Kyverna Therapeutics (KYTX) 10-Q 14 May 24 2024 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2024	May 10, 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 File Number	001-41947
Entity Registrant Name	Kyverna Therapeutics, Inc.
Entity Central Index Key	0001994702
Current Fiscal Year End Date	--12-31
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	83-1365411
Entity Address, Address Line One	5980 Horton St.
Entity Address, Address Line Two	STE 550
Entity Address, City or Town	Emeryville
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94608
City Area Code	(510)
Local Phone Number	925-2492
Title of 12(b) Security	Common Stock, par value $0.00001 per share
Trading Symbol	KYTX
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding		43,115,244

Condensed Balance Sheets

Condensed Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Current assets
Cash and cash equivalents	$ 224,287	$ 34,647
Available-for-sale marketable securities	145,507	22,896
Prepaid expenses and other current assets	5,694	3,121
Total current assets	375,488	60,664
Restricted cash	570	565
Property and equipment, net	2,714	2,326
Operating lease right-of-use assets	8,486	6,494
Finance lease right-of-use assets	1,552	1,790
Other non-current assets	1,174	3,356
Total assets	389,984	75,195
Current liabilities
Accounts payable	7,451	4,358
Accrued compensation	1,363	2,812
Accrued license expense - related party	6,250	6,250
Other accrued expenses and current liabilities	3,083	3,519
Operating lease liabilities, short-term portion	2,739	1,964
Finance lease liabilities, short-term portion	979	956
Total current liabilities	21,865	19,859
Operating lease liabilities, net of short-term portion	6,461	5,238
Finance lease liabilities, net of short-term portion	667	921
Total liabilities	28,993	26,018
Commitments and contingencies (Note 7)
Stockholders' equity (deficit)
Preferred stock, 10,000,000 shares authorized, $0.00001 par value, no shares issued and outstanding as of March 31, 2024; no shares authorized, issued, and outstanding as of December 31, 2023
Common stock, $0.00001 par value; 490,000,000 and 140,492,016 shares authorized as of March 31, 2024 and December 31, 2023, respectively; 43,115,244 and 1,250,103 shares issued and outstanding as of March 31, 2024 and December 31, 2023, respectively
Additional paid-in capital	523,728	4,642
Accumulated other comprehensive income (loss)	(1)	4
Accumulated deficit	(162,736)	(136,043)
Total stockholders' equity (deficit)	360,991	(131,397)
Total liabilities, redeemable convertible preferred stock and stockholders' equity (deficit)	$ 389,984	75,195
Redeemable Convertible Preferred Stock
Current liabilities
Redeemable convertible preferred stock, no par value; no shares authorized, issued and outstanding as of March 31, 2024 $0.00001 par value, 14,556,997 shares authorized as of December 31, 2023; 114,556,997 shares issued and outstanding as of December 31, 2023; liquidation preference of $181,250 as of December 31, 2023		$ 180,574

Condensed Balance Sheets (Paren

Condensed Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Preferred stock shares authorized	10,000,000	0
Preferred stock par value	$ 0.00001
Preferred stock shares issued	0	0
Preferred stock shares outstanding	0	0
Common stock par value	$ 0.00001	$ 0.00001
Common stock shares authorized	490,000,000	140,492,016
Common stock shares issued	43,115,244	1,250,103
Common stock shares outstanding	43,115,244	1,250,103
Redeemable Convertible Preferred Stock
Temporary equity , par value	$ 0	$ 0.00001
Temporary equity shares authorized	0	114,556,997
Temporary equity shares issued	0	114,556,997
Temporary equity shares outstanding	0	114,556,997
Temporary equity liquidation preference		$ 181,250

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating expenses
Research and development	$ 22,476	$ 8,711
General and administrative	6,882	2,734
Total operating expenses	29,358	11,445
Loss from operations	(29,358)	(11,445)
Interest income	2,735	349
Interest expense	(44)	(44)
Other expense, net	(26)	(3)
Total other income, net	2,665	302
Net loss	(26,693)	(11,143)
Other comprehensive gain (loss)
Unrealized gain (loss) on available-for-sale marketable securities, net	(5)	18
Total other comprehensive gain (loss)	(5)	18
Net loss and other comprehensive loss	$ (26,698)	$ (11,125)
Net loss per share attributable to common stockholders, basic	$ (1.12)	$ (12.1)
Net loss per share attributable to common stockholders, diluted	$ (1.12)	$ (12.1)
Weighted-average shares of common stock outstanding, basic	23,754,062	921,260
Weighted-average shares of common stock outstanding, diluted	23,754,062	921,260

Condensed Statements of Redeema

Condensed Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Redeemable Convertible Preferred Stock
Beginning balance at Dec. 31, 2022	$ (73,997)		$ 1,706	$ (75,677)	$ (26)
Beginning balance, Shares at Dec. 31, 2022		1,007,537
Temporary equity, Beginning balance at Dec. 31, 2022						$ 120,674
Temporary equity, Beginning balance, Shares at Dec. 31, 2022						82,504,003
Common shares issued upon exercise of options	24		24
Common shares issued upon exercise of options,Shares		9,412
Stock-based compensation expense	468		468
Vesting of early exercised options and restricted stock	18		18
Net loss	(11,143)			(11,143)
Unrealized gain (loss) on available-for-sale marketable securities, net	18				18
Temporary equity, Ending balance at Mar. 31, 2023						$ 120,674
Temporary equity, Ending balance, Shares at Mar. 31, 2023						82,504,003
Ending balance at Mar. 31, 2023	(84,612)		2,216	(86,820)	(8)
Ending balance, Shares at Mar. 31, 2023		1,016,949
Beginning balance at Dec. 31, 2022	$ (73,997)		1,706	(75,677)	(26)
Beginning balance, Shares at Dec. 31, 2022		1,007,537
Temporary equity, Beginning balance at Dec. 31, 2022						$ 120,674
Temporary equity, Beginning balance, Shares at Dec. 31, 2022						82,504,003
Issuance of common stock upon initial public offering, net of underwriting commissions and issuance costs of $30,686 , Shares	349,321
Common shares issued upon exercise of options,Shares	349,321
Temporary equity, Ending balance at Dec. 31, 2023						$ 180,574
Temporary equity, Ending balance, Shares at Dec. 31, 2023						114,556,997
Ending balance at Dec. 31, 2023	$ (131,397)		4,642	(136,043)	4
Ending balance, Shares at Dec. 31, 2023		1,250,103
Temporary equity, Conversion of redeemable convertible preferred stock into common stock in connection with initial public offering						$ (180,574)
Temporary equity, Conversion of redeemable convertible preferred stock into common stock in connection with initial public offering ,Shares						(114,556,997)
Issuance of common stock upon initial public offering, net of underwriting commissions and issuance costs of $30,686	336,164		336,164
Issuance of common stock upon initial public offering, net of underwriting commissions and issuance costs of $30,686 , Shares		16,675,000
Conversion of redeemable convertible preferred stock into common stock in connection with initial public offering	180,574		180,574
Conversion of redeemable convertible preferred stock into common stock in connection with initial public offering ,Shares		25,171,265
Common shares issued upon exercise of options	$ 64		64
Common shares issued upon exercise of options,Shares	368,197	18,876
Stock-based compensation expense	$ 2,278		2,278
Vesting of early exercised options and restricted stock	6		6
Net loss	(26,693)			(26,693)
Unrealized gain (loss) on available-for-sale marketable securities, net	(5)				(5)
Temporary equity, Ending balance, Shares at Mar. 31, 2024						0
Ending balance at Mar. 31, 2024	$ 360,991		$ 523,728	$ (162,736)	$ (1)
Ending balance, Shares at Mar. 31, 2024		43,115,244

Condensed Statements of Redee_2

Condensed Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($)
Statement of Stockholders' Equity [Abstract]
Stock issuance costs	$ 30,686

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flows from operating activities:
Net loss	$ (26,693)	$ (11,143)
Adjustments to reconcile net loss to net cash used by operations:
Stock-based compensation	2,278	468
Accretion of discounts on available-for-sale marketable securities	(280)	(78)
Depreciation and amortization expense	482	394
Non-cash lease expense	526	384
Changes in assets and liabilities:
Prepaid expense and other current assets	(2,573)	(161)
Other non-current assets	(293)	(435)
Accounts payable	3,068	105
Accrued compensation	(1,449)	(777)
Other accrued expenses and current liabilities	(71)	126
Operating lease liability	(520)	(341)
Net cash used in operating activities	(25,525)	(11,458)
Cash flows from investing activities
Purchases of available-for-sale marketable securities	(145,336)
Proceeds from maturities of available-for-sale marketable securities	23,000	13,683
Purchases of property and equipment	(543)	(28)
Net cash provided by (used in) investing activities	(122,879)	13,655
Cash flows from financing activities
Proceeds from issuance of common stock upon initial public offering, net of underwriting commissions	341,171
Proceeds from exercise of common stock options	64	24
Principal paid on finance lease liabilities	(231)	(168)
Payments for offering costs	(2,955)
Net cash provided by (used in) financing activities	338,049	(144)
Net increase in cash and cash equivalents and restricted cash	189,645	2,053
Cash, cash equivalents and restricted cash, at beginning of period	35,212	38,289
Cash, cash equivalents and restricted cash, at end of period	224,857	40,342
Reconciliation of cash, cash equivalents and restricted cash to statement of financial position
Cash and cash equivalents	224,287	39,786
Restricted cash	570	556
Cash, cash equivalents and restricted cash at end of period	224,857	40,342
Supplemental disclosure for non-cash investing and financing activities
Conversion of 114,556,997 shares of redeemable convertible preferred stock to common stock upon the closing of initial public offering	180,574
Unpaid deferred offering costs included in accounts payable and other accrued expenses and current liabilities	406
Purchases of property and equipment in accounts payable	89
Vesting of restricted stock	6	18
Right-of-use asset obtained in exchange for operating and finance lease liability	2,518	357
Supplemental disclosure of cash flow information
Cash paid for interest	$ 44	$ 44

Condensed Statements of Cash _2

Condensed Statements of Cash Flows (Parenthetical)	3 Months Ended
	Mar. 31, 2024 shares
Statement of Cash Flows [Abstract]
Conversion of redeemable convertible preferred stock into common stock on completion of initial public offering	114,556,997

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (26,693)	$ (11,143)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Mar. 31, 2024
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

Description of Business, Organi

Description of Business, Organization and Liquidity	3 Months Ended
	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business, Organization and Liquidity	1. Description of Business, Organization and Liquidity Kyverna Therapeutics, Inc. (“Kyverna” or “the Company”) is a patient-centered, clinical-stage biopharmaceutical company focused on developing cell therapies for patients suffering from autoimmune diseases. The lead product candidate, KYV-101, is advancing through clinical development across two broad areas of autoimmune disease: rheumatology and neurology. The Company was incorporated on June 14, 2018 , was initially named BAIT Therapeutics, Inc., changed its name to Kyverna Therapeutics, Inc. on October 1, 2019, and is headquartered in Emeryville, California. Initial Public Offering On February 7, 2024, the Company’s Registration Statement on Form S-1 for its initial public offering (the “IPO”) was declared effective, and on February 12, 2024, the Company closed the IPO and issued 16,675,000 shares of common stock at a price to the public of $ 22.00 per share, including 2,175,000 shares issued upon the exercise of underwriters’ option to purchase additional shares of common stock. The Company received gross proceeds of $ 366.9 million. Net proceeds were $ 336.2 million, after deducting underwriting commissions and other offering costs totaling $ 30.7 million. On February 8, 2024, the Company’s common stock began trading on the Nasdaq Global Select Market under the symbol “KYTX”. Immediately prior to the IPO closing, all of the outstanding shares of the Company’s redeemable convertible preferred stock converted into shares of the Company’s common stock on a 1-for-4.5511 basis. Reverse Stock Split On January 30, 2024, the Company’s shareholders approved and the Company effected a reverse stock split of the shares of common stock at a ratio of 1-for-4.5511 (the “Reverse Stock Split”). The number of authorized shares and par value per share were not adjusted as a result of the Reverse Stock Split. All references to shares, restricted stock awards, restricted stock units and options to purchase common stock, share data, per share data, and related information contained in the financial statements have been retrospectively adjusted to reflect the effect of the Reverse Stock Split for all periods presented. The conversion ratios for each series of the Company’s redeemable convertible preferred stock, which was automatically converted into shares of common stock upon the closing of the IPO, were proportionally adjusted. Liquidity The Company has incurred losses and negative cash flows from operations since inception. As of March 31, 2024, the Company has an accumulated deficit of $ 162.7 million. The Company had net losses of $ 26.7 million and $ 11.1 million for the three months ended March 31, 2024 and 2023, respectively. The Company has historically financed its operations primarily through issuances of redeemable convertible preferred stock and convertible notes, revenue from its collaboration agreement and sale of shares of its common stock in the IPO. As of March 31, 2024, the Company had cash and cash equivalents and available-for-sale marketable securities of $ 369.8 million. The Company expects to continue to incur operating losses and negative cash flows from operations to support the development of its product candidates, to expand its product portfolio and to continue its research and development activities, including preclinical studies and clinical trials. The Company’s activities are subject to significant risks and uncertainties, including the completion of requisite clinical activities to support regulatory approvals, market acceptance of the Company’s product candidates, if approved, as well as the timing and extent of spending on research and development. There can be no assurance that the Company will ever earn revenue or achieve profitability, or if achieved, that the revenue or profitability will be sustained on a continuing basis. Unless and until it does, the Company will need to continue to raise additional capital. Based on its current operating plan, management estimates that its existing cash and cash equivalents and available-for-sale marketable securities balances will be sufficient to fund its operating plan and capital expenditure requirements for at least the next 12 months from the date of this Quarterly Report on Form 10-Q.

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 The accompanying condensed financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) and the requirements of the SEC for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP can be condensed or omitted. These condensed financial statements have been prepared on the same basis as the annual financial statements included in the Annual Report on Form 10-K for the fiscal year ended December 31, 2023, filed with the Securities and Exchange Commission (“SEC”) on March 26, 2024, except as noted below. In the opinion of our management, the information in these condensed financial statements reflects all adjustments, all of which are of a normal and recurring nature necessary for a fair statement of the financial position and results of operations for the reported interim periods. We consider events or transactions that occur after the balance sheet date but before the financial statements are issued to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure. The results of operations for interim periods are not necessarily indicative of results to be expected for the full year or any other interim period. Any reference in these notes to applicable guidance is meant to refer to the authoritative U.S. GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”). Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates and assumptions, including those related to research and development accrued expenses, valuation of its common stock prior to the IPO, stock-based compensation, valuation of deferred tax assets and uncertain income tax positions. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities and the amount reported as revenue and expenses that are not readily apparent from other sources. Actual results may differ materially from those estimates. Segment Information The Company operates and manages its business as one reportable and operating segment, which is the business of developing therapies for autoimmune and inflammatory diseases. The chief executive officer, who is the chief operating decision maker, reviews financial information on an aggregate basis for purposes of allocating resources and evaluating financial performance. All of the Company’s long-lived assets are located in the United States. Significant Accounting Policies There have been no material changes to the accounting policies discussed in Note 2 to the consolidated financial statements included in the Company’ s Annual Report on Form 10-K for the fiscal year ended December 31, 2023, filed with the SEC on March 26, 2024. Recent Accounting Pronouncements In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures . This ASU requires public entities, on an annual basis, to provide disclosure of specific categories in the rate reconciliation, as well as disclosure of income taxes paid disaggregated by jurisdiction. ASU 2023-09 is effective for fiscal years beginning after December 15, 2024, with early adoption permitted. The Company is currently evaluating the impact the adoption of this standard on its financial statements. In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures . This ASU requires public entities to disclose information about their reportable segments’ significant expenses and other segment items on an interim and annual basis. Public entities with a single reportable segment are required to apply the disclosure requirements in ASU 2023-07, as well as all existing segment disclosures and reconciliation requirements in ASC 280 on an interim and annual basis. ASU 2023-07 is effective for fiscal years beginning after December 15, 2023, and for interim periods within fiscal years beginning after December 15, 2024, with early adoption permitted. The Company is currently evaluating the impact of the adoption of this standard on its financial statements. In October 2023, the FASB issued ASU 2023-06, Disclosure Improvements: Codification Amendments in Response to the SEC’s Disclosure Update and Simplification Initiative . This ASU aligns the requirements in the ASC to the removal of certain disclosure requirements set out in Regulation S-X and Regulation S-K, announced by the SEC. The effective date for each amended topic in the ASC is either the date on which the SEC’s removal of the related disclosure requirement from Regulation S-X or Regulation S-K becomes effective, or on June 30, 2027, if the SEC has not removed the requirements by that date. Early adoption is prohibited. The Company is currently evaluating the impact of the adoption of this standard on its financial statements.

Fair Value Measurements and Fai

Fair Value Measurements and Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 2024
Fair Value Disclosures [Abstract]
Fair Value Measurements and Fair Value of Financial Instruments	3. Fair Value Measurements and Fair Value of Financial Instruments Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements, as follows: Level 1 —Quoted prices in active markets for identical assets or liabilities. Level 2 —Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 —Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability. The Company’s fair value hierarchy for its cash equivalents and available-for-sale marketable securities measured at fair value on a recurring basis as of March 31, 2024, was as follows (in thousands): Fair Value Measurements As of March 31, 2024 Total Level 1 Level 2 Level 3 Cash equivalents Money market funds $ 52,548 $ 52,548 $ — $ — U.S. Treasury bills 119,196 — 119,196 — Corporate debt obligations 25,047 — 25,047 — Federal agency obligations 10,001 — 10,001 — Available-for-sale marketable securities U.S. Treasury notes 29,748 — 29,748 — U.S. Treasury bills 115,759 — 115,759 — Total fair value of assets $ 352,299 $ 52,548 $ 299,751 $ — The Company’s fair value hierarchy for its cash equivalents and available-for-sale marketable securities measured at fair value on a recurring basis as of December 31, 2023, was as follows (in thousands): Fair Value Measurements As of December 31, 2023 Total Level 1 Level 2 Level 3 Cash equivalents Money market funds $ 29,050 $ 29,050 $ — $ — Available-for-sale marketable securities U.S. Treasury bills 22,896 — 22,896 — Total fair value of assets $ 51,946 $ 29,050 $ 22,896 $ — Financial assets measured at fair value on a recurring basis consist of the Company’s cash equivalents and available-for-sale marketable securities. Cash equivalents consisted of money market funds, and available-for-sale marketable securities consisted of U.S. Treasury notes and bills. The Company obtains pricing information from its investment manager and generally determines the fair value of available-for-sale marketable securities using standard observable inputs, including reported trades, broker/dealer quotes and bids and/or offers. The Company recognizes transfers into and out of levels within the fair value hierarchy in the period in which the actual event or change in circumstances that caused the transfer occurs.

Available-for-Sale Marketable S

Available-for-Sale Marketable Securities	3 Months Ended
	Mar. 31, 2024
Investments, Debt and Equity Securities [Abstract]
Available-for-Sale Marketable Securities	4. Available-for-Sale Marketable Securities As of March 31, 2024, the Company’s available-for-sale marketable securities consisted entirely of debt securities issued by the U.S. Treasury with contractual maturities on various dates through November 2024. The following table summarizes the amortized cost, unrealized gains and losses and fair value of the Company’s available-for-sale marketable securities as of March 31, 2024 (in thousands): Total Total Total Total Amortized Unrealized Unrealized Estimated As of March 31, 2024: Cost Gains Losses Fair Value U.S. Treasury notes $ 29,746 $ 2 $ — $ 29,748 U.S. Treasury bills 115,767 1 ( 9 ) 115,759 Total available-for-sale marketable securities $ 145,513 $ 3 $ ( 9 ) $ 145,507 The following table summarizes the amortized cost, unrealized gains and losses and fair value of the Company’s available-for-sale marketable securities as of December 31, 2023 (in thousands): Total Total Total Total Amortized Unrealized Unrealized Estimated As of December 31, 2023: Cost Gains Losses Fair Value U.S. Treasury bills $ 22,892 $ 4 $ — $ 22,896 Total available-for-sale marketable securities $ 22,892 $ 4 $ — $ 22,896 As of March 31, 2024 and December 31, 2023, no significant facts or circumstances were present to indicate a deterioration in the creditworthiness of the issuers of the Company’s marketable securities, and the Company has no requirement or intention to sell these securities before maturity or recovery of their amortized cost basis. The Company considered the current and expected future economic and market conditions and determined that its investments were not significantly impacted by such conditions. For all securities with a fair value less than its amortized cost basis, the Company determined the decline in fair value below amortized cost basis to be immaterial and non-credit related, and therefore no allowance for losses has been recorded. During the three months ended March 31, 2024 and 2023, the Company did no t recognize any impairment losses on its investments. As of each of March 31, 2024 and December 31, 2023, accrued interest receivable was $ 0.4 million and zero , respectively , and included in the fair value of available-for-sale marketable securities and cash equivalents. The Company’s accounting policy is to not measure an allowance for credit losses for accrued interest receivables and to write-off any uncollectible accrued interest receivable as a reversal of interest income in a timely manner, which it considers to be in the period in which the Company determines the accrued interest will not be collected. During the three months ended March 31, 2024 and 2023, the Company did no t write off any accrued interest receivables.

Property and Equipment, Net

Property and Equipment, Net	3 Months Ended
	Mar. 31, 2024
Property, Plant and Equipment [Abstract]
Property and Equipment, Net	5. Property and Equipment, Net Property and equipment, net, consists of the following (in thousands): March 31, December 31, 2024 2023 Laboratory equipment $ 3,708 $ 3,409 Computer equipment and software 138 138 Furniture and fixtures 916 622 Leasehold improvements 684 645 Property and equipment, gross 5,446 4,814 Less accumulated depreciation ( 2,732 ) ( 2,488 ) $ 2,714 $ 2,326 Depreciation and amortization expense related to property and equipment was $ 0.3 million and $ 0.2 million for the three months ended March 31, 2024 and 2023, respectively.

Significant Agreements

Significant Agreements	3 Months Ended
	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Significant Agreements	6. Significant Agreements Patent License Agreements with the National Institutes of Health In May 2021, the Company entered into two patent license agreements (the “NIH Agreements”) with the National Institutes of Health (the “NIH”), pursuant to which the Company obtained exclusive, worldwide licenses to certain patents to use an anti-CD19 CAR in the Company’s autologous and allogeneic CAR T-cell products for the treatment of patients with autoimmune disease. The Company paid $ 3.3 million for acquired licenses. Under the NIH Agreements, commencing in January 2023 and subsequently on January 1 of each calendar year thereafter, the Company is also required to make minimum annual royalty payments of $ 0.2 million, which shall be credited against any earned royalties due based on a low single-digit percentage of net sales made in a respective year. In addition, benchmark royalties following the completion of certain regulatory-and clinical-related benchmarks are due to the NIH, with the minimum cumulative royalty due for a product reaching FDA approval or foreign-equivalent approval totaling $ 5.7 million for the autologous patent license agreement and $ 1.7 million for the allogeneic patent license agreement. Additional benchmark royalties would be payable for a subsequent indication under each NIH Agreement. If the Company enters into a sublicensing agreement, it will be required to pay the NIH a sublicense royalty payment as a percentage of the fair market value of any consideration received for each sublicense granted. The sublicensing percentage starts at a high teens to low twenties percentage if clinical trials for the product have not yet begun and decreases to a mid-single-digit percentage if the product has received FDA approval or foreign-equivalent approval. Unless terminated sooner, the NIH Agreements remain in effect until the last licensed patent right granted pursuant to the respective agreement expires. The acquisition of the licenses, including patent rights and know-how, was accounted for as an asset acquisition. As the acquired technology did not have an alternative use for accounting purposes, the consideration of $ 3.3 million was recorded as research and development expense in the statements of operations and comprehensive loss for the year ended December 31, 2021. No benchmark royalties were probable or payable as of March 31, 2024 and December 31, 2023. Intellia License and Collaboration Agreement In December 2021, the Company entered into a License and Collaboration Agreement (the “Intellia Agreement”) with Intellia Therapeutics, Inc. (“Intellia”) to research and develop an allogeneic CD19-directed CAR cell therapy product (the “CRISPR Product”), suitable for validation through pre-clinical and clinical proof-of-concept clinical trials, including the performance of activities as agreed in the collaboration plan. Pursuant to the Intellia Agreement, Intellia granted to the Company an exclusive, worldwide, sublicensable in multiple tiers, royalty bearing license under certain of Intellia’s intellectual property to research, develop, sell and otherwise exploit the CRISPR Product. The Company is performing the majority of the work under the collaboration plan. As consideration for the licenses granted to the Company pursuant to the Intellia Agreement, the Company issued to Intellia shares of its Series B Preferred Stock with the fair value of $ 7.0 million. The Company is also obligated to make aggregate milestone payments to Intellia of up to $ 64.5 million upon the achievement of specified development and regulatory milestones and is obligated to pay to Intellia low to mid-single-digit royalties as a percentage of annual worldwide sales, subject to certain adjustments, and additional potential royalties and milestones to Intellia’s licensors. The royalties are payable on a country-by-country basis, commencing upon the first commercial sale of the CRISPR Product in the applicable country and expiring upon the later of (i) 12 years after the first commercial sale or (ii) the expiration of the last-to-expire valid patent claim. Under the Intellia Agreement, Intellia owns rights, title and interests in and to any intellectual property developed in the course of performance under the Intellia Agreement that is not specifically directed to the CRISPR Product. The Company granted to Intellia certain non-exclusive, royalty-free, fully paid-up, worldwide licenses under the Company’s intellectual property solely to perform the activities designated to Intellia under the collaboration, and to research, develop or otherwise exploit any human therapeutic product that is developed or commercialized by Intellia, utilizes or incorporates Intellia intellectual property and that is not the CRISPR Product or any product directed to CD19 or any other B-cell antigen. In addition, the Company granted Intellia an exclusive option (the “Intellia Option”) to enter into a co-development and co-commercialization agreement with the Company for the CRISPR Product, (the “Co-Co Agreement”) for a fee payable to the Company. If Intellia exercises the Intellia Option, the Company and Intellia would share equally the regulatory and clinical development expenses associated with obtaining approval of the CRISPR Product in the U.S. and would also share equally all net profits and losses from commercialization of the CRISPR Product in the U.S. If Intellia exercises the Intellia Option, no milestone payments will be due and payable from that time forward and the Company will only pay royalties on sales outside of the U.S. In addition, upon exercise of the Intellia Option, following regulatory approval of the CRISPR Product, Intellia will have exclusive commercialization rights for the CRISPR Product for U.S. administration, subject to the Company’s rights to co-promote the CRISPR Product in the U.S., and the Company will retain the sole and exclusive rights to research, develop, or otherwise exploit the CRISPR Product for rest-of-world administration and shall have sole decision-making authority in relation thereto, subject to the parties’ obligations to cooperate regarding certain development, regulatory and commercialization strategies. During the term of the Co-Co Agreement, subject to certain exceptions, neither party will clinically develop or commercialize a cell therapy product directed to CD19 other than the CRISPR Product for use in the treatment or prevention of certain indications set forth in the Intellia Agreement and any additional indication that the parties mutually agree to include (any such product, a Competitive Product); provided, however, that (i) any products for use in any indications that are the subject of a development program or third-party collaboration as of the effective date of the Co-Co Agreement shall not be considered Competitive Products and (ii) any products for use in any additional indications that are the subject of a development program or third-party collaboration as of the date that such additional indications are included in the global development plan shall not be considered Competitive Products. The Intellia Agreement terminates on a country-by-country basis upon the expiration of the last valid claim within Intellia’s patent rights covering the CRISPR Product within such country, unless the agreement is earlier terminated in its entirety by either party for insolvency, by either party for material breach of contract, by Intellia if the Company participates in legal action or proceeding challenging the validity or enforceability of Intellia’s patents, or by the execution of the Co-Co Agreement. The Company may terminate the Intellia Agreement in its entirety, or on a country-by-country basis, by providing a written notice after the expiration or termination of the Intellia Option. Following the expiration of the term for a given country, the licenses granted to the Company in such country will automatically become fully paid-up, perpetual, irrevocable and royalty-free licenses. No milestone payments were probable or payable as of March 31, 2024 and December 31, 2023. Gilead Collaboration, Option and License Agreement (Related Party) In January 2020, the Company entered into the Collaboration, Option and License Agreement (the “Gilead Agreement”) with Gilead Sciences, Inc. (“Gilead”). Simultaneously with the entry into the Gilead Agreement, the Company entered into (i) a License Agreement (the “Kite Agreement”) with Kite Pharma, Inc. (“Kite”), an affiliate of Gilead (see below), and (ii) a stock purchase agreement, pursuant to which the Company issued to Gilead an aggregate of 6,890,744 shares of its Series A-2 redeemable convertible preferred stock, of which 4,042,066 shares were issued as consideration under the Kite Agreement (see below). Pursuant to the Gilead Agreement, the Company and Gilead collaborated to develop potential cell-based therapy products, which could use the SynNotch Technology and the SynNotch intellectual property related thereto, controlled by Gilead through Kite, for the treatment, diagnosis or prevention of autoimmune, inflammatory, or allogeneic stem cell transplant inflammatory diseases (excluding post-transplant infectious diseases), subject to certain exceptions. The Gilead Agreement initially involved the research and development of cell-based products for the treatment, diagnosis or prevention of two indications under two research programs and non-exclusive research licenses, specifically, Crohn’s disease, or Program A, and Ulcerative colitis, or Program B. Upon execution of the Gilead Agreement, Gilead paid the Company a one-time, non-refundable and non-creditable payment of $ 17.5 million. Pursuant to the Gilead Agreement, the Company also granted Gilead, on a research program-by-program basis, an exclusive option, exercisable at any time during the Option Period for such program, to obtain an exclusive license under such program’s intellectual property to develop, manufacture, and commercialize optioned products belonging to such program for a specified fee and on the terms and conditions set out in the Gilead Agreement. For purposes of the foregoing, an Option Period meant, on a program-by-program basis, the period commencing on the date of execution of the Gilead Agreement and ending upon the earlier of (i) the expiration of the review period for such program, and (ii) the ten-year anniversary of the date of execution of the Gilead Agreement. Unless terminated earlier, the Gilead Agreement was to expire, with respect to each program, (i) upon such program becoming a terminated program, or (ii) on an optioned product-by-optioned product and country-by-country basis, upon the expiration of the royalty term with respect to such optioned product in such country with respect to such program. Gilead had the right to terminate the Gilead Agreement at will, in its sole discretion, in its entirety or on a program-by-program or optioned program-by-optioned program basis at any time upon ninety days’ prior written notice to the Company. In addition, either party was able to terminate the Gilead Agreement for uncured material breach by the other party, or upon the occurrence of insolvency-related events of the other party. The royalty term under the Gilead Agreement continued on an optioned product-by-optioned product and country-by-country basis until the latest of: (i) the date on which there is no valid claim of a program patent; (ii) the expiration of any regulatory exclusivity with respect to such optioned product in the relevant country; and (iii) the ten-year anniversary of the date of the first commercial sale of such optioned product in such country. The Company concluded that the Gilead Agreement was in the scope of ASC Topic 606. The Company estimated the transaction price as $ 17.5 million, which was allocated to two performance obligations, Program A and Program B, based on the relative fair value of each program. Other milestone payments were constrained and not included in the transaction price as they were considered not probable. On November 30, 2022, after the completion of research activities under Program A and Program B, Gilead provided the Company with notice that Program A and Program B were terminated. As of December 31, 2022, there were no other active programs under the Gilead Agreement and deferred revenue was zero. On October 24, 2023, after agreement by both parties that the Gilead Agreement had no active programs, Gilead provided the Company with 90 days’ written notice to terminate the Gilead Agreement, and such termination became effective as of January 22, 2024. Kite License Agreement (Related Party) Concurrently with the Gilead Agreement, the Company entered into the Kite Agreement. Pursuant to the Kite Agreement, Kite granted to the Company a ten-year, co-exclusive license for the SynNotch technology primarily used in the Company’s own internal research and development programs for the treatment, diagnosis or prevention of autoimmune, inflammatory or allogeneic stem cell transplant inflammatory diseases (excluding post-transplant infectious diseases). Upon expiration of the ten-year co-exclusive license term, the license will become a non-exclusive license through expiration of the related patents. Kite had licensed certain of the SynNotch technology included in the Kite Agreement pursuant to that certain Amended and Restated Exclusive License Agreement, between The Regents of the University of California and Kite (as successor to Cell Design Labs, Inc.), or the UCSF License Agreement. The Company is responsible for all costs and payments arising under the UCSF License Agreement and as a result of activities under the Kite Agreement, including earned royalties based on a low single-digit percentage of net sales, milestone payments in an aggregate amount of up to $ 10.8 million and accrued interest payables. Pursuant to the Kite Agreement, the Company is also obligated to pay mid-teen-and mid-single-digit percentages of annual maintenance fees, minimum annual royalties and patent prosecution costs payable under the UCSF License Agreement during the co-exclusive term and non-exclusive term, respectively. The Company was also obligated to pay a $ 6.3 million sublicensing fee under the UCSF License Agreement, which the Company agreed to offset with future milestone payments payable by Gilead under the Gilead Agreement. Unless terminated earlier, the Kite Agreement will expire upon the expiration of all licensed patents and Kite improvement patents therein. The Company has the right to terminate the Kite Agreement at will, in the Company’s sole discretion, in its entirety upon 90 days’ written notice to Kite. In addition, either party may terminate the Kite Agreement for uncured material breach by the other party, or upon the occurrence of insolvency-related events of the other party. The acquisition of the co-exclusive license under the Kite Agreement, including patent rights and know-how, was accounted for as an asset acquisition. As the acquired technology did not have an alternative use for accounting purposes, the license consideration of $ 3.5 million and the sublicensing fee of $ 6.3 million was recorded as a research and development expense in the statements of operations and comprehensive loss for the year ended December 31, 2020. As of March 31, 2024 and December 31, 2023, the Company recognized the total sublicensing fee of $ 6.3 million as current accrued license expense—related party, of which $ 2.5 million became payable as a result of the qualified financing. The Company expects to pay such amount of $ 2.5 million by mid-2024. The remaining $ 3.8 million was available to be offset against future milestones payable by Gilead under the Gilead Agreement; however, due to the termination of the Gilead Agreement, there are no future milestones payable to offset the sublicensing fee, and the payment schedule for the remaining $ 3.8 million of the sublicensing fee has not been agreed to by the Company and Gilead. The annual maintenance fee, patent prosecution costs and minimal annual royalties are expensed as incurred and were minimal for each of the three months ended March 31, 2024 and 2023.

Equity Incentive Plan

Equity Incentive Plan	3 Months Ended
	Mar. 31, 2024
Share-Based Payment Arrangement [Abstract]
Equity Incentive Plan	10. Equity Incentive Plan In January 2024, the Company’s board of directors adopted, and stockholders approved, the Company’ s 2024 Equity Incentive Plan (the “2024 Plan”), which became effective on February 6, 2024. The Company initially reserved 4,215,000 shares of common stock for future issuance under the 2024 Plan. In addition, 3,960,713 shares issued and outstanding under the Company’s 2019 Equity Incentive Plan, as amended (the “2019 Plan”), may be added to the 2024 Plan as such shares become available from time to time if awards terminate, expire, or lapse for any reason without the delivery of shares, or are reacquired or withheld (or not issued) to satisfy a tax withholding obligation or the purchase or exercise price. The 2024 Plan also provides that the number of shares reserved and available for issuance will automatically increase each January 1, beginning on January 1, 2025 and ending on January 1, 2034, by an amount equal to the lesser of (i) 5 % of the shares of common stock outstanding on the last day of the immediately preceding fiscal year, and (ii) such smaller number of shares of stock as determined by the Company’s board of directors. No more than 12,645,000 shares of stock may be issued upon the exercise of incentive stock options under the 2024 Plan. The Company may grant incentive stock options (“ISOs” ), nonstatutory stock options (“NSOs”), restricted stock units (“RSUs”), restricted stock awards (“RSAs”), stock appreciation rights (“SARs”), performance awards and other awards to the Company’s officers, employees, directors and consultants. Options under the 2024 Plan may be granted for periods of up to 10 years at exercise prices no less than the fair market value of the common stock on the date of grant and usually vest over four years . The exercise price of an option granted to a 10% stockholder may not be less than 110 % of the fair market value of the shares on the date of grant and such option may not be exercisable after the expiration of five years from the date of grant. The grant date fair market value of all awards made under our 2024 Plan and all cash compensation paid by us to any non-employee director for services as a director in any fiscal year may not exceed $ 750,000 , increased to $ 1,000,000 in the fiscal year of their initial service as a non-employee director. The 2024 Plan is the successor to the 2019 Plan and no additional awards may be granted under the 2019 Plan. All outstanding awards granted under the 2019 Plan will remain subject to the terms of the 2019 Plan. The 2019 Plan provided for the grant of incentive stock options, nonstatutory stock options, RSUs and RSAs to the Company’s officers, employees, directors and consultants. As of March 31, 2024, only ISOs and NSOs had been granted under the 2019 Plan. As of March 31, 2024, 3,928,132 shares of the Company’s common stock were reserved for issuance under the 2024 Plan. In January 2024, the Company’s board of directors and stockholders adopted the Company’ s 2024 Employee Stock Purchase Plan (the “ESPP”), which became effective on February 6, 2024. The Company initially reserved 422,000 shares of common stock for future issuance under the ESPP. The ESPP permits participants to purchase common stock through payroll deductions of up to 15 % of their eligible compensation. Employees purchase shares of common stock at a price per share equal to 85 % of the lower of the fair market value at the start of the offering or on the date of purchase. The aggregate number of shares reserved for issuance under the ESPP will automatically increase each January 1, beginning on January 1, 2025 and ending on January 1, 2034, by an amount equal to the lesser of 1 % of the Company's total outstanding shares of common stock on the immediately preceding December 31st, and 422,000 shares or a lesser number of shares as may be determined by the Company ’s board of directors. A summary of option activity under the 2019 Plan and 2024 Plan is as follows: Number of Weighted- Weighted- Aggregate Outstanding at December 31, 2023 * 4,310,034 $ 4.09 9.09 $ 11,810 Options granted 286,868 $ 22.51 Options exercised * ( 368,197 ) $ 3.15 Outstanding at March 31, 2024 4,228,705 $ 5.42 8.94 $ 82,104 Exercisable at March 31, 2024 ** 1,717,997 $ 3.48 8.21 $ 36,705 Vested and expected to vest at March 31, 2024 4,228,705 $ 5.42 8.94 $ 82,104 * Outstanding number of options as of December 31, 2023 excludes 349,321 shares of common stock issued in connection with the early exercised options for a non-recourse promissory note, which were not considered substantive for accounting purposes . These shares are included in the number of options exercised during the three months ended March 31, 2024, upon the note forgiveness in January 2024 (see Note 9). ** Includes 1,119,349 shares of unvested stock options for which the holders have the right to early exercise such options as of March 31, 2024. Aggregate intrinsic value represents the difference between the fair value of the underlying common stock and the exercise price. The weighted-average grant date fair value of options granted for the three months ended March 31, 2024 and 2023, was $ 17.52 and $ 2.46 , respectively. The intrinsic value of options exercised during the three months ended March 31, 2024 and 2023 was $ 3.1 million and less than $ 0.1 million, respectively, and is calculated as the difference between the exercise price and the fair value of common stock as of the exercise date. Early Exercise of Employee Options Certain employees received stock options that allow for exercise of the stock option prior to vesting. The shares of common stock issued upon an early exercise that have not yet vested are subject to repurchase by the Company in the event of termination of the holder’s continuous status as a service provider, at the price paid by the holder. Proceeds from the early exercise of stock options are recorded as repurchase liability, and as shares vest, they are recognized as additional paid-in capital in the balance sheets. Shares purchased by employees pursuant to the early exercise of stock options are not deemed, for accounting purposes, to be issued until those shares vest according to their respective vesting schedules, and the Company recognizes stock-based compensation expense related to these options as they continue to vest. As of March 31, 2024 and December 31, 2023 , there was zero and $ 0.1 million repurchase liability related to the unvested shares, respectively. As of March 31, 2024 and December 31, 2023, zero and 8,125 common stock shares, respectively, remained subject to the right of repurchase as a result of the early exercise of stock options and are included in common stock outstanding. Early exercises as of December 31, 2023 exclude 349,321 shares of common stock issued in connection with the early exercised options for a non-recourse promissory note, which are not considered substantive for accounting purposes. Stock-Based Compensation Expense The Black-Scholes option pricing model, used to estimate fair value of stock-based awards, requires the use of the following assumptions: • Fair value of common stock . Prior to the IPO, the fair market value of common stock was determined by the Board of Directors with assistance from management and external valuation experts. The approach to estimating the fair market value of common stock was consistent with the methods outlined in the American Institute of Certified Public Accountants’ Accounting and Valuation Guide, Valuation of Privately-Held-Company Equity Securities Issued as Compensation (the “Practice Aid”). Subsequent to the IPO, the fair value of common stock is the Company’s closing price per share on the Nasdaq Global Select Market at the grant date. • Expected Term . The expected term of options granted represents the period of time that the options are expected to be outstanding. Due to the lack of historical exercise history, the expected term of the Company’s employee stock options has been determined by calculating the midpoint of the contractual term of the options and the weighted-average vesting period. Grants to nonemployees are based on the contractual term. • Expected Volatility . The expected stock price volatility assumption was determined by examining the historical volatilities for industry peers, as the Company did not have any trading history for the common stock. The Company will continue to analyze the historical stock price volatility and expected term assumption as more historical data for the common stock becomes available. • Risk-Free Interest Rate . The risk-free interest rate assumption is based on the U.S. Treasury instrument whose term was consistent with the expected term of the Company’s stock options. • Dividends . The Company has not paid any cash dividends on common stock since inception and does not anticipate paying any dividends in the foreseeable future. Consequently, an expected dividend yield of zero was used. The fair value of options granted to employees and nonemployees was estimated at the grant date using the following assumptions for the three months ended March 31, 2024 and 2023, respectively: Three Months Ended March 31, 2024 2023 Employees Expected volatility 93 % 95 % Expected dividend yield 0 % 0 % Expected term (in years) 6.07 - 6.08 6.0 - 6.1 Risk-free interest rate 4.1 % - 4.2 % 3.6 % - 3.7 % The following table presents the classification of stock-based compensation expense related to stock options granted to employees and nonemployees (in thousands): Three Months Ended March 31, 2024 2023 Research and development $ 581 $ 123 General and administrative 1,697 345 Total stock-based compensation expense $ 2,278 $ 468 In connection with the CEO note forgiveness (see Note 9), the Company recognized stock-based compensation expense of $ 1.1 million in general and administrative expenses in the statement of operations and comprehensive loss for the three months ended March 31, 2024. As of March 31, 2024, total unrecognized stock-based compensation expense was $ 16.0 million, which is expected to be recognized over a weighted-average period of 3.1 years.

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Stockholders	3 Months Ended
	Mar. 31, 2024
Earnings Per Share [Abstract]
Net Loss Per Share Attributable to Common Stockholders	11. Net Loss Per Share Attributable to Common Stockholders The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders (in thousands, except share and per share data): Three Months Ended March 31, 2024 2023 Numerator: Net loss attributable to common stockholders $ ( 26,693 ) $ ( 11,143 ) Denominator: Weighted average shares used in computing basic and diluted net loss per share 23,754,062 921,260 Net loss per share attributable to common stockholders, basic and diluted: $ ( 1.12 ) $ ( 12.10 ) The potential shares of common stock that were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented because including them would have had an antidilutive effect were as follows: As of March Ended 31, 2024 2023 Redeemable convertible preferred stock, as converted — 18,128,357 Options issued and outstanding 4,228,705 2,427,954 Unvested early exercised common stock options — 81,253 Unvested early exercised common stock options exercised for non-recourse promissory note (Note 9) — 349,321 4,228,705 20,986,885

Commitments and Contingent Liab

Commitments and Contingent Liabilities	3 Months Ended
	Mar. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingent Liabilities	7. Commitments and Contingent Liabilities License Agreements The Company entered into license agreements with the NIH, Intellia and Kite (see Note 6), pursuant to which the Company is required to pay certain milestone payments contingent upon the achievement of specific development and regulatory events. No such milestones were achieved or probable as of March 31, 2024 and December 31, 2023. The Company is required to pay royalties on sales of products developed under these agreements. The Company’s product candidates were in clinical trials or the pre-clinical stage of development as of March 31, 2024 and December 31, 2023, and no such royalties were due. Legal Contingencies From time to time, the Company may become involved in legal proceedings arising from the ordinary course of business. The Company records a liability for such matters when it is probable that future losses will be incurred and that such losses can be reasonably estimated. Significant judgment is required to determine both probability and the estimated amount. Management is not aware of any legal matters that could have a material adverse effect on the Company’s financial position, results of operations or cash flows. Guarantees and Indemnifications In the normal course of business, the Company enters into agreements that contain a variety of representations and provide for general indemnification. The Company’s exposure under these agreements is unknown because it involves claims that may be made against the Company in the future. To date, the Company has not paid any claims or been required to defend any action related to its indemnification obligations. As of March 31, 2024 and December 31, 2023, the Company does not have any material indemnification claims that were probable or reasonably possible. Leases As of March 31, 2024, the Company leased 68,153 square feet of office and laboratory space in Emeryville, California under operating leases which have terms through February 2027 . The Company has multiple leases for laboratory equipment with terms of 36 months that are accounted for as finance leases. Some of the Company’s office and lab space were leased under short-term lease agreements during the three months ended March 31, 2023. Components of the lease expense for the three months ended March 31, 2024 and 2023, were as follows (in thousands): Three Months Ended March 31, 2024 2023 Operating lease cost $ 689 $ 609 Finance lease cost: Amortization of right-of-use assets 237 185 Interest on lease liabilities 44 44 Short-term lease cost — 1 Variable lease cost 291 237 Total lease expense $ 1,261 $ 1,076 Supplemental cash flow information related to leases was as follows for the three months ended March 31, 2024 and 2023 (in thousands): Three Months Ended March 31, 2024 2023 Cash paid for amounts included in the measurement Operating cash flows from operating leases $ 624 $ 565 Operating cash flows from finance leases 44 44 Financing cash flows from finance leases 231 168 Right-of-use assets obtained in exchange for lease Operating leases 2,518 — Finance leases — 357 The following is a schedule by year of future payments of the Company’s lease liabilities as of March 31, 2024 (in thousands): Operating Leases Finance Leases 2024 (remainder of the year) $ 2,484 $ 823 2025 3,563 828 2026 4,046 147 2027 446 — Total lease payments 10,539 1,798 Less interest ( 1,339 ) ( 152 ) Total lease liability balance 9,200 1,646 Less: current portion ( 2,739 ) ( 979 ) Non-current lease liabilities $ 6,461 $ 667 The weighted-average remaining lease term and discount rate related to the Company’s operating lease liabilities as of March 31, 2024, were 2.9 years and 9 %, respectively. The weighted-average remaining lease term and discount rate related to the Company’s finance lease liabilities as of March 31, 2024, were 1.8 years and 11 %, respectively. The weighted-average remaining lease term and discount rate related to the Company’s operating lease liabilities as of December 31, 2023, were 3.1 years and 8 %, respectively. The weighted-average remaining lease term and discount rate related to the Company’s finance lease liabilities as of December 31, 2023, were 2.0 years and 11 %, respectively. The discount rates were based on the Company’s estimate of its incremental borrowing rate, as the discount rates implicit in the leases could not be readily determined. As the Company does not have any outstanding debt, the Company estimated the incremental borrowing rate based on its estimated credit rating and available market information.

Redeemable Convertible Preferre

Redeemable Convertible Preferred Stock	3 Months Ended
	Mar. 31, 2024
Equity [Abstract]
Redeemable Convertible Preferred Stock	8. Redeemable Convertible Preferred Stock In June 2023 and July 2023, the Company issued 32,052,994 additional shares of Series B redeemable convertible preferred stock to existing and new investors for an aggregate cash consideration of $ 60.0 million at a price per share of $ 1.871 9, net of $ 0.1 million issuance costs. On February 12, 2024, in connection with the closing of the IPO, all outstanding shares of redeemable convertible preferred stock automatically converted into 25,171,265 shares of common stock. Subsequent to the closing of the IPO, there were no shares of redeemable convertible preferred stock outstanding.

Common Stock

Common Stock	3 Months Ended
	Mar. 31, 2024
Equity [Abstract]
Common Stock	9. Common Stock As of March 31, 2024 and December 31, 2023, common stock reserved for future issuance was as follows: March 31, December 31, 2024 2023 Redeemable convertible preferred stock, as converted — 25,171,265 Outstanding stock option awards ( 349,321 shares issued in connection with the early exercised options for a non-recourse promissory note are excluded from shares reserved for issuance as of December 31, 2023 and none as of March 31, 2024) 4,228,705 3,960,713 ESPP shares available for future grants 422,000 — Shares available for future option grants 3,928,132 487,650 Total shares reserved for future issuance 8,578,837 29,619,628 Early Exercise of Options for a Promissory Note In December 2022, the Company’s chief executive officer (the “CEO”), a related party, early exercised options for 349,321 shares of common stock in exchange for a partial recourse promissory note receivable with the principal amount of $ 1.1 million. The note bore interest at 4.27 % per annum and was to be due in December 2027 . For accounting purposes, the promissory note was determined to be non-recourse and, as such, the issuance of the promissory note and subsequent early exercise of stock options were considered not substantive. While the issued shares were not considered outstanding for accounting purposes, they were legally issued and had voting and dividend rights. The shares were included in common stock on the statement of redeemable convertible preferred stock and stockholders’ deficit as of December 31, 2023, and were not included in the calculation of net loss per share attributable to common stockholders for the three months ended March 31, 2023. On January 12, 2024, the Company and the CEO entered into a note forgiveness letter, pursuant to which the promissory note and all accrued interest thereon in an aggregate amount of $ 1.1 million were forgiven. As the shares subject to the options that were early exercised were vested as of the date of the forgiveness of the note, these are included in the calculation of net loss per share attributable to common stockholders from the date of the note’s forgiveness. The Company concluded that the note forgiveness was effectively a repricing of options and is a modification. Therefore, the incremental stock-based compensation expense was recognized for the vested shares at the modification date (see Note 10).

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2024
Related Party Transactions [Abstract]
Related Party Transactions	12. Related Party Transactions For the three months ended March 31, 2024, the Company recorded less than $ 0.1 million to deferred offering costs related to an advisory services agreement with one of its board members. On January 12, 2024, the Company and the CEO entered into a note forgiveness letter, pursuant to which the promissory note and all accrued interest thereon in an aggregate amount of $ 1.1 million were forgiven. The promissory note was issued by the CEO in December 2022 in connection with early exercised options (see Note 9).

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2024
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) and the requirements of the SEC for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP can be condensed or omitted. These condensed financial statements have been prepared on the same basis as the annual financial statements included in the Annual Report on Form 10-K for the fiscal year ended December 31, 2023, filed with the Securities and Exchange Commission (“SEC”) on March 26, 2024, except as noted below. In the opinion of our management, the information in these condensed financial statements reflects all adjustments, all of which are of a normal and recurring nature necessary for a fair statement of the financial position and results of operations for the reported interim periods. We consider events or transactions that occur after the balance sheet date but before the financial statements are issued to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure. The results of operations for interim periods are not necessarily indicative of results to be expected for the full year or any other interim period. Any reference in these notes to applicable guidance is meant to refer to the authoritative U.S. GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”).
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates and assumptions, including those related to research and development accrued expenses, valuation of its common stock prior to the IPO, stock-based compensation, valuation of deferred tax assets and uncertain income tax positions. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities and the amount reported as revenue and expenses that are not readily apparent from other sources. Actual results may differ materially from those estimates.
Segment Information	Segment Information The Company operates and manages its business as one reportable and operating segment, which is the business of developing therapies for autoimmune and inflammatory diseases. The chief executive officer, who is the chief operating decision maker, reviews financial information on an aggregate basis for purposes of allocating resources and evaluating financial performance. All of the Company’s long-lived assets are located in the United States.
Significant Accounting Policies	Significant Accounting Policies There have been no material changes to the accounting policies discussed in Note 2 to the consolidated financial statements included in the Company’ s Annual Report on Form 10-K for the fiscal year ended December 31, 2023, filed with the SEC on March 26, 2024.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures . This ASU requires public entities, on an annual basis, to provide disclosure of specific categories in the rate reconciliation, as well as disclosure of income taxes paid disaggregated by jurisdiction. ASU 2023-09 is effective for fiscal years beginning after December 15, 2024, with early adoption permitted. The Company is currently evaluating the impact the adoption of this standard on its financial statements. In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures . This ASU requires public entities to disclose information about their reportable segments’ significant expenses and other segment items on an interim and annual basis. Public entities with a single reportable segment are required to apply the disclosure requirements in ASU 2023-07, as well as all existing segment disclosures and reconciliation requirements in ASC 280 on an interim and annual basis. ASU 2023-07 is effective for fiscal years beginning after December 15, 2023, and for interim periods within fiscal years beginning after December 15, 2024, with early adoption permitted. The Company is currently evaluating the impact of the adoption of this standard on its financial statements. In October 2023, the FASB issued ASU 2023-06, Disclosure Improvements: Codification Amendments in Response to the SEC’s Disclosure Update and Simplification Initiative . This ASU aligns the requirements in the ASC to the removal of certain disclosure requirements set out in Regulation S-X and Regulation S-K, announced by the SEC. The effective date for each amended topic in the ASC is either the date on which the SEC’s removal of the related disclosure requirement from Regulation S-X or Regulation S-K becomes effective, or on June 30, 2027, if the SEC has not removed the requirements by that date. Early adoption is prohibited. The Company is currently evaluating the impact of the adoption of this standard on its financial statements.

Fair Value Measurements and F_2

Fair Value Measurements and Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2024
Fair Value Disclosures [Abstract]
Schedule of Assets Measured at Fair Value on a Recurring Basis	The Company’s fair value hierarchy for its cash equivalents and available-for-sale marketable securities measured at fair value on a recurring basis as of March 31, 2024, was as follows (in thousands): Fair Value Measurements As of March 31, 2024 Total Level 1 Level 2 Level 3 Cash equivalents Money market funds $ 52,548 $ 52,548 $ — $ — U.S. Treasury bills 119,196 — 119,196 — Corporate debt obligations 25,047 — 25,047 — Federal agency obligations 10,001 — 10,001 — Available-for-sale marketable securities U.S. Treasury notes 29,748 — 29,748 — U.S. Treasury bills 115,759 — 115,759 — Total fair value of assets $ 352,299 $ 52,548 $ 299,751 $ — The Company’s fair value hierarchy for its cash equivalents and available-for-sale marketable securities measured at fair value on a recurring basis as of December 31, 2023, was as follows (in thousands): Fair Value Measurements As of December 31, 2023 Total Level 1 Level 2 Level 3 Cash equivalents Money market funds $ 29,050 $ 29,050 $ — $ — Available-for-sale marketable securities U.S. Treasury bills 22,896 — 22,896 — Total fair value of assets $ 51,946 $ 29,050 $ 22,896 $ —

Available-for-Sale Marketable_2

Available-for-Sale Marketable Securities (Tables)	3 Months Ended
	Mar. 31, 2024
Investments, Debt and Equity Securities [Abstract]
Schedule of Available-for-Sale Marketable Securities	The following table summarizes the amortized cost, unrealized gains and losses and fair value of the Company’s available-for-sale marketable securities as of March 31, 2024 (in thousands): Total Total Total Total Amortized Unrealized Unrealized Estimated As of March 31, 2024: Cost Gains Losses Fair Value U.S. Treasury notes $ 29,746 $ 2 $ — $ 29,748 U.S. Treasury bills 115,767 1 ( 9 ) 115,759 Total available-for-sale marketable securities $ 145,513 $ 3 $ ( 9 ) $ 145,507 The following table summarizes the amortized cost, unrealized gains and losses and fair value of the Company’s available-for-sale marketable securities as of December 31, 2023 (in thousands): Total Total Total Total Amortized Unrealized Unrealized Estimated As of December 31, 2023: Cost Gains Losses Fair Value U.S. Treasury bills $ 22,892 $ 4 $ — $ 22,896 Total available-for-sale marketable securities $ 22,892 $ 4 $ — $ 22,896

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	3 Months Ended
	Mar. 31, 2024
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net, consists of the following (in thousands): March 31, December 31, 2024 2023 Laboratory equipment $ 3,708 $ 3,409 Computer equipment and software 138 138 Furniture and fixtures 916 622 Leasehold improvements 684 645 Property and equipment, gross 5,446 4,814 Less accumulated depreciation ( 2,732 ) ( 2,488 ) $ 2,714 $ 2,326

Commitments and Contingent Li_2

Commitments and Contingent Liabilities (Tables)	3 Months Ended
	Mar. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Components of Lease Expense	Components of the lease expense for the three months ended March 31, 2024 and 2023, were as follows (in thousands): Three Months Ended March 31, 2024 2023 Operating lease cost $ 689 $ 609 Finance lease cost: Amortization of right-of-use assets 237 185 Interest on lease liabilities 44 44 Short-term lease cost — 1 Variable lease cost 291 237 Total lease expense $ 1,261 $ 1,076
Schedule of Supplemental Cash Flow Information Related to Lease	Supplemental cash flow information related to leases was as follows for the three months ended March 31, 2024 and 2023 (in thousands): Three Months Ended March 31, 2024 2023 Cash paid for amounts included in the measurement Operating cash flows from operating leases $ 624 $ 565 Operating cash flows from finance leases 44 44 Financing cash flows from finance leases 231 168 Right-of-use assets obtained in exchange for lease Operating leases 2,518 — Finance leases — 357
Schedule by Year of Future Payments of Lease Liabilities	The following is a schedule by year of future payments of the Company’s lease liabilities as of March 31, 2024 (in thousands): Operating Leases Finance Leases 2024 (remainder of the year) $ 2,484 $ 823 2025 3,563 828 2026 4,046 147 2027 446 — Total lease payments 10,539 1,798 Less interest ( 1,339 ) ( 152 ) Total lease liability balance 9,200 1,646 Less: current portion ( 2,739 ) ( 979 ) Non-current lease liabilities $ 6,461 $ 667

Common Stock (Tables)

Common Stock (Tables)	3 Months Ended
	Mar. 31, 2024
Equity [Abstract]
Schedule of Common Stock Reserved for Future Issuance	As of March 31, 2024 and December 31, 2023, common stock reserved for future issuance was as follows: March 31, December 31, 2024 2023 Redeemable convertible preferred stock, as converted — 25,171,265 Outstanding stock option awards ( 349,321 shares issued in connection with the early exercised options for a non-recourse promissory note are excluded from shares reserved for issuance as of December 31, 2023 and none as of March 31, 2024) 4,228,705 3,960,713 ESPP shares available for future grants 422,000 — Shares available for future option grants 3,928,132 487,650 Total shares reserved for future issuance 8,578,837 29,619,628

Equity Incentive Plan (Tables)

Equity Incentive Plan (Tables)	3 Months Ended
	Mar. 31, 2024
Share-Based Payment Arrangement [Abstract]
Summary of Option Activity	A summary of option activity under the 2019 Plan and 2024 Plan is as follows: Number of Weighted- Weighted- Aggregate Outstanding at December 31, 2023 * 4,310,034 $ 4.09 9.09 $ 11,810 Options granted 286,868 $ 22.51 Options exercised * ( 368,197 ) $ 3.15 Outstanding at March 31, 2024 4,228,705 $ 5.42 8.94 $ 82,104 Exercisable at March 31, 2024 ** 1,717,997 $ 3.48 8.21 $ 36,705 Vested and expected to vest at March 31, 2024 4,228,705 $ 5.42 8.94 $ 82,104
Schedule of Fair Value of Options Granted to Employees and Nonemployees Estimated at the Grant Date using the Assumptions	The fair value of options granted to employees and nonemployees was estimated at the grant date using the following assumptions for the three months ended March 31, 2024 and 2023, respectively: Three Months Ended March 31, 2024 2023 Employees Expected volatility 93 % 95 % Expected dividend yield 0 % 0 % Expected term (in years) 6.07 - 6.08 6.0 - 6.1 Risk-free interest rate 4.1 % - 4.2 % 3.6 % - 3.7 %
Schedule of Stock-based Compensation Expense	The following table presents the classification of stock-based compensation expense related to stock options granted to employees and nonemployees (in thousands): Three Months Ended March 31, 2024 2023 Research and development $ 581 $ 123 General and administrative 1,697 345 Total stock-based compensation expense $ 2,278 $ 468

Net Loss Per Share Attributab_2

Net Loss Per Share Attributable to Common Stockholders (Tables)	3 Months Ended
	Mar. 31, 2024
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders	The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders (in thousands, except share and per share data): Three Months Ended March 31, 2024 2023 Numerator: Net loss attributable to common stockholders $ ( 26,693 ) $ ( 11,143 ) Denominator: Weighted average shares used in computing basic and diluted net loss per share 23,754,062 921,260 Net loss per share attributable to common stockholders, basic and diluted: $ ( 1.12 ) $ ( 12.10 )
Schedule of Potential Shares of Common Stock that were Excluded from the Computation of Diluted Net Loss Per Share	The potential shares of common stock that were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented because including them would have had an antidilutive effect were as follows: As of March Ended 31, 2024 2023 Redeemable convertible preferred stock, as converted — 18,128,357 Options issued and outstanding 4,228,705 2,427,954 Unvested early exercised common stock options — 81,253 Unvested early exercised common stock options exercised for non-recourse promissory note (Note 9) — 349,321 4,228,705 20,986,885

Description of Business, Orga_2

Description of Business, Organization and Liquidity - Additional Information (Details) $ / shares in Units, $ in Thousands				3 Months Ended		12 Months Ended
	Feb. 12, 2024 USD ($) $ / shares shares	Feb. 08, 2024	Jan. 30, 2024	Mar. 31, 2024 USD ($) shares	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($) shares
Subsidiary, Sale of Stock [Line Items]
Incorporated date				Jun. 14, 2018
Shares issued | shares						349,321
Net proceeds				$ 341,171
Description of reverse stock split				On January 30, 2024, the Company’s shareholders approved and the Company effected a reverse stock split of the shares of common stock at a ratio of 1-for-4.5511 (the “Reverse Stock Split”). The number of authorized shares and par value per share were not adjusted as a result of the Reverse Stock Split. All references to shares, restricted stock awards, restricted stock units and options to purchase common stock, share data, per share data, and related information contained in the financial statements have been retrospectively adjusted to reflect the effect of the Reverse Stock Split for all periods presented. The conversion ratios for each series of the Company’s redeemable convertible preferred stock, which was automatically converted into shares of common stock upon the closing of the IPO, were proportionally adjusted.
Reverse stock split conversion ratio		0.219	0.219
Accumulated deficit				$ 162,736		$ 136,043
Net loss				26,693	$ 11,143
Cash and cash equivalents and available-for-sale marketable securities				$ 369,800
Common Stock
Subsidiary, Sale of Stock [Line Items]
Shares issued | shares				16,675,000
Initial Public Offering | Common Stock
Subsidiary, Sale of Stock [Line Items]
Shares issued | shares	16,675,000
Share price | $ / shares	$ 22
Gross proceeds	$ 366,900
Net proceeds	336,200
Underwriting discounts and commissions and other offering costs	$ 30,700
Underwriters option to purchase | Common Stock
Subsidiary, Sale of Stock [Line Items]
Shares issued | shares	2,175,000

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended
	Mar. 31, 2024 Segment
Accounting Policies [Abstract]
Number of reportable segments	1
Number of operating segments	1

Fair Value Measurements and F_3

Fair Value Measurements and Fair Value of Financial Instruments - Schedule of Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale marketable securities	$ 145,507	$ 22,896
U.S. Treasury Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale marketable securities	29,748
U.S. Treasury Bills
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale marketable securities	115,759	22,896
Fair Value, Recurring Basis
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total fair value of assets	352,299	51,946
Fair Value, Recurring Basis | U.S. Treasury Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale marketable securities	29,748
Fair Value, Recurring Basis | U.S. Treasury Bills
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale marketable securities	115,759	22,896
Fair Value, Recurring Basis | Corporate Debt Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	25,047
Fair Value, Recurring Basis | Money Market Funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	52,548	29,050
Fair Value, Recurring Basis | U.S. Treasury Bills
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	119,196
Fair Value, Recurring Basis | Federal Agency Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	10,001
Fair Value, Recurring Basis | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total fair value of assets	52,548	29,050
Fair Value, Recurring Basis | Level 1 | Money Market Funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	52,548	29,050
Fair Value, Recurring Basis | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total fair value of assets	299,751	22,896
Fair Value, Recurring Basis | Level 2 | U.S. Treasury Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale marketable securities	29,748
Fair Value, Recurring Basis | Level 2 | U.S. Treasury Bills
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale marketable securities	115,759	$ 22,896
Fair Value, Recurring Basis | Level 2 | Corporate Debt Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	25,047
Fair Value, Recurring Basis | Level 2 | U.S. Treasury Bills
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	119,196
Fair Value, Recurring Basis | Level 2 | Federal Agency Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	$ 10,001

Available-for-Sale Marketable_3

Available-for-Sale Marketable Securities - Schedule of Available-for-Sale Marketable Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-Sale [Line Items]
Total Amortized Cost	$ 145,513	$ 22,892
Total Unrealized Gains	3	4
Total Unrealized Losses	(9)
Total Estimated Fair Value	145,507	22,896
U.S. Treasury Notes
Debt Securities, Available-for-Sale [Line Items]
Total Amortized Cost	29,746
Total Unrealized Gains	2
Total Estimated Fair Value	29,748
U.S. Treasury Bills
Debt Securities, Available-for-Sale [Line Items]
Total Amortized Cost	115,767	22,892
Total Unrealized Gains	1	4
Total Unrealized Losses	(9)
Total Estimated Fair Value	$ 115,759	$ 22,896

Available-for-Sale Marketable_4

Available-for-Sale Marketable Securities - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Impairment losses on investments	$ 0	$ 0
Accrued interest receivable	400,000		$ 0
Accrued write off interest receivables	$ 0	$ 0

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 5,446	$ 4,814
Less accumulated depreciation	(2,732)	(2,488)
Property and equipment, net	2,714	2,326
Laboratory Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	3,708	3,409
Computer Equipment and Software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	138	138
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	916	622
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 684	$ 645

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$ 0.3	$ 0.2

Significant Agreements - Additi

Significant Agreements - Additional Information (Details)		1 Months Ended			3 Months Ended	12 Months Ended
	Oct. 24, 2023	Dec. 31, 2021 USD ($)	May 31, 2021 USD ($) Agreements	Jan. 31, 2020 USD ($) shares	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($)	Dec. 31, 2020 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Shares issued | shares						349,321
Gilead Sciences, Inc.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration, option and license agreement, description					Pursuant to the Gilead Agreement, the Company also granted Gilead, on a research program-by-program basis, an exclusive option, exercisable at any time during the Option Period for such program, to obtain an exclusive license under such program’s intellectual property to develop, manufacture, and commercialize optioned products belonging to such program for a specified fee and on the terms and conditions set out in the Gilead Agreement. For purposes of the foregoing, an Option Period meant, on a program-by-program basis, the period commencing on the date of execution of the Gilead Agreement and ending upon the earlier of (i) the expiration of the review period for such program, and (ii) the ten-year anniversary of the date of execution of the Gilead Agreement.Unless terminated earlier, the Gilead Agreement was to expire, with respect to each program, (i) upon such program becoming a terminated program, or (ii) on an optioned product-by-optioned product and country-by-country basis, upon the expiration of the royalty term with respect to such optioned product in such country with respect to such program. Gilead had the right to terminate the Gilead Agreement at will, in its sole discretion, in its entirety or on a program-by-program or optioned program-by-optioned program basis at any time upon ninety days’ prior written notice to the Company. In addition, either party was able to terminate the Gilead Agreement for uncured material breach by the other party, or upon the occurrence of insolvency-related events of the other party.The royalty term under the Gilead Agreement continued on an optioned product-by-optioned product and country-by-country basis until the latest of: (i) the date on which there is no valid claim of a program patent; (ii) the expiration of any regulatory exclusivity with respect to such optioned product in the relevant country; and (iii) the ten-year anniversary of the date of the first commercial sale of such optioned product in such country.
Patent License Agreements | National Institutes of Health
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Minimum annual royalty payments			$ 200,000
Number of agreements | Agreements			2
Acquired licenses, amount paid			$ 3,300,000
Royalties payable					$ 0	$ 0
Patent License Agreements | Research and Development Expense | National Institutes of Health
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Acquired licenses, amount paid							$ 3,300,000
Patent License Agreements | Autologous Patent License Agreement | National Institutes of Health
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Cumulative royalty due			5,700,000
Patent License Agreements | Allogeneic Patent License Agreement | National Institutes of Health
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Cumulative royalty due			$ 1,700,000
License and Collaboration Agreement | Intellia Therapeutics, Inc.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Temporary equity shares issued, fair value		$ 7,000,000
Milestone payments					0	0
License and Collaboration Agreement | Intellia Therapeutics, Inc. | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payments		$ 64,500,000
Collaboration, Option and License Agreement | Gilead Sciences, Inc.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Proceeds from one-time non-refundable and non-creditable payment				$ 17,500,000
Estimated transaction price				17,500,000
Number of days of notice period for terminating agreement	90 days
Kite License Agreement | Kite Pharma, Inc.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sublicensing fee				6,300,000
License consideration								$ 3,500,000
Sublicense fee to be offset against future milestone payable, not agreed					3,800,000
Sublicense fee payable related to qualified financing						2,500,000
Kite License Agreement | Kite Pharma, Inc. | Accrued License Expense, Related Party
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sublicensing fee					$ 6,300,000	$ 6,300,000
Kite License Agreement | Kite Pharma, Inc. | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payments				$ 10,800,000
Kite License Agreement | Kite Pharma, Inc. | Series A-2 Redeemable Convertible Preferred Stock
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Shares issued | shares				4,042,066
Kite License Agreement | Research and Development Expense | Kite Pharma, Inc.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sublicensing fee								$ 6,300,000
Stock Purchase Agreement | Gilead Sciences, Inc. | Series A-2 Redeemable Convertible Preferred Stock
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Shares issued | shares				6,890,744

Commitments and Contingent Li_3

Commitments and Contingent Liabilities - Additional Information (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2024 USD ($) ft²	Dec. 31, 2023 USD ($)	Mar. 31, 2023
Lessee, Lease, Description [Line Items]
Milestone payments achieved or probable	$ 0	$ 0
Royalties due	$ 0	$ 0
Operating lease, description	As of March 31, 2024, the Company leased 68,153 square feet of office and laboratory space in Emeryville, California under operating leases which have terms through February 2027.
Operating lease weighted average lease term	2 years 10 months 24 days	3 years 1 month 6 days
Operating lease weighted average discount rate	9%	8%
Finance lease weighted average lease term	1 year 9 months 18 days	2 years
Finance lease weighted average discount rate	11%	11%
Office and Laboratory
Lessee, Lease, Description [Line Items]
Lessee operating lease square feet leased | ft²	68,153
Operating lease term month and year	2027-02
Laboratory Equipment
Lessee, Lease, Description [Line Items]
Finance lease term of contract			36 months

Commitments and Contingent Li_4

Commitments and Contingent Liabilities - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Operating lease cost	$ 689	$ 609
Finance lease cost:
Amortization of right-of-use assets	237	185
Interest on lease liabilities	44	44
Short-term lease cost		1
Variable lease cost	291	237
Total lease expense	$ 1,261	$ 1,076

Commitments and Contingent Li_5

Commitments and Contingent Liabilities - Schedule of Supplemental Cash Flow Information Related to Leases (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 624	$ 565
Operating cash flows from finance leases	44	44
Financing cash flows from finance leases	231	168
Right-of-use assets obtained in exchange for lease obligations upon inception of lease (noncash):
Operating leases	$ 2,518
Finance leases		$ 357

Commitments and Contingent Li_6

Commitments and Contingent Liabilities - Schedule by Year of Future Payments of Lease Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Operating Leases
2024 (remainder of the year)	$ 2,484
2025	3,563
2026	4,046
2027	446
Total lease payments	10,539
Less interest	(1,339)
Total lease liability balance	9,200
Less: current portion	(2,739)	$ (1,964)
Non-current lease liabilities	6,461	5,238
Finance Leases
2024 (remainder of the year)	823
2025	828
2026	147
Total lease payments	1,798
Less interest	(152)
Total lease liability balance	1,646
Less: current portion	(979)	(956)
Non-current lease liabilities	$ 667	$ 921

Common Stock - Schedule of Comm

Common Stock - Schedule of Common Stock Reserved for Future Issuance (Details) - shares	Mar. 31, 2024	Dec. 31, 2023
Class of Stock [Line Items]
Shares reserved for future issuance	8,578,837	29,619,628
Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Shares reserved for future issuance		25,171,265
Outstanding Stock Option Awards
Class of Stock [Line Items]
Shares reserved for future issuance	4,228,705	3,960,713
ESPP Shares Available for Future Grants
Class of Stock [Line Items]
Shares reserved for future issuance	422,000
Shares Available for Future Option Grants
Class of Stock [Line Items]
Shares reserved for future issuance	3,928,132	487,650

Common Stock - Schedule of Co_2

Common Stock - Schedule of Common Stock Reserved for Future Issuance (Parenthetical) (Details) - shares	1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2022	Mar. 31, 2024	Dec. 31, 2023
Class of Stock [Line Items]
Options exercised	349,321	368,197	349,321
Employee Stock Option
Class of Stock [Line Items]
Options exercised		0	349,321

Common Stock - Additional Infor

Common Stock - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2022	Mar. 31, 2024	Dec. 31, 2023	Jan. 12, 2024
Class of Stock [Line Items]
Options exercised	349,321	368,197	349,321
Promissory note principal amount	$ 1.1
Promissory note, interest rate	4.27%
Promissory note maturity	2027-12
Accrued interest				$ 1.1
Related Party
Class of Stock [Line Items]
Accrued interest				$ 1.1

Redeemable Convertible Prefer_2

Redeemable Convertible Preferred Stock - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		2 Months Ended	3 Months Ended
	Feb. 12, 2024	Jul. 31, 2023	Mar. 31, 2024
Class of Stock [Line Items]
Temporary equity shares issued	0
Stock issuance costs			$ 2,955
Shares of common stock converted	25,171,265
Series B Preferred Stock [Member]
Class of Stock [Line Items]
Temporary equity shares issued		32,052,994
Aggregate cash consideration		$ 60,000
Price per share		$ 1.871
Stock issuance costs		$ 100

Equity Incentive Plan - Additio

Equity Incentive Plan - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended		12 Months Ended
	Jan. 31, 2024	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares available for grant		8,578,837		29,619,628
Weighted-average grant date fair value of options granted		$ 17.52	$ 2.46
Intrinsic value of options exercised		$ 3,100,000
Repurchase liability related to the unvested shares		$ 0		$ 100,000
Common stock shares repurchased under early exercise of Stock option		0		8,125
Issuance of common stock upon initial public offering, net of underwriting commissions and issuance costs of $30,686 , Shares				349,321
Recognized stock-based compensation expense		$ 2,278	$ 468
Unrecognized stock-based compensation expense		$ 16,000,000
Weighted average period over which unrecognized compensation is expected to be recognized (in years)		3 years 1 month 6 days
Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Intrinsic value of options exercised			$ 100,000
CEO
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Recognized stock-based compensation expense		$ 1,100,000
ESPP [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares available for grant	422,000
Employees purchase shares of common stock at a price per share, percentage of the lower of the fair market value	85%
Percentage of common stock outstanding	1%
ESPP [Member] | Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Eligible compensation percentage through payroll deductions, maximum	15%
2024 Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares available for grant	4,215,000	3,928,132
Shares of common stock outstanding on the last day of the immediately preceding fiscal year, percentage	5%
Share-based compensation arrangement by share-based payment award, shares issuable	12,645,000
Vesting period	4 years
2024 Plan [Member] | Minimum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Fair market value of the shares on the date of grant, percentage	110%
2024 Plan [Member] | Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Options under the Plan may be granted for periods, maximum	10 years
Grant date fair market value of all awards and all cash compensation, paid	$ 750,000
2024 Plan [Member] | Initial Service as a Non-employee Director | Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Grant date fair market value of all awards and all cash compensation, paid	$ 1,000,000
2019 Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Shares issued	3,960,713
Shares outstanding	3,960,713

Equity Incentive Plan - Summary

Equity Incentive Plan - Summary of Option Activity (Details) - USD ($)	1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2022	Mar. 31, 2024	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Number of Options, Outstanding at beginning of period		4,310,034
Options granted		286,868
Options exercised	(349,321)	(368,197)	(349,321)
Number of Options, Outstanding at ending of period		4,228,705	4,310,034
Number of Options, Exercisable		1,717,997
Number Of Options, Vested and expected to vest		4,228,705
Weighted Average Exercise Price Per Share, Beginning Balance		$ 4.09
Granted (in USD per share)		22.51
Exercised (in USD per share)		3.15
Weighted Average Exercise Price Per Share, Ending Balance		5.42	$ 4.09
Weighted Average Exercise Price Per Share, Exercisable (in USD per share)		3.48
Weighted Average Exercise Price Per Share, vested and expected to vest		$ 5.42
Weighted Average Remaining Contractual Term, Outstanding		8 years 11 months 8 days	9 years 1 month 2 days
Weighted Average Remaining Contractual Term, Exercisable		8 years 2 months 15 days
Weighted Average Remaining Contractual Term, Vested and expected to vest		8 years 11 months 8 days
Aggregate Intrinsic Value, Outstanding		$ 82,104	$ 11,810
Aggregate Intrinsic Value, Exercisable		36,705
Aggregate Intrinsic Value, Vested and expected to vest		$ 82,104

Equity Incentive Plan - Summa_2

Equity Incentive Plan - Summary of Option Activity (Parenthetical) (Details) - shares	1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2022	Mar. 31, 2024	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Options exercised	349,321	368,197	349,321
Unvested stock options		1,119,349

Equity Incentive Plan - Schedul

Equity Incentive Plan - Schedule of Fair Value of Options Granted to Employees and Nonemployees Estimated at the Grant Date using the Assumptions (Details) - Employee Stock Option	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected volatility	93%	95%
Expected dividend yield	0%	0%
Risk-free interest rate, minimum	4.10%	3.60%
Risk-free interest rate, maximum	4.20%	3.70%
Minimum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected term (in years)	6 years 25 days	6 years
Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected term (in years)	6 years 29 days	6 years 1 month 6 days

Equity Incentive Plan - Sched_2

Equity Incentive Plan - Schedule of Stock-based Compensation Expense (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock based compensation expense	$ 2,278	$ 468
Research and Development
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock based compensation expense	581	123
General and Administrative
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock based compensation expense	$ 1,697	$ 345

Net Loss Per Share Attributab_3

Net Loss Per Share Attributable to Common Stockholder - Schedule of Computation of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Numerator:
Net Income (Loss)	$ (26,693)	$ (11,143)
Denominator
Weighted average shares used in computing basic	23,754,062	921,260
Weighted-average shares of common stock outstanding, diluted	23,754,062	921,260
Net loss per share attributable to common stockholders, basic	$ (1.12)	$ (12.1)
Net loss per share attributable to common stockholders, diluted	$ (1.12)	$ (12.1)

Net Loss Per Share Attributab_4

Net Loss Per Share Attributable to Common Stockholders - Schedule of Potential Shares of Common Stock that were Excluded from the Computation of Diluted Net Loss Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential shares of common stock that were excluded from the computation of diluted net loss per share	4,228,705	20,986,885
Redeemable Convertible Preferred Stock, as Converted
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential shares of common stock that were excluded from the computation of diluted net loss per share		18,128,357
Employee Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential shares of common stock that were excluded from the computation of diluted net loss per share	4,228,705	2,427,954
Unvested Early Exercised Common Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential shares of common stock that were excluded from the computation of diluted net loss per share		81,253
Unvested early exercised common stock options exercised for non-recourse promissory note
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential shares of common stock that were excluded from the computation of diluted net loss per share		349,321

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($)	Mar. 31, 2024	Jan. 12, 2024
Related Party Transaction [Line Items]
Accrued interest		$ 1,100,000
Related Party
Related Party Transaction [Line Items]
Accrued interest		$ 1,100,000
Maximum
Related Party Transaction [Line Items]
Deferred offering costs	$ 100,000