Viracta Therapeutics (VIRX) 10-Q 12 Aug 21 2021 Q2 Quarterly report Financial data

Cover Page

Cover Page - shares	6 Months Ended
	Jun. 30, 2021	Aug. 02, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Entity Registrant Name	VIRACTA THERAPEUTICS, INC.
Entity Central Index Key	0001061027
Entity Current Reporting Status	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		37,226,233
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	false
Entity File Number	000-51531
Entity Tax Identification Number	94-3295878
Entity Address, Address Line One	2533 S. Coast Hwy. 101, Suite 210
Entity Address, City or Town	Cardiff
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92007
City Area Code	858
Local Phone Number	400-8470
Document Quarterly Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
Entity Incorporation, State or Country Code	DE
Trading Symbol	VIRX
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Security Exchange Name	NASDAQ

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($)	Jun. 30, 2021	Dec. 31, 2020
Current Assets:
Cash and cash equivalents	$ 122,721,000	$ 47,089,000
Prepaid expenses	2,421,000	110,000
Total current assets	125,142,000	47,199,000
Property and equipment, net	41,000	44,000
Operating lease right-of-use asset	816,000	986,000
Other assets	2,680,000	76,000
Total assets	128,679,000	48,305,000
Current Liabilities:
Accounts payable	2,566,000	1,557,000
Accrued expenses	3,196,000	3,362,000
Operating lease liability	358,000	334,000
Current portion of long-term debt, net	833,000	1,031,000
Total current liabilities	6,953,000	6,284,000
Long-term debt, net	4,155,000	4,155,000
Operating lease liabilities, less current portion	474,000	658,000
Preferred stock warrant liability	0	106,000
Commitments and contingencies
Stockholders' equity (deficit):
Convertible preferred stock, $0.0001 par value; 10,000,000 shares authorized as of June 30, 2021; 10,248 shares issued and outstanding as of June 30, 2021	5,452,000	0
Common stock, $0.0001 par value; 400,000,000 shares authorized; 37,140,817 and 905,987 shares issued and outstanding at June 30, 2021 and December 31, 2020, respectively	4,000	1,000
Additional paid-in capital	250,957,000	4,714,000
Accumulated deficit	(139,316,000)	(50,915,000)
Total stockholders' equity (deficit)	117,097,000	(46,200,000)
Total liabilities and stockholders' equity (deficit)	128,679,000	48,305,000
Series A-1 Convertible Preferred Stock [Member]
Current Liabilities:
Convertible Preferred Stock	0	2,968,000
Series B Convertible Preferred Stock [Member]
Current Liabilities:
Convertible Preferred Stock	0	15,484,000
Series C Convertible Preferred Stock [Member]
Current Liabilities:
Convertible Preferred Stock	0	9,392,000
Series D Convertible Preferred Stock [Member]
Current Liabilities:
Convertible Preferred Stock		16,589,000
Series E Convertible Preferred Stock [Member]
Current Liabilities:
Convertible Preferred Stock	$ 0	$ 38,869,000

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Preferred stock, par value	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	10,248
Preferred stock, shares outstanding	10,248
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	37,140,817	905,987
Common stock, shares outstanding	37,140,817	905,987
Series A-1 Convertible Preferred Stock [Member]
Convertible Preferred Shares, Par Value Per Share		$ 0.0001
Convertible Preferred Shares, Authorized		4,819,012
Convertible Preferred Shares, Issued		4,819,012
Convertible Preferred Shares, Outstanding		4,819,012
Convertible Preferred Shares, Redemption Value		$ 13,720,612
Series B Convertible Preferred Stock [Member]
Convertible Preferred Shares, Par Value Per Share		$ 0.0001
Convertible Preferred Shares, Authorized		2,788,249
Convertible Preferred Shares, Issued		2,788,249
Convertible Preferred Shares, Outstanding		2,788,249
Convertible Preferred Shares, Redemption Value		$ 16,811,782
Series C Convertible Preferred Stock [Member]
Convertible Preferred Shares, Par Value Per Share		$ 0.0001
Convertible Preferred Shares, Authorized		1,587,722
Convertible Preferred Shares, Issued		1,587,722
Convertible Preferred Shares, Outstanding		1,587,722
Convertible Preferred Shares, Redemption Value		$ 10,695,494
Series D Convertible Preferred Stock [Member]
Convertible Preferred Shares, Par Value Per Share		$ 0.0001
Convertible Preferred Shares, Authorized		2,240,916
Convertible Preferred Shares, Issued		2,224,329
Convertible Preferred Shares, Outstanding		2,224,329
Convertible Preferred Shares, Redemption Value		$ 16,774,988
Series E Convertible Preferred Stock [Member]
Convertible Preferred Shares, Par Value Per Share		$ 0.0001
Convertible Preferred Shares, Authorized		7,472,730
Convertible Preferred Shares, Issued		7,392,240
Convertible Preferred Shares, Outstanding		7,392,240
Convertible Preferred Shares, Redemption Value		$ 39,999,997

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Operating expenses:
Research and development	$ 5,446	$ 3,361	$ 9,470	$ 6,807
Acquired in-process research and development	0	0	84,478	0
General and administrative	3,871	879	7,711	1,890
Total operating expenses	9,317	4,240	101,659	8,697
Gain on Royalty Purchase Agreement	0	0	13,500	0
Loss from operations	(9,317)	(4,240)	(88,159)	(8,697)
Other income (expense)
Gain on forgiveness of PPP Loan	257	0	257	0
Interest income	12	4	18	44
Interest expense	(122)		(227)
Other expense	0	0	(290)	0
Total other income (expense)	147	4	(242)	44
Net loss and comprehensive loss	$ (9,170)	$ (4,236)	$ (88,401)	$ (8,653)
Net loss per share of common stock, basic and diluted	$ (0.25)	$ (15.52)	$ (3.37)	$ (32.13)
Weighted-average shares used to compute basic and diluted net loss per share	37,221,407	273,056	26,255,992	269,325

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Series A-1 Convertible Preferred Stock [Member]	Series B Convertible Preferred Stock [Member]	Series C Convertible Preferred Stock [Member]	Series D Convertible Preferred Stock [Member]	Series E Convertible Preferred Stock [Member]	Shares issuable upon conversion of preferred stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]
Beginning Balance at Dec. 31, 2019	$ (28,383)	$ 2,968	$ 15,484	$ 9,392	$ 16,589	$ 0	$ 0	$ 0	$ 3,515	$ (31,898)
Beginning Balance, shares at Dec. 31, 2019		4,819,000	2,788,000	1,588,000	2,224,000	0	0	72,000
Vesting of early exercise of employee stock options	1								1
Vesting of early exercise of employee stock options. shares								1,000
Stock-based compensation expense	86								86
Net loss	(4,417)									(4,417)
Ending Balance at Mar. 31, 2020	(32,713)	$ 2,968	$ 15,484	$ 9,392	$ 16,589	$ 0	$ 0	$ 0	3,602	(36,315)
Ending Balance, shares at Mar. 31, 2020		4,819,000	2,788,000	1,588,000	2,224,000	0	0	73,000
Beginning Balance at Dec. 31, 2019	(28,383)	$ 2,968	$ 15,484	$ 9,392	$ 16,589	$ 0	$ 0	$ 0	3,515	(31,898)
Beginning Balance, shares at Dec. 31, 2019		4,819,000	2,788,000	1,588,000	2,224,000	0	0	72,000
Net loss	(8,653)
Ending Balance at Jun. 30, 2020	(36,869)	$ 2,968	$ 15,484	$ 9,392	$ 16,589	$ 0	$ 0	$ 0	3,682	(40,551)
Ending Balance, shares at Jun. 30, 2020		4,819,000	2,788,000	1,588,000	2,224,000	0	0	85,000
Beginning Balance at Mar. 31, 2020	(32,713)	$ 2,968	$ 15,484	$ 9,392	$ 16,589	$ 0	$ 0	$ 0	3,602	(36,315)
Beginning Balance, shares at Mar. 31, 2020		4,819,000	2,788,000	1,588,000	2,224,000	0	0	73,000
Exercise of warrants and stock options to purchase common stock	10								10
Exercise of warrants and stock options to purchase common stock, shares								11,000
Vesting of early exercise of employee stock options	1								1
Vesting of early exercise of employee stock options. shares								1,000
Stock-based compensation expense	69								69
Net loss	(4,236)									(4,236)
Ending Balance at Jun. 30, 2020	(36,869)	$ 2,968	$ 15,484	$ 9,392	$ 16,589	$ 0	$ 0	$ 0	3,682	(40,551)
Ending Balance, shares at Jun. 30, 2020		4,819,000	2,788,000	1,588,000	2,224,000	0	0	85,000
Beginning Balance at Dec. 31, 2020	(46,200)	$ 2,968	$ 15,484	$ 9,392	$ 16,589	$ 38,869	$ 0	$ 1	4,714	(50,915)
Beginning Balance, shares at Dec. 31, 2020		4,819,000	2,788,000	1,588,000	2,224,000	7,392,000	0	906,000
Exercise of warrants and stock options to purchase common stock	81								81
Exercise of warrants and stock options to purchase common stock, shares								132,000
Vesting of early exercise of employee stock options	1								1
Vesting of early exercise of employee stock options. shares								1,000
Issuance of common stock net of issuance costs	62,317							$ 1	62,316
Issuance of common stock net of issuance costs, shares								12,012,000
Issuance of common stock to fomer stockholders of Sunesis upon Merger	97,982								97,982
Issuance of common stock to fomer stockholders of Sunesis upon Merger, shares								5,173,000
Conversion of convertible preferred stock into common stock upon Merger	83,302	$ (2,968)	$ (15,484)	$ (9,392)	$ (16,589)	$ (38,869)		$ 2	83,300
Conversion of convertible preferred stock into common stock upon Merger, shares		(4,819,000)	(2,788,000)	(1,588,000)	(2,224,000)	(7,392,000)		18,812,000
Issuance of convertible preferred stock to former stockholders of Sunesis upon Merger	5,452						$ 5,452
Issuance of convertible preferred stock to former stockholders of Sunesis upon Merger, shares							10,000
Reclassification of preferred stock warrant liability to equity	396								396
Stock-based compensation expense	644								644
Net loss	(79,231)									(79,231)
Ending Balance at Mar. 31, 2021	124,744	$ 0	$ 0	$ 0	$ 0	$ 0	$ 5,452	$ 4	249,434	(130,146)
Ending Balance, shares at Mar. 31, 2021		0	0	0	0	0	10,000	37,036,000
Beginning Balance at Dec. 31, 2020	$ (46,200)	$ 2,968	$ 15,484	$ 9,392	$ 16,589	$ 38,869	$ 0	$ 1	4,714	(50,915)
Beginning Balance, shares at Dec. 31, 2020		4,819,000	2,788,000	1,588,000	2,224,000	7,392,000	0	906,000
Exercise of warrants and stock options to purchase common stock, shares	169,000
Net loss	$ (88,401)
Ending Balance at Jun. 30, 2021	117,097	$ 0	$ 0	$ 0	$ 0	$ 0	$ 5,452	$ 4	250,957	(139,316)
Ending Balance, shares at Jun. 30, 2021		0	0	0	0	0	10,000	37,141,000
Beginning Balance at Mar. 31, 2021	124,744	$ 0	$ 0	$ 0	$ 0	$ 0	$ 5,452	$ 4	249,434	(130,146)
Beginning Balance, shares at Mar. 31, 2021		0	0	0	0	0	10,000	37,036,000
Exercise of warrants and stock options to purchase common stock	136								136
Exercise of warrants and stock options to purchase common stock, shares								104,000
Vesting of early exercise of employee stock options	1								1
Vesting of early exercise of employee stock options. shares								1,000
Stock-based compensation expense	1,386								1,386
Net loss	(9,170)									(9,170)
Ending Balance at Jun. 30, 2021	$ 117,097	$ 0	$ 0	$ 0	$ 0	$ 0	$ 5,452	$ 4	$ 250,957	$ (139,316)
Ending Balance, shares at Jun. 30, 2021		0	0	0	0	0	10,000	37,141,000

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Operating activities
Net loss	$ (88,401)	$ (8,653)
Adjustments to reconcile net loss to net cash used in operating activities:
Gain on forgiveness of PPP Loan	(257)	0
Acquired in-process research and development	84,478	0
Share-based compensation expense	2,030	155
Depreciation and amortization	67	4
Change in fair value of preferred stock warrant liability	290	0
Change in operating assets and liabilities:
Prepaid expenses and other assets	(1,747)	(30)
Other assets	601	(8)
Accounts payable	587	961
Accrued liabilities	(1,699)	313
Lease liabilities, net	9	0
Net cash used in operating activities	(4,042)	(7,258)
Investing activities
Purchase of property and equipment	(5)	(50)
Cash acquired in connection with the Merger	17,143	0
Net cash provided by (used in) investing activities	17,138	(50)
Financing activities
Proceeds from debt, net of issuance costs	0	254
Issuance of common stock, net of issuance costs	62,319	0
Exercise of warrants and stock options to purchase common stock	217	10
Net cash provided by financing activities	62,536	264
Net increase (decrease) in cash and cash equivalents	75,632	(7,044)
Cash and cash equivalents at beginning of period	47,089	18,218
Cash and cash equivalents at end of period	122,721	11,174
Supplemental disclosure of cash flow information
Interest paid	142	0
Noncash financing activities
Operating lease right-of-use assets obtained in exchange for operating lease liabilities	0	667
Warrant liability reclassification to equity	396	0
Issuance of convertible preferred stock upon merger	5,452	0
Conversion of convertible preferred stock into common stock upon Merger	83,302	0
Issuance of common stock upon Merger	$ 97,982	$ 0

Organization and Basis of Prese

Organization and Basis of Presentation	6 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	1. Organization and Basis of Presentation Viracta Therapeutics, Inc. (“Viracta,” the “Company,” or the “combined company”), formerly known as Sunesis Pharmaceuticals, Inc., was incorporated in the state of Delaware in February 1998 and is based in San Diego, California. Viracta is a precision oncology company, focused on the development of new medicines targeting virus-associated malignancies. The Company is currently conducting multiple Phase 2 clinical trials for its combination product candidate as a potential therapy for the treatment of relapsed/refractory Epstein-Barr virus-positive (“EBV + ”) lymphoma. Merger Transaction between Private Viracta Therapeutics, Inc. and Sunesis Pharmaceuticals, Inc. and Name Change On November 29, 2020, the Company, then operating as Sunesis Pharmaceuticals, Inc., entered into an agreement and plan of merger and reorganization (the “Merger Agreement”) with privately-held Viracta Therapeutics, Inc. (“Private Viracta”) and Sol Merger Sub, Inc., a wholly-owned subsidiary of the Company (“Merger Sub”). On February 24, 2021, transactions contemplated by the Merger Agreement were completed, and Merger Sub merged into Private Viracta, with Private Viracta as surviving the merger as a wholly owned subsidiary of the Company (the "Merger") . Sunesis changed its name to Viracta Therapeutics, Inc. On February 25, 2021, the combined company’s common stock began trading on The Nasdaq Global Select Market under the ticker symbol “VIRX”. Except as otherwise indicated, references herein to “Viracta,” the “Company,” or the “combined company”, refer to Viracta Therapeutics, Inc. on a post-Merger basis, and the term “Private Viracta” refers to the business of privately-held Viracta Therapeutics, Inc., prior to the completion of the Merger. References to “Sunesis” refer to Sunesis Pharmaceuticals, Inc. prior to completion of the Merger. Pursuant to the terms of the Merger Agreement, each outstanding share of Private Viracta common stock outstanding immediately prior to the closing of the Merger was converted into approximately 0.1119 shares of Company common stock (the “Exchange Ratio”), after taking into account the Reverse Stock Split, as defined below. Immediately prior to the closing of the Merger, all shares of Private Viracta preferred stock then outstanding were exchanged into shares of common stock of Private Viracta. In addition, all outstanding options exercisable for common stock of Private Viracta and warrants exercisable for capital stock of Private Viracta became options and warrants exercisable for the same number of shares of common stock of the Company multiplied by the Exchange Ratio at an exercise price equal to the pre-Merger price divided by the Exchange Ratio. Immediately following the Merger, stockholders of Private Viracta owned approximately 86 % of the outstanding common stock of the combined company. This transaction was accounted for as a reverse asset acquisition in accordance with generally accepted accounting principles in the United States of America (“GAAP”), as Viracta was considered to be acquiring Sunesis and the Merger was accounted for as an asset acquisition, even though Sunesis was the legal acquirer and the issuer of the common stock in the Merger. This determination was primarily based on the facts that, immediately following the Merger: (i) Private Viracta’s stockholders owned a substantial majority of the voting rights in the combined company, (ii) Private Viracta designated a majority of the members of the initial board of directors of the combined company, and (iii) Private Viracta’s senior management holds all key positions in the senior management of the combined company. As a result, as of the closing date of the Merger, the net assets of Sunesis were recorded at their acquisition-date relative fair values in the accompanying condensed consolidated financial statements of the Company and the reported operating results prior to the Merger are those of Private Viracta. To determine the accounting for this transaction under GAAP, a company must assess whether an integrated set of assets and activities should be accounted for as an acquisition of a business or an asset acquisition. The guidance required an initial screen test to determine if substantially all of the fair value of the gross assets acquired was concentrated in a single asset or group of similar assets. The initial screen test was not met as there was no single asset or group of similar assets for Sunesis that represented a significant majority in this acquisition. However, at the time of the closing of the Merger, Sunesis did not have processes or an organized workforce that significantly contributed to its ability to create outputs, and substantially all of its fair value was concentrated in cash, working capital, and in-process research and development (“IPR&D”). As such, the acquisition was treated as an asset acquisition. Concurrent with the execution of the Merger Agreement, Private Viracta entered into an agreement for the sale of common stock in a private placement, which was completed immediately prior to the close of the Merger and resulted in gross proceeds of approximately $ 65.0 million. In connection with the closing of the Merger and the concurrent private placement of common stock, the holders of the Company’s preferred stock waived their right to exchange their shares into any class of the Company’s stock other than common stock. On February 24, 2021, in connection with, and prior to the completion of, the Merger, the Company effected a 3.5-for-one reverse stock split of its then outstanding common stock (the “Reverse Stock Split”). The par value and the authorized shares of the common stock were not adjusted as a result of the Reverse Stock Split. Unless otherwise noted herein, references to share and per-share amounts give retroactive effect to the Reverse Stock Split and the Exchange Ratio which was effected upon the Merger. Liquidity and Risks As of June 30, 2021, the Company has devoted substantially all of its efforts to product development and has not realized product sales revenues from its planned principal operations. The Company has a limited operating history, and the sales and income potential of the Company’s business and market are unproven. The Company has experienced net losses since its inception and, as of June 30, 2021, had an accumulated deficit of $ 139.3 million. The Company expects to continue to incur net losses for at least the next several years. A successful transition to attaining profitable operations is dependent upon achieving a level of revenues adequate to support the Company’s cost structure. If the Company is unable to generate revenues adequate to support its cost structure, the Company will need to raise additional equity through the issuance of its common stock, through other equity or debt financings or through collaborations or partnerships with other companies. As of June 30, 2021, the Company had cash and cash equivalents of approximately $ 122.7 million and working capital of $ 118.2 million. In February 2021, as disclosed above, Private Viracta completed the sale of common stock in a private placement resulting in gross proceeds of approximately $ 65.0 million. Additionally, the Company received approximately $ 17.1 million in cash and cash equivalents in the Merger previously discussed. Finally, in March 2021, the Company received $ 13.5 million in upfront proceeds related to the Royalty Purchase Agreement with XOMA (US) LLC (see Note 4). Based on the Company’s current financial position and business plan, management believes that its existing cash and cash equivalents will be sufficient to fund the Company’s planned operations for at least twelve months from the issuance date of these financial statements. The COVID-19 pandemic has caused significant business disruption around the globe. The extent of the impact of COVID-19 on the Company’s operational and financial performance will depend on certain developments, including the duration and spread of the pandemic and the impact on the Company’s clinical trials, employees, and vendors. At this point, the degree to which COVID-19 may impact the Company’s financial condition or results of operations is uncertain. A prolonged pandemic could have a material and adverse impact on financial results and business operations of the Company, including the timing and ability of the Company to complete certain clinical trials and other efforts required to advance the development of its product candidates and raise additional capital.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation and Principles of Consolidation The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries and have been prepared in accordance with GAAP and follow the requirements of the U.S. Securities and Exchange Commission (“SEC”) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by GAAP can be condensed or omitted. In management’s opinion, the unaudited interim financial statements have been prepared on the same basis as the audited financial statements and include all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of the Company’s financial position and its results of operations and its cash flows for the periods presented. These statements do not include all disclosures required by GAAP and should be read in conjunction with the Company’s financial statements and accompanying notes for the year ended December 31, 2020 , which are contained in the Company’s Current Report on Form 8-K/A filed with the SEC on March 23, 2021. The results for interim periods are not necessarily indicative of the results expected for the full fiscal year or any other interim period. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Actual results could differ materially from those estimates. Concentrations of Credit Risk Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash and cash equivalents. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company has not experienced any losses in such accounts and believes it is not exposed to significant risk on its cash and cash equivalents. Significant Accounting Policies On January 1, 2018, the Company adopted the provisions of ASC 610-20, Gain or Loss From Derecognition of Non-financial Assets (“ASC 610-20”). In accordance with ASC 610-20, the Company recognizes any gains when the Company transfers control of a property and when it is probable that the Company will collect substantially all of the related consideration. The Company had no transactions since the adoption except for on March 22, 2021, the Company entered into a Royalty Purchase Agreement with XOMA (US) LLC (“XOMA”), in which XOMA purchased the potential future milestones and royalties associated with existing licenses relating to two clinical-stage product candidates, DAY101 and vosaroxin, which were obtained in the Merger. The Company received an upfront payment of $ 13.5 million and may receive up to $ 20.0 million in a pre-commercialization, event-based milestone. There have been no other material changes in the Company’s accounting policies from those disclosed in the audited financial statements and related notes thereto as of and for the year ended December 31, 2020, which are contained in the Company’s Current Report on Form 8-K/A filed with the SEC on March 23, 2021. Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity from the date of purchase of three months or less to be cash equivalents. Cash and cash equivalents include cash in readily available check and money market accounts. Clinical Trial and Contracts Accruals Clinical trial costs include payments to sites participating in clinical trials and to outside contract research organizations that assist in developing, monitoring and administering the clinical trials. Measurement of clinical trial expenses and the related accrual recorded in any given period requires judgment as invoices or other notification of actual costs may not exist as of the date of the financial statements, making it necessary to estimate the efforts completed to date and the related expense. The period over which services are performed, the level of services performed as of a given date, and the cost of such services are often subjective determinations. The Company’s principal vendors operate within terms of contracts which establish program costs and estimated timelines. The status of the Company’s programs is assessed in relation to the scope of work outlined in the contracts, and the related amount of expense is recognized accordingly. Estimates are adjusted to actual costs as they become known and subsequent changes to estimates have not historically resulted in a material change to the accruals. Research and Development Expenses Research and development costs are expensed as incurred. These costs consist primarily of salaries and other personnel-related expenses, including share-based compensation; facility-related expenses; and services performed by clinical research organizations, research institutions, and other outside service providers. The Company recorded the estimated costs of research and development activities based upon the estimated amount of services provided but not yet invoiced and include these costs in accrued expenses in the balance sheet and within research and development expense in the statement of operations and comprehensive loss. As actual costs become known, the Company will adjust its accrued expenses and related research and development expenses. Share-Based Compensation Share-based compensation expense for stock option grants and restricted stock units (“RSUs”) under the Company’s equity plans are recorded at the estimated fair value of the award as of the grant date and recognized as expense on a straight-line basis over the requisite service period of the stock-based award, and forfeitures are recognized as they occur. The estimate of fair value for share-based compensation for stock options requires management to make estimates and judgments about, among other things, employee exercise behavior and volatility of the Company’s common stock. The judgments directly affect the amount of compensation expense that will be recognized. Segment Reporting Operating segments are identified as components of an enterprise about which separate discrete financial information is used in making decisions regarding resource allocation and assessing performance. To date, the Company has viewed its operations and managed its business as one segment operating in the United States. All long-lived assets were located in the United States at June 30, 2021 . Fair Value Measurements The accounting guidance defines fair value, establishes a consistent framework for measuring fair value and expands disclosure for each major asset and liability category measured at fair value on either a recurring or non-recurring basis. Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market- based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the accounting guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows: Level 1: Observable inputs such as quoted prices in active markets. Level 2: Inputs, other than the quoted prices in active markets that are observable either directly or indirectly. Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. The carrying amounts of the Company’s cash and cash equivalents, prepaid expenses, accounts payable and accrued liabilities approximate fair values for these financial instruments due to their short maturities. The preferred stock warrant liability, a level 3 fair value measurement, was $ 0 as of June 30, 2021 , due to the reclassification to equity, and $ 106,000 as of December 31, 2020. The Company had no assets or liabilities measured at fair value on a recurring basis as of June 30, 2021 . The Company had no assets or liabilities measured at fair value on a recurring basis as of December 31, 2020, other than the preferred stock warrant liability. Preferred stock warrant liability The assumptions used in the Black-Scholes option pricing model to determine the fair value of the preferred stock warrant liability were as follows: February 24, 2021 Expected volatility 90.2 % Risk-free interest rate 1.38 % Expected dividend yield 0 % Expected term 9.3 years Fair value per share of preferred stock $ 17.15 The following table provides a reconciliation of the preferred stock warrant liability measured at fair value using Level 3 significant unobservable inputs (in thousands): Preferred Stock Balance at December 31, 2020 $ 106 Change in fair value of preferred stock warrant liability 290 Reclassification to equity ( 396 ) Balance at June 30, 2021 $ — Net Loss Per Share Basic loss per common share is computed by dividing net loss by the weighted average number of common shares and warrants to purchase common stock for nominal consideration outstanding during the period. Diluted loss per common share is computed by dividing net loss by the weighted average number of common shares outstanding, plus the impact of common shares, if dilutive, resulting from the exercise of outstanding common stock equivalents. The following securities are excluded from the calculation of weighted average dilutive common shares because their inclusion would have been anti-dilutive: June 30, 2021 2020 Shares issuable upon conversion of preferred stock 292,799 11,419,329 Common stock options and RSUs outstanding 4,384,919 1,567,851 Warrants to purchase common stock 23,100 — Total excluded securities 4,700,818 12,987,180 Recent Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instruments , which will require a reporting entity to use a new forward-looking impairment model for most financial assets that generally will result in the earlier recognition of allowances for losses. For available-for-sale debt securities with unrealized losses, credit losses will be recognized as allowances rather than as reductions in amortized cost. Entities will apply the guidance as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is adopted. In April 2019, the FASB issued ASU 2019-04, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments , to increase stakeholders’ awareness of the amendments and to expedite improvements to the Codification. In May 2019, the FASB issued ASU 2019-05, Financial Instruments—Credit Losses, Topic 326 , providing an option to irrevocably elect the fair value option for certain financial assets previously measured at amortized cost basis. These ASUs do not change the core principle of the guidance in ASU 2016-13. Instead these amendments are intended to clarify and improve operability of certain topics. In November 2019, FASB issued ASU 2019-10, Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842): Effective Dates and ASU 2019-11, Codification Improvements to Topic 326, Financial Instruments—Credit Losses , which defers the effective dates of the new credit losses standard for all entities except SEC filers that are not smaller reporting companies to fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. The standard and other related subsequently issued ASUs will be effective for the Company for annual periods beginning after December 15, 2022, with early adoption permitted. The Company is currently evaluating the impact that the adoption of the standard and other related subsequently issued ASUs will have on its financial statements and accompanying footnotes. 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) . The amendments in this ASU reduce the number of accounting models for convertible debt instruments and convertible preferred stock, as well as amend the guidance for the derivatives scope exception for contracts in an entity’s own equity to reduce form-over-substance-based accounting conclusion. In addition, this ASU improves and amends the related earnings per share guidance. The amendments in this ASU are effective for the Company on January 1, 2024, including interim periods within those fiscal years. Early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2020, including interim periods within those fiscal years. Adoption is either a modified retrospective method or a fully retrospective method of transition. The Company early adopted ASU 2020-06 on January 1, 2021, electing the modified retrospective transition method that allows for a cumulative-effect adjustment in the period of adoption. The adoption of ASU 2020-06 did not have a material impact on the Company’s financial statements.

Financial Statement Details

Financial Statement Details	6 Months Ended
	Jun. 30, 2021
Financial Statement Details [Abstract]
Financial Statement Details	3. Financial Statement Details Accrued expenses consist of the following (in thousands): June 30, December 31, Accrued payroll and benefits $ 1,001 $ 1,501 Accrued clinical trial and contract expenses 1,331 1,095 Accrued professional services and expenses 342 716 Other accrued expenses 522 50 Total accrued expenses $ 3,196 $ 3,362

XOMA Transaction

XOMA Transaction	6 Months Ended
	Jun. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
XOMA Transaction	4. XOMA Transaction On March 22, 2021, the Company entered into a Royalty Purchase Agreement with XOMA (US) LLC (“XOMA”), in which XOMA purchased the potential future milestones and royalties associated with existing licenses relating to two clinical-stage product candidates, DAY101 and vosaroxin, which were obtained in the Merger (the “XOMA Transaction”). The Company received an upfront payment of $ 13.5 million and may receive up to $ 20.0 million in a pre-commercialization, event-based milestone. The upfront payment is nonrefundable, there are no clawback provisions, and the Company has no significant involvement or obligations going forward related to potential future milestones and royalties. The Company has recognized no income from the pre-commercialization, event-based milestone to date. In December 2019, Sunesis entered into a license agreement with DOT Therapeutics-1, LLC (“DOT-1”) to grant DOT-1 a worldwide, exclusive license of DAY101. The DOT-1 license agreement includes up to $ 57.0 million in potential pre-commercialization, event-based milestone payments and royalty payments on future sales of DAY101, when and if approved and commercialized, $ 3.0 million of which was received by Sunesis prior to the XOMA Transaction. Also in December 2019, Sunesis entered into an agreement to license vosaroxin to Denovo Biopharma LLC, which includes up to $ 57.0 million in potential regulatory and commercial milestones, and double-digit royalties on future sales of vosaroxin, when and if approved and commercialized. The potential milestone and royalty payments related to DAY101 and vosaroxin were sold in the XOMA Transaction.

Debt

Debt	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Debt	5. Debt SVB Loan Agreement On July 30, 2020, Private Viracta and Silicon Valley Bank (the “Lender”) entered into a loan and security agreement (the “SVB Loan Agreement”), providing for up to $ 15.0 million in four tranches. Upon entering into the SVB Loan Agreement, Private Viracta borrowed $ 5.0 million. Under the terms of the SVB Loan Agreement, the Company may, subject to the achievement of certain milestones, borrow from the Lender up to an additional $ 10.0 million until January 31, 2022. The loan will be due on the scheduled maturity date of July 1, 2024 (the “Maturity Date”). In accordance with the original terms of the SVB Loan Agreement, repayment of the loan was interest only through July 31, 2021, and in February 2021, upon completion of the private placement of common stock, the interest only period was extended through January 31, 2022. This period of interest only will be followed by 30 equal monthly payments of principal plus accrued interest commencing on February 1, 2022. The per annum interest rate for any outstanding loan is the lesser of (i) 10 %, or (ii) the greater of (A) 3.5 % above the prime rate or (B) 6.75%. The interest rate as of June 30, 2021 was 6.75 % per annum. In addition, a final payment of 7.0 % of the amount of the loan drawn will be due on the earlier of the Maturity Date, acceleration of the loan, or prepayment of the loan. The final payment is being accrued through interest expense using the effective interest method. If the Company elects to prepay the loan, a prepayment fee equal to 1 % or 2 % of the then outstanding principal balance will also be due, depending upon when the prepayment occurs. The Company is subject to customary affirmative and restrictive covenants under the SVB Loan Agreement. The Company’s obligations under the SVB Loan Agreement are secured by a first priority security interest in substantially all of its current and future assets, other than our intellectual property. The Company has also agreed not to encumber its intellectual property assets, except as permitted by the SVB Loan Agreement. The SVB Loan Agreement also contains customary indemnification obligations and customary events of default, including, among other things, the Company’s failure to fulfill certain obligations under the SVB Loan Agreement and the occurrence of a material adverse change in the Company’s business, operations, or condition (financial or otherwise), a material impairment of the prospect of repayment of any portion of the loan, or a material impairment in the perfection or priority of Lender’s lien in the collateral or in the value of such collateral. In the event of default by the Company under the SVB Loan Agreement, the Lender would be entitled to exercise their remedies thereunder, including the right to accelerate the debt, upon which the Company may be required to repay all amounts then outstanding under the SVB Loan Agreement. As of June 30, 2021, the Company was in compliance with all financial covenants under the SVB Loan Agreement and there had been no material adverse change. The following table summarizes future minimum payments under the term loan facility as of June 30, 2021 (in thousands): Year Ending December 31, 2021 $ 172 2022 2,123 2023 2,154 2024 1,543 Total future minimum payments 5,992 Less: interest payments ( 1,004 ) Principal amount of long-term debt 4,988 Current portion of long-term debt ( 833 ) Long-term debt, net $ 4,155 The debt issuance cost and common stock warrants issued are being accounted for as a debt discount. The debt discount is being amortized as interest expense over the term of the loan using the effective interest method. The carrying value of the debt approximates the fair value (Level 2) as of June 30, 2021. Paycheck Protection Program Loan On April 24, 2020, Viracta received loan proceeds of $ 253,700 from First Republic Bank, as lender, pursuant to the Payment Protection Program (“PPP”) of the CARES Act (the “PPP Loan”). The maturity date of the PPP Loan was April 23, 2022 , with a per annum interest rate of 1.0 %. The PPP Loan was evidenced by a promissory note dated April 23, 2020, which contained customary events of default relating to, among other things, payment defaults and breaches of representations and warranties. The PPP Loan could have been prepaid by the Company at any time prior to maturity with no prepayment penalties. All or a portion of the PPP Loan was potentially eligible for forgiveness by the U.S. Small Business Administration ("SBA") upon the Company’s application and upon documentation of expenditures in accordance with the SBA requirements. Under the CARES Act and PPP Flexibility Act, loan forgiveness was available for the sum of documented payroll costs, covered mortgage interest, covered rent payments and covered utilities during the 24-week period beginning on the date of loan disbursement. In the event the PPP Loan, or any portion thereof, was forgiven pursuant to the PPP, the amount forgiven would be applied to outstanding principal and would include accrued interest. The Company used all proceeds from the PPP Loan to retain employees, maintain payroll and make lease and utility payments, and sought forgiveness in accordance with the program in late 2020. In June 2021, the Company received notification from the SBA that the Company's Forgiveness Application of the PPP Loan and accrued interest, totaling $ 257,000 , was approved in full and the Company had no further obligations related to the PPP Loan. Accordingly, the Company recorded a gain on the forgiveness of the PPP Loan in the period ending June 30, 2021.

Merger

Merger	6 Months Ended
	Jun. 30, 2021
Business Combinations [Abstract]
Merger	6. Merger The Merger, which closed on February 24, 2021, was accounted for as a reverse asset acquisition pursuant to Topic 805, Business Combinations , as substantially all of its fair value was concentrated in cash, working capital, and IPR&D. As the IPR&D assets had no alternative future use, the fair value attributable to these assets was recorded as acquired IPR&D in the Company’s condensed consolidated statements of operations for the six months ended June 30, 2021. The estimated fair value of total consideration given was $ 103.4 million based on 5,173,772 shares of Sunesis common stock and 10,248 shares of Sunesis convertible preferred stock (or 292,799 Sunesis common shares on an as-converted basis) outstanding immediately prior to the merger date. The number of outstanding common stock and preferred stock on an as-converted basis was multiplied by the Sunesis closing common stock price of $ 18.62 on the date of the merger, plus transaction costs of approximately $ 1.6 million, to determine the estimated fair value of total consideration. The allocation of the purchase price is as follows (in thousands): Net assets acquired (1) $ 18,956 Acquired IPR&D (2) 84,478 Purchase price $ 103,434 (1) Net assets acquired (in thousands): Cash and cash equivalents $ 17,143 Prepaid expenses and other assets 3,768 Accounts payable and accrued liabilities ( 1,955 ) Net assets acquired $ 18,956 (2) Represents the research and development projects of Sunesis which were in-process, but not yet completed. Current accounting standards require that the fair value of IPR&D projects acquired in an asset acquisition with no alternative future use be allocated a portion of the consideration transferred and charged to expense on the acquisition date. The acquired IPR&D assets did not have outputs or employees.

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2021
Stockholders' Equity Note [Abstract]
Stockholders' Equity	7. Stockholders’ Equity Common Stock The total number of shares of common stock of Viracta outstanding as of June 30, 2021 and December 31, 2020 was 37,140,817 and 905,987 , respectively. Concurrent Financing On February 24 2021, immediately prior to the closing of the Merger, the Company completed the February 2021 private placement offering of an aggregate of 12,012,369 shares of common stock for gross proceeds of $ 65.0 million and incurred fees and other offering costs of approximately $ 2.7 million. Sales Agreement On May 28, 2021, the Company entered into an Open Market Sale Agreement SM (the “Sale Agreement”) with Jefferies LLC (the “Sales Agent”), under which the Company may offer and sell up to $ 50,000,000 of shares (the “Shares”) of its common stock, par value $ 0.0001 per share (“Common Stock”), from time to time through the Sales Agent. The sales and issuances, if any, of the Shares by the Company under the Sale Agreement will be pursuant to the Company’s registration statement on Form S-3 (the “Registration Statement”), filed with the SEC on May 28, 2021 and declared effective by the SEC on June 4, 2021. Sales, if any, of the Shares pursuant to the Sale Agreement may be made in negotiated transactions or transactions that are deemed to be “at the market offerings” as defined in Rule 415(a)(4) promulgated under the Securities Act of 1933, as amended, including sales made directly on The Nasdaq Stock Market, or sales made into any other existing trading market for the Common Stock. The Sales Agent is not required to sell any specific amount of securities, but will act as the Company’s sales agent using commercially reasonable efforts to sell the Shares from time to time, consistent with its normal trading and sales practices, applicable state and federal laws, rules and regulations and the rules of The Nasdaq Stock Market, based upon instructions from the Company (including any price, time or size limits or other customary parameters or conditions the Company may impose). As of June 30, 2021, the Company has incurred legal and accounting costs of $ 0.1 million related to the Sales Agreement. As of June 30, 2021, no shares had been issued pursuant to the Sales Agreement. Convertible Preferred Stock In connection with the Merger, all of the outstanding shares of Private Viracta’s convertible preferred stock were converted into 18,811,552 shares of the Company’s common stock. As of December 31, 2020, Private Viracta’s convertible preferred stock was classified as temporary equity on the accompanying condensed consolidated balance sheets in accordance with authoritative guidance for the classification and measurement of potentially redeemable securities whose redemption is based upon certain change in control events outside of Private Viracta’s control, including liquidations, sale or transfer of control of Private Viracta. Private Viracta did not adjust the carrying values of the convertible preferred stock to the liquidation preferences of such shares because the occurrence of any such change of control event was not deemed probable. With the Merger, the Company obtained 10,000,000 shares of authorized preferred stock available for future issuance in one or more series. Upon issuance, the Company can determine the rights, preferences, privileges and restrictions thereof. These rights, preference 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 shares of this preferred stock outstanding as of June 30, 2021 , of which 1,915 shares were Series E Stock and 8,333 shares were Series F Stock. The Series E Stock and Series F Stock are non-voting Series E and Series F Convertible Preferred Stock at a stated price of $ 500 and $ 600 per share, respectively. Each share of non-voting Series E Stock and Series F Stock is convertible at a conversion ratio equal to the stated price divided by the conversion price, which is $ 17.50 per share and $ 21.00 per share, respectively, 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 this 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; and  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. Warrants Concurrent with the issuance of convertible promissory notes in 2018, the Company issued to the note investors warrants to purchase 250,323 shares of Viracta Common Stock (the “Common Warrants”). The Common Warrants’ exercise price is $ 0.09 per share. Unless previously exercised, the Common Warrants will expire on the seven-year anniversary of the date of issuance. As of June 30, 2021 , 118,982 shares of Viracta Common Stock had been issued upon the exercise of Common Warrants (including net exercises) and Common Warrants to purchase 130,823 shares of Viracta Common Stock remain unexercised. These shares have been included in the weighted average shares outstanding for both basic and diluted earnings per share for the three and six months ended June 30, 2021 and 2020 as their exercise price is for nominal consideration. In July 2020, the Company issued warrants exercisable for 206,440 shares of Series E preferred stock, at an exercise price of $ 0.6055 per share, to Silicon Valley Bank in conjunction with the Company’s entry into the SVB Loan Agreement (the “Lender Warrants”). Upon completion of the Merger, the Lender Warrants became exercisable for 23,100 shares of common stock at an exercise price of $ 5.42 per share. The Lender Warrants will expire on July 30, 2030. Common Stock Reserved for Future Issuance Common stock reserved for future issuance are as follows in common equivalent shares: June 30, 2021 December 31, 2020 Conversion of preferred stock 292,799 18,811,552 Common stock warrants 153,923 193,266 Preferred stock warrants — 23,100 Stock options issued and outstanding for all plans 3,532,733 1,127,840 RSUs outstanding 852,186 — Authorized for future option grants 820,229 1,108,809 Common stock authorized for the ESPP 60,948 — Total 5,712,818 21,264,567 Equity Incentive Plans In January 2017, the Company adopted the Viracta Therapeutics, Inc. 2016 Equity Incentive Plan (the “2016 Plan”), which permitted stock option and restricted stock unit grants to employees, members of the board of directors, and outside consultants. The Plan allowed for grants of incentive stock options with exercise prices of at least 100 % of the fair market value of Viracta’s common stock, nonqualified options with exercise prices of at least 85 % of the fair market value of the Company’s common stock, restricted stock, and restricted stock units. All stock options granted under the 2016 Plan have a ten-year life and generally vest over zero to four years . In connection with the closing of the Merger, no further awards will be made under the 2016 Plan but the 2016 Plan will continue to govern the terms and conditions of the outstanding awards previously granted under the 2016 Plan. At the time of the close of the Merger, the Company adopted the Viracta Therapeutics, Inc. 2021 Equity Incentive Plan (the “2021 Plan”), which also permits stock options and restricted stock unit grants to employees, members of the board of directors, and outside consultants. The maximum number of shares of the Company’s common stock available for issuance under the 2021 Plan equals the sum of (a) 2,628,571 shares; (b) any shares of common stock of the Company which are subject to awards under the Sunesis 2011 Equity Incentive Plan (the “Sunesis 2011 Plan”) or the 2016 Plan as of the effective date of the 2021 Plan which become available for issuance under the 2021 Plan after such date in accordance with its terms; and (c) an annual increase on the first day of each calendar year beginning with January 1 of the calendar year following the effectiveness of the 2021 Plan and ending with the last January 1 during the initial ten year term of the 2021 Plan. This annual increase would be equal to the lesser of (i) 3,771,428 shares, (ii) five percent of the number of shares of the Company’s common stock outstanding (on an as-converted basis) on the final day of the immediately preceding calendar year, and (iii) such number of shares of the Company’s common stock as determined by the Company’s board of directors. The 2021 Plan allows for grants of incentive stock options with exercise prices of at least 100 % of the fair market value of Viracta’s common stock, nonqualified options with exercise prices of at least 100 % of the fair market value of the Company’s common stock, restricted stock, and restricted stock units. All stock options granted to date have a ten-year life and generally vest over zero to four years. Additionally, in connection with the closing of the Merger, no further awards will be made under the Sunesis 2011 Plan. As of June 30, 2021 , 100,394 fully vested options remain outstanding under the Sunesis 2011 Plan with a weighted average exercise price of $ 34.15 per share. The compensation cost that has been included in the accompanying condensed consolidated statements of operations for all share-based compensation arrangements is detailed as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Research and development $ 435 $ 28 $ 742 $ 57 General and administrative 951 40 1,288 98 Total $ 1,386 $ 68 $ 2,030 $ 155 On June 30, 2021, the Company adopted the 2021 Inducement Equity Incentive Plan (the “2021 Inducement Plan”) and reserved 1,000,000 shares for future grant under the 2021 Inducement Plan. As of June 30, 2021, there were 1,000,000 shares available for issuance under the 2021 Inducement Plan. Stock Options The Company recorded share-based compensation of $ 1.2 million and $ 0.1 million for the three months ended June 30, 2021 and 2020 , respectively, and $ 1.7 million and $ 0.2 million for the six months ended June 30, 2021 and 2020, respectively. Fair value is determined on the date of grant for options. Compensation expense is recognized over the vesting period based on the fair value of the options. The fair value of stock options is estimated using the Black-Scholes model with the assumptions disclosed in the following table (no grants were made during the six months ended June 30, 2020): Six Months Ended June 30, 2021 Risk free interest rate 0.66 % - 1.24 % Expected option term 5.8 - 6.3 years Expected volatility of common stock 88.6 % - 90.2 % Expected dividend yield 0 % The expected term of stock options is based on the simplified method, which is an average of the contractual term of the option and its vesting period. The expected volatility of stock options is based upon the historical volatility of a number of publicly traded companies in similar stages of clinical development. The risk-free interest rate is based on the average yield of U.S. Treasury Bills appropriate for the expected term of the stock option grants. The Company has not historically paid cash dividends and does not anticipate declaring dividends in the future. As of June 30, 2021 , unrecognized compensation expense related to unvested options granted totaled $ 15.8 million. The expense is expected to be recognized over a weighted-average period of 3.3 years. A summary of the stock option activity under the 2016 Plan and the 2021 Plan during the period ended June 30, 2021 is presented below (in thousands except for per share and weighted average term): Number of Weighted Weighted Outstanding at December 31, 2020 1,128 $ 1.08 8.5 Granted 2,509 $ 8.48 Exercised ( 169 ) $ 1.03 Cancelled ( 35 ) $ 3.37 Outstanding at June 30, 2021 3,433 $ 6.47 9.3 Outstanding at June 30, 2021 (Sunesis 2011 Plan) 100 $ 34.15 4.3 Restricted Stock Units The Company recorded share-based compensation of $ 225,000 and $ 0 for the three months ended June 30, 2021 and 2020 , respectively, and $ 300,000 and $ 0 for the six months ended June 30, 2021 and 2020, respectively. For RSU equity awards, grant date fair value is estimated using the closing stock price on the date of grant. Compensation expense is recognized over the vesting period based on the fair value of the RSUs. A summary of the restricted stock unit activity under the plans during the period ended June 30, 2021 is presented below (in thousands except for per share and weighted average term): RSUs Weighted Weighted Outstanding at December 31, 2020 — $ — — Granted 852 4.22 Vested — — Cancelled — — Outstanding at June 30, 2021 852 $ 4.22 3.7 As of June 30, 2021 , unrecognized compensation expense related to unvested RSUs totaled $ 3.3 million. The expense is expected to be recognized over a weighted-average period of 3.7 years. Employee Stock Purchase Plan The Company adopted the 2011 Employee Stock Purchase Plan (the “2011 ESPP”) as part of the Merger. 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 value at more than $ 25,000 per calendar year. As of June 30, 2021 , there were 60,948 shares available for future issuance under the ESPP.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	8. Commitments and Contingencies Leases In 2018, the Company negotiated a one-year lease for its office (“Lease”). The effective date of the Lease was September 1, 2018. Under the terms of the Lease the rental rate was $ 14,132 per month. In June 2019, the Company amended the term of the Lease to extend the termination date to August 31, 2020 . Under the terms of the Lease amendment, the rental rate was $ 14,980 per month. Upon the Lease amendment, the Company no longer met the short-term lease exemption and recorded an operating lease right-of-use (“ROU”) asset and corresponding lease liability for $ 225,000 . In June 2020, the Company amended the Lease and another existing office lease to enter into a noncancelable operating lease to extend the lease term through August 2023 with a renewal option for an additional year (“Amended Lease”). The Amended Lease monthly base rent will increase approximately 4 % annually from $ 20,019 to $ 21,444 over the life of the lease, including utilities and other operating costs. Upon the execution of the Amended Lease, the Company recorded an operating lease ROU asset and corresponding lease liability for $ 667,000 . In August 2020, the Company entered into an additional noncancelable operating lease agreement for certain office space with a lease term from August 2020 through August 2023 with a renewal option for an additional year (“New Lease”). The New Lease also includes a buyout option to terminate the lease prior to its expiration with at least one month’s prior written notice and a one-time payment equal to four months’ rent. The New Lease monthly base rent will increase approximately 4 % to 9 % from $ 12,462 to $ 14,033 over the life of the lease, including utilities and other operating costs. In connection with the execution of the New Lease, the Company recorded an operating lease ROU asset and corresponding lease liability for $ 439,000 . Total lease expense for the three months ended June 30, 2021 and 2020 was $ 329,000 and $ 60,000 , respectively, and for the six months ended June 30, 2021 and 2020 was $ 401,000 and $ 107,000 , respectively. At June 30, 2021, the Company had remaining lease liabilities of approximately $ 832,000 of which $ 474,000 was recorded as noncurrent lease liability as of June 30, 2021 , and operating lease ROU assets of $ 816,000 . Total cash paid for amounts included in the measurement of operating lease liabilities was $ 247,000 and $ 108,000 for the three months ended June 30, 2021 and 2020 , respectively, and was $ 344,000 and $ 162,000 for the six months ended June 30, 2021 and 2020 , respectively. The weighted average discount rate for the operating leases recorded during the twelve months ended December 31, 2020 was 8.0 % and the weighted average remaining lease term was 2 years as of June 30, 2021. Indemnifications As permitted under Delaware law, the Company indemnifies its officers, directors, and employees for certain events and occurrences while the officer, or director is, or was, serving at the Company’s request in such capacity.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries and have been prepared in accordance with GAAP and follow the requirements of the U.S. Securities and Exchange Commission (“SEC”) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by GAAP can be condensed or omitted. In management’s opinion, the unaudited interim financial statements have been prepared on the same basis as the audited financial statements and include all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of the Company’s financial position and its results of operations and its cash flows for the periods presented. These statements do not include all disclosures required by GAAP and should be read in conjunction with the Company’s financial statements and accompanying notes for the year ended December 31, 2020 , which are contained in the Company’s Current Report on Form 8-K/A filed with the SEC on March 23, 2021. The results for interim periods are not necessarily indicative of the results expected for the full fiscal year or any other interim period.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Actual results could differ materially from those estimates.
Concentrations of Credit Risk	Concentrations of Credit Risk Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash and cash equivalents. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company has not experienced any losses in such accounts and believes it is not exposed to significant risk on its cash and cash equivalents.
Significant Accounting Policies	Significant Accounting Policies On January 1, 2018, the Company adopted the provisions of ASC 610-20, Gain or Loss From Derecognition of Non-financial Assets (“ASC 610-20”). In accordance with ASC 610-20, the Company recognizes any gains when the Company transfers control of a property and when it is probable that the Company will collect substantially all of the related consideration. The Company had no transactions since the adoption except for on March 22, 2021, the Company entered into a Royalty Purchase Agreement with XOMA (US) LLC (“XOMA”), in which XOMA purchased the potential future milestones and royalties associated with existing licenses relating to two clinical-stage product candidates, DAY101 and vosaroxin, which were obtained in the Merger. The Company received an upfront payment of $ 13.5 million and may receive up to $ 20.0 million in a pre-commercialization, event-based milestone. There have been no other material changes in the Company’s accounting policies from those disclosed in the audited financial statements and related notes thereto as of and for the year ended December 31, 2020, which are contained in the Company’s Current Report on Form 8-K/A filed with the SEC on March 23, 2021.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity from the date of purchase of three months or less to be cash equivalents. Cash and cash equivalents include cash in readily available check and money market accounts.
Clinical Trial and Contracts Accruals	Clinical Trial and Contracts Accruals Clinical trial costs include payments to sites participating in clinical trials and to outside contract research organizations that assist in developing, monitoring and administering the clinical trials. Measurement of clinical trial expenses and the related accrual recorded in any given period requires judgment as invoices or other notification of actual costs may not exist as of the date of the financial statements, making it necessary to estimate the efforts completed to date and the related expense. The period over which services are performed, the level of services performed as of a given date, and the cost of such services are often subjective determinations. The Company’s principal vendors operate within terms of contracts which establish program costs and estimated timelines. The status of the Company’s programs is assessed in relation to the scope of work outlined in the contracts, and the related amount of expense is recognized accordingly. Estimates are adjusted to actual costs as they become known and subsequent changes to estimates have not historically resulted in a material change to the accruals.
Research and Development Expenses	Research and Development Expenses Research and development costs are expensed as incurred. These costs consist primarily of salaries and other personnel-related expenses, including share-based compensation; facility-related expenses; and services performed by clinical research organizations, research institutions, and other outside service providers. The Company recorded the estimated costs of research and development activities based upon the estimated amount of services provided but not yet invoiced and include these costs in accrued expenses in the balance sheet and within research and development expense in the statement of operations and comprehensive loss. As actual costs become known, the Company will adjust its accrued expenses and related research and development expenses.
Share-Based Compensation	Share-Based Compensation Share-based compensation expense for stock option grants and restricted stock units (“RSUs”) under the Company’s equity plans are recorded at the estimated fair value of the award as of the grant date and recognized as expense on a straight-line basis over the requisite service period of the stock-based award, and forfeitures are recognized as they occur. The estimate of fair value for share-based compensation for stock options requires management to make estimates and judgments about, among other things, employee exercise behavior and volatility of the Company’s common stock. The judgments directly affect the amount of compensation expense that will be recognized.
Segment Reporting	Segment Reporting Operating segments are identified as components of an enterprise about which separate discrete financial information is used in making decisions regarding resource allocation and assessing performance. To date, the Company has viewed its operations and managed its business as one segment operating in the United States. All long-lived assets were located in the United States at June 30, 2021 .
Fair Value Measurements	Fair Value Measurements The accounting guidance defines fair value, establishes a consistent framework for measuring fair value and expands disclosure for each major asset and liability category measured at fair value on either a recurring or non-recurring basis. Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market- based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the accounting guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows: Level 1: Observable inputs such as quoted prices in active markets. Level 2: Inputs, other than the quoted prices in active markets that are observable either directly or indirectly. Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. The carrying amounts of the Company’s cash and cash equivalents, prepaid expenses, accounts payable and accrued liabilities approximate fair values for these financial instruments due to their short maturities. The preferred stock warrant liability, a level 3 fair value measurement, was $ 0 as of June 30, 2021 , due to the reclassification to equity, and $ 106,000 as of December 31, 2020. The Company had no assets or liabilities measured at fair value on a recurring basis as of June 30, 2021 . The Company had no assets or liabilities measured at fair value on a recurring basis as of December 31, 2020, other than the preferred stock warrant liability.
Preferred Stock Warrant Liability	Preferred stock warrant liability The assumptions used in the Black-Scholes option pricing model to determine the fair value of the preferred stock warrant liability were as follows: February 24, 2021 Expected volatility 90.2 % Risk-free interest rate 1.38 % Expected dividend yield 0 % Expected term 9.3 years Fair value per share of preferred stock $ 17.15 The following table provides a reconciliation of the preferred stock warrant liability measured at fair value using Level 3 significant unobservable inputs (in thousands): Preferred Stock Balance at December 31, 2020 $ 106 Change in fair value of preferred stock warrant liability 290 Reclassification to equity ( 396 ) Balance at June 30, 2021 $ —
Net Loss Per Share	Net Loss Per Share Basic loss per common share is computed by dividing net loss by the weighted average number of common shares and warrants to purchase common stock for nominal consideration outstanding during the period. Diluted loss per common share is computed by dividing net loss by the weighted average number of common shares outstanding, plus the impact of common shares, if dilutive, resulting from the exercise of outstanding common stock equivalents. The following securities are excluded from the calculation of weighted average dilutive common shares because their inclusion would have been anti-dilutive: June 30, 2021 2020 Shares issuable upon conversion of preferred stock 292,799 11,419,329 Common stock options and RSUs outstanding 4,384,919 1,567,851 Warrants to purchase common stock 23,100 — Total excluded securities 4,700,818 12,987,180
Recent Accounting Pronouncements	Recent Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instruments , which will require a reporting entity to use a new forward-looking impairment model for most financial assets that generally will result in the earlier recognition of allowances for losses. For available-for-sale debt securities with unrealized losses, credit losses will be recognized as allowances rather than as reductions in amortized cost. Entities will apply the guidance as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is adopted. In April 2019, the FASB issued ASU 2019-04, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments , to increase stakeholders’ awareness of the amendments and to expedite improvements to the Codification. In May 2019, the FASB issued ASU 2019-05, Financial Instruments—Credit Losses, Topic 326 , providing an option to irrevocably elect the fair value option for certain financial assets previously measured at amortized cost basis. These ASUs do not change the core principle of the guidance in ASU 2016-13. Instead these amendments are intended to clarify and improve operability of certain topics. In November 2019, FASB issued ASU 2019-10, Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842): Effective Dates and ASU 2019-11, Codification Improvements to Topic 326, Financial Instruments—Credit Losses , which defers the effective dates of the new credit losses standard for all entities except SEC filers that are not smaller reporting companies to fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. The standard and other related subsequently issued ASUs will be effective for the Company for annual periods beginning after December 15, 2022, with early adoption permitted. The Company is currently evaluating the impact that the adoption of the standard and other related subsequently issued ASUs will have on its financial statements and accompanying footnotes. 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) . The amendments in this ASU reduce the number of accounting models for convertible debt instruments and convertible preferred stock, as well as amend the guidance for the derivatives scope exception for contracts in an entity’s own equity to reduce form-over-substance-based accounting conclusion. In addition, this ASU improves and amends the related earnings per share guidance. The amendments in this ASU are effective for the Company on January 1, 2024, including interim periods within those fiscal years. Early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2020, including interim periods within those fiscal years. Adoption is either a modified retrospective method or a fully retrospective method of transition. The Company early adopted ASU 2020-06 on January 1, 2021, electing the modified retrospective transition method that allows for a cumulative-effect adjustment in the period of adoption. The adoption of ASU 2020-06 did not have a material impact on the Company’s financial statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Summary of Fair Value Measurement Inputs and Valuation Techniques	The assumptions used in the Black-Scholes option pricing model to determine the fair value of the preferred stock warrant liability were as follows: February 24, 2021 Expected volatility 90.2 % Risk-free interest rate 1.38 % Expected dividend yield 0 % Expected term 9.3 years Fair value per share of preferred stock $ 17.15
Summary of reconciliation of warrant liability measured at fair value	The following table provides a reconciliation of the preferred stock warrant liability measured at fair value using Level 3 significant unobservable inputs (in thousands): Preferred Stock Balance at December 31, 2020 $ 106 Change in fair value of preferred stock warrant liability 290 Reclassification to equity ( 396 ) Balance at June 30, 2021 $ —
Summary of antidilutive securities excluded from the calculation of weighted average dilutive common shares	The following securities are excluded from the calculation of weighted average dilutive common shares because their inclusion would have been anti-dilutive: June 30, 2021 2020 Shares issuable upon conversion of preferred stock 292,799 11,419,329 Common stock options and RSUs outstanding 4,384,919 1,567,851 Warrants to purchase common stock 23,100 — Total excluded securities 4,700,818 12,987,180

Financial Statement Details (Ta

Financial Statement Details (Tables)	6 Months Ended
	Jun. 30, 2021
Financial Statement Details [Abstract]
Schedule of Accrued Liabilities	Accrued expenses consist of the following (in thousands): June 30, December 31, Accrued payroll and benefits $ 1,001 $ 1,501 Accrued clinical trial and contract expenses 1,331 1,095 Accrued professional services and expenses 342 716 Other accrued expenses 522 50 Total accrued expenses $ 3,196 $ 3,362

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Summary of Future Minimum Payments Under Loan Facility	The following table summarizes future minimum payments under the term loan facility as of June 30, 2021 (in thousands): Year Ending December 31, 2021 $ 172 2022 2,123 2023 2,154 2024 1,543 Total future minimum payments 5,992 Less: interest payments ( 1,004 ) Principal amount of long-term debt 4,988 Current portion of long-term debt ( 833 ) Long-term debt, net $ 4,155

Merger (Tables)

Merger (Tables)	6 Months Ended
	Jun. 30, 2021
Business Combinations [Abstract]
Summary of Allocation of the Purchase Price To Assets and Liabilities Acquired	The allocation of the purchase price is as follows (in thousands): Net assets acquired (1) $ 18,956 Acquired IPR&D (2) 84,478 Purchase price $ 103,434 (1) Net assets acquired (in thousands): Cash and cash equivalents $ 17,143 Prepaid expenses and other assets 3,768 Accounts payable and accrued liabilities ( 1,955 ) Net assets acquired $ 18,956 (2) Represents the research and development projects of Sunesis which were in-process, but not yet completed. Current accounting standards require that the fair value of IPR&D projects acquired in an asset acquisition with no alternative future use be allocated a portion of the consideration transferred and charged to expense on the acquisition date. The acquired IPR&D assets did not have outputs or employees.

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	6 Months Ended
	Jun. 30, 2021
Stockholders' Equity Note [Abstract]
Shares of Common Stock Reserved for Future Issuance	Common stock reserved for future issuance are as follows in common equivalent shares: June 30, 2021 December 31, 2020 Conversion of preferred stock 292,799 18,811,552 Common stock warrants 153,923 193,266 Preferred stock warrants — 23,100 Stock options issued and outstanding for all plans 3,532,733 1,127,840 RSUs outstanding 852,186 — Authorized for future option grants 820,229 1,108,809 Common stock authorized for the ESPP 60,948 — Total 5,712,818 21,264,567
Summary of fair value of stock options is estimated using the Black-Scholes model	The fair value of stock options is estimated using the Black-Scholes model with the assumptions disclosed in the following table (no grants were made during the six months ended June 30, 2020): Six Months Ended June 30, 2021 Risk free interest rate 0.66 % - 1.24 % Expected option term 5.8 - 6.3 years Expected volatility of common stock 88.6 % - 90.2 % Expected dividend yield 0 %
Summary of Stock Option Activity for Company's Stock Option Plans	A summary of the stock option activity under the 2016 Plan and the 2021 Plan during the period ended June 30, 2021 is presented below (in thousands except for per share and weighted average term): Number of Weighted Weighted Outstanding at December 31, 2020 1,128 $ 1.08 8.5 Granted 2,509 $ 8.48 Exercised ( 169 ) $ 1.03 Cancelled ( 35 ) $ 3.37 Outstanding at June 30, 2021 3,433 $ 6.47 9.3 Outstanding at June 30, 2021 (Sunesis 2011 Plan) 100 $ 34.15 4.3
Summary of Shared Based Compensation Cost Included in Condensed Statement Of Operations	The compensation cost that has been included in the accompanying condensed consolidated statements of operations for all share-based compensation arrangements is detailed as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Research and development $ 435 $ 28 $ 742 $ 57 General and administrative 951 40 1,288 98 Total $ 1,386 $ 68 $ 2,030 $ 155 On June 30, 2021, the Company adopted the 2021 Inducement Equity Incentive Plan (the “2021 Inducement Plan”) and reserved 1,000,000 shares for future grant under the 2021 Inducement Plan. As of June 30, 2021, there were 1,000,000 shares available for issuance under the 2021 Inducement Plan.
Summary of Restricted Stock Units Activity	A summary of the restricted stock unit activity under the plans during the period ended June 30, 2021 is presented below (in thousands except for per share and weighted average term): RSUs Weighted Weighted Outstanding at December 31, 2020 — $ — — Granted 852 4.22 Vested — — Cancelled — — Outstanding at June 30, 2021 852 $ 4.22 3.7

Organization and Basis of Pre_2

Organization and Basis of Presentation - Additional Information (Detail) $ in Thousands	Feb. 24, 2021	Feb. 28, 2021USD ($)	Jun. 30, 2021USD ($)	Dec. 31, 2020USD ($)
Accumulated deficit			$ (139,316)	$ (50,915)
Cash and cash equivalents		$ 17,100	122,721	$ 47,089
Working capital			$ 118,200
Gross proceeds from private placement		$ 65,000
Reverse stock split	3.5-for-one
Percentage of outstanding common stock of combined company			86.00%
Conversion ratio			0.1119
Royalty Purchase Agreement [member]
Upfront payment received			$ 13,500
Private Placement [Member]
Gross proceeds from private placement			$ 65,000

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Summary of Fair Value Measurement Inputs and Valuation Techniques (Detail) - Preferred Stock Warrant Liability [Member]	Feb. 24, 2021yrUsDollarsShare
Measurement Input, Price Volatility [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	90.2
Measurement Input, Risk Free Interest Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	1.38
Measurement Input, Expected Dividend Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0
Measurement Input, Expected Term [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input | yr	9.3
Measurement Input, Share Price [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input | UsDollarsShare	17.15

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Summary of Reconciliation of Warrant Liability Measured at Fair Value (Detail) - Preferred Stock Warrant Liability [Member] $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Opening , Balance	$ 106
Change in fair value of preferred stock warrant liability	290
Reclassification to equity	(396)
Ending , Balance	$ 0

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2021USD ($)Segment	Dec. 31, 2020USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value on recurring basis	$ 0
Preferred stock warrant liability noncurrent	$ 0	$ 106,000
United States [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of reportable segment | Segment	1
Fair Value, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred stock warrant liability noncurrent	$ 0	$ 106,000
Royalty Purchase Agreement [member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Upfront payment received	13,500,000
Milestone payment received in the future	$ 20,000,000

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Summary of Antidilutive Securities Excluded From the Calculation of Weighted Average Dilutive Common Shares (Detail) - shares	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	4,700,818	12,987,180
Shares issuable upon conversion of preferred stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	292,799	11,419,329
Common stock options and RSUs outstanding [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	4,384,919	1,567,851
Warrants to purchase common stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	23,100	0

Financial Statement Details -

Financial Statement Details - Schedule of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Accrued payroll and benefits	$ 1,001	$ 1,501
Accrued clinical trial and contract expenses	1,331	1,095
Accrued professional services and expenses	342	716
Other accrued expenses	522	50
Total accrued expenses	$ 3,196	$ 3,362

XOMA Transaction - Additional i

XOMA Transaction - Additional information (Detail) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2019
Royalty Purchase Agreement [member]
Upfront payment received	$ 13.5
Milestone payment received in the future	$ 20
DOT-1 License Agreement [Member] | License Agreement Terms [Member]
Potential pre-commercialization payments receivable		$ 57
Development milestone payment received		3
Denovo License Agreement [Member] | License Vosaroxin [Member]
Regulatory, commercial milestones payments and double-digit royalty payments, receivable		$ 57

Debt - Additional Information (

Debt - Additional Information (Detail) - USD ($)	Apr. 24, 2020	Jun. 30, 2021	Jul. 30, 2020
SVB Loan Agreement [Member]
Debt [Line Items]
Debt Instrument, Face Amount		$ 5,000,000
Payment Protection Program Loan [Member]
Debt [Line Items]
Debt Instrument, Maturity Date	Apr. 23, 2022
Debt Instrument, Interest Rate	1.00%
Debt Instrument, Increase (Decrease), Net		257,000
Debt and Lease Obligation		$ 0
Silicon Valley Bank [Member] | Maximum [Member]
Debt [Line Items]
Prepayment Fee Percentage		2.00%
Silicon Valley Bank [Member] | Minimum [Member]
Debt [Line Items]
Prepayment Fee Percentage		1.00%
First Republic Bank [Member] | Payment Protection Program Loan [Member]
Debt [Line Items]
Proceeds from Long-term Lines of Credit	$ 253,700
Term Loan Agreement [Member] | Silicon Valley Bank [Member]
Debt [Line Items]
Line of credit maximum borrowing amount			$ 15,000,000
Line of credit additional borrowing amount		$ 10,000,000
Debt Instrument, Maturity Date		Jul. 1, 2024
Debt Instrument, Interest Rate		6.75%
Debt Instrument Final Payment Interest Fee Percentage		7.00%
Term Loan Agreement [Member] | Silicon Valley Bank [Member] | Prime Rate [Member]
Debt [Line Items]
Debt Instrument, Interest Rate During Period		10.00%
Debt Instrument, Basis Spread on Variable Rate		3.50%

Debt - Summary of Future Minimu

Debt - Summary of Future Minimum Payments Under Loan Facility (Detail) $ in Thousands	Jun. 30, 2021USD ($)
Debt Instrument [Line Items]
2021	$ 172
2022	2,123
2023	2,154
2024	1,543
Total Future minimum payments	5,992
Less: interest payments	1,004
Principal amount of long-term debt	4,988
Current portion of long-term debt	833
Long-term debt, net	$ 4,155

Merger - Additional Information

Merger - Additional Information (Detail) $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2021USD ($)$ / sharesshares
Business Acquisition [Line Items]
Estimated Fair value of total consideration | $	$ 103.4
Share price | $ / shares	$ 18.62
Transaction costs | $	$ 1.6
Common Stock [Member]
Business Acquisition [Line Items]
Number of shares of common stock outstanding prior to the merger date	5,173,772
Shares issuable upon conversion of preferred stock [Member]
Business Acquisition [Line Items]
Number of shares of convertible preferred stock outstanding prior to merger	10,248
Common Stock Convertible Basis [Member]
Business Acquisition [Line Items]
Number of shares of Common stock as a convertible basis outstanding prior to merger	292,799

Merger - Summary of Allocation

Merger - Summary of Allocation of the Purchase Price To Assets and Liabilities Acquired (Detail) $ in Thousands	Jun. 30, 2021USD ($)
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Net assets acquired	$ 18,956
Acquired IPR&D	84,478
Purchase price	103,434
Net assets acquired
Cash and cash equivalents	17,143
Prepaid expenses and other assets	3,768
Accounts payable and accrued liabilities	(1,955)
Net assets acquired	$ 18,956

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($)	May 28, 2021	Feb. 24, 2021	Jan. 01, 2020	Jan. 31, 2017	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Jul. 30, 2020
Stockholders Equity [Line Items]
Common stock, shares outstanding					37,140,817		905,987			37,140,817
Convertible Preferred Stock, Shares Issued upon Conversion							18,811,552
Preferred stock, shares authorized					10,000,000		10,000,000			10,000,000
Preferred stock, shares outstanding					10,248					10,248
Share of common stock value					$ 25,000					$ 25,000
Weighted average exercise price					$ 6.47		$ 1.08			$ 6.47
Stock reserved for future grant					5,712,818		21,264,567			5,712,818
Stock-based compensation					$ 1,386,000			$ 68,000		$ 2,030,000	$ 155,000
Stock option plan weighted average vesting period							8 years 6 months			9 years 3 months 18 days
Twenty Thousand and Sixteen Equity Incentive Plan [Member]
Stockholders Equity [Line Items]
Options granted period										10 years
2021 Equity Incentive Plan [Member]
Stockholders Equity [Line Items]
Common stock available for issuance automatic increase period			10 years
Shares of common stock available for issuance			3,771,428							2,628,571
Shares Available for Future Grant					100,394					100,394
Purchase price of a share as a percentage of fair market value										100.00%
Percentage Of Nonqualified Options Exercisable Price Of Fair Market Value Of Common Stock										100.00%
Weighted average exercise price					$ 34.15					$ 34.15
2021 Inducement Plan [Member]
Stockholders Equity [Line Items]
Shares of common stock available for issuance										1,000,000
Stock reserved for future grant					1,000,000					1,000,000
Stock Options [Member]
Stockholders Equity [Line Items]
Stock-based compensation					$ 1,200,000			$ 100,000		$ 1,700,000	200,000
Stock option plan weighted average vesting period										3 years 3 months 18 days
Unrecognised compensation expense related to unvested units					$ 15,800,000					$ 15,800,000
Incentive Stock Options [Member] | Twenty Thousand and Sixteen Equity Incentive Plan [Member]
Stockholders Equity [Line Items]
Percentage of exercise price fair value				100.00%
Nonqualified Options [Member] | Twenty Thousand and Sixteen Equity Incentive Plan [Member]
Stockholders Equity [Line Items]
Percentage of exercise price fair value				85.00%
Restricted Stock Units [Member]
Stockholders Equity [Line Items]
Stock reserved for future grant					852,186		0			852,186
Stock-based compensation					$ 225,000				$ 0	$ 300,000	$ 0
Unrecognised compensation expense related to unvested units					$ 3,300,000					$ 3,300,000
Restricted Stock units plan weighted average vesting period										3 years 8 months 12 days
Preferred Stock Warrants [Member]
Stockholders Equity [Line Items]
Stock reserved for future grant					0		23,100			0
Minimum [Member] | Twenty Thousand and Sixteen Equity Incentive Plan [Member]
Stockholders Equity [Line Items]
Options,vesting period										0 years
Maximum [Member] | Twenty Thousand and Sixteen Equity Incentive Plan [Member]
Stockholders Equity [Line Items]
Options,vesting period										4 years
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					$ 0.0001					$ 0.0001
Percentage of outstanding common stock					9.98%					9.98%
Shares issuable upon conversion of preferred stock [Member]
Stockholders Equity [Line Items]
Stock reserved for future grant					292,799		18,811,552			292,799
Series E Convertible Preferred Stock [Member]
Stockholders Equity [Line Items]
Price per common share					$ 500					$ 500
Preferred stock, shares outstanding					1,915					1,915
Convertible share price per share					$ 17.50					$ 17.50
Series F Convertible Preferred Stock [Member]
Stockholders Equity [Line Items]
Price per common share					$ 600					$ 600
Preferred stock, shares outstanding					8,333					8,333
Convertible share price per share					$ 21					$ 21
Warrant [Member] | Preferred Stock Warrants [Member]
Stockholders Equity [Line Items]
Class of warrant or right, exercise price of warrants or rights												$ 0.6055
Issue of warrants exercisable												206,440
Warrant [Member] | Preferred Stock Warrants [Member] | Silicon Valley Bank [Member]
Stockholders Equity [Line Items]
Class of warrant or right, exercise price of warrants or rights												$ 5.42
Issue of warrants exercisable												23,100
Common Stock [Member]
Stockholders Equity [Line Items]
Stock issued during period						5,173,000
Stock Issued During Period, Shares, New Issues						12,012,000
Common Stock [Member] | Common Warrants [Member]
Stockholders Equity [Line Items]
Class of warrant or right, exercise price of warrants or rights					$ 0.09		$ 0.09			$ 0.09
Class of warrant or right issued in period of warrants or rights					250,323		250,323			250,323
Class of warrant or right issued remain unexercised										130,823
Warrant expiration period						7 years
Stock issued during period										118,982
Employee Stock Purchase Plan [Member]
Stockholders Equity [Line Items]
Shares Available for Future Grant					60,948					60,948
Purchase price of a share as a percentage of fair market value										85.00%
Duration of offering period										12 months
Duration of each purchase period										6 months
Stock reserved for future grant					60,948		0			60,948
Private Placement [Member] | Common Stock [Member]
Stockholders Equity [Line Items]
Proceeds from issuance initial public offering		$ 65,000,000
Adjustments to additional paid in capital stock issuance costs		$ 2,700,000
Stock Issued During Period, Shares, New Issues		12,012,369
Sales Agreement [Member]
Stockholders Equity [Line Items]
Common stock par value	$ 0.0001
Legal and accounting cost										$ 100,000
Sales Agreement [Member] | Maximum [Member]
Stockholders Equity [Line Items]
Potential sales of common stock	$ 50,000,000

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Shared Based Compensation Cost Included in Condensed Statement Of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share Based Compensation Cost Included in Condensed Statement Of Operations [Line Items]
Total stock-based compensation expense	$ 1,386	$ 68	$ 2,030	$ 155
Research and development [Member]
Share Based Compensation Cost Included in Condensed Statement Of Operations [Line Items]
Total stock-based compensation expense	435	28	742	57
General and administrative [Member]
Share Based Compensation Cost Included in Condensed Statement Of Operations [Line Items]
Total stock-based compensation expense	$ 951	$ 40	$ 1,288	$ 98

Stockholders' Equity - Shares o

Stockholders' Equity - Shares of Common Stock Reserved for Future Issuance (Detail) - shares	Jun. 30, 2021	Dec. 31, 2020
Class of Stock [Line Items]
Total common stock reserved for future issuance	5,712,818	21,264,567
Authorized for future option grants [Member]
Class of Stock [Line Items]
Total common stock reserved for future issuance	820,229	1,108,809
Common stock warrants [Member]
Class of Stock [Line Items]
Total common stock reserved for future issuance	153,923	193,266
Preferred stock warrants [Member]
Class of Stock [Line Items]
Total common stock reserved for future issuance	0	23,100
Common stock authorized for the ESPP [Member]
Class of Stock [Line Items]
Total common stock reserved for future issuance	60,948	0
Stock options issued and outstanding for all plans [Member]
Class of Stock [Line Items]
Total common stock reserved for future issuance	3,532,733	1,127,840
RSUs outstanding [Member]
Class of Stock [Line Items]
Total common stock reserved for future issuance	852,186	0
Convertible preferred stock [Member]
Class of Stock [Line Items]
Total common stock reserved for future issuance	292,799	18,811,552

Stockholders' Equity - Summar_2

Stockholders' Equity - Summary of Fair Value of Stock Options is Estimated Using the Black-Scholes Model (Detail)	6 Months Ended
	Jun. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest rate	0.66%
Expected option term	5 years 9 months 18 days
Expected volatility of common stock	88.60%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest rate	1.24%
Expected option term	6 years 3 months 18 days
Expected volatility of common stock	90.20%

Stockholders' Equity - Summar_3

Stockholders' Equity - Summary of Stock Option Activity (Detail) - $ / shares shares in Thousands	3 Months Ended	6 Months Ended
	Dec. 31, 2020	Jun. 30, 2021
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Outstanding, Beginning Balance, Number of Shares		1,128
Outstanding, Beginning Balance, Weighted Average Exercise Price Per Share		$ 1.08
Options granted , Numbers of Shares		2,509
Options granted, Weighted Average Exercise Price Per Share		$ 8.48
Options exercised , Numbers of Shares		(169)
Options exercised, Weighted Average Exercise Price Per Share		$ 1.03
Options Cancelled , Number of Shares		(35)
Options Cancelled , Weighted average exercise price		$ 3.37
Outstanding, Ending Balance, Number of Shares	1,128	3,433
Outstanding, Ending Balance, Weighted Average Exercise Price Per Share	$ 1.08	$ 6.47
Outstanding, Weighted Average Remaining Contractual Term (Years)	8 years 6 months	9 years 3 months 18 days
2011 Plan [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Outstanding, Ending Balance, Number of Shares		100
Outstanding, Ending Balance, Weighted Average Exercise Price Per Share		$ 34.15
Outstanding, Weighted Average Remaining Contractual Term (Years)		4 years 3 months 18 days

Stockholders' Equity - Summar_4

Stockholders' Equity - Summary of Restricted Stock Units Activity (Detail) shares in Thousands	6 Months Ended
	Jun. 30, 2021$ / sharesshares
Share-based Payment Arrangement [Abstract]
RSUs, Beginning balance | shares	0
RSUs, Granted | shares	852
RSUs, Vested | shares	0
RSUs, Cancelled | shares	0
RSUs, Ending balance | shares	852
Weighted Average Grant Date Fair Value per Share, Beginning balance | $ / shares	$ 0
Weighted Average Grant Date Fair Value per Share, Granted | $ / shares	4.22
Weighted Average Grant Date Fair Value per Share, Vested | $ / shares	0
Weighted Average Grant Date Fair Value per Share, Cancelled | $ / shares	0
Weighted Average Grant Date Fair Value per Share, Ending balance | $ / shares	$ 4.22
Weighted Average Remaining Contractual Term (Years)	3 years 8 months 12 days

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($)	Aug. 31, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2018	Dec. 31, 2020
Loss Contingencies [Line Items]
Lease liability				$ 832,000		$ 832,000
Operating lease right-of-use asset				816,000		816,000			$ 986,000
Operating Lease Expense				329,000	$ 60,000	401,000	$ 107,000
Lease liability noncurrent				474,000		474,000			$ 658,000
Cash paid for operating lease liability				$ 247,000	108,000	$ 344,000	162,000
Operating lease weighted average discount rate									8.00%
Operating lease weighted average remaining lease term				2 years		2 years
Option to extend the lease			option for an additional year
Original Operating Lease [Member]
Loss Contingencies [Line Items]
Lease rental rate per month								$ 14,132
Lease Term								1 year
Lease extended termination description		term of the Lease to extend the termination date to August 31, 2020
Original Operating Lease Amended [Member]
Loss Contingencies [Line Items]
Lease rental rate per month		$ 14,980
Lease liability		225,000
Operating lease right-of-use asset		$ 225,000
Noncancelable operating lease agreement [Member] | Amended Operating Lease [Member]
Loss Contingencies [Line Items]
Lease liability			$ 667,000		667,000		667,000
Operating lease right-of-use asset			$ 667,000		$ 667,000		$ 667,000
Description of Lease Term			August 2023
Percentage of increase in monthly base rent			4.00%		4.00%		4.00%
Additional noncancelable operating lease agreement [Member] | New Operating Lease [Member]
Loss Contingencies [Line Items]
Lease liability	$ 439,000
Operating lease right-of-use asset	$ 439,000
Description of Lease Term	August 2020 through August 2023
Lease extended termination description	option to terminate the lease prior to its expiration with at least one month’s prior written notice and a one-time payment equal to four months’ rent.
Option to extend the lease	option for an additional year
Maximum [Member] | Noncancelable operating lease agreement [Member] | Amended Operating Lease [Member]
Loss Contingencies [Line Items]
Lease rental rate per month			$ 21,444
Maximum [Member] | Additional noncancelable operating lease agreement [Member] | New Operating Lease [Member]
Loss Contingencies [Line Items]
Lease rental rate per month	$ 14,033
Percentage of increase in monthly base rent	9.00%
Minimum [Member] | Noncancelable operating lease agreement [Member] | Amended Operating Lease [Member]
Loss Contingencies [Line Items]
Lease rental rate per month			$ 20,019
Minimum [Member] | Additional noncancelable operating lease agreement [Member] | New Operating Lease [Member]
Loss Contingencies [Line Items]
Lease rental rate per month	$ 12,462
Percentage of increase in monthly base rent	4.00%