Viracta Therapeutics (VIRX) 10-K 7 Mar 24 2023 FY Annual report Financial data

Cover Page

Cover Page - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Mar. 04, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2023
Document Fiscal Year Focus	2023
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		39,272,434
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
Entity File Number	000-51531
Entity Tax Identification Number	94-3295878
Entity Address, Address Line One	2533 S. Coast Hwy. 101, Suite 210
Entity Address, City or Town	Cardiff
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92007
Entity Public Float			$ 50.2
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 2024 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, 2023
Document Financial Statement Error Correction [Flag]	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current Assets:
Cash and cash equivalents	$ 12,317	$ 36,773
Short-term investments	41,374	54,270
Prepaid expenses and other current assets	1,273	2,704
Total current assets	54,964	93,747
Property and equipment, net	190	148
Operating lease right-of-use asset	274	266
Other assets	1,264	1,830
Total assets	56,692	95,991
Current Liabilities:
Accounts payable	2,441	2,540
Accrued expenses	10,376	7,193
Operating lease liabilities	282	278
Current portion of long-term debt, net	25,274	0
Total current liabilities	38,373	10,011
Long-term debt, net	0	24,877
Total liabilities	38,373	34,888
Stockholders' equity:
Convertible preferred stock, $0.0001 par value; 10,000,000 shares authorized as of December 31, 2023; 10,248 shares issued and outstanding as of December 31, 2023 and December 31, 2022	5,452	5,452
Common stock, $0.0001 par value; 400,000,000 shares authorized; 39,093,509 and 38,345,140 shares issued and outstanding at December 31, 2023 and December 31, 2022, respectively	4	4
Additional paid-in capital	278,786	270,699
Accumulated other comprehensive income (loss)	9	(178)
Accumulated deficit	(265,932)	(214,874)
Total stockholders' equity	18,319	61,103
Total liabilities and stockholders' equity	$ 56,692	$ 95,991

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	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	39,093,509	38,345,140
Common stock, shares outstanding	39,093,509	38,345,140

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Operating expenses:
Research and development	$ 33,369	$ 26,262
General and administrative	17,324	24,327
Total operating expenses	50,693	50,589
Loss from operations	(50,693)	(50,589)
Other income (expense):
Interest income	3,345	1,171
Interest expense	(3,704)	(577)
Other income	(6)	798
Total other income (expense)	(365)	1,392
Net loss	(51,058)	(49,197)
Unrealized gain (loss) on short-term investments	187	(178)
Comprehensive loss	$ (50,871)	$ (49,375)
Net loss per share of common stock, basic	$ (1.32)	$ (1.3)
Net loss per share of common stock, diluted	$ (1.32)	$ (1.3)
Weighted-average shares used to compute basic net loss per share	38,624,462	37,790,981
Weighted-average shares used to compute diluted net loss per share	38,624,462	37,790,981

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Preferred Stock Shares issuable upon conversion of preferred stock [Member]	Accumulated Other Comprehensive Gain (Loss)
Beginning Balance at Dec. 31, 2021	$ 94,371	$ 4	$ 254,592	$ (165,677)	$ 5,452
Beginning 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		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 gain (loss) on short-term investments	(178)					$ (178)
Net Income (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
Exercise of warrants and stock options to purchase common stock	$ 139		139
Issuance of common stock upon exercise of stock options and from employee stock plan	17	192
Issuance of common stock through "at the market" offering net shares		372
Issuance of common stock through "at the market" offering, net, Value	$ 299		299
Issuance of common stock upon vesting of restricted stock units		185
Share-based compensation	7,649		7,649
Unrealized gain (loss) on short-term investments	187					187
Net Income (Loss)	(51,058)			(51,058)
Ending Balance at Dec. 31, 2023	$ 18,319	$ 4	$ 278,786	$ (265,932)	$ 5,452	$ 9
Ending Balance, shares at Dec. 31, 2023		39,094			10

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Operating activities
Net Income (Loss)	$ (51,058)	$ (49,197)
Adjustments to reconcile net loss to net cash used in by operating activities:
Share-based compensation expense	7,649	13,548
Depreciation and amortization	492	210
Amortization of premiums and accretion of discounts on short-term investments, net	(2,054)	(626)
Change in operating assets and liabilities:
Prepaid expenses and other current assets	1,431	(985)
Other assets	566	567
Accounts payable	(98)	(361)
Accrued expenses	3,184	1,394
Lease liabilities, net	(4)	(7)
Net cash used in operating activities	(39,892)	(35,457)
Investing activities
Purchases of property and equipment	(138)	(45)
Purchases of short-term investments	(67,136)	(70,620)
Proceeds from maturity of short-term investments	82,272	16,799
Net cash provided by (used in) investing activities	14,998	(53,866)
Financing activities
Proceeds from debt, net of issuance costs	0	19,986
Issuance of common stock, net of issuance costs	299	2,331
Issuance of common stock upon option exercises and from employee stock plan	139	225
Net cash provided by financing activities	438	22,542
Net decrease in cash and cash equivalents	(24,456)	(66,781)
Cash and cash equivalents at beginning of period	36,773	103,554
Cash and cash equivalents at end of period	12,317	36,773
Supplemental disclosure of cash flow information
Interest paid	3,070	454
Interest received	3,344	1,171
Operating lease right-of-use assets obtained in exchange for operating lease liabilities	$ 381	$ 0

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Pay vs Performance Disclosure
Net Income (Loss)	$ (51,058)	$ (49,197)

Insider Trading Arrangements

Insider Trading Arrangements	12 Months Ended
	Dec. 31, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Organization and Basis of Prese

Organization and Basis of Presentation	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	1. Organization and Basis of Presentation Viracta Therape utics, 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 clinical-stage, precision oncology company focused on the treatment and prevention of virus-associated cancers that impact patients worldwide. 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. 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, the transactions contemplated by the Merger Agreement were completed, and Merger Sub merged into Private Viracta, with Private Viracta 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. Liquidity and Capital Resources As of December 31, 2023, 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, 2023, had an accumulated deficit of $ 265.9 million. The Company expects to continue to incur net losses and operating cash outflows 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. Based on the Company's current financial position and business plan, the Company will need to raise additional capital through the issuance of its common stock, through other equity or debt financings or through collaborations or partnerships with other companies, to fund its continued operations. The Company may be unable to raise additional funds or to enter into such agreements or arrangements on favorable terms, or at all. If the Company is unable to raise capital or enter into such agreements as and when needed, it may have to significantly delay, scale back or discontinue the development or commercialization of one or more of its product candidates. As of December 31, 2023, the Company had cash, cash equivalents and short-term investments of approximately $ 53.7 million and working capital of $ 16.6 million. On November 4, 2021, the Company entered into a loan and security agreement with Silicon Valley Bank, now a division of First-Citizens Bank and Trust Company (“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. The availability of the additional tranche of $25.0 million, previously available under certain conditions, expired on December 31, 2023. Based on the Company’s current financial position and business plan, management believes that its existing cash, cash equivalents and short-term investments may not be sufficient to fund the Company’s planned operations for at least twelve months from the issuance date of these consolidated financial statements. The Company’s current liquidity position, recurring net losses from operations and negative cash flows from operating activities raise substantial doubt about its ability to continue as a going concern. Because management’s equity and/or debt financing plans, along with collaborative or other funding arrangements have not yet been executed and are not fully within the Company’s control, such plans cannot be considered probable of being achieved. As a result, the Company has concluded that management’s plans do not alleviate substantial doubt about the Company’s ability to continue as a going concern. Due to these circumstances and based on management's assessment that the material adverse change clause under the SVB-Oxford Loan Facility (see Note 5) is not within the Company's control, all amounts due under the SVB-Oxford Loan Facility have been classified as a current liability as of December 31, 2023. The accompanying consolidated financial statements have been prepared on a basis which assumes the Company will be able to continue as a going concern, and do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts and classifications of liabilities that may result from any uncertainty related to its ability to continue as a going concern. The COVID-19 pandemic caused significant business disruption around the globe and its long-term impact remains uncertain. While the World Health Organization has determined that COVID-19 no longer represents a global health emergency and the Company has largely resumed normal operations, any resurgence or worsening of the COVID-19 pandemic may cause the Company to reinstitute certain mitigating measures. The Company does not yet know the full extent of potential delays or impacts on its business, its clinical trials, healthcare systems or the global economy as a whole. These effects could have a material impact on the Company’s 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, 2023
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. 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. 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, 2023 , the Company had one contract lab that provided 23.9 % of total third-party services. For the year ended December 31, 2022 , the Company had two contract labs that provided 23.2 % of total third-party services. 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. 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. 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. 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 . Capitalized Software Implementation Costs The Company capitalizes certain implementation costs incurred related to cloud computing arrangements that are service contracts. Such costs are amortized on a straight-line basis over the term of the associated hosting arrangement plus any reasonably certain renewal period. Any capitalized amounts related to such arrangements are recorded within prepaid expenses and other current assets and within property and equipment, net on the Company's balance sheets. 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 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, 2023 and December 31, 2022 . Fair Value Measurements 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 as of December 31, 2023 and December 31, 2022, in thousands: December 31, 2023 Maturities Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash equivalents: Money market funds 1 or less $ 9,535 $ — $ — $ 9,535 Commercial paper 1 or less 499 — — 499 Total cash equivalents 10,034 — — 10,034 Short-term investments: U.S. Treasury securities 2 or less 11,371 8 — 11,379 Commercial paper 1 or less 14,931 10 — 14,941 Corporate debt securities 2 or less 3,796 4 — 3,800 U.S. Agency bonds 1 or less 11,267 — ( 13 ) 11,254 Total short-term investments 41,365 22 ( 13 ) 41,374 Total $ 51,399 $ 22 $ ( 13 ) $ 51,408 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, 2023, 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, 2023, no allowance for credit losses was recorded and the Company did not recognize any impairment losses related to investments. None of the short-term investments were in a continuous unrealized loss position for a period greater than 12 months as of December 31, 2023 and December 31, 2022. Accrued interest receivable on available-for-sale securities wa s $ 0.1 million at December 31, 2023 and December 31, 2022 . We have no t written off any accrued interest receivables for the years ended December 31, 2023 and 2022. The fair value of financial instruments is classified into one of the following categories based upon the lowest level of input that is significant to the fair value measurement: 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. Belo w is a summary of assets, including cash equivalents and short-term investments, measured at fair value as of December 31, 2023 and December 31, 2022, in thousands. Fair Value Measurements Using December 31, 2023 Level 1 Level 2 Cash equivalents: Money market funds $ 9,535 $ 9,535 $ — Commercial paper 499 — 499 Total cash equivalents 10,034 9,535 499 Short-term investments: U.S. Treasury securities 11,379 11,379 — Commercial paper 14,941 — 14,941 Corporate debt securities 3,800 — 3,800 U.S. Agency bonds 11,254 — 11,254 Total short-term investments 41,374 11,379 29,995 Total $ 51,408 $ 20,914 $ 30,494 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 — 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 Company had no liabilities measured at fair value on a recurring basis as of December 31, 2023 and December 31, 2022 . 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, 2023 2022 Shares issuable upon conversion of preferred stock 292,799 292,799 Common stock options and RSUs outstanding 9,596,644 7,751,573 ESPP shares pending issuance 21,212 11,718 Warrants to purchase common stock 23,100 23,100 Total excluded securities 9,933,755 8,079,190 Recently Issued Accounting Pronouncements In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures , which is intended to enhance the transparency and decision usefulness of income tax disclosures, primarily related to the rate reconciliation and income taxes paid. This ASU is effective for annual periods beginning after December 15, 2024, and may be adopted on a prospective or retrospective basis. Early adoption is permitted. The Company is currently evaluating the impact this standard will have on its consolidated financial statements.

Collaboration and License Agree

Collaboration and License Agreements	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaboration and License Agreements	3. Collaboration and License Agreements 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. XOMA Transaction In December 2019, the Company entered into a license agreement with Day One Biopharmaceuticals, Inc. ("Day One," formerly known as DOT Therapeutics-1, Inc.) to grant Day One a worldwide, exclusive license of DAY101. The Day One 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, defined below. On March 22, 2021, the Company entered into a Royalty Purchase Agreement with XOMA (US) LLC (“XOMA”), in which XOMA purchased the potential future milestones and royalties associated with existing licenses relating to two clinical-stage product candidates, DAY101 and vosaroxin, which were obtained in the Merger (the “XOMA Transaction”). The Company received, and recorded as a gain in the statement of operations and comprehensive loss for the period, an upfront payment of $ 13.5 million, and retained a pre-commercialization, event-based milestone. For the years ended December 31, 2023 and 2022, the Company recognized no income pursuant to this milestone .

Financial Statement Details

Financial Statement Details	12 Months Ended
	Dec. 31, 2023
Financial Statement Details [Abstract]
Financial Statement Details	4. Financial Statement Details Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consist of the following (in thousands): December 31, December 31, 2023 2022 Prepaid expenses $ 276 $ 780 ERC receivable 168 798 Prepaid insurance 581 567 Current deposits 135 442 Accrued interest receivable 113 112 Other — 5 Total prepaid expenses and other current assets $ 1,273 $ 2,704 For the year ended December 31, 2022, the Company recorded the $ 0.8 million receivable for the Employee Retention Credit (the "ERC"), after determining that the amount was both estimable and reasonably assured of collection. As of December 31, 2023, $ 0.6 million of the ERC receivable had been received. Accrued Expenses Accrued expenses consist of the following (in thousands): December 31, December 31, 2023 2022 Accrued payroll and benefits $ 3,374 $ 2,961 Accrued clinical trial and contract expenses 6,456 3,562 Accrued professional services and expenses 258 385 Other accrued expenses 288 285 Total accrued expenses $ 10,376 $ 7,193

Debt

Debt	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Debt	5. 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 SVB and Oxford for up to $ 50.0 million. The existing $ 5.0 million debt balance from the Company’s previous credit facility with SVB was replaced under this SVB-Oxford Loan Facility. 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 availability of the additional tranche of $ 25.0 million, previously available under certain conditions, expired on December 31, 2023. 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. As the Milestone was not met as of December 31, 2023, the period of interest only will be followed by 35 equal monthly payments of principal plus accrued interest commencing on January 1, 2024, subject to a Second Amendment to the SVB-Oxford Loan Facility entered on March 1, 2024, as further described in Note 9. T he 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, 2023, the per annum interest rate was 13.40 % . 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. The Company is subject to customary affirmative and restrictive covenants under the SVB-Oxford Loan Facility which also contains customary indemnification obligations and customary events of default, including a material adverse change clause. 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, 2023, the Company is in compliance with all nonfinancial and financial covenants under the SVB-Oxford Loan Facility and there has 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, 2023. The following table summarizes future principal payments, including the final payment, under the terms of the SVB-Oxford Loan Facility as of December 31, 2023 (in thousands): Years Ending December 31, 2024 $ 8,571 2025 8,571 2026 7,858 Total future principal payments 25,000 Final payment 397 Unamortized discount ( 123 ) Total, net $ 25,274

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2023
Stockholders' Equity Note [Abstract]
Stockholders' Equity	6. Stockholders’ Equity Common Stock The total number of shares of common stock of Viracta outstanding as of December 31, 2023 and December 31, 2022 was 39,093,509 and 38,345,140 , respectively. 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. The Company is currently eligible to sell securities under Form S-3 only if and to the extent the aggregate market value of securities sold pursuant to General Instruction I.B.6 of Form S-3 during the twelve-month period immediately prior to, and including, the date of any such sale, does not exceed one-third of the aggregate market value of the Company's common stock held by non-affiliates (as determined by General Instruction I.B.6 of Form S-3), and the Company will remain subject to such limitation for so long as the aggregate market value of its common stock held by non-affiliates is less than $ 75 million (as determined by General Instruction I.B.6 of Form S-3). As such, the Company will be limited in its ability to access additional funding from the sale of securities under Form S-3. 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). For the year ended December 31, 2023, the Company sold 371,675 shares of its common stock pursuant to the Sales Agreement at a weighted average price per share of $ 0.83 for $ 0.3 million, net of commissions. For the year ended December 31, 2022 , the Company sold 564,125 shares of its common stock pursuant to the Sale Agreement at a weighted average price per share of $ 4.26 for $ 2.3 million, net of commissions. As of December 31, 2023, the Company had approximately $ 47.3 million available under the Sale Agreement. Convertible Preferred Stock In connection with the Merger, all of the outstanding shares of Private Viracta’s convertible preferred stock were converted into 18,811,552 shares of the Company’s common stock. 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, 2023 and 2022, 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, 2023, 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, 2023 and 2022, 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 original 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, 2023 2022 Conversion of preferred stock 292,799 292,799 Common stock warrants 109,309 109,309 Stock options issued and outstanding for all plans 9,349,791 7,268,291 RSUs outstanding 246,853 483,282 Authorized for future option grants 723,977 1,114,248 Common stock authorized for the ESPP 658,955 449,671 Total 11,381,684 9,717,600 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, 2023 , no vested options remain outstanding under the Sunesis 2011 Plan. The share-based compensation recorded in the accompanying consolidated statements of operations for the years ended December 31, 2023 and 2022 is presented below (in thousands): Year Ended December 31, 2023 2022 Research and development $ 2,574 $ 2,782 General and administrative 5,075 10,766 Total $ 7,649 $ 13,548 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, 2023, there were zero shares available for issuance under the 2021 Inducement Plan. Stock Options The Company recorded share-based compensation related to stock options of $ 7.3 mi llion and $ 11.2 million for the years ended December 31, 2023 and 2022 , 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. 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, 2023 2022 Risk free interest rate 3.37 % - 4.39 % 1.82 % - 3.97 % Expected option term 5.8 - 6.3 years 5.5 - 6.3 years Expected volatility of common stock 86.9 % - 92.1 % 82.7 % - 86.2 % Expected dividend yield 0.0 % 0.0 % The fair value of the former Chief Executive Officer option modifications in 2022 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, 2023, unrecognized compensation expense related to unvested options granted totaled $ 10.9 million. The expense is expected to be recognized over a weighted-average period of 2.2 years. A summary of the stock option activity under the plans during the period ended December 31, 2023 is presented below (in thousands except for per share and weighted average term): Number of Weighted Weighted Aggregate Intrinsic Value Outstanding at December 31, 2022 7,201 $ 5.57 8.8 $ 208 Granted 3,176 $ 1.55 Exercised ( 17 ) $ 0.90 $ 18 Cancelled ( 1,010 ) $ 4.32 Outstanding at December 31, 2023 9,350 $ 4.35 8.3 $ 1 Vested and exercisable at December 31, 2023 4,348 $ 5.32 7.7 $ — Outstanding and expected to vest as of December 31, 2023 9,350 $ 4.35 8.3 $ 1 Aggregate intrinsic values are based upon a common stock price of $ 0.57 and $ 1.46 at December 31, 2023 and 2022, 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, 2023 and 2022 was $ 1.17 and $ 2.80 , respectively. Restricted Stock Units The Company recorded share-based compensation related to RSUs of $ 0.2 million and $ 2.2 million for the years ended December 31, 2023 and 2022 , 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. 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, 2023 is presented below (in thousands except for per share and weighted average term): RSUs Weighted Weighted Outstanding at December 31, 2022 483 $ 3.83 1.3 Granted — — Vested ( 185 ) $ 4.06 Cancelled ( 51 ) $ 8.16 Outstanding at December 31, 2023 247 $ 3.58 0.8 As of December 31, 2023, unrecognized compensation expense related to unvested RSUs totaled $ 0.3 million. The expense is expected to be recognized over a weighted-average period of 1.4 years. Employee Stock Purchase Plan 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, 2023, there were 224,496 shares issued, and 658,955 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 years ended December 31, 2023 and 2022 .

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. 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”). In February 2023, the Company exercised the option for a one-year extension of the Amended Lease, extending the lease term from August 2023 to August 2024. The Amended Lease monthly base rent will increase approximately 4 % annually from $ 20,019 to $ 22,195 over the life of the lease, including utilities and other operating costs. Upon the execution of the one-year extension on the Amended Lease, the Company recorded an additional operating lease right-of-use (“ROU”) asset and corresponding lease liability for $ 0.2 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”). In February 2023, the Company exercised the option for a one-year extension of the New Lease, extending the lease term from August 2023 to August 2024. 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 includes annual increases that range between 4 % to 9 % from $ 12,462 to $ 14,524 over the life of the lease, including utilities and other operating costs. In connection with the execution of the one-year extension on the New Lease, the Company recorded an additional operating lease ROU asset and corresponding lease liability for $ 0.2 million. The following table summarizes future minimum payments under the Company's operating leases as of December 31, 2023 (in thousands): Year Ending December 31, 2024 $ 294 Total lease payments 294 Less: imputed interest ( 12 ) Total operating lease liabilities $ 282 Total lease expense was $ 0.4 million for the years ended December 31, 2023 and 2022. At December 31, 2023, the Company had remaining current lease liabilities of approximately $ 0.3 million and operating lease ROU assets of $ 0.3 million. Other supplemental cash flow information consisted of the following: Year Ended 2023 2022 Cash paid for amounts included in the measurement of operating lease liabilities $ 0.4 $ 0.4 Other supplemental information, as of December 31, 2023 and 2022, consisted of the following: Year Ended 2023 2022 Weighted-average discount rate 14.8 % 8.0 % Weighted-average remaining lease term (in years) 0.7 0.7 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, 2023
Income Tax Disclosure [Abstract]
Income Taxes	8. 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, 2023 and 2022. Significant components of the Company’s deferred tax assets and liabilities as of December 31, 2023 and 2022 are detailed below (in thousands). Year Ended December 31, 2023 2022 Deferred tax assets: Federal and state net operating loss carryforwards $ 45,942 $ 41,179 Federal and California research and development credit carryforwards 11,987 9,058 Share-based compensation expense 2,297 1,899 Capitalized 59(e) Expenses and Amortization 3,274 3,829 Section 174 Capitalized R&D Expenditures 9,717 4,768 Other, net 57 52 Total deferred tax assets 73,274 60,785 ROU asset ( 58 ) ( 56 ) Total deferred tax liabilities ( 58 ) ( 56 ) Net deferred tax asset 73,216 60,729 Valuation allowance ( 73,216 ) ( 60,729 ) 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, 2023 and 2022 due to the following: Year Ended December 31, 2023 2022 % % Federal statutory rate 21 21 State tax benefit, net of federal benefit — — Valuation allowance ( 25 ) ( 23 ) General business credits 6 5 Other ( 2 ) ( 3 ) Effective income tax rate — — At December 31, 2023, the Company had federal and state net operating loss carryforwards o f $ 188.2 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 $ 147.9 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 $ 2.7 million, re spectively. Additionally, the Company has Orphan Drug Credit carryforwards of $ 13.6 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 $ 12.5 million and $ 11.3 million for the years ended December 31, 2023 and December 31, 2022, 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, 2023 2022 Gross unrecognized tax benefits at the beginning of the year $ 5,781 $ 4,962 Additions based on tax positions related to the current year 998 884 Reductions for tax positions of prior years — ( 65 ) Gross unrecognized tax benefits at the end of the year $ 6,779 $ 5,781 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, 2023, 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, 2023
Subsequent Events [Abstract]
Subsequent Events	9. Subsequent Events On March 4, 2024, the Company entered into an Amendment No. 1 (the “Day One Amendment”) to the License Agreement for RAF, dated as of December 16, 2019, by and between the Company and Day One Biopharmaceuticals, Inc., successor in interest to DOT Therapeutcs-1, Inc., to monetize a pre-commercialization, event-based milestone for $5.0 million to be received in March 2024, thereby reducing the milestone percentage under the agreement. On March 4, 2024, in connection with the entry into the Day One Amendment, the Company entered into an Amendment No. 1 to the Royalty Purchase Agreement, dated as March 22, 2021, by and between the Company and XOMA (US) LLC (See Note 3), modifying the economic value-share under the Royalty Purchase Agreement, by which the Company has retained the right, under certain circumstances, to participate in a pre-commercialization, event-based milestone up to $5.0 million. On March 1, 2024, the Company entered into a Second Amendment (the “Second Amendment”) to the Loan and Security Agreement by and among the Company and Silicon Valley Bank, now a division of First-Citizens Bank and Trust Company, and Oxford Finance LLC, dated November 4, 2021 (See Note 5), as previously amended, providing for a modification of the loan amortization period and a pro rata reduction in the prospective debt amortization schedule, in exchange for a partial prepayment of the term loan. Pursuant to the terms of the Second Amendment, the Company has agreed to remit a prepayment of $5.0 million toward the outstanding principal, plus a pro rata portion of the final payment, by March 15, 2024. Under the terms of the Second Amendment, principal amortization will be deferred between March 2024 and June 2024, and during such time we will be required to make payments of interest-only. Principal amortization payments will recommence in July 2024, followed by 29 equal monthly payments of principal plus accrued interest through maturity. There were no changes to the maturity date of the term loan.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2023
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.
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. 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, 2023 , the Company had one contract lab that provided 23.9 % of total third-party services. For the year ended December 31, 2022 , the Company had two contract labs that provided 23.2 % of total third-party services.
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.
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.
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.
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
Capitalized Software Implementation Costs	Capitalized Software Implementation Costs The Company capitalizes certain implementation costs incurred related to cloud computing arrangements that are service contracts. Such costs are amortized on a straight-line basis over the term of the associated hosting arrangement plus any reasonably certain renewal period. Any capitalized amounts related to such arrangements are recorded within prepaid expenses and other current assets and within property and equipment, net on the Company's balance sheets.
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 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, 2023 and December 31, 2022 .
Fair Value Measurements	Fair Value Measurements 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 as of December 31, 2023 and December 31, 2022, in thousands: December 31, 2023 Maturities Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash equivalents: Money market funds 1 or less $ 9,535 $ — $ — $ 9,535 Commercial paper 1 or less 499 — — 499 Total cash equivalents 10,034 — — 10,034 Short-term investments: U.S. Treasury securities 2 or less 11,371 8 — 11,379 Commercial paper 1 or less 14,931 10 — 14,941 Corporate debt securities 2 or less 3,796 4 — 3,800 U.S. Agency bonds 1 or less 11,267 — ( 13 ) 11,254 Total short-term investments 41,365 22 ( 13 ) 41,374 Total $ 51,399 $ 22 $ ( 13 ) $ 51,408 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, 2023, 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, 2023, no allowance for credit losses was recorded and the Company did not recognize any impairment losses related to investments. None of the short-term investments were in a continuous unrealized loss position for a period greater than 12 months as of December 31, 2023 and December 31, 2022. Accrued interest receivable on available-for-sale securities wa s $ 0.1 million at December 31, 2023 and December 31, 2022 . We have no t written off any accrued interest receivables for the years ended December 31, 2023 and 2022. The fair value of financial instruments is classified into one of the following categories based upon the lowest level of input that is significant to the fair value measurement: 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. Belo w is a summary of assets, including cash equivalents and short-term investments, measured at fair value as of December 31, 2023 and December 31, 2022, in thousands. Fair Value Measurements Using December 31, 2023 Level 1 Level 2 Cash equivalents: Money market funds $ 9,535 $ 9,535 $ — Commercial paper 499 — 499 Total cash equivalents 10,034 9,535 499 Short-term investments: U.S. Treasury securities 11,379 11,379 — Commercial paper 14,941 — 14,941 Corporate debt securities 3,800 — 3,800 U.S. Agency bonds 11,254 — 11,254 Total short-term investments 41,374 11,379 29,995 Total $ 51,408 $ 20,914 $ 30,494 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 — 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 Company had no liabilities measured at fair value on a recurring basis as of December 31, 2023 and December 31, 2022 .
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, 2023 2022 Shares issuable upon conversion of preferred stock 292,799 292,799 Common stock options and RSUs outstanding 9,596,644 7,751,573 ESPP shares pending issuance 21,212 11,718 Warrants to purchase common stock 23,100 23,100 Total excluded securities 9,933,755 8,079,190
Recently Accounting Pronouncements	Recently Issued Accounting Pronouncements In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures , which is intended to enhance the transparency and decision usefulness of income tax disclosures, primarily related to the rate reconciliation and income taxes paid. This ASU is effective for annual periods beginning after December 15, 2024, and may be adopted on a prospective or retrospective basis. Early adoption is permitted. The Company is currently evaluating the impact this standard will have on its consolidated financial statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2023
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 as of December 31, 2023 and December 31, 2022, in thousands: December 31, 2023 Maturities Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash equivalents: Money market funds 1 or less $ 9,535 $ — $ — $ 9,535 Commercial paper 1 or less 499 — — 499 Total cash equivalents 10,034 — — 10,034 Short-term investments: U.S. Treasury securities 2 or less 11,371 8 — 11,379 Commercial paper 1 or less 14,931 10 — 14,941 Corporate debt securities 2 or less 3,796 4 — 3,800 U.S. Agency bonds 1 or less 11,267 — ( 13 ) 11,254 Total short-term investments 41,365 22 ( 13 ) 41,374 Total $ 51,399 $ 22 $ ( 13 ) $ 51,408 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, 2023 and December 31, 2022, in thousands. Fair Value Measurements Using December 31, 2023 Level 1 Level 2 Cash equivalents: Money market funds $ 9,535 $ 9,535 $ — Commercial paper 499 — 499 Total cash equivalents 10,034 9,535 499 Short-term investments: U.S. Treasury securities 11,379 11,379 — Commercial paper 14,941 — 14,941 Corporate debt securities 3,800 — 3,800 U.S. Agency bonds 11,254 — 11,254 Total short-term investments 41,374 11,379 29,995 Total $ 51,408 $ 20,914 $ 30,494 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 — 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 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, 2023 2022 Shares issuable upon conversion of preferred stock 292,799 292,799 Common stock options and RSUs outstanding 9,596,644 7,751,573 ESPP shares pending issuance 21,212 11,718 Warrants to purchase common stock 23,100 23,100 Total excluded securities 9,933,755 8,079,190

Financial Statement Details (Ta

Financial Statement Details (Tables)	12 Months Ended
	Dec. 31, 2023
Financial Statement Details [Abstract]
Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consist of the following (in thousands): December 31, December 31, 2023 2022 Prepaid expenses $ 276 $ 780 ERC receivable 168 798 Prepaid insurance 581 567 Current deposits 135 442 Accrued interest receivable 113 112 Other — 5 Total prepaid expenses and other current assets $ 1,273 $ 2,704
Schedule of Accrued Liabilities	Accrued expenses consist of the following (in thousands): December 31, December 31, 2023 2022 Accrued payroll and benefits $ 3,374 $ 2,961 Accrued clinical trial and contract expenses 6,456 3,562 Accrued professional services and expenses 258 385 Other accrued expenses 288 285 Total accrued expenses $ 10,376 $ 7,193

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Summary of Future Minimum Payments Under Loan Facility	The following table summarizes future principal payments, including the final payment, under the terms of the SVB-Oxford Loan Facility as of December 31, 2023 (in thousands): Years Ending December 31, 2024 $ 8,571 2025 8,571 2026 7,858 Total future principal payments 25,000 Final payment 397 Unamortized discount ( 123 ) Total, net $ 25,274

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2023
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, 2023 2022 Conversion of preferred stock 292,799 292,799 Common stock warrants 109,309 109,309 Stock options issued and outstanding for all plans 9,349,791 7,268,291 RSUs outstanding 246,853 483,282 Authorized for future option grants 723,977 1,114,248 Common stock authorized for the ESPP 658,955 449,671 Total 11,381,684 9,717,600
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, 2023 and 2022 is presented below (in thousands): Year Ended December 31, 2023 2022 Research and development $ 2,574 $ 2,782 General and administrative 5,075 10,766 Total $ 7,649 $ 13,548
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, 2023 2022 Risk free interest rate 3.37 % - 4.39 % 1.82 % - 3.97 % Expected option term 5.8 - 6.3 years 5.5 - 6.3 years Expected volatility of common stock 86.9 % - 92.1 % 82.7 % - 86.2 % Expected dividend yield 0.0 % 0.0 % The fair value of the former Chief Executive Officer option modifications in 2022 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 plans during the period ended December 31, 2023 is presented below (in thousands except for per share and weighted average term): Number of Weighted Weighted Aggregate Intrinsic Value Outstanding at December 31, 2022 7,201 $ 5.57 8.8 $ 208 Granted 3,176 $ 1.55 Exercised ( 17 ) $ 0.90 $ 18 Cancelled ( 1,010 ) $ 4.32 Outstanding at December 31, 2023 9,350 $ 4.35 8.3 $ 1 Vested and exercisable at December 31, 2023 4,348 $ 5.32 7.7 $ — Outstanding and expected to vest as of December 31, 2023 9,350 $ 4.35 8.3 $ 1
Summary of Restricted Stock Units Activity	A summary of the restricted stock unit activity under the plans during the period ended December 31, 2023 is presented below (in thousands except for per share and weighted average term): RSUs Weighted Weighted Outstanding at December 31, 2022 483 $ 3.83 1.3 Granted — — Vested ( 185 ) $ 4.06 Cancelled ( 51 ) $ 8.16 Outstanding at December 31, 2023 247 $ 3.58 0.8

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2023
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, 2023 (in thousands): Year Ending December 31, 2024 $ 294 Total lease payments 294 Less: imputed interest ( 12 ) Total operating lease liabilities $ 282
Schedule of Cash Flow Supplemental Disclosures	Other supplemental cash flow information consisted of the following: Year Ended 2023 2022 Cash paid for amounts included in the measurement of operating lease liabilities $ 0.4 $ 0.4 Other supplemental information, as of December 31, 2023 and 2022, consisted of the following: Year Ended 2023 2022 Weighted-average discount rate 14.8 % 8.0 % Weighted-average remaining lease term (in years) 0.7 0.7

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2023
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, 2023 and 2022 are detailed below (in thousands). Year Ended December 31, 2023 2022 Deferred tax assets: Federal and state net operating loss carryforwards $ 45,942 $ 41,179 Federal and California research and development credit carryforwards 11,987 9,058 Share-based compensation expense 2,297 1,899 Capitalized 59(e) Expenses and Amortization 3,274 3,829 Section 174 Capitalized R&D Expenditures 9,717 4,768 Other, net 57 52 Total deferred tax assets 73,274 60,785 ROU asset ( 58 ) ( 56 ) Total deferred tax liabilities ( 58 ) ( 56 ) Net deferred tax asset 73,216 60,729 Valuation allowance ( 73,216 ) ( 60,729 ) 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, 2023 and 2022 due to the following: Year Ended December 31, 2023 2022 % % Federal statutory rate 21 21 State tax benefit, net of federal benefit — — Valuation allowance ( 25 ) ( 23 ) General business credits 6 5 Other ( 2 ) ( 3 ) 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, 2023 2022 Gross unrecognized tax benefits at the beginning of the year $ 5,781 $ 4,962 Additions based on tax positions related to the current year 998 884 Reductions for tax positions of prior years — ( 65 ) Gross unrecognized tax benefits at the end of the year $ 6,779 $ 5,781

Organization and Basis of Pre_2

Organization and Basis of Presentation - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Nov. 04, 2021
Accumulated deficit	$ (265,932)	$ (214,874)
Working capital	16,600
Cash cash equivalents and short term investments	$ 53,700
Line of credit facility remaining			$ 45,000
Tranche Two [Member]
Line of credit facility remaining			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			45,000
Silicon Valley Bank ("SVB") and Oxford Finance LLC ("Oxford") [Member] | Tranche Two [Member]
Line of credit facility remaining			$ 20,000

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Summary of short-term investments measured at fair value on a recurring basis (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, Amortization cost	$ 51,399	$ 69,940
Debt securities, Unrealized gains	22	0
Debt securities, Unrealized losses	(13)	(178)
Debt securities	51,408	69,762
Cash and Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, Amortization cost	10,034	15,492
Debt securities, Unrealized gains	0	0
Debt securities, Unrealized losses	0	0
Debt securities	10,034	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	9,535	15,492
Debt securities, Unrealized gains	0	0
Debt securities, Unrealized losses	0	0
Debt securities	9,535	15,492
Cash and Cash Equivalents [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, Amortization cost	499
Debt securities, Unrealized gains	0
Debt securities, Unrealized losses	0
Debt securities	499
Short-Term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, Amortization cost	41,365	54,448
Debt securities, Unrealized gains	22	0
Debt securities, Unrealized losses	(13)	(178)
Debt securities	41,374	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	14,931	27,739
Debt securities, Unrealized gains	10	0
Debt securities, Unrealized losses	0	(34)
Debt securities	14,941	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	11,371	19,785
Debt securities, Unrealized gains	8	0
Debt securities, Unrealized losses	0	(109)
Debt securities	11,379	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	3,796	1,872
Debt securities, Unrealized gains	4	0
Debt securities, Unrealized losses	0	0
Debt securities	3,800	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	11,267	5,052
Debt securities, Unrealized gains	0	0
Debt securities, Unrealized losses	(13)	(35)
Debt securities	$ 11,254	$ 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, 2023	Dec. 31, 2022
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	10,034	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	9,535	15,492
Cash and Cash Equivalents [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	499
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	9,535	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	9,535	15,492
Cash and Cash Equivalents [Member] | Fair Value Level 1 [Member] | Commercial Paper [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]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	499	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	0
Cash and Cash Equivalents [Member] | Fair Value Level 2 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	499
Short-Term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	41,374	54,270
Total	51,408	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	14,941	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	11,379	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	3,800	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	11,254	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	11,379	19,676
Total	20,914	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	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	11,379	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	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	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	29,995	34,594
Total	30,494	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	14,941	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	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	3,800	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	$ 11,254	$ 5,017

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) Segment	Dec. 31, 2022 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, accrued interest receivable	$ 100	$ 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	$ 0
Third-party service, percentage	23.90%	23.20%
United States [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of reportable segment | Segment	1

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Summary of Antidilutive Securities Excluded From the Calculation of Weighted Average Dilutive Common Shares (Detail) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	9,933,755	8,079,190
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	9,596,644	7,751,573
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	21,212	11,718
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 ($) $ in Millions		12 Months Ended
	Mar. 22, 2021	Dec. 31, 2019	May 01, 2017
License Agreement Terms [Member]
Collaboration and License Agreements [Line Items]
Development milestone payment received		$ 3
DOT-1 License Agreement [Member] | License Vosaroxin [Member]
Collaboration and License Agreements [Line Items]
Regulatory, commercial milestones payments and double-digit royalty payments, receivable		57
DOT-1 License Agreement [Member] | License Agreement Terms [Member]
Collaboration and License Agreements [Line Items]
Potential pre-commercialization payments receivable		$ 57
Royalty Purchase Agreement [member]
Collaboration and License Agreements [Line Items]
Upfront payment received	$ 13.5
NK Agreement [Member]
Collaboration and License Agreements [Line Items]
Milestone payments to be received			$ 100

Financial Statement Details - P

Financial Statement Details - Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid expenses	$ 276	$ 780
ERC receivable	168	798
Prepaid insurance	581	567
Current deposits	135	442
Accrued interest receivable	113	112
Other	0	5
Total prepaid expenses and other current assets	$ 1,273	$ 2,704

Financial Statement Details -

Financial Statement Details - Schedule of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued payroll and benefits	$ 3,374	$ 2,961
Accrued clinical trial and contract expenses	6,456	3,562
Accrued professional services and expenses	258	385
Other accrued expenses	288	285
Total accrued expenses	$ 10,376	$ 7,193

Financial Statement Details - A

Financial Statement Details - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Employee Retention Credit [Member]
Tax Credit Carryforward [Line Items]
Other Assets, Current	$ 0.6	$ 0.8

Debt - Additional Information (

Debt - Additional Information (Detail) - USD ($) $ in Millions		12 Months Ended
	Nov. 04, 2021	Dec. 31, 2023
Debt [Line Items]
Line of credit facility remaining	$ 45
Line Of credit facility borrowing capacity description		The second tranche of $20.0 million was drawn by the Company on December 29, 2022. The availability of the additional tranche of $25.0 million, previously available under certain conditions, expired on December 31, 2023.
Debt Instrument, Interest Rate		13.40%
Tranche One [Member]
Debt [Line Items]
Line of credit facility remaining	20
Tranche Two [Member]
Debt [Line Items]
Line of credit facility remaining	25
Silicon Valley Bank [Member]
Debt [Line Items]
Repayments of Long-term Lines of Credit	5
Additional borrowing capacity		$ 25
Silicon Valley Bank ("SVB") and Oxford Finance LLC ("Oxford") [Member]
Debt [Line Items]
Line of credit maximum borrowing amount	50
Line of credit facility remaining	45
Silicon Valley Bank ("SVB") and Oxford Finance LLC ("Oxford") [Member] | Tranche Two [Member]
Debt [Line Items]
Line of credit facility remaining	$ 20
Term Loan Agreement [Member] | Silicon Valley Bank [Member]
Debt [Line Items]
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) $ in Thousands	Dec. 31, 2023 USD ($)
Debt Instrument [Line Items]
2024	$ 8,571
2025	8,571
2026	7,858
Total future principal payments	25,000
Final payment	397
Unamortized discount	(123)
Total, net	$ 25,274

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended		12 Months Ended
	May 28, 2021	Jan. 01, 2020	Jun. 30, 2022	Jan. 31, 2017	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jun. 30, 2021	Jul. 30, 2020
Stockholders Equity [Line Items]
Common stock, shares outstanding					39,093,509	38,345,140
Price per common share					$ 0.57	$ 1.46
Common Stock, Shares, Issued					39,093,509	38,345,140
Proceeds from Issuance of Common Stock					$ 299	$ 2,331
Convertible Preferred Stock, Shares Issued upon Conversion					18,811,552
Preferred stock, shares authorized					10,000,000	10,000,000
Preferred stock, shares outstanding					10,248	10,248
Weighted average grant date fair value per share					$ 1.17	$ 2.8
Common Stock, Shares Authorized					400,000,000	400,000,000
Weighted average exercise price					$ 4.35	$ 5.57
Stock reserved for future grant					11,381,684	9,717,600
Stock-based compensation					$ 7,649	$ 13,548
Stock option plan weighted average vesting period					8 years 3 months 18 days	8 years 9 months 18 days
Aggregate market value of common stock	$ 75,000
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					0
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%
Percentage of outstanding common stock							5%
2021 Inducement Plan [Member]
Stockholders Equity [Line Items]
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					$ 7,300	$ 11,200
Stock option plan weighted average vesting period					2 years 2 months 12 days
Unrecognised compensation expense related to unvested units					$ 10,900
Employee Stock Option Member | Chief Executive Officer [Member]
Stockholders Equity [Line Items]
NON RECURRING NON CASH EXPENSE						$ 4,000
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					246,853	483,282
Stock-based compensation					$ 200	$ 2,200
Unrecognised compensation expense related to unvested units					$ 300
Restricted Stock units plan weighted average vesting period					1 year 4 months 24 days
Restricted Stock Units [Member] | Chief Executive Officer [Member]
Stockholders Equity [Line Items]
NON RECURRING NON CASH EXPENSE						$ 1,600
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					$ 17.5
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
Stockholders Equity [Line Items]
Common Stock, Shares, Issued					371,675	564,125
Proceeds from Issuance of Common Stock					$ 300	$ 2,300
Share Issued					39,094	38,345	37,425
Weighted average exercise price					$ 0.83	$ 4.26
Proceeds from Issuance or Sale of Equity, Total					$ 47,300
Common Stock | 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					224,496
Shares Available for Future Grant					658,955
Purchase price of a share as a percentage of fair market value			85%
Duration of offering period			6 months
Share of common stock value			$ 25,000
Stock reserved for future grant					658,955	449,671
Stock-based compensation					$ 100
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

Stockholders' Equity - Shares o

Stockholders' Equity - Shares of Common Stock Reserved for Future Issuance (Detail) - shares	Dec. 31, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Total common stock reserved for future issuance	11,381,684	9,717,600
Authorized for future option grants [Member]
Class of Stock [Line Items]
Total common stock reserved for future issuance	723,977	1,114,248
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	658,955	449,671
Stock options issued and outstanding for all plans [Member]
Class of Stock [Line Items]
Total common stock reserved for future issuance	9,349,791	7,268,291
RSUs outstanding [Member]
Class of Stock [Line Items]
Total common stock reserved for future issuance	246,853	483,282
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, 2023	Dec. 31, 2022
Share Based Compensation Cost Included in Condensed Statement Of Operations [Line Items]
Total stock-based compensation expense	$ 7,649	$ 13,548
Research and development [Member]
Share Based Compensation Cost Included in Condensed Statement Of Operations [Line Items]
Total stock-based compensation expense	2,574	2,782
General and administrative [Member]
Share Based Compensation Cost Included in Condensed Statement Of Operations [Line Items]
Total stock-based compensation expense	$ 5,075	$ 10,766

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, 2023	Dec. 31, 2022	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	3.37%	1.82%	3.63%
Expected option term	5 years 9 months 18 days	5 years 6 months	3 years 7 months 6 days
Expected volatility of common stock	86.90%	82.70%	85.20%
Maximum [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Risk free interest rate	4.39%	3.97%	3.82%
Expected option term	6 years 3 months 18 days	6 years 3 months 18 days	6 years
Expected volatility of common stock	92.10%	86.20%	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, 2023	Dec. 31, 2022
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Outstanding, Beginning Balance, Number of Shares	7,201
Options granted , Numbers of Shares	3,176
Options exercised , Numbers of Shares	(17)
Options cancelled , Number of Shares	(1,010)
Outstanding, Ending Balance, Number of Shares	9,350	7,201
Vested and exercisable, Number of Shares	4,348
Outstanding and expected to vest, Number of Shares	9,350
Outstanding, Beginning Balance, Weighted Average Exercise Price Per Share	$ 5.57
Options granted, Weighted Average Exercise Price Per Share	1.55
Options exercised, Weighted Average Exercise Price Per Share	0.9
Options Cancelled , Weighted average exercise price	4.32
Outstanding, Ending Balance, Weighted Average Exercise Price Per Share	4.35	$ 5.57
Vested and excercise, Weighted Average Exercise Price	5.32
Outstanding and expected to vest, Weighted Average Exercise Price	$ 4.35
Outstanding, Weighted Average Remaining Contractual Term (Years)	8 years 3 months 18 days	8 years 9 months 18 days
Vested and exercisable, Weighted Average Remaining Contractual Term (Years)	7 years 8 months 12 days
Outstanding and expected to vest, Weighted Average Remaining Contractual Term (Years)	8 years 3 months 18 days
Outstanding beginning balance, Aggregate Intrinsic Value	$ 208
Exercised, Aggregate Intrinsic Value	18
Outstanding ending balance, Aggregate Intrinsic Value	1	$ 208
Vested and exercisable, Aggregate Intrinsic Value	0
Outstanding and expected to vest , Aggregate Intrinsic Value	$ 1

Stockholders' Equity - Summar_4

Stockholders' Equity - Summary of Restricted Stock Units Activity (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]
RSUs, Beginning balance	483
Granted	0
Vested	(185)
Cancelled	(51)
RSUs, Ending balance	247	483
Weighted Average Grant Date Fair Value per Share, Beginning balance	$ 3.83
Weighted Average Grant Date Fair Value per Share, Granted	0
Weighted Average Grant Date Fair Value per Share, Vested	4.06
Weighted Average Grant Date Fair Value per Share, Cancelled	8.16
Weighted Average Grant Date Fair Value per Share, Ending balance	$ 3.58	$ 3.83
Weighted Average Remaining Contractual Term (Years)	9 months 18 days	1 year 3 months 18 days

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($)		1 Months Ended	12 Months Ended
	Aug. 31, 2020	Jun. 30, 2020	Dec. 31, 2023	Dec. 31, 2022
Loss Contingencies [Line Items]
Lease liability			$ 282,000
Operating lease right-of-use asset			274,000	$ 266,000
Operating Lease Expense			400,000	400,000
Cash paid for amounts included in the measurement of operating lease liabilities			400	$ 400
Lessee, Operating Lease, Option to Extend		option for an additional year
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		$ 200,000
Percentage of increase in monthly base rent		4%
Lessee, Operating Lease, Description		August 2023
Additional noncancelable operating lease agreement [Member] | New Operating Lease [Member]
Loss Contingencies [Line Items]
Operating lease right-of-use asset	$ 200,000
Lessee, Operating Lease, Description	August 2020 through 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
Maximum [Member] | Noncancelable operating lease agreement [Member] | Amended Operating Lease [Member]
Loss Contingencies [Line Items]
Operating leases rent expense		$ 22,195,000
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	$ 14,524,000
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, 2023 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2024	$ 294
Total lease payments	294
Less: imputed interest	(12)
Total operating lease liabilities	$ 282

Commitments and Contingencies_3

Commitments and Contingencies - Schedule of Cash Flow Supplemental Disclosures (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Supplemental Cash Flow Information [Abstract]
Cash paid for amounts included in the measurement of operating lease liabilities	$ 400	$ 400
weighted average discount rate	14.80%	8%
weighted average remaining lease term (in years)	8 months 12 days	8 months 12 days

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Operating Loss Carryforwards [Line Items]
Income tax provision	$ 0	$ 0
Statutory income tax rate	21%	21%
Net valuation allowance, increased (decreased)	$ 12.5	$ 11.3
Orphan drug credit carryforwards	13.6
Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carry-forwards	188.2
Research and development tax credit carry-forwards	$ 1.5
Net operating loss carry-forwards expiration	2027
Operating loss carryforwards, not subject to expiration	$ 147.9
Research credit carryforwards expiration start year	2027
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carry-forwards	$ 106.6
Research and development tax credit carry-forwards	$ 2.7
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, 2023	Dec. 31, 2022
Deferred Tax Assets, Net [Abstract]
Federal and state net operating loss carryforwards	$ 45,942	$ 41,179
Federal and California research and development credit carryforwards	11,987	9,058
Share-based compensation expense	2,297	1,899
Capitalized 59(e) Expenses and Amortization	3,274	3,829
Section 174 Capitalized R&D Expenditures	9,717	4,768
Other, net	57	52
Total deferred tax assets	73,274	60,785
ROU asset	(58)	(56)
Total deferred tax liabilities	(58)	(56)
Net deferred tax asset	73,216	60,729
Valuation allowance	(73,216)	(60,729)
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, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Federal statutory rate	21%	21%
State tax benefit, net of federal benefit	0%	0%
Valuation allowance	(25.00%)	(23.00%)
General business credits	6%	5%
Other	(2.00%)	(3.00%)
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, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Gross unrecognized tax benefits at the beginning of the year	$ 5,781	$ 4,962
Additions based on tax positions related to the current year	998	884
Reductions for tax positions of prior years	0	(65)
Gross unrecognized tax benefits at the end of the year	$ 6,779	$ 5,781

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Subsequent Event [Line Items]
Final payment	$ 397