Viracta Therapeutics (VIRX) 10-K 14 Mar 23 2022 FY Annual report Financial data

Cover Page

Cover Page - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Mar. 06, 2023	Jun. 30, 2022
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
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		38,410,935
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	false
Securities Act 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
Entity Public Float			$ 145.7
City Area Code	858
Local Phone Number	400-8470
Document Annual 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
Auditor Name	Ernst & Young LLP
Auditor Location	San Diego, California
Auditor Firm ID	42
Documents Incorporated by Reference	Certain information required by Part III of this Annual Report on Form 10-K is incorporated by reference from the registrant's definitive proxy statement for the registrant's 2023 annual meeting of stockholders, which will be filed with the Securities and Exchange Commission within 120 days after the close of the registrant's fiscal year ended December 31, 2022

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current Assets:
Cash and cash equivalents	$ 36,773	$ 103,554
Short-term investments	54,270	0
Prepaid expenses and other current assets	2,704	1,719
Total current assets	93,747	105,273
Property and equipment, net	148	242
Operating lease right-of-use asset	266	640
Other assets	1,830	2,397
Total assets	95,991	108,552
Current Liabilities:
Accounts payable	2,540	2,901
Accrued expenses	7,193	5,802
Operating lease liabilities	278	381
Total current liabilities	10,011	9,084
Long-term debt, net	24,877	4,819
Operating lease liabilities, less current portion	0	278
Stockholders' equity (deficit):
Convertible preferred stock, $0.0001 par value; 10,000,000 shares authorized as of December 31, 2022; 10,248 shares issued and outstanding as of December 31, 2022 and December 31, 2021	5,452	5,452
Common stock, $0.0001 par value; 400,000,000 shares authorized; 38,345,140 and 37,424,863 shares issued and outstanding at December 31, 2022 and December 31, 2021, respectively	4	4
Additional paid-in capital	270,699	254,592
Accumulated other comprehensive loss	(178)	0
Accumulated deficit	(214,874)	(165,677)
Total stockholders' equity	61,103	94,371
Total liabilities and stockholders' equity (deficit)	$ 95,991	$ 108,552

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2022	Dec. 31, 2021
Preferred stock, par value	$ 0.0001
Preferred stock, shares authorized	10,000,000
Preferred stock, shares issued	10,248	10,248
Preferred stock, shares outstanding	10,248	10,248
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	38,345,140	37,424,863
Common stock, shares outstanding	38,345,140	37,424,863

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Operating expenses:
Research and development	$ 26,262	$ 23,861
Purchased and acquired in-process research and development	0	88,478
General and administrative	24,327	15,437
Total operating expenses	50,589	127,776
Gain on royalty purchase agreement	0	13,500
Loss from operations	(50,589)	(114,276)
Other income (expense):
Gain on forgiveness of PPP Loan	0	257
Interest income	1,171	38
Interest expense	(577)	(491)
Other income (expense)	798	(290)
Total other income (expense)	1,392	(486)
Net loss	(49,197)	(114,762)
Unrealized loss on short-term investments	(178)	0
Comprehensive loss	$ (49,375)	$ (114,762)
Net loss per share of common stock, basic	$ (1.30)	$ (3.60)
Net loss per share of common stock, diluted	$ (1.30)	$ (3.60)
Weighted-average shares used to compute basic net loss per share	37,790,981	31,870,067
Weighted-average shares used to compute diluted net loss per share	37,790,981	31,870,067

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Preferred Stock [Member]	Preferred Stock [Member] Series A-1 Convertible Preferred Stock [Member]	Preferred Stock [Member] Series B Convertible Preferred Stock [Member]	Preferred Stock [Member] Series C Convertible Preferred Stock [Member]	Preferred Stock [Member] Series D Convertible Preferred Stock [Member]	Preferred Stock [Member] Series E Convertible Preferred Stock [Member]	Preferred Stock [Member] Shares issuable upon conversion of preferred stock [Member]	AOCI Attributable to Parent [Member]
Beginning Balance at Dec. 31, 2020	$ (46,200)	$ 1	$ 4,714	$ (50,915)		$ 2,968	$ 15,484	$ 9,392	$ 16,589	$ 38,869
Beginning Balance, shares at Dec. 31, 2020		906				4,819	2,788	1,588	2,224	7,392
Exercise of warrants and stock options to purchase common stock	339		339
Issuance of common stock upon exercise of stock options and from employee stock plan		411
Vesting of restricted stock units, shares		107
Vesting of early exercise of stock options, shares		4
Vesting of early exercise of stock options,Value	3		3
Issuance of common stock net of issuance costs	62,317	$ 1	62,316
Issuance of common stock net of issuance costs, shares		12,012
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
Conversion of convertible preferred stock into common stock upon Merger	83,302	$ 2	83,300		$ (15,484)	$ (2,968)		$ (9,392)	$ (16,589)	$ (38,869)
Conversion of convertible preferred stock into common stock upon Merger, shares		18,812			(2,788)	(4,819)		(1,588)	(2,224)	(7,392)
Reclassification of preferred stock warrant liability to equity	396		396
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
Share-based compensation	5,542		5,542
Unrealized loss on short-term investments	0
Net loss	(114,762)			(114,762)
Ending Balance at Dec. 31, 2021	94,371	$ 4	254,592	(165,677)							$ 5,452
Ending Balance, shares at Dec. 31, 2021		37,425									10
Exercise of warrants and stock options to purchase common stock	$ 225		225
Issuance of common stock upon exercise of stock options and from employee stock plan	105,000	155
Issuance of common stock through "at the market" offering net shares	564
Issuance of common stock through "at the market" offering, net, Value	$ 2,331		2,331
Issuance of common stock upon vesting of restricted stock units		197
Vesting of early exercise of stock options, shares		4
Vesting of early exercise of stock options,Value	3		3
Share-based compensation	13,548		13,548
Unrealized loss on short-term investments	(178)											$ (178)
Net loss	(49,197)			(49,197)
Ending Balance at Dec. 31, 2022	$ 61,103	$ 4	$ 270,699	$ (214,874)							$ 5,452	$ (178)
Ending Balance, shares at Dec. 31, 2022		38,345									10

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Operating activities
Net loss	$ (49,197)	$ (114,762)
Adjustments to reconcile net loss to net cash used in by operating activities:
Gain on forgiveness of PPP Loan	0	(257)
Acquired in-process research and development	0	84,478
Purchased in-process research and development	0	4,000
Share-based compensation expense	13,548	5,542
Depreciation and amortization	210	178
Amortization of premiums and accretion of discounts on short-term investments, net	(626)	0
Change in fair value of preferred stock warrant liability	0	290
Change in operating assets and liabilities:
Prepaid expenses and other current assets	(985)	(1,045)
Other assets	567	884
Accounts payable	(361)	922
Accrued expenses	1,394	907
Lease liabilities, net	(7)	12
Net cash used in operating activities	(35,457)	(18,851)
Investing activities
Purchases of property and equipment	(45)	(252)
Purchased in-process research and development	0	(4,000)
Purchases of short-term investments	(70,620)	0
Proceeds from maturity of short-term investments	16,799	0
Cash acquired in connection with the Merger	0	17,143
Net cash (used in) provided by investing activities	(53,866)	12,891
Financing activities
Proceeds from debt, net of issuance costs	19,986	(234)
Issuance of common stock, net of issuance costs	2,331	62,320
Exercise of warrants and stock options to purchase common stock	225	339
Net cash provided by financing activities	22,542	62,425
Net (decrease) increase in cash and cash equivalents	(66,781)	56,465
Cash and cash equivalents at beginning of period	103,554	47,089
Cash and cash equivalents at end of period	36,773	103,554
Supplemental disclosure of cash flow information
Interest paid	454	343
Interest earned	1,171	38
Noncash financing activities
Warrant liability reclassification to equity	0	396
Issuance of convertible preferred stock upon merger	0	5,452
Conversion of convertible preferred stock into common stock upon Merger	0	83,302
Issuance of common stock upon Merger	$ 0	$ 97,982

Organization and Basis of Prese

Organization and Basis of Presentation	12 Months Ended
	Dec. 31, 2022
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 cancers. Viracta’s lead product candidate is an all-oral combination therapy of its proprietary investigational drug, nanatinostat and the antiviral agent valganciclovir (collectively referred to as “Nana-val”). Nana-val is currently being investigated in multiple ongoing clinical trials, including NAVAL-1, a pivotal, global, multicenter, open-label Phase 2 basket trial for the treatment of multiple subtypes of relapsed/refractory (“R/R”) Epstein-Barr virus-positive (“EBV + ”) lymphoma, as well as a multinational, open-label Phase 1b/2 trial for the treatment of EBV + recurrent or metastatic nasopharyngeal carcinoma (“R/M NPC”) and other EBV + solid tumors. Viracta’s development pipeline also includes vecabrutinib, a clinical-stage non-covalent ITK/BTK inhibitor and VRx-510 (formerly SNS-510), a preclinical-stage PDK-1 inhibitor. Viracta is evaluating future development and collaboration opportunities for vecabrutinib in combination with chimeric antigen receptor (“CAR”) T-cell therapies and VRx-510 in multiple oncology and other indications. 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 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 effectuated upon the Merger. Liquidity and Risks As of December 31, 2022, 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 December 31, 2022, had an accumulated deficit of $ 214.9 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 December 31, 2022, the Company had cash, cash equivalents and short-term investments of approximately $ 91.0 million and working capital of $ 83.7 million. As of the date of filing this Annual Report on Form 10-K, the Company has access to and control over all its cash, cash equivalents and short-term investments, notwithstanding the closure of SVB (see Note 11). On November 4, 2021, the Company entered into a loan and security agreement with Silicon Valley Bank (“SVB”) and Oxford Finance LLC (“Oxford”), collectively referred to as “Lenders,” for up to $ 50.0 million, with $ 5.0 million refinanced at the time of entering into the agreement and $ 45.0 million available under certain circumstances, as amended August 26, 2022. The second tranche of $ 20.0 million was drawn by the Company on December 29, 2022 and the third tranche of $ 25.0 million remains available at the Company's request subject to Lenders' discretion (see Note 6) . Based on the Company’s current financial position and business plan, management believes that its existing cash, cash equivalents and short-term investments will be sufficient to fund the Company’s planned operations for at least twelve months from the issuance date of these consolidated financial statements. Viracta uses third party contract labs and facilities for the manufacture and testing of drug substance, drug product, and clinical trial material while providing internal oversight on technical development, quality and regulatory compliance. This outsourcing model allows Viracta to maintain a flexible infrastructure and capital efficiency while focusing its expertise on developing its products. For the year ended December 31, 2022, the Company had two contract labs that provided 23.2 % of total third-party services. For the year ended December 31, 2021, the Company had one contract lab that provided 13.2 % of total third-party services. The COVID-19 pandemic has caused significant business disruption around the globe. The effects of the COVID-19 pandemic continue to rapidly evolve, and the full impact of the COVID-19 pandemic remains highly uncertain and subject to change. The Company has taken certain measures and continues to evaluate other potential measures to mitigate the impact of the COVID-19 pandemic on our clinical trials. The Company does not yet know the full extent of potential delays or impacts on our business, our clinical trials, healthcare systems or the global economy as a whole. These effects could have a material impact on our operations, 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	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation and Principles of Consolidation The accompanying consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries and have been prepared in accordance with GAAP. All intercompany balances and transactions have been eliminated upon consolidation. Use of Estimates The preparation of consolidated 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 consolidated financial statements and the reported amounts of expenses during the reporting period. Actual results could differ materially from those estimates. Short-Term Investments Short-term investments are marketable securities with maturities greater than three months from date of purchase that are specifically identified to fund current operations. These investments are classified as current assets, even though the stated maturity date may be one year or more beyond the current balance sheet date, which reflects management’s intention to use the proceeds from sales of these securities to fund our operations, as necessary. The cost of short-term investments is adjusted for amortization of premiums or accretion of discounts to maturity, and such amortization or accretion is included in interest income. Dividend and interest income is recognized as interest income on the statements of operations and comprehensive loss when earned. Short-term investments are classified as available-for-sale securities and carried at fair value with unrealized gains and non-credit related losses recorded in other comprehensive income (loss) and included as a separate component of stockholders’ equity. Realized gains and losses from the sale of available-for-sale securities are determined on a specific identification basis and included in interest income on the consolidated statements of operations and comprehensive loss. Allowance for Credit Losses For available-for-sale securities in an unrealized loss position, we first assess whether we intend to sell, or if it is more likely than not that we will be required to sell, the security before recovery of its amortized cost basis. If either of the criteria regarding intent or requirement to sell is met, the security’s amortized cost basis is written down to fair value through earnings. For available-for-sale securities that do not meet the aforementioned criteria, we evaluate whether the decline in fair value has resulted from credit losses or other factors. In making this assessment, we consider the severity of the impairment, any changes in interest rates, market conditions, changes to the underlying credit ratings and forecasted recovery, among other factors. The credit-related portion of unrealized losses, and any subsequent improvements, are recorded in interest income through an allowance account. Any impairment that has not been recorded through an allowance for credit losses is included in other comprehensive income (loss) on the statements of operations and comprehensive loss. We elected the practical expedient to exclude the applicable accrued interest from both the fair value and amortized costs basis of our available-for-sale securities for purposes of identifying and measuring an impairment. Accrued interest receivable on available-for-sale securities is recorded within prepaid expenses and other current assets on our consolidated balance sheets. Our accounting policy is to not measure an allowance for credit loss for accrued interest receivable and to write-off any uncollectible accrued interest receivable as a reversal of interest income in a timely manner, which we consider to be in the period in which we determine the accrued interest will not be collected by us. Concentrations of Credit Risk Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents and short-term investments. 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, cash equivalents and short-term investments. 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. Property and Equipment Property and equipment, which consisted of office equipment, were stated at cost and depreciated over the estimated useful lives of the assets (three to five years) using the straight-line method. Leasehold improvements were amortized over the shorter of their estimated useful lives or the lease term. Leases The Company classifies leases as either operating or finance leases at inception and as necessary at modification. Leased assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent its obligation to make lease payments arising from the lease. The Company does not obtain and control its right to use the identified asset until the lease commencement date. Operating leases are included in operating lease right-of-use (“ROU”) assets, and operating lease liabilities on the Company’s balance sheets. Operating lease ROU assets and liabilities are recognized at lease commencement date based on the present value of lease payments over the lease term. When readily determinable, the Company uses the rate implicit in the lease to discount lease payments; however, when the rate is not readily determinable, the Company uses the incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. The incremental borrowing rate is the rate of interest that the Company would have to pay to borrow an amount equal to the lease payments on a collateralized basis over a similar term and in a similar economic environment. The operating lease ROU asset also includes any initial direct costs, lease payments made prior to lease commencement, and lease incentives received. Variable lease payments are expensed as incurred and are not included within the ROU asset and lease liability calculation. The Company’s lease terms are the noncancelable period and may include options to extend the lease when it is reasonably certain that it will exercise that option. Lease cost for lease payments is recognized on a straight-line basis over the lease term. The Company does not separate lease and non-lease components. The Company does not recognize ROU assets and lease liabilities for short-term leases, which have a lease term of twelve months or less and do not include an option to purchase the underlying asset that the Company is reasonably certain to exercise. Lease cost for short-term leases is recognized on a straight-line basis over the lease term. Revenue Recognition Revenue is recognized when control of the promised goods or services is transferred to the Company’s customers in an amount that reflects the consideration the Company expects to receive from its customers in exchange for those goods and services. This process involves identifying the contract with a customer, determining the performance obligations in the contract, determining the transaction price, allocating the contract price to the distinct performance obligations in the contract, and recognizing revenue when or as the Company satisfies the performance obligation(s). At contract inception, the Company assesses the goods and services promised within each contract and assesses whether each promised good or service is distinct and determines that those are performance obligations. A performance obligation is considered distinct from other obligations in a contract when it provides a benefit to the customer either on its own or together with other resources that are readily available to the customer and is separately identified in the contract. The Company considers factors such as the research, manufacturing and commercialization capabilities of the collaboration partner and the availability of the associated expertise in the general marketplace. The Company considers a performance obligation satisfied once the Company has transferred control of a good or service to the customer, meaning the customer has the ability to use and obtain the benefit of the good or service. The Company recognizes revenue for satisfied performance obligations only when the Company determines there are no uncertainties regarding payment terms or transfer of control. Collaborative Arrangements The Company evaluates collaboration arrangements to determine whether units of account within the collaboration arrangement exhibit the characteristics of a vendor and customer relationship. For arrangements and units of account where a customer relationship exists, the Company applies the revenue recognition guidance. The Company enters into collaborative arrangements with partners that may include payment to the Company of one or more of the following: (i) license fees; (ii) payments related to the achievement of developmental, regulatory, or commercial milestones; and (iii) royalties on net sales of licensed products. If a contract has multiple performance obligations, the Company allocates the transaction price to each distinct performance obligation in an amount that reflects the consideration the Company is entitled to receive in exchange for satisfying each distinct performance obligation. For each distinct performance obligation, revenue is recognized when (or as) the Company transfers control of the product or the service applicable to such performance obligation. The Company evaluates each performance obligation to determine if it can be satisfied at a point in time or over time. In addition, variable consideration must be evaluated to determine if it is constrained and, therefore, excluded from the transaction price. License Fees If a license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from upfront fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. Milestone Payments At the inception of each arrangement that includes milestone payments (variable consideration), the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price. If it is probable that a milestone event would occur at the inception of the arrangement, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company’s control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each reporting period, the Company evaluates the probability of achievement of such milestones and any related constraint(s), and if necessary, may adjust the Company’s estimate of the overall transaction price. To date, the Company has not recognized any milestone revenue resulting from its collaborative arrangements. Royalties For arrangements that include sales-based royalties, including milestone payments based on the level of sales, the Company recognizes revenue when the related sales occur. To date, the Company has not recognized any royalty revenue resulting from its collaborative arrangements. Clinical Trial and Contracts Accruals The Company accrues clinical trial costs based on work performed. In determining the amount to accrue, the Company relies on estimates of total costs incurred based on enrollment, the completion of clinical trials and other events. The Company follows this method because it believes reasonably dependable estimates of the costs applicable to various stages of a clinical trial can be made. However, the actual costs and timing of clinical trials are highly uncertain, subject to risks and may change depending on a number of factors. Differences between the actual clinical trial costs and the estimated clinical trial costs that have been accrued in any prior period are recognized in the subsequent period in which the actual costs become known. Historically, estimated accrued expenses have approximated actual expenses incurred; however, material differences could occur in the future. 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, contract manufacturing costs and services performed by clinical research organizations, research institutions, and other outside service providers. The Company makes estimates of its accrued expenses as of each balance sheet date in the consolidated financial statements based on facts and circumstances known to us at that time. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company will adjust the accrual accordingly. This process involves reviewing contracts and purchase orders, reviewing the terms of vendor agreements, communicating with applicable personnel to identify services that have been performed on the Company's behalf and estimating the level of service performed and the associated cost incurred for the services when it has not yet been invoiced or otherwise notified of actual cost. The majority of the Company's service providers invoice monthly in arrears for services performed. Income Taxes Income taxes are accounted for under the asset and liability method. This approach requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of the differences between the tax basis of assets or liabilities and their carrying amounts in the consolidated financial statements using the enacted tax rates and laws that are anticipated to be in effect when the differences are expected to reverse. The Company provides a valuation allowance against net deferred tax assets if it is more likely than not that these items will either expire before the Company is able to realize their benefit or if future deductibility is uncertain. In accordance with the accounting standards for uncertain tax positions, the Company evaluates the recognition threshold and measurement attribute criteria for the financial statement recognition and measurement of tax positions taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more likely than not to be sustained upon examination by taxing authorities. Share-Based Compensation The Company accounts for share-based compensation expense related to stock options granted to employees, members of the board of directors, and outside consultants by estimating the fair value of each stock option on the date of grant or modification date using the Black-Scholes option pricing model. The Company accounts for restricted stock units (“RSUs”) by determining the fair value of each restricted stock unit based on the closing market price of the common stock on the date of grant or modification date. The Company recognizes share-based compensation 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 December 31, 2022 and December 31, 2021. Investments The Company invests in available-for-sale securities consisting of money market funds, commercial paper, corporate debt securities, U.S. Treasury securities and U.S. agency bonds. Available-for-sale securities are classified as either cash, cash equivalents or short-term investments on the Company's consolidated balance sheets. The following table summarizes, by major security type, the Company's cash equivalents and short-term investments that are measured at fair value on a recurring basis, in thousands: December 31, 2022 Maturities Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash equivalents: Money market funds 1 or less $ 15,492 $ — $ — $ 15,492 Total cash equivalents 15,492 — — 15,492 Short-term investments: U.S. Treasury securities 1 or less 19,785 — ( 109 ) 19,676 Commercial paper 1 or less 27,739 — ( 34 ) 27,705 Corporate debt securities 2 or less 1,872 — — 1,872 U.S. Agency bonds 2 or less 5,052 — ( 35 ) 5,017 Total short-term investments 54,448 — ( 178 ) 54,270 Total $ 69,940 $ — $ ( 178 ) $ 69,762 The Company has classified investments with remaining maturity at purchase of more than three months and remaining maturities of one year or less as short-term investments. The Company has also classified investments with remaining maturities of greater than one year as short-term investments, which reflects management's intention to use the proceeds from sales of these securities to fund operations, as necessary. As of December 31, 2022, the unrealized losses for available-for-sale investments were primarily due to changes in interest rates and not due to increased credit risks associated with specific securities. The Company does not currently intend to sell the investments before recovery of their amortized cost basis, which may be at the time of maturity. As of December 31, 2022, no allowance for credit losses was recorded and the Company did not recognize any impairment losses related to investments. As of December 31, 2022, none of the short-term investments were in a continuous unrealized loss position for a period greater than 12 months. Accrued interest receivable on available-for-sale securities wa s $ 0.1 mi llion at December 31, 2022 . We have no t written off any accrued interest receivables for the year ended December 31, 2022. 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. Available-for-sale securities consist of U.S. Treasury securities, which are measured at fair value using Level 1 inputs and commercial paper, corporate debt securities, and U.S. Agency bonds, which is measured at fair value using Level 2 inputs. The Company determines the fair value of Level 2 related securities with the aid of valuations provided by third parties using proprietary valuation models and analytical tools. These valuation models and analytical tools use market pricing or prices for similar instruments that are both objective and publicly available, including matrix pricing or reported trades, benchmark yields, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids and/or offers. Belo w is a summary of assets, including cash equivalents and short-term investments, measured at fair value as of December 31, 2022, in thousands. Fair Value Measurements Using December 31, 2022 Level 1 Level 2 Cash equivalents: Money market funds $ 15,492 $ 15,492 $ — Total cash equivalents 15,492 15,492 0 Short-term investments: U.S. Treasury securities 19,676 19,676 — Commercial paper 27,705 — 27,705 Corporate debt securities 1,872 — 1,872 U.S. Agency bonds 5,017 — 5,017 Total short-term investments 54,270 19,676 34,594 Total $ 69,762 $ 35,168 $ 34,594 The money market funds, classified as cash equivalents, are Level 1 and had an amortized cost and estimated fair value of $ 14.9 million as of December 31, 2021. The preferred st ock warrant liability, a level 3 fair value measurement, was zero at December 31, 2021, due to the reclassification to equity at the closing of the Merger. The Company had no liabilities measured at fair value on a recurring basis as of December 31, 2022 and December 31, 2021. 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 December 31, 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 outstanding common stock equivalents. For all periods presented, there is no difference in the number of shares used to compute basic and diluted shares outstanding due to the Company's net loss position. The following securities are excluded from the calculation of weighted average dilutive common shares because their inclusion would have been anti-dilutive: December 31, 2022 2021 Shares issuable upon conversion of preferred stock 292,799 292,799 Common stock options and RSUs outstanding 7,751,573 4,797,240 ESPP shares pending issuance 11,718 — Warrants to purchase common stock 23,100 23,100 Total excluded securities 8,079,190 5,113,139 Recently Adopted 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 has adopted this pronouncement in the third quarter of 2022 with no material impact on its consolidated financial statements. Recently Issued Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board or other standard setting bodies that the Company will adopt as of the specified effective date. The Company has evaluated recently issued accounting pronouncements and as a result, based on the Company's preliminary assessment, do not believe any will have a material impact on the consolidated financial statements or related footnote disclosures.

Collaboration and License Agree

Collaboration and License Agreements	12 Months Ended
	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaboration and License Agreements	3. Collaboration and License Agreements Shenzhen Salubris Pharmaceuticals Co. Ltd. License Agreement On November 30, 2018, the Company entered into a License Agreement (the “Salubris Agreement”) with Shenzhen Salubris Pharmaceutical Co. Ltd., (“Salubris”), pursuant to which the Company granted an exclusive, royalty-bearing license, with the right to grant sublicenses to Salubris to research, develop, use, make, have made, sell, offer for sale, have sold, import, and otherwise commercialize nanatinostat in combination with an antiviral drug such as valganciclovir in the Republic of China, excluding Hong Kong, Macau, and Taiwan. On August 19, 2021, the Company, through its wholly-owned subsidiary, Viracta Subsidiary, Inc., entered into a Mutual Termination Agreement with Salubris, effective August 20, 2021 (the “Termination Agreement”), pursuant to which the parties agreed to terminate the Salubris Agreement. Under the terms of the Termination Agreement, the Company paid Salubris a payment in the amount of $ 4.0 million on the effective date of the Termination Agreement, and all licenses granted by the Company to Salubris automatically terminated. The Company recorded the $ 4.0 million payment as purchased and acquired in-process research and development in the statement of operations and comprehensive loss for the year ended December 31, 2021. ImmunityBio License Agreement On May 1, 2017, the Company entered into a License Agreement (the “NK Agreement”) with ImmunityBio, Inc., formerly NantKwest, Inc. (“ImmunityBio”) whereby the Company granted an exclusive worldwide license to ImmunityBio and its affiliates to develop and commercialize nanatinostat for use in combination with NK cell immunotherapies. ImmunityBio will be responsible for conducting all necessary studies, including safety studies and clinical trials necessary in connection with seeking regulatory approvals to market the product in any territory. If ImmunityBio requires nanatinostat, the Company has the right to manufacture nanatinostat to be sold as part of a therapeutic product utilizing nanatinostat at a transfer price related to Viracta’s cost to ImmunityBio. In accordance with the NK Agreement, the Company is also eligible to receive up to a total of $ 100.0 million in milestone payments, with respect to the licensed products. The Company is eligible to earn tiered royalties on net sales of licensed products by ImmunityBio, its affiliates or sublicensees, ranging from the low to mid-single digits. The Company has recognized no revenue from milestones (variable consideration), which are fully constrained, or royalties to date. Unless earlier terminated, the NK Agreement will continue until the expiration of all applicable royalty terms on a product-by-product and country-by-country basis. There are no performance, cancellation, termination, or refund provisions in the arrangement that contain material financial consequences to the Company.

Financial Statement Details

Financial Statement Details	12 Months Ended
	Dec. 31, 2022
Financial Statement Details [Abstract]
Financial Statement Details	4. Financial Statement Details Accrued Expenses Accrued expenses consist of the following (in thousands): December 31, December 31, 2022 2021 Accrued payroll and benefits $ 2,961 $ 1,695 Accrued clinical trial and contract expenses 3,562 3,380 Accrued professional services and expenses 385 271 Other accrued expenses 285 456 Total accrued expenses $ 7,193 $ 5,802 Other Income Pursuant to the CARES Act, eligible employers are entitled to a refundable tax credit, the Employee Retention Credit (the "ERC"), equal to 50 % of qualified wages paid to employees between March 13, 2020 and December 31, 2020, up to a maximum of $ 5,000 credit per employee. In December 2020, Congress expanded and amended the CARES Act by enacting Public Law 116-260. Per this amendment to the CARES Act, eligible employers are entitled to a refundable tax credit equal to 70 % of qualified wages paid to employees between January 1, 2021 and June 30, 2021, up to a maximum of $ 10,000 of wages per employee per quarter, with a maximum of $ 7,000 credit per employee per quarter. Congress further extended the ERC with the American Rescue Plan signed into law on March 11, 2021, which extended the credit for the period July 1, 2021 to December 31, 2021. However, on November 15, 2021, the Infrastructure Investment and Jobs Act redacted the credit for the fourth quarter of 2021. For the year ended December 31, 2022, the Company recognized $ 0.8 million in other income for the ERC, after determining that the amount was both estimable and reasonably assured. The corresponding receivable was recorded within other current assets on the Company’s consolidated balance sheet.

XOMA Transaction

XOMA Transaction	12 Months Ended
	Dec. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
XOMA Transaction	5. XOMA Transaction In December 2019, the Company 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 the Company prior to the XOMA Transaction. Also in December 2019, the Company 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. On Marc h 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, and recorded as a gain in the statement of operations and comprehensive loss, 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.

Debt

Debt	12 Months Ended
	Dec. 31, 2022
Debt Disclosure [Abstract]
Debt	6. Debt Loan Agreement On November 4, 2021, the Company entered into a loan and security agreement, as amended August 26, 2022 (the “SVB-Oxford Loan Facility”) with Silicon Valley Bank (“SVB”) and Oxford Finance, LLC for up to $ 50.0 million. In connection with entering into the SVB-Oxford Loan Facility, the Company and SVB agreed to terminate the Company’s prior $ 15.0 million loan and security agreement with SVB. The existing $ 5.0 million debt balance from the Company’s previous credit facility with SVB was replaced under this SVB-Oxford Loan Facility. The SVB-Oxford Loan Facility was accounted for as a modification based on the effect of changes in terms from the original SVB loan agreement. Under the terms of the SVB-Oxford Loan Facility, the remaining $ 45.0 million was available in two additional tranches of $ 20.0 million and $ 25.0 million under certain circumstances, and the Company was under no obligation to draw funds in the future. The second tranche of $20.0 million was drawn by the Company on December 29, 2022. The third tranche of $25.0 million remains available at the Company's request subject to the Lenders' discretion. The loan will be due on the scheduled maturity date of November 1, 2026 (the “Maturity Date”). In accordance with the original terms of the SVB-Oxford Loan Facility, repayment of the loan is interest only through December 31, 2023, and if evidence of positive Phase 1(b) data in the EBV + solid tumor trial sufficient to advance into Phase 2 is delivered to the Lenders and confirmed by the Company's board of directors prior to December 31, 2023 (the “Milestone”), the interest-only period would be extended through December 31, 2024. This period of interest only will be followed by 35 equal monthly payments of principal plus accrued interest commencing on January 1, 2024, or if the Milestone is achieved, the period of interest only will be followed by 23 equal monthly payments of principal plus accrued interest commencing on January 1, 2025. The per annum interest rate for any outstanding loan is equal to the greater of (i) 8.15 % and (ii) the sum of (a) the Prime Rate, as reported in The Wall Street Journal on the last business day of the month that immediately precedes the month in which the interest will accrue, plus (b) 4.90 %. As of December 31, 2022, the per annum interest rate was 11.90 % . In addition, a final payment of 5.0 % 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-Oxford Loan Facility. The Company’s obligations under the SVB-Oxford Loan Facility are secured by a first priority security interest in substantially all of its current and future assets, other than the Company's intellectual property. The Company has also agreed not to encumber its intellectual property assets, except as permitted by the SVB-Oxford Loan Facility. The SVB-Oxford Loan Facility 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-Oxford Loan Facility 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-Oxford Loan Facility, 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-Oxford Loan Facility. As of December 31, 2022, the Company was in compliance with all financial covenants under the SVB-Oxford Loan Facility and there had been no material adverse change. The debt issuance costs 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 December 31, 2022. The following table summarizes future principal payments (in thousands) under the terms of the SVB-Oxford Loan Facility: Years Ending December 31, 2023 $ — 2024 8,571 2025 8,571 2026 7,858 Thereafter — Total future principal payments 25,000 Unamortized discount ( 123 ) Total, net $ 24,877 Paycheck Protection Program Loan On April 24, 2020, Viracta received loan proceeds of $ 0.3 million 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 $ 0.3 million, 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 for the year ended December 31, 2021.

Merger

Merger	12 Months Ended
	Dec. 31, 2022
Business Combinations [Abstract]
Merger	7. 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 consolidated statements of operations for the year ended December 31, 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 $ 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	12 Months Ended
	Dec. 31, 2022
Stockholders' Equity Note [Abstract]
Stockholders' Equity	8. Stockholders’ Equity Common Stock The total number of shares of common stock of Viracta outstanding as of December 31, 2022 and December 31, 2021 was 38,345,140 and 37,424,863 , 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 $ 50.0 million 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). During the year ended December 31, 2022, the Company sold 564,125 shares of its common stock pursuant to the Sales Agreement at a weighted average price per share of $ 4.26 for $ 2.3 million, net of commissions. 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. 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 December 31, 2022 and 2021, of which 1,915 shares were Series E Stock and 8,333 sh ares 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 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 was $ 0.09 per share. Unless previously exercised, the Common Warrants will expire on the seven-year anniversary of the date of issuance. As of December 31, 2022, Common Warrants to purchase 86,209 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 years ended December 31, 2022 and 2021, as their exercise price is for nominal consideration. In July 2020, the Company issued warrants exercisable for 206,440 pre-merger shares of Series E preferred stock, at a pre-merger 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: December 31, December 31, 2022 2021 Conversion of preferred stock 292,799 292,799 Common stock warrants 109,309 109,309 Stock options issued and outstanding for all plans 7,268,291 4,051,572 RSUs outstanding 483,282 745,668 Authorized for future option grants 1,114,248 1,169,523 Common stock authorized for the ESPP 449,671 60,948 Total 9,717,600 6,429,819 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 December 31, 2022, 67,540 fully vested options remain outstanding under the Sunesis 2011 Plan with a weighted average exercise price of $ 30.22 per share. The share-based compensation recorded in the accompanying consolidated statements of operations for the years ended December 31, 2022 and 2021 is presented below (in thousands): Year Ended December 31, 2022 2021 Research and development $ 2,782 $ 2,122 General and administrative 10,766 3,420 Total $ 13,548 $ 5,542 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. In September 2022, the Board of Directors approved an increase to the 2021 Inducement Plan by 1,375,000 shares, resulting in a new authorized total of 2,375,000 shares of common stock. As of December 31, 2022, there were 235,000 shares available for issuance under the 2021 Inducement Plan. Stock Options The Company recorded share-based compensation related to stock options of $ 11.2 mi llion and $ 4.8 million for the years ended December 31, 2022 and 2021, respectively. Share-based compensation related to stock options for the year ended December 31, 2022 , included a $ 4.0 million non-recurring, non-cash expense associated with modifications to certain stock awards pursuant to the terms of a separation agreement with the Company’s former Chief Executive Officer in September 2022. Fair value is determined on the date of grant for options. Compensation expense is recognized over the requisite service 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, excluding the former Chief Executive Officer option modifications: Year Ended December 31, 2022 2021 Risk free interest rate 1.82 % - 3.97 % 0.66 % - 1.33 % Expected option term 5.5 - 6.3 years 5.8 - 6.3 years Expected volatility of common stock 82.7 % - 86.2 % 84.15 % - 90.2 % Expected dividend yield 0.0 % 0.0 % The fair value of the former Chief Executive Officer option modifications was estimated using the Black-Scholes model with the assumptions disclosed in the following table: Risk free interest rate 3.63 % - 3.82 % Expected option term 3.6 - 6 years Expected volatility of common stock 85.2 % - 91.4 % Expected dividend yield 0.0 % Due to the Company's limited historical exercise behavior, the expected term of stock option grants is based on the simplified method, which is an average of the contractual term of the option and its vesting period. The expected term of the option modification was determined as the average between the remaining vesting period and the remaining contractual life of the options. 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 December 31, 2022, unrecognized compensation expense related to unvested options granted totaled $ 16.2 million. The expense is expected to be recognized over a weighted-average period of 2.8 years. A summary of the stock option activity under the 2016 Plan and the 2021 Plan during the period ended December 31, 2022 is presented below (in thousands except for per share and weighted average term): Number of Weighted Weighted Aggregate Intrinsic Value Outstanding at December 31, 2021 3,964 $ 7.33 8.9 $ 1,973 Granted 3,882 $ 3.79 Exercised ( 105 ) $ 1.24 $ — Cancelled ( 540 ) $ 6.54 Outstanding at December 31, 2022 7,201 $ 5.57 8.8 $ 208 Outstanding at December 31, 2022 (Sunesis 2011 Plan) 67 $ 30.22 3.0 $ — Vested and exercisable at December 31, 2022 2,247 $ 6.80 7.9 $ 168 Outstanding and expected to vest as of December 31, 2022 7,201 $ 5.57 8.8 $ 208 Aggregate intrinsic values are based upon a common stock price of $ 1.46 and $ 3.65 at December 31, 2022 and 2021, respectively, and the contractual exercise price on a pre-tax basis. The weighted average grant date fair value per share of employee stock options granted during the years ended December 31, 2022 and 2021 was $ 2.80 and $ 6.25 , respectively. Restricted Stock Units The Company recorded share-based compensation related to RSUs of $ 2.2 million and $ 0.7 million for the years ended December 31, 2022 and 2021 , respectively. Share-based compensation related to RSUs for the year ended December 31, 2022, included a $ 1.6 million non-recurring, non-cash expense associated with modifications to certain RSUs pursuant to the terms of a separation agreement with the Company’s former Chief Executive Officer in September 2022. The closing stock price on the modification date was used to estimate the fair value of the former Chief Executive Officer's unvested RSUs. For RSU equity awards, the grant date fair value is estimated using the closing stock price on the date of grant. Compensation expense is recognized over the requisite service period based on the fair value of the RSUs. A summary of the restricted stock unit activity under the plans during the period ended December 31, 2022 is presented below (in thousands except for per share and weighted average term): RSUs Weighted Weighted Outstanding at December 31, 2021 745 $ 4.22 3.4 Granted — — Vested ( 198 ) $ 3.94 Cancelled ( 64 ) $ 8.01 Outstanding at December 31, 2022 483 $ 3.83 1.3 As of December 31, 2022, unrecognized compensation expense related to unvested RSUs totaled $ 0.6 million. The expense is expected to be recognized over a weighted-average period of 2.4 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. No shares were purchased under the 2011 ESPP for the year ending December 31, 2021. In June 2022, the Company adopted the 2022 Employee Stock Purchase Plan (the “2022 ESPP”). The 2022 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 6-month offering period, or (ii) at the end of the 6-month offering period. No participant in the 2022 ESPP may be issued or transferred shares of common stock valued at more than $ 25,000 per calendar year. In conjunction with the adoption of the 2022 ESPP, the previous 2011 Employee Stock Purchase Plan was terminated. As of December 31, 2022 , there were 50,329 shares issued, and 449,671 shares are available for future issuance under the 2022 ESPP. The Company recorded share-based compensation related to the 2022 ESPP of $ 0.1 million for the year ended December 31, 2022. There was no expense the year ended December 31, 2021.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Leases In June 2020, the Company amended the existing office leases to enter into a noncancelable operating lease to extend the lease terms 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 right-of-use (“ROU”) asset and corresponding lease liability for $ 0.7 million. 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 $ 0.4 million. The following table summarizes future minimum payments under the Company's operating leases as of December 31, 2022 (in thousands): Years Ending December 31, 2023 $ 284 Thereafter — Total lease payments 284 Less: imputed interest ( 6 ) Total operating lease liabilities $ 278 Total lease expense for the years ended December 31, 2022 and 2021 was $ 0.4 million and $ 0.6 million, respectively. At December 31, 2022, the Company had remaining current lease liabilities of approximately $ 0.3 and operating lease ROU assets of $ 0.3 . Other supplemental cash flow information consisted of the following: Year Ended 2022 2021 Cash paid for amounts included in the measurement of operating lease liabilities $ 0.4 $ 0.5 Other supplemental information, as of December 31, 2022, consisted of the following: 2022 Weighted-average discount rate 8.0 % Weighted-average remaining lease term (in years) 0.7 There were no new or amended lease arrangements executed in 2022 or 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.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Income Taxes	10. Income Taxes As a result of the Company’s significant operating loss carryforwards and the corresponding valuation allowance, no income tax provision/benefit has been recorded as of December 31, 2022 and 2021. Significant components of the Company’s deferred tax assets and liabilities as of December 31, 2022 and 2021 are detailed below (in thousands). Year Ended December 31, 2022 2021 Deferred tax assets: Federal and state net operating loss carryforwards $ 41,179 $ 37,319 Federal and California research and development credit carryforwards 9,058 6,674 Share-based compensation expense 1,899 701 Capitalized 59(e) Expenses and Amortization 3,829 4,804 Section 174 Capitalized R&D Expenditures 4,768 — Other, net 52 107 Total deferred tax assets 60,785 49,605 ROU asset ( 56 ) ( 134 ) Total deferred tax liabilities ( 56 ) ( 134 ) Net deferred tax asset 60,729 49,471 Valuation allowance ( 60,729 ) ( 49,471 ) Net deferred tax liability $ — $ — The Company’s effective income tax rate differs from the statutory federal rate of 21 % for the years ended December 31, 2022 and 2021 due to the following: Year Ended December 31, 2022 2021 % % Federal statutory rate 21 21 State tax benefit, net of federal benefit — 7 Valuation allowance ( 23 ) ( 9 ) General business credits 5 3 Acquired IPR&D — ( 21 ) Other ( 3 ) ( 1 ) Effective income tax rate — — At December 31, 2022, the Company had federal and state net operating loss carryforwards o f $ 165.5 million and $ 106.6 m illion, respectively. The federal loss carryforwards begin to expire in 2027 , unless previously utilized, and the state carryforwards begin to expire in 2030 . Included in the federal loss carryforwards are $ 125.2 millio n of losses that are not subject to expiration. The Company also has federal and state research credit carryforwards o f $ 1.5 million and $ 2.3 million, re spectively. Additionally the Company has Orphan Drug Credit carryforwards of $ 10.1 million. The federal research credit carryforwards will begin expiring in 2027 , unless previously utilized. The state research credit will carry forward indefinitely. The change in the valuation allowance is an increase of $ 11.3 million and $ 24.6 million for the years ended December 31, 2022 and December 31, 2021, respectively. Pursuant to Internal Revenue Code (“IRC”) Sections 382 and 383, annual use of the Company’s net operating loss and research and development credit carryforwards may be limited in the event a cumulative change in ownership of more than 50% occurs within a three-year period. The Company has not completed an IRC Section 382/383 analysis regarding the limitation of net operating loss and research and development credit carryforwards. Due to the existence of the valuation allowance, future changes in the Company’s unrecognized tax benefits will not impact the Company’s effective tax rate. The Company’s ability to use its remaining net operating loss and tax credit carryforwards may be further limited if the Company experiences a Section 382 ownership change in connection with future changes in its stock ownership. In accordance with authoritative guidance, the impact of an uncertain income tax position is recognized at the largest amount that is “more likely than not” to be sustained upon audit by the relevant taxing authority. An uncertain tax position will not be recognized if it has less than a 50% likelihood of being sustained. The following table summarizes the activity related to the Company’s unrecognized tax benefits (in thousands): Year Ended December 31, 2022 2021 Gross unrecognized tax benefits at the beginning of the year $ 4,962 $ 3,971 Additions based on tax positions related to the current year 884 991 Reductions for tax positions of prior years ( 65 ) — Gross unrecognized tax benefits at the end of the year $ 5,781 $ 4,962 The Company does not expect that the unrecognized tax benefits will change within 12 months of this reporting date. Due to the existence of the valuation allowance, future changes in the Company’s unrecognized tax benefits will not impact the Company’s effective tax rate. The Company’s policy is to recognize interest and penalties related to income tax matters in income tax expense. For the year ended December 31, 2022, the Company has not recognized any interest or penalties related to income taxes. The Company is subject to taxation in the U.S. and California. Due to the existence of net operating loss carryforwards, all tax periods from inception of the Company are open for examination by taxing authorities for all jurisdictions. The Company is not currently under examination by any tax authority.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2022
Subsequent Events [Abstract]
Subsequent Events	11. Subsequent Events On March 10, 2023, SVB was closed by the California Department of Financial Protection and Innovation, which appointed the Federal Deposit Insurance Corporation, or the FDIC, as receiver. The Company has been informed by the Lenders under its SVB-Oxford Loan Facility that the future tranche under the loan facility remains available subject to the Lenders’ discretion on the same terms as set forth in the SVB-Oxford Loan Facility. As of the date of filing this Annual Report on Form 10-K, the Company has full access to and control over all its cash, cash equivalents and short-term investments.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The accompanying consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries and have been prepared in accordance with GAAP. All intercompany balances and transactions have been eliminated upon consolidation.
Use of Estimates	Use of Estimates The preparation of consolidated 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 consolidated financial statements and the reported amounts of expenses during the reporting period. Actual results could differ materially from those estimates.
Short-Term Investments	Short-Term Investments Short-term investments are marketable securities with maturities greater than three months from date of purchase that are specifically identified to fund current operations. These investments are classified as current assets, even though the stated maturity date may be one year or more beyond the current balance sheet date, which reflects management’s intention to use the proceeds from sales of these securities to fund our operations, as necessary. The cost of short-term investments is adjusted for amortization of premiums or accretion of discounts to maturity, and such amortization or accretion is included in interest income. Dividend and interest income is recognized as interest income on the statements of operations and comprehensive loss when earned. Short-term investments are classified as available-for-sale securities and carried at fair value with unrealized gains and non-credit related losses recorded in other comprehensive income (loss) and included as a separate component of stockholders’ equity. Realized gains and losses from the sale of available-for-sale securities are determined on a specific identification basis and included in interest income on the consolidated statements of operations and comprehensive loss.
Allowance for Credit Losses	Allowance for Credit Losses For available-for-sale securities in an unrealized loss position, we first assess whether we intend to sell, or if it is more likely than not that we will be required to sell, the security before recovery of its amortized cost basis. If either of the criteria regarding intent or requirement to sell is met, the security’s amortized cost basis is written down to fair value through earnings. For available-for-sale securities that do not meet the aforementioned criteria, we evaluate whether the decline in fair value has resulted from credit losses or other factors. In making this assessment, we consider the severity of the impairment, any changes in interest rates, market conditions, changes to the underlying credit ratings and forecasted recovery, among other factors. The credit-related portion of unrealized losses, and any subsequent improvements, are recorded in interest income through an allowance account. Any impairment that has not been recorded through an allowance for credit losses is included in other comprehensive income (loss) on the statements of operations and comprehensive loss. We elected the practical expedient to exclude the applicable accrued interest from both the fair value and amortized costs basis of our available-for-sale securities for purposes of identifying and measuring an impairment. Accrued interest receivable on available-for-sale securities is recorded within prepaid expenses and other current assets on our consolidated balance sheets. Our accounting policy is to not measure an allowance for credit loss for accrued interest receivable and to write-off any uncollectible accrued interest receivable as a reversal of interest income in a timely manner, which we consider to be in the period in which we determine the accrued interest will not be collected by us.
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, cash equivalents and short-term investments. 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, cash equivalents and short-term investments.
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.
Property and Equipment	Property and Equipment Property and equipment, which consisted of office equipment, were stated at cost and depreciated over the estimated useful lives of the assets (three to five years) using the straight-line method. Leasehold improvements were amortized over the shorter of their estimated useful lives or the lease term.
Leases	Leases The Company classifies leases as either operating or finance leases at inception and as necessary at modification. Leased assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent its obligation to make lease payments arising from the lease. The Company does not obtain and control its right to use the identified asset until the lease commencement date. Operating leases are included in operating lease right-of-use (“ROU”) assets, and operating lease liabilities on the Company’s balance sheets. Operating lease ROU assets and liabilities are recognized at lease commencement date based on the present value of lease payments over the lease term. When readily determinable, the Company uses the rate implicit in the lease to discount lease payments; however, when the rate is not readily determinable, the Company uses the incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. The incremental borrowing rate is the rate of interest that the Company would have to pay to borrow an amount equal to the lease payments on a collateralized basis over a similar term and in a similar economic environment. The operating lease ROU asset also includes any initial direct costs, lease payments made prior to lease commencement, and lease incentives received. Variable lease payments are expensed as incurred and are not included within the ROU asset and lease liability calculation. The Company’s lease terms are the noncancelable period and may include options to extend the lease when it is reasonably certain that it will exercise that option. Lease cost for lease payments is recognized on a straight-line basis over the lease term. The Company does not separate lease and non-lease components. The Company does not recognize ROU assets and lease liabilities for short-term leases, which have a lease term of twelve months or less and do not include an option to purchase the underlying asset that the Company is reasonably certain to exercise. Lease cost for short-term leases is recognized on a straight-line basis over the lease term.
Revenue Recognition	Revenue Recognition Revenue is recognized when control of the promised goods or services is transferred to the Company’s customers in an amount that reflects the consideration the Company expects to receive from its customers in exchange for those goods and services. This process involves identifying the contract with a customer, determining the performance obligations in the contract, determining the transaction price, allocating the contract price to the distinct performance obligations in the contract, and recognizing revenue when or as the Company satisfies the performance obligation(s). At contract inception, the Company assesses the goods and services promised within each contract and assesses whether each promised good or service is distinct and determines that those are performance obligations. A performance obligation is considered distinct from other obligations in a contract when it provides a benefit to the customer either on its own or together with other resources that are readily available to the customer and is separately identified in the contract. The Company considers factors such as the research, manufacturing and commercialization capabilities of the collaboration partner and the availability of the associated expertise in the general marketplace. The Company considers a performance obligation satisfied once the Company has transferred control of a good or service to the customer, meaning the customer has the ability to use and obtain the benefit of the good or service. The Company recognizes revenue for satisfied performance obligations only when the Company determines there are no uncertainties regarding payment terms or transfer of control. Collaborative Arrangements The Company evaluates collaboration arrangements to determine whether units of account within the collaboration arrangement exhibit the characteristics of a vendor and customer relationship. For arrangements and units of account where a customer relationship exists, the Company applies the revenue recognition guidance. The Company enters into collaborative arrangements with partners that may include payment to the Company of one or more of the following: (i) license fees; (ii) payments related to the achievement of developmental, regulatory, or commercial milestones; and (iii) royalties on net sales of licensed products. If a contract has multiple performance obligations, the Company allocates the transaction price to each distinct performance obligation in an amount that reflects the consideration the Company is entitled to receive in exchange for satisfying each distinct performance obligation. For each distinct performance obligation, revenue is recognized when (or as) the Company transfers control of the product or the service applicable to such performance obligation. The Company evaluates each performance obligation to determine if it can be satisfied at a point in time or over time. In addition, variable consideration must be evaluated to determine if it is constrained and, therefore, excluded from the transaction price. License Fees If a license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from upfront fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. Milestone Payments At the inception of each arrangement that includes milestone payments (variable consideration), the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price. If it is probable that a milestone event would occur at the inception of the arrangement, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company’s control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each reporting period, the Company evaluates the probability of achievement of such milestones and any related constraint(s), and if necessary, may adjust the Company’s estimate of the overall transaction price. To date, the Company has not recognized any milestone revenue resulting from its collaborative arrangements. Royalties For arrangements that include sales-based royalties, including milestone payments based on the level of sales, the Company recognizes revenue when the related sales occur. To date, the Company has not recognized any royalty revenue resulting from its collaborative arrangements.
Clinical Trial and Contracts Accruals	Clinical Trial and Contracts Accruals The Company accrues clinical trial costs based on work performed. In determining the amount to accrue, the Company relies on estimates of total costs incurred based on enrollment, the completion of clinical trials and other events. The Company follows this method because it believes reasonably dependable estimates of the costs applicable to various stages of a clinical trial can be made. However, the actual costs and timing of clinical trials are highly uncertain, subject to risks and may change depending on a number of factors. Differences between the actual clinical trial costs and the estimated clinical trial costs that have been accrued in any prior period are recognized in the subsequent period in which the actual costs become known. Historically, estimated accrued expenses have approximated actual expenses incurred; however, material differences could occur in the future.
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, contract manufacturing costs and services performed by clinical research organizations, research institutions, and other outside service providers. The Company makes estimates of its accrued expenses as of each balance sheet date in the consolidated financial statements based on facts and circumstances known to us at that time. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company will adjust the accrual accordingly. This process involves reviewing contracts and purchase orders, reviewing the terms of vendor agreements, communicating with applicable personnel to identify services that have been performed on the Company's behalf and estimating the level of service performed and the associated cost incurred for the services when it has not yet been invoiced or otherwise notified of actual cost. The majority of the Company's service providers invoice monthly in arrears for services performed.
Income Taxes	Income Taxes Income taxes are accounted for under the asset and liability method. This approach requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of the differences between the tax basis of assets or liabilities and their carrying amounts in the consolidated financial statements using the enacted tax rates and laws that are anticipated to be in effect when the differences are expected to reverse. The Company provides a valuation allowance against net deferred tax assets if it is more likely than not that these items will either expire before the Company is able to realize their benefit or if future deductibility is uncertain. In accordance with the accounting standards for uncertain tax positions, the Company evaluates the recognition threshold and measurement attribute criteria for the financial statement recognition and measurement of tax positions taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more likely than not to be sustained upon examination by taxing authorities.
Share-Based Compensation	Share-Based Compensation The Company accounts for share-based compensation expense related to stock options granted to employees, members of the board of directors, and outside consultants by estimating the fair value of each stock option on the date of grant or modification date using the Black-Scholes option pricing model. The Company accounts for restricted stock units (“RSUs”) by determining the fair value of each restricted stock unit based on the closing market price of the common stock on the date of grant or modification date. The Company recognizes share-based compensation 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 December 31, 2022 and December 31, 2021.
Investments	Investments The Company invests in available-for-sale securities consisting of money market funds, commercial paper, corporate debt securities, U.S. Treasury securities and U.S. agency bonds. Available-for-sale securities are classified as either cash, cash equivalents or short-term investments on the Company's consolidated balance sheets. The following table summarizes, by major security type, the Company's cash equivalents and short-term investments that are measured at fair value on a recurring basis, in thousands: December 31, 2022 Maturities Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash equivalents: Money market funds 1 or less $ 15,492 $ — $ — $ 15,492 Total cash equivalents 15,492 — — 15,492 Short-term investments: U.S. Treasury securities 1 or less 19,785 — ( 109 ) 19,676 Commercial paper 1 or less 27,739 — ( 34 ) 27,705 Corporate debt securities 2 or less 1,872 — — 1,872 U.S. Agency bonds 2 or less 5,052 — ( 35 ) 5,017 Total short-term investments 54,448 — ( 178 ) 54,270 Total $ 69,940 $ — $ ( 178 ) $ 69,762 The Company has classified investments with remaining maturity at purchase of more than three months and remaining maturities of one year or less as short-term investments. The Company has also classified investments with remaining maturities of greater than one year as short-term investments, which reflects management's intention to use the proceeds from sales of these securities to fund operations, as necessary. As of December 31, 2022, the unrealized losses for available-for-sale investments were primarily due to changes in interest rates and not due to increased credit risks associated with specific securities. The Company does not currently intend to sell the investments before recovery of their amortized cost basis, which may be at the time of maturity. As of December 31, 2022, no allowance for credit losses was recorded and the Company did not recognize any impairment losses related to investments. As of December 31, 2022, none of the short-term investments were in a continuous unrealized loss position for a period greater than 12 months. Accrued interest receivable on available-for-sale securities wa s $ 0.1 mi llion at December 31, 2022 . We have no t written off any accrued interest receivables for the year ended December 31, 2022.
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. Available-for-sale securities consist of U.S. Treasury securities, which are measured at fair value using Level 1 inputs and commercial paper, corporate debt securities, and U.S. Agency bonds, which is measured at fair value using Level 2 inputs. The Company determines the fair value of Level 2 related securities with the aid of valuations provided by third parties using proprietary valuation models and analytical tools. These valuation models and analytical tools use market pricing or prices for similar instruments that are both objective and publicly available, including matrix pricing or reported trades, benchmark yields, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids and/or offers. Belo w is a summary of assets, including cash equivalents and short-term investments, measured at fair value as of December 31, 2022, in thousands. Fair Value Measurements Using December 31, 2022 Level 1 Level 2 Cash equivalents: Money market funds $ 15,492 $ 15,492 $ — Total cash equivalents 15,492 15,492 0 Short-term investments: U.S. Treasury securities 19,676 19,676 — Commercial paper 27,705 — 27,705 Corporate debt securities 1,872 — 1,872 U.S. Agency bonds 5,017 — 5,017 Total short-term investments 54,270 19,676 34,594 Total $ 69,762 $ 35,168 $ 34,594 The money market funds, classified as cash equivalents, are Level 1 and had an amortized cost and estimated fair value of $ 14.9 million as of December 31, 2021. The preferred st ock warrant liability, a level 3 fair value measurement, was zero at December 31, 2021, due to the reclassification to equity at the closing of the Merger. The Company had no liabilities measured at fair value on a recurring basis as of December 31, 2022 and December 31, 2021.
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 December 31, 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 outstanding common stock equivalents. For all periods presented, there is no difference in the number of shares used to compute basic and diluted shares outstanding due to the Company's net loss position. The following securities are excluded from the calculation of weighted average dilutive common shares because their inclusion would have been anti-dilutive: December 31, 2022 2021 Shares issuable upon conversion of preferred stock 292,799 292,799 Common stock options and RSUs outstanding 7,751,573 4,797,240 ESPP shares pending issuance 11,718 — Warrants to purchase common stock 23,100 23,100 Total excluded securities 8,079,190 5,113,139
Recently Accounting Pronouncements	Recently Adopted 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 has adopted this pronouncement in the third quarter of 2022 with no material impact on its consolidated financial statements. Recently Issued Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board or other standard setting bodies that the Company will adopt as of the specified effective date. The Company has evaluated recently issued accounting pronouncements and as a result, based on the Company's preliminary assessment, do not believe any will have a material impact on the consolidated financial statements or related footnote disclosures.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Summary of short-term investments measured at fair value on a recurring basis	The following table summarizes, by major security type, the Company's cash equivalents and short-term investments that are measured at fair value on a recurring basis, in thousands: December 31, 2022 Maturities Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash equivalents: Money market funds 1 or less $ 15,492 $ — $ — $ 15,492 Total cash equivalents 15,492 — — 15,492 Short-term investments: U.S. Treasury securities 1 or less 19,785 — ( 109 ) 19,676 Commercial paper 1 or less 27,739 — ( 34 ) 27,705 Corporate debt securities 2 or less 1,872 — — 1,872 U.S. Agency bonds 2 or less 5,052 — ( 35 ) 5,017 Total short-term investments 54,448 — ( 178 ) 54,270 Total $ 69,940 $ — $ ( 178 ) $ 69,762
Summary of assets including cash equivalents and marketable securities, measured at fair value	Belo w is a summary of assets, including cash equivalents and short-term investments, measured at fair value as of December 31, 2022, in thousands. Fair Value Measurements Using December 31, 2022 Level 1 Level 2 Cash equivalents: Money market funds $ 15,492 $ 15,492 $ — Total cash equivalents 15,492 15,492 0 Short-term investments: U.S. Treasury securities 19,676 19,676 — Commercial paper 27,705 — 27,705 Corporate debt securities 1,872 — 1,872 U.S. Agency bonds 5,017 — 5,017 Total short-term investments 54,270 19,676 34,594 Total $ 69,762 $ 35,168 $ 34,594
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 December 31, 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: December 31, 2022 2021 Shares issuable upon conversion of preferred stock 292,799 292,799 Common stock options and RSUs outstanding 7,751,573 4,797,240 ESPP shares pending issuance 11,718 — Warrants to purchase common stock 23,100 23,100 Total excluded securities 8,079,190 5,113,139

Financial Statement Details (Ta

Financial Statement Details (Tables)	12 Months Ended
	Dec. 31, 2022
Financial Statement Details [Abstract]
Schedule of Accrued Liabilities	Accrued expenses consist of the following (in thousands): December 31, December 31, 2022 2021 Accrued payroll and benefits $ 2,961 $ 1,695 Accrued clinical trial and contract expenses 3,562 3,380 Accrued professional services and expenses 385 271 Other accrued expenses 285 456 Total accrued expenses $ 7,193 $ 5,802

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2022
Debt Disclosure [Abstract]
Summary of Future Minimum Payments Under Loan Facility	The following table summarizes future principal payments (in thousands) under the terms of the SVB-Oxford Loan Facility: Years Ending December 31, 2023 $ — 2024 8,571 2025 8,571 2026 7,858 Thereafter — Total future principal payments 25,000 Unamortized discount ( 123 ) Total, net $ 24,877

Merger (Tables)

Merger (Tables)	12 Months Ended
	Dec. 31, 2022
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)	12 Months Ended
	Dec. 31, 2022
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: December 31, December 31, 2022 2021 Conversion of preferred stock 292,799 292,799 Common stock warrants 109,309 109,309 Stock options issued and outstanding for all plans 7,268,291 4,051,572 RSUs outstanding 483,282 745,668 Authorized for future option grants 1,114,248 1,169,523 Common stock authorized for the ESPP 449,671 60,948 Total 9,717,600 6,429,819
Summary of Shared Based Compensation Cost Included in Consolidated Statement of Operations	The share-based compensation recorded in the accompanying consolidated statements of operations for the years ended December 31, 2022 and 2021 is presented below (in thousands): Year Ended December 31, 2022 2021 Research and development $ 2,782 $ 2,122 General and administrative 10,766 3,420 Total $ 13,548 $ 5,542
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, excluding the former Chief Executive Officer option modifications: Year Ended December 31, 2022 2021 Risk free interest rate 1.82 % - 3.97 % 0.66 % - 1.33 % Expected option term 5.5 - 6.3 years 5.8 - 6.3 years Expected volatility of common stock 82.7 % - 86.2 % 84.15 % - 90.2 % Expected dividend yield 0.0 % 0.0 % The fair value of the former Chief Executive Officer option modifications was estimated using the Black-Scholes model with the assumptions disclosed in the following table: Risk free interest rate 3.63 % - 3.82 % Expected option term 3.6 - 6 years Expected volatility of common stock 85.2 % - 91.4 % Expected dividend yield 0.0 %
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 December 31, 2022 is presented below (in thousands except for per share and weighted average term): Number of Weighted Weighted Aggregate Intrinsic Value Outstanding at December 31, 2021 3,964 $ 7.33 8.9 $ 1,973 Granted 3,882 $ 3.79 Exercised ( 105 ) $ 1.24 $ — Cancelled ( 540 ) $ 6.54 Outstanding at December 31, 2022 7,201 $ 5.57 8.8 $ 208 Outstanding at December 31, 2022 (Sunesis 2011 Plan) 67 $ 30.22 3.0 $ — Vested and exercisable at December 31, 2022 2,247 $ 6.80 7.9 $ 168 Outstanding and expected to vest as of December 31, 2022 7,201 $ 5.57 8.8 $ 208 Aggregate intrinsic values are based upon a common stock price of $ 1.46 and $ 3.65 at December 31, 2022 and 2021, respectively, and the contractual exercise price on a pre-tax basis. The weighted average grant date fair value per share of employee stock options granted during the years ended December 31, 2022 and 2021 was $ 2.80 and $ 6.25 , respectively.
Summary of Restricted Stock Units Activity	A summary of the restricted stock unit activity under the plans during the period ended December 31, 2022 is presented below (in thousands except for per share and weighted average term): RSUs Weighted Weighted Outstanding at December 31, 2021 745 $ 4.22 3.4 Granted — — Vested ( 198 ) $ 3.94 Cancelled ( 64 ) $ 8.01 Outstanding at December 31, 2022 483 $ 3.83 1.3

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Future minimum rental payments for operating leases	The following table summarizes future minimum payments under the Company's operating leases as of December 31, 2022 (in thousands): Years Ending December 31, 2023 $ 284 Thereafter — Total lease payments 284 Less: imputed interest ( 6 ) Total operating lease liabilities $ 278
Schedule Of cash flow supplemental disclosures	Other supplemental cash flow information consisted of the following: Year Ended 2022 2021 Cash paid for amounts included in the measurement of operating lease liabilities $ 0.4 $ 0.5 Other supplemental information, as of December 31, 2022, consisted of the following: 2022 Weighted-average discount rate 8.0 % Weighted-average remaining lease term (in years) 0.7

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Schedule of Deferred Tax Assets and Liabilities	Significant components of the Company’s deferred tax assets and liabilities as of December 31, 2022 and 2021 are detailed below (in thousands). Year Ended December 31, 2022 2021 Deferred tax assets: Federal and state net operating loss carryforwards $ 41,179 $ 37,319 Federal and California research and development credit carryforwards 9,058 6,674 Share-based compensation expense 1,899 701 Capitalized 59(e) Expenses and Amortization 3,829 4,804 Section 174 Capitalized R&D Expenditures 4,768 — Other, net 52 107 Total deferred tax assets 60,785 49,605 ROU asset ( 56 ) ( 134 ) Total deferred tax liabilities ( 56 ) ( 134 ) Net deferred tax asset 60,729 49,471 Valuation allowance ( 60,729 ) ( 49,471 ) Net deferred tax liability $ — $ —
Schedule of Effective Income Tax Rate	The Company’s effective income tax rate differs from the statutory federal rate of 21 % for the years ended December 31, 2022 and 2021 due to the following: Year Ended December 31, 2022 2021 % % Federal statutory rate 21 21 State tax benefit, net of federal benefit — 7 Valuation allowance ( 23 ) ( 9 ) General business credits 5 3 Acquired IPR&D — ( 21 ) Other ( 3 ) ( 1 ) Effective income tax rate — —
Schedule of Unrecognized Tax Benefits	The following table summarizes the activity related to the Company’s unrecognized tax benefits (in thousands): Year Ended December 31, 2022 2021 Gross unrecognized tax benefits at the beginning of the year $ 4,962 $ 3,971 Additions based on tax positions related to the current year 884 991 Reductions for tax positions of prior years ( 65 ) — Gross unrecognized tax benefits at the end of the year $ 5,781 $ 4,962

Organization and Basis of Pre_2

Organization and Basis of Presentation - Additional Information (Detail) $ in Thousands			1 Months Ended	12 Months Ended
	Mar. 22, 2021 USD ($)	Feb. 24, 2021	Feb. 28, 2021 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Nov. 04, 2021 USD ($)
Accumulated deficit				$ (214,874)	$ (165,677)
Cash and cash equivalents				36,773	$ 103,554
Working capital				$ 83,700
Gross proceeds from private placement			$ 65,000
Reverse stock split		3.5-for-one
Percentage of outstanding common stock of combined company				86%
Conversion ratio				0.1119
Cash cash equivalents and short term investments				$ 91,000
Line of Credit Facility, Remaining Borrowing Capacity						$ 45,000
Third Party Service Percentage				23.20%	13.20%
Tranche Two [Member]
Line of Credit Facility, Remaining Borrowing Capacity						25,000
Silicon Valley Bank ("SVB") and Oxford Finance LLC ("Oxford") [Member]
Line of credit maximum borrowing amount						50,000
Line of Credit Facility, Current Borrowing Capacity						5,000
Line of Credit Facility, Remaining Borrowing Capacity						45,000
Silicon Valley Bank ("SVB") and Oxford Finance LLC ("Oxford") [Member] | Tranche Two [Member]
Line of Credit Facility, Remaining Borrowing Capacity						20,000
Silicon Valley Bank ("SVB") and Oxford Finance LLC ("Oxford") [Member] | Tranche Three [Member]
Line of Credit Facility, Remaining Borrowing Capacity						$ 25,000
Royalty Purchase Agreement [member]
Upfront payment received	$ 13,500

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Summary of short-term investments measured at fair value on a recurring basis (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, Amortization cost	$ 69,940
Debt securities, Unrealized gains	0
Debt securities, Unrealized losses	(178)
Debt securities	69,762
Cash and Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, Amortization cost	15,492
Debt securities, Unrealized gains	0
Debt securities, Unrealized losses	0
Debt securities	15,492
Cash and Cash Equivalents [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, Amortization cost	15,492
Debt securities, Unrealized gains	0
Debt securities, Unrealized losses	0
Debt securities	15,492
Short-Term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, Amortization cost	54,448
Debt securities, Unrealized gains	0
Debt securities, Unrealized losses	(178)
Debt securities	54,270
Short-Term Investments [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, Amortization cost	27,739
Debt securities, Unrealized gains	0
Debt securities, Unrealized losses	(34)
Debt securities	27,705
Short-Term Investments [Member] | US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, Amortization cost	19,785
Debt securities, Unrealized gains	0
Debt securities, Unrealized losses	(109)
Debt securities	19,676
Short-Term Investments [Member] | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, Amortization cost	1,872
Debt securities, Unrealized gains	0
Debt securities, Unrealized losses	0
Debt securities	1,872
Short-Term Investments [Member] | U.S. Agency bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, Amortization cost	5,052
Debt securities, Unrealized gains	0
Debt securities, Unrealized losses	(35)
Debt securities	$ 5,017

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Summary of assets including cash equivalents and marketable securities, measured at fair value (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	$ 0	$ 0
Cash and Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	15,492
Cash and Cash Equivalents [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	15,492
Cash and Cash Equivalents [Member] | Fair Value Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	15,492
Cash and Cash Equivalents [Member] | Fair Value Level 1 [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	15,492
Cash and Cash Equivalents [Member] | Fair Value Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	0
Cash and Cash Equivalents [Member] | Fair Value Level 2 [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	0
Short-Term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	54,270
Total	69,762
Short-Term Investments [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	27,705
Short-Term Investments [Member] | US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	19,676
Short-Term Investments [Member] | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	1,872
Short-Term Investments [Member] | U.S. Agency bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	5,017
Short-Term Investments [Member] | Fair Value Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	19,676
Total	35,168
Short-Term Investments [Member] | Fair Value Level 1 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	0
Short-Term Investments [Member] | Fair Value Level 1 [Member] | US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	19,676
Short-Term Investments [Member] | Fair Value Level 1 [Member] | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	0
Short-Term Investments [Member] | Fair Value Level 1 [Member] | U.S. Agency bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	0
Short-Term Investments [Member] | Fair Value Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	34,594
Total	34,594
Short-Term Investments [Member] | Fair Value Level 2 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	27,705
Short-Term Investments [Member] | Fair Value Level 2 [Member] | US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	0
Short-Term Investments [Member] | Fair Value Level 2 [Member] | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	1,872
Short-Term Investments [Member] | Fair Value Level 2 [Member] | U.S. Agency bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	$ 5,017

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Summary of Fair Value Measurement Inputs and Valuation Techniques (Detail) - Preferred Stock Warrant Liability [Member]	Feb. 24, 2021 yr UsDollarsShare
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_7

Summary of Significant Accounting Policies - Summary of Reconciliation of Warrant Liability Measured at Fair Value (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Change in fair value of preferred stock warrant liability
Preferred Stock Warrant Liability [Member]
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_8

Summary of Significant Accounting Policies - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) Segment	Dec. 31, 2021 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, Accrued interest receivable	$ 100
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Other Assets, Noncurrent
Assets measured at fair value on recurring basis	$ 0	$ 0
Available-for-sale, Accrued interest writeoff	$ 0
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
Fair Value Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money Market Funds Fair Value		$ 14,900

Summary of Significant Accoun_9

Summary of Significant Accounting Policies - Summary of Antidilutive Securities Excluded From the Calculation of Weighted Average Dilutive Common Shares (Detail) - shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	8,079,190	5,113,139
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	292,799
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	7,751,573	4,797,240
ESPP shares pending issuance [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	11,718	0
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	23,100

Collaboration and License Agr_2

Collaboration and License Agreements - Additional Information (Details) - USD ($)		12 Months Ended
	Aug. 19, 2021	Dec. 31, 2022	Dec. 31, 2021	May 01, 2017
Collaboration and License Agreements [Line Items]
Acquired In Process Research And Development		$ 0	$ 84,478,000
Termination Agreement [Member]
Collaboration and License Agreements [Line Items]
Amount paid on the termination of agreement	$ 4,000,000
Acquired In Process Research And Development			$ 4,000
NK Agreement [Member]
Collaboration and License Agreements [Line Items]
Milestone payments to be received				$ 100,000,000

Financial Statement Details -

Financial Statement Details - Schedule of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Payables and Accruals [Abstract]
Accrued payroll and benefits	$ 2,961	$ 1,695
Accrued clinical trial and contract expenses	3,562	3,380
Accrued professional services and expenses	385	271
Other accrued expenses	285	456
Total accrued expenses	$ 7,193	$ 5,802

Financial Statement Details - A

Financial Statement Details - Additional Information (Detail) - Employee Retention Credit [Member] - USD ($) $ in Thousands	6 Months Ended	10 Months Ended
	Jun. 30, 2021	Dec. 31, 2020	Dec. 31, 2022
Tax Credit Carryforward [Line Items]
Qualified wages paid to employees	70%	50%
Maximum credit per employee	$ 7,000	$ 5,000
Maximum of wages per employees	$ 10,000
other income			$ 800

XOMA Transaction - Additional i

XOMA Transaction - Additional information (Detail) - USD ($) $ in Millions		12 Months Ended
	Mar. 22, 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
DOT-1 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 ($) $ in Thousands			1 Months Ended	12 Months Ended
	Nov. 04, 2021	Apr. 24, 2020	Jun. 30, 2021	Dec. 31, 2022	Dec. 31, 2021
Debt [Line Items]
Line of credit facility remaining	$ 45,000
Line Of credit facility borrowing capacity description				The second tranche of $20.0 million was drawn by the Company on December 29, 2022. The third tranche of $25.0 million remains available at the Company's request subject to the Lenders' discretion.
Debt Instrument, Interest Rate				11.90%
Tranche One [Member]
Debt [Line Items]
Line of credit facility remaining	20,000
Tranche Two [Member]
Debt [Line Items]
Line of credit facility remaining	25,000
Payment Protection Program Loan [Member]
Debt [Line Items]
Debt Instrument, Maturity Date		Apr. 23, 2022
Debt Instrument, Interest Rate		1%
Debt Instrument, Increase (Decrease), Net			$ 300
Debt and Lease Obligation					$ 0
Silicon Valley Bank [Member]
Debt [Line Items]
Repayments of Long-term Lines of Credit	5,000
Silicon Valley Bank [Member] | Contract Termination [Member]
Debt [Line Items]
Termination of Loan and Security agreement	15,000
Silicon Valley Bank [Member] | Maximum [Member]
Debt [Line Items]
Prepayment Fee Percentage				2%
Silicon Valley Bank [Member] | Minimum [Member]
Debt [Line Items]
Prepayment Fee Percentage				1%
First Republic Bank [Member] | Payment Protection Program Loan [Member]
Debt [Line Items]
Proceeds from Long-term Lines of Credit		$ 300
Silicon Valley Bank ("SVB") and Oxford Finance LLC ("Oxford") [Member]
Debt [Line Items]
Line of credit maximum borrowing amount	50,000
Line of credit facility remaining	45,000
Silicon Valley Bank ("SVB") and Oxford Finance LLC ("Oxford") [Member] | Tranche Two [Member]
Debt [Line Items]
Line of credit facility remaining	$ 20,000
Term Loan Agreement [Member] | Silicon Valley Bank [Member]
Debt [Line Items]
Debt Instrument, Maturity Date				Nov. 01, 2026
Debt Instrument, Interest Rate				4.90%
Debt Instrument Final Payment Interest Fee Percentage				5%
Term Loan Agreement [Member] | Silicon Valley Bank [Member] | Prime Rate [Member]
Debt [Line Items]
Debt Instrument, Interest Rate During Period				8.15%

Debt - Summary of Future Minimu

Debt - Summary of Future Minimum Payments Under Loan Facility (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
2023	$ 0
2024	8,571
2025	8,571
2026	7,858
Thereafter	0
Total Future minimum payments	25,000
Unamortized discount	(123)
Total, net	$ 24,877	$ 4,819

Merger - Additional Information

Merger - Additional Information (Detail) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) $ / shares shares
Business Acquisition [Line Items]
Estimated Fair value of total consideration | $	$ 103.4
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
Sunesis Pharmaceuticals Inc [Member]
Business Acquisition [Line Items]
Share price | $ / shares	$ 18.62

Merger - Summary of Allocation

Merger - Summary of Allocation of the Purchase Price To Assets and Liabilities Acquired (Detail) $ in Thousands	Dec. 31, 2022 USD ($)
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 ($)				1 Months Ended		12 Months Ended
	May 28, 2021	Feb. 24, 2021	Jan. 01, 2020	Jun. 30, 2022	Jan. 31, 2017	Dec. 31, 2022	Dec. 31, 2021	Jun. 30, 2021	Dec. 31, 2020	Jul. 30, 2020
Stockholders Equity [Line Items]
Common stock, shares outstanding						38,345,140	37,424,863
Price per common share						$ 1.46	$ 3.65
Common Stock, Shares, Issued						38,345,140	37,424,863
Proceeds from Issuance of Common Stock						$ 2,331,000	$ 62,320,000
Convertible Preferred Stock, Shares Issued upon Conversion						18,811,552
Preferred stock, shares authorized						10,000,000
Preferred stock, shares outstanding						10,248	10,248
Weighted average grant date fair value per share						$ 2.80	$ 6.25
Share of common stock value							$ 25,000
Common Stock, Shares Authorized						400,000,000	400,000,000
Weighted average exercise price						$ 5.57	$ 7.33
Stock reserved for future grant						9,717,600	6,429,819
Stock-based compensation						$ 13,548,000	$ 5,542,000
Stock option plan weighted average vesting period						8 years 9 months 18 days	8 years 10 months 24 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]
Stock Options Granted						10 years
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						67,540
Purchase price of a share as a percentage of fair market value						100%
Percentage Of Nonqualified Options Exercisable Price Of Fair Market Value Of Common Stock						100%
Weighted average exercise price						$ 30.22
Percentage of outstanding common stock							5%
2021 Inducement Plan [Member]
Stockholders Equity [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award Number of Shares Available for Issuance						235,000
Stock reserved for future grant								1,000,000
Director [Member] | 2021 Inducement Plan [Member]
Stockholders Equity [Line Items]
Increase In Authorized Capital						1,375,000
Common Stock, Shares Authorized						2,375,000
Employee Stock Option Member
Stockholders Equity [Line Items]
Stock-based compensation						$ 11,200,000	$ 4,800,000
Stock option plan weighted average vesting period						2 years 9 months 18 days
Unrecognised compensation expense related to unvested units						$ 16,200,000
Employee Stock Option Member | Chief Executive Officer [Member]
Stockholders Equity [Line Items]
NON RECURRING NON CASH EXPENSE						$ 4,000,000
Incentive Stock Options [Member] | Twenty Thousand and Sixteen Equity Incentive Plan [Member]
Stockholders Equity [Line Items]
Percentage of exercise price fair value					100%
Nonqualified Options [Member] | Twenty Thousand and Sixteen Equity Incentive Plan [Member]
Stockholders Equity [Line Items]
Percentage of exercise price fair value					85%
Restricted Stock Units [Member]
Stockholders Equity [Line Items]
Stock reserved for future grant						483,282	745,668
Stock-based compensation						$ 2,200,000	$ 700,000
Unrecognised compensation expense related to unvested units						$ 600,000
Restricted Stock units plan weighted average vesting period						2 years 4 months 24 days
Restricted Stock Units [Member] | Chief Executive Officer [Member]
Stockholders Equity [Line Items]
NON RECURRING NON CASH EXPENSE						$ 1,600,000
Minimum [Member] | Twenty Thousand and Sixteen Equity Incentive Plan [Member]
Stockholders Equity [Line Items]
Options,vesting period						0 years
Maximum [Member]
Stockholders Equity [Line Items]
Stock Options Granted						4 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]
Percentage of outstanding common stock						9.98%
Shares issuable upon conversion of preferred stock [Member]
Stockholders Equity [Line Items]
Stock reserved for future grant						292,799	292,799
Series E Convertible Preferred Stock [Member]
Stockholders Equity [Line Items]
Price per common share						$ 500
Preferred stock, shares outstanding						1,915
Convertible share price per share						$ 17.50
Series F Convertible Preferred Stock [Member]
Stockholders Equity [Line Items]
Price per common share						$ 600
Preferred stock, shares outstanding						8,333
Convertible share price per share						$ 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
Warrant [Member] | Common Warrants [Member]
Stockholders Equity [Line Items]
Class of warrant or right issued in period of warrants or rights						250,323
Common Stock [Member]
Stockholders Equity [Line Items]
Common Stock, Shares, Issued						564,125
Proceeds from Issuance of Common Stock						$ 2,300,000
Share Issued						38,345	37,425		906
Stock issued during period							5,173
Weighted average exercise price						$ 4.26
Stock Issued During Period, Shares, New Issues							12,012
Common Stock [Member] | Common Warrants [Member]
Stockholders Equity [Line Items]
Class of warrant or right, exercise price of warrants or rights						$ 0.09
Class of warrant or right issued remain unexercised						86,209
Warrant expiration period						7 years
Employee Stock Purchase Plan [Member]
Stockholders Equity [Line Items]
Share Issued						50,329
Shares Available for Future Grant						449,671
Purchase price of a share as a percentage of fair market value				85%			85%
Duration of offering period				6 months			12 months
Duration of each purchase period							6 months
Share of common stock value				$ 25,000,000
Stock reserved for future grant						449,671	60,948
Stock-based compensation						$ 100,000
Other Expenses							$ 0
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
Sales Agreement [Member] | Maximum [Member]
Stockholders Equity [Line Items]
Potential sales of common stock	$ 50,000,000

Stockholders' Equity - Shares o

Stockholders' Equity - Shares of Common Stock Reserved for Future Issuance (Detail) - shares	Dec. 31, 2022	Dec. 31, 2021
Class of Stock [Line Items]
Total common stock reserved for future issuance	9,717,600	6,429,819
Authorized for future option grants [Member]
Class of Stock [Line Items]
Total common stock reserved for future issuance	1,114,248	1,169,523
Common stock warrants [Member]
Class of Stock [Line Items]
Total common stock reserved for future issuance	109,309	109,309
Common stock authorized for the ESPP [Member]
Class of Stock [Line Items]
Total common stock reserved for future issuance	449,671	60,948
Stock options issued and outstanding for all plans [Member]
Class of Stock [Line Items]
Total common stock reserved for future issuance	7,268,291	4,051,572
RSUs outstanding [Member]
Class of Stock [Line Items]
Total common stock reserved for future issuance	483,282	745,668
Convertible preferred stock [Member]
Class of Stock [Line Items]
Total common stock reserved for future issuance	292,799	292,799

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Shared Based Compensation Cost Included in Consolidated Statement of Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share Based Compensation Cost Included in Condensed Statement Of Operations [Line Items]
Total stock-based compensation expense	$ 13,548	$ 5,542
Research and development [Member]
Share Based Compensation Cost Included in Condensed Statement Of Operations [Line Items]
Total stock-based compensation expense	2,782	2,122
General and administrative [Member]
Share Based Compensation Cost Included in Condensed Statement Of Operations [Line Items]
Total stock-based compensation expense	$ 10,766	$ 3,420

Stockholders' Equity - Summar_2

Stockholders' Equity - Summary of Fair Value of Stock Options is Estimated Using the Black-Scholes Model (Detail)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected dividend yield	0%	0%	0%
Minimum [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Risk free interest rate	1.82%	0.66%	3.63%
Expected option term	5 years 6 months	5 years 9 months 18 days	3 years 7 months 6 days
Expected volatility of common stock	82.70%	84.15%	85.20%
Maximum [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Risk free interest rate	3.97%	1.33%	3.82%
Expected option term	6 years 3 months 18 days	6 years 3 months 18 days	6 years
Expected volatility of common stock	86.20%	90.20%	91.40%

Stockholders' Equity - Summar_3

Stockholders' Equity - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Outstanding, Beginning Balance, Number of Shares	3,964,000
Options granted , Numbers of Shares	3,882,000
Options exercised , Numbers of Shares	(105,000)
Options Cancelled , Number of Shares	(540,000)
Outstanding, Ending Balance, Number of Shares	7,201,000	3,964,000
Vested and exercisable	2,247,000
Outstanding, Beginning Balance, Weighted Average Exercise Price Per Share	$ 7.33
Options granted, Weighted Average Exercise Price Per Share	3.79
Options exercised, Weighted Average Exercise Price Per Share	1.24
Options Cancelled , Weighted average exercise price	6.54
Outstanding, Ending Balance, Weighted Average Exercise Price Per Share	5.57	$ 7.33
Weighted Average Exercise Price, Vested and excercise	$ 6.80
Outstanding, Weighted Average Remaining Contractual Term (Years)	8 years 9 months 18 days	8 years 10 months 24 days
Vested and exercisable, Weighted Average Remaining Contractual Term (Years)	7 years 10 months 24 days
Outstanding, Intrinsic Value	$ 208	$ 1,973
Outstanding ending balance, Aggregate Intrinsic Value	208	$ 1,973
Vested and exercisable, Aggregate Intrinsic Value	$ 168
2011 Plan [Member]
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Outstanding, Ending Balance, Number of Shares	67,000
Outstanding and expected to vest as of December 31, 2022	7,201
Outstanding, Ending Balance, Weighted Average Exercise Price Per Share	$ 30.22
Outstanding and expected to vest as of December 31, 2022	$ 5.57
Outstanding, Weighted Average Remaining Contractual Term (Years)	3 years
Outstanding and expected to vest as of December 31, 2022	8 years 9 months 18 days
Outstanding, Intrinsic Value	$ 208
Outstanding ending balance, Aggregate Intrinsic Value	$ 208

Stockholders' Equity - Summar_4

Stockholders' Equity - Summary of Restricted Stock Units Activity (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share-Based Payment Arrangement [Abstract]
RSUs, Beginning balance	745,000
Granted	0
Vested	(198,000)
Cancelled	(64,000)
RSUs, Ending balance	483,000	745,000
Weighted Average Grant Date Fair Value per Share, Beginning balance	$ 4.22
Weighted Average Grant Date Fair Value per Share, Granted	0
Weighted Average Grant Date Fair Value per Share, Vested	3.94
Weighted Average Grant Date Fair Value per Share, Cancelled	8.01
Weighted Average Grant Date Fair Value per Share, Ending balance	$ 3.83	$ 4.22
Weighted Average Remaining Contractual Term (Years)	1 year 3 months 18 days	3 years 4 months 24 days

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Operating Loss Carryforwards [Line Items]
Income tax provision	$ 0	$ 0
Statutory income tax rate	21%	21%
Net valuation allowance, increased (decreased)	$ 11,300,000	$ 24,600,000
Orphan drug credit carryforwards	10,100,000
Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carry-forwards	165,500,000
Research and development tax credit carry-forwards	$ 1,500,000
Net operating loss carry-forwards expiration	2027
Operating loss carryforwards, not subject to expiration	$ 125,200,000
Research credit carryforwards expiration start year	2027
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carry-forwards	$ 106,600,000
Research and development tax credit carry-forwards	$ 2,300,000
Net operating loss carry-forwards expiration	2030

Income Taxes - Schedule of Defe

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred Tax Assets, Net [Abstract]
Federal and state net operating loss carryforwards	$ 41,179	$ 37,319
Federal and California research and development credit carryforwards	9,058	6,674
Share-based compensation expense	1,899	701
Capitalized 59(e) Expenses and Amortization	3,829	4,804
Section 174 Capitalized R&D Expenditures	4,768	0
Other, net	52	107
Total deferred tax assets	60,785	49,605
ROU asset	(56)	(134)
Total deferred tax liabilities	(56)	(134)
Net deferred tax assets before valuation allowance	60,729	49,471
Valuation allowance	(60,729)	(49,471)
Net deferred tax liability	$ 0	$ 0

Income Taxes - Schedule of Effe

Income Taxes - Schedule of Effective Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Federal statutory rate	21%	21%
State tax benefit, net of federal benefit	0%	7%
Valuation allowance	(23.00%)	(9.00%)
General business credits	5%	3%
Acquired IPR&D	0%	(21.00%)
Other	(3.00%)	(1.00%)
Effective income tax rate	0%	0%

Income Taxes - Schedule of Unre

Income Taxes - Schedule of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Gross unrecognized tax benefits at the beginning of the year	$ 4,962	$ 3,971
Additions based on tax positions related to the current year	884	991
Additions for tax positions of prior years	(65)	0
Gross unrecognized tax benefits at the end of the year	$ 5,781	$ 4,962

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($)		1 Months Ended	12 Months Ended
	Aug. 31, 2020	Jun. 30, 2020	Dec. 31, 2022	Dec. 31, 2021
Loss Contingencies [Line Items]
Lease liability			$ 278,000
Operating lease right-of-use asset			266,000	$ 640,000
Operating Lease Expense			400,000	600,000
Cash paid for amounts included in the measurement of operating lease liabilities			$ 400	$ 500
Description of lessee leasing arrangements new or amended			There were no new or amended lease arrangements executed in 2022 or 2021.
Lessee, Operating Lease, Description		August 2023
Lessee, Operating Lease, Option to Extend		option for an additional year
Lessee, Operating Lease, Option to Terminate	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
Original Operating Lease [Member]
Loss Contingencies [Line Items]
Operating lease right-of-use asset			$ 300,000
Noncancelable operating lease agreement [Member] | Amended Operating Lease [Member]
Loss Contingencies [Line Items]
Operating lease right-of-use asset		$ 700,000
Percentage of increase in monthly base rent		4%
Additional noncancelable operating lease agreement [Member] | New Operating Lease [Member]
Loss Contingencies [Line Items]
Operating lease right-of-use asset	$ 400,000
Lessee, Operating Lease, Description	August 2020 through August 2023
Lessee, Operating Lease, Option to Extend	option for an additional year
Maximum [Member] | Noncancelable operating lease agreement [Member] | Amended Operating Lease [Member]
Loss Contingencies [Line Items]
Operating leases rent expense		$ 21,444,000
Maximum [Member] | Additional noncancelable operating lease agreement [Member] | New Operating Lease [Member]
Loss Contingencies [Line Items]
Cash paid for amounts included in the measurement of operating lease liabilities	$ 14,033,000
Percentage of increase in monthly base rent	9%
Minimum [Member] | Noncancelable operating lease agreement [Member] | Amended Operating Lease [Member]
Loss Contingencies [Line Items]
Operating leases rent expense		$ 20,019,000
Minimum [Member] | Additional noncancelable operating lease agreement [Member] | New Operating Lease [Member]
Loss Contingencies [Line Items]
Cash paid for amounts included in the measurement of operating lease liabilities	$ 12,462,000
Percentage of increase in monthly base rent	4%

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Future Minimum Payments for Operating Leases (Details) $ in Thousands	Dec. 31, 2022 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2022	$ 284
Thereafter	0
Total lease payments	284
Less: imputed interest	(6)
Total operating lease liabilities	$ 278

Commitments and Contingencies_3

Commitments and Contingencies - Schedule Of Cash Flow Supplemental Disclosures (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Supplemental Cash Flow Information [Abstract]
Cash paid for amounts included in the measurement of operating lease liabilities	$ 400	$ 500
weighted average discount rate	8%
weighted average remaining lease term	8 months 12 days