Viracta Therapeutics (VIRX) 10-K 24 Feb 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 18, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Registrant Name	SUNESIS PHARMACEUTICALS INC.
Entity Central Index Key	0001061027
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Public Float			$ 28,910,000
Entity Common Stock, Shares Outstanding		18,108,000
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Entity File Number	000-51531
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	94-3295878
Entity Address, Address Line One	395 Oyster Point Boulevard
Entity Address, Address Line Two	Suite 400
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94080
City Area Code	650
Local Phone Number	266-3500
Document Annual Report	true
Document Transition Report	false
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol:	SNSS
Security Exchange Name	NASDAQ
Documents Incorporated by Reference	None.

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 20,410	$ 12,761
Restricted cash		5,500
Marketable securities		16,364
Prepaids and other current assets	1,734	1,697
Total current assets	22,144	36,322
Property and equipment, net		3
Operating lease - right-of-use asset	273	817
Other assets	830	98
Total assets	23,247	37,240
Current liabilities:
Accounts payable	479	791
Accrued clinical expense	87	521
Accrued compensation	1,384	985
Other accrued liabilities	1,087	1,109
Notes payable		5,465
Operating lease liability - current	273	545
Total current liabilities	3,310	9,416
Other liabilities		9
Operating lease liability - long term		272
Total liabilities	3,310	9,697
Commitments and contingencies (Note 8)
Stockholders’ equity:
Convertible preferred stock, $0.0001 par value; 10,000 shares authorized as of December 31, 2020; 10 and 20 shares issued and outstanding as of December 31, 2020 and 2019, respectively	5,545	11,769
Common stock, $0.0001 par value; 400,000 shares authorized as of December 31, 2019; 18,108 and 11,139 shares issued and outstanding as of December 31, 2020 and 2019, respectively	2	1
Additional paid-in capital	718,800	698,572
Accumulated other comprehensive income		1
Accumulated deficit	(704,410)	(682,800)
Total stockholders’ equity	19,937	27,543
Total liabilities and stockholders’ equity	$ 23,247	$ 37,240

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	10,000	20,000
Preferred stock, shares outstanding	10,248	19,714
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	18,108,000	11,139,000
Common stock, shares outstanding	18,108,000	11,139,000

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Revenue:
License and other revenue	$ 120	$ 2,073
Type of Revenue [Extensible List]	snss:LicenseAndOtherRevenueMember	snss:LicenseAndOtherRevenueMember
Operating expenses:
Research and development	$ 12,259	$ 15,412
General and administrative	10,164	9,949
Total operating expenses	22,423	25,361
Loss from operations	(22,303)	(23,288)
Interest expense	(302)	(514)
Other income, net	995	472
Net loss	(21,610)	(23,330)
Unrealized (loss) and gain on available-for-sale securities	(1)	1
Comprehensive loss	(21,611)	(23,329)
Basic and diluted loss per common share:
Net loss:	$ (21,610)	$ (23,330)
Shares used in computing net basic and diluted loss per common share:	14,093	8,712
Net loss per common share:	$ (1.53)	$ (2.68)

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Beginning Balance at Dec. 31, 2018	$ 3,993	$ 20,998		$ 642,464		$ (659,469)
Beginning Balance, shares at Dec. 31, 2018		18,000	3,747,000
Issuance of common stock, preferred stock, net of issuance cost	44,604	$ 12,533	$ 1	32,070
Issuance of common stock, preferred stock, net of issuance cost, shares		25,000	6,133,000
Issuance of common stock upon conversion of preferred stock		$ (21,762)		21,762
Issuance of common stock upon conversion of preferred stock, shares		(23,000)	1,195,000
Issuance of common stock through controlled equity offering facilities, net of issuance costs	464			464
Issuance of common stock through controlled equity offering facilities, net of issuance costs, shares			40,000
Issuance of common stock from vesting of restricted stock awards	54			54
Issuance of common stock from vesting of restricted stock awards, shares			11,000
Issuance of common stock under employee stock purchase plans	63			63
Issuance of common stock under employee stock purchase plans, shares			13,000
Stock-based compensation expenses	1,695			1,695
Net loss	(23,330)
Net loss | ASU 2018-07 [Member]	(23,331)					(23,331)
Unrealized (loss) and gain on available-for-sale securities	1				$ 1
Ending Balance at Dec. 31, 2019	27,543	$ 11,769	$ 1	698,572	1	(682,800)
Ending Balance, shares at Dec. 31, 2019		20,000	11,139,000
Issuance of common stock, preferred stock, net of issuance cost	12,633		$ 1	12,632
Issuance of common stock, preferred stock, net of issuance cost, shares			6,000,000
Issuance of common stock upon conversion of preferred stock		$ (6,224)		6,224
Issuance of common stock upon conversion of preferred stock, shares		(10,000)	946,600
Issuance of common stock under employee stock purchase plans	48			48
Issuance of common stock under employee stock purchase plans, shares			22,000
Stock-based compensation expenses	1,324			1,324
Net loss	(21,610)					(21,610)
Unrealized (loss) and gain on available-for-sale securities	(1)				$ (1)
Ending Balance at Dec. 31, 2020	$ 19,937	$ 5,545	$ 2	$ 718,800		$ (704,410)
Ending Balance, shares at Dec. 31, 2020		10,000	18,108,000

CONSOLIDATED STATEMENTS OF ST_2

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Statement Of Stockholders Equity [Abstract]
Issuance of common stock	$ 13,800	$ 38,000
Issuance of preferred stock		10,000
Issuance of common stock, preferred stock, issuance cost	$ 1,167	3,400
Issuance of common stock through controlled equity offering facilities		473
Issuance of common stock through controlled equity offering facilities, issuance costs		$ 9

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities
Net loss	$ (21,610)	$ (23,330)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	1,324	1,749
Accretion of investment discounts and depreciation	(41)	(70)
Amortization of debt discount and debt issuance costs	35	116
Gain on conversion of note receivable to equity investments	(830)
Changes in operating assets and liabilities:
Prepaids and other assets	61	(294)
Accounts payable	(312)	(602)
Accrued clinical expense	(434)	21
Accrued compensation	399	42
Other accrued liabilities	(31)	183
Net cash used in operating activities	(21,439)	(22,185)
Cash flows from investing activities
Purchases of marketable securities	(747)	(20,035)
Sale and maturities of marketable securities	17,154	3,750
Net cash provided by (used in) investing activities	16,407	(16,285)
Cash flows from financing activities
Proceeds from notes payable, net of issuance cost		5,453
Principal payments on notes payable	(5,500)	(7,500)
Proceeds from issuance of convertible preferred stock offering, net		12,533
Proceeds from issuance of common stock, net	12,633	32,022
Proceeds from issuance of common stock through controlled equity offering facilities, net		464
Proceeds from exercise of stock options and stock purchase rights	48	63
Net cash provided by financing activities	7,181	43,035
Net increase in cash and cash equivalents	2,149	4,565
Cash, cash equivalents and restricted cash at beginning of period	18,261	13,696
Cash, cash equivalents and restricted cash at end of period	20,410	18,261
Supplemental disclosure of cash flow information
Interest paid	339	695
Supplemental disclosure of non-cash investing and financing activities
Conversion of preferred stock to common stock	6,224	21,762
Conversion of notes receivable to equity investments	$ 830
Right-of-use asset obtained in exchange for lease obligation		$ 1,362

Company Overview

Company Overview	12 Months Ended
	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Company Overview	1. Company Overview Description of Business Sunesis Pharmaceuticals, Inc. (“Sunesis” or the “Company”) is a biopharmaceutical company focused on the development of novel targeted inhibitors for the treatment of hematologic and solid cancers. Sunesis is developing SNS-510, a PDK1 inhibitor licensed from Millennium Pharmaceuticals, Inc. (“Takeda Oncology”), a wholly-owned subsidiary of Takeda Pharmaceutical Company Limited. SNS-510 interaction with PDK1 inhibits both PI3K-dependent and independent signaling pathways integral to many malignancies, and PDK1 can also be overexpressed in breast, lung, prostate, hematologic and other cancers. Evaluation of SNS-510 in the Eurofins Oncopanel™, a panel of >300 genomically profiled cancer cell lines from diverse tissue origins, indicated that tumors with mutations or deletions of the Cyclin Dependent Kinase Inhibitor 2A (“CDKN2A”) gene are particularly sensitive to SNS-510. CDKN2A alterations are common in human cancers and may prove to be useful biomarkers for broad investigation of SNS-510 as a monotherapy and in combination with other anticancer agents. In other in vitro studies, SNS-510 had strong activity against a broad range of sarcoma cell lines. SNS-510 showed synergistic activity when combined with inhibitors of CDK4/6, KRAS G12C, or BCL-2 in breast cancer, sarcoma, KRAS-mutant, and lymphoma cell lines. In in vivo studies, SNS-510 demonstrated potent, pathway-mediated antitumor activity in FLT3-mutated and wild-type AML xenograft mouse models, as well as in a myc-activated, CDKN2A-deleted lymphoma xenograft mouse model. Sunesis is completing reporting of Investigational New Drug-enabling studies for SNS-510 and is evaluating the next steps for the program. Sunesis’s second program is vecabrutinib, a selective non-covalent inhibitor of Bruton’s Tyrosine Kinase (“BTK”) with activity against both wild-type and C481S-mutated BTK, the most common mutation associated with resistance to covalent BTK inhibitors. In June 2020, Sunesis announced that it will not advance its non-covalent BTK inhibitor vecabrutinib in the planned Phase 2 portion of the Phase 1b/2 trial for adults with relapsed or refractory chronic lymphocytic leukemia (“CLL”) and other B-cell malignancies. The decision was made after assessing the totality of the data including the 500 mg cohort, the highest dose studied in the trial, as Sunesis found insufficient evidence of activity in BTK-inhibitor resistant disease to move the program into Phase 2. Sunesis has completed the Phase 1b portion of the Phase 1b/2 trial and is evaluating the best path forward for vecabrutinib. Sunesis also has two partnered programs: DAY101 (formerly TAK-580) and vosaroxin. Sunesis has a license agreement with DOT Therapeutics-1 (“DOT-1”), where Sunesis is eligible to receive potential pre-commercialization, event-based milestone payments and royalty payments on future sales of DAY101, when and if approved and commercialized. In addition, Sunesis has a license agreement with Denovo Biopharma (“Denovo”) where Sunesis is eligible to receive potential regulatory and commercial milestones, and royalties on future sales of vosaroxin, when and if approved and commercialized. To conserve its cash resources, Sunesis has substantially reduced its workforce and has reduced its research and development activities. In July 2020, Sunesis reduced its workforce by 30% to focus on development of its PDK1 inhibitor SNS-510 while evaluating its strategic alternatives with a goal to enhance stockholder value, including asset in-licensing, partnering, and mergers and acquisitions. Sunesis recognized one-time employee severance expenses of The Sunesis Board commenced a process of evaluating strategic alternatives to maximize stockholder value. To assist with this process, the Sunesis Board engaged MTS Health Partners, L.P. to help explore Sunesis’s available strategic alternatives, including possible mergers and business combinations, a sale of part or all of Sunesis’s assets, and collaboration and licensing arrangements. On November 30, 2020, Sunesis and Viracta Therapeutics, Inc. (“Viracta”) announced the signing of an Agreement and Plan of Merger and Reorganization, dated November 29, 2020, as may be amended from time to time (the “Merger Agreement”). Upon the terms and subject to the satisfaction of the conditions described in the Merger Agreement, including approval of the transaction by Sunesis’s stockholders, a wholly owned subsidiary of Sunesis will be merged with and into Viracta, with Viracta surviving the Merger as a wholly-owned subsidiary of Sunesis (the “Merger”). On December 18, 2020, due to the entry into the Merger Agreement, Sunesis reduced its workforce by approximately 40% to preserve cash resources while completing the proposed Merger. As a result of the workforce reduction, Sunesis recognized one-time employee severance expenses of $1.3 million, which were included in accrued compensation on the consolidated balance sheet as of December 31, 2020, and noncash stock compensation expenses related to accelerated vesting of certain employee stock options of $0.1 million, both of which were recorded as operating expenses on the consolidated statement of operations and comprehensive loss for the year ended December 31, 2020. Liquidity and Going Concern The Company has incurred significant losses and negative cash flows from operations since its inception, and as of December 31, 2020, had cash and cash equivalents totaling $20.4 million and an accumulated deficit of $704.4 million. The Company expects to continue to incur significant losses for the foreseeable future as it continues development of its kinase inhibitor pipeline, including its PDK1 inhibitor, SNS-510. The Company’s cash and cash equivalents are not sufficient to support its operations for a period of twelve months from the date these consolidated financial statements are available to be issued. These factors raise substantial doubt about its ability to continue as a going concern. The Company will require additional financing to fund working capital and pay its obligations as they come due. Additional financing might include one or more offerings and one or more of a combination of equity securities, debt arrangements or partnership or licensing collaborations. However, there can be no assurance that the Company will be successful in completing the Merger or acquiring additional funding at levels sufficient to fund its operations or on terms favorable to the Company. If the Company is unsuccessful in its efforts to complete the Merger, seek other strategic alternatives or raise additional financing in the near term, the Company will be required to significantly reduce or cease operations. The accompanying consolidated financial statements have been prepared assuming the Company will continue to operate as a going concern, which contemplates the realization of assets and the settlement of liabilities in the normal course of business. The consolidated financial statements do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts of liabilities that may result from uncertainty related to the Company’s ability to continue as a going concern . Concentrations of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk generally consist of cash and cash equivalents. The Company is exposed to credit risk in the event of default by the institutions holding its cash and cash equivalents to the extent of the amounts recorded in the balance sheets.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”). Reverse Stock Split On September 2, 2020, the Company effected a one-for-ten reverse split of its outstanding common stock (the "Reverse Split"), as previously authorized and approved at the annual meeting of stockholders on June 16, 2020. As a result of the Reverse Split, every ten shares of common stock were combined into one share of common stock. The Reverse Split affected the shares of Company's common stock: (a) outstanding immediately prior to the effective time of the Reverse Split, (b) available for issuance under the Company's equity incentive plans, (c) issuable upon the exercise of outstanding stock options and warrants and (d) issuable upon conversion of the outstanding non-voting Series E and Series F Convertible Preferred Stock. All share and per-share data in the Company’s consolidated financial statements and notes thereto give retroactive effect to the Reverse Split for all periods presented. Adopted Accounting Pronouncements In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement Recent Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instruments Codification Improvements to Topic 326, Financial Instruments—Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments Financial Instruments—Credit Losses, Topic 326 Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842): Effective Dates Codification Improvements to Topic 326, Financial Instruments—Credit Losses, In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. In August 2020, the FASB issued ASU No. 2020-06, Debt – Debt with Conversion and Other options (Subtopic 470-20) and Derivative and Hedging – Contracts in Entity’s Own Equity (Subtopic 815-40). Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly owned subsidiary, Sunesis Europe Limited, a United Kingdom corporation. All intercompany balances and transactions have been eliminated in consolidation. Segment Reporting Management has determined that the Company operates as a single reportable segment. Significant Estimates and Judgments The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the Company’s consolidated financial statements and accompanying notes thereto. Actual results could differ materially from these estimates. Estimates, assumptions and judgments made by management include those related to the valuation of marketable securities, equity and related instruments, revenue recognition, stock-based compensation and clinical trial accounting. Cash Equivalents The Company considers all highly liquid securities with original maturities of three months or less from the date of purchase to be cash equivalents, which generally consist of money market funds and corporate debt securities. Fair Value Measurements The Company measures cash equivalents at fair value on a recurring basis using the following hierarchy to prioritize valuation inputs, in accordance with applicable GAAP: Level 1 - Observable input such as quoted prices (unadjusted) in active markets for identical assets and liabilities that can be accessed at the measurement date; Level 2 - inputs other than quoted prices included within Level 1 that are observable, either directly or indirectly Level 3 - unobservable inputs To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3, if any. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The carrying amounts of the Company’s financial instruments, including Leases The Company determines if an arrangement is or contains a lease at inception. In determining whether an arrangement is a lease, the Company considers whether (1) explicitly or implicitly identified assets have been deployed in the arrangement and (2) the Company obtains substantially all of the economic benefits from the use of that underlying asset and directs how and for what purpose the asset is used during the term of the contract. ROU assets represent the Company’s right to use an underlying asset for the lease term, and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized based on the present value of lease payments over the lease term. When an implicit rate is not readily determinable, the Company uses its incremental borrowing rate based on the information available at commencement date for new leases or effective date for existing leases, in determining the present value of lease payments. Leases may contain initial periods of free rent and/or periodic escalations. When such items are included in a lease agreement, the Company records rent expense on a straight-line basis over the initial term of a lease. The difference between the rent payment and the straight-line rent expense is recorded as a deferred rent liability. The Company expenses any additional payments under its operating leases for taxes, insurance or other operating expenses as incurred Revenue Recognition The Company accounts for its contract revenues under Topic 606, Revenue from Contracts with Customers The Company’s contracts consist license, milestone and royalty payments primarily generated through agreements with strategic partners for the development and commercialization of the Company’s product candidates. The terms of the agreement typically include non-refundable upfront fees, payments based upon achievement of milestones and royalties on net product sales. The Company has both fixed and variable consideration. Non-refundable upfront fees are considered fixed, while milestone and royalty payments are identified as variable consideration. In determining the appropriate amount of revenue to be recognized as it fulfills its performance obligations under its agreements, the Company performs the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations based on estimated selling prices; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. Licenses of intellectual property: If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from non-refundable, up-front fees allocated to the license when the license is transferred to the customer, and the customer can use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Event-based or milestone payments: At the inception of each arrangement that includes event-based or milestone payments, the Company evaluates whether the events or milestones are considered probable of being achieved and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the value of the associated event-based or milestone payments is included in the transaction price. Event-based or milestone payments that are not within the control of the Company are not included in the transaction price until they become probable of being achieved. Royalties: For arrangements that include sales-based royalties and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (a) when the related sales occur, or (b) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue resulting from any of its licensing arrangements. Research and Development Research and development expense consists primarily of: (a) clinical trial costs, which include payments for work performed by contract research organizations (“CROs”), clinical trial sites, labs and other clinical service providers, and for drug packaging, storage and distribution; (b) drug manufacturing costs, which include costs for producing drug substance and drug product, and for stability and other testing; (c) personnel costs for related permanent and temporary employees; (d) other outside services and consulting costs; and (e) payments under license agreements. All research and development costs are expensed as they are incurred. Clinical Trial Accounting The Company records accruals for estimated clinical trial costs, which include payments for work performed by CROs and participating clinical trial sites. These costs are generally a significant component of research and development expense. Costs incurred for setting up clinical trial sites for participation in trials are generally non-refundable, and are expensed as incurred, with any refundable advances related to enrollment of the first patient recorded as prepayments and assessed for recoverability on a quarterly basis. Costs related to patient enrollment are accrued as patients progress through the clinical trial, including amortization of any first-patient prepayments. This amortization generally matches when the related services are rendered, however, these cost estimates may or may not match the actual costs incurred by the CROs or clinical trial sites, and if the Company has incomplete or inaccurate information, the clinical trial accruals may not be accurate. The difference between accrued expenses based on the Company’s estimates and actual expenses have not been significant to date. Warrants for Shares of Common Stock The Company accounts for warrants for shares of common stock as equity instruments in the accompanying balance sheets at their fair value on the date of issuance because such warrants are indexed to the Company’s common stock and no cash settlement is required except for (i) liquidation of the Company, or (ii) a change in control in which the common stockholders also receive cash. Stock-Based Compensation The Company grants options to purchase common stock to its employees, directors and consultants under its stock option plans. Under the Company’s Employee Stock Purchase Plan, eligible employees can also purchase shares of the Company’s common stock at 85% of the lower of the fair market value of the Company’s common stock at the beginning of a 12-month offering period or at the end of one of the two related six-month purchase periods. The Company values these share-based awards using the Black-Scholes option valuation model (the “Black-Scholes model”). The determination of fair value of share-based payment awards on the date of grant using the Black-Scholes model is affected by the Company’s stock price as well as assumptions regarding a number of subjective variables. These variables include, but are not limited to, the expected stock price volatility over the term of the awards and actual and projected employee stock option exercise behaviors. The Company accounts for forfeitures of share-based payment awards as they occur. Income Taxes The Company accounts for income taxes under the liability method. Under this method, deferred tax assets and liabilities are determined based on the differences between the tax basis of assets and liabilities and their basis for financial reporting. Deferred tax assets or liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which temporary differences are expected to be recovered or settled. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized. The Company’s policy is to recognize interest charges and penalties in other income, net in the statements of operations and comprehensive loss.

Loss per Common Share

Loss per Common Share	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Loss per Common Share	3. Loss per Common Share Basic loss per common share is calculated by dividing net loss by the weighted-average number of common shares outstanding for the period. Diluted net loss per common share is computed by dividing (a) net loss, less any anti-dilutive amounts recorded during the period, by (b) the weighted-average number of common shares outstanding for the period plus dilutive potential common shares as determined using the treasury stock method for options and warrants to purchase common stock. The following table sets forth the computation of basic and diluted loss per common share for the periods presented (in thousands, except per share amounts): Year Ended December 31, 2020 2019 Numerator: Net loss—basic and diluted $ (21,610 ) $ (23,330 ) Denominator: Weighted-average common shares outstanding—basic and diluted 14,093 8,712 Net loss per common share: Basic and Diluted $ (1.53 ) $ (2.68 ) The following table represents the potential common shares issuable pursuant to outstanding securities as of the related period end dates that were excluded from the computation of diluted loss per common share because their inclusion would have had an anti-dilutive effect (in thousands): As of December 31, 2020 2019 Warrants to purchase shares of common stock 21 22 Convertible preferred stock 1,025 1,971 Options to purchase shares of common stock 678 516 Outstanding securities not included in calculations 1,724 2,509

Financial Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Financial Instruments	4. Financial Instruments Financial Assets The following tables summarize the estimated fair value of the Company’s financial assets measured on a recurring basis as of the dates indicated (in thousands): Gross Gross Valuation Amortized Unrealized Unrealized Estimated Fair December 31, 2020 Input Level Cost Gains Losses Value Money market funds - classified as cash equivalents Level 1 $ 19,504 $ — $ — $ 19,504 Gross Gross Valuation Amortized Unrealized Unrealized Estimated Fair December 31, 2019 Input Level Cost Gains Losses Value Money market funds Level 1 $ 3,495 $ — $ — $ 3,495 U.S. Treasury securities Level 1 1,594 1 — 1,595 Repurchase agreements Level 2 5,000 — — 5,000 U.S. corporate debt obligations Level 2 5,155 — — 5,155 U.S. commercial paper Level 2 11,412 — — 11,412 Total available-for-sale securities 26,656 1 — 26,657 Less amounts classified as cash equivalents (10,293 ) — — (10,293 ) Amounts classified as marketable securities $ 16,363 $ 1 $ — $ 16,364 There were no available-for-sale securities in an unrealized loss position as of December 31, 2020 and 2019. There were no realized gains or losses on the available-for-sale securities in the years ended December 31, 2020 and 2019. There were no sales of available-for-sale debt securities in the years ended December 31, 2020 and 2019.

Other Accrued Liabilities

Other Accrued Liabilities	12 Months Ended
	Dec. 31, 2020
Payables And Accruals [Abstract]
Other Accrued Liabilities	5. Other Accrued Liabilities Other accrued liabilities as of December 31 were as follows (in thousands): 2020 2019 Accrued outside services $ 299 $ 690 Accrued professional services 624 220 Accrued interest — 57 Deferred revenue — 120 Other accruals 164 22 Total other accrued liabilities $ 1,087 $ 1,109

License Agreements

License Agreements	12 Months Ended
	Dec. 31, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
License Agreements	6. License Agreements Biogen Idec The first amended and restated collaboration agreement with Biogen Idec MA, Inc. (the “Biogen 1st ARCA”) amended and restated the collaboration agreement with Biogen (the “Biogen OCA”), to provide for the discovery, development and commercialization of small molecule BTK inhibitors. Under this agreement, the Company no longer has research obligations, but licenses granted to Biogen with respect to the research collaboration under the Biogen OCA (other than the licenses transferred to Takeda Oncology under the Takeda Agreement) remain in effect. In December 2018, the Company entered into a settlement agreement with Biogen whereas Biogen will no longer be obligated to pay future event-based payments or royalty payments to the Company. In December 2013, the Company entered into a second amended and restated collaboration agreement with Biogen, to provide the Company with an exclusive worldwide license to develop, manufacture and commercialize vecabrutinib Takeda In March 2011, Takeda Oncology purchased and exclusively licensed Biogen’s rights to a PDK1 inhibitor program and a pan-Raf inhibitor program which were both originally developed through a collaboration agreement between Sunesis and Biogen. In January 2014, the Company entered into an amended and restated license agreement with Takeda Oncology (the “Amended Takeda Agreement”), to provide the Company with an exclusive worldwide license to develop and commercialize preclinical inhibitors of PDK1. In December 2019, the Company partitioned the Amended Takeda Agreement into two separate agreements: (i) an amended and restated license agreement for PDK (the “PDK Agreement”), and (ii) an amended and restated license agreement for RAF (the “Millennium RAF Agreement”). Pursuant to the PDK Agreement, the Company may in the future be required to pay up to $9.2 million in pre-commercialization milestone payments depending on its development of PDK1 inhibitors and tiered royalty payments depending on related product sales, if any, beginning in the mid-single-digits and not to exceed the low-teens. DOT-1 In December 2019, Takeda Oncology assigned the Millennium RAF Agreement to DOT-1, a venture capital-funded biopharmaceutical company. The Company entered into a concurrent license agreement with DOT-1. Pursuant to this agreement, the Company received a $2.0 million upfront payment from DOT-1 to grant DOT-1 a worldwide, exclusive license of DAY101. The agreement also includes up to $57.0 million in pre-commercialization, event-based milestone payments and royalty payments to Sunesis on future sales of DAY101. The Company recognized the $2.0 million upfront payment as revenue upon inception of the contract as identified performance obligation has been satisfied. As of December 31, 2020, all future event-based payments and royalty payments are considered fully constrained variable considerations and therefore, no contract assets have been recorded and no revenue have been recognized Denovo In December 2019, the Company entered into the Denovo License Agreement, pursuant to which Sunesis licensed vosaroxin intellectual property to Denovo, received an upfront payment of $0.2 million, and is eligible to receive up to $57.0 million in regulatory and commercial milestones payments and double-digit royalty payments on future sales of vosaroxin. The Company recognized $0.1 million of the upfront payment as revenue in 2019 and the remaining $0.1 million during the first quarter of 2020 when the identified performance obligation was satisfied. As of December 31, 2020, all future event-based payments and royalty payments are considered fully constrained variable considerations and therefore, no contract assets have been recorded and no revenue have been recognized

Notes Payable

Notes Payable	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Notes Payable	7 . Notes Payable In April 2019, the Company entered into a term loan agreement with Silicon Valley Bank (the “SVB Loan Agreement”), pursuant to which the Company borrowed $5.5 million. In April 2020, the Company entered into a deferral agreement with Silicon Valley Bank (“SVB”), which extended the interest-only payment period through June 30, 2021 and deferred the maturity date of the borrowings to June 1, 2023. In July 2020, the Company repaid in full all outstanding indebtedness and terminated all commitments and obligations under the SVB Loan Agreement. The repayment to SVB was approximately $5.7 million, which satisfied all of the Company’s debt obligations, including a final interest payment equal to 4% of the original principal amount of the borrowing.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	8. Commitments and Contingencies From time to time, the Company may be involved in legal proceedings, as well as demands, claims and threatened litigation, which arise in the normal course of its business or otherwise. Following announcement of the merger agreement on November 29, 2020, nine lawsuits were filed by alleged stockholders of Sunesis challenging the merger. As of the date of the filing of this Form 10-K, the plaintiffs in all nine lawsuits have filed voluntary notices of dismissal. On January 8, 2021, a lawsuit was filed by a purported stockholder of Sunesis in connection with the proposed merger between Sunesis and Viracta. The lawsuit was brought as a putative class action and captioned Mooney v. Sunesis Pharmaceuticals, Inc., et al. Mooney Mooney Additional complaints were filed against Sunesis and the Sunesis board on January 14, 15, 16, 19, 21, and 29, 2021 (captioned Hajdini v. Sunesis Pharmaceuticals, Inc., et al. Blomquist v. Sunesis Pharmaceuticals, Inc., et al. Ciccotelli v. Sunesis Pharmaceuticals, Inc., et al. Zivan v. Sunesis Pharmaceuticals, Inc., et al. Rond v. Sunesis Pharmaceuticals, Inc., et al. Wheeler v. Sunesis Pharmaceuticals, Inc., et al. Kubicek v. Sunesis Pharmaceuticals, Inc., et al Sabina v. Sunesis Pharmaceuticals, Inc., et al. Ciccotelli Sabina Hajdini On February 12, 2021, Sunesis filed a Form 8-K to update and supplement the proxy statement/prospectus/information statement with additional disclosures relating to the Merger. Notices of voluntary dismissal have since been filed in all nine lawsuits. The ultimate outcome of any litigation is uncertain and unfavorable outcomes could have a negative impact on the Company’s results of operations and financial condition. Regardless of outcome, litigation can have an adverse impact on the Company because of the defense costs, diversion of management resources and other factors. Except as provided above, the Company is not currently involved in any material legal proceedings.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Stockholders' Equity	9. Stockholders’ Equity Underwritten Offerings In July 2020, the Company completed underwritten public offering of 5,999,999 shares of its common stock, including the full exercise of the underwriter’ option to purchase 782,608 shares of common stock to cover over-allotments, at a price to the public of $2.30 for each share of common stock. Gross proceeds from the sale were approximately $13.8 million and net proceeds were approximately $12.6 million. Preferred Stock The Company has 10,000,000 shares of authorized preferred stock available for issuance in one or more series. Upon issuance, the Company can determine the rights, preferences, privileges and restrictions thereof. These rights, preferences and privileges could include dividend rights, conversion rights, voting rights, terms of redemption, liquidation preferences, sinking fund terms and the number of shares constituting any series or the designation of such series, any or all of which may be greater than the rights of common stock. There were 10,248 and 19,714 shares of preferred stock outstanding as of December 31, 2020 2019, respectively. During the year ended December 31, 2020, the Company issued a total of 946,600 shares of its common stock upon conversion of 1,381 shares of its Series D Stock and 8,085 shares of Series E Stock. As of December 31, 2020, zero, 1,915, and 8,333 shares of Series D Stock, Series E Stock, and Series F Stock remain outstanding, respectively. The Series E Stock and Series F Stock are non-voting Series E and Series F Convertible Preferred Stock at a price of $500 and $600 per share, respectively. Each share of non-voting Series E Stock and Series F Stock is convertible into 100 shares of common stock, provided that conversion will be prohibited if, as a result, the holder and its affiliates would own more than 9.98% of the total number of shares of common stock then outstanding . In the event of the Company’s liquidation, dissolution, or winding up, holders of Series E and Series F Stock will receive a payment equal to $0.0001 per share of Series E and Series F Stock before any proceeds are distributed to the holders of Common Stock. Shares of Series E and Series F Stock will generally have no voting rights, except as required by law and except that the consent of holders of a majority of the outstanding Series E Stock will be required to amend the terms of the Series E and Series F Stock. Shares of the Series E and Series F Stock will not be entitled to receive any dividends, unless and until specifically declared by the Company’s board of directors, and will rank: • senior to all of the Company’s Common Stock; • senior to any class or series of the Company’s capital stock hereafter created specifically ranking by its terms junior to the Series E and Series F Stock; • on parity with any class or series of the Company’s capital stock hereafter created specifically ranking by its terms on parity with the Series E and Series F Stock; • junior to any class or series of the Company’s capital stock hereafter created specifically ranking by its terms senior to the Series E and Series F Stock; in each case, as to distributions of assets upon the Company’s liquidation, dissolution or winding up whether voluntarily or involuntarily. Common Stock Holders of common stock are entitled to one vote per share on all matters to be voted upon by the stockholders of the Company. Subject to the preferences that may be applicable to any outstanding shares of preferred stock, the holders of common stock are entitled to receive ratably such dividends, if any, as may be declared by the Board of Directors. Controlled Equity Offerings In August 2011, the Company entered into a Controlled Equity Offering SM During the years ended December 31, 2020 and 2019, the Company sold zero shares and less than 0.1 0.5 Aspire Common Stock Purchase Agreement In June 2018, the Company entered into a Common Stock Purchase Agreement (the “CSPA”) with Aspire Capital Fund, LLC (“Aspire”), pursuant to which the Company could issue and sell shares of its common stock having an aggregate gross sales price of up to $15.5 million. The CSPA with Aspire expired on June 25, 2020 and no shares were issued under the CSPA in 2019 and 2020 prior to its expiration. Equity Incentive Plans The Company grants options to purchase shares of its common stock primarily to: (i) new employees, of which 25% of the shares subject to such options become exercisable on the first anniversary of the vesting commencement date, and 1/48th of the shares subject to such options become exercisable each month over the remainder of the four-year vesting period, (ii) existing employees with various vesting schedules over three to four years, (iii) new non-employee members of the board of directors, of which 1/24th of the shares subject to such options become exercisable each month following the date of grant over a two-year vesting period, and (iv) continuing non-employee members of the board of directors, of which 1/12th of the shares subject to such options become exercisable each month following the date of grant over a one-year vesting period. On March 15, 2011, the Company’s Board of Directors adopted, and on June 3, 2011, the Company’s stockholders approved, the 2011 Equity Incentive Plan (the “2011 Plan”). The 2011 Plan is intended as the successor to and continuation of the Company’s 1998 Stock Plan, 2001 Stock Plan, 2005 Equity Incentive Award Plan and 2006 Employment Commencement Incentive Plan (collectively, the “Prior Plans”). No additional stock awards will be granted under the Prior Plans. The number of shares of common stock available for issuance under the 2011 Plan automatically increases on January 1st of each year for a period of 10 years commencing on January 1, 2012 by an amount equal to: (i) 4.0% of the Company’s outstanding shares of common stock on December 31st of the preceding calendar year, or (ii) a lesser amount determined by the Board of Directors. On January 1, 2020 and 2019, in accordance with the above, . During the year ended December 31, 2020, options to purchase 337,087 398,550 Employee Stock Purchase Plans On March 5, 2011, the Company’s Board of Directors adopted, and on June 3, 2011, the Company’s stockholders approved, the 2011 Employee Stock Purchase Plan (the “2011 ESPP”). The 2011 ESPP permits eligible employees to purchase common stock at a discount through payroll deductions during defined offering periods. Eligible employees can purchase shares of the Company’s common stock at 85% of the lower of the fair market value of the common stock at (i) the beginning of a 12-month offering period, or (ii) at the end of one of the two related 6-month purchase periods. No participant in the 2011 ESPP may be issued or transferred shares of common stock valued at more than $25,000 per calendar year. The number of shares of common stock available for issuance under the 2011 ESPP automatically increases on January 1st of each year for a period of 10 years commencing on January 1, 2012 by an amount equal to: (i) 1.0% of the Company’s outstanding shares of common stock on December 31st of the preceding calendar year, or (ii) a lesser amount determined by the Board of Directors. On January 1, 2020, in accordance with the above, the number of shares of common stock available for issuance under the 2011 ESPP was increased by 27,848 shares. A total of 22,413 Warrants Warrants to purchase shares of the Company’s common stock outstanding as of December 31, 2020 were as follows (in thousands, except per share amounts): Exercise Price Date Issued Shares Per Share Expiration March 2016 21 $ 32.45 March 2021 Total warrants outstanding and exercisable 21 Reserved Shares Shares of the Company’s common stock reserved for future issuance as of December 31, 2020 Shares Available Total for Future Outstanding Shares Grant Securities Reserved Warrants — 21 21 Convertible preferred stock — 1,025 1,025 Stock option plans 399 678 1,077 Employee stock purchase plan 32 — 32 Total reserved shares of common stock 431 1,724 2,155

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	10. Stock-Based Compensation Overview Employee stock-based compensation expense is calculated based on the grant-date fair value of awards ultimately expected to vest and recognized under the straight-line attribution method, assuming that all stock-based awards will vest. The following table summarizes stock-based compensation expense related to the Company’s stock-based awards for the periods indicated (in thousands): Year ended December 31, 2020 2019 Research and development $ 490 $ 513 General and administrative 530 816 Employee stock-based compensation expense 1,020 1,329 Non-employee stock-based compensation expense 304 420 Total stock-based compensation expense $ 1,324 $ 1,749 Fair Value of Awards The Company determines the fair value of stock-based awards on the grant date using the Black-Scholes model, which is impacted by the Company’s stock price, as well as assumptions regarding a number of subjective variables. The following table summarizes the weighted-average assumptions used as inputs to the Black-Scholes model, and resulting weighted-average and total estimated grant date fair values of employee stock options granted during the periods indicated: Year Ended December 31, 2020 2019 Employees Consultants Employees Consultants Assumptions: Expected term (years) 4.7 4.9 4.4 4.2 Expected volatility 117.6 % 118.1 % 108.9 % 114.2 % Risk-free interest rate 0.3 % 0.4 % 1.9 % 1.7 % Expected dividend yield 0.0 % 0.0 % 0.0 % 0.0 % Fair value: Weighted-average estimated grant date fair value per share $ 3.12 $ 3.36 $ 6.70 $ 5.60 Options granted (in thousands) 288 49 110 62 Total estimated grant date fair value (in thousands) $ 897 $ 166 $ 735 $ 292 The estimated fair value of stock options that vested in the years ended December 31, 2020 and 2019 was $ 1.2 Option Plan Activity The following table summarizes stock option activity for the Company’s stock option plans in the periods presented (in thousands, except per share amounts): Weighted Weighted Average Average Number Exercise Remaining Aggregate of Price Per Contractual Intrinsic Shares Share Term (Years) Value Outstanding as of December 31, 2019 516 $ 27.30 Options granted 337 $ 4.20 Options exercised — $ — Options forfeited or expired (175 ) $ 8.30 Outstanding as of December 31, 2020 678 $ 20.23 6.98 $ — Vested and expected to vest as of December 31, 2020 678 $ 20.23 6.98 $ — Exercisable as of December 31, 2020 508 $ 24.85 6.31 $ — The aggregate intrinsic value in the table above represents the total pre-tax intrinsic value (i.e., the difference between the Company’s closing stock price on the last trading day of the period and the exercise price, multiplied by the number of in-the-money options) that would have been received by option holders if they had exercised all their options on December 31, 2020. The intrinsic value of options exercised during each of the years ended December 31, 2020 and 2019 was zero. As the Company believes it is probable that no stock option related tax benefits will be realized, the Company does not record any net tax benefits related to exercised options. Total estimated unrecognized stock-based compensation cost related to unvested stock options was $ 0.7 2.1

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	11. Income Taxes Loss before the provision for income taxes consisted of the following (in thousands): Year Ended December 31, 2020 2019 U.S. operations $ (21,609 ) $ (23,330 ) Foreign operations — — Loss before provision for income taxes $ (21,609 ) $ (23,330 ) No provision for income taxes was recorded in the periods presented due to tax losses incurred in each period and the Company’s full valuation allowance position. The income tax provision differs from the amount computed by applying the statutory income tax rate of 21% to pre-tax loss as follows: Year Ended December 31, 2020 2019 Tax (benefit) at statutory federal rate 21.0 % 21.0 % State tax (benefit), net of federal benefit 7.5 7.1 Permanent differences (0.6 ) (0.6 ) Research and development credits 1.3 1.3 Change in valuation allowance (19.1 ) (20.9 ) Provision-to-return — — Expired NOLs, research and development credits, and other carryforwards (9.8 ) (6.9 ) Non-qualified stock option cancellations (0.3 ) (1.0 ) Effective tax rate — % — % Deferred income taxes reflect the net tax effects of loss and credit carry-forwards and temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of the Company’s deferred tax assets for federal and state income taxes are as follows (in thousands): December 31, 2020 2019 Deferred tax assets: Federal and state net operating loss carry-forwards $ 123,313 $ 119,015 Federal and state research credit carry-forwards 15,235 15,140 Capitalized research costs 5,772 6,081 Stock-based compensation 4,110 3,996 Lease liabilities 76 152 Property and equipment 74 77 Accrued liabilities 4 86 Gross deferred tax assets 148,584 144,547 Deferred tax liabilities: Right-of-use assets (76 ) (152 ) Gross deferred tax liabilities (76 ) (152 ) Net deferred tax assets 148,508 144,395 Valuation allowance (148,508 ) (144,395 ) Deferred tax assets, net of valuation allowance $ — $ — The Company’s unrecognized tax benefits relate to research and development tax credits claimed on the Company’s tax returns. The research and development tax credits have not been utilized, are fully offset by a valuation allowance, and currently have no tax expense impact and no related interest and penalties have been accrued. The Company does not anticipate the unrecognized tax benefits position will significantly change over the next twelve months. Due to the valuation allowance, no amount of unrecognized tax benefits would affect the effective tax rate if recognized. A reconciliation of the Company’s beginning and ending amount of unrecognized tax benefits is follows (in thousands): December 31, 2020 2019 Unrecognized tax benefits at beginning of period $ 1,847 $ 1,812 Increases related to current year tax positions 55 58 Decreases related to prior year tax positions (37 ) (23 ) Unrecognized tax benefits at the end of period $ 1,865 $ 1,847 The Company has recorded a full valuation allowance against its net deferred tax assets due to the uncertainty as to whether such assets will be realized. The valuation allowance increased by approximately $4.1 million in the year ended December 31, 2020 primarily due to the generation of current year net operating losses and research and development credits claimed. As of December 31, 2020, the Company had federal net operating loss carry-forwards of $ 475.8 The Company recognizes the financial statement effect of tax positions when it is more likely than not that the tax positions will be sustained upon examination by the appropriate taxing authorities. As of December 31, 2020 and 2019, the Company had unrecognized tax benefits of $1.9 million and $1.8 million, respectively. The Company files U.S. federal and California tax returns. The Company’s wholly owned subsidiary, Sunesis Europe Limited, currently is not required to file tax returns. To date, neither the Company nor any of its subsidiary have been audited by the Internal Revenue Service, any state income tax authority or tax authority in the related jurisdictions. Due to net operating loss carry-forwards, substantially all of the Company’s tax years remain open to tax examination.

Guarantees and Indemnification

Guarantees and Indemnification	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Guarantees and Indemnification	12. Guarantees and Indemnification As permitted under Delaware law and in accordance with the Company’s Bylaws, the Company indemnifies its officers and directors for certain events or occurrences, subject to certain limits, while the officer or director is or was serving at the Company’s request in such capacity. The indemnification agreements with the Company’s officers and directors terminate upon termination of their employment, but the termination does not affect claims for indemnification relating to events occurring prior to the effective date of termination. The maximum amount of potential future indemnification is unlimited; however, the Company’s officer and director insurance policy reduces the Company’s exposure and may enable the Company to recover a portion of any future amounts paid. The Company believes that the fair value of these indemnification agreements is minimal. In addition, in the ordinary course of business the Company enters into agreements, such as licensing agreements, clinical trial agreements and certain services agreements, containing standard indemnifications provisions. The Company believes that the likelihood of an adverse judgment related to such indemnification provisions is remote. Accordingly, the Company has not recorded any liabilities for any of these agreements as of December 31, 2020.

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Leases	13. Leases The Company’s operating lease obligations as of December 31, 2020 relate solely to the leasing of office space in a building at 395 Oyster Point Boulevard in South San Francisco, California, which is currently the Company’s headquarters. The lease was entered into in January 2014 and was amended several times since 2014. The lease was last amended in December 2017 to extend the expiration date to June 30, 2021, with an option to extend the lease for two additional years. The Company did not assume the option to extend the lease term for two additional years in its determination of the lease term as the exercise of the option was not reasonably certain when the lease was last amended in December 2017. The remaining lease term as of December 31, 2020 was six months. The cash paid for operating lease liability was $0.6 million for the year ended December 31, 2020. Maturity of lease liability is as follows (in thousands): Through December 31, Payments 2021 294 Total rental payments 294 Less imputed interest (21 ) Present value of lease liability $ 273 The Company recognizes rent expense on a straight-line basis. The Company recorded rent expense of $0.6 million for each of the year ended December 31, 2020 and 2019.

Restructuring Costs

Restructuring Costs	12 Months Ended
	Dec. 31, 2020
Restructuring And Related Activities [Abstract]
Restructuring Costs	14. Restructuring Costs In July 2020, the Company reduced its workforce by 30% to focus on development of its PDK1 inhibitor SNS-510 while evaluating its strategic alternatives with a goal to enhance stockholder value, including asset in-licensing, partnering, and mergers and acquisitions. As a result, during the three months ended September 30, 2020, the Company recognized and paid a one-time employee severance expenses of $0.2 million, which was recorded as operating expenses on the consolidated statement of operations and comprehensive loss. In December 2020, due to the entry into the Merger Agreement, Sunesis reduced its workforce by approximately 40% to preserve cash resources while completing the proposed Merger. As a result, during the three months ended December 31, 2020, the Company recognized one-time employee severance expenses of $1.3 million, which were included in accrued compensation on the consolidated balance sheet as of December 31, 2020, and noncash stock compensation expenses related to accelerated vesting of certain employee stock options of $0.1 million. The total expense of $1.4 million were recorded as operating expenses on the consolidated statement of operations and comprehensive loss with $0.9 million in research and development expenses and $0.5 million in general and administrative expenses.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2020
Subsequent Events [Abstract]
Subsequent Events	15. Subsequent Events On February 19, 2021, the Company sold its equity investment in Carmot Therapeutics, Inc. (“Carmot”) for net proceeds of approximately $0.7 million.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”).
Reverse Stock Split	Reverse Stock Split On September 2, 2020, the Company effected a one-for-ten reverse split of its outstanding common stock (the "Reverse Split"), as previously authorized and approved at the annual meeting of stockholders on June 16, 2020. As a result of the Reverse Split, every ten shares of common stock were combined into one share of common stock. The Reverse Split affected the shares of Company's common stock: (a) outstanding immediately prior to the effective time of the Reverse Split, (b) available for issuance under the Company's equity incentive plans, (c) issuable upon the exercise of outstanding stock options and warrants and (d) issuable upon conversion of the outstanding non-voting Series E and Series F Convertible Preferred Stock. All share and per-share data in the Company’s consolidated financial statements and notes thereto give retroactive effect to the Reverse Split for all periods presented.
Adopted Accounting Pronouncements	Adopted Accounting Pronouncements In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement Recent Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instruments Codification Improvements to Topic 326, Financial Instruments—Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments Financial Instruments—Credit Losses, Topic 326 Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842): Effective Dates Codification Improvements to Topic 326, Financial Instruments—Credit Losses, In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. In August 2020, the FASB issued ASU No. 2020-06, Debt – Debt with Conversion and Other options (Subtopic 470-20) and Derivative and Hedging – Contracts in Entity’s Own Equity (Subtopic 815-40).
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly owned subsidiary, Sunesis Europe Limited, a United Kingdom corporation. All intercompany balances and transactions have been eliminated in consolidation.
Segment Reporting	Segment Reporting Management has determined that the Company operates as a single reportable segment.
Significant Estimates and Judgments	Significant Estimates and Judgments The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the Company’s consolidated financial statements and accompanying notes thereto. Actual results could differ materially from these estimates. Estimates, assumptions and judgments made by management include those related to the valuation of marketable securities, equity and related instruments, revenue recognition, stock-based compensation and clinical trial accounting.
Cash Equivalents	Cash Equivalents The Company considers all highly liquid securities with original maturities of three months or less from the date of purchase to be cash equivalents, which generally consist of money market funds and corporate debt securities.
Fair Value Measurements	Fair Value Measurements The Company measures cash equivalents at fair value on a recurring basis using the following hierarchy to prioritize valuation inputs, in accordance with applicable GAAP: Level 1 - Observable input such as quoted prices (unadjusted) in active markets for identical assets and liabilities that can be accessed at the measurement date; Level 2 - inputs other than quoted prices included within Level 1 that are observable, either directly or indirectly Level 3 - unobservable inputs To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3, if any. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The carrying amounts of the Company’s financial instruments, including
Leases	Leases The Company determines if an arrangement is or contains a lease at inception. In determining whether an arrangement is a lease, the Company considers whether (1) explicitly or implicitly identified assets have been deployed in the arrangement and (2) the Company obtains substantially all of the economic benefits from the use of that underlying asset and directs how and for what purpose the asset is used during the term of the contract. ROU assets represent the Company’s right to use an underlying asset for the lease term, and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized based on the present value of lease payments over the lease term. When an implicit rate is not readily determinable, the Company uses its incremental borrowing rate based on the information available at commencement date for new leases or effective date for existing leases, in determining the present value of lease payments. Leases may contain initial periods of free rent and/or periodic escalations. When such items are included in a lease agreement, the Company records rent expense on a straight-line basis over the initial term of a lease. The difference between the rent payment and the straight-line rent expense is recorded as a deferred rent liability. The Company expenses any additional payments under its operating leases for taxes, insurance or other operating expenses as incurred
Revenue Recognition	Revenue Recognition The Company accounts for its contract revenues under Topic 606, Revenue from Contracts with Customers The Company’s contracts consist license, milestone and royalty payments primarily generated through agreements with strategic partners for the development and commercialization of the Company’s product candidates. The terms of the agreement typically include non-refundable upfront fees, payments based upon achievement of milestones and royalties on net product sales. The Company has both fixed and variable consideration. Non-refundable upfront fees are considered fixed, while milestone and royalty payments are identified as variable consideration. In determining the appropriate amount of revenue to be recognized as it fulfills its performance obligations under its agreements, the Company performs the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations based on estimated selling prices; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. Licenses of intellectual property: If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from non-refundable, up-front fees allocated to the license when the license is transferred to the customer, and the customer can use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Event-based or milestone payments: At the inception of each arrangement that includes event-based or milestone payments, the Company evaluates whether the events or milestones are considered probable of being achieved and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the value of the associated event-based or milestone payments is included in the transaction price. Event-based or milestone payments that are not within the control of the Company are not included in the transaction price until they become probable of being achieved. Royalties: For arrangements that include sales-based royalties and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (a) when the related sales occur, or (b) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue resulting from any of its licensing arrangements.
Research and Development	Research and Development Research and development expense consists primarily of: (a) clinical trial costs, which include payments for work performed by contract research organizations (“CROs”), clinical trial sites, labs and other clinical service providers, and for drug packaging, storage and distribution; (b) drug manufacturing costs, which include costs for producing drug substance and drug product, and for stability and other testing; (c) personnel costs for related permanent and temporary employees; (d) other outside services and consulting costs; and (e) payments under license agreements. All research and development costs are expensed as they are incurred.
Clinical Trial Accounting	Clinical Trial Accounting The Company records accruals for estimated clinical trial costs, which include payments for work performed by CROs and participating clinical trial sites. These costs are generally a significant component of research and development expense. Costs incurred for setting up clinical trial sites for participation in trials are generally non-refundable, and are expensed as incurred, with any refundable advances related to enrollment of the first patient recorded as prepayments and assessed for recoverability on a quarterly basis. Costs related to patient enrollment are accrued as patients progress through the clinical trial, including amortization of any first-patient prepayments. This amortization generally matches when the related services are rendered, however, these cost estimates may or may not match the actual costs incurred by the CROs or clinical trial sites, and if the Company has incomplete or inaccurate information, the clinical trial accruals may not be accurate. The difference between accrued expenses based on the Company’s estimates and actual expenses have not been significant to date.
Warrants for Shares of Common Stock	Warrants for Shares of Common Stock The Company accounts for warrants for shares of common stock as equity instruments in the accompanying balance sheets at their fair value on the date of issuance because such warrants are indexed to the Company’s common stock and no cash settlement is required except for (i) liquidation of the Company, or (ii) a change in control in which the common stockholders also receive cash.
Stock-Based Compensation	Stock-Based Compensation The Company grants options to purchase common stock to its employees, directors and consultants under its stock option plans. Under the Company’s Employee Stock Purchase Plan, eligible employees can also purchase shares of the Company’s common stock at 85% of the lower of the fair market value of the Company’s common stock at the beginning of a 12-month offering period or at the end of one of the two related six-month purchase periods. The Company values these share-based awards using the Black-Scholes option valuation model (the “Black-Scholes model”). The determination of fair value of share-based payment awards on the date of grant using the Black-Scholes model is affected by the Company’s stock price as well as assumptions regarding a number of subjective variables. These variables include, but are not limited to, the expected stock price volatility over the term of the awards and actual and projected employee stock option exercise behaviors. The Company accounts for forfeitures of share-based payment awards as they occur.
Income Taxes	Income Taxes The Company accounts for income taxes under the liability method. Under this method, deferred tax assets and liabilities are determined based on the differences between the tax basis of assets and liabilities and their basis for financial reporting. Deferred tax assets or liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which temporary differences are expected to be recovered or settled. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized. The Company’s policy is to recognize interest charges and penalties in other income, net in the statements of operations and comprehensive loss.

Loss per Common Share (Tables)

Loss per Common Share (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Computation of Basic and Diluted Loss per Common Share	The following table sets forth the computation of basic and diluted loss per common share for the periods presented (in thousands, except per share amounts): Year Ended December 31, 2020 2019 Numerator: Net loss—basic and diluted $ (21,610 ) $ (23,330 ) Denominator: Weighted-average common shares outstanding—basic and diluted 14,093 8,712 Net loss per common share: Basic and Diluted $ (1.53 ) $ (2.68 )
Schedule of Potential Common Shares Issuable Pursuant to Outstanding Securities Excluded from Computation of Diluted Loss per Common Share	The following table represents the potential common shares issuable pursuant to outstanding securities as of the related period end dates that were excluded from the computation of diluted loss per common share because their inclusion would have had an anti-dilutive effect (in thousands): As of December 31, 2020 2019 Warrants to purchase shares of common stock 21 22 Convertible preferred stock 1,025 1,971 Options to purchase shares of common stock 678 516 Outstanding securities not included in calculations 1,724 2,509

Financial Instruments (Tables)

Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value of Company's Financial Assets Measured on Recurring Basis	The following tables summarize the estimated fair value of the Company’s financial assets measured on a recurring basis as of the dates indicated (in thousands): Gross Gross Valuation Amortized Unrealized Unrealized Estimated Fair December 31, 2020 Input Level Cost Gains Losses Value Money market funds - classified as cash equivalents Level 1 $ 19,504 $ — $ — $ 19,504 Gross Gross Valuation Amortized Unrealized Unrealized Estimated Fair December 31, 2019 Input Level Cost Gains Losses Value Money market funds Level 1 $ 3,495 $ — $ — $ 3,495 U.S. Treasury securities Level 1 1,594 1 — 1,595 Repurchase agreements Level 2 5,000 — — 5,000 U.S. corporate debt obligations Level 2 5,155 — — 5,155 U.S. commercial paper Level 2 11,412 — — 11,412 Total available-for-sale securities 26,656 1 — 26,657 Less amounts classified as cash equivalents (10,293 ) — — (10,293 ) Amounts classified as marketable securities $ 16,363 $ 1 $ — $ 16,364

Other Accrued Liabilities (Tabl

Other Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Payables And Accruals [Abstract]
Summary of Other Accrued Liabilities	Other accrued liabilities as of December 31 were as follows (in thousands): 2020 2019 Accrued outside services $ 299 $ 690 Accrued professional services 624 220 Accrued interest — 57 Deferred revenue — 120 Other accruals 164 22 Total other accrued liabilities $ 1,087 $ 1,109

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Schedule of Warrants to Purchase Shares of Company's Common Stock	Warrants to purchase shares of the Company’s common stock outstanding as of December 31, 2020 were as follows (in thousands, except per share amounts): Exercise Price Date Issued Shares Per Share Expiration March 2016 21 $ 32.45 March 2021 Total warrants outstanding and exercisable 21
Shares of Common Stock Reserved for Future Issuance	Shares of the Company’s common stock reserved for future issuance as of December 31, 2020 Shares Available Total for Future Outstanding Shares Grant Securities Reserved Warrants — 21 21 Convertible preferred stock — 1,025 1,025 Stock option plans 399 678 1,077 Employee stock purchase plan 32 — 32 Total reserved shares of common stock 431 1,724 2,155

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock-Based Compensation Expense Related to Company's Stock-Based Awards	The following table summarizes stock-based compensation expense related to the Company’s stock-based awards for the periods indicated (in thousands): Year ended December 31, 2020 2019 Research and development $ 490 $ 513 General and administrative 530 816 Employee stock-based compensation expense 1,020 1,329 Non-employee stock-based compensation expense 304 420 Total stock-based compensation expense $ 1,324 $ 1,749
Summary of Weighted-Average and Total Estimated Grant Date Fair Values of Employee Stock Options Granted	The following table summarizes the weighted-average assumptions used as inputs to the Black-Scholes model, and resulting weighted-average and total estimated grant date fair values of employee stock options granted during the periods indicated: Year Ended December 31, 2020 2019 Employees Consultants Employees Consultants Assumptions: Expected term (years) 4.7 4.9 4.4 4.2 Expected volatility 117.6 % 118.1 % 108.9 % 114.2 % Risk-free interest rate 0.3 % 0.4 % 1.9 % 1.7 % Expected dividend yield 0.0 % 0.0 % 0.0 % 0.0 % Fair value: Weighted-average estimated grant date fair value per share $ 3.12 $ 3.36 $ 6.70 $ 5.60 Options granted (in thousands) 288 49 110 62 Total estimated grant date fair value (in thousands) $ 897 $ 166 $ 735 $ 292
Summary of Stock Option Activity for Company's Stock Option Plans	The following table summarizes stock option activity for the Company’s stock option plans in the periods presented (in thousands, except per share amounts): Weighted Weighted Average Average Number Exercise Remaining Aggregate of Price Per Contractual Intrinsic Shares Share Term (Years) Value Outstanding as of December 31, 2019 516 $ 27.30 Options granted 337 $ 4.20 Options exercised — $ — Options forfeited or expired (175 ) $ 8.30 Outstanding as of December 31, 2020 678 $ 20.23 6.98 $ — Vested and expected to vest as of December 31, 2020 678 $ 20.23 6.98 $ — Exercisable as of December 31, 2020 508 $ 24.85 6.31 $ —

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Loss before Provision for Income Taxes	Loss before the provision for income taxes consisted of the following (in thousands): Year Ended December 31, 2020 2019 U.S. operations $ (21,609 ) $ (23,330 ) Foreign operations — — Loss before provision for income taxes $ (21,609 ) $ (23,330 )
Income Tax Provision Amount Computed by Applying Statutory Income Tax Rate	The income tax provision differs from the amount computed by applying the statutory income tax rate of 21% to pre-tax loss as follows: Year Ended December 31, 2020 2019 Tax (benefit) at statutory federal rate 21.0 % 21.0 % State tax (benefit), net of federal benefit 7.5 7.1 Permanent differences (0.6 ) (0.6 ) Research and development credits 1.3 1.3 Change in valuation allowance (19.1 ) (20.9 ) Provision-to-return — — Expired NOLs, research and development credits, and other carryforwards (9.8 ) (6.9 ) Non-qualified stock option cancellations (0.3 ) (1.0 ) Effective tax rate — % — %
Significant Components of Deferred Tax Assets	Significant components of the Company’s deferred tax assets for federal and state income taxes are as follows (in thousands): December 31, 2020 2019 Deferred tax assets: Federal and state net operating loss carry-forwards $ 123,313 $ 119,015 Federal and state research credit carry-forwards 15,235 15,140 Capitalized research costs 5,772 6,081 Stock-based compensation 4,110 3,996 Lease liabilities 76 152 Property and equipment 74 77 Accrued liabilities 4 86 Gross deferred tax assets 148,584 144,547 Deferred tax liabilities: Right-of-use assets (76 ) (152 ) Gross deferred tax liabilities (76 ) (152 ) Net deferred tax assets 148,508 144,395 Valuation allowance (148,508 ) (144,395 ) Deferred tax assets, net of valuation allowance $ — $ —
Reconciliation of Unrecognized Tax Benefits	A reconciliation of the Company’s beginning and ending amount of unrecognized tax benefits is follows (in thousands): December 31, 2020 2019 Unrecognized tax benefits at beginning of period $ 1,847 $ 1,812 Increases related to current year tax positions 55 58 Decreases related to prior year tax positions (37 ) (23 ) Unrecognized tax benefits at the end of period $ 1,865 $ 1,847

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Maturity of Lease Liability	Maturity of lease liability is as follows (in thousands): Through December 31, Payments 2021 294 Total rental payments 294 Less imputed interest (21 ) Present value of lease liability $ 273

Company Overview - Additional I

Company Overview - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 18, 2020	Dec. 31, 2020	Jul. 31, 2020	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Percentage of reduction in workforce	40.00%	40.00%	30.00%
Severance costs related to reduction in workforce					$ 200
Cash and cash equivalents		$ 20,410		$ 20,410		$ 12,761
Accumulated deficit		$ 704,410		704,410		$ 682,800
Accrued Compensation [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Severance costs related to reduction in workforce	$ 1,300			1,300
Operating Expenses [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Severance costs related to reduction in workforce					$ 200
Noncash stock options compensation expenses	$ 100			$ 100

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Detail)	Sep. 02, 2020	Mar. 05, 2011	Dec. 31, 2020Segment
Significant Accounting Policies [Line Items]
Number of reportable segment			1
Common stock offering period			At the beginning of a 12-month offering period or at the end of one of the two related six-month purchase periods.
Employee Stock Purchase Plan [Member]
Significant Accounting Policies [Line Items]
Purchase price of a share as a percentage of fair market value		85.00%	85.00%
ASU 2018-13 [Member]
Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]			true
Change in Accounting Principle, Accounting Standards Update, Adoption Date			Mar. 31, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]			true
ASU 2016-13 [Member]
Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Early Adoption [true false]			true
ASU 2020-06 [Member]
Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Early Adoption [true false]			true
Common Stock [Member]
Significant Accounting Policies [Line Items]
Reverse stock split			one-for-ten
Conversion ratio	10

Loss per Common Share - Computa

Loss per Common Share - Computation of Basic and Diluted Loss per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Numerator:
Net loss	$ (21,610)	$ (23,330)
Denominator:
Weighted-average common shares outstanding—basic and diluted	14,093	8,712
Net loss per common share:
Basic and Diluted	$ (1.53)	$ (2.68)

Loss per Common Share - Schedul

Loss per Common Share - Schedule of Potential Common Shares Issuable Pursuant to Outstanding Securities Excluded from Computation of Diluted Loss per Common Share (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding securities not included in calculations	1,724	2,509
Warrants to purchase shares of common stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding securities not included in calculations	21	22
Options to purchase shares of common stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding securities not included in calculations	678	516
Convertible preferred stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding securities not included in calculations	1,025	1,971

Financial Instruments - Fair Va

Financial Instruments - Fair Value of Company's Financial Assets Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost		$ 26,656
Available-for-sale securities, Gross Unrealized Gains		1
Available-for-sale securities, Estimated Fair Value		26,657
Less amounts classified as cash equivalents, Amortized Cost		(10,293)
Less amounts classified as cash equivalents, Estimated Fair Value		(10,293)
Amounts classified as marketable securities, Amortized Cost		16,363
Amounts classified as marketable securities, Gross Unrealized Gains		1
Amounts classified as marketable securities, Estimated Fair Value		16,364
Level 1 [Member] | Money market funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost	$ 19,504	3,495
Available-for-sale securities, Estimated Fair Value	$ 19,504	3,495
Level 1 [Member] | U.S. Treasury securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost		1,594
Available-for-sale securities, Gross Unrealized Gains		1
Available-for-sale securities, Estimated Fair Value		1,595
Level 2 [Member] | Repurchase agreements [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost		5,000
Available-for-sale securities, Estimated Fair Value		5,000
Level 2 [Member] | U.S. corporate debt obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost		5,155
Available-for-sale securities, Estimated Fair Value		5,155
Level 2 [Member] | U.S. commercial paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost		11,412
Available-for-sale securities, Estimated Fair Value		$ 11,412

Financial Instruments - Additio

Financial Instruments - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Unrealized loss on available-for-sale securities	$ 0	$ 0
Sales of available-for-sale debt securities	0	0
Realized gains or losses on available-for-sale securities	$ 0	$ 0

Other Accrued Liabilities - Sum

Other Accrued Liabilities - Summary of Other Accrued Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Accrued outside services	$ 299	$ 690
Accrued professional services	624	220
Accrued interest		57
Deferred revenue		120
Other accruals	164	22
Total other accrued liabilities	$ 1,087	$ 1,109

License Agreements - Additional

License Agreements - Additional Information (Detail) - USD ($)	Feb. 10, 2021	Dec. 31, 2019	Mar. 31, 2020	Sep. 30, 2017	Dec. 31, 2020
Biogen [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Milestone payment				$ 2,500,000
Takeda License Agreements [Member] | License Agreement Terms [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Potential pre-commercialization milestone payments payable		$ 9,200,000
DOT-1 License Agreement [Member] | License Agreement Terms [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Potential pre-commercialization payments receivable		57,000,000
Contract assets					$ 0
Received recognized on variable considerations					0
Upfront payment received		2,000,000
Upfront payment recognized as revenue		2,000,000
DOT-1 License Agreement [Member] | License Agreement Terms [Member] | Subsequent Event [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Development milestone payment received	$ 3,000,000
Denovo License Agreement [Member] | License Vosaroxin [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Contract assets					0
Received recognized on variable considerations					$ 0
Upfront payment received		200,000
Upfront payment recognized as revenue		100,000	$ 100,000
Regulatory, commercial milestones payments and double-digit royalty payments, receivable		$ 57,000,000

Notes Payable - Additional Info

Notes Payable - Additional Information (Detail) - Silicon Valley Bank [Member] - USD ($) $ in Millions	1 Months Ended
	Jul. 31, 2020	Apr. 30, 2020	Apr. 30, 2019
Debt Instrument [Line Items]
Repayments of debt	$ 5.7
Final payment interest fee, percentage	4.00%
Term Loan Agreement [Member]
Debt Instrument [Line Items]
Borrowing amount			$ 5.5
SVB Deferral Agreement [Member]
Debt Instrument [Line Items]
Debt instrument, extended interest-only payments date		Jun. 30, 2021
Maturity date		Jun. 1, 2023

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2020Lawsuit
Commitments And Contingencies Disclosure [Abstract]
Number of lawsuits filed upon merger agreement	9
Lawsuit filing date	January 8, 2021

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail)	Jan. 01, 2020shares	Jan. 01, 2019shares	Mar. 05, 2011	Jul. 31, 2020USD ($)$ / sharesshares	Nov. 30, 2017USD ($)	Dec. 31, 2020USD ($)PurchasePeriod$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares	Jun. 30, 2018USD ($)	Dec. 31, 2017USD ($)
Stockholders Equity [Line Items]
Shares of common stock issued						18,108,000	11,139,000
Proceeds from issuance of common stock, net | $						$ 12,633,000	$ 32,022,000
Preferred stock, shares authorized						10,000,000	10,000,000
Preferred stock, shares outstanding						10,248	19,714
Common stock, voting rights						one vote per share
Options granted, Number of Shares						337,000
Shares Available for Future Grant						431,000
2011 Plan [Member]
Stockholders Equity [Line Items]
Common stock available for issuance automatic increase period						10 years
Common stock available for issuance automatic increase maximum number of shares						4.00%
Shares of common stock available for issuance	445,572	149,896
Options granted, Number of Shares						337,087
Shares Available for Future Grant						398,550
Stock Option Plans [Member]
Stockholders Equity [Line Items]
Shares Available for Future Grant						399,000
Stock Option Plans [Member] | New Employees [Member]
Stockholders Equity [Line Items]
Option exercisable on first anniversary of vesting commencement date, percent						25.00%
Portion of option exercisable for each month over vesting percent						2.083%
Stock option plans, vesting period						4 years
Vesting rights						New employees, of which 25% of the shares subject to such options become exercisable on the first anniversary of the vesting commencement date, and 1/48th of the shares subject to such options become exercisable each month over the remainder of the four-year vesting period
Stock Option Plans [Member] | Existing Employees [Member]
Stockholders Equity [Line Items]
Vesting rights						Existing employees with various vesting schedules over three to four years
Stock Option Plans [Member] | New Non-Employee Board Members [Member]
Stockholders Equity [Line Items]
Portion of option exercisable for each month over vesting percent						4.166%
Stock option plans, vesting period						2 years
Vesting rights						New non-employee members of the board of directors, of which 50% of the shares subject to such options become exercisable on each of the first and second anniversary of the vesting commencement date
Stock Option Plans [Member] | Continuing Non-Employee Board Members [Member]
Stockholders Equity [Line Items]
Portion of option exercisable for each month over vesting percent						8.333%
Stock option plans, vesting period						1 year
Vesting rights						Continuing non-employee members of the board of directors, of which 1/24th of the shares subject to such options become exercisable each month following the date of grant over a two-year vesting period
Minimum [Member] | Stock Option Plans [Member] | Existing Employees [Member]
Stockholders Equity [Line Items]
Stock option plans, vesting period						3 years
Maximum [Member] | Stock Option Plans [Member] | Existing Employees [Member]
Stockholders Equity [Line Items]
Stock option plans, vesting period						4 years
Common Stock [Member]
Stockholders Equity [Line Items]
Conversion of preferred stock to common stock, shares						946,600	1,195,000
Number of shares issued under employee stock purchase plan						22,000	13,000
Series D Convertible Preferred Stock [Member]
Stockholders Equity [Line Items]
Preferred stock, shares outstanding						0
Convertible preferred stock, shares converted						1,381
Series E Convertible Preferred Stock [Member]
Stockholders Equity [Line Items]
Price per common share | $ / shares						$ 500
Preferred stock, shares outstanding						1,915
Convertible preferred stock, shares converted						8,085
Shares issued upon conversion						100
Series F Convertible Preferred Stock [Member]
Stockholders Equity [Line Items]
Price per common share | $ / shares						$ 600
Preferred stock, shares outstanding						8,333
Shares issued upon conversion						100
Series E and Series F Convertible Preferred Stock [Member]
Stockholders Equity [Line Items]
Preferred stock, payment to stock holders in the event of liquidation, dissolution or winding up preference per share | $ / shares						$ 0.0001
Preferred stock, voting rights						Shares of Series E and Series F Stock will generally have no voting rights, except as required by law and except that the consent of holders of a majority of the outstanding Series E Stock will be required to amend the terms of the Series E and Series F Stock.
Series E and Series F Convertible Preferred Stock [Member] | Minimum [Member]
Stockholders Equity [Line Items]
Percentage of outstanding common stock						9.98%
Underwritten Offering [Member]
Stockholders Equity [Line Items]
Shares of common stock issued				5,999,999
Price per common share | $ / shares				$ 2.30
Proceeds from issuance of common stock, gross | $				$ 13,800,000
Proceeds from issuance of common stock, net | $				$ 12,600,000
Option To Purchase Shares Of Over-Allotments [Member]
Stockholders Equity [Line Items]
Shares of common stock issued				782,608
Controlled Equity Offering Facilities [Member]
Stockholders Equity [Line Items]
Proceeds from issuance of common stock, gross | $						$ 0	$ 500,000
Proceeds from issuance of common stock, net | $						$ 0	$ 500,000
Common stock sales agreement, date						2011-08
Controlled Equity Offering Facilities [Member] | Common Stock [Member]
Stockholders Equity [Line Items]
Price per common share | $ / shares						$ 0	$ 11.90
Common stock, shares sold						0
Controlled Equity Offering Facilities [Member] | Common Stock [Member] | Maximum [Member]
Stockholders Equity [Line Items]
Common stock, shares sold							100,000
Additional Controlled Equity Offerings Facilities [Member]
Stockholders Equity [Line Items]
Common stock sales agreement further amended, date						2017-11
Increase in aggregate controlled equity offering agreement as per amendment | $					$ 45,000,000
Issuance of common stock through equity facilities commission percentage, maximum					3.00%
CSPA [Member] | Registration Rights Agreement [Member] | Aspire [Member]
Stockholders Equity [Line Items]
Common stock, shares sold						0	0
Date of termination						Jun. 25, 2020
CSPA [Member] | Maximum [Member] | Aspire [Member]
Stockholders Equity [Line Items]
Issuance of common stock, offering value | $								$ 15,500,000
Employee Stock Purchase Plan [Member]
Stockholders Equity [Line Items]
Common stock available for issuance automatic increase period						10 years
Common stock available for issuance automatic increase maximum number of shares						1.00%
Shares of common stock available for issuance	27,848
Shares Available for Future Grant						32,234
Purchase price of a share as a percentage of fair market value			85.00%			85.00%
Duration of offering period						12 months
Number of purchase periods in each offering period | PurchasePeriod						2
Duration of each purchase period						6 months
Share of common stock value | $									$ 25,000
Number of shares issued under employee stock purchase plan						22,413	13,332

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Warrants to Purchase Shares of Company's Common Stock (Detail) shares in Thousands	12 Months Ended
	Dec. 31, 2020$ / sharesshares
Class of Warrant or Right [Line Items]
Total warrants outstanding and exercisable, shares	21
March 2016 [Member]
Class of Warrant or Right [Line Items]
Total warrants outstanding and exercisable, shares	21
Warrants, Exercise Price Per Share | $ / shares	$ 32.45
Warrants Expiration Date	2021-03

Stockholders' Equity - Shares o

Stockholders' Equity - Shares of Common Stock Reserved for Future Issuance (Detail)	Dec. 31, 2020shares
Class of Stock [Line Items]
Shares Available for Future Grant	431,000
Outstanding Securities	1,724,000
Total Shares Reserved	2,155,000
Warrants [Member]
Class of Stock [Line Items]
Outstanding Securities	21,000
Total Shares Reserved	21,000
Stock Option Plans [Member]
Class of Stock [Line Items]
Shares Available for Future Grant	399,000
Outstanding Securities	678,000
Total Shares Reserved	1,077,000
Employee Stock Purchase Plan [Member]
Class of Stock [Line Items]
Shares Available for Future Grant	32,234
Total Shares Reserved	32,000
Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Outstanding Securities	1,025,000
Total Shares Reserved	1,025,000

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock-Based Compensation Expense Related to Company's Stock-Based Awards (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	$ 1,324	$ 1,749
Employee stock-based compensation expense [Member]
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	1,020	1,329
Non-employee stock-based compensation expense [Member]
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	304	420
Research and development [Member]
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	490	513
General and administrative [Member]
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	$ 530	$ 816

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Weighted-Average and Total Estimated Grant Date Fair Values of Employee Stock Options Granted (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Assumptions:
Expected dividend yield	0.00%
Fair value:
Options granted (in thousands)	337
Stock Option Plans [Member] | Employees [Member]
Assumptions:
Expected term (years)	4 years 8 months 12 days	4 years 4 months 24 days
Expected volatility	117.60%	108.90%
Risk-free interest rate	0.30%	1.90%
Expected dividend yield	0.00%	0.00%
Fair value:
Weighted-average estimated grant date fair value per share	$ 3.12	$ 6.70
Options granted (in thousands)	288	110
Total estimated grant date fair value (in thousands)	$ 897	$ 735
Stock Option Plans [Member] | Consultants [Member]
Assumptions:
Expected term (years)	4 years 10 months 24 days	4 years 2 months 12 days
Expected volatility	118.10%	114.20%
Risk-free interest rate	0.40%	1.70%
Expected dividend yield	0.00%	0.00%
Fair value:
Weighted-average estimated grant date fair value per share	$ 3.36	$ 5.60
Options granted (in thousands)	49	62
Total estimated grant date fair value (in thousands)	$ 166	$ 292

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Estimated fair value of stock options, vested	$ 1,200,000	$ 1,600,000
Payment of cash dividends	$ 0
Dividend yield ratio	0.00%
Intrinsic value of options exercised	$ 0	$ 0
Tax benefits related to stock option exercised	0
Unrecognized stock-based compensation cost related to unvested stock options	$ 700,000
Weighted average term of unrecognized stock-based compensation expense	2 years 1 month 6 days

Stock-Based Compensation - Su_3

Stock-Based Compensation - Summary of Stock Option Activity for Company's Stock Option Plans (Detail) shares in Thousands	12 Months Ended
	Dec. 31, 2020$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding, Beginning Balance, Number of Shares | shares	516
Options granted, Number of Shares | shares	337
Options forfeited or expired, Number of Shares | shares	(175)
Outstanding, Ending Balance, Number of Shares | shares	678
Vested and expected to vest as of December 31, 2020, Number of Shares | shares	678
Exercisable as of December 31, 2020, Number of Shares | shares	508
Outstanding, Beginning Balance, Weighted Average Exercise Price Per Share | $ / shares	$ 27.30
Options granted, Weighted Average Exercise Price Per Share | $ / shares	4.20
Options forfeited or expired, Weighted Average Exercise Price Per Share | $ / shares	8.30
Outstanding, Ending Balance, Weighted Average Exercise Price Per Share | $ / shares	20.23
Vested and expected to vest as of December 31, 2020, Weighted Average Exercise Price Per Share | $ / shares	20.23
Exercisable as of December 31, 2020, Weighted Average Exercise Price Per Share | $ / shares	$ 24.85
Outstanding, Weighted Average Remaining Contractual Term (Years)	6 years 11 months 23 days
Vested and expected to vest as of December 31, 2020, Weighted Average Remaining Contractual Term (Years)	6 years 11 months 23 days
Exercisable as of December 31, 2020, Weighted Average Remaining Contractual Term (Years)	6 years 3 months 21 days

Income Taxes - Loss before Prov

Income Taxes - Loss before Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
U.S. operations	$ (21,609)	$ (23,330)
Loss before provision for income taxes	$ (21,609)	$ (23,330)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Line Items]
Income tax provision	$ 0	$ 0
Statutory income tax rate	21.00%	21.00%
Unrecognized tax benefits that would have tax impact	$ 0
Unrecognized tax benefits, interest and penalties accrued	0
Unrecognized tax benefits position will significantly change over the next twelve months	0
Net valuation allowance, increased (decreased)	4,100,000
Unrecognized tax benefit	1,865,000	$ 1,847,000	$ 1,812,000
Domestic tax authority [Member]
Income Taxes [Line Items]
Net operating loss carry-forwards	475,800,000
Research and development tax credit carry-forwards	$ 9,700,000
Net operating loss carry-forwards expiration	2021
State and local jurisdiction [Member]
Income Taxes [Line Items]
Net operating loss carry-forwards	$ 335,000,000
Research and development tax credit carry-forwards	$ 8,900,000
Net operating loss carry-forwards expiration	2028

Income Taxes - Income Tax Provi

Income Taxes - Income Tax Provision Amount Computed by Applying Statutory Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Tax (benefit) at statutory federal rate	21.00%	21.00%
State tax (benefit), net of federal benefit	7.50%	7.10%
Permanent differences	(0.60%)	(0.60%)
Research and development credits	1.30%	1.30%
Change in valuation allowance	(19.10%)	(20.90%)
Expired NOLs, research and development credits, and other carryforwards	(9.80%)	(6.90%)
Non-qualified stock option cancellations	(0.30%)	(1.00%)

Income Taxes - Significant Comp

Income Taxes - Significant Components of Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Federal and state net operating loss carry-forwards	$ 123,313	$ 119,015
Federal and state research credit carry-forwards	15,235	15,140
Capitalized research costs	5,772	6,081
Stock-based compensation	4,110	3,996
Lease liabilities	76	152
Property and equipment	74	77
Accrued liabilities	4	86
Gross deferred tax assets	148,584	144,547
Deferred tax liabilities:
Right-of-use assets	(76)	(152)
Gross deferred tax liabilities	(76)	(152)
Net deferred tax assets	148,508	144,395
Valuation allowance	$ (148,508)	$ (144,395)

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Unrecognized tax benefits at beginning of period	$ 1,847	$ 1,812
Increases related to current year tax positions	55	58
Decreases related to prior year tax positions	(37)	(23)
Unrecognized tax benefits at the end of period	$ 1,865	$ 1,847

Guarantees and Indemnification

Guarantees and Indemnification - Additional Information (Detail)	Dec. 31, 2020USD ($)
Guarantees [Abstract]
Liabilities incurred in indemnification agreements	$ 0

Leases - Additional Information

Leases - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Line Items]
Cash paid for operating lease liability	$ 0.6
Rent expense	$ 0.6	$ 0.6
Original Operating Lease [Member]
Leases [Line Items]
Operating lease agreement, original date	2014-01
Fifth Amended Operating Lease [Member]
Leases [Line Items]
Lease expiration date	Jun. 30, 2021
Operating lease agreement, date of amendment	2017-12
Operating lease, property description	The lease was last amended in December 2017 to extend the expiration date to June 30, 2021, with an option to extend the lease for two additional years. The Company did not assume the option to extend the lease term for two additional years in its determination of the lease term as the exercise of the option was not reasonably certain when the lease was last amended in December 2017.
Lessee, operating lease, existence of option to extend [true false]	true
Option to extend the lease	option to extend the lease for two additional years.
Operating lease, renewal term	2 years
Operating lease, remaining term	6 months

Leases - Schedule of Maturity o

Leases - Schedule of Maturity of Lease Liability (Detail) $ in Thousands	Dec. 31, 2020USD ($)
Leases [Abstract]
2021	$ 294
Total rental payments	294
Less imputed interest	(21)
Present value of lease liability	$ 273

Restructuring Costs - Additiona

Restructuring Costs - Additional Information (Details) - USD ($) $ in Millions	Dec. 18, 2020	Dec. 31, 2020	Jul. 31, 2020	Dec. 31, 2020	Sep. 30, 2020
Restructuring Cost And Reserve [Line Items]
Percentage of reduction in workforce	40.00%	40.00%	30.00%
Severance costs related to reduction in workforce					$ 0.2
Accrued Compensation [Member]
Restructuring Cost And Reserve [Line Items]
Severance costs related to reduction in workforce	$ 1.3			$ 1.3
Operating Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Severance costs related to reduction in workforce					$ 0.2
Noncash stock options compensation expenses	$ 0.1			0.1
Restructuring expense				1.4
Research and development [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring expense				0.9
General and administrative [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring expense				$ 0.5

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) $ in Millions	Feb. 19, 2021USD ($)
Carmot Therapeutics, Inc. [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Net proceeds from sale of equity investment	$ 0.7