Viracta Therapeutics (VIRX) 10-Q 9 May 24 2024 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2024	May 06, 2024
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
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 Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	false
Securities Act File Number	000-51531
Entity Tax Identification Number	94-3295878
Entity Address, Address Line One	2533 S. Coast Hwy. 101, Suite 210
Entity Address, City or Town	Cardiff
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92007
City Area Code	858
Local Phone Number	400-8470
Document Quarterly Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
Entity Incorporation, State or Country Code	DE
Trading Symbol	VIRX
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Security Exchange Name	NASDAQ

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Current Assets:
Cash and cash equivalents	$ 12,062	$ 12,317
Short-term investments	27,504	41,374
Prepaid expenses and other current assets	1,386	1,273
Total current assets	40,952	54,964
Property and equipment, net	163	190
Operating lease right-of-use asset	175	274
Other assets	44	1,264
Total assets	41,334	56,692
Current Liabilities:
Accounts payable	2,412	2,441
Accrued expenses	8,985	10,376
Operating lease liabilities	179	282
Debt, net	18,678	25,274
Total current liabilities	30,254	38,373
Total liabilities	30,254	38,373
Commitments and contingencies (Note 7)
Stockholders' equity:
Convertible preferred stock, $0.0001 par value; 10,000,000 shares authorized as of March 31, 2024; 10,248 shares issued and outstanding as of March 31, 2024 and December 31, 2023	5,452	5,452
Common stock, $0.0001 par value; 400,000,000 shares authorized; 39,272,434 and 39,093,509 shares issued and outstanding at March 31, 2024 and December 31, 2023, respectively	4	4
Additional paid-in capital	280,703	278,786
Accumulated other comprehensive income (loss)	(6)	9
Accumulated deficit	(275,073)	(265,932)
Total stockholders' equity	11,080	18,319
Total liabilities and stockholders' equity	$ 41,334	$ 56,692

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited) - $ / shares	Mar. 31, 2024	Dec. 31, 2023
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	39,272,434	39,093,509
Common stock, shares outstanding	39,272,434	39,093,509

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating expenses:
Research and development	$ 9,956	$ 7,607
General and administrative	3,920	4,600
Total operating expenses	13,876	12,207
Loss from operations	(13,876)	(12,207)
Other income (expense):
Interest income	592	878
Interest expense	(858)	(880)
Realized gain on investments	1	0
Other income	5,000	0
Total other income (expense)	4,735	(2)
Net loss	(9,141)	(12,209)
Unrealized gain (loss) on short-term investments	(15)	91
Comprehensive loss	$ (9,156)	$ (12,118)
Net loss per share of common stock, basic	$ (0.23)	$ (0.32)
Net loss per share of common stock, diluted	$ (0.23)	$ (0.32)
Weighted-average shares used to compute basic net loss per share	39,323,964	38,458,837
Weighted-average shares used to compute diluted net loss per share	39,323,964	38,458,837

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Preferred Stock [Member] Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]
Beginning balance at Dec. 31, 2022	$ 61,103	$ 5,452	$ 4	$ 270,699	$ (178)	$ (214,874)
Beginning balance, shares at Dec. 31, 2022		10	38,345
Issuance of common stock upon exercise of stock options and from employee stock plan	16			16
Issuance of common stock upon exercise of stock options and from employee stock plan, shares			18
Issuance of common stock upon vesting of restricted stock units			48
Share-based compensation	2,112			2,112
Unrealized gain (loss) on short-term investments	91				91
Net loss	(12,209)					(12,209)
Ending balance at Mar. 31, 2023	51,113	$ 5,452	$ 4	272,827	(87)	(227,083)
Ending balance, shares at Mar. 31, 2023		10	38,411
Beginning balance at Dec. 31, 2023	18,319	$ 5,452	$ 4	278,786	9	(265,932)
Beginning balance, shares at Dec. 31, 2023		10	39,094
Issuance of common stock through "at the market" offering, net	80			80
Issuance of common stock through "at the market" offering, net, shares			138
Issuance of common stock upon vesting of restricted stock units			40
Share-based compensation	1,837			1,837
Unrealized gain (loss) on short-term investments	(15)				(15)
Net loss	(9,141)					(9,141)
Ending balance at Mar. 31, 2024	$ 11,080	$ 5,452	$ 4	$ 280,703	$ (6)	$ (275,073)
Ending balance, shares at Mar. 31, 2024		10	39,272

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating activities
Net loss	$ (9,141)	$ (12,209)
Adjustments to reconcile net loss to net cash used in by operating activities:
Share-based compensation expense	1,837	2,112
Depreciation and amortization	110	122
Amortization of premiums and accretion of discounts on short-term investments, net	(337)	(523)
Change in operating assets and liabilities:
Prepaid expenses and other assets	(114)	(379)
Other assets	1,220	142
Accounts payable	(30)	(459)
Accrued expenses	(1,391)	(146)
Lease liabilities, net	(3)	0
Net cash used in operating activities	(7,849)	(11,340)
Investing activities
Purchases of short-term investments	(6,057)	(27,622)
Proceeds from maturity of short-term investments	20,249	20,272
Net cash provided by (used in) investing activities	14,192	(7,350)
Financing activities
Issuance of common stock, net of issuance costs	80	0
Issuance of common stock upon option exercises and from employee stock plan	0	16
Payments on borrowings of debt	(6,678)	0
Net cash provided by (used in) financing activities	(6,598)	16
Net decrease in cash and cash equivalents	(255)	(18,674)
Cash and cash equivalents at beginning of period	12,317	36,773
Cash and cash equivalents at end of period	12,062	18,099
Supplemental disclosure of cash flow information
Interest paid	851	579
Interest received	613	878
Supplemental disclosure of noncash activities
Operating lease right-of-use assets obtained in exchange for operating lease liabilities	$ 0	$ 381

Organization and Basis of Prese

Organization and Basis of Presentation	3 Months Ended
	Mar. 31, 2024
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 March 31, 2024, 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 March 31, 2024, had an accumulated deficit of $ 275.1 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 March 31, 2024, the Company had cash, cash equivalents, and short-term investments of $ 39.6 million and working capital of $ 10.7 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 condensed 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 March 31, 2024 . The accompanying condensed 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.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2024
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation and Principles of Consolidation The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries and have been prepared in accordance with GAAP and follow the requirements of the U.S. Securities and Exchange Commission (“SEC”) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by GAAP can be condensed or omitted. In management’s opinion, the unaudited interim financial statements have been prepared on the same basis as the audited financial statements and include all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of the Company’s financial position and its results of operations and its cash flows for the periods presented. These statements do not include all disclosures required by GAAP and should be read in conjunction with the Company’s financial statements and accompanying notes for the year ended December 31, 2023 , which are contained in the Company’s Current Report on Form 10-K filed with the SEC on March 7, 2024. The results for interim periods are not necessarily indicative of the results expected for the full fiscal year or any other interim period. Significant Accounting Policies A description of the Company’s significant accounting policies is included in the audited consolidated financial statements within its Annual Report on Form 10-K for the year ended December 31, 2023. Except as noted below, there have been no material changes in the Company’s significant accounting policies during the three months ended March 31, 2024 . 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 and such deposits are 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 laboratories 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 three months ended March 31, 2024 and 2023 , the Company had two contract laboratories that provided 41.9 % and one contract laboratory that provided 10.9 % of total third-party services, r espectively . Use of Estimates The preparation of condensed 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 condensed consolidated financial statements and the reported amounts of expenses during the reporting period. Actual results could differ materially from those estimates. 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 unaudited condensed consolidated balance sheets. The following tables summarize, 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 March 31, 2024 and December 31, 2023, in thousands: March 31, 2024 Maturities Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash equivalents: Money market funds 1 or less $ 9,839 $ — $ — $ 9,839 Total cash equivalents 9,839 — — 9,839 Short-term investments: U.S. Treasury securities 1 or less 8,254 — ( 2 ) 8,252 Commercial paper 1 or less 13,087 — ( 1 ) 13,086 Corporate debt securities 2 or less 3,378 1 — 3,379 U.S. Agency bonds 1 or less 2,791 — ( 4 ) 2,787 Total short-term investments 27,510 1 ( 7 ) 27,504 Total $ 37,349 $ 1 $ ( 7 ) $ 37,343 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 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 March 31, 2024, 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 March 31, 2024, 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 March 31, 2024 and December 31, 2023. Accrued interest receivable on available-for-sale securities was $ 0.1 million at March 31, 2024 and December 31, 2023 . We have no t written off any accrued interest receivables for the three months ended March 31, 2024 and 2023. 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. Below is a summary of assets, including cash equivalents and short-term investments, measured at fair value as of March 31, 2024 and December 31, 2023, in thousands. Fair Value Measurements Using March 31, 2024 Level 1 Level 2 Cash equivalents: Money market funds $ 9,839 $ 9,839 $ — Total cash equivalents 9,839 9,839 — Short-term investments: U.S. Treasury securities 8,252 8,252 — Commercial paper 13,086 — 13,086 Corporate debt securities 3,379 — 3,379 U.S. Agency bonds 2,787 — 2,787 Total short-term investments 27,504 8,252 19,252 Total $ 37,343 $ 18,091 $ 19,252 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 The Company had no liabilities measured at fair value on a recurring basis a s of March 31, 2024 and December 31, 2023 . 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 common stock equivalent securities are excluded from the calculation of weighted average dilutive common shares because their inclusion would have been anti-dilutive: March 31, 2024 2023 Shares issuable upon conversion of preferred stock 292,799 292,799 Common stock options and RSUs outstanding 11,606,919 9,560,329 ESPP shares pending issuance 84,807 37,619 Warrants to purchase common stock 23,100 23,100 Total excluded securities 12,007,625 9,913,847 Recently Issued Accounting Pronouncements In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures . The ASU amendments are intended to improve reportable segment disclosure, primarily through enhanced disclosures about significant segment expenses. This guidance is effective for annual periods beginning after December 15, 2023, and interim periods beginning after December 15, 2024. The amendments in this ASU should be applied retrospectively to all prior periods presented in the financial statements. Early adoption is permitted. The Company is currently evaluating the impact of this guidance on its financial statements and related disclosures.

Collaboration and License Agree

Collaboration and License Agreements	3 Months Ended
	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaboration and License Agreements	3. Collaboration and License Agreements 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 (as defined below). Also in December 2019, the Company entered into an agreement to license vosaroxin to Denovo Biopharma LLC (“Denovo”), which includes up to $ 57.0 million in potential regulatory and commercial milestones, and double-digit royalties on future sales of vosaroxin, when and if approved and commercialized. The potential milestone and royalty payments related to DAY101 and vosaroxin were sold in the XOMA Transaction. On 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 the Day One license agreement and the Denovo license agreement, each as described above (the “XOMA Transaction”). The Company received, and recorded as a gain in the statement of operations and comprehensive loss for 2021, an upfront payment of $ 13.5 million, and retained a pre-commercialization, event-based milestone. On March 4, 2024, the Company entered into an Amendment No. 1 (the “Day One Amendment”) to the license agreement with Day One to monetize a pre-commercialization, event-based milestone for $ 5.0 million, thereby reducing the milestone percentage under the agreement. Also 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 with XOMA 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 future pre-commercialization, event-based milestone up to $ 5.0 million. Pursuant to the Day One Amendment, the Company received and recorded $ 5.0 million as other income in the condensed consolidated statement of operations and comprehensive loss for the three months ended March 31, 2024 .

Financial Statement Details

Financial Statement Details	3 Months Ended
	Mar. 31, 2024
Financial Statement Details [Abstract]
Financial Statement Details	4. Financial Statement Details Accrued Expenses Accrued expenses consist of the following (in thousands): March 31, December 31, 2024 2023 Accrued payroll and benefits $ 1,219 $ 3,374 Accrued clinical trial and contract expenses 7,218 6,456 Accrued professional services and expenses 336 258 Other accrued expenses 212 288 Total accrued expenses $ 8,985 $ 10,376

Debt

Debt	3 Months Ended
	Mar. 31, 2024
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 was scheduled to be followed by 35 equal monthly payments of principal plus accrued interest commencing on January 1, 2024, but was modified pursuant to the Second Amendment to the SVB-Oxford Loan Facility entered into on March 1, 2024 (the “Second Amendment”). The Second Amendment provides 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, we remitted a prepayment of $5.0 million toward the outstanding principal as of March 31, 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. The per annum interest rate for any outstanding loan is equal to the greater of (i) 8.15 % and (ii) the sum of (a) the Prime Rate, as reported in The Wall Street Journal on the last business day of the month that immediately precedes the month in which the interest will accrue, plus (b) 4.90 %. As of March 31, 2024, 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 March 31, 2024, 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 March 31, 2024. The following table summarizes future principal payments, including the final payment, under the terms of the SVB-Oxford Loan Facility as of March 31, 2024 (in thousands): Years Ending December 31, 2024 (remaining) $ 3,842 2025 7,685 2026 7,044 Total future principal payments 18,571 Final payment, net of unamortized prepayment 219 Unamortized discount ( 112 ) Total, net $ 18,678

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2024
Stockholders' Equity Note [Abstract]
Stockholders' Equity	6. Stockholders’ Equity Sale 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 of shares (the “Shares”) of its common stock, par value $ 0.0001 per share, 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 three months ended March 31, 2024, the Company sold 137,783 shares of its common stock pursuant to the Sale Agreement at a weighted average price per share of $ 0.60 for $ 0.1 million, net of commissions. The Company did not sell any Shares pursuant to the Sale Agreement during the three months ended March 31, 2023. As of March 31, 2024, the Company had approximately $ 47.2 million available under the Sale Agreement, subject to the limitations described above pursuant to General Instruction I.B.6 of Form S-3. 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 stoc k. There were 10,248 shares of this preferred stock outstanding as of March 31, 2024 , of which 1,915 shares were Series E Stock and 8,333 shares were Series F Stock. The Series E Stock and Series F Stock are non-voting Series E and Series F Convertible Preferred Stock at a stated price of $ 500 and $ 600 per share, respectively. Each share of non-voting Series E Stock and Series F Stock is convertible at a conversion ratio equal to the stated price divided by the conversion price, which is $ 17.50 per share and $ 21.00 per share, respectively, provided that conversion will be prohibited if, as a result, the holder and its affiliates would own more than 9.98 % of the total number of shares of common stock then outstanding. In the event of the Company’s liquidation, dissolution, or winding up, holders of Series E and Series F Stock will receive a payment 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. Share-Based Compensation The share-based compensation cost recorded in the accompanying condensed consolidated statements of operations is presented below (in thousands): Three Months Ended March 31, 2024 2023 Research and development $ 625 $ 741 General and administrative 1,212 1,371 Total $ 1,837 $ 2,112 As of March 31, 2024, unrecognized compensation expense related to unvested options granted and unvested RSUs totaled $ 10.1 million and $ 0.1 million, respectively. The expense for unvested stock options and RSUs is expected to be recognized over a weighted-average period of 2.3 and 1.2 years, respectively.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2024
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 March 31, 2024 (in thousands): Year Ending December 31, 2024 $ 184 Total lease payments 184 Less: imputed interest ( 5 ) Total operating lease liabilities $ 179 Other supplemental cash flow information consisted of the following: Three Months Ended 2024 2023 Cash paid for amounts included in the measurement of operating lease liabilities $ 0.1 $ 0.1 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. During the quarter ended March 31, 2024, the Company determined that the retrospective insurance policy recorded as an asset upon the Merger on February 24, 2021, should have been expensed by Sunesis prior to the Merger. Consequently, for the three months ended March 31, 2024, the Company recorded an immaterial non-cash error correction to eliminate the remaining prepaid retrospective insurance policy asset with a corresponding increase to research and development expense in the amount of $ 1.8 million .

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2024
Accounting Policies [Abstract]
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries and have been prepared in accordance with GAAP and follow the requirements of the U.S. Securities and Exchange Commission (“SEC”) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by GAAP can be condensed or omitted. In management’s opinion, the unaudited interim financial statements have been prepared on the same basis as the audited financial statements and include all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of the Company’s financial position and its results of operations and its cash flows for the periods presented. These statements do not include all disclosures required by GAAP and should be read in conjunction with the Company’s financial statements and accompanying notes for the year ended December 31, 2023 , which are contained in the Company’s Current Report on Form 10-K filed with the SEC on March 7, 2024. The results for interim periods are not necessarily indicative of the results expected for the full fiscal year or any other interim period.
Significant Accounting Policies	Significant Accounting Policies A description of the Company’s significant accounting policies is included in the audited consolidated financial statements within its Annual Report on Form 10-K for the year ended December 31, 2023. Except as noted below, there have been no material changes in the Company’s significant accounting policies during the three months ended March 31, 2024 .
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 and such deposits are 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 laboratories 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 three months ended March 31, 2024 and 2023 , the Company had two contract laboratories that provided 41.9 % and one contract laboratory that provided 10.9 % of total third-party services, r espectively
Use of Estimates	Use of Estimates The preparation of condensed 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 condensed consolidated financial statements and the reported amounts of expenses during the reporting period. Actual results could differ materially from those estimates.
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 unaudited condensed consolidated balance sheets. The following tables summarize, 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 March 31, 2024 and December 31, 2023, in thousands: March 31, 2024 Maturities Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash equivalents: Money market funds 1 or less $ 9,839 $ — $ — $ 9,839 Total cash equivalents 9,839 — — 9,839 Short-term investments: U.S. Treasury securities 1 or less 8,254 — ( 2 ) 8,252 Commercial paper 1 or less 13,087 — ( 1 ) 13,086 Corporate debt securities 2 or less 3,378 1 — 3,379 U.S. Agency bonds 1 or less 2,791 — ( 4 ) 2,787 Total short-term investments 27,510 1 ( 7 ) 27,504 Total $ 37,349 $ 1 $ ( 7 ) $ 37,343 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 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 March 31, 2024, 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 March 31, 2024, 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 March 31, 2024 and December 31, 2023. Accrued interest receivable on available-for-sale securities was $ 0.1 million at March 31, 2024 and December 31, 2023 . We have no t written off any accrued interest receivables for the three months ended March 31, 2024 and 2023. 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. Below is a summary of assets, including cash equivalents and short-term investments, measured at fair value as of March 31, 2024 and December 31, 2023, in thousands. Fair Value Measurements Using March 31, 2024 Level 1 Level 2 Cash equivalents: Money market funds $ 9,839 $ 9,839 $ — Total cash equivalents 9,839 9,839 — Short-term investments: U.S. Treasury securities 8,252 8,252 — Commercial paper 13,086 — 13,086 Corporate debt securities 3,379 — 3,379 U.S. Agency bonds 2,787 — 2,787 Total short-term investments 27,504 8,252 19,252 Total $ 37,343 $ 18,091 $ 19,252 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 The Company had no liabilities measured at fair value on a recurring basis a s of March 31, 2024 and December 31, 2023 .
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 common stock equivalent securities are excluded from the calculation of weighted average dilutive common shares because their inclusion would have been anti-dilutive: March 31, 2024 2023 Shares issuable upon conversion of preferred stock 292,799 292,799 Common stock options and RSUs outstanding 11,606,919 9,560,329 ESPP shares pending issuance 84,807 37,619 Warrants to purchase common stock 23,100 23,100 Total excluded securities 12,007,625 9,913,847
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures . The ASU amendments are intended to improve reportable segment disclosure, primarily through enhanced disclosures about significant segment expenses. This guidance is effective for annual periods beginning after December 15, 2023, and interim periods beginning after December 15, 2024. The amendments in this ASU should be applied retrospectively to all prior periods presented in the financial statements. Early adoption is permitted. The Company is currently evaluating the impact of this guidance on its financial statements and related disclosures.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2024
Accounting Policies [Abstract]
Summary of short-term investments measured at fair value on a recurring basis	The following tables summarize, 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 March 31, 2024 and December 31, 2023, in thousands: March 31, 2024 Maturities Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash equivalents: Money market funds 1 or less $ 9,839 $ — $ — $ 9,839 Total cash equivalents 9,839 — — 9,839 Short-term investments: U.S. Treasury securities 1 or less 8,254 — ( 2 ) 8,252 Commercial paper 1 or less 13,087 — ( 1 ) 13,086 Corporate debt securities 2 or less 3,378 1 — 3,379 U.S. Agency bonds 1 or less 2,791 — ( 4 ) 2,787 Total short-term investments 27,510 1 ( 7 ) 27,504 Total $ 37,349 $ 1 $ ( 7 ) $ 37,343 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
Summary of assets including cash equivalents and marketable securities, measured at fair value	Below is a summary of assets, including cash equivalents and short-term investments, measured at fair value as of March 31, 2024 and December 31, 2023, in thousands. Fair Value Measurements Using March 31, 2024 Level 1 Level 2 Cash equivalents: Money market funds $ 9,839 $ 9,839 $ — Total cash equivalents 9,839 9,839 — Short-term investments: U.S. Treasury securities 8,252 8,252 — Commercial paper 13,086 — 13,086 Corporate debt securities 3,379 — 3,379 U.S. Agency bonds 2,787 — 2,787 Total short-term investments 27,504 8,252 19,252 Total $ 37,343 $ 18,091 $ 19,252 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 The Company had no liabilities measured at fair value on a recurring basis a
Summary of antidilutive securities excluded from the calculation of weighted average dilutive common shares	The following common stock equivalent securities are excluded from the calculation of weighted average dilutive common shares because their inclusion would have been anti-dilutive: March 31, 2024 2023 Shares issuable upon conversion of preferred stock 292,799 292,799 Common stock options and RSUs outstanding 11,606,919 9,560,329 ESPP shares pending issuance 84,807 37,619 Warrants to purchase common stock 23,100 23,100 Total excluded securities 12,007,625 9,913,847

Financial Statement Details (Ta

Financial Statement Details (Tables)	3 Months Ended
	Mar. 31, 2024
Financial Statement Details [Abstract]
Schedule of Accrued Liabilities	Accrued expenses consist of the following (in thousands): March 31, December 31, 2024 2023 Accrued payroll and benefits $ 1,219 $ 3,374 Accrued clinical trial and contract expenses 7,218 6,456 Accrued professional services and expenses 336 258 Other accrued expenses 212 288 Total accrued expenses $ 8,985 $ 10,376

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2024
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 March 31, 2024 (in thousands): Years Ending December 31, 2024 (remaining) $ 3,842 2025 7,685 2026 7,044 Total future principal payments 18,571 Final payment, net of unamortized prepayment 219 Unamortized discount ( 112 ) Total, net $ 18,678

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2024
Stockholders' Equity Note [Abstract]
Summary of Shared Based Compensation Cost Included in Condensed Statement Of Operations	The share-based compensation cost recorded in the accompanying condensed consolidated statements of operations is presented below (in thousands): Three Months Ended March 31, 2024 2023 Research and development $ 625 $ 741 General and administrative 1,212 1,371 Total $ 1,837 $ 2,112

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases	The following table summarizes future minimum payments under the Company's operating leases as of March 31, 2024 (in thousands): Year Ending December 31, 2024 $ 184 Total lease payments 184 Less: imputed interest ( 5 ) Total operating lease liabilities $ 179
Schedule of Cash Flow Supplemental Disclosures	Other supplemental cash flow information consisted of the following: Three Months Ended 2024 2023 Cash paid for amounts included in the measurement of operating lease liabilities $ 0.1 $ 0.1

Organization and Basis of Pre_2

Organization and Basis of Presentation - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Nov. 04, 2021
Accumulated deficit	$ (275,073)		$ (265,932)
Cash cash equivalents and short term investments	39,600
Working capital	$ 10,700
Line of credit facility, remaining borrowing capacity				$ 45,000
Third Party Service Percentage	41.90%	10.90%
Silicon Valley Bank ("SVB") and Oxford Finance LLC ("Oxford") [Member]
Line of Credit Facility, Additional Borrowing Capacity			$ 25,000
Line of credit facility, maximum borrowing capacity				50,000
Line of credit facility, current borrowing capacity				5,000
Line of credit facility, remaining borrowing capacity				45,000
Tranche Two [Member]
Line of credit facility, remaining borrowing capacity				25,000
Tranche Two [Member] | Silicon Valley Bank ("SVB") and Oxford Finance LLC ("Oxford") [Member]
Line of credit facility, remaining borrowing capacity				$ 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 (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, Amortization cost	$ 37,349	$ 51,399
Debt securities, Unrealized gains	1	22
Debt securities, Unrealized losses	(7)	(13)
Debt securities	37,343	51,408
Cash and Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, Amortization cost	9,839	10,034
Debt securities, Unrealized gains	0	0
Debt securities, Unrealized losses	0	0
Debt securities	9,839	10,034
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	9,839	9,535
Debt securities, Unrealized gains	0	0
Debt securities, Unrealized losses	0	0
Debt securities	9,839	9,535
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		499
Short-Term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, Amortization cost	27,510	41,365
Debt securities, Unrealized gains	1	22
Debt securities, Unrealized losses	(7)	(13)
Debt securities	27,504	41,374
Short-Term Investments [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, Amortization cost	13,087	14,931
Debt securities, Unrealized gains	0	10
Debt securities, Unrealized losses	(1)	0
Debt securities	13,086	14,941
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	8,254	11,371
Debt securities, Unrealized gains	0	8
Debt securities, Unrealized losses	(2)	0
Debt securities	8,252	11,379
Short-Term Investments [Member] | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, Amortization cost	3,378	3,796
Debt securities, Unrealized gains	1	4
Debt securities, Unrealized losses	0	0
Debt securities	3,379	3,800
Short-Term Investments [Member] | U.S. Agency bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, Amortization cost	2,791	11,267
Debt securities, Unrealized gains	0	0
Debt securities, Unrealized losses	(4)	(13)
Debt securities	$ 2,787	$ 11,254

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Summary of assets including cash equivalents and marketable securities, measured at fair value (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
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	9,839	10,034
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	9,839	9,535
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] | US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	8,252
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	9,839	9,535
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	9,839	9,535
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 1 [Member] | US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	8,252
Cash and Cash Equivalents [Member] | Fair Value Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	0	499
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
Cash and Cash Equivalents [Member] | Fair Value Level 2 [Member] | US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	0
Short-Term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	27,504	41,374
Total	37,343	51,408
Short-Term Investments [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	13,086	14,941
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
Short-Term Investments [Member] | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	3,379	3,800
Short-Term Investments [Member] | U.S. Agency bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	2,787	11,254
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	8,252	11,379
Total	18,091	20,914
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
Short-Term Investments [Member] | Fair Value Level 1 [Member] | Corporate debt securities
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
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	19,252	29,995
Total	19,252	30,494
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	13,086	14,941
Short-Term Investments [Member] | Fair Value Level 2 [Member] | US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments		0
Short-Term Investments [Member] | Fair Value Level 2 [Member] | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	3,379	3,800
Short-Term Investments [Member] | Fair Value Level 2 [Member] | U.S. Agency bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Short-term investments	$ 2,787	$ 11,254

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities measured at fair value on recurring basis	$ 0		$ 0
Available-for-sale securities	Other assets
Available-for-sale securities, Accrued interest receivable	$ 100		$ 100
Available-for-sale, Accrued interest writeoff	$ 0	$ 0

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	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	12,007,625	9,913,847
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	11,606,919	9,560,329
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	84,807	37,619
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		3 Months Ended	12 Months Ended
	Mar. 22, 2021	Mar. 31, 2024	Dec. 31, 2019	Mar. 04, 2024
License Agreement Terms [Member]
Related Party Transaction [Line Items]
Development milestone payment received			$ 3
Royalty Purchase Agreement [Member]
Related Party Transaction [Line Items]
Upfront payment received	$ 13.5
DOT-1 License Agreement [Member] | License Vosaroxin [Member]
Related Party Transaction [Line Items]
Regulatory, commercial milestones payments and double-digit royalty payments, receivable			57
DOT-1 License Agreement [Member] | License Agreement Terms [Member]
Related Party Transaction [Line Items]
Potential pre-commercialization payments receivable			$ 57
Day One Amendment [Member] | License Agreement Terms [Member]
Related Party Transaction [Line Items]
Regulatory, commercial milestones payments and double-digit royalty payments, receivable				$ 5
Milestone payments received		$ 5
Day One Amendment [Member] | Maximum [Member] | License Agreement Terms [Member]
Related Party Transaction [Line Items]
Regulatory, commercial milestones payments and double-digit royalty payments, receivable				$ 5

Financial Statement Details -

Financial Statement Details - Schedule of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Payables and Accruals [Abstract]
Accrued payroll and benefits	$ 1,219	$ 3,374
Accrued clinical trial and contract expenses	7,218	6,456
Accrued professional services and expenses	336	258
Other accrued expenses	212	288
Total accrued expenses	$ 8,985	$ 10,376

XOMA Transaction - Additional i

XOMA Transaction - Additional information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
License Agreement Terms [Member]
Development milestone payment received	$ 3

Debt - Additional Information (

Debt - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended
	Nov. 04, 2021	Mar. 31, 2024
Debt [Line Items]
Line of credit facility, remaining borrowing capacity	$ 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%
Silicon Valley Bank ("SVB") and Oxford Finance LLC ("Oxford") [Member]
Debt [Line Items]
Line of credit facility, maximum borrowing capacity	50
Silicon Valley Bank [Member]
Debt [Line Items]
Repayments of long-term lines of credit	5
Tranche One [Member]
Debt [Line Items]
Line of credit facility, remaining borrowing capacity	20
Tranche Two [Member]
Debt [Line Items]
Line of credit facility, remaining borrowing capacity	$ 25
Term Loan Agreement [Member] | Silicon Valley Bank [Member]
Debt [Line Items]
Debt instrument, maturity date		Nov. 01, 2026
Debt instrument, interest rate		4.90%
Debt instrument final payment interest fee percentage		5%
Term Loan Agreement [Member] | Silicon Valley Bank [Member] | Prime Rate [Member]
Debt [Line Items]
Debt instrument, interest rate during period		8.15%

Debt - Summary of Future Minimu

Debt - Summary of Future Minimum Payments Under Loan Facility (Detail) $ in Thousands	Mar. 31, 2024 USD ($)
Debt Instrument [Line Items]
2024 (remaining)	$ 3,842
2025	7,685
2026	7,044
Total future principal payments	18,571
Final payment, net of unamortized prepayment	219
Unamortized discount	(112)
Total, net	$ 18,678

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
	May 28, 2021	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Stockholders Equity [Line Items]
Common stock, shares outstanding		39,272,434		39,093,509
Proceeds from issuance of common stock		$ 80	$ 0
Convertible preferred stock, shares issued upon conversion		18,811,552
Preferred stock, shares authorized		10,000,000		10,000,000
Common stock, shares issued		39,272,434		39,093,509
Preferred stock, shares outstanding		10,248		10,248
Aggregate market value of common stock	$ 75,000
Restricted Stock Units [Member]
Stockholders Equity [Line Items]
Unrecognised compensation expense related to unvested units		$ 100
Restricted Stock units plan weighted average vesting period		1 year 2 months 12 days
Employee Stock Option [Member]
Stockholders Equity [Line Items]
Stock option plan weighted average vesting period		2 years 3 months 18 days
Unrecognised compensation expense related to unvested units		$ 10,100
Series E and Series F Convertible Preferred Stock [Member]
Stockholders Equity [Line Items]
Percentage of outstanding common stock		9.98%
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
Common Stock [Member]
Stockholders Equity [Line Items]
Proceeds from issuance of common stock		$ 100
Common stock, shares issued		137,783
Receivable from sale of common stock		$ 47,200
Weighted average exercise price		$ 0.6
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 - Summary

Stockholders' Equity - Summary of Shared Based Compensation Cost Included in Condensed Statement Of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Share Based Compensation Cost Included in Condensed Statement Of Operations [Line Items]
Total stock-based compensation expense	$ 1,837	$ 2,112
Research and development [Member]
Share Based Compensation Cost Included in Condensed Statement Of Operations [Line Items]
Total stock-based compensation expense	625	741
General and administrative [Member]
Share Based Compensation Cost Included in Condensed Statement Of Operations [Line Items]
Total stock-based compensation expense	$ 1,212	$ 1,371

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($)		1 Months Ended	3 Months Ended
	Aug. 31, 2020	Jun. 30, 2020	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Loss Contingencies [Line Items]
Operating lease right-of-use asset			$ 175,000		$ 274,000
Cash paid for amounts included in the measurement of operating lease liabilities			$ 100	$ 100
Immaterial Error Correction			Company recorded an immaterial non-cash error correction to eliminate the remaining prepaid retrospective insurance policy asset with a corresponding increase to research and development expense in the amount of $1.8 million
ResearchAndDevelopmentExpense			$ 1,800,000
Noncancelable operating lease agreement [Member] | Amended Operating Lease [Member]
Loss Contingencies [Line Items]
Description of lease term		August 2023
Option to extend the lease		option for an additional year
Percentage of increase in monthly base rent		4%
Operating lease right-of-use asset		$ 200,000
Additional noncancelable operating lease agreement [Member] | New Operating Lease [Member]
Loss Contingencies [Line Items]
Description of lease term	August 2020 through August 2023
Option to extend the lease	option for an additional year
Operating lease right-of-use asset	$ 200,000
Lease extended termination description	option to terminate the lease prior to its expiration with at least one month’s prior written notice and a one-time payment equal to four months’ rent.
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]
Percentage of increase in monthly base rent	4%
Cash paid for amounts included in the measurement of operating lease liabilities	$ 12,462,000
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]
Percentage of increase in monthly base rent	9%
Cash paid for amounts included in the measurement of operating lease liabilities	$ 14,524,000

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Future Minimum Payments for Operating Leases (Details) $ in Thousands	Mar. 31, 2024 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2024	$ 184
Total lease payments	184
Less: imputed interest	(5)
Total operating lease liabilities	$ 179

Commitments and Contingencies_3

Commitments and Contingencies - Schedule of Cash Flow Supplemental Disclosures (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Supplemental Cash Flow Information [Abstract]
Cash paid for amounts included in the measurement of operating lease liabilities	$ 100	$ 100