shares of common stock a number of shares sufficient to effect the conversion of all outstanding options granted and available for grant under the incentive plans, shares reserved for issuance under the employee stock purchase plan and issued warrants. September 30, 2020 December 31, 2019 Shares reserved under Series A warrant 7,802,241 7,802,241 Shares reserved under Series B warrant 2,574,727 2,574,727 Shares reserved for future option grants under equity plans 1,018,557 51,514 Outstanding stock options under equity incentive plans 4,246,167 326,023 Outstanding warrants 727,122 1,839 Shares reserved under the 2015 employee stock purchase plan 17,500 17,500 Shares reserved for conversion of Series A Preferred Stock — 7,803,273 Total common stock reserved for issuance 16,386,314 18,577,117

Preferred Stock

Preferred Stock	9 Months Ended
	Sep. 30, 2020
Preferred Stock [Member]
Stockholders' Equity Note Disclosure	10. Preferred Stock As of September 30, 2020 and December 31, 2019, the Company had 10,000,000 shares of preferred stock authorized with a par value of $0.001. There were no preferred stock outstanding as of September 30, 2020 and 103,000 shares of Series A convertible voting preferred stock (Series A Preferred Stock) outstanding as of December 31, 2019. Series A Convertible Voting Preferred Stock On November 13, 2019, the Company completed an underwritten public offering whereby it issued 103,000 shares of Series A Preferred Stock together with Series A warrants and Series B warrants for a combined purchase price of $1,000. The aggregate proceeds received by the Company was $97.7 million, net of underwriting discounts and commissions and offering expenses. Each share of Series A Preferred Stock was convertible into shares of the Company’s common stock equal to the stated value of the Series A Preferred Stock of $1,000 divided by the voting conversion price of $13.20. On January 29, 2020, all shares of Series A Preferred Stock converted into 7,803,273 shares of the Company’s common stock.

Warrant Liabilities

Warrant Liabilities	9 Months Ended
	Sep. 30, 2020
Warrants And Rights Note Disclosure [Abstract]
Warrant Liabilities	11 . Warrant Liabilities In connection with the Company’s November 2019 public offering of the Series A Preferred Stock, the Company issued Series A warrants to purchase up to 7,802,241 shares of common stock at an exercise price equal to $13.20, and Series B warrants to purchase up to 2,574,727 shares of common stock at an exercise price equal to $13.20. Both Series A and Series B warrants became exercisable, subject to certain beneficial ownership limitations, on January 22, 2020 following stockholder approval of the Reverse Stock Split which resulted in a sufficient number of authorized common stock to allow for the exercise of the warrants. The Series A warrants will expire five years from the date they first became exercisable or on January 22, 2025 and contain a cash and/or cashless exercise provision. The Series B warrants will expire on the 75th day anniversary following the announcement of top-line data from the Company’s MOMENTUM Phase 3 clinical trial of momelotinib and may only be exercised by paying the exercise price in cash, which would amount to approximately $34.0 million in proceeds to the Company if fully exercised. The fair values of the Series A and Series B warrants were classified as warrant liabilities until they ceased to be derivative instruments, following stockholder approval of the Reverse Stock split which resulted in a sufficient number of authorized common stock to allow for the exercise of the warrants, at which time they were reclassified to equity. The Company revalued the warrant liabilities until they ceased to be derivative instruments using the Black-Scholes option pricing model. The Company recorded a $16.2 million non-cash expense relating to the change in fair value of warrant liabilities in other income (expense), net in the accompanying condensed consolidated statement of operations for the nine months ended September 30, 2020 (see Note 4).

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	1 2 . The Company accounts for share-based payments at fair value, which is measured using the Black-Scholes option-pricing model. For stock-based awards that vest subject to the satisfaction of a service requirement, the fair value measurement date for stock-based compensation awards is the date of grant and the expense is recognized on a straight-line basis over the vesting period, which is generally the service period. For stock-based awards that vest subject to the satisfaction of a service requirement and a performance component, the fair value measurement date is the date of grant and is recognized over the requisite service period as achievement of the performance objective becomes probable. In the accompanying condensed consolidated statements of operations, the Company recognized stock-based compensation expense for its employees and non-employees as follows: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (in thousands) Research and development $ 1,174 $ 856 $ 2,653 $ 3,269 General and administrative 900 424 3,956 1,468 Total stock-based compensation $ 2,074 $ 1,280 $ 6,609 $ 4,737 Determination of Fair Value The fair values of the Company’s stock-based awards granted during the three and nine months ended September 30, 2020 and 2019 were estimated as of the grant date using the Black-Scholes option pricing model, based on assumptions as follows: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Expected term (in years) 5.5 – 7.0 6.0 – 6.1 5.3 – 7.0 5.3 – 6.9 Expected volatility 88 – 89 % 91 % 88 – 90 % 90 – 94 % Risk-free interest rate 0.3 – 0.5 % 1.6 % 0.3 – 1.2 % 1.6 – 2.6 % Expected dividend rate — % — % — % — % Equity Incentive Plans 2018 Equity Inducement Plan In September 2018, the Company’s Compensation Committee approved the 2018 Equity Inducement Plan (2018 Plan). The number of shares available for awards under the 2018 Plan was set to 37,500. On June 30, 2020, the Company’s Board of Directors approved an amendment to the 2018 Plan to increase the authorized number of shares available for issuance by 500,000 shares. As of September 30, 2020, 537,500 shares were reserved for issuance under the 2018 Plan. The exercise price of each stock-based award issued under the 2018 Plan is required to be no less than the fair value of the Company’s common stock. The vesting and exercise provisions of options or restricted awards granted are determined individually with each grant. Stock options have a 10-year life and expire if not exercised within that period or if not exercised within three months of cessation of employment with the Company or such longer period of time as specified in the option agreement. 2015 Plan The 2015 Equity Incentive Plan (2015 Plan) became effective on July 14, 2015. On January 21, 2020 the Company’s stockholders approved the following amendments to the 2015 Plan: (i) increase to the authorized number of shares available for issuance by 4,312,500 shares and proportionately increase the share limit related to incentive stock options, (ii) provide limits on the total value of compensation that may be granted to any non-employee director in each calendar year, and (iii) eliminate the annual individual grant limit to reflect changes to the tax law in 2017 tax legislation. As of September 30, 2020, 4,678,379 shares were reserved for issuance under the 2015 Plan. The number of shares reserved for issuance under the 2015 Plan will increase automatically on January 1 of each calendar year 2016 through 2025 by the number of shares equal to 4% of the total outstanding shares of the Company’s common stock as of the immediately preceding December 31. The Company’s Board of Directors or Compensation Committee may reduce the amount of the increase in any particular year. The exercise price of each stock-based award issued under the 2015 Plan is required to be no less than the fair value of the Company’s common stock. The vesting and exercise provisions of options or restricted awards granted are determined individually with each grant. Stock options have a 10-year life and expire if not exercised within that period or if not exercised within three months of cessation of employment with the Company or such longer period of time as specified in the option agreement, unless modified. 2008 Plan The Company granted options under the 2008 Stock Plan (2008 Plan) until July 2015 when it was terminated as to future awards, although it continues to govern the terms of options that remain outstanding under the 2008 Plan. The 2008 Plan provided for the granting of Incentive Stock Options (ISO), nonqualified stock options and stock purchase rights. In connection with the Board of Director’s approval of the 2015 Plan, all remaining shares available for future award under the 2008 Plan were transferred to the 2015 Plan, and the 2008 Plan was terminated. A summary of activity under the 2008 Plan, 2015 Plan and 2018 Plan and related information is as follows: Options Outstanding Shares Available for Grant Number of Shares Outstanding Weighted- Average Exercise Price Per Share Weighted- Average Remaining Contractual Term (Years) Aggregate Intrinsic Value of Outstanding Options (in thousands) Outstanding — December 31, 2019 51,514 326,023 $ 102.56 7.45 $ 11 Awards authorized 4,887,187 Options granted (3,965,439 ) 3,965,439 12.84 Options forfeited/cancelled 45,295 (45,295 ) 45.35 Outstanding — September 30, 2020 1,018,557 4,246,167 $ 19.38 8.71 $ 3 Exercisable — September 30, 2020 413,241 $ 70.97 3.95 $ — Vested and expected to vest — September 30, 2020 3,216,792 $ 21.53 8.83 $ 3 The weighted-average grant date fair values of options granted during the three and nine months ended September 30, 2020 was $8.85 and $8.77 per share, and $14.80 and $54.80 per share during the three and nine months ended September 30, 2019. No options were exercised for the three and nine months ended September 30, 2020. The aggregate intrinsic value of options exercised was insignificant for the three and nine months ended September 30, 2019. The total grant date fair value of options vested for the three and nine months ended September 30, 2020 was $0.7 million and $4.5 million, and $1.0 million and $5.3 million during the three and nine months ended September 30, 2019. In May 2020, the Company entered into a separation agreement with Dr. Glover, the Company’s former President and Chief Executive Officer, in connection with his resignation. Pursuant to the separation agreement, Dr. Glover’s unvested options that would have vested during the one-year period from the date of separation accelerated and vested immediately. The vesting date of all remaining unvested options accelerated by one year, and will vest in accordance with the accelerated vesting schedule as long as Dr. Glover is providing consulting services to the Company. All options that remain unvested following the termination of his consulting services will be cancelled. Furthermore, Dr. Glover received an extension of the expiration date of his vested stock options to 75 days following the Company’s announcement of the top-line data results from its MOMENTUM clinical trial. Compensation costs relating to the vesting acceleration and the modifications to option terms was nil and $2.2 million for the three and nine months ended September 30, 2020. In August 2020, the Company granted executives and employees 1,107,250 stock options with performance-based conditions. Vesting is achieved based upon the completion of pre-determined milestones. As of September 30, 2020, all of the performance-based options remain unvested. For the three and nine months ended September 30, 2020, the Company has recognized approximately $0.2 million in stock-based compensation expense related to the options with performance-based criteria. As of September 30, 2020, total unrecognized stock-based compensation related to unvested stock options with only service-vesting conditions was $24.1 million and are expected to be recognized over a remaining weighted-average period of 3.3 years. As of September 30, 2020, total unrecognized stock-based compensation related to unvested stock options with performance-based conditions was $9.7 million.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Income Taxes	1 3 . The Company did not record a provision for U.S. federal income taxes for the three and nine months ended September 30, 2020 because it expects to generate a loss for the year ended December 31, 2020. The income tax provision for the three and nine months ended September 30, 2020 represented foreign taxes. The Company’s net U.S. deferred tax assets continue to be offset by a full valuation allowance.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Use of Estimates	Error extracting Word content
Revenue Recognition	Error extracting Word content
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) and applicable rules and regulations of the Securities and Exchange Commission regarding interim financial reporting. Accordingly, they do not include all the information and notes required for complete financial statements and should be read in conjunction with the Company’s audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019, filed with the SEC on March 3, 2020. There were no significant changes to the accounting policies during the nine months ended September 30, 2020 from the significant accounting policies described in Note 2 to the consolidated financial statements in the 2019 Form 10-K. The unaudited condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. These unaudited condensed consolidated financial statements and related disclosure have been prepared on the same basis as the annual consolidated financial statements and reflect, in the opinion of management, all adjustments of a normal and recurring nature that are necessary for the fair presentation of the Company’s condensed consolidated financial statements included in this report. The condensed consolidated results of operations for the nine months ended September 30, 2020 are not necessarily indicative of the results to be expected for the year ending December 31, 2020, or for any other future annual or interim period. The condensed consolidated balance sheet as of December 31, 2019 included herein was derived from the audited consolidated financial statements as of that date.

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Schedule of Outstanding Shares of Common Stock Equivalents Excluded from Calculation of Diluted Net Loss Per Share	The following shares of common stock equivalents were excluded from the calculation of diluted net loss per share for the periods presented because including them would have been antidilutive: September 30, 2020 September 30, 2019 Series A warrants for common stock 7,802,241 — Series B warrants for common stock 2,574,727 — Options to purchase common stock 4,246,167 328,656 Warrants for common stock 727,122 1,839 Total potential dilutive shares 15,350,257 330,495

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Schedule of Fair Value Assets And Liabilities Measured On Recurring Basis	The following table sets forth the fair value of the Company’s financial assets measured on a recurring basis by level within the fair value hierarchy: September 30, 2020 Level 1 Level 2 Level 3 Total (in thousands) Financial Assets Money market funds $ 106,277 $ — $ — $ 106,277 Restricted money market funds 300 — — 300 Total financial assets $ 106,577 $ — $ — $ 106,577 December 31, 2019 Level 1 Level 2 Level 3 Total (in thousands) Financial Assets Money market funds $ 146,240 $ — $ — $ 146,240 Restricted money market funds 300 — — 300 Total financial assets $ 146,540 $ — $ — $ 146,540 Financial Liabilities Warrant liabilities $ — $ — $ 45,935 $ 45,935 Securities issuance obligation — — 10,485 $ 10,485 Total financial liabilities $ — $ — $ 56,420 $ 56,420
Schedule of Fair Value Measurement Inputs and Valuation Techniques	The Company remeasured the fair value of the warrant liabilities at the time of reclassification to equity using the following assumptions: Series A Warrant Series B Warrant Expected term (in years) 5.0 2.1 Expected volatility 43 % 88 % Risk-free interest rate 1.57 % 1.53 % Expected dividend yield — % — % Warrant Issuance Obligation Expected term (in years) 5.0 Expected volatility 43 % Risk-free interest rate 1.57 % Expected dividend yield — %
Schedule of Financial Liabilities Fair Value of Recurring Basis Using Unobservable Inputs	The following table provides a summary of changes in the estimated fair values of the Company’s Level 3 financial liabilities: Series A Warrant Liability Series B Warrant Liability Warrant Issuance Obligation Common Stock Issuance Obligation Total (in thousands) Balance, December 31, 2019 $ 32,616 $ 13,319 $ 3,036 $ 7,449 $ 56,420 Changes in fair value 11,597 4,643 152 1,333 17,725 Settlement of financial liabilities by securities issuance — — (3,188 ) (8,782 ) (11,970 ) Reclassification to equity (44,213 ) (17,962 ) — — (62,175 ) Balance, September 30, 2020 $ — $ — $ — $ — $ —

Balance Sheet Components (Table

Balance Sheet Components (Tables)	9 Months Ended
	Sep. 30, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Summary of Cash and Cash Equivalents	Cash and cash equivalents consist of the following: September 30, 2020 December 31, 2019 (in thousands) Cash $ 2,737 $ 1,288 Cash equivalents: Money market accounts 106,277 146,240 Total cash and cash equivalents $ 109,014 $ 147,528
Summary of Reconciliation of Cash, Cash Equivalents and Restricted Cash	The following table provides a reconciliation of cash, cash equivalents and restricted cash reported in the condensed consolidated balance sheets to the amounts shown in the condensed consolidated statements of cash flows. September 30, 2020 September 30, 2019 (in thousands) Cash and cash equivalents $ 109,014 $ 67,694 Restricted cash included in other assets 300 300 Total cash, cash equivalents and restricted cash shown in the condensed consolidated statement of cash flows $ 109,314 $ 67,994
Summary of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consist of the following: September 30, 2020 December 31, 2019 (in thousands) Prepaid insurance $ 1,464 $ 918 Prepaid research and development project costs 456 853 Other receivables 328 190 Other 708 408 Total prepaid expenses and other current assets $ 2,956 $ 2,369
Summary of Property and Equipment, Net	Property and equipment, net consists of the following: September 30, 2020 December 31, 2019 (in thousands) Software $ 364 $ 352 Leasehold improvements 112 112 Computer equipment 89 89 Furniture and fixtures 3 3 Property and equipment, gross 568 556 Less: accumulated depreciation (505 ) (443 ) Total property and equipment, net $ 63 $ 113
Summary of Accrued and Other Liabilities	Accrued and other liabilities consist of the following: September 30, 2020 December 31, 2019 (in thousands) Accrued employee related costs $ 3,003 $ 3,420 Accrued research and development costs 1,648 2,668 Accrued professional fees 806 817 Operating lease liability 193 187 Other 77 78 Total accrued and other liabilities $ 5,727 $ 7,170

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2020
Leases [Abstract]
Schedule of Components of Lease Expense and Related Cash Flows	The components of lease expense and related cash flows for the three and nine months ended September 30, 2020 and 2019 were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (in thousands) Operating lease cost $ 51 $ 50 $ 152 $ 152 Short-term lease cost 7 30 36 88 58 80 188 240 Operating cash flows used for operating leases $ 53 $ 53 $ 157 $ 145
Schedule of Maturities Lease Liabilities under Leases Agreement	As of September 30, 2020, maturities of lease liability due under the lease agreement are as follows: Years Ending December 31: Operating Leases (in thousands) Remainder of 2020 $ 53 2021 215 2022 171 Total lease payments 439 Less imputed interest (29 ) Total $ 410

Common Stock Reserved for Iss_2

Common Stock Reserved for Issuance (Tables)	9 Months Ended
	Sep. 30, 2020
Equity [Abstract]
Schedule of Common Stock Reserved for Issuance	At-The-Market Common Stock Offering In August 2020, the Company entered into an open market sale agreement, pursuant to which it can issue and sell an aggregate of up to $20.0 million of its common stock from time to time in ATM offerings. During the three months ended September 30, 2020, the Company sold 100,000 shares under the ATM program for net proceeds of $1.1 million, net of commissions and offering expenses. Common Stock Reserved for Issuance The Company is required to reserve and keep available out of its authorized but unissued shares of common stock a number of shares sufficient to effect the conversion of all outstanding options granted and available for grant under the incentive plans, shares reserved for issuance under the employee stock purchase plan and issued warrants. September 30, 2020 December 31, 2019 Shares reserved under Series A warrant 7,802,241 7,802,241 Shares reserved under Series B warrant 2,574,727 2,574,727 Shares reserved for future option grants under equity plans 1,018,557 51,514 Outstanding stock options under equity incentive plans 4,246,167 326,023 Outstanding warrants 727,122 1,839 Shares reserved under the 2015 employee stock purchase plan 17,500 17,500 Shares reserved for conversion of Series A Preferred Stock — 7,803,273 Total common stock reserved for issuance 16,386,314 18,577,117

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Stock-based Compensation Expense for Employees and Non-employees	In the accompanying condensed consolidated statements of operations, the Company recognized stock-based compensation expense for its employees and non-employees as follows: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (in thousands) Research and development $ 1,174 $ 856 $ 2,653 $ 3,269 General and administrative 900 424 3,956 1,468 Total stock-based compensation $ 2,074 $ 1,280 $ 6,609 $ 4,737
Schedule of Estimated Grant-date Fair Value of Stock-based Awards Using Black-Scholes Option Pricing Model Assumptions	Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Expected term (in years) 5.5 – 7.0 6.0 – 6.1 5.3 – 7.0 5.3 – 6.9 Expected volatility 88 – 89 % 91 % 88 – 90 % 90 – 94 % Risk-free interest rate 0.3 – 0.5 % 1.6 % 0.3 – 1.2 % 1.6 – 2.6 % Expected dividend rate — % — % — % — %
Summary of Stock-Based Compensation Activity	A summary of activity under the 2008 Plan, 2015 Plan and 2018 Plan and related information is as follows: Options Outstanding Shares Available for Grant Number of Shares Outstanding Weighted- Average Exercise Price Per Share Weighted- Average Remaining Contractual Term (Years) Aggregate Intrinsic Value of Outstanding Options (in thousands) Outstanding — December 31, 2019 51,514 326,023 $ 102.56 7.45 $ 11 Awards authorized 4,887,187 Options granted (3,965,439 ) 3,965,439 12.84 Options forfeited/cancelled 45,295 (45,295 ) 45.35 Outstanding — September 30, 2020 1,018,557 4,246,167 $ 19.38 8.71 $ 3 Exercisable — September 30, 2020 413,241 $ 70.97 3.95 $ — Vested and expected to vest — September 30, 2020 3,216,792 $ 21.53 8.83 $ 3

The Company and Basis of Pres_2

The Company and Basis of Presentation - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Cash and cash equivalents	$ 109,014	$ 147,528	$ 67,694

Net Loss Per Share - Schedule o

Net Loss Per Share - Schedule of Outstanding Shares of Common Stock Equivalents Excluded from Calculation of Diluted Net Loss Per Share (Detail) - shares	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potential dilutive shares	15,350,257	330,495
Series A Warrants For Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potential dilutive shares	7,802,241
Series B Warrants For Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potential dilutive shares	2,574,727
Stock options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potential dilutive shares	4,246,167	328,656
Warrants for Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potential dilutive shares	727,122	1,839

Net Loss Per Share - Additional

Net Loss Per Share - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	9 Months Ended
	Oct. 31, 2020	Sep. 30, 2020	Sep. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Proceeds from issuance of common stock			$ 1,140
ATM Program [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Issuance of common stock, Shares	544,868	100,000	100,000
Proceeds from issuance of common stock	$ 6,500

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value of Financial Assets Measured on Recurring Basis (Detail) - Fair Value Measurements Recurring [Member] - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Financial Assets
Total financial assets	$ 106,577	$ 146,540
Financial Liabilities
Total financial liabilities		56,420
Warrant liabilities [Member]
Financial Liabilities
Total financial liabilities		45,935
Securities issuance obligation [Member]
Financial Liabilities
Total financial liabilities		10,485
Level 1 [Member]
Financial Assets
Total financial assets	106,577	146,540
Level 3 [Member]
Financial Liabilities
Total financial liabilities		56,420
Level 3 [Member] | Warrant liabilities [Member]
Financial Liabilities
Total financial liabilities		45,935
Level 3 [Member] | Securities issuance obligation [Member]
Financial Liabilities
Total financial liabilities		10,485
Money Market Funds [Member]
Financial Assets
Total financial assets	106,277	146,240
Money Market Funds [Member] | Level 1 [Member]
Financial Assets
Total financial assets	106,277	146,240
Restricted Money Market Funds [Member]
Financial Assets
Total financial assets	300	300
Restricted Money Market Funds [Member] | Level 1 [Member]
Financial Assets
Total financial assets	$ 300	$ 300

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Fair Value of Financial Liabilities Assumptions (Detail)	Jan. 31, 2020yr	Jan. 22, 2020yr
Expected term [Member] | Series A Warrant [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input		5
Expected term [Member] | Series B Warrant [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input		2.1
Expected term [Member] | Warrant Issuance Obligation [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	5
Expected volatility [Member] | Series A Warrant [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input		0.43
Expected volatility [Member] | Series B Warrant [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input		0.88
Expected volatility [Member] | Warrant Issuance Obligation [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.43
Risk-free interest rate [Member] | Series A Warrant [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input		0.0157
Risk-free interest rate [Member] | Series B Warrant [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input		0.0153
Risk-free interest rate [Member] | Warrant Issuance Obligation [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.0157

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of Changes in Fair Values Level Financial Liabilities Recurring Basis Using Unobservable Inputs (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Mar. 31, 2020	Sep. 30, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Reclassification of warrant liabilities to equity	$ 62,175	$ 62,175
Changes in fair value of warrant liabilities		16,240
Fair Value Measurements Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Beginning Balance	56,420	56,420
Changes in fair value		17,725
Settlement of financial liabilities by securities issuance		(11,970)
Reclassification of warrant liabilities to equity		(62,175)
Fair Value Measurements Recurring [Member] | Series A Warrant [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Beginning Balance	32,616	32,616
Changes in fair value of warrant liabilities		11,597
Reclassification to equity		(44,213)
Fair Value Measurements Recurring [Member] | Series B Warrant [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Beginning Balance	13,319	13,319
Changes in fair value of warrant liabilities		4,643
Reclassification to equity		(17,962)
Fair Value Measurements Recurring [Member] | Warrant Issuance Obligation [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Beginning Balance	3,036	3,036
Settlement of financial liabilities by securities issuance		(3,188)
Changes in fair value		152
Fair Value Measurements Recurring [Member] | Common stock Issuance Obligation [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Beginning Balance	$ 7,449	7,449
Settlement of financial liabilities by securities issuance		(8,782)
Changes in fair value		$ 1,333

Balance Sheet Components - Summ

Balance Sheet Components - Summary of Cash and Cash Equivalents (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Cash And Cash Equivalents [Abstract]
Cash	$ 2,737	$ 1,288
Cash equivalents:
Money market accounts	106,277	146,240
Total cash and cash equivalents	$ 109,014	$ 147,528	$ 67,694

Balance Sheet Components - Su_2

Balance Sheet Components - Summary of Reconciliation of Cash, Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Cash And Cash Equivalents [Abstract]
Cash and cash equivalents	$ 109,014	$ 147,528	$ 67,694
Restricted cash included in other assets	300		300
Total cash, cash equivalents and restricted cash shown in the condensed consolidated statement of cash flows	$ 109,314	$ 147,828	$ 67,994	$ 106,346

Balance Sheet Components - Su_3

Balance Sheet Components - Summary of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Prepaid insurance	$ 1,464	$ 918
Prepaid research and development project costs	456	853
Other receivables	328	190
Other	708	408
Total prepaid expenses and other current assets	$ 2,956	$ 2,369

Balance Sheet Components - Su_4

Balance Sheet Components - Summary of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 568	$ 556
Less: accumulated depreciation	(505)	(443)
Total property and equipment, net	63	113
Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	364	352
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	112	112
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	89	89
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 3	$ 3

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Property Plant And Equipment [Abstract]
Depreciation	$ 34,000	$ 21,000	$ 100,000	$ 100,000

Balance Sheet Components - Su_5

Balance Sheet Components - Summary of Accrued and Other Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Accrued employee related costs	$ 3,003	$ 3,420
Accrued research and development costs	1,648	2,668
Accrued professional fees	806	817
Operating lease liability	193	187
Other	77	78
Total accrued and other liabilities	$ 5,727	$ 7,170

Leases - Additional Information

Leases - Additional Information (Detail) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2020USD ($)
Leases [Abstract]
Operating lease agreement expiration date		Feb. 28, 2023
Additional lease term to be extended	5 years	5 years
Weighted-average remaining lease term, operating lease (Year)	2 years 4 months 24 days	2 years 4 months 24 days
Weighted-average discount rate, Operating lease	6.50%	6.50%
Asset impairment	$ 100	$ 106

Leases - Schedule of Components

Leases - Schedule of Components of Lease Expense and Related Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Leases [Abstract]
Operating lease cost	$ 51	$ 50	$ 152	$ 152
Short-term lease cost	7	30	36	88
Total Lease Cost	58	80	188	240
Operating cash flows used for operating leases	$ 53	$ 53	$ 157	$ 145

Leases - Schedule of Maturities

Leases - Schedule of Maturities Lease Liabilities under Leases Agreement (Detail) $ in Thousands	Sep. 30, 2020USD ($)
Leases [Abstract]
Remainder of 2020	$ 53
2021	215
2022	171
Total lease payments	439
Less imputed interest	(29)
Total	$ 410

Term Loan - Additional Informat

Term Loan - Additional Information (Detail) - Silicon Valley Bank [Member] - Term Loans [Member] - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 18, 2019	Aug. 31, 2018
Debt Instrument [Line Items]
Loan agreement, description			Contemporaneously with executing the Loan Agreement, the Company drew down $5.0 million.
Interest expense	$ 0	$ 0.1	$ 0	$ 0.4
Warrants to Purchase Common Stock [Member]
Debt Instrument [Line Items]
Warrants issued in connection with loan			1,839
Excercise price of warrants or rights	$ 74.80		$ 74.80
Warrant expiration date						Aug. 21, 2028
Tranche One [Member]
Debt Instrument [Line Items]
Aggregate principal amount of loans					$ 5
Amount borrowed	$ 5		$ 5

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended				3 Months Ended	9 Months Ended	12 Months Ended
	Jan. 31, 2020	Aug. 31, 2018	Oct. 31, 2016	Jun. 30, 2016	Sep. 30, 2020	Sep. 30, 2020	Dec. 31, 2019	Jan. 31, 2017
Loss Contingencies [Line Items]
Collaboration revenue					$ 100	$ 100
Deferred Revenue					200	200
Carna Collaboration Agreement [Member]
Loss Contingencies [Line Items]
Upfront License Fee						300
Collaboration revenue					100
Deferred Revenue					200	200
Asset Purchase Agreement [Member]
Loss Contingencies [Line Items]
Upfront payment paid		$ 3,000
Aggregate milestone payment						190,000
Expense included research and development cost							$ 10,500
Additional expense included research and development cost						1,500
Asset Purchase Agreement Amendment [Member] | Gilead [Member]
Loss Contingencies [Line Items]
Stock issued, shares	725,283
Number of securities called by warrants and rights	725,283
Excercise price of warrants or rights	$ 13.20
CPF License Agreements [Member]
Loss Contingencies [Line Items]
Aggregate milestone payment						19,500
Upfront payment paid			$ 7,000
Milestone payment								$ 2,000
Additional milestone payment payable						319,500
CPF License Agreements [Member] | Phase 1 Clinical Trial in the US [Member]
Loss Contingencies [Line Items]
Milestone payment					7,500	7,500
CPF License Agreements [Member] | Phase Two Clinical Trial [Member]
Loss Contingencies [Line Items]
Milestone payment					$ 12,000	$ 12,000
Carna License Agreement [Member]
Loss Contingencies [Line Items]
Upfront payment paid				$ 900

Common Stock Reserved for Iss_3

Common Stock Reserved for Issuance - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Oct. 31, 2020	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2020	Aug. 31, 2020
Class of Stock [Line Items]
Issuance of common stock		$ 1,140,000	$ 8,782,000
ATM Program [Member]
Class of Stock [Line Items]
Issuance of common stock, Shares	544,868	100,000		100,000
Issuance of common stock		$ 1,100,000		$ 1,100,000
ATM Program [Member] | Maximum [Member]
Class of Stock [Line Items]
Common stock reserved for issuance					$ 20,000,000

Common Stock Reserved for Iss_4

Common Stock Reserved for Issuance - Schedule of Common Stock Reserved for Issuance (Detail) - shares	Sep. 30, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Total common stock reserved for future issuance	16,386,314	18,577,117
Series A Warrant [Member]
Class of Stock [Line Items]
Total common stock reserved for future issuance	7,802,241	7,802,241
Series B Warrant [Member]
Class of Stock [Line Items]
Total common stock reserved for future issuance	2,574,727	2,574,727
Equity Incentive Plans [Member]
Class of Stock [Line Items]
Total common stock reserved for future issuance	1,018,557	51,514
Awards outstanding	4,246,167	326,023
2015 Employee Stock Purchase Plan [Member]
Class of Stock [Line Items]
Total common stock reserved for future issuance	17,500	17,500
Warrants to Purchase Common Stock [Member]
Class of Stock [Line Items]
Outstanding warrants	727,122	1,839
Series A Preferred Stock [Member]
Class of Stock [Line Items]
Total common stock reserved for future issuance		7,803,273

Preferred Stock - Additional in

Preferred Stock - Additional information (Detail) - USD ($) $ / shares in Units, $ in Millions	Nov. 13, 2019	Sep. 30, 2020	Jan. 29, 2020	Dec. 31, 2019
Series A Convertible Voting Preferred Stock [Member]
Preferred stock, shares authorized		10,000,000		10,000,000
Preferred stock, par value		$ 0.001		$ 0.001
Preferred stock, shares outstanding		0		103,000
Stock issued, shares	103,000
Preferred Stock converted into of the Company's common stock			7,803,273
Convertible Preferred Stock And Warrants And Underwritten Follow On Offering [Member]
Share issued price per share	$ 1,000
Proceeds from issuance of convertible preferred stock and warrants net of issuance cost	$ 97.7
Series A Preferred Stock [Member]
Share issued price per share		$ 1,000
Preferred stock conversion price per share		$ 13.20

Warrant Liabilities - Additiona

Warrant Liabilities - Additional information (Detail) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020$ / sharesshares	Sep. 30, 2020USD ($)$ / sharesshares
Class of Warrant or Right [Line Items]
Non-cash expense on warrant liability | $		$ 16,240
Series A Warrants [Member]
Class of Warrant or Right [Line Items]
Warrant expiration period after specified event	5 years	5 years
Series B Warrants [Member]
Class of Warrant or Right [Line Items]
Warrant expiration period after specified event	75 days	75 days
Exercise of Future Warrants Value | $		$ 34,000
Underwritten Follow On Offerings [Member] | Series A Warrants [Member]
Class of Warrant or Right [Line Items]
Number of securities called by warrants and rights | shares	7,802,241	7,802,241
Excercise price of warrants or rights | $ / shares	$ 13.20	$ 13.20
Underwritten Follow On Offerings [Member] | Series B Warrants [Member]
Class of Warrant or Right [Line Items]
Number of securities called by warrants and rights | shares	2,574,727	2,574,727
Excercise price of warrants or rights | $ / shares	$ 13.20	$ 13.20

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Stock-based Compensation Expense for Employees and Non-employees (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	$ 2,074	$ 1,280	$ 6,609	$ 4,737
Research and development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	1,174	856	2,653	3,269
General and administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	$ 900	$ 424	$ 3,956	$ 1,468

Stock-Based Compensation - Sc_2

Stock-Based Compensation - Schedule of Estimated Grant-date Fair Values of Stock-based Awards Using Black-Scholes Option Pricing Model Assumptions (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, Minimum	88.00%	91.00%	88.00%	90.00%
Expected volatility, Maximum	89.00%		90.00%	94.00%
Risk-free interest rate, Minimum	0.30%	1.60%	0.30%	1.60%
Risk-free interest rate, Maximum	0.50%		1.20%	2.60%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	5 years 6 months	6 years	5 years 3 months 18 days	5 years 3 months 18 days
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	7 years	6 years 1 month 6 days	7 years	6 years 10 months 24 days

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Jan. 21, 2020	Aug. 31, 2020	May 31, 2020	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock shares reserved for issuance				16,386,314			16,386,314		18,577,117
Total stock-based compensation				$ 2,074	$ 1,280		$ 6,609	$ 4,737
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Executives and employees stock options granted		1,107,250
Total stock-based compensation				200			200
Total unrecognized stock-based compensation related to unvested stock options				9,700			9,700
Service Vesting Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized stock-based compensation related to unvested stock options				$ 24,100			$ 24,100
Weighted-average period							3 years 3 months 18 days
2018 Equity Inducement Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock shares reserved for issuance				537,500			537,500			37,500
Common shares authorized to be issued during the period						500,000
Stock option life in years							10 years
2015 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock shares reserved for issuance				4,678,379			4,678,379
Common shares authorized to be issued during the period	4,312,500
Stock option life in years							10 years
Percentage threshold of outstanding shares increased annually under the plan							4.00%
Stock option grants description							The number of shares equal to 4% of the total outstanding shares of the Company’s common stock as of the immediately preceding December 31.
2015 Plan [Member] | Contract Termination [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrant expiration period after specified event			75 days
2008 Plan, 2015 Plan and 2018 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares authorized to be issued during the period							4,887,187
Weighted-average grant date fair values of options granted				$ 8.85	$ 14.80		$ 8.77	$ 54.80
Issuance of common stock for exercise of stock options, Shares				0			0
Total grant date fair value of options vested				$ 700	$ 1,000		$ 4,500	$ 5,300
2018 Plan [Member] | Contract Termination [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation costs relating to vesting acceleration and modification							$ 2,200

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock-Based Compensation Activity (Detail) - 2008 Plan, 2015 Plan and 2018 Plan [Member] - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Options Outstanding, Shares Available for Grant
Shares Available for Grant, Beginning balance	51,514
Shares Available for Grant, Awards authorized	4,887,187
Shares Available for Grant, Granted	(3,965,439)
Shares Available for Grant, forfeited/cancelled	45,295
Shares Available for Grant, Ending balance	1,018,557	51,514
Options Outstanding, Number of Shares Outstanding
Number of Shares Outstanding, Beginning balance	326,023
Number of Shares Outstanding, Options granted	3,965,439
Number of Shares Outstanding, Options forfeited/cancelled	(45,295)
Number of Shares Outstanding, Ending balance	4,246,167	326,023
Number of Shares Outstanding, Exercisable	413,241
Number of Shares Outstanding, Vested and expected to vest	3,216,792
Options Outstanding, Weighted-Average Exercise Price Per Share
Weighted-Average Exercise Price Per Share, Beginning balance	$ 102.56
Weighted-Average Exercise Price Per Share, Options granted	12.84
Weighted-Average Exercise Price Per Share, Options forfeited/cancelled	45.35
Weighted-Average Exercise Price Per Share, Ending balance	19.38	$ 102.56
Weighted-Average Exercise Price Per Share, Exercisable	70.97
Weighted-Average Exercise Price Per Share, Vested and expected to vest	$ 21.53
Options Outstanding, Weighted-Average Remaining Contractual Term (Years)
Weighted-Average Remaining Contractual Term (Years)	8 years 8 months 15 days	7 years 5 months 12 days
Weighted-Average Remaining Contractual Term (Year), Exercisable	3 years 11 months 12 days
Weighted-Average Remaining Contractual Term (Year), Vested and expected to vest	8 years 9 months 29 days
Options Outstanding, Aggregate Intrinsic Value of Outstanding Options
Aggregate Intrinsic Value of Outstanding Options	$ 3	$ 11
Aggregate Intrinsic Value of Outstanding Options, Vested and expected to vest	$ 3

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Federal income tax provision, continuing operations	$ 0	$ 0