RayzeBio (RYZB) 10-Q 13 Nov 23 2023 Q3 Quarterly report Financial data

Cover

Cover - shares	9 Months Ended
	Sep. 30, 2023	Nov. 07, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
Document Transition Report	false
Entity File Number	001-41799
Entity Registrant Name	RayzeBio, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	84-4388509
Entity Address, Address Line One	5505 Morehouse Drive,
Entity Address, Address Line Two	Suite 300
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92121
City Area Code	(619)
Local Phone Number	937-2757
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	RYZB
Security Exchange Name	NASDAQ
Entity Current Reporting Status	No
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		59,919,502
Entity Central Index Key	0001825367
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2023

Condensed Balance Sheets

Condensed Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 251,964	$ 129,159
Short-term investments	288,205	167,087
Prepaid expenses and other current assets	4,817	3,791
Total current assets	544,986	300,037
Property and equipment, net	49,696	15,084
Restricted cash	339	339
Right-of-use assets	8,484	9,308
Other assets	8	8
Total assets	603,513	324,776
Current liabilities:
Accounts payable	2,237	2,623
Accrued liabilities	13,610	6,691
Current portion of operating lease liabilities	1,266	1,144
Total current liabilities	17,113	10,458
Unvested stock liability	2,620	929
Operating lease liabilities, net of current portion	8,458	9,425
Commitments and contingencies (Note 3)
Convertible preferred stock, $0.0001 par value; authorized shares – no shares and 179,639,650 at September 30, 2023 and December 31, 2022, respectively; issued and outstanding shares – no shares and 34,942,503 at September 30, 2023 and December 31, 2022, respectively; liquidation preference $0 and $397,755 at September 30, 2023 and December 31, 2022, respectively	0	415,258
Stockholders’ equity (deficit):
Preferred stock, $0.0001 par value, 10,000,000 shares authorized – no shares issued and outstanding	0	0
Common stock, $0.0001 par value; authorized shares – 700,000,000 and 246,500,000 at September 30, 2023 and December 31, 2022, respectively; issued shares – 61,047,189 and 5,515,050 at September 30, 2023 and December 31, 2022, respectively; outstanding shares – 59,826,184 and 4,532,751 at September 30, 2023 and December 31, 2022, respectively	6	1
Additional paid-in capital	755,829	19,374
Accumulated other comprehensive loss	(386)	(553)
Accumulated deficit	(180,127)	(130,116)
Total stockholders’ equity (deficit)	575,322	(111,294)
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	$ 603,513	$ 324,776
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0

Condensed Balance Sheets (Paren

Condensed Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Convertible preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Convertible preferred stock, shares authorized (in shares)	0	179,639,650
Convertible preferred stock, shares issued (in shares)	0	34,942,503
Convertible preferred stock, shares outstanding (in shares)	0	34,942,503
Convertible preferred stock, liquidation preference	$ 0	$ 397,755
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	700,000,000	246,500,000
Common stock, shares issued (in shares)	61,047,189	5,515,050
Common stock, shares outstanding (in shares)	59,826,184	4,532,751

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Operating Expenses:
Research and development	$ 18,170	$ 18,828	$ 48,759	$ 46,416
General and administrative	3,481	2,122	9,479	8,244
Total operating expenses	21,651	20,950	58,238	54,660
Loss from operations	(21,651)	(20,950)	(58,238)	(54,660)
Other Income (Expense):
Interest income	3,490	503	9,485	762
Other expense	(30)	0	(49)	0
Total other income (expense)	3,460	503	9,436	762
Net loss	(18,191)	(20,447)	(48,802)	(53,898)
Dividends	(1,209)	(4,550)	(1,209)	(4,550)
Net loss attributable to common stockholders	(19,400)	(24,997)	(50,011)	(58,448)
Other Comprehensive Income (Loss):
Unrealized gain (loss) on investment securities	180	102	167	(696)
Comprehensive Loss	$ (19,220)	$ (24,895)	$ (49,844)	$ (59,144)
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (1.26)	$ (6.55)	$ (5.99)	$ (17.14)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (1.26)	$ (6.55)	$ (5.99)	$ (17.14)
Weighted-average shares of common stock outstanding, basic (in shares)	15,399,901	3,817,307	8,350,628	3,409,940
Weighted-average shares of common stock outstanding, diluted (in shares)	15,399,901	3,817,307	8,350,628	3,409,940

Condensed Statements of Convert

Condensed Statements of Convertible Preferred Stock and Stockholders’ Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2021	22,498,827
Beginning balance at Dec. 31, 2021	$ 255,909
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of Series D convertible preferred stock, net of issuance costs (in shares)	12,443,676
Issuance of Series D convertible preferred stock, net of issuance costs	$ 159,349
Ending balance (in shares) at Sep. 30, 2022	34,942,503
Ending balance at Sep. 30, 2022	$ 415,258
Beginning balance (shares) at Dec. 31, 2021		3,138,956
Beginning balance at Dec. 31, 2021	(54,574)	$ 0	$ 771	$ (239)	$ (55,106)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Deemed dividend upon down round of common stock	0		4,550		(4,550)
Issuance of common stock (in shares)		851,943
Issuance of common stock	6,548	$ 1	6,547
Repurchase of common shares (in shares)		(194,514)
Repurchase of common shares	(1,860)				(1,860)
Exercise of vested stock options (in shares)		44,115
Exercise of vested stock options	85		85
Vesting of early exercised stock options and founder shares (in shares)		555,174
Vesting of early exercised stock options and founder shares	620		620
Stock-based compensation	4,219		4,219
Other noncash compensation	269		269
Unrealized gain (loss) on investment securities	(696)			(696)
Net loss	(53,898)				(53,898)
Ending balance (shares) at Sep. 30, 2022		4,395,674
Ending balance at Sep. 30, 2022	$ (99,287)	$ 1	17,061	(935)	(115,414)
Beginning balance (in shares) at Dec. 31, 2021	22,498,827
Beginning balance at Dec. 31, 2021	$ 255,909
Ending balance (in shares) at Dec. 31, 2022	34,942,503
Ending balance at Dec. 31, 2022	$ 415,258
Beginning balance (shares) at Dec. 31, 2021		3,138,956
Beginning balance at Dec. 31, 2021	(54,574)	$ 0	771	(239)	(55,106)
Ending balance (shares) at Dec. 31, 2022		4,532,751
Ending balance at Dec. 31, 2022	$ (111,294)	$ 1	19,374	(553)	(130,116)
Beginning balance (in shares) at Jun. 30, 2022	22,498,827
Beginning balance at Jun. 30, 2022	$ 255,909
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of Series D convertible preferred stock, net of issuance costs (in shares)	12,443,676
Issuance of Series D convertible preferred stock, net of issuance costs	$ 159,349
Ending balance (in shares) at Sep. 30, 2022	34,942,503
Ending balance at Sep. 30, 2022	$ 415,258
Beginning balance (shares) at Jun. 30, 2022		3,401,685
Beginning balance at Jun. 30, 2022	(87,154)	$ 0	4,300	(1,037)	(90,417)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Deemed dividend upon down round of common stock	0		4,550		(4,550)
Issuance of common stock (in shares)		851,943
Issuance of common stock	6,548	$ 1	6,547
Exercise of vested stock options (in shares)		5,153
Exercise of vested stock options	10		10
Vesting of early exercised stock options and founder shares (in shares)		136,893
Vesting of early exercised stock options and founder shares	119		119
Stock-based compensation	1,447		1,447
Other noncash compensation	88		88
Unrealized gain (loss) on investment securities	102			102
Net loss	(20,447)				(20,447)
Ending balance (shares) at Sep. 30, 2022		4,395,674
Ending balance at Sep. 30, 2022	$ (99,287)	$ 1	17,061	(935)	(115,414)
Beginning balance (in shares) at Dec. 31, 2022	34,942,503
Beginning balance at Dec. 31, 2022	$ 415,258
Increase (Decrease) in Temporary Equity [Roll Forward]
Conversion of convertible preferred stock into common stock (in shares)	(34,942,503)
Conversion of convertible preferred stock into common stock	$ (415,258)
Ending balance (in shares) at Sep. 30, 2023	0
Ending balance at Sep. 30, 2023	$ 0
Beginning balance (shares) at Dec. 31, 2022		4,532,751
Beginning balance at Dec. 31, 2022	(111,294)	$ 1	19,374	(553)	(130,116)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Deemed dividend upon down round of common stock	0		1,209		(1,209)
Conversion of convertible preferred stock into common stock (in shares)		35,616,773
Conversion of convertible preferred stock into common stock	415,258	$ 3	415,255
Issuance of common stock (in shares)		18,706,240
Issuance of common stock	$ 310,402	$ 2	310,400
Exercise of vested stock options (in shares)	1,209,126	463,559
Exercise of vested stock options	$ 1,475		1,475
Vesting of early exercised stock options and founder shares (in shares)		506,861
Vesting of early exercised stock options and founder shares	722		722
Stock-based compensation	7,195		7,195
Other noncash compensation	199		199
Unrealized gain (loss) on investment securities	167			167
Net loss	(48,802)				(48,802)
Ending balance (shares) at Sep. 30, 2023		59,826,184
Ending balance at Sep. 30, 2023	$ 575,322	$ 6	755,829	(386)	(180,127)
Beginning balance (in shares) at Jun. 30, 2023	34,942,503
Beginning balance at Jun. 30, 2023	$ 415,258
Increase (Decrease) in Temporary Equity [Roll Forward]
Conversion of convertible preferred stock into common stock (in shares)	(34,942,503)
Conversion of convertible preferred stock into common stock	$ (415,258)
Ending balance (in shares) at Sep. 30, 2023	0
Ending balance at Sep. 30, 2023	$ 0
Beginning balance (shares) at Jun. 30, 2023		5,242,552
Beginning balance at Jun. 30, 2023	(135,489)	$ 1	25,803	(566)	(160,727)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Deemed dividend upon down round of common stock	0		1,209		(1,209)
Conversion of convertible preferred stock into common stock (in shares)		35,616,773
Conversion of convertible preferred stock into common stock	415,258	$ 3	415,255
Issuance of common stock (in shares)		18,706,240
Issuance of common stock	310,402	$ 2	310,400
Exercise of vested stock options (in shares)		60,844
Exercise of vested stock options	197		197
Vesting of early exercised stock options and founder shares (in shares)		199,775
Vesting of early exercised stock options and founder shares	335		335
Stock-based compensation	2,564		2,564
Other noncash compensation	66		66
Unrealized gain (loss) on investment securities	180			180
Net loss	(18,191)				(18,191)
Ending balance (shares) at Sep. 30, 2023		59,826,184
Ending balance at Sep. 30, 2023	$ 575,322	$ 6	$ 755,829	$ (386)	$ (180,127)

Condensed Statements of Conve_2

Condensed Statements of Convertible Preferred Stock and Stockholders’ Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Statement of Stockholders' Equity [Abstract]
Common stock issuance costs	$ 26,310		$ 26,310
Convertible preferred stock issuance costs		$ 406		$ 406

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash Flows from Operating Activities:
Net loss	$ (48,802)	$ (53,898)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,421	1,112
Loss on disposal of property and equipment	0	20
Stock-based compensation	7,195	4,219
Other noncash compensation	199	269
Issuance of common stock for license rights	0	6,548
Amortization of premium/(discount) on investment securities	(5,991)	519
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(1,026)	(731)
Accounts payable and accrued liabilities	1,765	929
Operating lease right-of-use assets and liabilities, net	(21)	121
Net cash used in operating activities	(45,260)	(40,892)
Cash Flows from Investing Activities:
Purchases of property and equipment	(31,811)	(6,296)
Purchases of investment securities	(292,489)	(50,082)
Sales and maturities of investment securities	177,530	104,448
Net cash provided by (used in) investing activities	(146,770)	48,070
Cash Flows from Financing Activities:
Proceeds from issuance of common stock in initial public offering, net of issuance costs	310,947	0
Proceeds from issuance of convertible preferred stock, net of issuance costs	0	159,684
Proceeds from exercise of vested and unvested common stock options	3,888	87
Repurchase of common stock	0	(1,876)
Net cash provided by financing activities	314,835	157,895
Net increase in cash, cash equivalents and restricted cash	122,805	165,073
Cash, cash equivalents and restricted cash, beginning of period	129,498	50,851
Cash, cash equivalents and restricted cash, end of period	252,303	215,924
Supplemental Disclosure of Noncash Activities:
Issuance of common stock for license rights	0	6,548
Vesting of common stock	722	620
Unpaid property and equipment purchases	6,487	1,335
Right-of-use assets and operating lease liabilities	0	2,345
Unpaid equity offering costs	545	335
Conversion of preferred stock to common stock upon initial public offering	415,258	0
Deemed dividend upon down round of equity offerings	$ 1,209	$ 4,550

Organization and Summary of Sig

Organization and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Organization and Summary of Significant Accounting Policies	Organization and Summary of Significant Accounting Policies Organization RayzeBio, Inc. (the “Company”) was incorporated in the state of Delaware on January 2, 2020 and is based in San Diego, California. The Company is building a vertically integrated radiopharmaceutical therapeutics (“RPT”) company. Reverse Stock Split On September 7, 2023, the Company effected a 1-for-5.141 reverse stock split of its common stock and the convertible preferred stock. The par value and the authorized shares of the common stock and the convertible preferred stock were not adjusted as a result of the reverse stock split. The accompanying condensed financial statements and notes to the condensed financial statements give retroactive effect to the reverse stock split for all periods presented. Initial Public Offering On September 19, 2023, the Company completed its initial public offering (“IPO”) in which the Company issued and sold 18,706,240 shares of common stock (including 2,591,640 shares of common stock in connection with the full exercise of the underwriters’ option to purchase additional shares) at an offering price to the public of $18.00 per share. Proceeds from the IPO, net of offering costs, were $310.4 million. In connection with the completion of the IPO, all outstanding shares of convertible preferred stock were converted into 35,616,773 shares of common stock. Emerging Growth Company Status The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 ("JOBS Act"). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act until such time as those standards apply to private companies. The Company has irrevocably elected to avail itself of this exemption from new or revised accounting standards, and therefore, will not be subject to the same new or revised accounting standards as other public companies that are not emerging growth companies. Use of Estimates The Company’s financial statements are prepared in accordance with U.S. generally accepted accounting principles (“GAAP”). The preparation of the Company’s financial statements requires it to make estimates and assumptions that impact the reported amounts of assets, liabilities and expenses and the disclosure of contingent assets and liabilities in the Company’s condensed financial statements and accompanying notes. The most significant estimates in the Company’s condensed financial statements relate to accruals for research and development expenses, stock-based compensation and other fair value measurements. These estimates and assumptions are based on current facts, historical experience and various other factors 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 recording of expenses that are not readily apparent from other sources. Actual results may differ materially and adversely from these estimates. To the extent there are material differences between the estimates and actual results, the Company’s future results of operations will be affected. Unaudited Interim Financial Information The accompanying condensed balance sheet as of September 30, 2023, the condensed statements of operations and comprehensive loss for the three and nine months ended September 30, 2023 and 2022, condensed statements of convertible preferred stock and stockholders’ equity (deficit) for the three and nine months ended September 30, 2023 and 2022 and condensed statements of cash flows for the nine months ended September 30, 2023 and 2022 and the related footnote disclosures are unaudited. In management’s opinion, the unaudited interim financial statements have been prepared on the same basis as the audited financial statements and include all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of the Company’s financial position as of September 30, 2023 and its results of operations for the three and nine months ended September 30, 2023 and 2022 required by GAAP for complete financial statements. The results for the three and nine months ended September 30, 2023 are not necessarily indicative of the results expected for the full fiscal year or any other interim period. These unaudited condensed financial statements should be read in conjunction with the audited consolidated financial statements and the notes thereto for the year ended December 31, 2022 included in the Company’s final prospectus dated September 14, 2023 filed with the Securities and Exchange Commission (the "SEC") on September 18, 2023 pursuant to Rule 424(b) under the Securities Act of 1933, as amended (the "Securities Act"). There have been no changes to the significant accounting policies disclosed in Note 1 to the consolidated financial statements for the years ended December 31, 2022 included in the Company’s final prospectus for the IPO filed pursuant to Rule 424(b)(4) under the Securities Actt with the SEC on September 18, 2023. Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board or other standard setting bodies that the Company adopt as of the specified effective date. The Company has evaluated recently issued accounting pronouncements and, based on its assessment, does not believe any will have a material impact on its unaudited condensed financial statements or related footnote disclosures. Liquidity and Capital Resources From its inception through September 30, 2023, the Company has devoted substantially all its resources and efforts to building its organization, developing its RPT discovery engine, identifying and developing potential drug candidates, preparing for and executing preclinical studies and clinical trials, acquiring technology, organizing and staffing the Company, business planning, establishing and securing its intellectual property portfolio, raising capital, building out its GMP manufacturing facility and providing general and administrative support for these operations. The Company has incurred net losses and negative cash flows from operations since inception and had an accumulated deficit of $180.1 million as of September 30, 2023. Since inception through September 30, 2023, the Company has funded its operations primarily with the net proceeds from the issuance of its convertible preferred stock and the issuance of common stock from the Company’s IPO. The Company expects to incur substantial operating losses for the next several years and will need to obtain additional financing in order to complete clinical trials and launch and commercialize any drug candidates for which it receives regulatory approval. The Company plans to continue to fund its losses from operations and capital funding needs through public or private equity or debt financings or other sources. If the Company is not able to secure adequate additional funding, the Company may be forced to make reductions in spending, extend payment terms with suppliers, liquidate assets where possible, or suspend or curtail planned programs. Any of these actions could materially harm the Company’s business, financial condition, results of operations and prospects. There can be no assurance that such financing will be available or will be at terms acceptable to the Company. As of September 30, 2023, the Company had cash, cash equivalents and short-term investment securities of $540.2 million, which will be sufficient to fund its planned operations for a period of at least 12 months from the issuance date of these condensed financial statements. Fair Value Measurements The accounting guidance defines fair value, establishes a consistent framework for measuring fair value and expands disclosure for each major asset and liability category measured at fair value on either a recurring or non-recurring basis. Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the accounting guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows: Level 1: Observable inputs such as quoted prices in active markets. Level 2: Inputs, other than the quoted prices in active markets that are observable either directly or indirectly. Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. The carrying value of the Company’s cash, cash equivalents, restricted cash, prepaid and other current assets, accounts payable and accrued liabilities are considered to be representative of their respective fair values due to the short-term nature of those instruments. Financial assets measured at fair value on a recurring basis consist of marketable securities. The fair value of marketable securities is based upon market prices quoted on the last day of the fiscal period or other observable market inputs. The Company obtains pricing information from its investment manager and generally determines the fair value of investment securities using standard observable inputs, including reported trades, broker/dealer quotes, bids and/or offers. The Company has no financial liabilities recorded at fair value on a recurring basis. None of the Company’s non-financial assets or liabilities are recorded at fair value on a non-recurring basis. No transfers between levels have occurred during the periods presented. The following tables summarize the Company’s financial instruments measured at fair value on a recurring basis (in thousands): Fair Value Measurements at Total Quoted Prices in Significant Significant As of September 30, 2023: Assets: Cash equivalents: Money market funds $ 220,045 $ 220,045 $ — $ — Commercial paper 7,478 — 7,478 — U.S. treasury securities 14,856 14,856 — — Total cash equivalents 242,379 234,901 7,478 — Short-term investments: Commercial paper 47,653 — 47,653 — Corporate debt securities 8,042 — 8,042 — U.S. agency securities 25,233 — 25,233 — U.S. treasury securities 207,277 207,277 — — Total short-term investments 288,205 207,277 80,928 — Total assets measured at fair value on a recurring basis $ 530,584 $ 442,178 $ 88,406 $ — As of December 31, 2022: Assets: Cash equivalents: Money market fund $ 9,691 $ 9,691 $ — $ — Commercial paper 106,042 — 106,042 — Corporate debt securities 7,677 — 7,677 — Total cash equivalents 123,410 9,691 113,719 — Short-term investments: Asset backed securities 105 — 105 — Commercial paper 85,732 — 85,732 — Corporate debt securities 16,661 — 16,661 — U.S. agency securities 15,351 — 15,351 — U.S. treasury securities 49,238 49,238 — — Total short-term investments 167,087 49,238 117,849 — Total assets measured at fair value on a recurring basis $ 290,497 $ 58,929 $ 231,568 $ — Cash, Cash Equivalents and Restricted Cash The Company considers all highly liquid investments with original maturities of three months or less when purchased to be cash equivalents. Cash and cash equivalents include cash in readily available checking accounts, money market funds, commercial paper, corporate debt securities and U.S. treasury securities. Restricted cash primarily represents money market accounts held as collateral in connection with the Company’s facility leases and is reported as a long-term asset in the accompanying condensed balance sheets. Cash, cash equivalents and restricted cash presented in the accompanying condensed statements of cash flows consist of the following (in thousands): September 30, 2023 2022 Cash and cash equivalents $ 251,964 $ 215,585 Restricted cash 339 339 Total $ 252,303 $ 215,924 Marketable Securities The Company’s marketable securities primarily consist of money market funds, asset backed securities, commercial paper, corporate debt securities, U.S. agency securities and U.S. treasury securities classified within cash and cash equivalents and short-term investments depending on their maturity at the time of purchase. The Company classifies marketable securities as available-for-sale, as the sale of such investments may be required prior to maturity to implement management strategies, and therefore has classified all marketable securities with maturity dates beyond three months at the date of purchase as current assets in the accompanying condensed balance sheets. As of September 30, 2023, the Company had no intent to sell any marketable securities prior to maturity. Marketable securities classified as available-for-sale are carried at fair value with the unrealized gains and losses included in other comprehensive loss as a component of stockholders’ equity (deficit) until realized. Any premium or discount arising at purchase is amortized and/or accreted to interest income as an adjustment to yield using the straight-line method over the life of the instrument. Realized gains and losses are calculated using the specific identification method and recorded as interest income or expense. The Company segments its portfolio based on the underlying risk profiles of their current securities being held. The Company regularly reviews the securities in an unrealized loss position and evaluates the current expected credit loss by considering factors such as historical experience, market data, issuer-specific factors, current and expected future economic conditions. The Company has determined there were no material declines in fair values of its marketable securities due to credit-related factors through September 30, 2023. The following tables summarize available-for-sale securities (in thousands): As of September 30, 2023 Maturity Amortized Unrealized Estimated Gains Losses Cash equivalents: Money market funds $ 220,045 $ — $ — $ 220,045 Commercial paper 1 year or less 7,477 1 — 7,478 U.S. treasury securities 1 year or less 14,854 2 — 14,856 Total cash equivalents 242,376 3 — 242,379 Short-term investments: Commercial paper 2 years or less 47,701 — (48) 47,653 Corporate debt securities 2 years or less 8,078 1 (37) 8,042 U.S. agency securities 2 years or less 25,323 — (90) 25,233 U.S. treasury securities 2 years or less 207,492 4 (219) 207,277 Total short-term investments 288,594 5 (394) 288,205 Total $ 530,970 $ 8 $ (394) $ 530,584 As of December 31, 2022 Maturity Amortized Unrealized Estimated Gains Losses Cash equivalents: Money market funds $ 9,691 $ — $ — $ 9,691 Commercial paper 1 year or less 106,014 28 — 106,042 Corporate debt securities 1 year or less 7,677 — — 7,677 Total cash equivalents 123,382 28 — 123,410 Short-term investments: Asset backed securities 2 years or less 105 — — 105 Commercial paper 1 year or less 85,746 33 (47) 85,732 Corporate debt securities 2 years or less 16,699 2 (40) 16,661 U.S. agency securities 2 years or less 15,353 10 (12) 15,351 U.S. treasury securities 2 years or less 49,765 — (527) 49,238 Total short-term investments 167,668 45 (626) 167,087 Total $ 291,050 $ 73 $ (626) $ 290,497 The amortized cost and estimated fair value in the table above excludes $0.7 million and $0.5 million of accrued interest receivable included in prepaid expenses and other current assets in the accompanying condensed balance sheets as of September 30, 2023 and December 31, 2022, respectively. As of September 30, 2023, 47 of the Company’s available-for-sale debt securities with a fair market value of $232.8 million were in a gross unrealized loss position of $0.4 million. Of those, none of the Company’s available-for-sale debt securities were in a continuous loss position for greater than 12 months. As of December 31, 2022, 29 of the Company’s available-for-sale debt securities with a fair market value of $101.6 million were in a gross unrealized loss position of $0.6 million. Of those, 8 of the Company’s available-for-sale debt securities with a fair market value of $34.3 million and a gross unrealized loss position of $0.5 million have been in a continuous loss position for greater than 12 months. The Company considers the decline in market value for the securities to be primarily attributable to current economic conditions and interest rate adjustments, rather than credit-related factors and does not intend to sell any securities prior to maturity. Concentrations of Credit Risk Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents, short-term investments and restricted cash. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company is exposed to credit risk in the event of default by the institutions holding its cash, cash equivalents, restricted cash and any marketable securities to the extent of the amounts recorded in the condensed balance sheets. Deferred Offering Costs The Company capitalizes certain legal, accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated. After the consummation of the equity financing, these costs are recorded in members’ deficit as a reduction of additional paid-in capital or the associated preferred unit account, as applicable. In the event the offering is terminated, all capitalized deferred offering costs, currently recorded within other current assets, will be expensed immediately as a charge to operating expenses in the condensed statement of operations and comprehensive loss. As of September 30, 2023 and December 31, 2022, the Company had no deferred offering costs. Research and Development Costs All costs for research and development are expensed in the period incurred. Research and development costs primarily consist of salaries and related expenses for personnel, stock-based compensation expense, outside service providers, facilities costs, fees paid to consultants and other professional services, external research and development costs incurred under agreements with contract research organizations, license and collaboration fees, supplies used in research and development and facilities, depreciation and other allocated expenses. Payments made prior to the receipt of goods or services to be used in research and development are capitalized until the related goods are delivered or services performed. The Company has entered into various research and development contracts with research organizations and other companies. Payments for these activities are based on the terms of the individual agreements, which may differ from the pattern of costs incurred, and payments made in advance of performance are reflected in the accompanying condensed balance sheets as prepaid expenses and other current assets. The Company records accruals for estimated costs incurred for ongoing research and development activities. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the services, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates may be made in determining the prepaid or accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates. Historically, there have been no material differences between the Company’s estimates and the amounts actually incurred. Segment Reporting Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company and its chief operating decision-maker view the Company’s operations and manage its business in one operating segment. Net Loss Per Share Basic net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding for the period, without consideration for potentially dilutive securities. The Company has excluded weighted-average unvested shares of 1,275,436 shares and 1,230,860 shares, from the weighted-average number of common shares outstanding for the three months ended September 30, 2023 and 2022, respectively, and 1,143,588 shares and 1,440,400 shares, from the weighted-average number of common shares outstanding for the nine months ended September 30, 2023 and 2022, respectively. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common shares and dilutive common stock equivalents outstanding for the period determined using the treasury-stock and if-converted methods. Dilutive common stock equivalents are comprised of convertible preferred stock, unvested common stock subject to repurchase and options outstanding under the Company’s stock option plans. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding as inclusion of the potentially dilutive securities would be anti-dilutive. Potentially dilutive securities not included in the calculation of diluted net loss per share, because to do so would be anti-dilutive, are as follows (in common stock equivalent shares): Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Convertible preferred stock outstanding – 35,543,204 – 35,543,204 Common stock options 4,257,580 2,983,404 4,257,580 2,983,404 Unvested common stock 1,221,005 1,129,250 1,221,005 1,129,250 Total 5,478,585 39,655,858 5,478,585 39,655,858

Balance Sheet Details

Balance Sheet Details	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheet Details	Balance Sheet Details Property and equipment, net consist of the following (in thousands): September 30, December 31, Laboratory equipment $ 8,989 $ 7,484 Computer equipment and software 304 185 Furniture and fixtures 522 522 Leasehold improvements 163 163 Construction in progress 43,012 8,603 52,990 16,957 Less accumulated depreciation (3,294) (1,873) Total $ 49,696 $ 15,084 The Company recognized depreciation expense of $0.5 million and $1.4 million for the three and nine months ended September 30, 2023, respectively and $0.4 million and $1.1 million for the three and nine months ended September 30, 2022, respectively. Accrued liabilities consist of the following (in thousands): September 30, December 31, Accrued compensation $ 3,076 $ 2,621 Accrued research and development 3,480 3,209 Accrued property and equipment purchases 6,267 471 Other accrued liabilities 787 390 Total $ 13,610 $ 6,691

Commitments, Contingencies and

Commitments, Contingencies and Collaboration and License Agreements	9 Months Ended
	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments, Contingencies and Collaboration and License Agreements	Commitments, Contingencies and Collaboration and License Agreements Operating Leases The Company leases office and laboratory space for its current headquarters in San Diego, California under a non-cancelable operating lease expiring in October 2028 (the “Morehouse Lease”). The Morehouse Lease contains an option to extend the lease for a period of five years, which was not included in the determination of the lease term as it was not reasonably certain that the Company would exercise this option. The Morehouse Lease requires a standby letter of credit of $0.1 million, which is secured by a money market account that is classified as restricted cash in the accompanying condensed balance sheets. The restricted cash is classified as long-term as the underlying funds are required as collateral for the standby letter of credit for a period of greater than 12 months from the balance sheet date. In November 2021, the Company entered into a non-cancelable operating lease for 63,000 square feet of industrial space located in Indianapolis, Indiana for the construction of a GMP manufacturing facility (the “Indianapolis Lease”). The initial lease term is from March 2022 through April 2032 with an option to extend the lease for a period of five years. Monthly base rental payments due under the Indianapolis Lease commenced in March 2022 and escalate throughout the lease term. The Indianapolis Lease includes certain lease incentives and tenant improvement allowances and the Company is subject to additional charges for operating expenses. Under the terms of the Indianapolis Lease, the Company provided the lessor with an irrevocable letter of credit in the amount of $0.2 million, which is secured by a money market account that is classified as restricted cash in the accompanying condensed balance sheets. The restricted cash is classified as long-term as the underlying funds are required as collateral for the standby letter of credit for a period of greater than 12 months from the balance sheet date. The Indianapolis Lease commenced in March 2022 and the Company recorded a ROU asset of $2.3 million and operating lease liability of $2.4 million, net of lease incentives. Information related to the Company’s operating leases is as follows (in thousands): Three Months Ended Nine Months Ended 2023 2022 2023 2022 Operating lease expense $ 494 $ 495 $ 1,482 $ 1,443 Variable lease expenses $ 305 $ 173 $ 845 $ 502 Cash paid for amounts included in the measurement of lease liabilities $ 501 $ 487 $ 1,503 $ 1,322 The following table presents non-cancelable future minimum lease payments under operating leases (in thousands, except discount rate and remaining term): September 30, Periods ending December 31: 2023 (remaining 3 months) $ 506 2024 2,070 2025 2,132 2026 2,196 2027 2,261 Thereafter 3,414 Total minimum lease payments 12,579 Less: amount representing interest (2,855) Total operating lease liabilities 9,724 Less: current portion of lease liabilities (1,266) Operating lease liabilities, net of current portion $ 8,458 Weighted-average discount rate 8.6 % Weighted-average remaining term 6.0 years License and Research Collaboration Agreement with Peptidream, Inc. On August 3, 2020, the Company and PeptiDream, Inc. (“PeptiDream”) entered into a license and research collaboration agreement (the “PeptiDream Agreement”) to engage in certain collaborative research activities relating to the identification, discovery, validation, and optimization of novel peptide compounds, following which the Company will have the right to develop and commercialize novel peptide-drug conjugates containing one or more compounds arising out of such collaborative research activities. The initial research term under the PeptiDream Agreement is two years and the Company may extend the research term for one year. The PeptiDream Agreement also contains a research plan under which each party is solely responsible for their own costs incurred. Pursuant to the PeptiDream Agreement, PeptiDream granted the Company a non-transferable, sublicensable, worldwide, royalty and fee-bearing exclusive commercial license to certain licensed intellectual property rights. PeptiDream also granted the Company a non-exclusive, non-transferable, non-sublicensable, worldwide, non-commercial license to certain intellectual property rights for research purposes only, solely to the extent necessary for the Company to perform its collaboration activities. The Company granted PeptiDream a non-exclusive, non-transferable, non-sublicensable, worldwide license to certain intellectual property rights, solely to the extent necessary for PeptiDream to perform its collaboration activities. As consideration for the rights and licenses provided, the Company agreed to issue its common shares to PeptiDream upon the closing of each preferred stock offering such that PeptiDream will maintain, on a fully diluted basis, a 5% ownership interest in the Company (the “Right to Future Equity”). The Right to Future Equity terminates upon the earliest of (i) termination of the PeptiDream Agreement in accordance with its terms, (ii) consummation of a change of control of the Company or (iii) consummation of an underwritten public offering of the Company’s common stock. The Company evaluated the terms of the Right to Future Equity and determined the right is a derivative that is not separable from the initial shares of common stock issued under the PeptiDream Agreement and in conjunction with the Company’s Series A preferred stock financing, and therefore, the derivative is embedded and will not require bifurcation as there is no net settlement. The Company will recognize the fair value of any common stock issued under the Right to Future Equity at the time of issuance. In addition to the equity grants, the Company has agreed to pay development milestones for each collaboration target and sales milestones of up to an aggregate of $380.0 million. The Company has agreed to pay PeptiDream a mid to high single-digit percentage royalty on net sales of licensed products, subject to reduction under certain circumstances. In addition, if the Company chooses to sublicense the license to any third parties, the Company agreed to pay to PeptiDream a mid single-digit to mid-twenties percentage of all sublicensing revenue. No amounts have been incurred or paid as of September 30, 2023. Unless earlier terminated, the PeptiDream Agreement will expire on the first to occur of (a) the instance that, at any time from and after the expiration of the research term, there are no selected conjugates under active development or commercialization by the Company or (b) on a licensed product-by-licensed product and country-by-country basis upon the expiration of the applicable royalty term for such licensed product. The applicable royalty term shall begin on the date of first commercial sale of such licensed product in such country and end on the later of (i) expiration of the last-to-expire royalty claim, (ii) expiration of the regulatory exclusivity period with respect to such licensed product in such country, or (iii) 10 years. Upon expiration of the PeptiDream Agreement pursuant to clause (b) above, the commercial licenses granted to the Company will become irrevocable and fully paid-up with respect to such licensed product and country. The Company has the right to terminate the PeptiDream Agreement, without cause, by giving 60 days’ advance written notice to PeptiDream, (a) in its entirety, (b) with respect to one or more collaboration target-specific aspects of the research plan, or (c) after the research term, with respect to one or more collaboration targets. Further, the PeptiDream Agreement may be terminated at any time during the term (i) upon written notice by either party upon a material uncured breach, (ii) by either party upon the filing or institution of bankruptcy, reorganization, liquidation, or receivership proceedings with respect to the other party, or upon an assignment of a substantial portion of the other party’s assets for the benefit of its creditors, and (iii) by PeptiDream immediately upon written notice to the Company in the event that the Company, or through an affiliate or sublicensee, directly or through assistance from a third party commences or participates in any administrative, judicial or similar proceeding challenging the validity, enforceability and/or patentability of any of PeptiDream’s patents or licensed technology, subject to certain exceptions. In 2020, 2021 and 2022, the Company issued 1,187,980 shares, 286,656 shares and 851,943 shares, respectively, of its common stock to PeptiDream in conjunction with its Series A, Series B, Series C and Series D convertible preferred stock financings. In connection with the common stock issuances to PeptiDream the Company recognized $6.5 million for the three and nine months ended September 30, 2022, of fair value of the common stock issuances within research and development expense in the accompanying condensed statements of operations. No shares were issued to PeptiDream during the three and nine months ended September 30, 2023. On August 9, 2022, the Company entered into an amendment to the PeptiDream Agreement (the “PeptiDream Amendment”). Pursuant to the PeptiDream Amendment, the Company (i) terminated an existing collaboration target and replaced it with a new collaboration target, (ii) extended the research term to four years, (iii) granted PeptiDream an exclusive option to develop, manufacture and commercialize the licensed product in a certain country, solely at PeptiDream’s expense, provided that PeptiDream provides notice of such option exercise before a certain clinical period. Pursuant to the PeptiDream Amendment, (iv) granted PeptiDream (a) a non-transferable, sublicensable, royalty-free, fully paid-up, exclusive license to certain background technology and certain collaboration technology to exploit such licensed product in a certain country and (b) a royalty-free, fully paid-up, non-exclusive license to any other know-how the Company or its affiliates control or that the Company or its affiliates come to control during the term of the PeptiDream Agreement that relates to such licensed product and is necessary or useful for the exercise of the license. Pursuant to the PeptiDream Amendment, PeptiDream has the right to grant a license to certain background technology and certain collaboration technology to any of its affiliates or any third party, subject to certain conditions. On September 14, 2023, in connection with the IPO, the Right to Future Equity terminated and the Company is no longer required to issue shares to PeptiDream to maintain a 5% ownership in the Company. Research Collaboration and License Agreement with Nimble Therapeutics, Inc. In February 2021, as amended in September and November 2021, the Company and Nimble Therapeutics, Inc. (“Nimble”) entered into a research collaboration and license agreement (the “Nimble Agreement”) to collaborate on certain preclinical development activities with the goal of identifying binding peptides to certain collaboration targets. The collaboration may involve up to a fixed number of option targets, which the Company has the right to nominate during a specified time period. The Company has agreed that after a certain stage of each research plan, the Company is responsible for and has decision-making authority with respect to all development, manufacturing and commercialization of program molecules and program products at its sole cost and expense. Pursuant to the Nimble Agreement, Nimble granted the Company a non-exclusive, sublicensable (subject to certain exclusions) license to certain of its existing and arising patents and know-how, solely to the extent necessary to make, have made, use, sell, offer for sale, export, import and fully exploit certain program molecules and program products, in the diagnosis, screening or treatment of one of more human diseases by introducing into the human body a peptide molecule targeting a collaboration target coupled to any radioactive molecule worldwide. Under the Nimble Agreement, the Company granted Nimble a non-exclusive, royalty-free, worldwide license to certain of its intellectual property solely for the purpose of Nimble’s performance of its assigned activities under each research plan and program. The Company paid Nimble an upfront payment of $0.8 million for the primary collaboration target and has agreed to pay Nimble (i) up to an aggregate of $201.7 million upon the attainment of certain discovery, development and sales milestones and (ii) a mid-single digit royalty on net product sales for the first target. The Company has also agreed to make the following payments in total if it nominates the maximum number of additional optional collaboration targets permitted under the Nimble Agreement: (i) up to an aggregate of $897.5 million, which consists of an upfront payment, payments upon the attainment of certain discovery, development and first commercial sales milestones, and certain net sales milestones, and (ii) a mid-single digit royalty on net product sales, subject to reduction under certain circumstances. In addition, the Company has agreed to pay Nimble up to a low double digit percentage of certain licensing consideration it receives. The Nimble Agreement will expire on a program product-by-program product and country-by-country basis on the date of the expiration of all applicable royalty obligations. Both parties have the right to terminate the Nimble Agreement for an uncured material breach or insolvency of the other party. The Company has the unilateral right to terminate the Nimble Agreement in its entirety upon 90 days prior written notice. At the inception of the Nimble Agreement, the Company capitalized the $0.8 million upfront payment to Nimble and will amortize such amount to research and development expense over the estimated performance period of Nimble’s assigned activities under the Nimble Agreement. No material fair value was assigned to the license given its early stage of development. As of September 30, 2023, there was no unamortized balance to be recognized. For certain costs incurred by Nimble in connection with the Nimble Agreement, the Company reimbursed Nimble $0 and $0.1 million for the three months ended September 30, 2023 and 2022, respectively, and $0.2 million and $0.3 million for the nine months ended September 30, 2023 and 2022, respectively. License Agreement with Ablaze Pharmaceuticals In May 2021, as amended in November 2021 and June 2023, the Company entered into a license agreement (the “Ablaze Agreement”) under which the Company granted Ablaze an exclusive, royalty-bearing and sublicenseable (under certain circumstances) license to certain of the Company’s intellectual property to develop, make, have made, use, sell, offer for sale, import and otherwise commercialize a certain number of the Company’s proprietary products in China, Hong Kong, Macau and Taiwan (“greater China”) for all therapeutic, prophylactic and diagnostic uses, and a right of first negotiation to license up to a certain number of additional products from the Company. Upon completion of certain activities by the Company, Ablaze shall have a designated period of time to decide whether to select such product as a product under this Ablaze Agreement. Ablaze is solely responsible for the development, manufacturing and commercialization of all products covered by the Ablaze Agreement. The maximum number of selected products under the Ablaze Agreement is limited to a certain number and Ablaze’s right to select products will expire upon the earlier of (a) Ablaze selecting the maximum number of products allowed to be selected under the Ablaze Agreement; and (b) the Company presenting to Ablaze a certain number of products for consideration by Ablaze to license. Additionally, pursuant to the Ablaze Agreement, Ablaze granted the Company an exclusive, royalty-free and sublicensable (under certain conditions) license to certain of its intellectual property to develop, manufacture and commercialize certain of the Company’s proprietary products for all therapeutic, prophylactic and diagnostic uses outside of greater China. No upfront payments were required under the Ablaze Agreement. Ablaze has agreed to pay the Company: (i) up to an aggregate of $70.0 million per product upon the attainment of certain development and net sales milestones, and (ii) a mid to high-single digit royalty on net product sales in greater China, subject to certain potential royalty reductions. In addition, Ablaze has agreed to pay the Company up to a percentage in the mid-teens to mid-twenties of certain sublicense revenue it receives, depending on the time when the sublicense agreement is executed. As of September 30, 2023, no payments have been received from Ablaze. Unless earlier terminated, the Ablaze Agreement will remain in effect on a product-by-product basis and region-by-region basis, until the expiration of the royalty term for such product in such region in greater China. After the expiration (but not early termination) of the term of the Ablaze Agreement for a particular product in a particular region in greater China, the licenses granted by the Company to Ablaze will continue and become fully paid, royalty-free, perpetual and irrevocable with respect to such product in such region. Under the Ablaze Agreement, either party may terminate if there is an uncured material breach. Either party may terminate the Ablaze Agreement immediately upon written notice to the other party if the other party undergoes certain bankruptcy-related events. Ablaze may terminate the Ablaze Agreement on a product-by-product and region-by-region basis by providing 60 days written notice to the Company. The Company may terminate the Ablaze Agreement in its entirety upon written notice to Ablaze if Ablaze or its affiliates or sublicensees commences a legal action challenging the validity, enforceability or scope of any of the Company’s licensed patents anywhere in the world. Collaboration and Supply Agreement with Niowave, Inc .

Convertible Preferred Stock and

Convertible Preferred Stock and Stockholders’ Equity (Deficit)	9 Months Ended
	Sep. 30, 2023
Equity [Abstract]
Convertible Preferred Stock and Stockholders’ Equity (Deficit)	Convertible Preferred Stock and Stockholders’ Equity (Deficit) Convertible Preferred Stock The authorized, issued and outstanding shares of convertible preferred stock as of December 31, 2022 consist of the following (in thousands, except share amounts): Shares Shares Issued Liquidation Carrying Series A 45,000,000 8,753,147 $ 41,512 $ 45,937 Series B 46,666,672 9,077,342 96,860 104,270 Series C 23,999,996 4,668,338 99,628 105,702 Series D 63,972,982 12,443,676 159,755 159,349 Total 179,639,650 34,942,503 $ 397,755 $ 415,258 Upon closing of the IPO in September 2023, all outstanding shares of the Company's convertible preferred stock automatically converted into 35,616,773 shares of common stock. As a result, there were no shares of convertible preferred stock issued and outstanding as of September 30, 2023. In August 2022, the Company entered into a Series D preferred stock purchase agreement with new and existing investors, pursuant to which it issued, in August and September 2022, an aggregate of 12,443,676 shares of its Series D convertible preferred stock at $12.83824 per share for gross proceeds of $159.8 million. The issuance of the Series D convertible preferred stock triggered the anti-dilution protection provision for Series C stockholders. As a result, the Company recorded a $4.6 million deemed dividend for the change in fair value of the Series C convertible preferred stock before and after the anti-dilution adjustment. The fair value of the Series C convertible preferred stock was determined using a “with-and-without” model under which the equity value of the Company was allocated using a hybrid method, whereby the enterprise value in the IPO scenario is allocated to each class of shares using the fully-diluted shares outstanding and whereby the enterprise value in the non-IPO scenario is allocated using an OPM to reflect the full distribution of possible non-IPO outcomes, both before and after the anti-dilution adjustment. The following table summarizes information about the significant Level 3 unobservable inputs used to estimate the fair value of the Company’s preferred stock at the modification date: Risk-free interest rate 3.45 % Expected volatility 80.0 % Expected term (in years) 2.0 Expected dividend yield 0.0 % In September 2023, the IPO triggered the anti-dilution protection provision for the Series C stockholders. As a result, the Company recorded a $1.2 million deemed dividend for the value of the anti-dilution protection. The value was determined as the difference between fair values of two financial instruments, the shares of common stock into which the preferred stock converted based on the adjusted conversion rates (determined using the IPO price of $18.00 per share), and the value of the common stock that preferred stock would have converted into upon completion of the IPO, had there not been a provision for anti-dilution. Founders Stock From April to July 2020, in conjunction with the founding of the Company, an aggregate of 1,884,213 shares of common stock were issued to the founders (the “Founders Stock”) at prices up to $0.005141 per share. At issuance, 1,167,087 shares of Founders Stock were fully vested and 717,126 shares of Founders Stock were subject to vesting over a period of up to four years. As of September 30, 2023 and December 31, 2022, 178,761 shares and 313,230 shares, respectively, of Founders Stock were unvested and subject to repurchase by the Company at the lower of the original cost or the fair value of the stock at the time of repurchase. As of September 30, 2023 and December 31, 2022, the repurchase liability for the Founders Stock was $1,000 and $2,000, respectively. For accounting purposes, unvested shares of common stock are not considered outstanding until they vest. In February 2022, the Company entered into a stock purchase agreement to repurchase 194,514 shares of common stock from a stockholder at a cash purchase price of $9.56226 per share. The repurchase was completed using cash on hand and the shares were retired upon reacquisition. The common stock was originally issued at par value and the excess of the repurchase price over the par value was charged to accumulated deficit. Equity Incentive Plans In July 2020, the Company adopted the RayzeBio, Inc. 2020 Equity Incentive Plan (as amended, the “2020 Plan”), which provides for the grant of incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, and other awards to its employees, members of its board of directors and consultants. The Company will not grant any additional awards under the 2020 Plan after the effectiveness of the 2023 Plan. In September 2023, the Company’s board of directors adopted and stockholders approved the 2023 Equity Incentive Plan (the “2023 Plan” and together with the 2020 Plan, the “Plans”). The 2023 Plan became effective on September 14, 2023. Under the 2023 Plan, the Company may grant stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, performance awards and other forms of awards to employees, directors and consultants of the Company, and employees and consultants of the Company’s affiliates. A total of 6,000,000 new shares of common stock were approved to be initially reserved for issuance under the 2023 Plan. The number of shares of common stock reserved for issuance under the 2023 Plan will automatically increase on January 1 of each year, beginning on January 1, 2024, and continuing through and including January 1, 2033, by 5% of the total number of shares of common stock outstanding on December 31 of the immediately preceding calendar year, or a lesser number of shares determined by the Company’s board of directors prior to the applicable January 1. A summary of the Company’s unvested shares and unvested stock liability, including unvested Founders Stock, is as follows (in thousands, except share data): Number of Unvested Balance at December 31, 2022 982,299 $ 929 Early exercised shares 745,567 2,413 Vested shares (506,861) (722) Balance at September 30, 2023 1,221,005 $ 2,620 A summary of the Company’s stock option activity is as follows (in thousands, except share and per share data): Number of Weighted- Weighted- Aggregate Balance at December 31, 2022 4,674,131 $ 3.07 9.47 $ 21,702 Granted 879,628 $ 6.71 Exercised (1,209,126) $ 3.22 Cancelled (87,053) $ 2.99 Balance at September 30, 2023 4,257,580 $ 3.78 8.97 $ 78,411 Vested and expected to vest at September 30, 2023 4,257,580 $ 3.78 8.97 $ 78,411 Exercisable at September 30, 2023 4,219,723 $ 3.66 8.96 $ 78,251 Stock-Based Compensation Expense The assumptions used in the Black-Scholes option pricing model to determine the fair value of stock option grants were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Risk-free interest rate 4.47% – 4.63% —% 3.41% – 4.63% 1.58% – 2.93% Expected volatility 93.8% – 94.7% —% 88.9% – 94.7% 81.9% – 84.5% Expected term (in years) 5.77 – 6.07 0.00 5.77 – 6.07 6.03 – 10.00 Expected dividend yield 0.0% 0.0% 0.0% 0.0% Risk-free interest rate . The risk-free interest rate is based on the U.S. Treasury yield in effect at the time of grant for zero coupon U.S. Treasury notes with maturities similar to the expected term of the awards. Expected volatility . Given the Company's limited stock price volatility data for its common stock, the expected volatility assumption is based on volatilities of a peer group of similar companies whose share prices are publicly available. The peer group was developed based on companies in the biotechnology industry. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available. Expected term . The expected term represents the period of time that options are expected to be outstanding. Because the Company does not have historical exercise behavior, it determines the expected life assumption using the simplified method, for employees, which is an average of the contractual term of the option and its vesting period. The expected term for nonemployee options is generally the contractual term. Expected dividend yield . The Company bases the expected dividend yield assumption on the fact that it has never paid cash dividends and has no present intention to pay cash dividends and, therefore, used an expected dividend yield of zero. 2023 Employee Stock Purchase Plan In September 2023, the Company’s board of directors adopted and stockholders approved and adopted the 2023 Employee Stock Purchase Plan (the “ESPP”). The ESPP became effective on September 14, 2023. The ESPP permits participants to purchase common stock through payroll deductions of up to a specified percentage of their eligible compensation. A total of 600,000 shares of common stock were approved to be initially reserved for issuance under the ESPP. The number of shares of common stock reserved for issuance under the ESPP will automatically increase on January 1 of each calendar year, beginning on January 1, 2024 and continuing through and including January 1, 2033, by the lesser of (1) 1% of the total number of shares of common stock outstanding on December 31 of the preceding calendar year, (2) 1,200,000 shares, and (3) a number of shares determined by the Company’s board of directors that is less than the amount set forth in clauses (1) and (2). Employees automatically enrolled in the ESPP upon its effective date. The ESPP is considered a compensatory plan as defined by the authoritative guidance for stock-based compensation. Stock-based compensation expense attributable to the ESPP was $0 for the three and nine months ended September 30, 2023 and no funds had been withheld from employees in connection with the ESPP. Stock-based compensation expense has been reported in the condensed statements of operations and comprehensive loss as follows (in thousands): Three Months Ended Nine Months Ended 2023 2022 2023 2022 Research and development $ 1,063 $ 757 $ 3,023 $ 2,219 General and administrative 1,501 690 4,172 2,000 Total $ 2,564 $ 1,447 $ 7,195 $ 4,219 The weighted-average grant date fair value per share of option grants for the three and nine months ended September 30, 2023 was $8.86 and $8.36, respectively, and for the three and nine months ended September 30, 2022 $0 and $7.11, respectively. No options were granted for the three months ended September 30, 2022. As September 30, 2023, total unrecognized stock-based compensation cost was $26.1 million, which is expected to be recognized over a remaining weighted-average period of approximately 2.7 years. The total intrinsic value of stock options exercised for the three and nine months ended September 30, 2023 was $1.9 million and $9.8 million, respectively. The total intrinsic value of stock options exercised for the three and nine months ended September 30, 2022 was $0 and $0.4 million, respectively. Common Stock Reserved for Future Issuance Common stock reserved for future issuance consists of the following: September 30, December 31, Conversion of preferred stock — 35,543,204 Common stock options outstanding 4,257,580 4,674,131 Shares available for issuance under the Plans 6,006,598 799,173 Shares available for purchase under the ESPP 600,000 — Total 10,864,178 41,016,508

401(k) Plan

401(k) Plan	9 Months Ended
	Sep. 30, 2023
Compensation Related Costs [Abstract]
401(k) Plan	401(k) Plan In January 2021, the Company adopted a defined contribution 401(k) plan available to eligible employees. Employee contributions are voluntary and are determined on an individual basis, limited to the maximum amount allowable under federal tax regulations. The Company, at its discretion, may make certain matching contributions to the 401(k) plan. As of September 30, 2023, the Company has not made any matching contributions.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2023
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events The Company evaluated subsequent events through the date on which these financial statements were issued to ensure that these condensed financial statements include appropriate disclosure of events both recognized in the financial statements as of September 30, 2023 and events which occurred subsequently but not recognized in the financial statements. No subsequent events have occurred that require disclosure.

Organization and Summary of S_2

Organization and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates
Unaudited Interim Financial Information	Unaudited Interim Financial Information The accompanying condensed balance sheet as of September 30, 2023, the condensed statements of operations and comprehensive loss for the three and nine months ended September 30, 2023 and 2022, condensed statements of convertible preferred stock and stockholders’ equity (deficit) for the three and nine months ended September 30, 2023 and 2022 and condensed statements of cash flows for the nine months ended September 30, 2023 and 2022 and the related footnote disclosures are unaudited. In management’s opinion, the unaudited interim financial statements have been prepared on the same basis as the audited financial statements and include all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of the Company’s financial position as of September 30, 2023 and its results of operations for the three and nine months ended September 30, 2023 and 2022 required by GAAP for complete financial statements. The results for the three and nine months ended September 30, 2023 are not necessarily indicative of the results expected for the full fiscal year or any other interim period. These unaudited condensed financial statements should be read in conjunction with the audited consolidated financial statements and the notes thereto for the year ended December 31, 2022 included in the Company’s final prospectus dated September 14, 2023 filed with the Securities and Exchange Commission (the "SEC") on September 18, 2023 pursuant to Rule 424(b) under the Securities Act of 1933, as amended (the "Securities Act").
Recent Accounting Pronouncements	Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board or other standard setting bodies that the Company adopt as of the specified effective date. The Company has evaluated recently issued accounting pronouncements and, based on its assessment, does not believe any will have a material impact on its unaudited condensed financial statements or related footnote disclosures.
Liquidity and Capital Resources	Liquidity and Capital ResourcesFrom its inception through September 30, 2023, the Company has devoted substantially all its resources and efforts to building its organization, developing its RPT discovery engine, identifying and developing potential drug candidates, preparing for and executing preclinical studies and clinical trials, acquiring technology, organizing and staffing the Company, business planning, establishing and securing its intellectual property portfolio, raising capital, building out its GMP manufacturing facility and providing general and administrative support for these operations. The Company has incurred net losses and negative cash flows from operations since inception and had an accumulated deficit of $180.1 million as of September 30, 2023. Since inception through September 30, 2023, the Company has funded its operations primarily with the net proceeds from the issuance of its convertible preferred stock and the issuance of common stock from the Company’s IPO. The Company expects to incur substantial operating losses for the next several years and will need to obtain additional financing in order to complete clinical trials and launch and commercialize any drug candidates for which it receives regulatory approval. The Company plans to continue to fund its losses from operations and capital funding needs through public or private equity or debt financings or other sources. If the Company is not able to secure adequate additional funding, the Company may be forced to make reductions in spending, extend payment terms with suppliers, liquidate assets where possible, or suspend or curtail planned programs. Any of these actions could materially harm the Company’s business, financial condition, results of operations and prospects. There can be no assurance that such financing will be available or will be at terms acceptable to the Company.
Fair Value Measurements	Fair Value Measurements The accounting guidance defines fair value, establishes a consistent framework for measuring fair value and expands disclosure for each major asset and liability category measured at fair value on either a recurring or non-recurring basis. Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the accounting guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows: Level 1: Observable inputs such as quoted prices in active markets. Level 2: Inputs, other than the quoted prices in active markets that are observable either directly or indirectly. Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. The carrying value of the Company’s cash, cash equivalents, restricted cash, prepaid and other current assets, accounts payable and accrued liabilities are considered to be representative of their respective fair values due to the short-term nature of those instruments.
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash The Company considers all highly liquid investments with original maturities of three months or less when purchased to be cash equivalents. Cash and cash equivalents include cash in readily available checking accounts, money market funds, commercial paper, corporate debt securities and U.S. treasury securities.
Marketable Securities	Marketable Securities The Company’s marketable securities primarily consist of money market funds, asset backed securities, commercial paper, corporate debt securities, U.S. agency securities and U.S. treasury securities classified within cash and cash equivalents and short-term investments depending on their maturity at the time of purchase. The Company classifies marketable securities as available-for-sale, as the sale of such investments may be required prior to maturity to implement management strategies, and therefore has classified all marketable securities with maturity dates beyond three months at the date of purchase as current assets in the accompanying condensed balance sheets. As of September 30, 2023, the Company had no intent to sell any marketable securities prior to maturity. Marketable securities classified as available-for-sale are carried at fair value with the unrealized gains and losses included in other comprehensive loss as a component of stockholders’ equity (deficit) until realized. Any premium or discount arising at purchase is amortized and/or accreted to interest income as an adjustment to yield using the straight-line method over the life of the instrument. Realized gains and losses are calculated using the specific identification method and recorded as interest income or expense.
Concentrations of Credit Risk	Concentrations of Credit Risk Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents, short-term investments and restricted cash. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company is exposed to credit risk in the event of default by the institutions holding its cash, cash equivalents, restricted cash and any marketable securities to the extent of the amounts recorded in the condensed balance sheets.
Deferred Offering Costs	Deferred Offering Costs The Company capitalizes certain legal, accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated. After the consummation of the equity financing, these costs are recorded in members’ deficit as a reduction of additional paid-in capital or the associated preferred unit account, as applicable. In the event the offering is terminated, all capitalized deferred offering costs, currently recorded within other current assets, will be expensed immediately as a charge to operating expenses in the condensed statement of operations and comprehensive loss.
Research and Development Costs	Research and Development Costs All costs for research and development are expensed in the period incurred. Research and development costs primarily consist of salaries and related expenses for personnel, stock-based compensation expense, outside service providers, facilities costs, fees paid to consultants and other professional services, external research and development costs incurred under agreements with contract research organizations, license and collaboration fees, supplies used in research and development and facilities, depreciation and other allocated expenses. Payments made prior to the receipt of goods or services to be used in research and development are capitalized until the related goods are delivered or services performed.
Segment Reporting	Segment Reporting Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company and its chief operating decision-maker view the Company’s operations and manage its business in one operating segment.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding for the period, without consideration for potentially dilutive securities. The Company has excluded weighted-average unvested shares of 1,275,436 shares and 1,230,860 shares, from the weighted-average number of common shares outstanding for the three months ended September 30, 2023 and 2022, respectively, and 1,143,588 shares and 1,440,400 shares, from the weighted-average number of common shares outstanding for the nine months ended September 30, 2023 and 2022, respectively. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common shares and dilutive common stock equivalents outstanding for the period determined using the treasury-stock and if-converted methods. Dilutive common stock equivalents are comprised of convertible preferred stock, unvested common stock subject to repurchase and options outstanding under the Company’s stock option plans. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding as inclusion of the potentially dilutive securities would be anti-dilutive.
401(k) Plan	Employee contributions are voluntary and are determined on an individual basis, limited to the maximum amount allowable under federal tax regulations. The Company, at its discretion, may make certain matching contributions to the 401(k) plan.

Organization and Summary of S_3

Organization and Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following tables summarize the Company’s financial instruments measured at fair value on a recurring basis (in thousands): Fair Value Measurements at Total Quoted Prices in Significant Significant As of September 30, 2023: Assets: Cash equivalents: Money market funds $ 220,045 $ 220,045 $ — $ — Commercial paper 7,478 — 7,478 — U.S. treasury securities 14,856 14,856 — — Total cash equivalents 242,379 234,901 7,478 — Short-term investments: Commercial paper 47,653 — 47,653 — Corporate debt securities 8,042 — 8,042 — U.S. agency securities 25,233 — 25,233 — U.S. treasury securities 207,277 207,277 — — Total short-term investments 288,205 207,277 80,928 — Total assets measured at fair value on a recurring basis $ 530,584 $ 442,178 $ 88,406 $ — As of December 31, 2022: Assets: Cash equivalents: Money market fund $ 9,691 $ 9,691 $ — $ — Commercial paper 106,042 — 106,042 — Corporate debt securities 7,677 — 7,677 — Total cash equivalents 123,410 9,691 113,719 — Short-term investments: Asset backed securities 105 — 105 — Commercial paper 85,732 — 85,732 — Corporate debt securities 16,661 — 16,661 — U.S. agency securities 15,351 — 15,351 — U.S. treasury securities 49,238 49,238 — — Total short-term investments 167,087 49,238 117,849 — Total assets measured at fair value on a recurring basis $ 290,497 $ 58,929 $ 231,568 $ —
Summary of Condensed Cash Flow Statement	Cash, cash equivalents and restricted cash presented in the accompanying condensed statements of cash flows consist of the following (in thousands): September 30, 2023 2022 Cash and cash equivalents $ 251,964 $ 215,585 Restricted cash 339 339 Total $ 252,303 $ 215,924
Summary of Available-for-Sale Securities	The following tables summarize available-for-sale securities (in thousands): As of September 30, 2023 Maturity Amortized Unrealized Estimated Gains Losses Cash equivalents: Money market funds $ 220,045 $ — $ — $ 220,045 Commercial paper 1 year or less 7,477 1 — 7,478 U.S. treasury securities 1 year or less 14,854 2 — 14,856 Total cash equivalents 242,376 3 — 242,379 Short-term investments: Commercial paper 2 years or less 47,701 — (48) 47,653 Corporate debt securities 2 years or less 8,078 1 (37) 8,042 U.S. agency securities 2 years or less 25,323 — (90) 25,233 U.S. treasury securities 2 years or less 207,492 4 (219) 207,277 Total short-term investments 288,594 5 (394) 288,205 Total $ 530,970 $ 8 $ (394) $ 530,584 As of December 31, 2022 Maturity Amortized Unrealized Estimated Gains Losses Cash equivalents: Money market funds $ 9,691 $ — $ — $ 9,691 Commercial paper 1 year or less 106,014 28 — 106,042 Corporate debt securities 1 year or less 7,677 — — 7,677 Total cash equivalents 123,382 28 — 123,410 Short-term investments: Asset backed securities 2 years or less 105 — — 105 Commercial paper 1 year or less 85,746 33 (47) 85,732 Corporate debt securities 2 years or less 16,699 2 (40) 16,661 U.S. agency securities 2 years or less 15,353 10 (12) 15,351 U.S. treasury securities 2 years or less 49,765 — (527) 49,238 Total short-term investments 167,668 45 (626) 167,087 Total $ 291,050 $ 73 $ (626) $ 290,497
Summary of Potentially Dilutive Securities	Potentially dilutive securities not included in the calculation of diluted net loss per share, because to do so would be anti-dilutive, are as follows (in common stock equivalent shares): Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Convertible preferred stock outstanding – 35,543,204 – 35,543,204 Common stock options 4,257,580 2,983,404 4,257,580 2,983,404 Unvested common stock 1,221,005 1,129,250 1,221,005 1,129,250 Total 5,478,585 39,655,858 5,478,585 39,655,858

Balance Sheet Details (Tables)

Balance Sheet Details (Tables)	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule Property and Equipment	Property and equipment, net consist of the following (in thousands): September 30, December 31, Laboratory equipment $ 8,989 $ 7,484 Computer equipment and software 304 185 Furniture and fixtures 522 522 Leasehold improvements 163 163 Construction in progress 43,012 8,603 52,990 16,957 Less accumulated depreciation (3,294) (1,873) Total $ 49,696 $ 15,084
Schedule of Accrued Liabilities	Accrued liabilities consist of the following (in thousands): September 30, December 31, Accrued compensation $ 3,076 $ 2,621 Accrued research and development 3,480 3,209 Accrued property and equipment purchases 6,267 471 Other accrued liabilities 787 390 Total $ 13,610 $ 6,691

Commitments, Contingencies an_2

Commitments, Contingencies and Collaboration and License Agreements (Tables)	9 Months Ended
	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Summary of Operating Leases	Information related to the Company’s operating leases is as follows (in thousands): Three Months Ended Nine Months Ended 2023 2022 2023 2022 Operating lease expense $ 494 $ 495 $ 1,482 $ 1,443 Variable lease expenses $ 305 $ 173 $ 845 $ 502 Cash paid for amounts included in the measurement of lease liabilities $ 501 $ 487 $ 1,503 $ 1,322
Schedule of Future Minimum Noncancelable Operating Lease Payments	The following table presents non-cancelable future minimum lease payments under operating leases (in thousands, except discount rate and remaining term): September 30, Periods ending December 31: 2023 (remaining 3 months) $ 506 2024 2,070 2025 2,132 2026 2,196 2027 2,261 Thereafter 3,414 Total minimum lease payments 12,579 Less: amount representing interest (2,855) Total operating lease liabilities 9,724 Less: current portion of lease liabilities (1,266) Operating lease liabilities, net of current portion $ 8,458 Weighted-average discount rate 8.6 % Weighted-average remaining term 6.0 years

Convertible Preferred Stock a_2

Convertible Preferred Stock and Stockholders’ Equity (Deficit) (Tables)	9 Months Ended
	Sep. 30, 2023
Equity [Abstract]
Summary Of Temporary Equity	The authorized, issued and outstanding shares of convertible preferred stock as of December 31, 2022 consist of the following (in thousands, except share amounts): Shares Shares Issued Liquidation Carrying Series A 45,000,000 8,753,147 $ 41,512 $ 45,937 Series B 46,666,672 9,077,342 96,860 104,270 Series C 23,999,996 4,668,338 99,628 105,702 Series D 63,972,982 12,443,676 159,755 159,349 Total 179,639,650 34,942,503 $ 397,755 $ 415,258
Schedule of Share-Based Payment Award Assumptions	The following table summarizes information about the significant Level 3 unobservable inputs used to estimate the fair value of the Company’s preferred stock at the modification date: Risk-free interest rate 3.45 % Expected volatility 80.0 % Expected term (in years) 2.0 Expected dividend yield 0.0 %
Schedule of Unvested Shares and Stock Liability	A summary of the Company’s unvested shares and unvested stock liability, including unvested Founders Stock, is as follows (in thousands, except share data): Number of Unvested Balance at December 31, 2022 982,299 $ 929 Early exercised shares 745,567 2,413 Vested shares (506,861) (722) Balance at September 30, 2023 1,221,005 $ 2,620
Schedule of Stock Option Activity	A summary of the Company’s stock option activity is as follows (in thousands, except share and per share data): Number of Weighted- Weighted- Aggregate Balance at December 31, 2022 4,674,131 $ 3.07 9.47 $ 21,702 Granted 879,628 $ 6.71 Exercised (1,209,126) $ 3.22 Cancelled (87,053) $ 2.99 Balance at September 30, 2023 4,257,580 $ 3.78 8.97 $ 78,411 Vested and expected to vest at September 30, 2023 4,257,580 $ 3.78 8.97 $ 78,411 Exercisable at September 30, 2023 4,219,723 $ 3.66 8.96 $ 78,251
Schedule of Share-Based Compensation Expense	The assumptions used in the Black-Scholes option pricing model to determine the fair value of stock option grants were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Risk-free interest rate 4.47% – 4.63% —% 3.41% – 4.63% 1.58% – 2.93% Expected volatility 93.8% – 94.7% —% 88.9% – 94.7% 81.9% – 84.5% Expected term (in years) 5.77 – 6.07 0.00 5.77 – 6.07 6.03 – 10.00 Expected dividend yield 0.0% 0.0% 0.0% 0.0%
Schedule of Share-Based Compensation Expense	Stock-based compensation expense has been reported in the condensed statements of operations and comprehensive loss as follows (in thousands): Three Months Ended Nine Months Ended 2023 2022 2023 2022 Research and development $ 1,063 $ 757 $ 3,023 $ 2,219 General and administrative 1,501 690 4,172 2,000 Total $ 2,564 $ 1,447 $ 7,195 $ 4,219
Summary Of Common Stock Reserved For Future Issuance	Common stock reserved for future issuance consists of the following: September 30, December 31, Conversion of preferred stock — 35,543,204 Common stock options outstanding 4,257,580 4,674,131 Shares available for issuance under the Plans 6,006,598 799,173 Shares available for purchase under the ESPP 600,000 — Total 10,864,178 41,016,508

Organization and Summary of S_4

Organization and Summary of Significant Accounting Policies - Narrative (Details) $ / shares in Units, $ in Thousands			3 Months Ended		9 Months Ended
	Sep. 14, 2023 USD ($) $ / shares shares	Sep. 07, 2023	Sep. 30, 2023 USD ($) position shares	Sep. 30, 2022 shares	Sep. 30, 2023 USD ($) position segment shares	Sep. 30, 2022 shares	Dec. 31, 2022 USD ($) position
Description Of Business And Basis Of Presentation [Line Items]
Reverse stock split ratio		0.1945
Accumulated deficit			$ 180,127		$ 180,127		$ 130,116
Cash, cash equivalents and investment securities			540,200		540,200
Interest receivables			$ 700		$ 700		$ 500
Number of companies | position			47		47		29
Fair market value			$ 232,800		$ 232,800		$ 101,600
Unrealized loss position			$ 400		$ 400		$ 600
Number of companies in loss position for greater than 12 months | position			0		0		8
Fair market value with continuous loss position for more than 12 months							$ 34,300
Gross unrealized loss position with continuous loss position for more than 12 months							500
Deferred offering costs			$ 0		$ 0		$ 0
Number of operating segments | segment					1
Weighted-average unvested shares | shares			1,275,436	1,230,860	1,143,588	1,440,400
IPO
Description Of Business And Basis Of Presentation [Line Items]
Sale of stock (in shares) | shares	18,706,240
Offering price (in dollars per share) | $ / shares	$ 18
Proceeds from initial public offering	$ 310,400
Conversion of convertible preferred stock into common stock (in shares) | shares	35,616,773
Over-Allotment Option
Description Of Business And Basis Of Presentation [Line Items]
Sale of stock (in shares) | shares	2,591,640

Organization and Summary of S_5

Organization and Summary of Significant Accounting Policies - Fair Value (Details) - Fair Value, Recurring - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 242,379	$ 123,410
Short-term investments:	288,205	167,087
Total assets measured at fair value on a recurring basis	530,584	290,497
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments:	47,653	85,732
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments:	8,042	16,661
U.S. agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments:	25,233	15,351
U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments:	207,277	49,238
Asset backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments:		105
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	220,045	9,691
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	7,478	106,042
U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	14,856
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		7,677
Quoted Prices in Active Markets For Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	234,901	9,691
Short-term investments:	207,277	49,238
Total assets measured at fair value on a recurring basis	442,178	58,929
Quoted Prices in Active Markets For Identical Assets (Level 1) | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments:	0	0
Quoted Prices in Active Markets For Identical Assets (Level 1) | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments:	0	0
Quoted Prices in Active Markets For Identical Assets (Level 1) | U.S. agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments:	0	0
Quoted Prices in Active Markets For Identical Assets (Level 1) | U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments:	207,277	49,238
Quoted Prices in Active Markets For Identical Assets (Level 1) | Asset backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments:		0
Quoted Prices in Active Markets For Identical Assets (Level 1) | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	220,045	9,691
Quoted Prices in Active Markets For Identical Assets (Level 1) | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Quoted Prices in Active Markets For Identical Assets (Level 1) | U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	14,856
Quoted Prices in Active Markets For Identical Assets (Level 1) | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	7,478	113,719
Short-term investments:	80,928	117,849
Total assets measured at fair value on a recurring basis	88,406	231,568
Significant Other Observable Inputs (Level 2) | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments:	47,653	85,732
Significant Other Observable Inputs (Level 2) | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments:	8,042	16,661
Significant Other Observable Inputs (Level 2) | U.S. agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments:	25,233	15,351
Significant Other Observable Inputs (Level 2) | U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments:	0	0
Significant Other Observable Inputs (Level 2) | Asset backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments:		105
Significant Other Observable Inputs (Level 2) | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Significant Other Observable Inputs (Level 2) | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	7,478	106,042
Significant Other Observable Inputs (Level 2) | U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0
Significant Other Observable Inputs (Level 2) | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		7,677
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Short-term investments:	0	0
Total assets measured at fair value on a recurring basis	0	0
Significant Unobservable Inputs (Level 3) | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments:	0	0
Significant Unobservable Inputs (Level 3) | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments:	0	0
Significant Unobservable Inputs (Level 3) | U.S. agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments:	0	0
Significant Unobservable Inputs (Level 3) | U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments:	0	0
Significant Unobservable Inputs (Level 3) | Asset backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments:		0
Significant Unobservable Inputs (Level 3) | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Significant Unobservable Inputs (Level 3) | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Significant Unobservable Inputs (Level 3) | U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 0
Significant Unobservable Inputs (Level 3) | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		$ 0

Organization and Summary of S_6

Organization and Summary of Significant Accounting Policies - Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Cash and cash equivalents	$ 251,964	$ 129,159	$ 215,585
Restricted cash	339	339	339
Total	$ 252,303	$ 129,498	$ 215,924	$ 50,851

Organization and Summary of S_7

Organization and Summary of Significant Accounting Policies - Available-For-Sale Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	$ 530,970	$ 291,050
Unrealized gains	8	73
Unrealized losses	(394)	(626)
Estimated Fair Value	530,584	290,497
Cash equivalents:
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	242,376	123,382
Unrealized gains	3	28
Unrealized losses	0	0
Estimated Fair Value	242,379	123,410
Cash equivalents: | Money market funds
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	220,045	9,691
Unrealized gains	0	0
Unrealized losses	0	0
Estimated Fair Value	220,045	9,691
Cash equivalents: | Commercial paper
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	7,477	106,014
Unrealized gains	1	28
Unrealized losses	0	0
Estimated Fair Value	7,478	106,042
Cash equivalents: | U.S. treasury securities
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	14,854
Unrealized gains	2
Unrealized losses	0
Estimated Fair Value	14,856
Cash equivalents: | Corporate debt securities
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost		7,677
Unrealized gains		0
Unrealized losses		0
Estimated Fair Value		7,677
Short-term investments:
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	288,594	167,668
Unrealized gains	5	45
Unrealized losses	(394)	(626)
Estimated Fair Value	288,205	167,087
Short-term investments: | Commercial paper
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	47,701	85,746
Unrealized gains	0	33
Unrealized losses	(48)	(47)
Estimated Fair Value	47,653	85,732
Short-term investments: | U.S. treasury securities
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	207,492	49,765
Unrealized gains	4	0
Unrealized losses	(219)	(527)
Estimated Fair Value	207,277	49,238
Short-term investments: | Corporate debt securities
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	8,078	16,699
Unrealized gains	1	2
Unrealized losses	(37)	(40)
Estimated Fair Value	8,042	16,661
Short-term investments: | U.S. agency securities
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	25,323	15,353
Unrealized gains	0	10
Unrealized losses	(90)	(12)
Estimated Fair Value	$ 25,233	15,351
Short-term investments: | Asset backed securities
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost		105
Unrealized gains		0
Unrealized losses		0
Estimated Fair Value		$ 105

Organization and Summary of S_8

Organization and Summary of Significant Accounting Policies - Potentially Dilutive Securities (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities (in shares)	5,478,585	39,655,858	5,478,585	39,655,858
Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities (in shares)	0	35,543,204	0	35,543,204
Common stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities (in shares)	4,257,580	2,983,404	4,257,580	2,983,404
Unvested common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities (in shares)	1,221,005	1,129,250	1,221,005	1,129,250

Balance Sheet Details - Propert

Balance Sheet Details - Property And Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Offsetting Liabilities [Line Items]
Total property and equipment, gross	$ 52,990	$ 16,957
Less accumulated depreciation	(3,294)	(1,873)
Total	49,696	15,084
Laboratory equipment
Offsetting Liabilities [Line Items]
Total property and equipment, gross	8,989	7,484
Computer equipment and software
Offsetting Liabilities [Line Items]
Total property and equipment, gross	304	185
Furniture and fixtures
Offsetting Liabilities [Line Items]
Total property and equipment, gross	522	522
Leasehold improvements
Offsetting Liabilities [Line Items]
Total property and equipment, gross	163	163
Construction in progress
Offsetting Liabilities [Line Items]
Total property and equipment, gross	$ 43,012	$ 8,603

Balance Sheet Details - Narrati

Balance Sheet Details - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Depreciation	$ 0.5	$ 0.4	$ 1.4	$ 1.1

Balance Sheet Details - Accrued

Balance Sheet Details - Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued compensation	$ 3,076	$ 2,621
Accrued research and development	3,480	3,209
Accrued property and equipment purchases	6,267	471
Other accrued liabilities	787	390
Accrued liabilities	$ 13,610	$ 6,691

Commitments, Contingencies an_3

Commitments, Contingencies and Collaboration and License Agreements - Narrative (Details) $ in Thousands

3 Months Ended

9 Months Ended

12 Months Ended

Sep. 30, 2023 USD ($)

Sep. 30, 2022 USD ($)

Sep. 30, 2023 USD ($)

Sep. 30, 2022 USD ($)

Dec. 31, 2022 USD ($) shares

Dec. 31, 2021 shares

Dec. 31, 2020 shares

Aug. 09, 2022

Mar. 31, 2022 USD ($)

Nov. 30, 2021 USD ($) ft²

May 31, 2021 USD ($)

Feb. 28, 2021 USD ($)

Aug. 31, 2020

Aug. 03, 2020 USD ($)

Other Commitments [Line Items]

Area of industrial space | ft²

63,000

Right-of-use assets

$ 8,484

$ 8,484

$ 9,308

Operating lease liability

9,724

9,724

Research and development

18,170

$ 18,828

48,759

$ 46,416

Peptidream, Inc. | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement

Other Commitments [Line Items]

Research term

4 years

2 years

Research term extension

1 year

Warrant or right issuable as a percentage of fully diluted equity

5%

Amounts incurred or paid

0

Term of agreement

10 years

Right to terminate term

60 days

Issuance of common stock for license rights (in shares) | shares

851,943

286,656

1,187,980

Research and development

6,500

6,500

Peptidream, Inc. | Specified Development Regulatory Milestone Member | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement

Other Commitments [Line Items]

Asset acquisition milestone amount

$ 380,000

Nimble Therapeutics, Inc. | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement

Other Commitments [Line Items]

Right to terminate term

90 days

Research and development

0

100

200

300

Upfront payment

$ 800

Unamortized balance

0

0

Nimble Therapeutics, Inc. | Discovery, Development and Sales Milestone | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement

Other Commitments [Line Items]

Aggregate payments

201,700

Nimble Therapeutics, Inc. | Discovery, Development and First Comercial Sales Milestone | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement

Other Commitments [Line Items]

Aggregate payments

$ 897,500

Ablaze Pharmaceuticals | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement

Other Commitments [Line Items]

Right to terminate term

60 days

Upfront payment

$ 0

Maximum payments, per product

$ 70,000

Niowave, Inc | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement

Other Commitments [Line Items]

Research term

20 years

Asset acquisition milestone amount

$ 10,000

Right to terminate term

6 months

Research and development

0

0

0

1,700

Unamortized balance

0

0

$ 0

Milestone payments

0

$ 0

0

$ 1,500

Milestones payable

0

0

$ 5,500

Office And Laboratory

Other Commitments [Line Items]

Lease term

5 years

Office And Laboratory | Standby Letters of Credit

Other Commitments [Line Items]

Maximum borrowing capacity

$ 100

$ 100

Land

Other Commitments [Line Items]

Lease term

5 years

Right-of-use assets

$ 2,300

Operating lease liability

$ 2,400

Land | Letter of Credit

Other Commitments [Line Items]

Maximum borrowing capacity

$ 200

Commitments, Contingencies an_4

Commitments, Contingencies and Collaboration and License Agreements - Operating Lease (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Commitments and Contingencies Disclosure [Abstract]
Operating lease expense	$ 494	$ 495	$ 1,482	$ 1,443
Variable lease expenses	305	173	845	502
Cash paid for amounts included in the measurement of lease liabilities	$ 501	$ 487	$ 1,503	$ 1,322

Commitments, Contingencies an_5

Commitments, Contingencies and Collaboration and License Agreements - Operating Lease Payments (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
2023 (remaining 3 months)	$ 506
2024	2,070
2025	2,132
2026	2,196
2027	2,261
Thereafter	3,414
Total minimum lease payments	12,579
Less: amount representing interest	(2,855)
Total operating lease liabilities	9,724
Less: current portion of lease liabilities	(1,266)	$ (1,144)
Operating lease liabilities, net of current portion	$ 8,458	$ 9,425
Weighted-average discount rate	8.60%
Weighted-average remaining term	6 years

Convertible Preferred Stock a_3

Convertible Preferred Stock and Stockholders’ Equity (Deficit) - Narrative (Details) - USD ($)		1 Months Ended	2 Months Ended	3 Months Ended		4 Months Ended	9 Months Ended
	Sep. 14, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Jul. 31, 2020	Sep. 30, 2023	Sep. 30, 2022	Jan. 01, 2024	Dec. 31, 2022	Feb. 28, 2022
Class of Stock [Line Items]
Preferred stock, shares outstanding (in shares)		0		0			0			0
Preferred stock, shares issued (in shares)		0		0			0			0
Issuance of convertible preferred stock (in shares)					12,443,676			12,443,676
Proceeds from stock issued					$ 159,349,000			$ 159,349,000
Deemed dividend upon down round of convertible preferred stock		$ 1,200,000
Common stock, par value (in dollars per share)		$ 0.0001		$ 0.0001			$ 0.0001			$ 0.0001
Vested shares (in shares)							506,861
Unvested stock (in shares)		1,221,005		1,221,005			1,221,005			982,299
Shares available for issuance under the 2023 Plan (in shares)											194,514
Stock repurchase price (in dollars per share)											$ 9.56226
Common stock reserved for future issuance (in shares)		10,864,178		10,864,178			10,864,178			41,016,508
Compensation expense				$ 2,564,000	$ 1,447,000		$ 7,195,000	$ 4,219,000
Weighted average grant date fair value (in dollars per share)				$ 8.86	$ 0		$ 8.36	$ 7.11
Unrecognized stock based compensation		$ 26,100,000		$ 26,100,000			$ 26,100,000
Weighted-average period (in years)							2 years 8 months 12 days
Options vested and expected to vest, aggregate intrinsic value				$ 1,900,000	$ 0		$ 9,800,000	$ 400,000
Employee Stock Purchase Plan
Class of Stock [Line Items]
Increase in number of common stock (percent)		1%		1%			1%
Common stock reserved for future issuance (in shares)		600,000		600,000			600,000			0
Compensation expense				$ 0			$ 0
Stock-based compensation expense witheld				$ 0			$ 0
2023 Plan
Class of Stock [Line Items]
Common stock, shares approved (in shares)		6,000,000		6,000,000			6,000,000
Increase in number of common stock (percent)		5%		5%			5%
IPO
Class of Stock [Line Items]
Conversion of convertible preferred stock into common stock (in shares)	35,616,773
Offering price (in dollars per share)	$ 18
Forecast | Employee Stock Purchase Plan
Class of Stock [Line Items]
Increase in shares (in shares)									1,200,000
Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares outstanding (in shares)		0		0			0
Preferred stock, shares issued (in shares)		0		0			0
Series D
Class of Stock [Line Items]
Issuance of convertible preferred stock (in shares)			12,443,676
Offering price (in dollars per share)			$ 12.83824		$ 12.83824			$ 12.83824
Proceeds from stock issued			$ 159,800,000
Series C
Class of Stock [Line Items]
Deemed dividend upon down round of convertible preferred stock			$ 4,600,000
Founders Stock
Class of Stock [Line Items]
Issuance of common stock (in shares)						1,884,213
Common stock, par value (in dollars per share)						$ 0.005141
Vested shares (in shares)						1,167,087
Stock fully vested (in shares)						717,126
Research term						4 years
Unvested stock (in shares)		178,761		178,761			178,761			313,230
Repurchase liability		$ 1,000		$ 1,000			$ 1,000			$ 2,000

Convertible Preferred Stock a_4

Convertible Preferred Stock and Stockholders’ Equity (Deficit) - Convertible Preferred Stock (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Class of Stock [Line Items]
Convertible preferred stock, shares authorized (in shares)	0		179,639,650
Convertible preferred stock, shares outstanding (in shares)	0	34,942,503	34,942,503	34,942,503	22,498,827	22,498,827
Convertible preferred stock, shares issued (in shares)	0		34,942,503
Convertible preferred stock, liquidation preference	$ 0		$ 397,755
Convertible preferred stock, carrying value	$ 0	$ 415,258	$ 415,258	$ 415,258	$ 255,909	$ 255,909
Series A
Class of Stock [Line Items]
Convertible preferred stock, shares authorized (in shares)			45,000,000
Convertible preferred stock, shares outstanding (in shares)			8,753,147
Convertible preferred stock, shares issued (in shares)			8,753,147
Convertible preferred stock, liquidation preference			$ 41,512
Convertible preferred stock, carrying value			$ 45,937
Series B
Class of Stock [Line Items]
Convertible preferred stock, shares authorized (in shares)			46,666,672
Convertible preferred stock, shares outstanding (in shares)			9,077,342
Convertible preferred stock, shares issued (in shares)			9,077,342
Convertible preferred stock, liquidation preference			$ 96,860
Convertible preferred stock, carrying value			$ 104,270
Series C
Class of Stock [Line Items]
Convertible preferred stock, shares authorized (in shares)			23,999,996
Convertible preferred stock, shares outstanding (in shares)			4,668,338
Convertible preferred stock, shares issued (in shares)			4,668,338
Convertible preferred stock, liquidation preference			$ 99,628
Convertible preferred stock, carrying value			$ 105,702
Series D
Class of Stock [Line Items]
Convertible preferred stock, shares authorized (in shares)			63,972,982
Convertible preferred stock, shares outstanding (in shares)			12,443,676
Convertible preferred stock, shares issued (in shares)			12,443,676
Convertible preferred stock, liquidation preference			$ 159,755
Convertible preferred stock, carrying value			$ 159,349

Convertible Preferred Stock a_5

Convertible Preferred Stock and Stockholders’ Equity (Deficit) - Unvested (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($) shares
Number of Unvested Shares
Beginning balance (in shares) | shares	982,299
Early exercised shares (in shares) | shares	745,567
Vested shares (in shares) | shares	(506,861)
Ending balance (in shares) | shares	1,221,005
Unvested Stock Liability
Beginning balance | $	$ 929
Early exercised shares | $	2,413
Vested shares | $	(722)
Ending balance | $	$ 2,620

Convertible Preferred Stock a_6

Convertible Preferred Stock and Stockholders’ Equity (Deficit) - Stock Option Activity (Details) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares
Number of Outstanding Options
Beginning balance (in shares) | shares	4,674,131
Granted (in shares) | shares	879,628
Exercised (in shares) | shares	(1,209,126)
Cancelled (in shares) | shares	(87,053)
Ending balance (in shares) | shares	4,257,580	4,674,131
Options vested and expected to vest, number of options (in shares) | shares	4,257,580
Options exercisable, number of options (in shares) | shares	4,219,723
Weighted- Average Exercise Price
Options outstanding beginning balance, weighted average exercise price per share (in dollars per share) | $ / shares	$ 3.07
Options granted beginning balance, weighted average exercise price per share (in dollars per share) | $ / shares	6.71
Options exercised beginning balance, weighted average exercise price per share (in dollars per share) | $ / shares	3.22
Options cancelled beginning balance, weighted average exercise price per share (in dollars per share) | $ / shares	2.99
Options outstanding ending balance, weighted average exercise price per share (in dollars per share) | $ / shares	3.78	$ 3.07
Options vested and expected to vest, weighted average exercise price per share (in dollars per share) | $ / shares	3.78
Options exercisable, weighted average exercise price per share (in dollars per share) | $ / shares	$ 3.66
Weighted- Average Remaining Contractual Term (in Years)
Options outstanding, weighted average remaining contractual term	8 years 11 months 19 days	9 years 5 months 19 days
Options vested and expected to vest, weighted average remaining contractual term (in years)	8 years 11 months 19 days
Options exercisable, weighted average remaining contractual term (in years)	8 years 11 months 15 days
Aggregate Intrinsic Value [Abstract]
Options outstanding, aggregate intrinsic value | $	$ 78,411	$ 21,702
Options vested and expected to vest, aggregate intrinsic value | $	78,411
Options exercisable, aggregate intrinsic value | $	$ 78,251

Convertible Preferred Stock a_7

Convertible Preferred Stock and Stockholders’ Equity (Deficit) - Significant Assumptions Fair Value (Details) - Convertible Preferred Stock		3 Months Ended		9 Months Ended
	Dec. 01, 2022	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Class of Stock [Line Items]
Risk-free interest rate, minimum		4.47%		3.41%	1.58%
Risk-free interest rate, maximum		4.63%		4.63%	2.93%
Risk-free interest rate	3.45%		0%
Expected volatility, minimum		93.80%		88.90%	81.90%
Expected volatility, maximum		94.70%		94.70%	84.50%
Expected volatility	80%		0%
Expected term (in years)	2 years		0 years
Expected dividend yield	0%	0%	0%	0%	0%
Minimum
Class of Stock [Line Items]
Expected term (in years)		5 years 9 months 7 days		5 years 9 months 7 days	6 years 10 days
Maximum
Class of Stock [Line Items]
Expected term (in years)		6 years 25 days		6 years 25 days	10 years

Convertible Preferred Stock a_8

Convertible Preferred Stock and Stockholders’ Equity (Deficit) - Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Class of Stock [Line Items]
Compensation expense	$ 2,564	$ 1,447	$ 7,195	$ 4,219
Research and development
Class of Stock [Line Items]
Compensation expense	1,063	757	3,023	2,219
General and administrative
Class of Stock [Line Items]
Compensation expense	$ 1,501	$ 690	$ 4,172	$ 2,000

Convertible Preferred Stock a_9

Convertible Preferred Stock and Stockholders’ Equity (Deficit) - Common Stock Reserved (Details) - shares	Sep. 30, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	10,864,178	41,016,508
Conversion of preferred stock
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	0	35,543,204
Common stock options outstanding
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	4,257,580	4,674,131
Shares available for issuance under the Plans
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	6,006,598	799,173
Shares available for purchase under the ESPP
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	600,000	0