Rain Oncology 10-K 9 Mar 23 2022 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2022	Feb. 28, 2023	Jun. 30, 2022
Document and Entity Information
Document Type	10-K
Amendment Flag	false
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Entity File Number	001-40356
Entity Registrant Name	Rain Oncology Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	82-1130967
Entity Address, Address Line One	8000 Jarvis Avenue
Entity Address, Address Line Two	Suite 204
Entity Address, City or Town	Newark
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94560
City Area Code	510
Local Phone Number	953-5559
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	RAIN
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		36,356,233
Entity Public Float			$ 43,929,838
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0001724979
ICFR Auditor Attestation Flag	false
Auditor Name	Ernst & Young LLP
Auditor Location	San Diego, California
Auditor Firm ID	42
Documents Incorporated by Reference	Portions of the Registrant’s definitive proxy statement relating to its 2023 Annual Meeting of Stockholders to be filed with the Securities and Exchange Commission within 120 days after the end of the fiscal year ended December 31, 2022 are incorporated herein by reference in Part III of this Annual Report on Form 10-K where indicated .

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 61,955	$ 24,780
Short-term investments	68,499	115,438
Prepaid and other current assets	3,174	5,928
Total current assets	133,628	146,146
Property and equipment, net	93	165
Operating lease right-of-use asset	258	386
Other assets	1,201	443
Total assets	135,180	147,140
Current liabilities:
Accounts payable	7,146	6,112
Accrued research and development	8,232	4,349
Other accrued liabilities	6,424	5,694
Operating lease liability, current portion	164	160
Total current liabilities	21,966	16,315
Operating lease liability, net of current portion	113	252
Other long-term liabilities	65	69
Total liabilities	22,144	16,636
Commitments and contingencies
Stockholders' equity:
Common stock, $0.001 par value; 250,000,000 shares authorized as of December 31, 2022 and December 31, 2021, respectively; 36,290,292 shares (comprised of 25,947,572 shares of common stock and 10,342,720 shares of non-voting common stock) and 26,475,812 shares (comprised of 18,748,342 shares of common stock and 7,727,470 shares of non-voting common stock) issued and outstanding as of December 31, 2022 and December 31, 2021, respectively	37	27
Additional paid-in capital	278,853	220,530
Accumulated other comprehensive loss	(166)	(89)
Accumulated deficit	(165,688)	(89,964)
Total stockholders' equity	113,036	130,504
Total liabilities and stockholders' equity	$ 135,180	$ 147,140

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2022	Dec. 31, 2021
Preferred stock, par value	$ 0.001	$ 0.001
Preferred Stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, Par value	$ 0.001	$ 0.001
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	36,290,292	26,475,812
Common stock, shares outstanding	36,290,292	26,475,812
Common Stock
Common stock, shares issued	25,947,572	18,748,342
Non-voting Common Stock
Common stock, shares issued	10,342,720	7,727,470

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Operating expenses:
Research and development	$ 61,400	$ 40,773
General and administrative	15,736	10,739
Total operating expenses	77,136	51,512
Loss from operations	(77,136)	(51,512)
Other income:
Interest and other income	1,415	120
Total other income	1,415	120
Net loss before income tax expense	(75,721)	(51,392)
Income tax expense	(3)	(2)
Net loss	$ (75,724)	$ (51,394)
Net loss per share, basic	$ (2.71)	$ (2.65)
Net loss per share, diluted	$ (2.71)	$ (2.65)
Weighted-average shares used to compute net loss per share, basic	27,985,446	19,405,833
Weighted-average shares used to compute net loss per share, diluted	27,985,446	19,405,833
Net loss	$ (75,724)	$ (51,394)
Other comprehensive loss:
Unrealized loss on short-term investments	(77)	(89)
Comprehensive loss	$ (75,801)	$ (51,483)

Consolidated Statements of Conv

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Common Stock November 2022 Offering	Common Stock	Additional Paid-in Capital November 2022 Offering	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss	Series A Convertible Preferred Stock	Series B Convertible Preferred Stock	November 2022 Offering	Total
Balance at Dec. 31, 2020		$ 4		$ 1,149	$ (38,570)					$ (37,417)
Balance, Shares at Dec. 31, 2020		3,530,975
Temporary equity, balance at Dec. 31, 2020							$ 20,147	$ 74,550
Temporary equity, balance, Shares at Dec. 31, 2020							3,731,208	12,542,198
Temporary equity conversion of convertible preferred stock to common stock							$ (20,147)	$ (74,550)
Temporary equity conversion of convertible preferred stock to common stock, shares							(3,731,208)	(12,542,198)
Conversion of convertible preferred stock to common stock		$ 15		94,682						94,697
Conversion of convertible preferred stock to common stock, shares		15,069,330
Issuance of common stock, net of issuance cost		$ 8		121,486						121,494
Issuance of common stock, net of issuance cost, shares		7,845,011
Exercise of stock options				121						121
Exercise of stock options, shares		30,496
Stock-based compensation expense				3,092						3,092
Unrealized loss on investments						$ (89)				(89)
Net loss					(51,394)					(51,394)
Balance at Dec. 31, 2021		$ 27		220,530	(89,964)	(89)				$ 130,504
Balance, Shares at Dec. 31, 2021		26,475,812
Temporary equity, balance, Shares at Dec. 31, 2021										0
Issuance of common stock, net of issuance cost	$ 10		$ 52,859						$ 52,869
Issuance of common stock, net of issuance cost, shares	9,716,398
Exercise of stock options				169						$ 169
Exercise of stock options, shares		40,220
Issuance of common stock from employee stock purchase plan				440						440
Issuance of common stock from employee stock purchase plan, shares		57,862
Stock-based compensation expense				4,855						4,855
Unrealized loss on investments						(77)				(77)
Net loss					(75,724)					(75,724)
Balance at Dec. 31, 2022		$ 37		$ 278,853	$ (165,688)	$ (166)				$ 113,036
Balance, Shares at Dec. 31, 2022		36,290,292
Temporary equity, balance at Dec. 31, 2022							$ 0	$ 0
Temporary equity, balance, Shares at Dec. 31, 2022							0	0		0

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Operating activities
Net loss	$ (75,724)	$ (51,394)
Adjustments to reconcile net loss to cash used in operating activities:
In-process research and development expense (reduction)	(1,000)	5,500
Depreciation and amortization expense	80	71
Stock-based compensation expense	4,855	3,092
Amortization of premium and accretion of discounts on short-term investments, net	(331)	81
Fair value loss on investments	(9)	(1)
Changes in operating assets and liabilities:
Prepaid and other current assets	2,754	(5,266)
Operating lease right-of-use asset and liability, net	(7)	19
Other assets	(460)	181
Accounts payable	1,034	5,288
Accrued research and development	3,883	2,822
Other accrued liabilities	1,726	2,144
Net cash used in operating activities	(63,199)	(37,463)
Investing activities
Purchases of short-term investments	(76,198)	(163,557)
Purchases of property and equipment	(8)	(128)
Payment of in-process research and development expense		(2,500)
Maturities of short-term investments	123,400	47,950
Net cash provided by (used in) investing activities	47,194	(118,235)
Financing Activities
Proceeds from initial public offering		133,366
Proceeds from the issuance of common stock under the Company's equity incentive plans and employee stock purchase plan	609	121
Proceeds from issuance of common stock in connection with the November 2022 Offering	56,647
Net cash provided by financing activities	53,180	121,615
Net increase (decrease) in cash and cash equivalents	37,175	(34,083)
Cash and cash equivalents at beginning of period	24,780	58,863
Cash and cash equivalents at end of period	61,955	24,780
Supplemental schedule of non-cash investing and financing activities:
Conversion of convertible preferred stock to common stock		94,697
Non-cash in-process research and development accrual (reduction)	(1,000)	3,000
Non-cash additions to property and equipment		9
IPO
Financing Activities
Payments of issuance costs		$ (11,872)
November 2022 Offering
Financing Activities
Payments of issuance costs	(3,778)
ATM Facility
Financing Activities
Payments of issuance costs	$ (298)

Organization and Nature of Oper

Organization and Nature of Operations	12 Months Ended
	Dec. 31, 2022
Organization and Nature of Operations
Organization and Nature of Operations	​ Note 1 – Organization and Nature of Operations Description of Business Rain Oncology Inc. (“Rain” or the “Company”), formerly known as Rain Therapeutics Inc., was incorporated in the state of Delaware in April 2017 On June 22, 2022, the Company formed Rain Oncology Australia Pty Ltd (“Rain Oncology Australia”), a wholly owned subsidiary incorporated under the laws of Australia. As of December 31, 2022, Rain Oncology Australia was not yet operational. On December 22, 2022, the Company filed a Certificate of Amendment to its Amended and Restated Certificate of Incorporation with the Secretary of State of the State of Delaware to effect a change of the Company’s name from “Rain Therapeutics Inc.” to “Rain Oncology Inc.” effective as of December 30, 2022. Initial Public Offering On April 27, 2021, the Company completed its initial public offering (“IPO”) in which the Company issued and sold 7,352,941 shares of common stock at a public offering price of $17.00 per share. On May 11, 2021, the Company issued an additional 492,070 shares of common stock in connection with the exercise of the underwriters’ option to purchase additional shares at the public offering price. The Company’s net proceeds from the sale of shares in the IPO, including the sale of shares pursuant to the exercise of the underwriters’ option to purchase additional shares, was $121.5 million, net of Immediately prior to the closing of the IPO, 8,344,905 shares of the Company’s convertible preferred stock were exchanged for 7,727,470 shares of non-voting common stock. Upon the closing of the IPO, 7,928,501 shares of the Company’s convertible preferred stock were automatically converted into 7,341,860 shares of common stock. As of December 31, 2022 and 2021 November 2022 Offering In November 2022, the Company entered into an underwriting agreement with Guggenheim Securities, LLC, as the representative of the underwriters named therein (the “Underwriters”) relating to the offering, issuance and sale (the “November 2022 Offering”) of an aggregate of 8,576,330 shares of common stock and non-voting common stock at an offering price per share of $5.83. On November 15, 2022, the Company issued an additional 1,140,068 shares of common stock in connection with the exercise of the Underwriters’ option to purchase additional shares at the offering price. The Company’s net proceeds from the sale of shares in the November 2022 Offering, including the sale of shares pursuant to the exercise of the Underwriters’ option to purchase additional shares, was approximately $52.9 million, net of underwriting discounts and commissions, and other offering fees. Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”). These consolidated financial statements include the accounts of the Company and Rain Oncology Australia Liquidity and Capital Resources The Company has devoted substantially all of its efforts to drug discovery and development, raising capital and building operations. The Company has a limited operating history and has not generated any revenue since its inception, and the sales and income potential of the Company’s business is unproven. The Company has incurred net losses and negative cash flows from operating activities since its inception and expects to continue to incur net losses into the foreseeable future as it continues the development of its product candidates. From inception through December 31, 2022, the Company has funded its operations through net proceeds from its IPO in April 2021 and the November 2022 Offering, and the issuance of convertible promissory notes and convertible preferred stock. The accompanying consolidated financial statements have been prepared assuming the Company will continue as a going concern. Management believes that the Company’s current cash, cash equivalents and short-term investments

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2022
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	Note 2 – Summary of Significant Accounting Policies Use of Estimates The preparation of the Company’s consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that impact the reported amounts of assets, liabilities and expenses and the disclosure of contingent liabilities in the Company’s consolidated financial statements and accompanying notes. The most significant estimate in the Company’s consolidated financial statements relates to the clinical trial expense accruals. Management evaluates its estimates on an ongoing basis. Although these estimates are based on the Company’s historical experience, knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions. Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents. Cash equivalents include commercial paper and money market funds. Available-for-Sale Investments The Company holds investment grade securities consisting of commercial paper, corporate debt securities, U.S. government securities and U.S. agency bonds, classified as available-for-sale (AFS) securities at the time of purchase, since it is the Company’s intent that these investments be available for current operations. The Company has classified all of its AFS securities as current assets on the consolidated balance sheets even though the stated maturity date may be one year or more beyond the current consolidated balance sheet date, which reflects management’s intention to use the proceeds from sales of these securities to fund its operations, as necessary. The Company carries these securities at fair value and reports unrealized gains and losses, if any, as a separate component of accumulated other comprehensive loss. The cost of debt securities is adjusted for amortization of purchase premiums and accretion of discounts to maturity. Such amortization and accretion are included in interest income (expense) in the consolidated statements of operations and comprehensive loss. Realized gains and losses on sales of securities are determined using the specific identification method and recorded in other income (expense), net in the consolidated statement of operations and comprehensive loss. Investments are considered to be impaired when a decline in fair value is judged to be other-than-temporary. The Company consults with its investment managers and considers available quantitative and qualitative evidence in evaluating potential impairment of its investments on a quarterly basis. If the cost of an individual investment exceeds its fair value, the Company evaluates among other factors, general market conditions, the duration and extent to which the fair value is less than cost, and the Company’s intent and ability to hold the investment. Once an impairment is determined to be other-than-temporary, an impairment charge is recorded and a new cost basis in the investment is established. Declines in the value of AFS securities determined to be other than temporary are included in other income (expense), net. Fair Value of Financial Instruments The carrying amounts of all cash equivalents, prepaid expenses and other assets, accounts payable and accrued and other current liabilities are reasonable estimates of their fair value because of the short-term nature of these items. Concentration of Credit Risk Financial instruments, which potentially subject the Company to significant concentration of credit risk, consist primarily of cash, cash equivalents and short-term investments. The Company maintains cash and money market deposits in a federally insured major financial institution in excess of federally insured limits. The Company has not experienced any losses in such accounts and management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institution in which those deposits are held. Research and Development Costs Research and development costs primarily consist of costs associated with the Company’s research and development activities, including its drug discovery efforts, and the preclinical and clinical development of its product candidates. Research and development costs are expensed as incurred. Property and Equipment Property and equipment, net consists of computer equipment, furniture and equipment and leasehold improvements. Leasehold improvements are amortized over the shorter of the estimated useful life or the remainder of the lease term. Computer equipment and furniture and equipment are recorded at cost and depreciated using the straight-line method over the estimated useful lives of the assets (generally two Long-Lived Assets The Company regularly reviews the carrying value and estimated lives of all of its long-lived assets, including property and equipment, to determine whether indicators of impairment may exist which warrant adjustments to carrying values or estimated useful lives. Should an impairment exist, the impairment loss would be measured based on the excess over the carrying amount of the asset’s fair value. The Company has not recognized any impairment losses from inception through December 31, 2022. Commitments The Company recognizes a liability with regard to loss contingencies when it believes it is probable that a liability has occurred, and the amount can be reasonably estimated. If some amount within a range of loss appears at the time to be a better estimate than any other amount within the range, the Company accrues that amount. When no amount within the range is a better estimate than any other amount, the Company accrues the minimum amount in the range. The Company has not recorded any such liabilities as of December 31, 2022. Leases At the inception of a contractual arrangement, the Company determines whether the contract contains a lease by assessing whether there is an identified asset and whether the contract conveys the right to control the use of the identified asset in exchange for consideration over a period of time. If both criteria are met, the Company records the associated lease liability and corresponding right-of-use asset upon commencement of the lease using the implicit rate or a discount rate based on a credit- adjusted secured borrowing rate commensurate with the term of the lease. The Company additionally evaluates leases at their inception to determine if they are to be accounted for as an operating lease or a finance lease. Operating lease assets represent a right to use an underlying asset for the lease term and operating lease liabilities represent an obligation to make lease payments arising from the lease. Operating lease liabilities with a term greater than one year and their corresponding right-of-use assets are recognized on the consolidated balance sheet at the commencement date of the lease based on the present value of lease payments over the expected lease term. Certain adjustments to the right-of-use asset may be required for items such as initial direct costs paid or incentives received. As the Company’s leases do not typically provide an implicit rate, the Company utilizes the appropriate incremental borrowing rate, determined as the rate of interest that the Company would have to pay to borrow on a collateralized basis over a similar term and in a similar economic environment. Lease cost is recognized on a straight-line basis over the lease term and variable lease payments are recognized as operating expenses in the period in which the obligation for those payments is incurred. Variable lease payments primarily include common area maintenance, utilities, real estate taxes, insurance and other operating costs that are passed on from the lessor in proportion to the space leased by the Company. The Company has elected the practical expedient to not separate lease and non-lease components. Preclinical Studies and Clinical Trial Accruals The Company is required to estimate its expenses resulting from its obligations under contracts with vendors, consultants, clinical research organizations and clinical site agreements in connection with conducting preclinical activities and clinical trials. The financial terms of these contracts are subject to negotiations which vary from contract to contract and may result in payment flows that do not match the periods over which materials or services are provided under such contracts. The Company reflects preclinical study and clinical trial expenses in its consolidated financial statements by matching those expenses with the period in which services and efforts are expended. The Company accounts for these expenses according to the progress of the preclinical study or clinical trial as measured by the timing of various aspects of the preclinical study, clinical trial or related activities. The Company determines accrual and prepaid estimates through review of the underlying contracts along with preparation of financial models taking into account correspondence with clinical and other key personnel and third- party service providers as to the progress of preclinical studies, clinical trials or other services being conducted. During the course of a preclinical study or clinical trial, the Company adjusts its expense recognition if actual results differ from its estimates. To date, the Company has not experienced any material differences between accrued costs and actual costs incurred. In-Process Research and Development The Company evaluates whether acquired intangible assets are a business under applicable accounting standards. Additionally, the Company evaluates whether the acquired assets have a future alternative use. Intangible assets that do not have future alternative use, such as the license the Company acquired from Daiichi Sankyo Company, Limited, (Daiichi Sankyo), are considered acquired in-process research and development. When the acquired in-process research and development assets are not part of a business combination, the value of the consideration paid is expensed on the acquisition date. Future costs to develop these assets are recorded to research and development expenses as they are incurred. Patent Costs Costs related to filing and pursuing patent applications are recorded as general and administrative expense and expensed as incurred since recoverability of such expenditures is uncertain. General and Administrative Expenses General and administrative expenses consist of salaries, stock-based compensation, facilities and third-party expenses. General and administrative expenses are associated with the activities of the executive, finance, accounting, information technology, legal and human resource functions. Stock-Based Compensation Stock-based compensation expense represents the grant date fair value of equity awards recognized over the requisite service period of the awards (generally the vesting period) on a straight-line basis. The Company recognizes forfeitures as they occur. The Company estimates the fair value of stock option grants using the Black-Scholes option pricing model. The fair value of restricted stock units (“RSUs”) granted is based on the Company’s closing stock price on the date of grant. Prior to the IPO, the exercise price for all stock options granted was at the estimated fair value of the underlying common stock as determined on the date of grant by the Board of Directors. Income Taxes The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the consolidated financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date. The Company recognizes deferred tax assets to the extent that the Company believes these assets are more likely than not to be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies and results of recent operations. If management determines that the Company would be able to realize its deferred tax assets in the future in excess of their recorded amount, management would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. The Company records uncertain tax positions on the basis of a two-step process whereby (1) management determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more likely than not recognition threshold, management recognizes the largest amount of tax benefit that is more than 50 percent likely to be realized upon ultimate settlement with the related tax authority. The Company recognizes interest and penalties related to unrecognized tax benefits within income tax expense. Any accrued interest and penalties are included within the related tax liability. Effective January 1, 2022, we adopted ASU 2019-12 - Simplifying the Accounting for Income Taxes. The adoption of this standard did not impact the Company’s consolidated financial statements or related disclosures. Comprehensive Loss Comprehensive loss is defined as a change in equity during a period from transactions and other events and circumstances from non-owner sources. The Company’s comprehensive loss includes unrealized gains and losses from short-term investments. Net Loss Per Share Basic net loss per share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding for the period, without consideration of potential dilutive securities. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the sum of the weighted-average number of shares of common stock plus the potential dilutive effects of potential dilutive securities outstanding during the period. Potential dilutive securities are excluded from diluted earnings or loss per share if the effect of such inclusion is antidilutive. The Company’s potentially dilutive securities, which include shares from the 2021 Employee Stock Purchase Plan (the “ESPP”) and outstanding stock options and RSUs under the Company’s equity incentive plan, have been excluded from the computation of diluted net loss per share as they would be anti-dilutive to the net loss per share. For the periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to the Company’s net loss position. Recent Accounting Pronouncements There were no significant updates to the recently issued accounting standards for the year ended December 31, 2022. Although there are several other new accounting pronouncements issued or proposed by the FASB, based on the Company’s preliminary assessment, the Company does not believe any of those accounting pronouncements have had or will have a material impact on its financial position or operating results.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2022
Fair Value Measurements
Fair Value Measurements	Note 3 – 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 Level 2 Level 3 Financial assets measured at fair value on a recurring basis consist of the Company’s cash equivalents and AFS securities. 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, and bids and/or offers. Investments are classified as Level 1 within the fair value hierarchy if their quoted prices are available in active markets for identical securities. Investments in money market funds and U.S. government securities were classified as Level 1 instruments. Investments in commercial paper, corporate debt securities and U.S. agency bonds are valued using Level 2 inputs. The Company classifies investments within Level 2 if the investments are valued using model driven valuations using observable inputs such as quoted market prices, benchmark yields, reported trades, broker/dealer quotes or alternative pricing sources with reasonable levels of price transparency. Investments are held by custodians who obtain investment prices from a third-party pricing provider that incorporates standard inputs in various asset pricing models. The carrying amounts of cash, prepaid expenses and other current assets, other assets, accounts payable, accrued research and development, other current liabilities and other long-term liabilities are reasonable estimates of their fair value due to the short-term nature of these accounts. The Company’s money market funds under cash and cash equivalents are classified using Level 1 inputs within the fair value hierarchy because they are valued using quoted market prices, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency. There were no transfers between levels of the fair value hierarchy during the years ended December 31, 2022 and 2021. The following table summarizes financial assets that the Company measured at fair value on a recurring basis, classified in accordance with the fair value hierarchy (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at Reporting Date Using: ​ Level 1 Level 2 Level 3 Total As of December 31, 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 8,528 ​ $ — ​ $ — ​ $ 8,528 Commercial paper ​ ​ — ​ ​ 83,423 ​ ​ — ​ ​ 83,423 U.S. government securities ​ ​ 10,837 ​ ​ — ​ ​ — ​ ​ 10,837 U.S. agency bonds ​ ​ — ​ ​ 22,143 ​ ​ — ​ ​ 22,143 Corporate debt securities ​ ​ — ​ ​ 997 ​ ​ — ​ ​ 997 Total cash equivalents and short-term investments ​ $ 19,365 ​ $ 106,563 ​ $ — ​ $ 125,928 Reported as: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents (includes cash of $4,526) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 61,955 Short-term investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 68,499 Total cash, cash equivalents and short-term investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 130,454 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at Reporting Date Using: ​ Level 1 Level 2 Level 3 Total As of December 31, 2021 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 10,585 ​ $ — ​ $ — ​ $ 10,585 Commercial paper ​ ​ — ​ ​ 84,616 ​ ​ — ​ ​ 84,616 U.S. government securities ​ ​ 27,824 ​ ​ — ​ ​ — ​ ​ 27,824 U.S. agency bonds ​ ​ — ​ ​ 8,531 ​ ​ — ​ ​ 8,531 Corporate debt securities ​ ​ — ​ ​ 8,265 ​ ​ — ​ ​ 8,265 Total cash equivalents and short-term investments ​ $ 38,409 ​ $ 101,412 ​ $ — ​ $ 139,821 Reported as: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents (includes cash of $397) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 24,780 Short-term investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 115,438 Total cash, cash equivalents and short-term investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 140,218 ​ There were no liabilities measured at fair value on a recurring basis as of December 31, 2022 and 2021.

Investments

Investments	12 Months Ended
	Dec. 31, 2022
Investments
Investments	Note 4 – Investments We invest in available-for-sale securities consisting of money market funds, commercial paper, U.S. government securities, U.S. agency bonds and corporate debt securities. Available-for-sale securities are classified as either cash and cash equivalents or short-term investments on the consolidated balance sheets. The following table summarizes, by major types of cash equivalents, and investments that are measured at fair value on a recurring basis (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2022 ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Estimated ​ ​ Cost ​ Gains ​ Losses ​ Fair Value Money market funds ​ $ 8,528 ​ $ — ​ $ — ​ $ 8,528 Commercial paper ​ ​ 83,479 ​ ​ 11 ​ ​ (67) ​ ​ 83,423 U.S. government securities ​ ​ 10,910 ​ ​ — ​ ​ (73) ​ ​ 10,837 U.S. agency bonds ​ ​ 22,175 ​ ​ 4 ​ ​ (36) ​ ​ 22,143 Corporate debt securities ​ ​ 1,002 ​ ​ — ​ ​ (5) ​ ​ 997 Cash equivalents and short-term investments ​ $ 126,094 ​ $ 15 ​ $ (181) ​ $ 125,928 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2021 ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Estimated ​ ​ Cost ​ Gains ​ Losses ​ Fair Value Money market funds ​ $ 10,585 ​ $ — ​ $ — ​ $ 10,585 Commercial paper ​ ​ 84,642 ​ ​ 2 ​ ​ (28) ​ ​ 84,616 U.S. government securities ​ ​ 27,870 ​ ​ — ​ ​ (46) ​ ​ 27,824 U.S. agency bonds ​ ​ 8,546 ​ ​ — ​ ​ (15) ​ ​ 8,531 Corporate debt securities ​ ​ 8,267 ​ ​ — ​ ​ (2) ​ ​ 8,265 Cash equivalents and short-term investments ​ $ 139,910 ​ $ 2 ​ $ (91) ​ $ 139,821 ​ The contractual maturities of the Company’s AFS securities were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ 2022 ​ 2021 Due within one year ​ $ 63,595 ​ $ 105,173 Due within one to two years ​ ​ 4,904 ​ ​ 10,265 Total ​ $ 68,499 ​ $ 115,438 ​ The available-for-sale investments are classified as current assets, even though the stated maturity date may be one year or more beyond the current consolidated balance sheet date, which reflects management’s intention to use the proceeds from sales of these securities to fund the Company’s operations, as necessary. There were no realized gains or losses due to investment sales for the years ended December 31, 2022 and 2021. As of December 31, 2022, $85.9 million of the Company’s marketable securities were in gross unrealized loss positions, of which none had been in such position for greater than 12 months and $53.6 million will mature within three months of December 31, 2022. At each reporting date, the Company performs an evaluation of its marketable securities to determine if any unrealized losses are other-than-temporary. Factors considered in determining whether a loss is other-than-temporary include (i) the financial strength of the issuing institution, (ii) the length of time and extent for which fair value has been less than the cost basis and (iii) the Company’s intent and ability to hold its investments in unrealized loss positions until their amortized cost basis has been recovered. Based on the Company’s evaluation, it determined that its unrealized losses were not other-than-temporary at December 31, 2022 and 2021. The Company does not intend to sell the investments before maturity, and it is unlikely that the Company will be required to sell the investments before recovery of their amortized cost bases.

Consolidated Balance Sheet Deta

Consolidated Balance Sheet Details	12 Months Ended
	Dec. 31, 2022
Consolidated Balance Sheet Details
Consolidated Balance Sheet Details	Note 5 – Consolidated Balance Sheet Details Prepaid and Other Current Assets Prepaid and other current assets consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ ​ 2022 ​ 2021 Prepaid research ​ $ 1,103 ​ $ 4,329 Prepaid insurance ​ ​ 913 ​ ​ 827 FICA tax credit receivable ​ ​ 571 ​ ​ 452 Other current assets ​ ​ 152 ​ ​ 205 Prepaid other ​ ​ 416 ​ ​ 96 Deposits ​ ​ 19 ​ ​ 19 Prepaid and other current assets ​ $ 3,174 ​ $ 5,928 ​ Property and equipment, net, consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ ​ 2022 ​ 2021 Furniture and equipment ​ $ 204 ​ $ 204 Leasehold improvements ​ ​ 67 ​ ​ 67 Computer equipment ​ ​ 50 ​ ​ 50 Construction in progress ​ ​ 8 ​ ​ — ​ ​ $ 329 ​ $ 321 Less: accumulated depreciation and amortization expense ​ ​ (236) ​ ​ (156) Property and equipment, net ​ $ 93 ​ $ 165 ​ Depreciation and amortization expense for each of the years ended December 31, 2022 and 2021 was $0.1 million. Other Non-Current Assets Other non-current assets consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ ​ 2022 ​ 2021 Deposits ​ $ 781 ​ $ 75 FICA tax credit receivable ​ ​ 52 ​ ​ 298 Other ​ ​ 368 ​ ​ 70 Other non-current assets ​ $ 1,201 ​ $ 443 ​ ​ Other Accrued Liabilities Other accrued liabilities consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ ​ 2022 ​ 2021 Accrued bonus ​ $ 3,379 ​ $ 1,933 Accrued payroll and related ​ ​ 229 ​ ​ 39 ESPP liability ​ ​ 155 ​ ​ 369 Other ​ ​ 2,661 ​ ​ 3,353 Other accrued liabilities ​ $ 6,424 ​ $ 5,694 ​

Convertible Preferred Stock and

Convertible Preferred Stock and Stockholders' Equity (Deficit)	12 Months Ended
	Dec. 31, 2022
Convertible Preferred Stock and Stockholders' Equity (Deficit)
Convertible Preferred Stock and Stockholders' Equity (Deficit)	Note 6 – Convertible Preferred Stock and Stockholders’ Equity (Deficit) In 2020, the Company amended its Certificate of Incorporation to authorize the issuance of 24,000,000 shares of common stock, par value $0.001 per share, and 16,273,406 shares of preferred stock, par value $0.001 per share, of which 3,731,208 shares were designated Series A convertible preferred stock and 12,542,198 shares were designated Series B convertible preferred stock. In April 2021, the Company filed a certificate of amendment to its certificate of incorporation, which authorized 260,000,000 shares of capital stock, consisting of 250,000,000 shares of common stock, par value $0.001 per share, and 10,000,000 shares of undesignated preferred stock, par value $0.001 per share that may be issued from time to time by the Board of Directors in one or more series. Of the 250,000,000 shares of common stock, 200,000,000 shares were designated as “Common Stock” and 50,000,000 shares were designated as “Non-Voting Common Stock.” Rights, preferences, powers, privileges and restrictions, qualifications and limitations for holders of the Company’s Common Stock and Non-Voting Common Stock are: a) Voting Common Stock Voting Rights . Each holder of Voting Common Stock, as such, shall be entitled to one vote for each share of Voting Common Stock held of record by such holder on all matters on which stockholders generally are entitled to vote; provided, however, that, except as otherwise required by law, holders of Voting Common Stock, as such, shall not be entitled to vote on any amendment to the Certificate of Incorporation, including any certificate of designations relating to any series of Preferred Stock (each hereinafter referred to as a “Preferred Stock Designation”), that relates solely to the terms of one or more outstanding series of Preferred Stock if the holders of such affected series are entitled, either separately or together with the holders of one or more other such series, to vote thereon pursuant to the Certificate of Incorporation (including any Preferred Stock Designation). b) Non-Voting Common Stock Voting Rights . Non-Voting Common Stock (i) shall be non-voting except as may be required by law and (ii) shall not entitle the holder thereof to vote on the election of directors at any time. c) Non-Voting Common Stock Conversion . Each holder of shares of Non-Voting Common Stock shall have the right to convert each share of Non-Voting Common Stock held by such holder into one share (subject to appropriate adjustment in the event of any stock dividend, stock split, reverse stock split, combination or other similar recapitalization with respect to the Voting Common Stock) of Voting Common Stock at such holder’s election by providing written notice to the Company ; provided, however, that such shares of Non-Voting Common Stock may only be converted into shares of Voting Common Stock during such time or times as immediately prior to or as a result of such conversion would not result in the holder(s) thereof beneficially owning (for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended and the rules and regulations promulgated thereunder (collectively, the “Exchange Act”)), when aggregated with affiliates with whom such holder is required to aggregate beneficial ownership for purposes of Section 13(d) of the Exchange Act, in excess of the Beneficial Ownership Limitation. The “Beneficial Ownership Limitation” means initially 9.99% of the Voting Common Stock. Any holder of Non-Voting Common Stock may increase the Beneficial Ownership Limitation with respect to such holder, not to exceed 19.99% of the Voting Common Stock, upon 61 days ’ prior written notice to the Company and may decrease the Beneficial Ownership Limitation at any time upon providing written notice of such election to the Company; provided, however, that no holder may make such an election to change the percentage with respect to such holder unless all holders managed by the same investment advisor as such electing holder make the same election. Before any holder of Non-Voting Common Stock shall be entitled to convert any shares of Non-Voting Common Stock into shares of Voting Common Stock, such holder shall (A) surrender the certificate or certificates therefor (if any), duly endorsed, at the principal corporate office of the Company or of any transfer agent for the Non-Voting Common Stock, and (B) provide written notice to the Company, during regular business hours at its principal corporate office, of such conversion election (in form satisfactory to the Company) and shall state therein the name or names (i) in which the certificate or certificates representing the shares of Voting Common Stock into which the shares of Non-Voting Common Stock are so converted are to be issued (if such shares of Voting Common Stock are certificated) or (ii) in which such shares of Voting Common Stock are to be registered in book-entry form (if such shares of Voting Common Stock are uncertificated). If the shares of Voting Common Stock into which the shares of Non-Voting Common Stock are to be converted are to be issued in a name or names other than the name of the holder of the shares of Non-Voting Common Stock being converted, such notice shall be accompanied by a written instrument or instruments of transfer, in form satisfactory to the Company, duly executed by the holder. The Company shall, as soon as practicable thereafter, issue and deliver at such office to such holder, or to the nominee or nominees of such holder, a certificate or certificates representing the number of shares of Voting Common Stock to which such holder shall be entitled upon such conversion (if such shares of Voting Common Stock are certificated) or shall register such shares of Voting Common Stock in book-entry form (if such shares of Voting Common Stock are uncertificated). Such conversion shall be deemed to be effective immediately prior to the close of business on the date of such surrender of the shares of Non-Voting Common Stock to be converted following or contemporaneously with the provision of written notice of such conversion election as required by this section, the shares of Voting Common Stock issuable upon such conversion shall be deemed to be outstanding as of such time, and the person or persons entitled to receive the shares of Voting Common Stock issuable upon such conversion shall be deemed to be the record holder or holders of such shares of Voting Common Stock as of such time. Notwithstanding anything herein to the contrary, shares of Non-Voting Common Stock represented by a lost, stolen or destroyed stock certificate may be converted if the holder thereof notifies the Company or its transfer agent that such certificate has been lost, stolen or destroyed and makes an affidavit of that fact acceptable to the Company and executes an agreement acceptable to the Company to indemnify the Company from any loss incurred by it in connection with such certificate. The effectiveness of any conversion of any shares of Non-Voting Common Stock into shares of Voting Common Stock is subject to the expiration or early termination of any applicable premerger notification and waiting period requirements of the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, and the rules and regulations promulgated thereunder. d) Dividends . Subject to the rights of the holders of any outstanding series of Preferred Stock, the holders of shares of Common Stock shall be entitled to receive any dividends to the extent permitted by law when, as and if declared by the Board of Directors . e) Liquidation . Upon the dissolution, liquidation or winding up of the Company, subject to the rights of the holders of any outstanding series of Preferred Stock, the holders of shares of Common Stock shall be entitled to receive the assets of the Company available for distribution to its stockholders ratably in proportion to the number of shares held by them. The Non-Voting Common Stock shall rank on parity with the Voting Common Stock as to distributions of assets upon dissolution, liquidation or winding up of the Company, whether voluntary or involuntary. Convertible Preferred Stock Series A Convertible Preferred Stock. Series B Convertible Preferred Stock. Rights, preferences, powers, privileges and restrictions, qualifications and limitations for holders of the Company’s Series A convertible preferred stock and Series B convertible preferred stock were: ● Dividends: Each holder of the Company’s Series A and Series B convertible preferred stock was entitled to receive non-cumulative dividends, when and if declared by the Board of Directors. No dividends have been declared to date. ● Liquidation Preferences: In the event of any liquidation, dissolution or winding up of the Company, the holders of the Series A and Series B convertible preferred stock were entitled to receive, prior and in preference to any distribution of any of the assets of the Company to the holders of common stock, an amount per share equal to the original issue price plus declared but unpaid dividends. ● Conversion: Each share of Series A and Series B convertible preferred stock was convertible at the option of the holder, at any time, into the number of shares of common stock determined by dividing the applicable purchase price by the applicable conversion price at the time of conversion. Each share of Series A and Series B convertible preferred stock will be automatically converted into common stock immediately upon (i) the closing of a firm commitment underwritten IPO resulting in at least $50.0 million of gross proceeds to the Company or (ii) the receipt by the Company of a written request for automatic conversion from the holders of a majority of the outstanding shares of Series A and Series B convertible preferred stock. ● Voting: The holders of the Series A and Series B convertible preferred stock were entitled to one vote for each share of common stock into which such shares of Series A and Series B convertible preferred stock could then be converted; and with respect to such vote, such holders shall have full voting rights and powers equal to the voting rights and powers of the holders of the common stock. ● Redemption: The Series A and Series B convertible preferred stock were not explicitly redeemable at the option of the holder at a specified date in the future or at the option of the Company. Prior to the IPO, the Company’s Series A and Series B convertible preferred stock were classified as temporary equity on the consolidated balance sheet instead of in stockholders’ equity (deficit), as events triggering redemption that were not solely within the Company’s control because the preferred stockholders had the ability to effect a liquidation event. The Company determined not to adjust the carrying values of the Series A and Series B convertible preferred stock to the liquidation preferences of such shares because of the uncertainty of whether or when such liquidation events would occur. On April 27, 2021, immediately prior to the closing of the IPO, 8,344,905 shares of the Company’s convertible preferred stock were exchanged for 7,727,470 shares of Non-Voting Common Stock and 7,928,501 shares of the Company’s convertible preferred stock converted into 7,341,860 shares of Common Stock. There were no outstanding shares of the Company’s convertible preferred stock as of December 31, 2022 and 2021. Equity Incentive Plan In August 2020, the Board of Directors amended the Amended and Restated 2018 Stock Option—Stock Issuance Plan (the “2018 Plan”) to increase the maximum number of shares of common stock that may be issued over the term of the plan. The 2018 Plan provided for the grant of stock options, non-statutory stock options, incentive stock options and stock issuances to employees, nonemployees and consultants of the Company. In April 2021, the Company’s 2021 Equity Incentive Plan (the “2021 Plan”) was approved by the Board of Directors and became effective on April 15, 2021. Upon the effectiveness of the 2021 Plan, no further grants may be made under the 2018 Plan. The 2021 Plan allows the Company to grant equity-based awards to its officers, employees, directors and other key persons (including consultants). The Company initially reserved up to 3,246,120 shares of common stock for issuance under the 2021 Plan, plus (i) 1,722 shares that remained available for the issuance of awards under the 2018 Plan at the time the 2021 Plan became effective, and (ii) any shares subject to outstanding options or other share awards that were granted under the 2018 Plan that terminate or expire prior to exercise or settlement; are forfeited because of the failure to vest; or are reacquired or withheld (or not issued) to satisfy a tax withholding obligation or the purchase or exercise price. The 2021 Plan provides that the number of shares reserved and available for issuance under the plan will automatically increase each January 1, beginning on January 1, 2022 and each January 1 thereafter through January 31, 2032, by 4.0% of the outstanding number of shares of common stock on the immediately preceding December 31, or such lesser number of shares as determined by the Board of Directors. As a result, the number of shares of common stock reserved for issuance under the 2021 Plan increased by 1,451,611 shares on January 1, 2023. Stock Options A summary of the Company’s stock option activities during the year ended December 31, 2022 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ Weighted- ​ ​ ​ ​ ​ ​ Average ​ Average ​ Aggregate ​ ​ ​ ​ Exercise ​ Remaining ​ Intrinsic ​ ​ ​ ​ Price Per ​ Contract Term ​ Value ​ ​ Total Options ​ Share ​ (in years) ​ (in millions) Outstanding as of December 31, 2021 ​ 1,734,696 ​ $ 8.50 ​ 8.8 ​ $ 7.6 Granted ​ 1,197,328 ​ $ 7.99 ​ ​ ​ ​ ​ Exercised ​ (40,220) ​ $ 4.20 ​ ​ ​ ​ ​ Forfeited or cancelled ​ (298,043) ​ $ 10.72 ​ ​ ​ ​ ​ Outstanding as of December 31, 2022 ​ 2,593,761 ​ $ 8.08 ​ 8.2 ​ $ 5.3 Vested and expected to vest as of December 31, 2022 ​ 2,593,761 ​ $ 8.08 ​ 8.2 ​ $ 5.3 Vested and exercisable as of December 31, 2022 ​ 988,166 ​ $ 6.86 ​ 7.1 ​ $ 3.0 ​ The weighted-average grant date fair values of option grants during the years ended December 31, 2022 and 2021 were $6.61 and $12.14 per share, respectively. The weighted-average grant date fair values of options forfeited during the years ended December 31, 2022 and 2021 were $9.35 and $6.08 per share, respectively. Restricted Stock Units A summary of the Company’s RSU activities during the year ended December 31, 2022 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ Aggregate ​ ​ Total ​ Average ​ Intrinsic ​ ​ Restricted ​ Grant Date ​ Value ​ ​ Stock Units ​ Fair Values ​ (in millions) Outstanding as of December 31, 2021 ​ — ​ $ — ​ $ — Granted ​ 9,289 ​ $ 6.25 ​ ​ ​ Vested ​ — ​ $ — ​ ​ ​ Forfeited or cancelled ​ (344) ​ $ 6.25 ​ ​ ​ Outstanding as of December 31, 2022 ​ 8,945 ​ $ 6.25 ​ $ 0.1 ​ There were no RSUs vested during the year ended December 31, 2022. Employee Stock Purchase Plan The ESPP was approved by the Board of Directors and became effective on April 15, 2021. The ESPP initially reserved and authorized the issuance of up to 259,689 shares of common stock to participating employees. Under the ESPP, eligible employees can contribute up to 15% of their eligible compensation, as defined in the ESPP, towards the purchase of the Company’s common stock at a price of 85% of the lower of the fair market value of the Company’s common stock on the first trading day of the offering period or on the last trading day of the offering period. The ESPP provides for twenty-four-month offering periods with four six-month purchase periods in each offering period. The ESPP provides that the number of shares reserved and available for issuance will automatically increase each January 1, beginning on January 1, 2022 and each January 1 thereafter through January 31, 2032, by 1.0% of the total number of shares of common stock outstanding on December 31 of the preceding calendar year. As a result, the number of shares of common stock reserved for issuance under the ESPP increased by 362,902 shares on January 1, 2023. Under the ESPP, the Company issued 57,862 shares of common stock for aggregate cash proceeds of $0.4 million during the year ended December 31, 2022. Stock-Based Compensation Expense The Company recognized stock-based compensation expense as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2022 2021 Research and development ​ $ 3,782 ​ $ 2,486 General and administrative ​ ​ 1,073 ​ ​ 606 Total stock-based compensation expense ​ $ 4,855 ​ $ 3,092 ​ The weighted-average assumptions used in the Black-Scholes option pricing model to determine the fair value of the stock option grants were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2022 2021 Risk-free interest rate ​ ​ 1.6% - 4.3% ​ ​ 0.8% - 1.3% Expected volatility ​ ​ 88.1% - 112.1% ​ ​ 113.2% - 118.7% Expected term (in years) ​ ​ 5.3 - 6.1 ​ ​ 5.0 – 6.1 Expected dividend yield ​ ​ 0% ​ ​ 0% ​ As of December 31, 2022, the total unrecognized compensation cost related to outstanding stock options and restricted stock units was $10.7 million and is expected to be recognized as expense over approximately 2.6 years. The weighted average assumptions used in the Black-Scholes option pricing model to estimate the fair value of purchase rights granted under the ESPP were as follows: ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2022 ​ 2021 Risk-free interest rate ​ 0.2% ​ 0.1% Expected volatility ​ 139.6% ​ 127.8% Expected term (in years) ​ 2.2 ​ 1.4 Expected dividend yield ​ 0% ​ 0% ​ As of December 31, 2022, there was $0.1 million of unrecognized compensation cost related to the ESPP and is expected to be recognized over approximately 0.5 years. The determination of the fair value of share-based payment awards utilizing the Black-Scholes option-pricing model is affected by the Company’s stock price and the following assumptions: Risk-free interest rate. Expected volatility. Expected term. Expected dividend yield. Forfeitures Common Stock Reserved for Future Issuance Common stock reserved for future issuance consist of the following: ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ 2022 2021 Stock options ​ 2,593,761 ​ 1,734,696 Restricted stock units ​ 8,945 ​ — Reserved for future equity award grants ​ 3,084,732 ​ 2,933,930 Reserved for future ESPP issuances ​ 466,585 ​ 259,689 Common stock reserved for future issuance ​ 6,154,023 ​ 4,928,315 ​

License Agreements

License Agreements	12 Months Ended
	Dec. 31, 2022
License Agreements
License Agreements	Note 7 – License Agreements The Company has entered into license agreements, accounted for as asset acquisitions, under which the Company is required to use commercially reasonable efforts to meet certain specified development and regulatory milestones related to the licensed technologies within specified time periods. In consideration of the rights granted to the Company under the agreements, the Company is required to make cash milestone payments to the licensors upon the completion of certain development, regulatory and commercial milestones. For the arrangements that the Company accounted for as asset acquisitions, contingent consideration liabilities are recorded as an additional cost of the acquired assets when the contingency is resolved, and the consideration is paid or becomes payable. Additionally, the Company has agreed to pay royalties on net sales of products applicable to the license agreements. The Company may terminate the agreements upon written notice to the licensors. Daiichi Sankyo License Agreement On September 2, 2020, the Company licensed the rights to milademetan (DS-3032b) for all human prophylactic or therapeutic uses in all countries and territories of the world from Daiichi Sankyo (the “Daiichi Sankyo License Agreement”). Daiichi Sankyo conducted clinical studies of milademetan prior to the Company’s licensing the rights to this product. The Company refers to this product candidate as milademetan. In accordance with the terms of the Daiichi Sankyo License Agreement, the Company paid Daiichi Sankyo an initial upfront payment of $5.0 million in September 2020. Under the Daiichi Sankyo License Agreement, the Company obtained worldwide, sublicensable exclusive rights to seven families of patents with respect to milademetan (the “Licensed Compound”). The Company is solely responsible under the Daiichi Sankyo License Agreement for the research, development and registration of milademetan. Pursuant to the Daiichi Sankyo License Agreement, Daiichi Sankyo had the right to continue to conduct three clinical trials and prepare final reports with respect to these clinical trials, and such right expires upon all subjects completing the study treatment. The Company has agreed to reimburse Daiichi Sankyo certain third-party expenses incurred while conducting such trials. On March 3, 2022, the Company and Daiichi Sankyo entered into a Memorandum of Understanding, which provides that Daiichi Sankyo will terminate its U105 study, and the Company will reimburse a total of $2.0 million to Daiichi Sankyo for expenses related to such study in four installments of $0.5 million each until December 31, 2022. As of December 31, 2022, the Company paid total installments of $1.5 million and the remaining $0.5 million installment as of December 31, 2022 has been paid in full The Company is required to make aggregate future milestone payments of up to $223.5 million, contingent on the attainment of certain development, regulatory and sales milestones. The $223.5 million aggregate future milestone payments include a $2.0 million increase that was agreed upon in the Memorandum of Understanding with Daiichi Sankyo. On July 20, 2021, the Company announced that the first patient has been randomized in the multicenter, open-label, Phase 3 registrational trial (MANTRA) evaluating milademetan for the treatment of de-differentiated liposarcoma. Accordingly, pursuant to the Daiichi Sankyo License Agreement, the Company recorded $5.5 million in milestone fees as research and development expense in the consolidated statement of operations and comprehensive loss during the year ended December 31, 2021. Of the $5.5 million milestone fees, $2.5 million was paid in the third quarter of 2021 and $3.0 million was accrued as part of accrued research and development in the consolidated balance sheet as of December 31, 2021. On June 29, 2022, the Company and Daiichi Sankyo entered into an amendment to the Daiichi Sankyo License Agreement. The amendment reduced the $3.0 million milestone fee liability associated with the previously achieved milestone to $2.0 million and accordingly reduced research and development expense on the consolidated statements of operations and comprehensive loss by $1.0 million for the year ended December 31, 2022. The amendment also extended the due date of the milestone fee payment to June 30, 2023. During the year ended December 31, 2022, the Company incurred no milestone research and development expense under the Daiichi Sankyo License Agreement. Additionally, the Company is required to pay Daiichi Sankyo a high single digit royalty based on the annual net sales of products containing milademetan as an active pharmaceutical ingredient (the Products), subject to reduction at an agreed rate upon expiration of the licensed patent in the particular country where the Products are sold. To date, no royalty payments have been made to Daiichi Sankyo under the Daiichi Sankyo License Agreement. The royalty obligation terminates on a country-by-country and on a product-by-product basis on the later of: (i) loss of all market exclusivity for such Product in such country, (ii) the last-to-expire patent that covers the Licensed Compound or the Product in such country and (iii) twelve years from launch of the first Product sold by the Company in such country. Unless sooner terminated or extended, the Daiichi Sankyo License Agreement will remain in full force and effect until the Company, its affiliates and its sublicensees cease all development and commercial activity related to milademetan. Either party may terminate the Daiichi Sankyo License Agreement for cause in the event of an uncured material breach (subject to a 90-day cure period). However, the Company may only terminate the Daiichi Sankyo License Agreement with respect to the countries affected by such uncured material breach. Daiichi Sankyo may also terminate the Daiichi Sankyo License Agreement in the event of Rain’s bankruptcy or insolvency. Additionally, Daiichi Sankyo may terminate the Daiichi Sankyo License Agreement immediately upon written notice if the Company, its affiliates or its sublicensors initiate or join any challenge to the validity or enforceability of a licensed patent, subject to certain exclusions. Furthermore, the Company may terminate the Daiichi Sankyo License Agreement in its entirety or on a country-by-country basis for bona fide material concerns regarding the (i) lack of safety for human use arising from toxicity of the Licensed Compound or Product(s), (ii) lack of efficacy of the Licensed Compound or Product(s) or (iii) adverse economic impact to the Company in connection with its continued development of the Products, in each case, upon six months’ prior written notice to Daiichi Sankyo. In addition, if the Company is acquired by a third party that is developing and commercializing a competing compound and the acquiring party decides not to discontinue the development or commercialization of such competing compound, such third party must terminate the Daiichi Sankyo License Agreement within 30 days of such acquisition if it does not discontinue such development or commercialization. Upon termination of the Daiichi Sankyo License Agreement by Daiichi Sankyo for the Company’s uncured material breach or by the Company for its bona fide material concerns regarding the safety, efficacy or adverse economic impacts relating to the Licensed Compound or Products, or its development thereof, the Company is required to, among other actions, if requested by Daiichi Sankyo (i) transfer to Daiichi Sankyo ongoing clinical trials, data, reports, records and materials, (ii) grant to Daiichi Sankyo an exclusive, irrevocable, sublicensable, fully paid-up license under any patents and know-how that are controlled and actually used by the Company at the time of termination in connection with the Products to allow Daiichi Sankyo exploit the Licensed Compound or Products in countries that are affected by the termination, (iii) grant to Daiichi Sankyo an exclusive, irrevocable, sublicensable, fully paid up license to use trademarks that are specific to the Products and (iv) assign any applicable sublicenses. Drexel License Agreement and Sponsored Research Agreement On July 30, 2020, the Company entered into an intellectual property license agreement (the “Drexel License Agreement”) with Drexel University (“Drexel”). Pursuant to the Drexel License Agreement, Drexel granted to the Company a license to make and commercialize products related to RAD52 inhibitors for the treatment of cancer. The Company made payments of $53,118 and $34,387 under the Drexel License Agreement for the years ended December 31, 2022 and 2021, respectively. In February 2023, the Company decided to discontinue further development of its preclinical program focused on targeting RAD52 in the DNA damage repair pathway, and the Company notified Drexel of the termination of the Drexel License Agreement pursuant to its terms to focus use of financial and personnel resources on the milademetan clinical program. Roche Clinical Supply Agreement In December 2021, the Company entered into a clinical supply agreement with Roche for the supply of the anti-Programmed Death Ligand-1 (PD-L1) monoclonal antibody, atezolizumab. Clinical trials are planned to evaluate milademetan, in combination with atezolizumab for the treatment of patients in genetically selected populations. Under this agreement, Rain is the sponsor of the anticipated clinical trials, and Roche will supply atezolizumab. The Company does not have any financial commitments to Roche under this agreement.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies.
Commitments and Contingencies	Note 8 – Commitments and Contingencies Leases In September 2018, the Company entered into a noncancelable operating lease agreement for office space for its corporate headquarters in Newark, California with an initial term of 5.25 years. The lease commenced in January 2019 and ends March 2024. Under the terms of the lease, the Company pays annual base rent, subject to an annual fixed percentage increase of 2% on March 1st of each year. The Company is obligated to pay for its share of direct expenses including operating expense and taxes, which are considered variable lease costs and are expensed as incurred. In March 2020, Governor Newsom issued State of California Executive Order No. N-33-20 instructing all individuals in California to stay at home due to the COVID-19 pandemic. In connection with such order, the Company entered into an amendment to the noncancelable operating lease agreement in June 2020. The amendment provided the Company rent relief for three months in 2020. In consideration of the rent relief, the Company agreed to adjust the base rent annual fixed percentage increase of 3% on February 1st of each year and extend the lease until September 2024. The amendment was determined to be a lease modification that qualified as a change of accounting on the existing lease and not a separate contract. Remeasurement of the right-of-use asset and operating lease liabilities at the date of modification did not result in a material increase of the right-of-use asset and operating lease liabilities. In October 2022, the Company entered into an amendment to its corporate headquarters lease agreement to expand the leased premises by approximately 3,880 square feet. The lease commencement date for the expansion premises is expected to be March 2023 and will expire in November 2024 concurrently with the existing lease. Total future lease payments over the life of the lease are estimated to increase by approximately $0.3 million as a result of the amendment. The future minimum lease payments required under the operating lease are summarized as follows (in thousands): ​ ​ ​ ​ ​ As of December 31, 2022 2023 ​ $ 171 2024 ​ ​ 129 2025 ​ ​ — Total minimum lease payments ​ $ 300 Less: amount representing interest ​ ​ (23) Present value of operating lease liabilities ​ $ 277 Operating lease liabilities, current ​ ​ 164 Operating lease liabilities, non-current ​ ​ 113 Total operating lease liabilities ​ $ 277 ​ ​ ​ ​ Weighted-average remaining lease term (in years) ​ ​ 1.7 Weighted-average incremental borrowing rate ​ ​ 10.0% ​ In addition to what is included in the table above, the future minimum lease payments for the operating lease not yet commenced are summarized as follows (in thousands): ​ ​ ​ ​ ​ As of December 31, 2022 2023 ​ $ 144 2024 ​ ​ 158 2025 ​ ​ — Total minimum lease payments ​ $ 302 ​ The table below summarizes the Company’s lease costs and cash payments in connection with operating lease obligations (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2022 ​ 2021 2020 Total operating lease expense $ 160 ​ $ 160 ​ $ 130 Operating cash flows used for operating lease ​ $ 167 ​ $ 162 ​ $ 130 ​ Contingencies In the event the Company becomes subject to claims or suits arising in the ordinary course of business, the Company would accrue a liability for such matters when it is probable that future expenditures will be made, and such expenditures can be reasonably estimated.

Employee Benefits

Employee Benefits	12 Months Ended
	Dec. 31, 2022
Employee Benefits
Employee Benefits	Note 9 – Employee Benefits The Company has a defined contribution 401(k) plan available to eligible employees. Under the terms of the plan, employees may make voluntary contributions as a percent of compensation, limited to the maximum amount allowable under federal tax regulations. The Company, at its discretion, may make certain contributions to the 401(k) plan. The Company made matching contributions of $541,471 and $233,831 for the years ended December 31, 2022 and 2021, respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2022
Income Taxes
Income Taxes	Note 10 – Income Taxes The Company recorded de minimis state income tax expense for the years ended December 31, 2022 and 2021 primarily as a result of the Company maintaining a full valuation allowance against its loss from operations for tax purposes. The net losses for the years ended December 31, 2022 and 2021 were generated solely in the United States. The provision for income taxes is comprised of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2022 2021 Current: ​ ​ ​ ​ ​ ​ State $ 3 ​ $ 2 Provision for income taxes ​ $ 3 ​ $ 2 ​ The provision for income taxes differs from the amount computed by applying the federal statutory income tax rate to income before taxes as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2022 2021 Federal tax benefit at statutory rate ​ $ (15,901) ​ $ (10,792) State taxes ​ ​ (6,867) ​ ​ 604 Non-deductible expenses ​ ​ 539 ​ ​ 490 R&D credits ​ ​ (4,807) ​ ​ (2,177) Change in valuation allowance ​ ​ 31,449 ​ ​ 11,870 Return-to-provision adjustment ​ ​ (4,341) ​ ​ — Other ​ ​ (69) ​ ​ 7 Provision for income taxes ​ $ 3 ​ $ 2 ​ The Company petitioned for a ruling with the California Franchise Tax Board to apply an alternate apportionment method in California and the ruling was approved in November 2022. As a result of the ruling, the Company recorded a $3.4 million return-to-provision adjustment to true up the California net operating losses (NOL) deferred tax asset in the 2022 provision. The return to provision adjustment of the California NOL deferred tax asset is fully offset by a valuation allowance. Deferred income taxes reflect the tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The components of deferred income tax assets and liabilities are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ 2022 2021 Deferred tax assets: ​ ​ ​ ​ ​ Accrued expenses and other ​ $ 1,045 $ 407 Fixed assets ​ ​ 19 ​ ​ 10 Intangibles ​ ​ 2,915 ​ ​ 2,378 Net operating losses ​ ​ 29,151 ​ ​ 16,993 R&D and Orphan Drug credits ​ ​ 8,384 ​ ​ 2,615 Section 174 capitalization ​ ​ 11,509 ​ ​ — Stock-based compensation ​ ​ 1,100 ​ ​ 287 Lease liability ​ ​ 80 ​ ​ 87 Other ​ ​ 18 ​ ​ 2 Total deferred tax assets ​ $ 54,221 ​ $ 22,779 Valuation allowance ​ ​ (54,146) ​ ​ (22,698) Total net deferred tax assets ​ $ 75 ​ $ 81 Deferred tax liabilities: ​ ​ ​ ​ ​ ​ Right-of-use asset ​ $ (75) ​ ​ (81) Total deferred tax liabilities ​ $ (75) ​ $ (81) Net deferred tax assets ​ $ — ​ $ — ​ Realization of deferred tax assets is dependent upon the Company’s ability to generate sufficient taxable income within the carryforward period. In assessing the realizability of some portion or all of the deferred tax assets, the Company evaluated both positive and negative evidence to determine if some or all of its deferred tax assets should be recognized. Based on the available objective evidence, the Company has concluded it is not more likely than not that its deferred tax assets will be realized. Therefore, a valuation allowance in the amount of $54.1 million has been recorded for 2022 against the Company’s deferred tax assets. The net valuation allowance increased by $31.4 million and $11.9 million during the years ended December 31, 2022 and 2021, respectively. The following table sets forth the Company’s federal and state net operating loss and R&D credits carryforwards as of December 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ Amount Expiration Years Net operating losses, Federal—pre TCJA $ 159 ​ 2037 Net operating losses, Federal—post TCJA ​ $ 84,927 ​ N/A Net operating losses, state ​ $ 127,790 ​ 2031-2042 R&D and Orphan Drug credits, Federal ​ $ 10,666 ​ 2039-2042 R&D credits, California ​ $ 1,739 ​ N/A ​ Utilization of the Company’s net operating loss and R&D credits may be subject to substantial limitations due to the ownership changes limitations provided by the Internal Revenue Code and similar state provisions. Such annual limitation could result in the expiration of the net operating loss before their utilization. Sections 382 and 383 of the Internal Revenue Code (“IRC Sections 382 and 383”) impose limitations on a corporation’s ability to utilize its net operating losses and credit carryforwards if it experiences an “ownership change” as defined by IRC Sections 382 and 383. The Company has performed an analysis under Section 382 of the Internal Revenue Code which subjects the amount of pre-change net operating losses and certain other tax attributes that can be utilized to an annual limitation. Based on the analysis, ownership changes have occurred in 2018 and 2021. There had been no additional ownership changes in 2022. The Company is required to recognize in the financial statements the impact of a tax position, if that position is more likely than not of being sustained on audit, based on the technical merits of the position. The following table reflects changes in the gross unrecognized tax benefits (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2022 2021 Balance at beginning of year $ 1,442 $ 402 Additions based on tax positions related to current year ​ ​ 2,167 ​ ​ 1,040 Additions to tax position of prior years ​ ​ 432 ​ ​ — Reductions to tax position of prior years ​ ​ (19) ​ ​ — Balance at end of year ​ $ 4,022 ​ $ 1,442 ​ The Company recognizes interest and penalties as a component of income tax expense. There were no interest or penalties recognized in the statements of operations and comprehensive loss. The total unrecognized tax benefits of $4.0 million and $1.4 million were recorded as of December 31, 2022 and 2021, respectively, which, if recognized currently, should not impact the effective tax rate due to the Company maintaining a full valuation allowance. The Company expects the unrecognized tax benefits will not change significantly within the next 12 months. The Company is subject to examination by the United States federal and state tax authorities for the tax years 2017 and later. The Inflation Reduction Act of 2022 (“IRA”) was signed into law on August 16, 2022. The bill was meant to address the high inflation rate in the United States through various climate, energy, healthcare and other incentives. These incentives are meant to be paid for by the tax provisions included in the IRA, such as a new 15 percent corporate minimum tax, a 1 percent new excise tax on stock buybacks, additional IRS funding to improve taxpayer compliance and other provisions. At this time, none of the IRA tax provisions are expected to have a material impact to the Company’s tax provision. The Company will continue to monitor updates to the Company’s business along with guidance issued with respect to the IRA to determine whether any adjustments are needed to the Company’s tax provision in future periods. Effective for tax years beginning on or after January 1, 2022, pursuant to the Tax Cuts and Jobs Act of 2017, companies are required to capitalize and amortize Internal Revenue Code Section 174 research and experimental expenses paid or incurred over 5 years for research and development performed in the United States and 15 years for research and development performed outside of the United States. As a result of the Internal Revenue Code Section 174 research and experimental expense capitalization, the Company recognized a deferred tax asset for the future tax benefit of the amortization deductions with an offsetting increase in the valuation allowance on deferred tax assets.

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2022
Net Loss Per Share
Net Loss Per Share	Note 11 – Net Loss Per Share The following tables summarize the computation of the basic and diluted net loss per share (in thousands, except share and per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2022 2021 Numerator: ​ ​ ​ ​ ​ ​ Net loss $ (75,724) $ (51,394) Denominator: ​ ​ ​ ​ ​ ​ Weighted-average shares of common stock outstanding, basic and diluted ​ ​ 27,985,446 ​ ​ 19,405,833 Weighted-average shares used to compute net loss per share, basic and diluted ​ ​ 27,985,446 ​ ​ 19,405,833 Net loss per share, basic and diluted ​ $ (2.71) ​ $ (2.65) ​ The following table sets forth the outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share because their inclusion would be anti-dilutive: ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ 2022 2021 Stock options ​ 2,593,761 ​ 1,734,696 Restricted stock units ​ 8,945 ​ — ESPP shares ​ 43,757 ​ 85,031 Total ​ 2,646,463 ​ 1,819,727 ​

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2022
Subsequent Events
Subsequent Events	Note 12 – Subsequent Events In February 2023, a holder of non-voting common stock converted 500,000 shares of non-voting common stock into an equal number of shares of common stock. As of February 28, 2023, there were 9,842,720 shares of non-voting common stock outstanding. In January and February 2023, the Company sold an aggregate of 32,000 shares of common stock in “at-the-market” offerings pursuant to its sales agreement with Oppenheimer & Co. Inc. as sales agent, for net proceeds of $0.3 million, net of commissions and offering expenses. In February 2023, the Company decided to discontinue further development of its preclinical program focused on targeting RAD52 in the DNA damage repair pathway, and the Company notified Drexel of the termination of the Drexel License Agreement pursuant to its terms to focus use of financial and personnel resources on the milademetan clinical program.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2022
Summary of Significant Accounting Policies
Use of Estimates	Use of Estimates The preparation of the Company’s consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that impact the reported amounts of assets, liabilities and expenses and the disclosure of contingent liabilities in the Company’s consolidated financial statements and accompanying notes. The most significant estimate in the Company’s consolidated financial statements relates to the clinical trial expense accruals. Management evaluates its estimates on an ongoing basis. Although these estimates are based on the Company’s historical experience, knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents. Cash equivalents include commercial paper and money market funds.
Available-for-Sale Investments	Available-for-Sale Investments The Company holds investment grade securities consisting of commercial paper, corporate debt securities, U.S. government securities and U.S. agency bonds, classified as available-for-sale (AFS) securities at the time of purchase, since it is the Company’s intent that these investments be available for current operations. The Company has classified all of its AFS securities as current assets on the consolidated balance sheets even though the stated maturity date may be one year or more beyond the current consolidated balance sheet date, which reflects management’s intention to use the proceeds from sales of these securities to fund its operations, as necessary. The Company carries these securities at fair value and reports unrealized gains and losses, if any, as a separate component of accumulated other comprehensive loss. The cost of debt securities is adjusted for amortization of purchase premiums and accretion of discounts to maturity. Such amortization and accretion are included in interest income (expense) in the consolidated statements of operations and comprehensive loss. Realized gains and losses on sales of securities are determined using the specific identification method and recorded in other income (expense), net in the consolidated statement of operations and comprehensive loss. Investments are considered to be impaired when a decline in fair value is judged to be other-than-temporary. The Company consults with its investment managers and considers available quantitative and qualitative evidence in evaluating potential impairment of its investments on a quarterly basis. If the cost of an individual investment exceeds its fair value, the Company evaluates among other factors, general market conditions, the duration and extent to which the fair value is less than cost, and the Company’s intent and ability to hold the investment. Once an impairment is determined to be other-than-temporary, an impairment charge is recorded and a new cost basis in the investment is established. Declines in the value of AFS securities determined to be other than temporary are included in other income (expense), net.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amounts of all cash equivalents, prepaid expenses and other assets, accounts payable and accrued and other current liabilities are reasonable estimates of their fair value because of the short-term nature of these items.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments, which potentially subject the Company to significant concentration of credit risk, consist primarily of cash, cash equivalents and short-term investments. The Company maintains cash and money market deposits in a federally insured major financial institution in excess of federally insured limits. The Company has not experienced any losses in such accounts and management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institution in which those deposits are held.
Research and Development Costs	Research and Development Costs Research and development costs primarily consist of costs associated with the Company’s research and development activities, including its drug discovery efforts, and the preclinical and clinical development of its product candidates. Research and development costs are expensed as incurred.
Property and Equipment	Property and Equipment Property and equipment, net consists of computer equipment, furniture and equipment and leasehold improvements. Leasehold improvements are amortized over the shorter of the estimated useful life or the remainder of the lease term. Computer equipment and furniture and equipment are recorded at cost and depreciated using the straight-line method over the estimated useful lives of the assets (generally two
Long-Lived Assets	Long-Lived Assets The Company regularly reviews the carrying value and estimated lives of all of its long-lived assets, including property and equipment, to determine whether indicators of impairment may exist which warrant adjustments to carrying values or estimated useful lives. Should an impairment exist, the impairment loss would be measured based on the excess over the carrying amount of the asset’s fair value. The Company has not recognized any impairment losses from inception through December 31, 2022.
Commitments	Commitments The Company recognizes a liability with regard to loss contingencies when it believes it is probable that a liability has occurred, and the amount can be reasonably estimated. If some amount within a range of loss appears at the time to be a better estimate than any other amount within the range, the Company accrues that amount. When no amount within the range is a better estimate than any other amount, the Company accrues the minimum amount in the range. The Company has not recorded any such liabilities as of December 31, 2022.
Leases	Leases At the inception of a contractual arrangement, the Company determines whether the contract contains a lease by assessing whether there is an identified asset and whether the contract conveys the right to control the use of the identified asset in exchange for consideration over a period of time. If both criteria are met, the Company records the associated lease liability and corresponding right-of-use asset upon commencement of the lease using the implicit rate or a discount rate based on a credit- adjusted secured borrowing rate commensurate with the term of the lease. The Company additionally evaluates leases at their inception to determine if they are to be accounted for as an operating lease or a finance lease. Operating lease assets represent a right to use an underlying asset for the lease term and operating lease liabilities represent an obligation to make lease payments arising from the lease. Operating lease liabilities with a term greater than one year and their corresponding right-of-use assets are recognized on the consolidated balance sheet at the commencement date of the lease based on the present value of lease payments over the expected lease term. Certain adjustments to the right-of-use asset may be required for items such as initial direct costs paid or incentives received. As the Company’s leases do not typically provide an implicit rate, the Company utilizes the appropriate incremental borrowing rate, determined as the rate of interest that the Company would have to pay to borrow on a collateralized basis over a similar term and in a similar economic environment. Lease cost is recognized on a straight-line basis over the lease term and variable lease payments are recognized as operating expenses in the period in which the obligation for those payments is incurred. Variable lease payments primarily include common area maintenance, utilities, real estate taxes, insurance and other operating costs that are passed on from the lessor in proportion to the space leased by the Company. The Company has elected the practical expedient to not separate lease and non-lease components.
Preclinical Studies and Clinical Trial Accruals	Preclinical Studies and Clinical Trial Accruals The Company is required to estimate its expenses resulting from its obligations under contracts with vendors, consultants, clinical research organizations and clinical site agreements in connection with conducting preclinical activities and clinical trials. The financial terms of these contracts are subject to negotiations which vary from contract to contract and may result in payment flows that do not match the periods over which materials or services are provided under such contracts. The Company reflects preclinical study and clinical trial expenses in its consolidated financial statements by matching those expenses with the period in which services and efforts are expended. The Company accounts for these expenses according to the progress of the preclinical study or clinical trial as measured by the timing of various aspects of the preclinical study, clinical trial or related activities. The Company determines accrual and prepaid estimates through review of the underlying contracts along with preparation of financial models taking into account correspondence with clinical and other key personnel and third- party service providers as to the progress of preclinical studies, clinical trials or other services being conducted. During the course of a preclinical study or clinical trial, the Company adjusts its expense recognition if actual results differ from its estimates. To date, the Company has not experienced any material differences between accrued costs and actual costs incurred.
In-Process Research and Development	In-Process Research and Development The Company evaluates whether acquired intangible assets are a business under applicable accounting standards. Additionally, the Company evaluates whether the acquired assets have a future alternative use. Intangible assets that do not have future alternative use, such as the license the Company acquired from Daiichi Sankyo Company, Limited, (Daiichi Sankyo), are considered acquired in-process research and development. When the acquired in-process research and development assets are not part of a business combination, the value of the consideration paid is expensed on the acquisition date. Future costs to develop these assets are recorded to research and development expenses as they are incurred.
Patent Costs	Patent Costs Costs related to filing and pursuing patent applications are recorded as general and administrative expense and expensed as incurred since recoverability of such expenditures is uncertain.
General and Administrative Expenses	General and Administrative Expenses General and administrative expenses consist of salaries, stock-based compensation, facilities and third-party expenses. General and administrative expenses are associated with the activities of the executive, finance, accounting, information technology, legal and human resource functions.
Stock-Based Compensation	Stock-Based Compensation Stock-based compensation expense represents the grant date fair value of equity awards recognized over the requisite service period of the awards (generally the vesting period) on a straight-line basis. The Company recognizes forfeitures as they occur. The Company estimates the fair value of stock option grants using the Black-Scholes option pricing model. The fair value of restricted stock units (“RSUs”) granted is based on the Company’s closing stock price on the date of grant. Prior to the IPO, the exercise price for all stock options granted was at the estimated fair value of the underlying common stock as determined on the date of grant by the Board of Directors.
Income Taxes	Income Taxes The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the consolidated financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date. The Company recognizes deferred tax assets to the extent that the Company believes these assets are more likely than not to be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies and results of recent operations. If management determines that the Company would be able to realize its deferred tax assets in the future in excess of their recorded amount, management would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. The Company records uncertain tax positions on the basis of a two-step process whereby (1) management determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more likely than not recognition threshold, management recognizes the largest amount of tax benefit that is more than 50 percent likely to be realized upon ultimate settlement with the related tax authority. The Company recognizes interest and penalties related to unrecognized tax benefits within income tax expense. Any accrued interest and penalties are included within the related tax liability. Effective January 1, 2022, we adopted ASU 2019-12 - Simplifying the Accounting for Income Taxes. The adoption of this standard did not impact the Company’s consolidated financial statements or related disclosures.
Comprehensive Loss	Comprehensive Loss Comprehensive loss is defined as a change in equity during a period from transactions and other events and circumstances from non-owner sources. The Company’s comprehensive loss includes unrealized gains and losses from short-term investments.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding for the period, without consideration of potential dilutive securities. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the sum of the weighted-average number of shares of common stock plus the potential dilutive effects of potential dilutive securities outstanding during the period. Potential dilutive securities are excluded from diluted earnings or loss per share if the effect of such inclusion is antidilutive. The Company’s potentially dilutive securities, which include shares from the 2021 Employee Stock Purchase Plan (the “ESPP”) and outstanding stock options and RSUs under the Company’s equity incentive plan, have been excluded from the computation of diluted net loss per share as they would be anti-dilutive to the net loss per share. For the periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to the Company’s net loss position.
Recent Accounting Pronouncements	Recent Accounting Pronouncements There were no significant updates to the recently issued accounting standards for the year ended December 31, 2022. Although there are several other new accounting pronouncements issued or proposed by the FASB, based on the Company’s preliminary assessment, the Company does not believe any of those accounting pronouncements have had or will have a material impact on its financial position or operating results.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2022
Fair Value Measurements
Summary of Financial Assets Measured at Fair Value on Recurring Basis	The following table summarizes financial assets that the Company measured at fair value on a recurring basis, classified in accordance with the fair value hierarchy (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at Reporting Date Using: ​ Level 1 Level 2 Level 3 Total As of December 31, 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 8,528 ​ $ — ​ $ — ​ $ 8,528 Commercial paper ​ ​ — ​ ​ 83,423 ​ ​ — ​ ​ 83,423 U.S. government securities ​ ​ 10,837 ​ ​ — ​ ​ — ​ ​ 10,837 U.S. agency bonds ​ ​ — ​ ​ 22,143 ​ ​ — ​ ​ 22,143 Corporate debt securities ​ ​ — ​ ​ 997 ​ ​ — ​ ​ 997 Total cash equivalents and short-term investments ​ $ 19,365 ​ $ 106,563 ​ $ — ​ $ 125,928 Reported as: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents (includes cash of $4,526) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 61,955 Short-term investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 68,499 Total cash, cash equivalents and short-term investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 130,454 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at Reporting Date Using: ​ Level 1 Level 2 Level 3 Total As of December 31, 2021 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 10,585 ​ $ — ​ $ — ​ $ 10,585 Commercial paper ​ ​ — ​ ​ 84,616 ​ ​ — ​ ​ 84,616 U.S. government securities ​ ​ 27,824 ​ ​ — ​ ​ — ​ ​ 27,824 U.S. agency bonds ​ ​ — ​ ​ 8,531 ​ ​ — ​ ​ 8,531 Corporate debt securities ​ ​ — ​ ​ 8,265 ​ ​ — ​ ​ 8,265 Total cash equivalents and short-term investments ​ $ 38,409 ​ $ 101,412 ​ $ — ​ $ 139,821 Reported as: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents (includes cash of $397) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 24,780 Short-term investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 115,438 Total cash, cash equivalents and short-term investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 140,218 ​

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2022
Investments
Summary of Cash Equivalents and Investments Measured at Fair Value on Recurring Basis	The following table summarizes, by major types of cash equivalents, and investments that are measured at fair value on a recurring basis (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2022 ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Estimated ​ ​ Cost ​ Gains ​ Losses ​ Fair Value Money market funds ​ $ 8,528 ​ $ — ​ $ — ​ $ 8,528 Commercial paper ​ ​ 83,479 ​ ​ 11 ​ ​ (67) ​ ​ 83,423 U.S. government securities ​ ​ 10,910 ​ ​ — ​ ​ (73) ​ ​ 10,837 U.S. agency bonds ​ ​ 22,175 ​ ​ 4 ​ ​ (36) ​ ​ 22,143 Corporate debt securities ​ ​ 1,002 ​ ​ — ​ ​ (5) ​ ​ 997 Cash equivalents and short-term investments ​ $ 126,094 ​ $ 15 ​ $ (181) ​ $ 125,928 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2021 ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Estimated ​ ​ Cost ​ Gains ​ Losses ​ Fair Value Money market funds ​ $ 10,585 ​ $ — ​ $ — ​ $ 10,585 Commercial paper ​ ​ 84,642 ​ ​ 2 ​ ​ (28) ​ ​ 84,616 U.S. government securities ​ ​ 27,870 ​ ​ — ​ ​ (46) ​ ​ 27,824 U.S. agency bonds ​ ​ 8,546 ​ ​ — ​ ​ (15) ​ ​ 8,531 Corporate debt securities ​ ​ 8,267 ​ ​ — ​ ​ (2) ​ ​ 8,265 Cash equivalents and short-term investments ​ $ 139,910 ​ $ 2 ​ $ (91) ​ $ 139,821 ​
Schedule of Contractual Maturities of AFS Securities	The contractual maturities of the Company’s AFS securities were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ 2022 ​ 2021 Due within one year ​ $ 63,595 ​ $ 105,173 Due within one to two years ​ ​ 4,904 ​ ​ 10,265 Total ​ $ 68,499 ​ $ 115,438 ​

Consolidated Balance Sheet De_2

Consolidated Balance Sheet Details (Tables)	12 Months Ended
	Dec. 31, 2022
Consolidated Balance Sheet Details
Schedule of Prepaid and Other Current Assets	Prepaid and other current assets consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ ​ 2022 ​ 2021 Prepaid research ​ $ 1,103 ​ $ 4,329 Prepaid insurance ​ ​ 913 ​ ​ 827 FICA tax credit receivable ​ ​ 571 ​ ​ 452 Other current assets ​ ​ 152 ​ ​ 205 Prepaid other ​ ​ 416 ​ ​ 96 Deposits ​ ​ 19 ​ ​ 19 Prepaid and other current assets ​ $ 3,174 ​ $ 5,928 ​
Schedule of Property and Equipment, Net	Property and equipment, net, consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ ​ 2022 ​ 2021 Furniture and equipment ​ $ 204 ​ $ 204 Leasehold improvements ​ ​ 67 ​ ​ 67 Computer equipment ​ ​ 50 ​ ​ 50 Construction in progress ​ ​ 8 ​ ​ — ​ ​ $ 329 ​ $ 321 Less: accumulated depreciation and amortization expense ​ ​ (236) ​ ​ (156) Property and equipment, net ​ $ 93 ​ $ 165 ​
Schedule of Other Non-Current Assets	Other non-current assets consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ ​ 2022 ​ 2021 Deposits ​ $ 781 ​ $ 75 FICA tax credit receivable ​ ​ 52 ​ ​ 298 Other ​ ​ 368 ​ ​ 70 Other non-current assets ​ $ 1,201 ​ $ 443 ​
Schedule of Other Accrued Liabilities	Other accrued liabilities consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ ​ 2022 ​ 2021 Accrued bonus ​ $ 3,379 ​ $ 1,933 Accrued payroll and related ​ ​ 229 ​ ​ 39 ESPP liability ​ ​ 155 ​ ​ 369 Other ​ ​ 2,661 ​ ​ 3,353 Other accrued liabilities ​ $ 6,424 ​ $ 5,694

Convertible Preferred Stock a_2

Convertible Preferred Stock and Stockholders' Equity (Deficit) (Tables)	12 Months Ended
	Dec. 31, 2022
Summary of Stock Option Activities	A summary of the Company’s stock option activities during the year ended December 31, 2022 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ Weighted- ​ ​ ​ ​ ​ ​ Average ​ Average ​ Aggregate ​ ​ ​ ​ Exercise ​ Remaining ​ Intrinsic ​ ​ ​ ​ Price Per ​ Contract Term ​ Value ​ ​ Total Options ​ Share ​ (in years) ​ (in millions) Outstanding as of December 31, 2021 ​ 1,734,696 ​ $ 8.50 ​ 8.8 ​ $ 7.6 Granted ​ 1,197,328 ​ $ 7.99 ​ ​ ​ ​ ​ Exercised ​ (40,220) ​ $ 4.20 ​ ​ ​ ​ ​ Forfeited or cancelled ​ (298,043) ​ $ 10.72 ​ ​ ​ ​ ​ Outstanding as of December 31, 2022 ​ 2,593,761 ​ $ 8.08 ​ 8.2 ​ $ 5.3 Vested and expected to vest as of December 31, 2022 ​ 2,593,761 ​ $ 8.08 ​ 8.2 ​ $ 5.3 Vested and exercisable as of December 31, 2022 ​ 988,166 ​ $ 6.86 ​ 7.1 ​ $ 3.0 ​
Summary of Stock-Based Compensation Expense Recognized	The Company recognized stock-based compensation expense as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2022 2021 Research and development ​ $ 3,782 ​ $ 2,486 General and administrative ​ ​ 1,073 ​ ​ 606 Total stock-based compensation expense ​ $ 4,855 ​ $ 3,092 ​
Weighted-Average Assumptions Used in Black-Scholes Option Pricing Model to Determine Fair Value of Stock Option Grants	The weighted-average assumptions used in the Black-Scholes option pricing model to determine the fair value of the stock option grants were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2022 2021 Risk-free interest rate ​ ​ 1.6% - 4.3% ​ ​ 0.8% - 1.3% Expected volatility ​ ​ 88.1% - 112.1% ​ ​ 113.2% - 118.7% Expected term (in years) ​ ​ 5.3 - 6.1 ​ ​ 5.0 – 6.1 Expected dividend yield ​ ​ 0% ​ ​ 0% ​
Schedule of Common Stock Reserved for Future Issuance	Common stock reserved for future issuance consist of the following: ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ 2022 2021 Stock options ​ 2,593,761 ​ 1,734,696 Restricted stock units ​ 8,945 ​ — Reserved for future equity award grants ​ 3,084,732 ​ 2,933,930 Reserved for future ESPP issuances ​ 466,585 ​ 259,689 Common stock reserved for future issuance ​ 6,154,023 ​ 4,928,315
Restricted Stock Units (RSU)
Summary of Restricted Stock Units Activities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ Aggregate ​ ​ Total ​ Average ​ Intrinsic ​ ​ Restricted ​ Grant Date ​ Value ​ ​ Stock Units ​ Fair Values ​ (in millions) Outstanding as of December 31, 2021 ​ — ​ $ — ​ $ — Granted ​ 9,289 ​ $ 6.25 ​ ​ ​ Vested ​ — ​ $ — ​ ​ ​ Forfeited or cancelled ​ (344) ​ $ 6.25 ​ ​ ​ Outstanding as of December 31, 2022 ​ 8,945 ​ $ 6.25 ​ $ 0.1 ​
2021 Employee Share Purchase Plan
Weighted-Average Assumptions Used in Black-Scholes Option Pricing Model to Determine Fair Value of Stock Option Grants	The weighted average assumptions used in the Black-Scholes option pricing model to estimate the fair value of purchase rights granted under the ESPP were as follows: ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2022 ​ 2021 Risk-free interest rate ​ 0.2% ​ 0.1% Expected volatility ​ 139.6% ​ 127.8% Expected term (in years) ​ 2.2 ​ 1.4 Expected dividend yield ​ 0% ​ 0% ​

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies.
Schedule of Future Minimum Lease Payments Required under Operating Lease	The future minimum lease payments required under the operating lease are summarized as follows (in thousands): ​ ​ ​ ​ ​ As of December 31, 2022 2023 ​ $ 171 2024 ​ ​ 129 2025 ​ ​ — Total minimum lease payments ​ $ 300 Less: amount representing interest ​ ​ (23) Present value of operating lease liabilities ​ $ 277 Operating lease liabilities, current ​ ​ 164 Operating lease liabilities, non-current ​ ​ 113 Total operating lease liabilities ​ $ 277 ​ ​ ​ ​ Weighted-average remaining lease term (in years) ​ ​ 1.7 Weighted-average incremental borrowing rate ​ ​ 10.0% ​
Schedule of operating lease liability not yet commenced maturity	In addition to what is included in the table above, the future minimum lease payments for the operating lease not yet commenced are summarized as follows (in thousands): ​ ​ ​ ​ ​ As of December 31, 2022 2023 ​ $ 144 2024 ​ ​ 158 2025 ​ ​ — Total minimum lease payments ​ $ 302 ​
Summary of Lease Costs and Cash Payments	The table below summarizes the Company’s lease costs and cash payments in connection with operating lease obligations (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2022 ​ 2021 2020 Total operating lease expense $ 160 ​ $ 160 ​ $ 130 Operating cash flows used for operating lease ​ $ 167 ​ $ 162 ​ $ 130 ​

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2022
Income Taxes
Components of Provision for Income Taxes	The provision for income taxes is comprised of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2022 2021 Current: ​ ​ ​ ​ ​ ​ State $ 3 ​ $ 2 Provision for income taxes ​ $ 3 ​ $ 2 ​
Computation of Provision for Income Taxes by Applying Federal Statutory Income Tax Rate to Income Before Taxes	The provision for income taxes differs from the amount computed by applying the federal statutory income tax rate to income before taxes as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2022 2021 Federal tax benefit at statutory rate ​ $ (15,901) ​ $ (10,792) State taxes ​ ​ (6,867) ​ ​ 604 Non-deductible expenses ​ ​ 539 ​ ​ 490 R&D credits ​ ​ (4,807) ​ ​ (2,177) Change in valuation allowance ​ ​ 31,449 ​ ​ 11,870 Return-to-provision adjustment ​ ​ (4,341) ​ ​ — Other ​ ​ (69) ​ ​ 7 Provision for income taxes ​ $ 3 ​ $ 2 ​
Components of Deferred Income Tax Assets and Liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ 2022 2021 Deferred tax assets: ​ ​ ​ ​ ​ Accrued expenses and other ​ $ 1,045 $ 407 Fixed assets ​ ​ 19 ​ ​ 10 Intangibles ​ ​ 2,915 ​ ​ 2,378 Net operating losses ​ ​ 29,151 ​ ​ 16,993 R&D and Orphan Drug credits ​ ​ 8,384 ​ ​ 2,615 Section 174 capitalization ​ ​ 11,509 ​ ​ — Stock-based compensation ​ ​ 1,100 ​ ​ 287 Lease liability ​ ​ 80 ​ ​ 87 Other ​ ​ 18 ​ ​ 2 Total deferred tax assets ​ $ 54,221 ​ $ 22,779 Valuation allowance ​ ​ (54,146) ​ ​ (22,698) Total net deferred tax assets ​ $ 75 ​ $ 81 Deferred tax liabilities: ​ ​ ​ ​ ​ ​ Right-of-use asset ​ $ (75) ​ ​ (81) Total deferred tax liabilities ​ $ (75) ​ $ (81) Net deferred tax assets ​ $ — ​ $ — ​
Schedule of Federal and State Net Operating Loss Carryforwards	The following table sets forth the Company’s federal and state net operating loss and R&D credits carryforwards as of December 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ Amount Expiration Years Net operating losses, Federal—pre TCJA $ 159 ​ 2037 Net operating losses, Federal—post TCJA ​ $ 84,927 ​ N/A Net operating losses, state ​ $ 127,790 ​ 2031-2042 R&D and Orphan Drug credits, Federal ​ $ 10,666 ​ 2039-2042 R&D credits, California ​ $ 1,739 ​ N/A ​
Changes in Gross Unrecognized Tax Benefits	The following table reflects changes in the gross unrecognized tax benefits (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2022 2021 Balance at beginning of year $ 1,442 $ 402 Additions based on tax positions related to current year ​ ​ 2,167 ​ ​ 1,040 Additions to tax position of prior years ​ ​ 432 ​ ​ — Reductions to tax position of prior years ​ ​ (19) ​ ​ — Balance at end of year ​ $ 4,022 ​ $ 1,442 ​

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2022
Net Loss Per Share
Schedule of Computation of Basic and Diluted Net Loss per Share	The following tables summarize the computation of the basic and diluted net loss per share (in thousands, except share and per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2022 2021 Numerator: ​ ​ ​ ​ ​ ​ Net loss $ (75,724) $ (51,394) Denominator: ​ ​ ​ ​ ​ ​ Weighted-average shares of common stock outstanding, basic and diluted ​ ​ 27,985,446 ​ ​ 19,405,833 Weighted-average shares used to compute net loss per share, basic and diluted ​ ​ 27,985,446 ​ ​ 19,405,833 Net loss per share, basic and diluted ​ $ (2.71) ​ $ (2.65) ​
Schedule of Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss per Share	The following table sets forth the outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share because their inclusion would be anti-dilutive: ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ 2022 2021 Stock options ​ 2,593,761 ​ 1,734,696 Restricted stock units ​ 8,945 ​ — ESPP shares ​ 43,757 ​ 85,031 Total ​ 2,646,463 ​ 1,819,727

Organization and Nature of Op_2

Organization and Nature of Operations (Details) $ / shares in Units, $ in Thousands				1 Months Ended	12 Months Ended
	Nov. 15, 2022 shares	May 11, 2021 shares	Apr. 27, 2021 $ / shares shares	Nov. 30, 2022 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) segment shares	Dec. 31, 2021 USD ($) shares
Organization And Nature Of Operations [Line Items]
Entity incorporation date					Apr. 30, 2017
Number of operating segments | segment					1
Proceeds from issuance of common stock | $				$ 52,900	$ 56,647
Convertible preferred stock, Shares outstanding					0	0
Offering price per share | $ / shares				$ 5.83
Non-voting Common Stock
Organization And Nature Of Operations [Line Items]
Conversion of convertible preferred stock			7,928,501
Conversion of convertible preferred stock to common stock, shares			7,727,470
Common stock and non-voting common stock
Organization And Nature Of Operations [Line Items]
Number of shares issued and sold				8,576,330
IPO and Over Allotment Option
Organization And Nature Of Operations [Line Items]
Proceeds from issuance of common stock | $						$ 121,500
Common Stock
Organization And Nature Of Operations [Line Items]
Number of shares issued and sold						7,845,011
Conversion of convertible preferred stock to common stock, shares						15,069,330
Common Stock | IPO
Organization And Nature Of Operations [Line Items]
Number of shares issued and sold			7,352,941
Public offering price per share | $ / shares			$ 17
Common Stock | Underwriters Option
Organization And Nature Of Operations [Line Items]
Number of shares issued and sold	1,140,068	492,070

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Details) - USD ($)	12 Months Ended	68 Months Ended
	Dec. 31, 2022	Dec. 31, 2022
Summary Of Significant Accounting Policies [Line Items]
Impairment losses on long-lived assets		$ 0
Minimum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets	2 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets	3 years

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Fair Value Measurements
Assets transfer, Level 1 to 2	$ 0	$ 0
Assets transfer, Level 2 to 1	0	0
Assets transfer, out of Level 3	0	0
Assets transfer, into Level 3	0	0
Liabilities transfer, Level 1 to 2	0	0
Liabilities transfer, Level 2 to 1	0	0
Liabilities transfer, into of Level 3	0	0
Liabilities transfer, out of Level 3	0	0
Financial liabilities	$ 0	$ 0

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Financial Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	$ 68,499	$ 115,438
Fair Value on Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and short-term investments	125,928	139,821
Cash and cash equivalents (includes cash)	61,955	24,780
Short-term investments	68,499	115,438
Total cash, cash equivalents and short-term investments	130,454	140,218
Fair Value on Recurring Basis | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and short-term investments	19,365	38,409
Fair Value on Recurring Basis | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and short-term investments	106,563	101,412
Fair Value on Recurring Basis | Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and short-term investments	8,528	10,585
Fair Value on Recurring Basis | Money Market Funds | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and short-term investments	8,528	10,585
Fair Value on Recurring Basis | Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and short-term investments	83,423	84,616
Fair Value on Recurring Basis | Commercial Paper | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and short-term investments	83,423	84,616
Fair Value on Recurring Basis | U.S. Government Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and short-term investments	10,837	27,824
Fair Value on Recurring Basis | U.S. Government Securities | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and short-term investments	10,837	27,824
Fair Value on Recurring Basis | U.S. Agency Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and short-term investments	22,143	8,531
Fair Value on Recurring Basis | U.S. Agency Bonds | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and short-term investments	22,143	8,531
Fair Value on Recurring Basis | Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and short-term investments	997	8,265
Fair Value on Recurring Basis | Corporate Debt Securities | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents and short-term investments	$ 997	$ 8,265

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of Financial Assets Measured at Fair Value on Recurring Basis - Additional Information (Details) - Fair Value on Recurring Basis - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents (includes cash)	$ 61,955	$ 24,780
Cash
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents (includes cash)	$ 4,526	$ 397

Investments - Summary of Cash E

Investments - Summary of Cash Equivalents and Investments Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Cash Cash Equivalents And Investments [Line Items]
Investments, estimated fair value	$ 68,499	$ 115,438
Fair Value on Recurring Basis
Cash Cash Equivalents And Investments [Line Items]
Cash equivalents and short-term investments, amortized cost	126,094	139,910
Cash equivalents and short-term investments, unrealized gains	15	2
Cash equivalents and short-term investments, unrealized losses	(181)	(91)
Cash equivalents and short-term investments, estimated fair value	125,928	139,821
Fair Value on Recurring Basis | Money Market Funds
Cash Cash Equivalents And Investments [Line Items]
Cash equivalents, amortized cost	8,528	10,585
Cash equivalents, estimated fair value	8,528	10,585
Fair Value on Recurring Basis | Commercial Paper
Cash Cash Equivalents And Investments [Line Items]
Investments, amortized cost	83,479	84,642
Investments, unrealized gains	11	2
Investments, unrealized losses	(67)	(28)
Investments, estimated fair value	83,423	84,616
Fair Value on Recurring Basis | U.S. Government Securities
Cash Cash Equivalents And Investments [Line Items]
Investments, amortized cost	10,910	27,870
Investments, unrealized losses	(73)	(46)
Investments, estimated fair value	10,837	27,824
Fair Value on Recurring Basis | U.S. Agency Bonds
Cash Cash Equivalents And Investments [Line Items]
Investments, amortized cost	22,175	8,546
Investments, unrealized gains	4
Investments, unrealized losses	(36)	(15)
Investments, estimated fair value	22,143	8,531
Fair Value on Recurring Basis | Corporate Debt Securities
Cash Cash Equivalents And Investments [Line Items]
Investments, amortized cost	1,002	8,267
Investments, unrealized losses	(5)	(2)
Investments, estimated fair value	$ 997	$ 8,265

Investments - Schedule of Contr

Investments - Schedule of Contractual Maturities of AFS Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Investments
Due within one year	$ 63,595	$ 105,173
Due within one to two years	4,904	10,265
Total	$ 68,499	$ 115,438

Investments - Narrative (Detail

Investments - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Investments
Investments, realized gains or losses	$ 0	$ 0
Marketable securities, gross unrealized loss position	85,900,000
Marketable securities, continuous unrealized loss position, greater than 12 months	0
Marketable securities, continuous unrealized loss position, less than 12 months	$ 53,600,000

Consolidated Balance Sheet De_3

Consolidated Balance Sheet Details - Schedule of Prepaid and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Consolidated Balance Sheet Details
Prepaid research	$ 1,103	$ 4,329
Prepaid insurance	913	827
FICA tax credit receivable	571	452
Other current assets	152	205
Prepaid other	416	96
Deposits	19	19
Prepaid and other current assets	$ 3,174	$ 5,928

Consolidated Balance Sheet De_4

Consolidated Balance Sheet Details - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 329	$ 321
Less: accumulated depreciation and amortization expense	(236)	(156)
Property and equipment, net	93	165
Furniture and Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	204	204
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	67	67
Computer Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	50	$ 50
Construction in Progress
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 8

Consolidated Balance Sheet De_5

Consolidated Balance Sheet Details - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Consolidated Balance Sheet Details
Depreciation expense	$ 0.1	$ 0.1

Consolidated Balance Sheet De_6

Consolidated Balance Sheet Details - Schedule of Other Non-Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Consolidated Balance Sheet Details
Deposits	$ 781	$ 75
FICA tax credit receivable	52	298
Other	368	70
Other non-current assets	$ 1,201	$ 443

Consolidated Balance Sheet De_7

Consolidated Balance Sheet Details - Schedule of Other Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Consolidated Balance Sheet Details
Accrued bonus	$ 3,379	$ 1,933
Accrued payroll and related	229	39
ESPP liability	155	369
Other	2,661	3,353
Other accrued liabilities	$ 6,424	$ 5,694

Convertible Preferred Stock a_3

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Narrative (Details)			1 Months Ended				12 Months Ended
	Apr. 27, 2021 shares	Apr. 15, 2021 shares	Nov. 30, 2022 USD ($)	Sep. 30, 2020 USD ($) shares	Dec. 31, 2018 USD ($) shares	Apr. 30, 2018 USD ($) shares	Dec. 31, 2022 USD ($) Vote $ / shares shares	Dec. 31, 2021 $ / shares shares	Jan. 01, 2023 shares	Apr. 30, 2021 $ / shares shares	Dec. 31, 2020 $ / shares shares
Class Of Stock [Line Items]
Common stock, shares authorized							250,000,000	250,000,000		250,000,000	24,000,000
Common stock, Par value | $ / shares							$ 0.001	$ 0.001		$ 0.001	$ 0.001
Preferred Stock, shares authorized							10,000,000	10,000,000			16,273,406
Preferred stock, par value | $ / shares							$ 0.001	$ 0.001			$ 0.001
Common stock, voting rights							Each holder of Voting Common Stock, as such, shall be entitled to one vote for each share of Voting Common Stock held
Number of vote per common stock | Vote							1
Convertible preferred stock, conversion terms							Each share of Series A and Series B convertible preferred stock will be automatically converted into common stock immediately upon (i) the closing of a firm commitment underwritten IPO resulting in at least $50.0 million of gross proceeds to the Company or (ii) the receipt by the Company of a written request for automatic conversion from the holders of a majority of the outstanding shares of Series A and Series B convertible preferred stock.
Potential commitment amount from gross proceeds of underwritten initial public offering | $							$ 50,000,000
Convertible preferred stock, voting rights							The holders of the Series A and Series B convertible preferred stock were entitled to one vote for each share of common stock into which such shares of Series A and Series B convertible preferred stock could then be converted; and with respect to such vote, such holders shall have full voting rights and powers equal to the voting rights and powers of the holders of the common stock.
Convertible preferred stock, Shares outstanding							0	0
Common stock, reserved for future issuance							6,154,023	4,928,315
Weighted-average grant date fair values of option grants | $ / shares							$ 6.61	$ 12.14
Weighted-average grant date fair values of options forfeited | $ / shares							$ 9.35	$ 6.08
Maximum contribution made by employees compensation		15%
Aggregate cash proceeds from issued shares of common stock | $			$ 52,900,000				$ 56,647,000
Common Stock Options
Class Of Stock [Line Items]
Common stock, reserved for future issuance							2,593,761	1,734,696
Stock options and restricted stock units
Class Of Stock [Line Items]
Unrecognized compensation cost related to outstanding options | $							$ 10,700,000
Cost not yet recognized, period for Recognition							2 years 7 months 6 days
2018 Stock Issuance Plan
Class Of Stock [Line Items]
Stock options granted		0
2018 Stock Issuance Plan | Common Stock Options
Class Of Stock [Line Items]
Stock options, grant equity-based awards issued							1,722
2021 Equity Incentive Plan
Class Of Stock [Line Items]
Stock options granted							1,197,328
Percentage of outstanding number of shares of common stock		4%
2021 Equity Incentive Plan | Common Stock Options
Class Of Stock [Line Items]
Common stock, reserved for future issuance									1,451,611
2021 Employee Share Purchase Plan
Class Of Stock [Line Items]
Unrecognized compensation cost related to outstanding options | $							$ 100,000
Cost not yet recognized, period for Recognition							6 months
Employee Stock Purchase Plan
Class Of Stock [Line Items]
Common stock, reserved for future issuance							57,862		362,902
Percentage of outstanding number of shares of common stock		1%
Purchase of common stock at discount from market price, offering date		85%
Stock plan offering period		24 months
Aggregate cash proceeds from issued shares of common stock | $							$ 400,000
Maximum | 2021 Equity Incentive Plan | Common Stock Options
Class Of Stock [Line Items]
Common stock, reserved for future issuance		3,246,120
Maximum | 2021 Employee Share Purchase Plan
Class Of Stock [Line Items]
Shares authorized for issuance		259,689
IPO
Class Of Stock [Line Items]
Common stock, shares authorized										260,000,000
Series A Convertible Preferred Stock
Class Of Stock [Line Items]
Convertible preferred stock, Shares authorized											3,731,208
Convertible preferred stock, Shares issued					1,390,788	2,098,269
Convertible preferred stock for aggregate purchase price | $					$ 7,300,000	$ 11,000,000
Dividends, preferred stock | $							$ 0
Number of vote per convertible preferred stock upon conversion into common stock | Vote							1
Conversion of convertible preferred stock								3,731,208
Convertible preferred stock, Shares outstanding							0				3,731,208
Series B Convertible Preferred Stock
Class Of Stock [Line Items]
Convertible preferred stock, Shares authorized											12,542,198
Convertible preferred stock, Shares issued				10,636,510
Convertible preferred stock for aggregate purchase price | $				$ 63,200,000
Dividends, preferred stock | $							$ 0
Number of vote per convertible preferred stock upon conversion into common stock | Vote							1
Conversion of convertible preferred stock								12,542,198
Convertible preferred stock, Shares outstanding							0				12,542,198
Undesignated Preferred Stock
Class Of Stock [Line Items]
Preferred Stock, shares authorized										10,000,000
Preferred stock, par value | $ / shares										$ 0.001
Common Stock
Class Of Stock [Line Items]
Common stock, shares authorized										200,000,000
Conversion of convertible preferred stock	8,344,905
Conversion of convertible preferred stock to common stock, shares	7,341,860
Non-voting Common Stock
Class Of Stock [Line Items]
Common stock, shares authorized										50,000,000
Common stock, conversion terms							Each holder of shares of Non-Voting Common Stock shall have the right to convert each share of Non-Voting Common Stock held by such holder into one share (subject to appropriate adjustment in the event of any stock dividend, stock split, reverse stock split, combination or other similar recapitalization with respect to the Voting Common Stock) of Voting Common Stock at such holder’s election by providing written notice to the Company
Common stock, beneficial ownership limitation percentage							9.99%
Written notice period to increase common stock beneficial ownership limitation							61 days
Conversion of convertible preferred stock	7,928,501
Conversion of convertible preferred stock to common stock, shares	7,727,470
Non-voting Common Stock | Maximum
Class Of Stock [Line Items]
Common stock, beneficial ownership limitation percentage							19.99%

Convertible Preferred Stock a_4

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Summary of Stock Option Activities (Details) - 2021 Equity Incentive Plan - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Total Options
Total Options Outstanding, Beginning balance	1,734,696
Stock options granted	1,197,328
Total Options, Exercised	(40,220)
Total Options Forfeited or cancelled	(298,043)
Total Options Outstanding, Ending balance	2,593,761	1,734,696
Total Options, Vested and expected to vest as of December 31, 2022	2,593,761
Total Options, Vested and exercisable as of December 31, 2022	988,166
Weighted-Average Exercise Price Per Share
Weighted-Average Exercise Price Per Share	$ 8.50
Weighted-Average Exercise Price Per Share, Granted	7.99
Weighted-Average Exercise Price Per Share, Exercised	4.20
Weighted-Average Exercise Price Per Share, Forfeited or cancelled	10.72
Weighted-Average Exercise Price Per Share	8.08	$ 8.50
Weighted-Average Exercise Price Per Share, Vested and expected to vest	8.08
Weighted-Average Exercise Price Per Share, Vested and exercisable	$ 6.86
Weighted-Average Remaining Contract Term
Weighted-Average Remaining Contract Term	8 years 2 months 12 days	8 years 9 months 18 days
Weighted-Average Remaining Contract Term, Vested and expected to vest	8 years 2 months 12 days
Weighted-Average Remaining Contract Term, Vested and exercisable	7 years 1 month 6 days
Aggregate Intrinsic Value
Aggregate Intrinsic Value, Outstanding	$ 5.3	$ 7.6
Aggregate Intrinsic Value, Vested and expected to vest	5.3
Aggregate Intrinsic Value, Vested and exercisable	$ 3

Convertible Preferred Stock a_5

Convertible Preferred Stock and Stockholders' Equity (Deficit) - RSU Activities (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($) $ / shares shares
Total Restricted Stock Units
Total Restricted Stock Units, Vested	0
Restricted Stock Units (RSU)
Total Restricted Stock Units
Total Restricted Stock Units, Granted	9,289
Total Restricted Stock Units, Forfeited or cancelled	(344)
Total Restricted Stock Units Outstanding, Ending balance	8,945
Weighted-Average Grant Date Fair Values
Weighted-Average Grant Date Fair Values, Granted | $ / shares	$ 6.25
Weighted-Average Grant Date Fair Values, Forfeited or cancelled | $ / shares	6.25
Weighted-Average Grant Date Fair Values Outstanding, Ending balance | $ / shares	$ 6.25
Aggregate Intrinsic Value
Aggregate Intrinsic Value, Outstanding | $	$ 0.1

Convertible Preferred Stock a_6

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Summary of Stock-Based Compensation Expense Recognized (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 4,855	$ 3,092
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	3,782	2,486
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,073	$ 606

Convertible Preferred Stock a_7

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Weighted-Average Assumptions Used in Black-Scholes Option Pricing Model to Determine Fair Value of Stock Option Grants (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, minimum	1.60%	0.80%
Risk-free interest rate, maximum	4.30%	1.30%
Expected volatility, minimum	88.10%	113.20%
Expected volatility, maximum	112.10%	118.70%
Expected dividend yield	0%	0%
Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	0.20%	0.10%
Expected volatility	139.60%	127.80%
Expected term (in years)	2 years 2 months 12 days	1 year 4 months 24 days
Expected dividend yield	0%	0%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	5 years 3 months 18 days	5 years
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 years 1 month 6 days	6 years 1 month 6 days

Convertible Preferred Stock a_8

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Schedule of Common Stock Reserved for Future Issuance (Details) - shares	Dec. 31, 2022	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	6,154,023	4,928,315
Stock options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	2,593,761	1,734,696
Restricted Stock Units (RSU)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	8,945
Reserved for future equity award grants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	3,084,732	2,933,930
Reserved for future ESPP issuances
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	466,585	259,689

License Agreements (Details)

License Agreements (Details)		1 Months Ended	2 Months Ended	12 Months Ended
	Mar. 03, 2022 USD ($) installment	Sep. 30, 2020 USD ($)	Mar. 09, 2023 USD ($)	Dec. 31, 2022 USD ($) item	Dec. 31, 2021 USD ($)	Sep. 30, 2022 USD ($)	Jun. 29, 2022 USD ($)	Jun. 28, 2022 USD ($)	Sep. 30, 2021 USD ($)
License Agreements [Line Items]
Accrued milestone payment							$ 2,000,000	$ 3,000,000
Research and development expense, reduction				$ 1,000,000
Daiichi Sankyo License Agreement
License Agreements [Line Items]
License agreement, effective date				Sep. 02, 2020
Upfront payment		$ 5,000,000
Sublicensable rights, number of families of patents | item				7
Number of clinical trials | item				3
Reimbursement total	$ 2,000,000
Number of reimbursement installments | installment	4
Reimbursement paid in each installment	$ 500,000
Reimbursement installment paid				$ 1,500,000
Period of installment maturity date				Dec. 31, 2022
Other clinical trials payments				$ 100,000	$ 200,000
Maximum future milestone payments				223,500,000
Clinical trials reimbursement expense				2,000,000
Milestone fees						$ 0			$ 5,500,000
Milestone payments									$ 2,500,000
Accrued milestone payment					3,000,000
Royalty payments				$ 0
Royalty obligation termination description				The royalty obligation terminates on a country-by-country and on a product-by-product basis on the later of: (i) loss of all market exclusivity for such Product in such country, (ii) the last-to-expire patent that covers the Licensed Compound or the Product in such country and (iii) twelve years from launch of the first Product sold by the Company in such country
Cure period				90 days
Agreement termination written notice period				6 months
Daiichi Sankyo License Agreement | Subsequent Event
License Agreements [Line Items]
Reimbursement installment paid			$ 500,000
Drexel License Agreement | Drexel University
License Agreements [Line Items]
Payments for license agreements				$ 53,118	$ 34,387

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) $ in Millions	1 Months Ended
	Jun. 30, 2020	Sep. 30, 2018	Oct. 31, 2022 USD ($) ft²
Commitments and Contingencies.
Initial term of operating lease		5 years 3 months
Operating lease commencement month and year		2019-01
Operating lease expiration month and year		2024-03
Increase in annual base rent percentage	3%	2%
Increase in annual base rent month and day of each year	--02-01	--03-01
Rent relief period	3 months
Operating lease extended expiration month and year	2024-09
Future lease payments over the life of the lease are estimated to increase | $			$ 0.3
Lease agreement to expand the leased premises | ft²			3,880

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Future Minimum Lease Payments Required under Operating Lease (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Commitments and Contingencies.
2023	$ 171
2024	129
Total minimum lease payments	300
Less: amount representing interest	(23)
Present value of operating lease liabilities	277
Operating lease liabilities, current	164	$ 160
Operating lease liabilities, non-current	$ 113	$ 252
Weighted-average remaining lease term (in years)	1 year 8 months 12 days
Weighted-average incremental borrowing rate	10%

Commitments and Contingencies_3

Commitments and Contingencies -Future Minimum Lease Payments For The Operating Lease Not Yet Commenced (Details) $ in Thousands	Dec. 31, 2022 USD ($)
Commitments and Contingencies.
2023	$ 144
2024	158
Total minimum lease payments	$ 302

Commitments and Contingencies_4

Commitments and Contingencies - Summary of Lease Costs and Cash Payments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Commitments and Contingencies.
Total operating lease expense	$ 160	$ 160	$ 130
Operating cash flows used for operating lease	$ 167	$ 162	$ 130

Employee Benefits (Details)

Employee Benefits (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Employee Benefits
Defined contribution plan, employer matching contribution amount	$ 541,471	$ 233,831

Income Taxes - Components of Pr

Income Taxes - Components of Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Current:
State	$ 3	$ 2
Provision for income taxes	$ 3	$ 2

Income Taxes - Computation of P

Income Taxes - Computation of Provision for Income Taxes by Applying Federal Statutory Income Tax Rate to Income Before Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Taxes
Federal tax benefit at statutory rate	$ (15,901)	$ (10,792)
State taxes	(6,867)	604
Non-deductible expenses	539	490
R&D credits	(4,807)	(2,177)
Change in valuation allowance	31,449	11,870
Return-to-provision adjustment	(4,341)
Other	(69)	7
Provision for income taxes	$ 3	$ 2

Income Taxes - Components of De

Income Taxes - Components of Deferred Income Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Components Of Deferred Tax Assets And Liabilities [Abstract]
Accrued expenses and other	$ 1,045	$ 407
Fixed assets	19	10
Intangibles	2,915	2,378
Net operating losses	29,151	16,993
R&D and Orphan Drug credits	8,384	2,615
Section 174 capitalization	11,509
Stock-based compensation	1,100	287
Lease liability	80	87
Other	18	2
Total deferred tax assets	54,221	22,779
Valuation allowance	(54,146)	(22,698)
Total net deferred tax assets	75	81
Right-of-use asset	(75)	(81)
Total deferred tax liabilities	(75)	(81)
Net deferred tax assets

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating Loss Carryforwards [Line Items]
Valuation allowance	$ 54,146,000	$ 22,698,000
Valuation allowance increase	31,400,000	11,900,000
Unrecognized tax benefits	4,022,000	1,442,000	$ 402,000
Interest or penalties	0	$ 0
California Franchise Tax Board
Operating Loss Carryforwards [Line Items]
Net operating losses, provision adjustment	$ 3,400,000

Income Taxes - Schedule of Fede

Income Taxes - Schedule of Federal and State Net Operating Loss Carryforwards (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)
Federal-Pre TCJA
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards, Amount	$ 159
Expiration Years	2037
Federal-Post TCJA
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards, Amount	$ 84,927
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards, Amount	$ 127,790
State | Minimum
Operating Loss Carryforwards [Line Items]
Expiration Years	2031
State | Maximum
Operating Loss Carryforwards [Line Items]
Expiration Years	2042
R&D and Orphan Drug Credits, Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards, Amount	$ 10,666
R&D and Orphan Drug Credits, Federal | Minimum
Operating Loss Carryforwards [Line Items]
Expiration Years	2039
R&D and Orphan Drug Credits, Federal | Maximum
Operating Loss Carryforwards [Line Items]
Expiration Years	2042
R&D Credits, California
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards, Amount	$ 1,739

Income Taxes - Changes in Gross

Income Taxes - Changes in Gross Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Taxes
Balance at beginning of year	$ 1,442	$ 402
Additions based on tax positions related to current year	2,167	1,040
Additions to tax position of prior years	432
Reductions to tax position of prior years	(19)
Balance at end of year	$ 4,022	$ 1,442

Net Loss Per Share - Schedule o

Net Loss Per Share - Schedule of Computation of Basic and Diluted Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Numerator:
Net loss	$ (75,724)	$ (51,394)
Denominator:
Weighted-average shares of common stock outstanding, basic	27,985,446	19,405,833
Weighted-average shares of common stock outstanding, diluted	27,985,446	19,405,833
Weighted-average shares used to compute net loss per share, basic	27,985,446	19,405,833
Weighted-average shares used to compute net loss per share, diluted	27,985,446	19,405,833
Net loss per share, basic	$ (2.71)	$ (2.65)
Net loss per share, diluted	$ (2.71)	$ (2.65)

Net Loss Per Share - Schedule_2

Net Loss Per Share - Schedule of Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss per Share (Details) - shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities	2,646,463	1,819,727
Stock options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities	2,593,761	1,734,696
Restricted stock units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities	8,945
ESPP shares
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities	43,757	85,031

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ in Thousands	1 Months Ended		2 Months Ended	12 Months Ended
	Feb. 28, 2023	Nov. 30, 2022	Feb. 28, 2023	Dec. 31, 2022	Dec. 31, 2021
Subsequent Event [Line Items]
Common stock, shares outstanding				36,290,292	26,475,812
Proceeds from issuance of common stock		$ 52,900		$ 56,647
Subsequent Event [Member] | ATM Facility
Subsequent Event [Line Items]
Proceeds from issuance of common stock			$ 300
Number of shares issued and sold			32,000
Subsequent Event [Member] | Nonvoting Common Stock
Subsequent Event [Line Items]
Conversion of common stock	500,000
Common stock, shares outstanding	9,842,720		9,842,720