0000950170-24-125476 | 10-Q | XBRL Viewer

Asset Acquisition	9 Months Ended
Sep. 30, 2024
Asset Acquisition [Abstract]
Asset Acquisition	7. Asset Acquisition In December 2020, the Company entered into the Agreement and Plan of Merger and Reorganization (the “Myst Merger Agreement”), by and among the Company, Flatiron Merger Sub I, Inc. (“Merger Sub”), Flatiron Merger Sub II, LLC (“Merger LLC”), a direct, wholly-owned subsidiary of the Company, Myst, and Timothy Langer, the sole common stockholder of Myst (“Langer”). Pursuant to the Myst Merger Agreement, the business combination (the “Merger”) was effected in two steps. The first step was the merger of Merger Sub with and into Myst. The second step was the merger of Myst with and into Merger LLC. The Merger closed on December 14, 2020, and the effective date of the Merger was January 20, 2021. As a result of the Merger, the separate existences of Merger Sub and Myst ceased, and Merger LLC became the Company’s wholly-owned subsidiary. Pursuant to the Myst Merger Agreement, on December 15, 2020, the Company paid the former equity holders of Myst, (the “Myst Holders”), a one-time up-front payment of $9.0 million in cash. The Company paid an additional cash consideration of $1.0 million to the Myst Holders on June 14, 2022. The Company also issued Langer up to 725,920 shares of the Company’s common stock. Of these shares, 362,960 shares of the Company’s common stock were issued upon the closing of the Merger and the remaining 362,960 shares of the Company’s common stock were held in escrow with 25% vesting in December of each year that Langer remains with the Company. As of September 30, 2024, Langer is an advisor to the Company and 272,220 shares of the Company’s common stock have vested and been released from escrow with the remaining 90,740 shares of the Company’s common stock to be released at the end of 2024. This restricted equity grant is accounted for as a compensatory arrangement under ASC Topic 718, Compensation — Stock Compensation (“ASC 718”) as continued service is required under the agreement. In addition, under the Myst Merger Agreement, each Myst Holder is entitled to receive certain payments as consideration based on the achievement by the Company of three predefined milestones. The initial milestone was the closing of an initial public offering, which occurred on July 25, 2023, the second milestone was the first acceptance by the FDA of an IND filed by, on behalf of or for the benefit of the Company, or the Company’s sublicensees for a product being developed by or on behalf of the Company or its sublicensees that is claimed as a product or method of making or using the product by a pending or issued Myst patent claim existing at the time of such acceptance, and the third milestone is the occurrence of the earlier of (i) the commencement of the first registration study for a product being developed by, on behalf of or for the benefit of the Company that is claimed as a product or a method of making or using the product by an issued Myst patent claim existing as of the time of such commencement or (ii) the issuance of a Myst patent claim that claims a product or method of making or using the product then being developed by, on behalf of or for the benefit of the Company, or its sublicensees, that is or was the subject of a registration study that has or had commenced. The milestones are not contingent on one another, and the milestones do not need to be achieved in any specific order. Within 45 days of the achievement of the initial milestone, which occurred on July 25, 2023, the Company is obligated to pay the Myst Holders an aggregate amount equal to $3.0 million. At the Company’s election, the Company may pay this consideration in cash or in shares of the Company’s common stock. Pursuant to a letter agreement dated September 11, 2023 between the Company and the former equityholders of Myst regarding the $3.0 million milestone payment that became due and owing to the Myst Holders, the Company agreed to pay $0.2 million in cash to the former optionholders of Myst on or before September 30, 2023, with the remaining $2.8 million payable to Langer in shares of the Company’s common stock. On September 11, 2023, the Company issued Langer 249,992 shares of the Company’s common stock. Within 45 days of the achievement of the second milestone, the Company is obligated to pay the Myst Holders an aggregate amount equal to $10.0 million. At the Company’s election, the Company may pay this consideration in cash or in shares of the Company’s common stock. In May 2022, this $10.0 million milestone was achieved. The Company elected to pay $5.0 million in the Company’s common stock and $5.0 million in cash. Pursuant to a letter agreement dated July 25, 2022 between the Company and the former equityholders of Myst regarding the $10.0 million milestone payment that became due and owing to the Myst Holders, the Company agreed to pay to the former optionholders of Myst on or before July 28, 2022, $0.6 million in cash, with the remaining $9.4 million payable to Langer as follows: (i) on or before July 28, 2022, $2.2 million in cash, (ii) on or before July 31, 2022, $5.0 million in shares of the Company’s common stock and (iii) on or before January 10, 2023, $2.2 million in cash. On June 8, 2022, the Company issued Langer 212,203 shares of the Company’s common stock to settle the $5.0 million obligation payable in common stock. The Company then paid the Myst Holders $2.8 million in July 2022, with $2.2 million paid to Langer and $0.6 million paid to the remaining Myst Holders, and the remaining $2.2 million was paid to Langer in January 2023. Within 45 days of the achievement of the third milestone, the Company is obligated to pay the Myst Holders an aggregate amount equal to $20.0 million. At the Company’s election, the Company may pay this consideration in cash or in shares of its common stock. The Company accounted for the merger with Myst pursuant to the Myst Merger Agreement as an asset acquisition as substantially all of the value received was concentrated in the acquired in-process research and development of Myst and did not have an alternate future use. The Company recognized a $19.4 million charge to research and development expense at the time of the completion of the asset acquisition during the year ended December 31, 2020. The Company determined that the milestone payments are separate units of account and accounted for the initial milestone as a derivative in accordance with ASC Topic 815, Derivatives and Hedging (“ASC 815”) and the second and third milestones as liabilities in accordance with ASC Topic 480, Distinguishing Liabilities from Equity (“ASC 480”). In connection with the initial public offering, the Company reassessed its initial accounting of the milestone payments and concluded that they should be viewed as one unit of account because the milestone payments are not legally detachable from each other. The milestone payments, as one unit of account, would be classified as a liability in accordance with ASC 480 and measured at fair value, with changes in the fair value recorded in earnings. Regardless of whether the milestone payments are viewed as one unit of account or three units of account, because they are all subject to fair value measurement, the financial reporting effect of the contingent consideration arrangement as one unit of account or three units of account is substantially the same. As a liability under ASC 480, the contingent consideration will continue to be recorded at fair value until settled. The adjustment to the fair value of the contingent consideration of $0.2 million and $0.8 million for the three months ended September 30, 2024 and 2023, respectively and $0.1 million and $1.7 million for the nine months ended September 30, 2024 and 2023, respectively, were included in research and development expense in the Company’s unaudited condensed consolidated statements of operations and comprehensive loss.

Asset Acquisition

9 Months Ended

Sep. 30, 2024

7. Asset Acquisition

In December 2020, the Company entered into the Agreement and Plan of Merger and Reorganization (the “Myst Merger Agreement”), by and among the Company, Flatiron Merger Sub I, Inc. (“Merger Sub”), Flatiron Merger Sub II, LLC (“Merger LLC”), a direct, wholly-owned subsidiary of the Company, Myst, and Timothy Langer, the sole common stockholder of Myst (“Langer”). Pursuant to the Myst Merger Agreement, the business combination (the “Merger”) was effected in two steps. The first step was the merger of Merger Sub with and into Myst. The second step was the merger of Myst with and into Merger LLC. The Merger closed on December 14, 2020, and the effective date of the Merger was January 20, 2021. As a result of the Merger, the separate existences of Merger Sub and Myst ceased, and Merger LLC became the Company’s wholly-owned subsidiary.

Pursuant to the Myst Merger Agreement, on December 15, 2020, the Company paid the former equity holders of Myst, (the “Myst Holders”), a one-time up-front payment of $9.0 million in cash. The Company paid an additional cash consideration of $1.0 million to the Myst Holders on June 14, 2022. The Company also issued Langer up to 725,920 shares of the Company’s common stock. Of these shares, 362,960 shares of the Company’s common stock were issued upon the closing of the Merger and the remaining 362,960 shares of the Company’s common stock were held in escrow with 25% vesting in December of each year that Langer remains with the Company. As of September 30, 2024, Langer is an advisor to the Company and 272,220 shares of the Company’s common stock have vested and been released from escrow with the remaining 90,740 shares of the Company’s common stock to be released at the end of 2024. This restricted equity grant is accounted for as a compensatory arrangement under ASC Topic 718, Compensation — Stock Compensation (“ASC 718”) as continued service is required under the agreement.

In addition, under the Myst Merger Agreement, each Myst Holder is entitled to receive certain payments as consideration based on the achievement by the Company of three predefined milestones. The initial milestone was the closing of an initial public offering, which occurred on July 25, 2023, the second milestone was the first acceptance by the FDA of an IND filed by, on behalf of or for the benefit of the Company, or the Company’s sublicensees for a product being developed by or on behalf of the Company or its sublicensees that is claimed as a product or method of making or using the product by a pending or issued Myst patent claim existing at the time of such acceptance, and the third milestone is the occurrence of the earlier of (i) the commencement of the first registration study for a product being developed by, on behalf of or for the benefit of the Company that is claimed as a product or a method of making or using the product by an issued Myst patent claim existing as of the time of such commencement or (ii) the issuance of a Myst patent claim that claims a product or method of making or using the product then being developed by, on behalf of or for the benefit of the Company, or its sublicensees, that is or was the subject of a registration study that has or had commenced. The milestones are not contingent on one another, and the milestones do not need to be achieved in any specific order.

Within 45 days of the achievement of the initial milestone, which occurred on July 25, 2023, the Company is obligated to pay the Myst Holders an aggregate amount equal to $3.0 million. At the Company’s election, the Company may pay this consideration in cash or in shares of the Company’s common stock. Pursuant to a letter agreement dated September 11, 2023 between the Company and the former equityholders of Myst regarding the $3.0 million milestone payment that became due and owing to the Myst Holders, the Company agreed to pay $0.2 million in cash to the former optionholders of Myst on or before September 30, 2023, with the remaining $2.8 million payable to Langer in shares of the Company’s common stock. On September 11, 2023, the Company issued Langer 249,992 shares of the Company’s common stock.

Within 45 days of the achievement of the second milestone, the Company is obligated to pay the Myst Holders an aggregate amount equal to $10.0 million. At the Company’s election, the Company may pay this consideration in cash or in shares of the Company’s common stock. In May 2022, this $10.0 million milestone was achieved. The Company elected to pay $5.0 million in the Company’s common stock and $5.0 million in cash. Pursuant to a letter agreement dated July 25, 2022 between the Company and the former equityholders of Myst regarding the $10.0 million milestone payment that became due and owing to the Myst Holders, the Company agreed to pay to the former optionholders of Myst on or before July 28, 2022, $0.6 million in cash, with the remaining $9.4 million payable to Langer as follows: (i) on or before July 28, 2022, $2.2 million in cash, (ii) on or before July 31, 2022, $5.0 million in shares of the Company’s common stock and (iii) on or before January 10, 2023, $2.2 million in cash. On June 8, 2022, the Company issued Langer 212,203 shares of the Company’s common stock to settle the $5.0 million obligation payable in common

stock. The Company then paid the Myst Holders $2.8 million in July 2022, with $2.2 million paid to Langer and $0.6 million paid to the remaining Myst Holders, and the remaining $2.2 million was paid to Langer in January 2023.

Within 45 days of the achievement of the third milestone, the Company is obligated to pay the Myst Holders an aggregate amount equal to $20.0 million. At the Company’s election, the Company may pay this consideration in cash or in shares of its common stock.

The Company accounted for the merger with Myst pursuant to the Myst Merger Agreement as an asset acquisition as substantially all of the value received was concentrated in the acquired in-process research and development of Myst and did not have an alternate future use. The Company recognized a $19.4 million charge to research and development expense at the time of the completion of the asset acquisition during the year ended December 31, 2020. The Company determined that the milestone payments are separate units of account and accounted for the initial milestone as a derivative in accordance with ASC Topic 815, Derivatives and Hedging (“ASC 815”) and the second and third milestones as liabilities in accordance with ASC Topic 480, Distinguishing Liabilities from Equity (“ASC 480”). In connection with the initial public offering, the Company reassessed its initial accounting of the milestone payments and concluded that they should be viewed as one unit of account because the milestone payments are not legally detachable from each other. The milestone payments, as one unit of account, would be classified as a liability in accordance with ASC 480 and measured at fair value, with changes in the fair value recorded in earnings. Regardless of whether the milestone payments are viewed as one unit of account or three units of account, because they are all subject to fair value measurement, the financial reporting effect of the contingent consideration arrangement as one unit of account or three units of account is substantially the same. As a liability under ASC 480, the contingent consideration will continue to be recorded at fair value until settled. The adjustment to the fair value of the contingent consideration of $0.2 million and $0.8 million for the three months ended September 30, 2024 and 2023, respectively and $0.1 million and $1.7 million for the nine months ended September 30, 2024 and 2023, respectively, were included in research and development expense in the Company’s unaudited condensed consolidated statements of operations and comprehensive loss.

Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2024
Accounting Policies [Abstract]
Basis of Presentation of Unaudited Condensed Consolidated Financial Information	Basis of Presentation of Unaudited Condensed Consolidated Financial Information The accompanying unaudited condensed consolidated financial statements of the Company have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information and pursuant to the rules and regulations of the SEC. Accordingly, they do not include all the information and footnotes required by GAAP for complete financial statements. However, such interim financial statements reflect all adjustments (consisting solely of normal recurring adjustments), which are, in the opinion of management, necessary for the fair presentation of the Company’s financial position and results of operations. Results shown for interim periods are not necessarily indicative of the results that may be expected for the year ended December 31, 2024 or for any other period. The condensed consolidated balance sheet as of December 31, 2023 was derived from the audited consolidated financial statements. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements, included in the Company’s Annual Report on Form 10-K filed with the SEC on March 22, 2024. Certain prior period amounts reported in the Company’s unaudited condensed consolidated financial statements and accompanying notes have been reclassified to conform to the current period presentation. Any reference in these notes to applicable guidance is meant to refer to the authoritative accounting principles generally accepted in the United States as found in the Accounting Standard Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”).
Principles of Consolidation	Principles of Consolidation The accompanying unaudited condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.
Significant Accounting Policies	Significant Accounting Policies The significant accounting policies used in preparation of these unaudited condensed consolidated financial statements are consistent with those discussed in Note 2 to the audited consolidated financial statements included in the Company’s Annual Report filed on Form 10-K filed with the SEC on March 22, 2024.
Use of Estimates	Use of Estimates The preparation of these unaudited condensed consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the amounts reported in the unaudited condensed consolidated financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to accrued expenses, contingent liabilities, impairment of long-lived assets, revenue recognition, the valuation of equity-based compensation, common stock, restricted common stock, and income taxes. The Company bases its estimates on various assumptions that the Company believes to be reasonable under the circumstances. Actual results could differ from those estimates.
Restricted Cash and Investments	Restricted Cash and Investments Restricted cash consists of certificate of deposit accounts that are pledged as collateral for the Company’s San Diego facility lease. Restricted cash was approximately $0.1 million as of September 30, 2024 and December 31, 2023, respectively. The Company invests its excess cash in investment grade, short-term, fixed income securities and recognizes purchased securities on the settlement date. All investments have been classified as “available-for-sale” in the unaudited condensed consolidated balance sheets and are carried at estimated fair value based upon quoted market prices or pricing models for similar securities. Management determines the appropriate classification of its investments at the time of purchase and re-evaluates such designation as of each balance sheet date. The Company assesses its available-for-sale securities under the available-for-sale security impairment model in ASC Topic 326, Financial Instruments - Credit Losses ("ASC 326") as of each reporting date in order to determine if a portion of any decline in fair value below carrying value is the result of a credit loss. The Company records credit losses in the unaudited condensed consolidated statements of operations and comprehensive loss as credit loss expense, which is limited to the difference between the fair value and the amortized cost of the security. To date, the Company has not recorded any credit losses on its available-for-sale securities. Declines in fair value below carrying value attributable to non-credit related factors are recorded as accumulated other comprehensive loss, which is a separate component of stockholders’ equity. Realized gains and losses are reported in other income (expense), net. Interest on short-term investments is included in other income (expense), net. The Company’s investments are classified as current assets which reflects management’s intention to use the proceeds from sales of these securities to fund its operations, as necessary.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash and cash equivalents, investments and restricted cash. The Company’s investment policy restricts cash investments to high credit quality, investment grade investments. The Company’s investment policy provides guidelines and limits regarding investment type, concentration, credit quality, and maturity aimed at maintaining sufficient liquidity to satisfy operating and working capital requirements along with strategic initiatives, preserving capital, and minimizing risk of capital loss while generating returns on its investments. The Company is exposed to credit risk in the event of default by the issuer or the institutions holding the cash and cash equivalents to the extent of the amounts recorded on the balance sheets. The Company has no off-balance sheet risk, such as foreign exchange contracts, option contracts or other foreign-hedging arrangements.
Fair Value Measurements	Fair Value Measurements The Company applies fair value accounting for all financial assets and liabilities and non-financial assets and liabilities that are recognized or disclosed at fair value in the unaudited condensed consolidated financial statements on a recurring basis. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The fair value hierarchy requires that an entity maximize the use of observable inputs when estimating fair value. The fair value hierarchy includes the following three-level classification which is based on the market observability of the inputs used for estimating the fair value of the assets or liabilities being measured: Level 1 – Quoted market prices in active markets for identical assets or liabilities. Level 2 – Observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 – Inputs that are generally unobservable and typically reflect management’s estimate of assumptions that a market participant would use in pricing the asset or liability. Fair value accounting is applied for all financial assets and liabilities and non-financial assets and liabilities that are recognized at fair value in the unaudited condensed consolidated financial statements on a recurring basis (at least annually). To the extent the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair values requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized as Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement.
Stock-Based Compensation	Stock-Based Compensation The Company accounts for stock-based compensation expense related to stock options and restricted stock units, ("RSUs"), by estimating the fair value on the date of grant. The fair value of RSUs granted to employees is the closing price of the Company’s common stock on the date of grant. The Company estimates the fair value of stock options granted to employees and non-employees using the Black-Scholes option pricing model. The Company recognizes stock-based compensation expense, over the requisite service period, based on the vesting provisions of the individual grants. Generally, the Company issues stock-based awards with only service-based vesting conditions and records the expense for these awards using the straight-line method. The Company accounts for forfeitures when they occur. The Black-Scholes option pricing model requires inputs based on certain subjective assumptions, including (a) the expected stock price volatility, (b) the expected term of the award, (c) the risk-free interest rate and (d) expected dividend yields. Due to the lack of a public market for the Company’s common stock until July 21, 2023, and lack of company- specific historical and implied volatility data, the Company has based its computation of expected volatility on the average historical volatility of a representative group of public companies with similar characteristics to the Company, including stage of product development and life science industry focus. The historical volatility is calculated based on a period of time commensurate with the expected term. The Company uses the simplified method as prescribed by the U.S. Securities and Exchange Commission Staff Accounting Bulletin No. 107, Share-Based Payment, to calculate the expected term for options granted to employees as it does not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term. The expected term is applied to the stock option grant group as a whole, as the Company does not expect substantially different exercise or post-vesting termination behavior among its employee population. The risk-free interest rate is based on a treasury instrument whose term is consistent with the expected term of the stock options. The expected dividend yield is assumed to be zero as the Company has never paid dividends and has no current plans to pay any dividends on its common stock.
Determination of Fair Value of Common Stock	Determination of Fair Value of Common Stock After the Company's IPO in July 2023, the fair value of common stock is determined using the closing price of the Company's common stock on the Nasdaq Global Market. Prior to the IPO, there were significant judgments and estimates inherent in the determination of the fair value of the Company’s common stock. These estimates and assumptions include a number of objective and subjective factors, including, among other things, external market conditions, the prices at which the Company sold shares of its convertible preferred stock, the superior rights and preferences of securities senior to its common stock at the time of, and the likelihood of, achieving a liquidity event, such as an initial public offering or sale of the Company. The approach to estimating the fair market value of common stock is consistent with the methods outlined in the American Institute of Certified Public Accountants’ Accounting and Valuation Guide, Valuation of Privately-Held Company Equity Securities Issued as Compensation (the “Practice Aid”). In valuing the Company’s common stock prior to the IPO, the equity value of the business was determined using the backsolve method, a form of the subject company transaction method, wherein the equity value for a privately held company is derived from a recent transaction in the company’s own securities. The value is then allocated using the hybrid method allocation methodology. For grants made subsequent to September 30, 2018 but prior to the IPO, the Company used a hybrid method, which is a hybrid between the OPM and the probability-weighted expected return method (“PWERM”). The hybrid method is a combination of the PWERM and OPM. The OPM allocates the overall Company value to the various share classes based on differences in liquidation preferences, participation rights, dividend policy and conversion rights, using a series of call options. The call right is valued using a Black-Scholes option pricing model. The PWERM employs additional information not used in the OPM, including various market approach calculations depending upon the likelihood of various discrete future liquidity scenarios, such as an initial public offering or sale of the Company, as well as the probability of remaining a private company. In a hybrid method, various exit scenarios are analyzed. A discount for lack of marketability of the Company’s common stock was then applied to arrive at an indication of value for the common stock.
Contingent Consideration	Contingent Consideration Consideration paid related to the Myst Merger Agreement (see Note 7 - Asset Acquisition for additional information) may include potential future payments that are contingent upon the Company achieving certain milestones in the future. Contingent consideration liabilities are measured at their estimated fair value as of the date of the unaudited condensed consolidated balance sheets using a probability-based income approach based on the monetary value of the milestone payment discounted for the likelihood of achieving the milestone and a present value factor based on the timing of when the milestone is expected to be achieved. Contingent consideration liabilities expected to be settled within 12 months after the balance sheet date are presented in current liabilities, with the non-current portion recorded under other liabilities, non-current in the unaudited condensed consolidated balance sheets. Changes in the fair value of the contingent consideration are recorded as research and development expenses in the unaudited condensed consolidated statement of operations and comprehensive loss.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging Contracts in Entity’s Own Equity (Subtopic 815-40) (“ASU 2020-06”), which reduces the number of accounting models for convertible debt instruments and convertible preferred stock as well as amends the derivatives scope exception for contracts in an entity’s own equity. ASU 2020-06 is effective for the Company on January 1, 2024. The adoption did not have a material impact on the unaudited condensed consolidated financial statements.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280)—Improvements to Reportable Segment Disclosures (“ASU 2023-07”). ASU 2023-07 requires that an entity disclose significant segment expenses impacting profit and loss that are regularly provided to the chief operating decision maker. The update is required to be applied retrospectively to prior periods presented, based on the significant segment expense categories identified and disclosed in the period of adoption. The amendments in ASU 2023-07 are required to be adopted for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. The Company is currently evaluating the potential impact that this standard may have on its unaudited condensed consolidated financial statements and related disclosures. In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740)—Improvements to Income Tax Disclosures (“ASU 2023-09”). ASU 2023-09 requires that an entity disclose specific categories in the effective tax rate reconciliation as well as provide additional information for reconciling items that meet a quantitative threshold. Further, ASU 2023-09 requires certain disclosures of state versus federal income tax expense and taxes paid. The amendments in ASU 2023-09 are required to be adopted for fiscal years beginning after December 15, 2024. Early adoption is permitted for annual financial statements that have not yet been issued. The amendments should be applied on a prospective basis although retrospective application is permitted. The Company is currently evaluating the potential impact that this standard may have on its unaudited condensed consolidated financial statements and related disclosures.

Income Taxes - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Federal income tax expense	$ 0	$ 0
Benefit (provision) for income taxes	$ 0	$ (100,000)

Legal Proceedings - Additional Information (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Loss contingency reserve for litigation liabilities	$ 0	$ 0

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Operating Activities
Net loss	$ (57,965)	$ (38,750)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	2,972	3,130
Loss on disposal of property and equipment		324
Depreciation and amortization	1,498	2,139
Accretion of premium on short term investments	(1,758)	(1,108)
Change in fair value of contingent consideration liability	(49)	1,750
Changes in operating assets and liabilities:
Accounts receivable - collaboration agreement	194	8,511
Prepaid expenses	976	(2,295)
Other current assets	781
Operating lease liabilities	(140)	(72)
Accounts payable	524	(1,052)
Change in contingent consideration liability		(1,477)
Accrued compensation and other accrued liabilities	1,735	(1,945)
Other non-current assets	270	(497)
Deferred revenue		(19,306)
Net cash flows used in operating activities	(50,962)	(50,648)
Investing Activities
Proceeds from maturities of short-term investments	64,250	55,750
Purchase of short-term investments	(6,741)	(77,469)
Proceeds from sale of property and equipment	25	180
Purchases of property and equipment	(248)	(1,249)
Net cash flows provided by (used in) investing activities	57,286	(22,788)
Financing Activities
Proceeds from issuance of common stock, net of issuance costs		78,018
Payment of contingent consideration related to Myst milestone		(898)
Payments of financing costs	(33)
Proceeds from exercise of stock options	44	95
Net cash flows provided by financing activities	11	77,215
Net increase in cash, cash equivalents and restricted cash	6,335	3,779
Cash, cash equivalents and restricted cash at beginning of the period	17,914	35,113
Cash, cash equivalents and restricted cash at end of the period	24,249	38,892
Supplemental Disclosure of Cash Flow Information:
Cash paid for income taxes	$ 119
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Accretion of redeemable convertible preferred stock		39
Conversion of convertible preferred stock to common stock upon closing of IPO		171,983
Equity issuance costs included in accrued liabilities		179
Issuance of common stock to settle Myst contingent consideration liability		$ 2,812

Net Loss per Share

9 Months Ended

Sep. 30, 2024

Earnings Per Share [Abstract]

Net Loss per Share

13. Net Loss per Share

Basic and diluted net loss per share attributed to common stockholders is calculated by dividing net loss attributed to common stockholders by the weighted average number of common shares outstanding during the period, without consideration for common stock equivalents. The Company’s potentially dilutive shares, which include preferred stock, restricted stock, unvested RSUs and options to purchase common stock, are considered to be common stock equivalents and are only included in the calculation of diluted net loss per share when their effect is dilutive. Potentially dilutive common shares have been excluded from the diluted net loss per common share computations in all periods presented because such securities have an anti-dilutive effect on net loss per common share due to the Company’s net loss. There are no reconciling items used to calculate the weighted-average number of total common shares outstanding for basic and diluted net loss per common share.

The following outstanding potentially dilutive shares were excluded from the computation of diluted net loss per share attributable to common stockholders:


	Nine Months Ended September 30,
	2024		2023
Restricted stock		90,740		181,480
Unvested RSUs		104,093		—
Options to purchase common stock		3,137,504		2,587,798
Total		3,332,337		2,769,278

Leases - Additional Information (Detail) $ in Thousands		1 Months Ended							9 Months Ended
Leases - Additional Information (Detail) $ in Thousands	Dec. 01, 2019	Nov. 30, 2022	Sep. 30, 2022 USD ($)	Mar. 31, 2022	Jun. 30, 2021 SquareFeet	May 31, 2019 SquareFeet	Jan. 31, 2019 SquareFeet	Jul. 31, 2018 SquareFeet	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Nov. 30, 2019 USD ($)	Nov. 01, 2018
Lessee, Lease, Description [Line Items]
Operating lease, impairment loss \| $			$ 500
Lessee, operating lease, liability, to be paid \| $									$ 1,742
Payments for rent \| $									$ 800	$ 1,200
Operating lease agreement [Member]
Lessee, Lease, Description [Line Items]
Number of square feet for lease \| SquareFeet						9,423
Lessee, operating lease, term of contract	5 years
Lessee, operating lease, option to extend	one renewal option for a period of five years
Lessee, operating lease, renewal term	5 years
Office space [Member] \| Operating lease agreement [Member]
Lessee, Lease, Description [Line Items]
Number of square feet for lease \| SquareFeet								6,500
Lessee, operating lease, term of contract												7 years 3 months
Laboratory space [Member] \| Operating lease agreement [Member]
Lessee, Lease, Description [Line Items]
Number of square feet for lease \| SquareFeet							6,000
Lessee, operating lease, term of contract											3 years
Lessee, operating lease, liability, to be paid \| $											$ 100
Lessee, operating lease, option to extend		the lease was extended for a one year period.
Lessee, operating lease, renewal term		1 year
Office and laboratory space [Member] \| Operating lease agreement [Member]
Lessee, Lease, Description [Line Items]
Number of square feet for lease \| SquareFeet					19,474
Lessee, operating lease, term of contract				38 months
Lessee, operating lease, option to extend				one renewal option for a period of three years and commenced in March 2022
Lessee, operating lease, renewal term				3 years

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Millions		9 Months Ended
	Jul. 25, 2023	Sep. 30, 2024	Dec. 31, 2023
Significant Accounting Policies [Line Items]
Restricted cash		$ 0.1	$ 0.1
Description of the reverse stock split arrangement	1-for-7.9872
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]		true
Change in Accounting Principle, Accounting Standards Update, Adoption Date		Jan. 01, 2024
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]		true
Change in Accounting Principle, Accounting Standards Update, Transition Option Elected [Extensible Enumeration]		us-gaap:AccountingStandardsUpdate202006Member

- Definition

Indicates (true false) whether accounting standards update was adopted.

+ References

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- Definition

Date accounting standards update was adopted, in YYYY-MM-DD format.

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+ Details

Equity Based Compensation

9 Months Ended

Sep. 30, 2024

Share-Based Payment Arrangement [Abstract]

Equity Based Compensation

10. Equity Based Compensation

2018 Equity Incentive Plan

In December 2018, the Company adopted the 2018 Equity Incentive Plan (the “2018 Plan”) which provided for the Company to grant incentive stock options or nonqualified stock options for the purchase of common stock, or restricted shares, to employees, members of the board of directors and consultants of the Company. The Company assumed all of the outstanding options under the amended and restated Equity Incentive Plan of Turnstone Biologics Inc. dated October 1, 2016 (the “2016 Plan”) in connection with

the corporate reorganization in December 2018. However, there were no changes to the terms of the options requiring modification accounting.

All options granted under the 2018 Plan have an exercise price, a vesting period determined by the Company’s board of directors and ten-year term as determined and approved by the Company’s board of directors (the board of directors may delegate authority to one of the boards’ committees) at the time of grant. The terms and conditions of the restricted shares are determined by the board of directors at the grant date.

The majority of grants outstanding were approved with a four-year vesting schedule with 25% vesting after one year and the remainder vesting evenly over the remaining 36 months. No further grants will be made under the 2018 Plan. Any outstanding awards granted under these plans will remain subject to the terms of their 2016 and 2018 Plans, respectively, and applicable award agreements.

2023 Equity Incentive Plan

In July 2023, the Company's board of directors and stockholders adopted the 2023 Equity Incentive Plan (the “2023 Plan” and together with the 2018 and 2016 Plans the "Plans") which became effective upon the date of the IPO. Under the 2023 Plan, the Company may grant stock options, stock appreciation rights, restricted stock, RSUs, performance stock awards, performance cash awards and other forms of stock awards to employees, directors and consultants. The maximum term of the stock option grants under the 2023 Plan is ten years and, in general, the awards granted under the 2023 Plan vest over a four-year period from the vesting commencement date. The 2023 Plan does not permit early exercises. The number of shares initially reserved for future issuance under the 2023 Plan was the sum of (1) 1,889,435 new shares, plus (2) 712,503 remaining shares of common stock reserved under the 2018 Plan that became available for issuance upon the effectiveness of the 2023 Plan, and (3) up to 120,949 Returning Shares (as defined in the 2023 Plan), as such shares become available from time to time. The number of shares of common stock reserved for issuance under the 2023 Plan will automatically increase on January 1 of each year, for a period of ten years, from January 1, 2024 continuing through January 1, 2033, by 5% of the total number of shares of common stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares as may be determined by the Company’s board of directors. As of January 1, 2024, an additional 1,154,966 were available for future issuance under the 2023 Plan.

A summary of the stock option activity under the Plans is as follows:


	Number of Shares Underlying Outstanding Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (in thousands)
Outstanding — December 31, 2022		2,529,982		$	8.86		6.8	$	6,912
Options granted		231,662		$	15.12
Options exercised		(23,455	)	$	4.02
Options canceled/forfeited		(150,391	)	$	10.69
Outstanding — September 30, 2023		2,587,798		$	9.35		6.5	$	848
Exercisable — September 30, 2023		1,711,392		$	7.99		5.4	$	848
Vested and expected to vest — September 30, 2023		2,587,798		$	9.35		6.5	$	848


Outstanding — December 31, 2023		3,374,282		$	7.66		7.1	$	352
Options granted		129,165		$	2.73
Options exercised		(29,119	)	$	1.51
Options canceled/forfeited		(336,824	)	$	6.67
Outstanding — September 30, 2024		3,137,504		$	7.62		6.1		—
Exercisable —September 30, 2024
Vested and expected to vest — September 30, 2024		3,137,504		$	7.62		6.1		—

The fair value of each stock option granted to employees and directors was estimated on the date of grant using the Black-Scholes option-pricing model, with the following range of assumptions:


	Nine Months Ended September 30,
	2024	2023
Risk-free interest rate	4.30% - 4.72%	3.89% - 4.59%
Expected term (in years)	5.88 - 6.03	6.07 - 6.20
Dividend yield	0%	0%
Volatility	94.0% - 94.7%	85.8% - 87.3%
Exercise price of stock options granted	$2.68 - $2.88	$9.22 - $16.53

As of December 2023, the Company grants RSUs to employees. The RSU activity is summarized as follows:


	Number of RSUs			Weighted- Average Grant Date Fair Value
Outstanding, non-vested as of December 31, 2023		102,945		$	2.71
Granted		16,384		$	2.75
Cancelled/Forfeited		(15,236	)	$	2.71
Vested/Released		—			—
Outstanding, non-vested as of September 30, 2024		104,093		$	2.72

Stock-based compensation expense for all stock awards, including options, restricted stock and RSUs, included in the Company’s statements of operations is as follows (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Research and development	$	522	$	631	$	1,816	$	1,640
General and administrative	$	385	$	433		1,156		1,490
Total stock-based compensation	$	907	$	1,064	$	2,972	$	3,130

The expense related to awards granted to employees and directors was $3.0 million and $3.1 million for the nine months ended September 30, 2024 and 2023, respectively. The weighted-average grant date Black Scholes fair market value of options granted to employees, directors and consultants during the nine months ended September 30, 2024 and 2023 was $2.14 per share and $11.27 per share, respectively. The aggregate grant date fair value of RSU's granted by the Company during the nine months ended September 30, 2024 was $0.0 million. No RSUs were granted by the Company during the nine months ended September 30, 2023.

As of September 30, 2024, the Company had unrecognized stock-based compensation expense of $5.3 million and $0.2, related to stock options and RSUs, respectively, which is expected to be recognized over a weighted-average period of 2.6 and 3.2 years, respectively.

Restricted Stock

In December 2020, Langer received 725,920 shares as payment related to the Myst Merger Agreement. Of the total issued, the Company restricted 362,960 shares to vest over a four-year period in equal annual installments. As of September 30, 2024, 90,740 shares remain unvested, and the Company had $0.2 million in unrecognized stock-based compensation expense related to unvested restricted stock which is expected to be recognized evenly over 3 months.

2023 Employee Stock Purchase Plan

In July 2023, the Company adopted the Employee Stock Purchase Plan (the “ESPP”), which became effective with the IPO on July 25, 2023. The ESPP was adopted by the Company’s board of directors and stockholders in June 2023. The ESPP initially provides participating employees with the opportunity to purchase up to an aggregate of 222,287 shares of common stock. The number of shares of common stock reserved for issuance will automatically increase on January 1st of each calendar year for a period of up to ten years, commencing on January 1, 2024 and ending on (and including) January 1, 2033, in an amount equal to the lesser of

(i) one percent (1%) of the total number of shares of capital stock outstanding on the last day of the calendar month before the date of the automatic increase, and (ii) 666,680 shares of common stock. Notwithstanding the foregoing, the board may act prior to the first day of any calendar year to provide that there will be no January 1st increase in the share reserve for such calendar year or that the increase in the share reserve for such calendar year will be a lesser number of shares of common stock than would otherwise occur pursuant to the preceding sentence. On January 1, 2024, the shares available for issuance under the ESPP automatically increased by an additional 230,993 shares to 453,280 total shares available to be issued under the ESPP. As of September 30, 2024, there was no enrollment offered to the Company's employees.

Property and Equipment, Net - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Property, Plant and Equipment [Abstract]
Property and equipment depreciation and amortization expense	$ 500	$ 700	$ 1,498	$ 2,139

Agreements

9 Months Ended

Sep. 30, 2024

Agreements [Abstract]

Agreements

6. Agreements

Takeda Pharmaceutical Company Limited

Collaboration Agreement

In November 2019, the Company entered into a discovery, collaboration and license agreement (“Takeda Agreement”) with Millennium Pharmaceuticals, Inc. (also known as Takeda Oncology), a wholly owned subsidiary of Takeda Pharmaceutical Company Limited ("Takeda"). Under the Takeda Agreement, the Company agreed to collaborate with Takeda to co-develop and co-commercialize TBio-6517 (also known as RIVAL-01) (“Development Program”) and to conduct discovery programs to identify additional novel product candidates based on its vaccinia virus platform for independent development (“Discovery Program”).

Under the Takeda Agreement, the Company granted Takeda and its affiliates a worldwide, irrevocable, non-transferable, co-exclusive, sublicensable license under certain of the Company’s know-how and patent rights (“Turnstone Technology”) to make, use, sell, offer for sale, develop, manufacture, and commercialize, or otherwise exploit TBio-6517 (“Licensed Compound”) and products containing TBio-6517 (“Takeda Licensed Products”) in all fields. Takeda granted the Company and the Company’s affiliates an irrevocable, non-transferable, non-exclusive, sublicensable license under certain know-how and patent rights of Takeda (“Takeda Technology”) to make, use, sell, offer for sale, develop, manufacture, and commercialize, or otherwise exploit the Licensed Compound and Takeda Licensed Products in all fields in accordance with joint development, commercialization, and medical affairs plans under the Takeda Agreement. Under the Takeda Agreement, the Company also granted to Takeda and its affiliates a worldwide, non-transferable, non-exclusive, sublicensable license under Turnstone Technology to conduct joint discovery and research activities in all fields in accordance with joint research and discovery plans. Under the Takeda Agreement, Takeda granted the Company a license to Takeda Technology to conduct discovery and research activities in all fields in accordance with joint research and discovery plans. The Company also granted to Takeda and its affiliates an exclusive option to obtain a worldwide, irrevocable, non-transferable, exclusive, sublicensable license under Turnstone Technology to make, use, sell, offer for sale, develop, manufacture, and commercialize, or otherwise exploit (i) selected discovery virus candidates generated and evaluated by the parties under a joint discovery program (“Selected Discovery Candidates”), and (ii) any corresponding licensed products containing a Selected Discovery Candidate (“Licensed Discovery Products”). Takeda may exercise this option with respect to two virus candidates and within a specified option exercise period. The Company granted Takeda and its affiliates a non-exclusive, perpetual, irrevocable, worldwide, sublicensable and fully paid-up license under certain of the Company’s know-how and patents relating to manufacturing improvements developed under the Takeda Agreement solely for use in connection with the manufacture of products that do not comprise or incorporate, and that are not based on, an oncolytic virus. Takeda granted the Company and the Company’s affiliates a non-exclusive, perpetual, irrevocable, worldwide, sublicensable and fully paid-up license under certain of Takeda’s know-how and patents relating to manufacturing improvements developed under the Takeda Agreement solely for use in connection with the manufacture of any and all products. With respect to discovery virus candidates for which Takeda does not exercise its option, Takeda granted the Company a non-exclusive, perpetual, worldwide, sublicensable and royalty-bearing license under certain of its know-how and patents that is necessary or reasonably useful for the exploitation of such declined discovery virus candidates (“Declined Candidate License”).

Responsibilities for the development of Licensed Compounds and Takeda Licensed Products are delineated pursuant to a joint development plan under the terms of the Takeda Agreement. The Company will be responsible for all activities under the joint development plan prior to completion of a Phase 2a clinical trial and Takeda will be responsible for all activities in the joint development plan upon and after completion of the Phase 2a clinical trial. Responsibilities relating to manufacturing, medical affairs, and commercialization of Licensed Compounds and Takeda Licensed Products are delineated pursuant to a manufacturing working plan, joint medical affairs plan and joint commercialization plan, respectively. The Company has the right to reduce or opt-out of its

share of responsibilities for costs and expenses of certain development or commercialization activities for the Takeda Licensed Compounds and Takeda Licensed Products. Responsibilities for the discovery and research of Selected Discovery Candidates are delineated pursuant to joint discovery and research plans under the terms of the Takeda Agreement.

Under the Takeda Agreement, Takeda paid the Company a non-refundable payment of $50.0 million in November 2019 and an additional non-refundable payment of $30.0 million in April, 2020, for the option to license up to two Selected Discovery Candidates, with additional consideration of $15.0 million to be paid by Takeda to the Company for each exercise of such option.

Under the Takeda Agreement, the Company has the right to reduce its share of funding obligations with respect to development activities for the Licensed Compound and Takeda Licensed Products (the “Development Opt-Down Right”), or to opt-out of all further funding obligations with respect to development activities for the Licensed Compound and Takeda Licensed Products (the “Development Opt-Out Right”). Unless and until the Company exercises the Development Opt-Down Right, the parties will share evenly in any operating profits or losses with respect to joint development activities, joint medical affairs activities, and joint commercialization activities. If the Company exercises its Development Opt-Down Right, then starting from the effective date of the exercise of the right, Takeda will bear (and be entitled to) 70% and the Company will bear (and be entitled to) 30% of the operating profits or losses with respect to joint development activities, joint medical affairs activities, and joint commercialization activities. Takeda is obligated to pay the Company (i) up to $200.0 million in aggregate upon achievement of certain clinical and regulatory milestones for the first Takeda Licensed Product to achieve the applicable development milestone event, (ii) up to $150.0 million in aggregate for one-time payments upon achievement of certain sales milestones for each Takeda Licensed Product, (iii) up to $240.0 million in aggregate (if Takeda exercises both options to Selected Discovery Candidates) upon achievement of certain clinical and regulatory milestones for the first Takeda Licensed Discovery Product to achieve applicable development milestone events, and (iv) up to $300.0 million in aggregate (if Takeda exercises both options to Selected Discovery Candidates) for one-time payments upon achievement of certain sales milestones for a Licensed Discovery Product. If the Company exercises its Development Opt-Out Right for the Takeda Licensed Products, then in lieu of the profit and loss share arrangement described above, the Company is entitled to receive tiered low- to high- teen percentage royalties on net sales of all Takeda Licensed Products by the Company or the Company’s sublicensees during the royalty term, which commences on the first commercial sale of a Takeda Licensed Product in a country and ends on the later of the expiration of all licensed patents covering such Licensed Product in such country or ten years after the date of the first commercial sale in such country (“Royalty Term”). For Licensed Discovery Products, the Company is entitled to receive tiered high-single digit to low-teen percentage royalties on net sales of all Licensed Discovery Products by the Company or the Company’s sublicensees during the Royalty Term. Royalty payments are subject to customary reductions.

Takeda has the right to terminate for convenience as follows: (i) prior to the expiration of the option exercise period related to a Discovery Virus Candidate, Takeda may terminate the Takeda Agreement related to such Discovery Virus Candidate and the Discovery Program with 90 days’ notice, (ii) prior to any commercial sale, Takeda may terminate the Takeda Agreement either in its entirety or on a compound-by-compound or region-by-region basis, with six months’ notice and (iii) after a commercial sale, Takeda may terminate the Takeda Agreement either in its entirety or on a compound-by-compound or region-by-region basis, with 12 months’ notice.

Termination of Development Program

On June 13, 2022, Takeda provided six months’ written notice to terminate the Development Program in accordance with its termination for convenience rights, with such termination being effective as of December 13, 2022. During the six months’ notice period, the Company was obligated to continue providing the necessary Development Program services to wind down the program. Upon the effective termination date of December 13, 2022, Takeda’s co-exclusive license to TBio-6517 terminated and the Company is no longer obligated to pursue development of TBio-6517.

Termination of Discovery Program

On January 6, 2023, Takeda provided six months’ written notice to terminate the remainder of the Takeda Agreement, with such termination being effective as of July 6, 2023 (“Effective Termination Date”). On the Effective Termination Date, all options and licenses granted under the Takeda Agreement terminated (except for the Declined Candidate License) and Takeda granted the Company a non-exclusive license under the patent rights and know-how controlled by Takeda as of the Effective Termination Date necessary for the Company to exploit the Licensed Compound and Takeda Licensed Products in the form existing as of the Effective Termination Date for any use worldwide, subject to a royalty to be agreed upon by Takeda and the Company. As of March 31, 2023,

the Company ceased all work under the Takeda Agreement and there were no remaining estimated services associated with the obligations under the Takeda Agreement as of the effective termination date of July 6, 2023.

Accounting Analysis

The Company assessed the promised goods and services under the Takeda Agreement in accordance with ASC Topic 606, Revenue from Contracts with Customers ("ASC 606"), and determined that, at inception, the Takeda Agreement includes the following performance obligations: (i) research, development and manufacturing services under the Development Program for the completion of clinical trials through Phase 2a for RIVAL-01 and a co-exclusive license to exploit RIVAL-01 (“Development Program Performance Obligation”); and (ii) research and development services under the Discovery Program to identify and optimize four Selected Discovery Candidates for further development (“Discovery Program Performance Obligation”). The individual promises under the Development Program including research, development, manufacturing for clinical trials, and the co-exclusive license to RIVAL-01 are not individually distinct as they represent inputs into a combined output of advancing RIVAL-01 through the Phase 2a clinical trial. Therefore, all promises under the Development Program represent a single performance obligation. Similarly, the research and development services under the Discovery Program represent a single research program aimed at generating four Selected Discovery Candidates and therefore represents a single performance obligation. The Development Program promises are distinct from the promises under the Discovery Program, as the benefits under each program are separately identifiable. Each program has a separate work plan and the promises to be provided under the Development Program do not relate to the promises to be provided under the Discovery Program.

The Company concluded that Takeda’s license options under the Discovery Program do not represent material rights, and therefore are not performance obligations, as the Company is entitled to an additional $15.0 million payment for each license option exercised, which approximates the estimated standalone selling price of the underlying license.

The total transaction price at contract inception is $158.6 million, comprised of the following components:

•

Fixed consideration of $80.0 million including a non-refundable up-front payment of $50.0 million in November 2019 and another non-refundable payment of $30.0 million that was due on April 1, 2020 and received in April 2020.

•

Variable consideration related to the expense sharing under the Development Program. These amounts are determinable based on the Development Program plan and budget, and the Company has a contractual right to the payment of costs incurred under the agreed upon plan. Consistent with the expected value method, the Company estimated that it will receive $58.6 million under the expense sharing through the completion of the Phase IIa clinical trial. The Company has concluded that these amounts do not require a constraint and are included in the transaction price at inception. The Company has evaluated this estimate at each reporting date and updated the estimate based on information available.

•

Variable consideration for the development milestones under the Development Program. The Company uses the most likely amount method to value this variable consideration as there are only two possible outcomes of achieving the individual milestones. Under the Development Program, the first milestone of $20.0 million is due upon acceptance of an Investigational New Drug Application ("IND") by the U.S. Food and Drug Administration ("FDA"). At inception, the Company concluded that achievement of this milestone was highly probable and therefore the $20.0 million was included in the transaction price and was received in March 2020. The second milestone of $15.0 million under the Development Program is due upon the initiation of the first Phase 2 clinical trial for a licensed product. The Company has determined that the most likely amount is $15.0 million, however, the Company will not include this $15.0 million milestone in the transaction price until it becomes probable that a significant reversal of cumulative revenue will not occur.

Additional consideration to be paid to the Company includes development and sales milestones, profit and loss share, royalties and option exercise payments. These additional payments are achievable only after the completion of the Phase 2a clinical trial under the Development Program or exercise of the license options under the Discovery Program and therefore are excluded from the transaction price. Additionally, Takeda’s equity purchase commitments of up to $20.0 million are at fair value and therefore no non-cash consideration has been included as a component of the transaction price.

The Company allocated the transaction price to the separate performance obligations based on their relative standalone selling prices. The Company determined the standalone selling price of the Development Program Performance Obligation based on the costs incurred to develop RIVAL-01 plus the estimated costs to perform the research, development and manufacturing services through the completion of the Phase 2a clinical trial, inclusive of a reasonable profit margin. The Company determined the standalone selling price of the Discovery Program Performance Obligation based on the estimated costs to discover and research four Selected Discovery Candidates, inclusive of a reasonable profit margin. Significant inputs used to determine the standalone selling prices of the

performance obligations include the length of time required, the internal hours expected to be incurred on the services, and the amount of third-party expenses that will be incurred to complete the performance obligations.

The Company recognizes the amounts associated with these performance obligations on a proportional performance basis over the contract term using input-based measurements of total cost of research and development incurred to estimate the proportion performed as compared to the estimated total cost and remeasures its progress towards completion at the end of each reporting period.

As of December 31, 2021, the transaction price was updated to $192.6 million to reflect an increase in the variable consideration related to the expense sharing under the Development Program from $58.6 million at inception to $92.6 million.

The Company determined that the notice of termination on June 13, 2022, represented a modification of the arrangement under ASC 606 and that the transaction price should be updated and re-allocated to the Development Program Performance Obligation and the Discovery Program Performance Obligation based on their standalone selling prices, as follows:


Performance Obligations	Price Pre- Modification	Price at Modification
Development Program	$166.3 million	$134.3 million
Discovery Program	$26.3 million	$21.2 million
Total	$192.6 million	$155.5 million

Additionally, the Company updated its measure of progress for each performance obligation as of the modification date and recorded a cumulative adjustment that increased collaboration revenue by $31.6 million on the partially satisfied remaining performance obligations, as the remaining services to be performed under each of the performance obligations are not distinct from the services prior to the modification.

Costs incurred relating to the Takeda Agreement consist of internal and external research and development costs, which primarily include salaries and benefits, lab supplies, and preclinical research studies. All of these costs have been included in research and development expenses in the Company’s unaudited condensed consolidated statements of operations and comprehensive loss during the three months ended March 31, 2023 and in prior years.

The Company recognized the remaining deferred revenue balance during the three months ended March 31, 2023 as the Company concluded that there were no remaining estimated services to be performed associated with the obligations under the Takeda Agreement. The Company recognized collaboration revenue related to the Takeda Agreement for the nine months ended September 30, 2024 and 2023 of $0.0 million and $19.3 million, respectively. Receivables related to reimbursable costs expected to be received from Takeda for research and development services performed under the Development Program at September 30, 2024 and December 31, 2023 were $0.0 million and $0.2 million, respectively.

H. Lee Moffitt Cancer Center

Master Collaboration Agreement

In January 2021, the Company entered into an amended and restated master collaboration agreement (the “Moffitt Agreement”), with Moffitt, to amend a then-existing master collaboration agreement from November 2019, as amended March 2020, between Moffitt and the Company’s now wholly-owned subsidiary, Myst, with the intent to continue to work collaboratively in the research of cancer immunotherapies.

Each party granted the other party a right to use its research materials for performance of the research plans agreed to by the parties (the “Research Plans”). Each party granted the other party a non-exclusive, worldwide, sublicensable, perpetual, irrevocable, royalty-free license under all inventions invented in performance of a Research Plan and invented jointly by the Company and Moffitt (the “Joint Inventions”) (with certain exclusions) to make, use, sell, offer for sale, import products and services and/or otherwise practice such inventions.

The Company granted Moffitt a royalty free, non-sublicensable, non-transferable, perpetual, non-exclusive license to use and practice certain inventions invented solely by the Company in the performance of a Research Plan for its internal non-commercial research purposes.

Moffitt granted the Company (i) a royalty-free, sublicensable, non-transferable, perpetual, non-exclusive license to use and practice certain inventions invented solely by Moffitt in the performance of a Research Plan (“Moffitt Inventions”), (a) for internal, non-commercial research purposes outside the field of ACT and/or (b) to research, develop, make, use, sell, offer to sell, or import

products and/or services in the field of ACT and (ii) a royalty free, sublicensable, non-transferable, perpetual, non-exclusive license to use and practice certain inventions invented in performance of a Research Plan or through the use of specified Moffitt research materials.

Moffitt granted the Company an option to obtain, with terms to be negotiated in good faith under commercially reasonable terms, a royalty-bearing, sublicensable exclusive license in the Moffitt Inventions, the TCR Inventions, and/or Moffitt’s interest in Joint Inventions. The Company can exercise this option at any time within six months after Moffitt informs the Company of any new invention, and upon the Company’s exercise, the parties will have a period of six months to negotiate the terms of such exclusive license.

The Moffitt Agreement will expire upon the later of (i) four years from the effective date of the Moffitt Agreement or (ii) the termination or expiration of all Research Plans in effect under the Moffitt Agreement, unless extended upon mutual written agreement of the parties. Either party may terminate the Moffitt Agreement for cause upon any uncured breach by the other party or upon the insolvency of the other party.

Moffitt Alliance Agreement

In June 2022, the Company entered into a life science alliance agreement with Moffitt (the “Alliance Agreement”), in order to further expand the Company’s relationship and support the Company’s existing agreements with Moffitt (the “Underlying Agreements”). Pursuant to the Alliance Agreement, the Company will have priority access to Moffitt’s scientific research, manufacturing, and clinical capabilities for the development of novel TIL therapies, including expedited clinical trial activation, enhanced patient screening and data sharing, access to Moffitt’s cellular therapies research and development infrastructure, expanded molecular data sets and biospecimens for research, and allocated cGMP manufacturing capacity for the Company’s product candidates.

Under the Alliance Agreement, the Company is obligated to use commercially reasonable efforts to further develop TIL Products, to manufacture TIL Products, to obtain regulatory approval for at least one TIL Product in the United States and to commercialize TIL Products in all countries in which regulatory approval for a TIL Product has been obtained. For purposes of the Alliance Agreement, TIL Product means any pharmaceutical, biopharmaceutical, or biotechnology TIL product that has been developed by us or Moffitt and is advanced into clinical development under an IND sponsored by Moffitt.

Pursuant to the Alliance Agreement, the Company agreed to pay to Moffitt a total amount of at least $17.5 million (the “Alliance Funding Amount”), for research, development and manufacturing related services that will be paid equally over five years on June 1st of each year starting on June 1, 2023. The Alliance Funding Amount was calculated annually at the conclusion of each payment period, and, to the extent the Company’s annual aggregate payments to Moffitt of $3.5 million exceeded the applicable annual installment amount, the Company would receive a reduction in the amount due for future installment payments based on a predetermined formula agreed to by the parties. To the extent the aggregate annual payments were less than $3.5 million, the Company would prepay the remaining amount due. On June 28, 2024, the Alliance Agreement was amended to remove the true up of the applicable annual installment amount of $3.5 million. The Alliance Funding Amount remains $17.5 million over the five year term.

In connection with the execution of the Alliance Agreement, the Company issued Moffitt 91,721 shares of its common stock. As partial consideration under the Alliance Agreement, the Company also agreed to issue Moffitt an additional 366,884 shares of its common stock in the aggregate upon the satisfaction of certain clinical and regulatory milestones with respect to TIL Products. The issuances of common stock are treated as performance-based stock awards. On February 27, 2023, 91,721 shares were issued due to the achievement of the milestone related to the start of the Phase 1 trial. In addition, upon achievement of certain thresholds for aggregate net sales of all TIL Products, the Company is required to make tiered sales-based milestones payments to Moffitt of up to an aggregate of $50.0 million. With respect to each of the equity and sales milestones described above, TIL Products include any pharmaceutical, biopharmaceutical or biotechnology TIL Product that is developed by the Company or Moffitt and is advanced into clinical development under an IND sponsored by Moffitt.

Unless earlier terminated, the Alliance Agreement will remain in effect for a term of five years and may be extended for additional periods upon the mutual written consent of both parties. Either party may terminate the Alliance Agreement in the event of (i) the other party’s material breach of the Alliance Agreement that remains uncured after ninety days of receiving written notice of such breach (or in the case of breach of payment obligations, within ten days), (ii) the other party’s insolvency and (iii) a pandemic event resulting in government lockdowns or orders that legally compel such party to cease operations or that result in material disruptions in the available workforce and prevents such party from performing its contractual obligations for a period of more than six months. At any time after June 1, 2025, either party may terminate the Alliance Agreement without cause upon sixty days prior

written notice to the other party (a “Termination for Convenience”). Upon a Termination for Convenience, the terminating party shall pay to the other party a termination fee in an amount equal to a low double digit percentage of the then remaining Alliance Funding Amount. Termination or expiry of one or more Underlying Agreements does not affect the term of the Alliance Agreement, which will continue to apply to the remaining ongoing Underlying Agreements.

Equity Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended		3 Months Ended		9 Months Ended
	Jan. 01, 2024	Jul. 31, 2023	Dec. 31, 2020	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share based compensation expense				$ 907	$ 1,064	$ 2,972	$ 3,130
Share-based compensation arrangement by share-based payment award, options, grants in period, weighted average grant date fair value						$ 2.14	$ 11.27
Common Stock, Capital Shares Reserved for Future Issuance				6,806,785		6,806,785		5,454,918
RSUs [Member]
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Aggregate grant date fair value of RSUs granted						$ 0
Number of RSUs granted						16,384	0
Share-based payment arrangement, non-vested award, cost not yet recognized, period for recognition						3 years 2 months 12 days
Share-based compensation arrangement by share-based payment award, equity instruments other than options, nonvested, number				104,093		104,093		102,945
Share-based payment arrangement, nonvested award, cost not yet recognized				$ 200		$ 200
Stock option [Member]
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based payment arrangement, non-vested award, cost not yet recognized, period for recognition						2 years 7 months 6 days
Share-based payment arrangement, nonvested award, cost not yet recognized				$ 5,300		$ 5,300
Myst Merger Agreement [Member] \| Restricted Stock [Member]
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Award requisite service period			4 years
Share-based payment arrangement, non-vested award, cost not yet recognized, period for recognition						3 months
Share-based compensation arrangement by share-based payment award, equity instruments other than options, nonvested, number				90,740		90,740
Share-based payment arrangement, non-vested award, excluding option, cost not yet recognized, amount				$ 200		$ 200
Myst Merger Agreement [Member] \| Timothy Langer [Member]
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Business acquisition, equity interest issued or issuable, number of shares			725,920
Myst Merger Agreement [Member] \| Timothy Langer [Member] \| Restricted Stock [Member]
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Business acquisition, equity interest issued or issuable, number of shares			362,960
2018 Plan [Member]
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Award requisite service period						10 years
Award vesting period						4 years
Share-based compensation arrangement by share-based payment award, award vesting rights, percentage						25.00%
2023 Plan [Member]
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Award vesting period						4 years
Maximum term of options issued under equity incentive plan						10 years
Common stock, capital shares reserved for future issuance increase decrease period		10 years
Share-based compensation arrangement by share-based payment award, percentage of outstanding stock maximum		5.00%
2023 Plan [Member] \| New Shares Under 2023 [Member]
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares available for grant	1,154,966	1,889,435
2023 Plan [Member] \| Remaining Shares From 2018 Plan [Member]
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares available for grant		712,503
2023 Plan [Member] \| Returning Shares [Member]
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares available for grant		120,949
Employee Stock Purchase Plan [Member]
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Number of shares authorized for issuance under share-based payment arrangement	453,280	222,287
Shares available for issuance automatically increased by additional shares	230,993
Common Stock, Capital Shares Reserved for Future Issuance		666,680
Common stock, capital shares reserved for future issuance increase decrease period		10 years
Share-based compensation arrangement by share-based payment award, percentage of outstanding stock maximum		1.00%

Equity Based Compensation (Tables)

9 Months Ended

Sep. 30, 2024

Share-Based Payment Arrangement [Abstract]

Schedule of stock option plan activity

A summary of the stock option activity under the Plans is as follows:


	Number of Shares Underlying Outstanding Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (in thousands)
Outstanding — December 31, 2022		2,529,982		$	8.86		6.8	$	6,912
Options granted		231,662		$	15.12
Options exercised		(23,455	)	$	4.02
Options canceled/forfeited		(150,391	)	$	10.69
Outstanding — September 30, 2023		2,587,798		$	9.35		6.5	$	848
Exercisable — September 30, 2023		1,711,392		$	7.99		5.4	$	848
Vested and expected to vest — September 30, 2023		2,587,798		$	9.35		6.5	$	848


Outstanding — December 31, 2023		3,374,282		$	7.66		7.1	$	352
Options granted		129,165		$	2.73
Options exercised		(29,119	)	$	1.51
Options canceled/forfeited		(336,824	)	$	6.67
Outstanding — September 30, 2024		3,137,504		$	7.62		6.1		—
Exercisable —September 30, 2024
Vested and expected to vest — September 30, 2024		3,137,504		$	7.62		6.1		—

Schedule of fair value assumption of stock option activity

The fair value of each stock option granted to employees and directors was estimated on the date of grant using the Black-Scholes option-pricing model, with the following range of assumptions:


	Nine Months Ended September 30,
	2024	2023
Risk-free interest rate	4.30% - 4.72%	3.89% - 4.59%
Expected term (in years)	5.88 - 6.03	6.07 - 6.20
Dividend yield	0%	0%
Volatility	94.0% - 94.7%	85.8% - 87.3%
Exercise price of stock options granted	$2.68 - $2.88	$9.22 - $16.53

Summary of RSU activity

As of December 2023, the Company grants RSUs to employees. The RSU activity is summarized as follows:


	Number of RSUs			Weighted- Average Grant Date Fair Value
Outstanding, non-vested as of December 31, 2023		102,945		$	2.71
Granted		16,384		$	2.75
Cancelled/Forfeited		(15,236	)	$	2.71
Vested/Released		—			—
Outstanding, non-vested as of September 30, 2024		104,093		$	2.72

Schedule of stock based compensation for stock awards

Stock-based compensation expense for all stock awards, including options, restricted stock and RSUs, included in the Company’s statements of operations is as follows (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Research and development	$	522	$	631	$	1,816	$	1,640
General and administrative	$	385	$	433		1,156		1,490
Total stock-based compensation	$	907	$	1,064	$	2,972	$	3,130

Accrued Expenses and Other Current Liabilities (Tables)

9 Months Ended

Sep. 30, 2024

Accrued Liabilities and Other Liabilities [Abstract]

Schedule of Accrued Liabilities and Other Current Liabilities

Accrued expenses and other current liabilities consist of the following (in thousands):


	September 30,		December 31,
	2024		2023
Research and development expense	$	8,044	$	5,675
Professional and consulting expense		760		641
Compensation		2,840		3,593
Total accrued expenses and other current liabilities	$	11,644	$	9,909

Nature of the Business and Basis of Presentation

9 Months Ended

Sep. 30, 2024

Business Description And Basis Of Presentation [Abstract]

Nature of the Business and Basis of Presentation

1. Nature of the Business and Basis of Presentation

Organization

Turnstone Biologics Corp. (the “Company” or “Turnstone”) is a clinical stage biotechnology company focused on developing new medicines to treat and cure patients with solid tumors. Turnstone is pioneering a differentiated approach to tumor infiltrating lymphocytes (“TILs”), a clinically validated technology for treating solid tumors. The Company is developing next generation TIL therapies by selecting the most potent and tumor reactive T cells (“Selected TILs”). The Company has three ongoing Phase 1 clinical trials for TIDAL-01, including a multi-site trial for the treatment of colorectal cancer, head and neck cancer, and uveal melanoma, and two investigator sponsored trials with H. Lee Moffitt Cancer Center and Research Institute, Inc., ("Moffitt"), across colorectal cancer, head and neck cancer, and uveal melanoma. The Company’s headquarters are located in San Diego, California.

Reverse Stock Split

On July 14, 2023, the Company effected a 1-for-7.9872 reverse stock split (“Reverse Split”) of its issued and outstanding shares of common stock and redeemable convertible preferred stock. All share and per share amounts included in the accompanying unaudited condensed consolidated financial statements and related notes have been retroactively adjusted, where applicable, to reflect the Reverse Split, including reclassifying an amount equal to the reduction in par value of common stock to additional paid-in capital. Shares of common stock, underlying outstanding stock options, and restricted stock were proportionately reduced and the respective exercise prices, if applicable, were proportionately increased in accordance with the terms of the appropriate securities agreements. Stockholders entitled to fractional shares as a result of the Reverse Split received a cash payment in lieu of receiving fractional shares.

Initial Public Offering

On July 25, 2023, the Company completed its initial public offering ("IPO") pursuant to which it issued and sold an aggregate of 6,666,667 shares of common stock at a price to the public of $12.00 per share. Aggregate net proceeds to the Company were $68.7 million after deducting underwriting discounts and commissions of $5.6 million and other offering expenses of $5.7 million. On August 15, 2023, the underwriters exercised their option to purchase an additional 651,608 shares of common stock at $12.00 per share. Aggregate net proceeds to the Company were $7.3 million after deducting underwriting discounts and commissions of $0.5 million. Upon the closing of the IPO, all outstanding shares of redeemable convertible preferred stock automatically converted into shares of common stock. Subsequent to the closing of the IPO, there were no shares of redeemable convertible preferred stock outstanding.

In connection with the closing of the IPO, the Company filed its Amended and Restated Certificate of Incorporation which provides that the authorized capital stock of the Company is 500,000,000 shares consisting of 490,000,000 shares of common stock and 10,000,000 shares of undesignated preferred stock, both with a par value of $0.001 per share.

Nasdaq Deficiency Notice

On September 27, 2024, the Company received a deficiency notice (the “Notice”) from the Listing Qualifications Staff of The Nasdaq Stock Market LLC (“Nasdaq”) notifying the Company that, for the last 30 consecutive business days, the bid price of the Company’s common stock had closed below $1.00 per share, the minimum closing bid price required by the continued listing requirements of Nasdaq Listing Rule 5450(a)(1). The Notice has no immediate effect on the listing of the Company’s common stock on Nasdaq.

Liquidity and Capital Resources

Going Concern

The accompanying consolidated financial statements have been prepared assuming the Company will continue as a going concern, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business, and do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or amounts and classification of liabilities that may result from the outcome of this uncertainty. Management is required to perform a two-step analysis over the Company’s ability to continue as a going concern. Management must first evaluate whether there are conditions and events that raise substantial doubt about the Company’s ability to continue as a going concern (Step 1). If management concludes that substantial doubt is raised, management is also required to consider whether its plans alleviate that doubt (Step 2).

However, the Company incurred a net loss and negative cash flows from operations during the nine months ended September 30, 2024 and management’s cash flow forecasts indicate that based on the Company’s expected future operating losses and negative cash flows, there is substantial doubt about the Company’s ability to continue as a going concern for 12 months after the date the unaudited consolidated financial statements are filed with the SEC.

The Company’s ability to continue as a going concern is dependent upon its ability to raise additional funding. Management intends to raise additional capital through equity offerings, debt financings or other capital sources, including potential collaborations, licenses and other similar arrangements. However, the Company may not be able to secure additional financing in a timely manner or on favorable terms, if at all. Furthermore, if the Company issues equity securities to raise additional funds, its existing stockholders may experience dilution, and the new equity securities may have rights, preferences and privileges senior to those of the Company’s existing stockholders. If the Company raises additional funds through collaboration, licensing or other similar arrangements, it may be necessary to relinquish valuable rights to its current and potential future product candidates and programs on terms that are not favorable to the Company. As a result of adverse macroeconomic and geopolitical developments, recent and potential future bank failures, actual or anticipated changes in interest rates, economic inflation and the responses by central banking authorities to control such inflation, the global credit and financial markets have experienced volatility and disruptions, including diminished liquidity and credit availability, declines in consumer confidence, declines in economic growth, increases in unemployment rates and uncertainty about economic stability. If the equity and credit markets deteriorate in the future, it may make any additional debt or equity financing more difficult, more costly, and more dilutive. If the Company is unable to raise capital when needed or on attractive terms, it would be forced to delay, reduce or eliminate its research and development programs or other operations. Even if the Company raises additional capital, it may be insufficient to continue its development as currently planned, which could have a material adverse effect on the Company’s business, operating results and financial condition, and the Company’s ability to achieve its intended business objectives. If any of these events occur, the Company’s ability to achieve the development and commercialization goals would be adversely affected.

Sources of Liquidity

Since its inception, the Company has devoted substantially all of its efforts and financial resources to organizing and staffing the Company, business planning, raising capital, discovering product candidates and securing related intellectual property rights, and conducting research and development activities for its Selected TIL programs and product candidates. The Company does not have any products approved for sale, has not generated any revenue from product sales and has incurred overall net losses since commencement of the Company’s operations, including a net loss of $58.0 million and $38.8 million for the nine months ended September 30, 2024 and 2023, respectively. The Company has financed its operations through the issuance and sale of shares of the Company’s redeemable convertible preferred stock, from collaboration revenue received pursuant to certain collaboration agreements, and most recently, with proceeds from the IPO completed on July 25, 2023 and the exercise of the underwriters option to purchase additional shares on August 15, 2023. As of September 30, 2024, the Company had an accumulated deficit of $234.7 million. The Company expects to continue to generate significant operating losses for the foreseeable future.

On April 26, 2024 (the “Loan Closing Date”), the Company entered into a Loan and Security Agreement ("LSA") with Banc of California ("BOC") for a revolving credit facility in an aggregate principal amount of up to $20 million with annual interest at the greater of the Prime Rate (as defined in the LSA) or 4.25%. This LSA includes a covenant requiring the Company to (i) receive positive interim Phase 1 data for TIDAL-01 (as determined by the Company’s board of directors), which was achieved in August 2024 and (ii) receive at least $40.0 million in new funding from the sale of equity, partnerships, and/or business development payments, in each case, by March 31, 2025. If the Company fails to comply with any of the foregoing covenants, the Lender may terminate the commitments to make further loans and declare all of the obligations of the Company under the LSA to be immediately due and payable. As of September 30, 2024, no amounts have been drawn under the LSA (see Note 8 - Term Loan for additional information).

The Company intends to fund future operations and future capital funding needs through equity and/or debt financings, as well as possible asset sales, licensing transactions, and collaborations or strategic partnerships with other companies. The sale of equity or convertible debt could result in additional dilution to stockholders. The incurrence of indebtedness would result in debt service obligations and could result in operating and financial covenants that would restrict the Company’s operations. The Company can provide no assurance that sufficient financing will be available on acceptable terms, if at all. If the Company is not able to secure adequate additional funding it may be forced to make reductions in spending, extend payment terms with suppliers, liquidate assets where possible, and/or suspend or curtail planned programs. Any of these actions could materially harm the Company’s business.

Risks and Uncertainties

The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including, but not limited to, development by competitors of new technological innovations, dependence on key personnel, protection of proprietary technology, compliance with government regulations and the ability to secure additional capital to fund operations. Product candidates currently under development will require significant additional research and development efforts, including

non-clinical and clinical testing and regulatory approval, prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance and reporting capabilities. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales.

Agreements - Additional Information (Detail) - USD ($) $ in Thousands						1 Months Ended		6 Months Ended	9 Months Ended
	Aug. 15, 2023	Feb. 27, 2023	Jun. 01, 2022	Apr. 30, 2020	Nov. 30, 2019	Apr. 30, 2020	Nov. 30, 2019	Jun. 30, 2022	Sep. 30, 2024	Sep. 30, 2023	Jul. 31, 2024	Jun. 28, 2024	Dec. 31, 2023	Dec. 31, 2021
Inflow From Issuance Of Intangible Asset
Additional revenue recognized on change in contract modification										$ 19,306
Number of new stock issued during the period	651,608
Takeda Agreement [Member]
Inflow From Issuance Of Intangible Asset
Percentage of share of operating profit or loss					30.00%
Performance Obligations					$ 158,600		$ 158,600							$ 192,600
Additional revenue recognized on change in contract modification								$ 31,600
Collaborative Arrangement, Revenue Not from Contract with Customer, Statement of Income or Comprehensive Income [Extensible Enumeration]									Additional revenue recognized on change in contract modification
Revenue from collaborative arrangement									$ 0	$ 19,300
Collaborative arrangement additional consideration receivable for license option					15,000		15,000
Revenue, performance obligation fixed aggregate consideration					80,000		80,000
Revenue, performance obligation fixed consideration Non refundable upfront payment received							50,000
Revenue, performance obligation fixed consideration Non refundable payment received						$ 30,000
Estimated compensation earning from project expense sharing					58,600		58,600							$ 92,600
Takeda Agreement [Member] \| Development Program [Member]
Inflow From Issuance Of Intangible Asset
Receivables related to reimbursable costs									0				$ 200
Takeda Agreement [Member] \| Development Program [Member] \| First Milestone Payment [Member]
Inflow From Issuance Of Intangible Asset
Milestone payment receivable					20,000		20,000
Performance Obligations					20,000		20,000
Takeda Agreement [Member] \| Development Program [Member] \| Second Milestone Payment [Member]
Inflow From Issuance Of Intangible Asset
Milestone payment receivable					15,000		15,000
Takeda Agreement [Member] \| Development Program [Member] \| Third Milestone Payment [Member]
Inflow From Issuance Of Intangible Asset
Milestone payment receivable					15,000		15,000
Takeda Agreement [Member] \| Discovery Program [Member]
Inflow From Issuance Of Intangible Asset
Equity purchase commitments by counter party					20,000		20,000
Takeda Pharmaceutical Company Limited [Member] \| Takeda Agreement [Member]
Inflow From Issuance Of Intangible Asset
Inflow From Issuance Of Intangible Asset				$ 30,000	$ 50,000
Percentage of share of operating profit or loss					70.00%
Collaborative arrangement additional consideration receivable				$ 15,000		$ 15,000
Takeda Pharmaceutical Company Limited [Member] \| Takeda Agreement [Member] \| Clinical and Regulatory Milestones On Development Program [Member]
Inflow From Issuance Of Intangible Asset
Milestone payment receivable					$ 200,000		200,000
Takeda Pharmaceutical Company Limited [Member] \| Takeda Agreement [Member] \| Sales Milestones On Development Program [Member]
Inflow From Issuance Of Intangible Asset
Milestone payment receivable					150,000		150,000
Takeda Pharmaceutical Company Limited [Member] \| Takeda Agreement [Member] \| Clinical and Regulatory Milestones on Licensed Discovery Product [Member]
Inflow From Issuance Of Intangible Asset
Milestone payment receivable					240,000		240,000
Takeda Pharmaceutical Company Limited [Member] \| Takeda Agreement [Member] \| Sales Milestones on Licensed Discovery Product [Member]
Inflow From Issuance Of Intangible Asset
Milestone payment receivable					$ 300,000		$ 300,000
H. Lee Moffitt Cancer Center [Member] \| Alliance Agreement [Member]
Inflow From Issuance Of Intangible Asset
Research development and manufacturing services aggregate annual amount			$ 3,500
Collaborative arrangement aggregate consideration payable											$ 17,500
Number of new stock issued during the period		91,721
Collaborative arrangement aggregate consideration remains									$ 17,500
Research development and manufacturing services amended to remove the true up annual installment amount												$ 3,500
H. Lee Moffitt Cancer Center [Member] \| Alliance Agreement [Member] \| Performance Shares [Member]
Inflow From Issuance Of Intangible Asset
Number of new stock issued during the period			91,721
Number of non-vested equity-based payment instruments			366,884
H. Lee Moffitt Cancer Center [Member] \| Alliance Agreement [Member] \| Sales Based Milestones [Member]
Inflow From Issuance Of Intangible Asset
Other commitment			$ 50,000

Subsequent Events - Additional Information (Details) - Subsequent Event [Member] $ in Millions	Oct. 09, 2024 USD ($)
Subsequent Event [Line Items]
Percentage of workforce reduction	60.00%
Severance-related and employee benefits charges	$ 2.3

Fair Value of Financial Assets and Liabilities - Schedule of financial assets and liabilities measured on recurring basis at fair value (Detail) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Financial assets:
Total financial assets	$ 37,371	$ 92,730
Contingent consideration [Member]
Financial liabilities:
Total financial liabilities	866	916
Fair value recurring basis [Member]
Financial assets:
Money market funds	16,104	15,635
Restricted cash	116	116
U.S. government securities	21,151	76,979
Total financial assets	37,371	92,730
Financial liabilities:
Total financial liabilities	866	916
Fair value recurring basis [Member] \| Contingent consideration [Member]
Financial liabilities:
Contingent consideration	866	916
Fair value recurring basis [Member] \| Level 1 [Member]
Financial assets:
Money market funds	16,104	15,635
Restricted cash	116	116
U.S. government securities	21,151	76,979
Total financial assets	37,371	92,730
Fair value recurring basis [Member] \| Level 3 [Member]
Financial liabilities:
Total financial liabilities	866	916
Fair value recurring basis [Member] \| Level 3 [Member] \| Contingent consideration [Member]
Financial liabilities:
Contingent consideration	$ 866	$ 916

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Liabilities and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Accrued Liabilities and Other Liabilities [Abstract]
Research and development expense	$ 8,044	$ 5,675
Professional and consulting expense	760	641
Compensation	2,840	3,593
Total accrued expenses and other current liabilities	$ 11,644	$ 9,909

Agreements (Tables)

9 Months Ended

Sep. 30, 2024

Collaborative Arrangement Disclosure [Abstract]

Schedule Of Transaction Price Allocated To Programs Performance Obligation


Performance Obligations	Price Pre- Modification	Price at Modification
Development Program	$166.3 million	$134.3 million
Discovery Program	$26.3 million	$21.2 million
Total	$192.6 million	$155.5 million

Property and Equipment, Net

9 Months Ended

Sep. 30, 2024

Property, Plant and Equipment [Abstract]

Property and Equipment, Net

4. Property and Equipment, Net

Property and equipment, net consist of the following (in thousands):


	September 30,			December 31,
	2024			2023
Laboratory equipment	$	11,112		$	11,043
Furniture		690			690
Leasehold improvements		1,308			1,308
		13,110			13,041
Less accumulated depreciation and amortization		(8,033	)		(6,689	)
Total property and equipment, net	$	5,077		$	6,352

Property and equipment depreciation and amortization expense for the three months ended September 30, 2024 and 2023, was $0.5 million and $0.7 million, respectively and the nine months ended September 30, 2024 and 2023, was $1.5 million and $2.1 million, respectively.

Leases (Tables)

9 Months Ended

Sep. 30, 2024

Leases [Abstract]

Schedule of information about lease costs

The table below summarizes the Company’s total lease costs included in its unaudited condensed consolidated financial statements, as well as other required quantitative disclosures (in thousands):


	Three Months Ended September 30,						Nine Months Ended September 30,
	2024			2023			2024			2023
Operating lease cost	$	527		$	460		$	1,590		$	1,598
Short-term lease costs		—			—			—			1
Variable leases costs		—			—			—			5
Sublease income		(135	)		(130	)		(402	)		(368	)
Total lease cost	$	392		$	330		$	1,188		$	1,236

Schedule of present value of operating lease payments

The present value assumptions used in calculating the present value of the lease payments were as follows:


	Nine Months Ended
	September 30, 2024
Weighted-average remaining lease term in years		1.0
Weighted-average discount rate		5.75	%

Schedule of minimum aggregate future operating lease commitments

The minimum aggregate future operating lease commitments at September 30, 2024 are as follows (in thousands):


	Minimum Lease Payments
Remainder of 2024	$	528
2025		1,110
2026		104
2027		—
2028		—
2029		—
Total undiscounted lease payments	$	1,742
Less: imputed interest		(43	)
Total operating lease liability		1,699
Less: current portion of operating lease liability		(1,440	)
Operating lease liability, noncurrent	$	259

Redeemable Convertible Preferred Stock and Stockholders' Equity - Summary Of Shares Of Common Stock Reserved For Future Issuance (Detail) - shares	Sep. 30, 2024	Dec. 31, 2023
Class of Stock [Line Items]
Common stock reserved for future issuance	6,806,785	5,454,918
Employee Stock Option [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance	3,137,504	3,374,282
Unvested RSUs [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance	104,093	102,945
Shares available for issuance under the ESPP [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance	453,280	222,287
Shares available for issuance under the Plans [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance	3,111,908	1,755,404

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 505
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-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 272
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-Paragraph 3
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-URI https://asc.fasb.org/1943274/2147483014/272-10-45-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Net Loss per Share - Schedule of Dilutive Securities Excluded From Computation of Diluted Net Loss Per Share (Detail) - shares	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	3,332,337	2,769,278
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	90,740	181,480
Unvested RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	104,093
Options to purchase common stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	3,137,504	2,587,798

Legal Proceedings

9 Months Ended

Sep. 30, 2024

Commitments and Contingencies Disclosure [Abstract]

Legal Proceedings

14. Legal Proceedings

The Company is not a party to any material legal matters or claims and does not have contingency reserves established for any litigation liabilities as of September 30, 2024 and December 31, 2023.

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2024	Dec. 31, 2023
Preferred stock, par or stated value per Share	$ 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 or stated value per Share	$ 0.001	$ 0.001
Common stock, shares authorized	490,000,000	490,000,000
Common stock, shares, outstanding	23,128,454	23,099,335
Common stock, shares, issued	23,128,454	23,099,335

Equity Based Compensation - Summary of RSU Activity (Detail) - RSUs [Member] - $ / shares	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of Outstanding RSUs, Beginning balance	102,945
RSUs granted	16,384	0
RSUs Cancelled/Forfeited	(15,236)
Number of Outstanding RSUs, Ending balance	104,093
Weighted-Average Grant Date Fair Value, Beginning balance	$ 2.71
RSUs granted	2.75
RSUs Cancelled/Forfeited	2.71
Weighted-Average Grant Date Fair Value, Ending balance	$ 2.72

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Section 35
-Paragraph 1D
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Collaboration revenue				$ 19,306
Operating expenses:
Research and development	$ 14,424	$ 14,172	$ 47,944	47,033
General and administrative	3,944	4,758	13,172	13,449
Total operating expenses	18,368	18,930	61,116	60,482
Loss from operations	(18,368)	(18,930)	(61,116)	(41,176)
Other income, net	520	1,578	2,353	2,305
Net loss before income taxes	(17,848)	(17,352)	(58,763)	(38,871)
Benefit for income taxes	816	33	798	121
Net loss	(17,032)	(17,319)	(57,965)	(38,750)
Other comprehensive loss:
Unrealized gain (loss) on available-for-sale debt securities	30	(8)	(77)	172
Total comprehensive loss	(17,002)	(17,327)	(58,042)	(38,578)
Net loss	(17,032)	(17,319)	(57,965)	(38,750)
Less: accretion of preferred stock to redemption value				(39)
Net loss attributable to common stockholders, basic	(17,032)	(17,319)	(57,965)	(38,789)
Net loss attributable to common stockholders, diluted	$ (17,032)	$ (17,319)	$ (57,965)	$ (38,789)
Weighted-average number of shares of common stock outstanding, basic	23,037,714	17,397,845	23,029,106	7,730,694
Weighted-average number of shares of common stock outstanding, diluted	23,037,714	17,397,845	23,029,106	7,730,694
Net loss per share attributable to common stockholders, basic	$ (0.74)	$ (1)	$ (2.52)	$ (5.02)
Net loss per share attributable to common stockholders, diluted	$ (0.74)	$ (1)	$ (2.52)	$ (5.02)

Redeemable Convertible Preferred Stock and Stockholders' Equity - Additional Information (Detail) $ / shares in Units, $ / shares in Units, $ in Millions, $ in Millions	1 Months Ended				3 Months Ended	9 Months Ended	13 Months Ended
	Jun. 30, 2021 USD ($) $ / shares shares	Jan. 31, 2019 USD ($) $ / shares shares	Nov. 30, 2018 USD ($) $ / shares shares	Oct. 31, 2016 USD ($) shares	Sep. 30, 2023 shares	Sep. 30, 2024 $ / shares shares	Oct. 31, 2016 CAD ($) $ / shares shares	Oct. 31, 2016 USD ($) shares	Dec. 31, 2023 $ / shares shares	Aug. 15, 2023 $ / shares	Jul. 25, 2023 $ / shares shares	Oct. 31, 2016 $ / shares
Class of Stock [Line Items]
Shares issued, price per share \| $ / shares										$ 12
Common stock, par or stated value per Share \| $ / shares						$ 0.001			$ 0.001		$ 0.001
Common stock, shares authorized						490,000,000			490,000,000		490,000,000
Common Stock [Member]
Class of Stock [Line Items]
Conversion of redeemable convertible preferred stock into common stock					12,493,879	12,493,879
Series A Redeemable Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Number of stock classified as temporary equity issued during the period							11,250,000	11,250,000
Shares issued, price per share \| (per share)							$ 1					$ 0.74
Foreign exchange rate							1.344					1.344
Value of new stock classified as temporary equity issued during the period							$ 10.9	$ 8.1
Series B1 Redeemable Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Number of stock classified as temporary equity issued during the period				16,285,156
Shares issued, price per share \| $ / shares												$ 0.77
Proceeds from Issuance of redeemable convertible preferred stock \| $				$ 12.3
Series B2 Redeemable Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Number of stock classified as temporary equity issued during the period			25,065,538
Shares issued, price per share \| $ / shares			$ 1.15
Proceeds from Issuance of redeemable convertible preferred stock \| $			$ 28.9
Series C Redeemable Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Number of stock classified as temporary equity issued during the period		17,905,288
Shares issued, price per share \| $ / shares		$ 2.35
Proceeds from Issuance of redeemable convertible preferred stock \| $		$ 41.8
Series D Redeemable Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Number of stock classified as temporary equity issued during the period	29,285,356
Shares issued, price per share \| $ / shares	$ 2.73
Proceeds from Issuance of redeemable convertible preferred stock \| $	$ 79.8

Net Loss per Share (Tables)

9 Months Ended

Sep. 30, 2024

Earnings Per Share [Abstract]

Schedule of dilutive securities excluded from computation of diluted net loss per share

The following outstanding potentially dilutive shares were excluded from the computation of diluted net loss per share attributable to common stockholders:


	Nine Months Ended September 30,
	2024		2023
Restricted stock		90,740		181,480
Unvested RSUs		104,093		—
Options to purchase common stock		3,137,504		2,587,798
Total		3,332,337		2,769,278

Fair Value of Financial Assets and Liabilities - Schedule of company's contingent consideration measured at fair value level 3 (Detail) - Contingent consideration [Member] $ in Thousands	9 Months Ended
	Sep. 30, 2024 USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 916
Changes in the fair value of contingent consideration	(49)
Ending balance	$ 866

Equity Based Compensation - Schedule of Fair Value Assumption of Stock Option Activity (Detail) - $ / shares	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Schedule Of Share Based Payment Award Stock Options Valuation Assumptions [Line Items]
Risk-free interest rate, Minimum	4.30%	3.89%
Risk-free interest rate, Maximum	4.72%	4.59%
Dividend yield	0.00%	0.00%
Volatility, Minimum	94.00%	85.80%
Volatility, Maximum	94.70%	87.30%
Minimum [Member]
Schedule Of Share Based Payment Award Stock Options Valuation Assumptions [Line Items]
Expected term (in years)	5 years 10 months 17 days	6 years 25 days
Exercise price of stock options granted	$ 2.68	$ 9.22
Maximum [Member]
Schedule Of Share Based Payment Award Stock Options Valuation Assumptions [Line Items]
Expected term (in years)	6 years 10 days	6 years 2 months 12 days
Exercise price of stock options granted	$ 2.88	$ 16.53

Cover Page - shares	9 Months Ended
Cover Page - shares	Sep. 30, 2024	Nov. 10, 2024
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Amendment Flag	false
Document Period End Date	Sep. 30, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Entity Registrant Name	Turnstone Biologics Corp.
Entity Central Index Key	0001764974
Entity File Number	001-41747
Entity Tax Identification Number	83-2909368
Entity Incorporation, State or Country Code	DE
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Address, Address Line One	9310 Athena Circle
Entity Address, Address Line Two	Suite 300
Entity Address, City or Town	La Jolla
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92037
City Area Code	347
Local Phone Number	897-5988
Title of 12(b) Security	Common Stock ($0.001 par value)
Trading Symbol	TSBX
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding		23,128,454

Leases

9 Months Ended

Sep. 30, 2024

Leases [Abstract]

Leases

12. Leases

Operating Leases

The Company leases laboratory and office space for its corporate headquarters located in San Diego, California and office space in New York, New York and Ontario, Canada. Operating lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term. In calculating the present value of the lease payments, the Company has elected to utilize its incremental borrowing rate based on the original lease term and not the remaining lease term. The Company determines if an arrangement is a lease by considering whether there is an identified asset, and the contract conveys the right to control its use. Leases with an initial term of 12 months or less are not recorded on the balance sheet. The Company’s lease terms may include options to extend or terminate a lease. If the lease includes non-lease components (i.e., common area maintenance) that are paid separately from rent based on actual costs incurred and therefore are not included in the right-of-use asset and lease liability but are reflected as an expense in the period incurred.

In July 2018, the Company entered into a lease agreement for approximately 6,500 square feet of office space in New York, New York. The term of the lease is seven years and three months, starting November 1, 2018. The lease requires the Company to share in prorated expenses and property taxes based upon actual amounts incurred. The lease contains escalating rent clauses which require higher rent payments in future years. In September 2022, the Company made the decision to sublease this space and executed a sublease in November 2022 for the remaining term of the lease. Since the Company is still responsible for making the lease payments, there was no impact to the operating lease liability from the sublease. However, since the sublease payment does not cover the entire lease payment, the carrying value of the operating right of use asset was analyzed and determined to be impaired resulting in a $0.5 million reduction in the operating right of use asset in September 2022.

In January 2019, the Company executed an agreement to lease approximately 6,000 square feet of laboratory space at Carleton University in Ontario, Canada. The initial term of the lease is three years and started in November 2019 at a rate of approximately $0.1 million per year. In November 2022, the lease was extended for a one year period. In August 2023, the Company terminated the lease.

In May 2019, the Company entered into a noncancelable operating lease for approximately 9,423 square feet located at 12 York Street, Ontario, Canada. The term of the lease is five years, starting December 1, 2019, and includes one renewal option for a period of five years. The lease requires the Company to share in prorated expenses and property taxes based upon actual amounts incurred. The lease contains escalating rent clauses which require higher rent payments in future years.

In June 2021, the Company entered into a lease agreement for approximately 19,474 square feet of office and laboratory space in San Diego, California. The initial term of the lease is 38 months with one renewal option for a period of three years and commenced in March 2022. The lease requires the Company to share in prorated expenses and property taxes based upon actual amounts incurred. The lease contains escalating rent clauses which require higher rent payments in future years.

The Company recorded rent expense of $0.8 million and $1.2 million for the nine months ended September 30, 2024 and 2023, respectively. The table below summarizes the Company’s total lease costs included in its unaudited condensed consolidated financial statements, as well as other required quantitative disclosures (in thousands):


	Three Months Ended September 30,						Nine Months Ended September 30,
	2024			2023			2024			2023
Operating lease cost	$	527		$	460		$	1,590		$	1,598
Short-term lease costs		—			—			—			1
Variable leases costs		—			—			—			5
Sublease income		(135	)		(130	)		(402	)		(368	)
Total lease cost	$	392		$	330		$	1,188		$	1,236

The present value assumptions used in calculating the present value of the lease payments were as follows:


	Nine Months Ended
	September 30, 2024
Weighted-average remaining lease term in years		1.0
Weighted-average discount rate		5.75	%

The minimum aggregate future operating lease commitments at September 30, 2024 are as follows (in thousands):


	Minimum Lease Payments
Remainder of 2024	$	528
2025		1,110
2026		104
2027		—
2028		—
2029		—
Total undiscounted lease payments	$	1,742
Less: imputed interest		(43	)
Total operating lease liability		1,699
Less: current portion of operating lease liability		(1,440	)
Operating lease liability, noncurrent	$	259

Term Loan

9 Months Ended

Sep. 30, 2024

Debt Disclosure [Abstract]

Term Loan

8. Term Loan

On April 26, 2024 (the "Closing Date"), the Company entered into the LSA, by and among the Company, as borrower, the Company’s wholly owned subsidiary, Myst Therapeutics, LLC (“Myst LLC” and, together with the Company, the “Loan Parties”) and BOC, as lender. The LSA provides for a revolving credit facility in an aggregate principal amount of up to $20.0 million (the “Revolving Loans”). The Company may request advances at any time the loan is not in default and not to exceed the Revolving Loans limit and may prepay any amounts outstanding at any time with no prepayment penalty. Upon termination of the LSA, whether in connection with acceleration, prepayment in full, or otherwise, the Company is obligated to make a nonrefundable payment of (i) $0.4 million at any time on or prior to the first anniversary of the Closing Date, and (ii) $0.2 million at any time after the first anniversary of the Closing Date but prior to the second anniversary. In addition, the Company is obligated to pay a fee in the event of certain corporate transactions equal to the greater of (i) $50,000 or (ii) 2% of the highest aggregate principal amount outstanding prior to the transaction (the "Success Fee"). The Success Fee is due upon any merger or consolidation, any sale of substantially all of the assets of the Company, or the closing of one or more related financings where aggregate cash proceeds from the sale of equity securities and/or upfront cash proceeds from strategic partnerships is equal to at least $75.0 million and occurs on or before the tenth anniversary of the Closing Date (each a "Success Fee Event"). If the LSA is terminated prior to the payment of the Success Fee, the Company will remain obligated to pay the Success Fee upon the occurrence of a Success Fee Event during such ten-year period.

The annual interest rate applicable to the Revolving Loans is the greater of the Prime Rate (as defined in the LSA) and 4.25%. Interest under the Revolving Loans is due and payable on the first calendar day of month during the term. The initial maturity date of the Revolving Loans is March 31, 2026, which may be extended to March 31, 2027 subject to the satisfaction of certain terms and conditions as set forth in the LSA. Upon maturity, all amounts outstanding will become due and payable.

The LSA contains customary representations and warranties and customary affirmative and negative covenants, including, among other things, restrictions on indebtedness, liens, investments, mergers, dispositions, prepayment of other indebtedness and dividends and other distributions. The Company is also required to comply with certain covenants requiring the Company to (i) receive positive interim Phase 1 data for TIDAL-01 (as determined by the Company’s board of directors), which was satisfied in August 2024 and (ii) receive at least $40.0 million in new funding from the sale of equity, partnerships, and/or business development payments, in each case, by March 31, 2025. If the Company fails to comply with any of the foregoing covenants, the Lender may terminate the commitments to make further loans and declare all of the obligations of the Company under the LSA to be immediately due and payable.

The LSA also includes customary events of default, including failure to pay principal, interest or certain other amounts when due, material inaccuracy of representations and warranties, violation of covenants, specified cross-default and cross-acceleration to

other material indebtedness, certain bankruptcy and insolvency events, certain undischarged judgments, material invalidity of guarantees or grant of security interest, material adverse effect and change of control, in certain cases subject to certain thresholds and grace periods. If one or more events of default occurs and continues beyond any applicable cure period, the Lender may terminate the commitments to make further loans and declare all of the obligations of the Company under the LSA to be immediately due and payable. Additionally, upon the occurrence of an event of default, the Company is obligated to pay a fee equal to 3.0% above the interest rate then in effect on all outstanding obligations.

As of September 30, 2024, no amounts had been drawn under the Revolving Loans.

The Company incurred $0.1 of debt issuance costs which were recorded as part of Other Current Assets and will be amortized over the term of the LSA.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

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+ Details

Subsequent Events

9 Months Ended

Sep. 30, 2024

Subsequent Events [Abstract]

Subsequent Events

15. Subsequent Events

On October 9, 2024, the Board of Directors of the Company approved a strategic prioritization of the Company's pipeline as well as a workforce reduction of approximately 60% to focus resources on the continued advancement of TIDAL-01. The workforce reduction is expected to be substantially completed in the fourth quarter of 2024. The Company anticipates a one-time severance-related charge associated with the workforce reduction to be approximately $2.3 million, which represents cash expenditures related to employee severance and notice period payments, benefits and related costs. The Company may also incur other charges or cash expenditures not currently contemplated due to events that may occur as a result of, or associated with, this reduction in workforce.

Leases - Schedule of Information about Lease Costs (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Lease, Cost [Abstract]
Operating lease cost	$ 527	$ 460	$ 1,590	$ 1,598
Short-term lease costs				1
Variable leases costs				5
Sublease income	(135)	(130)	(402)	(368)
Total lease cost	$ 392	$ 330	$ 1,188	$ 1,236

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (17,032)	$ (21,304)	$ (19,629)	$ (17,319)	$ (21,499)	$ 68	$ (57,965)	$ (38,750)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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-Subparagraph (SX 210.13-02(a)(4)(iii)(A))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1B

Reference 29: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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-Name Accounting Standards Codification
-Section S99
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1B

Reference 30: http://www.xbrl.org/2003/role/disclosureRef
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-Section S99
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Reference 31: http://www.xbrl.org/2003/role/disclosureRef
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Reference 32: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 10
-Name Accounting Standards Codification
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-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482689/260-10-45-60B

Reference 33: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483499/205-20-50-7

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-Name Accounting Standards Codification
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-Paragraph 28
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-28

Reference 35: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1A
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482790/220-10-45-1A

Reference 36: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
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-Section 45
-Paragraph 1B
-Subparagraph (a)
-Publisher FASB
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Reference 37: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(22))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1

+ Details

Equity Based Compensation - Schedule of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Schedule Of Share Based Compensation Stock Options Activity [Line Items]
Number of Shares Underlying Outstanding Options, Beginning balance	3,374,282	2,529,982	2,529,982
Options granted	129,165	231,662
Options exercised	(29,119)	(23,455)
Options canceled/forfeited	(336,824)	(150,391)
Number of Shares Underlying Outstanding Options, Ending balance	3,137,504	2,587,798	3,374,282	2,529,982
Exercisable		1,711,392
Vested and expected to vest	3,137,504	2,587,798
Weighted- Average Exercise Price Outstanding	$ 7.66	$ 8.86	$ 8.86
Options granted	2.73	15.12
Options exercised	1.51	4.02
Options canceled/forfeited	6.67	10.69
Weighted- Average Exercise Price Outstanding	7.62	9.35	$ 7.66	$ 8.86
Exercisable		7.99
Vested and expected to vest	$ 7.62	$ 9.35
Weighted- Average Remaining Contractual Term (Years) Outstanding	6 years 1 month 6 days	6 years 6 months	7 years 1 month 6 days	6 years 9 months 18 days
Exercisable		5 years 4 months 24 days
Vested and expected to vest	6 years 1 month 6 days	6 years 6 months
Aggregate Intrinsic Value Outstanding , Beginning balance	$ 352	$ 6,912	$ 6,912
Aggregate Intrinsic Value Outstanding , Ending balance		848	$ 352	$ 6,912
Exercisable		848
Vested and expected to vest		$ 848

Leases - Schedule of Present Value of Operating Lease Payments (Detail)	Sep. 30, 2024
Schedule of Present Value of Operating Lease Payments [Abstract]
Weighted-average remaining lease term in years	1 year
Weighted-average discount rate	5.75%

Asset Acquisition - Additional Information (Detail) - USD ($) $ in Thousands					1 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 11, 2023	Jun. 14, 2022	Jun. 08, 2022	Dec. 15, 2020	Jan. 31, 2023	Jul. 31, 2022	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2020	Jul. 25, 2023	Jan. 10, 2023	Jul. 28, 2022	Jul. 25, 2022	May 31, 2022
Asset Acquisition [Line Items]
Payment for contingent consideration liability										$ 898
Third Milestone Payment [Member]
Asset Acquisition [Line Items]
Contingent consideration payable				$ 20,000
Langer [Member] \| Initial Milestone Payment [Member]
Asset Acquisition [Line Items]
Contingent consideration payable by shares								$ 2,800		2,800
Stock issued during the period for milestone payments shares	249,992
Langer [Member] \| Second Milestone Payment [Member]
Asset Acquisition [Line Items]
Contingent consideration payable															$ 9,400
Contingent consideration payable by shares						$ 5,000
Contingent consideration payable by cash													$ 2,200	$ 2,200
Stock issued during the period for milestone payments shares			212,203
Stock issued during the period for milestone payments value			$ 5,000
Payment for contingent consideration liability					$ 2,200	2,200
Myst Holders [Member] \| Initial Milestone Payment [Member]
Asset Acquisition [Line Items]
Contingent consideration payable	$ 3,000
Myst Holders [Member] \| Second Milestone Payment [Member]
Asset Acquisition [Line Items]
Contingent consideration payable															10,000	$ 10,000
Contingent consideration payable by shares																5,000
Contingent consideration payable by cash																$ 5,000
Payment for contingent consideration liability						2,800
Remaining Myst Holders [Member] \| Initial Milestone Payment [Member]
Asset Acquisition [Line Items]
Contingent consideration payable by cash								200		200
Remaining Myst Holders [Member] \| Second Milestone Payment [Member]
Asset Acquisition [Line Items]
Contingent consideration payable by cash															$ 600
Payment for contingent consideration liability						$ 600
Myst Merger Agreement [Member]
Asset Acquisition [Line Items]
Payments to acquire productive assets		$ 1,000		9,000
Research and development asset acquired other than through business combination, write-off											$ 19,400
Research and Development Asset Acquired in Transaction Other than Business Combination or Joint Venture Formation, Writeoff, Statement of Income or Comprehensive Income [Extensible Enumeration]											Nonoperating Income (Expense)
Asset acquisition contingent consideration arrangements change in amount of contingent consideration, liability							$ 200	$ 800	$ 100	$ 1,700
Myst Merger Agreement [Member] \| Initial Milestone Payment [Member]
Asset Acquisition [Line Items]
Contingent consideration, liability												$ 3,000
Myst Merger Agreement [Member] \| Second Milestone Payment [Member]
Asset Acquisition [Line Items]
Contingent consideration payable				$ 10,000
Myst Merger Agreement [Member] \| Langer [Member]
Asset Acquisition [Line Items]
Asset acquisition, consideration transferred, equity interest issued and issuable shares		725,920
Asset acquisition consideration transferred equity interest issued shares		362,960
Asset acquisition consideration transferred equity interest issuable shares		362,960
Myst Merger Agreement [Member] \| Langer [Member] \| Restricted Stock [Member]
Asset Acquisition [Line Items]
Percentage of vesting of award under share-based payment arrangement		25.00%
Number of equity-based payment instruments vested during the period									272,220
Number of non-vested equity-based payment instruments							90,740		90,740

Fair Value of Financial Assets and Liabilities - Schedule of unobservable input of contingent consideration valuation (Detail) - Contingent consideration [Member] $ in Thousands	Sep. 30, 2024 USD ($) yr	Dec. 31, 2023 USD ($) yr
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of financial liabilities \| $	$ 866	$ 916
Measurement input likelihood of occurrence [Member] \| Valuation technique discounted cash flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration input range	10	10
Measurement input discount rate [Member] \| Valuation technique discounted cash flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration input range	25	25
Measurement input expected term [Member] \| Valuation technique discounted cash flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration input range \| yr	3.8	3.5

Nature of the Business and Basis of Presentation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands				3 Months Ended						9 Months Ended
	Sep. 27, 2024	Aug. 15, 2023	Jul. 25, 2023	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023	Mar. 31, 2025	Apr. 26, 2024	Dec. 31, 2023
Business Description And Basis Of Presentation [Line Items]
Description of the reverse stock split arrangement			1-for-7.9872
Number of new stock issued during the period		651,608
Shares issued, price per share		$ 12
Cash received on stock transaction after deduction of issuance costs		$ 7,300
Underwriting discounts and commissions		$ 500
Shares authorized			500,000,000
Common stock, shares authorized			490,000,000	490,000,000						490,000,000				490,000,000
Number of business days	30 days
Preferred stock, shares authorized			10,000,000	10,000,000						10,000,000				10,000,000
Common stock par value			$ 0.001	$ 0.001						$ 0.001				$ 0.001
Preferred stock par value			$ 0.001	$ 0.001						$ 0.001				$ 0.001
Net Income (Loss)				$ (17,032)	$ (21,304)	$ (19,629)	$ (17,319)	$ (21,499)	$ 68	$ (57,965)	$ (38,750)
Accumulated deficit				$ 234,723						$ 234,723				$ 176,758
Common Stock [Member]
Business Description And Basis Of Presentation [Line Items]
Number of new stock issued during the period							7,318,275
Revolving Loans [Member]
Business Description And Basis Of Presentation [Line Items]
Revolving credit facility, aggregate principal amount													$ 20,000
Interest rate percentage													4.25%
Maximum [Member] \| Common Stock [Member]
Business Description And Basis Of Presentation [Line Items]
Bid price per share	$ 1
IPO [Member]
Business Description And Basis Of Presentation [Line Items]
Number of new stock issued during the period			6,666,667
Shares issued, price per share			$ 12
Cash received on stock transaction after deduction of issuance costs			$ 68,700
Underwriting discounts and commissions			5,600
Other offering expenses			$ 5,700
Forecast [Member] \| Minimum [Member]
Business Description And Basis Of Presentation [Line Items]
Funding from sale of equity partnerships and or business development payments												$ 40,000

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 24,133	$ 17,798
Restricted cash	116	116
Short-term investments	21,151	76,979
Accounts receivable - collaboration agreement	0	194
Prepaid expenses	3,712	4,655
Other current assets	2,031	2,812
Total current assets	51,143	102,554
Other assets, noncurrent	873	1,143
Operating lease right of use assets	1,391	2,766
Property and equipment, net	5,077	6,352
Total assets	58,484	112,815
Current liabilities:
Accounts payable	560	36
Accrued expenses and other current liabilities	11,644	9,909
Operating lease liability, current	1,440	2,025
Total current liabilities	13,644	11,970
Operating lease liability, noncurrent	259	1,189
Other liabilities, noncurrent	940	989
Total liabilities	14,843	14,148
Stockholders' equity (deficit)
Preferred stock, $0.001 par value; 10,000,000 shares authorized, at September 30, 2024 and December 31, 2023, respectively, 0 shares issued and outstanding as of September 30, 2024 and December 31, 2023, respectively	0	0
Common stock, $0.001 par value; 490,000,000 shares authorized at September 30, 2024 and December 31, 2023, respectively, 23,128,454 and 23,099,335 shares issued and outstanding as of September 30, 2024 and December 31, 2023, respectively	23	23
Additional paid-in capital	278,537	275,521
Accumulated other comprehensive loss	(196)	(119)
Accumulated deficit	(234,723)	(176,758)
Total stockholders' equity	43,641	98,667
Total liabilities and stockholders' equity	$ 58,484	$ 112,815

Agreements - Schedule Of Transaction Price Allocated To Programs Performance Obligation (Detail) $ in Millions	Jun. 30, 2022 USD ($)
Price Pre-Modification [Member]
Schedule Of Transaction Price Allocatied To Programs Performance Obligation [Line Items]
Performance Obligations	$ 192.6
Price at Modification [Member]
Schedule Of Transaction Price Allocatied To Programs Performance Obligation [Line Items]
Performance Obligations	155.5
Development Program [Member] \| Price Pre-Modification [Member]
Schedule Of Transaction Price Allocatied To Programs Performance Obligation [Line Items]
Performance Obligations	166.3
Development Program [Member] \| Price at Modification [Member]
Schedule Of Transaction Price Allocatied To Programs Performance Obligation [Line Items]
Performance Obligations	134.3
Discovery Program [Member] \| Price Pre-Modification [Member]
Schedule Of Transaction Price Allocatied To Programs Performance Obligation [Line Items]
Performance Obligations	26.3
Discovery Program [Member] \| Price at Modification [Member]
Schedule Of Transaction Price Allocatied To Programs Performance Obligation [Line Items]
Performance Obligations	$ 21.2

Fair Value of Financial Assets and Liabilities - Schedule of company's cash, cash equivalents and available-for-sale securities (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Fair Value Disclosures [Line Items]
Amortized cost	$ 37,365	$ 92,626
Gross unrealized gains		104
Gross unrealized losses	(6)
Estimated fair value	37,371	92,730
Money market funds [Member] \| Level 1 [Member]
Fair Value Disclosures [Line Items]
Amortized cost	16,104	15,635
Estimated fair value	16,104	15,635
Restricted cash [Member]
Fair Value Disclosures [Line Items]
Estimated fair value	116	116
Restricted cash [Member] \| Level 1 [Member]
Fair Value Disclosures [Line Items]
Amortized cost	116	116
Estimated fair value	116	116
U.S. government and agency securities [Member] \| Level 1 [Member]
Fair Value Disclosures [Line Items]
Amortized cost	21,145	76,875
Gross unrealized gains		104
Gross unrealized losses	(6)
Estimated fair value	21,151	76,979
Cash and cash equivalents [Member]
Fair Value Disclosures [Line Items]
Estimated fair value	16,104	15,635
Short-term investments [Member]
Fair Value Disclosures [Line Items]
Estimated fair value	$ 21,151	$ 76,979

Term Loan - Additional Information (Details) - USD ($)	Apr. 26, 2024	Mar. 31, 2025	Sep. 30, 2024
Minimum [Member] \| Forecast [Member]
Line of Credit Facility [Line Items]
Funding from sale of equity partnerships and or business development payments		$ 40,000,000
Revolving Loans [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, aggregate principal amount	$ 20,000,000
Debt instrument nonrefundable prepayment fee	400,000
Debt instrument nonrefundable prepayment fee in first anniversary	200,000
Debt instrument success fee amount	$ 50,000
Debt instrument success fee percentage	2.00%
Interest rate description	The annual interest rate applicable to the Revolving Loans is the greater of the Prime Rate (as defined in the LSA) and 4.25%.
Interest rate percentage	4.25%
Debt instrument, fee on the event of default	3.00%
Line of credit maturity date	Mar. 31, 2026
Line of credit facility extended date	Mar. 31, 2027
Amounts drawn and outstanding under credit facility			$ 0
Debt issuance costs			$ 0.1
Revolving Loans [Member] \| Minimum [Member]
Line of Credit Facility [Line Items]
Cash Proceeds From The Sale of Equity Securities And/Or Upfront Cash Proceeds From Strategic Partnerships	$ 75,000,000

Accrued Expenses and Other Current Liabilities

9 Months Ended

Sep. 30, 2024

Accrued Liabilities and Other Liabilities [Abstract]

Accrued Expenses and Other Current Liabilities

5. Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consist of the following (in thousands):


	September 30,		December 31,
	2024		2023
Research and development expense	$	8,044	$	5,675
Professional and consulting expense		760		641
Compensation		2,840		3,593
Total accrued expenses and other current liabilities	$	11,644	$	9,909

Equity Based Compensation - Schedule of Stock Based Compensation for Stock Awards (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation	$ 907	$ 1,064	$ 2,972	$ 3,130
Research and development [Member]
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation	522	631	1,816	1,640
General and administrative [Member]
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation	$ 385	$ 433	$ 1,156	$ 1,490

Leases - Schedule of Minimum Aggregate Future Operating Lease Commitments (Detail) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Lessee, Operating Lease, Liability, to be Paid, Fiscal Year Maturity [Abstract]
Remainder of 2024	$ 528
2025	1,110
2026	104
2027	0
2028	0
2029	0
Total undiscounted lease payments	1,742
Less: imputed interest	(43)
Total operating lease liability	1,699
Less: current portion of operating lease liability	(1,440)	$ (2,025)
Operating lease liability, noncurrent	$ 259	$ 1,189

Property and Equipment, Net (Tables)

9 Months Ended

Sep. 30, 2024

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment Net

Property and equipment, net consist of the following (in thousands):


	September 30,			December 31,
	2024			2023
Laboratory equipment	$	11,112		$	11,043
Furniture		690			690
Leasehold improvements		1,308			1,308
		13,110			13,041
Less accumulated depreciation and amortization		(8,033	)		(6,689	)
Total property and equipment, net	$	5,077		$	6,352

Fair Value of Financial Assets and Liabilities - Additional Information (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024 USD ($) Security	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) Security	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($) Security
Fair Value Disclosures [Line Items]
Asset impairment charges	$ 0	$ 0	$ 0	$ 0
Investment, Type [Extensible Enumeration]	Short-Term Investments [Member]	Short-Term Investments [Member]	Short-Term Investments [Member]	Short-Term Investments [Member]
Available-for-sale debt securities an aggregate fair value	$ 21,200		$ 21,200
Maximum [Member]
Fair Value Disclosures [Line Items]
Number of available-for-sale debt securities in gross unrealized loss position \| Security	7		7		28
Minimum [Member]
Fair Value Disclosures [Line Items]
Number of available-for-sale debt securities in gross unrealized loss position \| Security	0		0		0
Myst [Member]
Fair Value Disclosures [Line Items]
Contingent consideration liability	$ 900		$ 900		$ 900

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 103
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-103

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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-Name Accounting Standards Codification
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479130/326-30-45-1

+ Details

- Definition

Indicates type of investment. Includes, but is not limited to, common stock, preferred stock, convertible security, fixed income security, government security, option purchased, warrant, loan participation and assignment, commercial paper, bankers' acceptance, certificates of deposit, short-term security, repurchase agreement, and other investment company.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Property and Equipment, Net - Schedule of Property and Equipment, Net Consist (Detail) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Laboratory equipment	$ 11,112	$ 11,043
Furniture	690	690
Leasehold improvements	1,308	1,308
Property plant and equipment gross	13,110	13,041
Less accumulated depreciation and amortization	(8,033)	(6,689)
Total property and equipment, net	$ 5,077	$ 6,352

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Sep. 30, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Fair Value of Financial Assets and Liabilities (Tables)

9 Months Ended

Sep. 30, 2024

Fair Value Disclosures [Abstract]

Schedule of Financial Assets and Liabilities Measured on Recurring Basis at Fair Value

The following tables represent a summary of the financial assets and liabilities that are measured on a recurring basis at fair value (in thousands):


	September 30, 2024
	Level 1		Level 2		Level 3		Fair Value
Financial assets:
Money market funds	$	16,104	$	—	$	—	$	16,104
Restricted cash(1)		116		—		—		116
U.S. government securities(2)		21,151		—		—		21,151
Total financial assets	$	37,371	$	—	$	—	$	37,371
Financial liabilities:
Contingent consideration(3)	$	—	$	—	$	866	$	866
Total financial liabilities	$	—	$	—	$	866	$	866


	December 31, 2023
	Level 1		Level 2		Level 3		Fair Value
Financial assets:
Money market funds	$	15,635	$	—	$	—	$	15,635
Restricted cash(1)		116		—		—		116
U.S. government securities(2)		76,979		—		—		76,979
Total financial assets	$	92,730	$	—	$	—	$	92,730
Financial liabilities:
Contingent consideration(3)	$	—	$	—	$	916	$	916
Total financial liabilities	$	—	$	—	$	916	$	916

(1)

Restricted cash serves as deposits for the Company’s San Diego office lease.

(2)

Included in short-term investments on the unaudited condensed consolidated balance sheets and are classified as available-for sale debt securities.

(3)

Contingent consideration related to the Myst Merger Agreement.

Schedule of Unobservable Input of Contingent Consideration Valuation

The following significant unobservable inputs were used in the valuation of the contingent consideration payable to the sole common stockholder of Myst Therapeutics, Inc. ("Myst") pursuant to the Myst Merger Agreement:


	Fair Value as of
Contingent Consideration Liability	September 30, 2024		Valuation Technique	Unobservable Input	Amount
	(in thousands)
Milestone payment for first registrational study (see Note 7 - Asset Acquisition for additional information)	$	866	Discounted cash flow	Likelihood of occurrence	10%
				Discount rate	25%
				Expected term (in years)	3.8

	Fair Value as of
Contingent Consideration Liability	December 31, 2023		Valuation Technique	Unobservable Input	Amount
	(in thousands)
Milestone payment for first registrational study (see Note 7 - Asset Acquisition for additional information)	$	916	Discounted cash flow	Likelihood of occurrence	10%
				Discount rate	25%
				Expected term (in years)	3.5

Schedule of Company's Contingent Consideration Measured at Fair Value Level 3

The following table reflects the activity for the Company’s contingent consideration, measured at fair value using Level 3 inputs (in thousands):


Contingent consideration at December 31, 2023	$	916
Changes in the fair value of contingent consideration		(49	)
Contingent consideration at September 30, 2024	$	866

Schedule of Company's Cash, Cash Equivalents and Available-for-Sale Securities

The following tables show the Company’s cash, cash equivalents and available-for-sale securities by significant investment category (in thousands):


	September 30, 2024
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Level 1: Money market funds	$	16,104	$	—	$	—	$	16,104
Restricted cash		116		—		—		116
U.S. government securities		21,145		—		6		21,151
Total financial assets	$	37,365	$	—	$	6	$	37,371
Classified as:
Cash and cash equivalents							$	16,104
Restricted cash								116
Short-term investments								21,151
							$	37,371


	December 31, 2023
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Level 1: Money market funds	$	15,635	$	—	$	—	$	15,635
Restricted cash		116		—		—		116
U.S. government securities		76,875		104		—		76,979
Total financial assets	$	92,626	$	104	$	—	$	92,730
Classified as:
Cash and cash equivalents							$	15,635
Restricted cash								116
Short-term investments								76,979
							$	92,730

Income Taxes

9 Months Ended

Sep. 30, 2024

Income Tax Disclosure [Abstract]

Income taxes

11. Income Taxes

The Company did not record federal income tax expense for the nine months ended September 30, 2024 and 2023, respectively, as the Company expects to be in a cumulative taxable loss position in 2024 and 2023, and the net deferred tax assets are fully offset by a valuation allowance as it is not more likely than not that the benefit will be realized. The Company recorded a benefit (provision) for state income taxes of $0.0 million and $0.1 million for the nine months ended September 30, 2024 and 2023, respectively.

- Definition

The entire disclosure for income tax.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-12

Reference 2: http://www.xbrl.org/2003/role/exampleRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482603/740-30-50-2

+ Details

Redeemable Convertible Preferred Stock and Stockholders' Equity (Tables)

9 Months Ended

Sep. 30, 2024

Stockholders' Equity Note [Abstract]

Summary of shares of common stock reserved for future issuance

Shares of common stock reserved for future issuance consisted of the following:


	September 30,		December 31,
	2024		2023
Common stock options outstanding		3,137,504		3,374,282
Unvested RSUs		104,093		102,945
Shares available for issuance under the ESPP		453,280		222,287
Shares available for issuance under the Plans		3,111,908		1,755,404
		6,806,785		5,454,918

Condensed Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]	Series A redeemable convertible preferred stock [Member] Preferred Stock [Member]	Series B-1 Redeemable Convertible Preferred Stock [Member] Preferred Stock [Member]	Series B-2 Redeemable Convertible Preferred Stock [Member] Preferred Stock [Member]	Series C redeemable convertible preferred stock [Member] Preferred Stock [Member]	Series D redeemable convertible preferred stock [Member] Preferred Stock [Member]
Beginning balance (in shares) at Dec. 31, 2022						11,250,000	16,285,156	25,065,538	17,905,288	29,285,356
Beginning balance at Dec. 31, 2022						$ 8,643	$ 12,611	$ 28,860	$ 42,100	$ 79,730
Beginning balance (in shares) at Dec. 31, 2022		2,915,757
Beginning balance at Dec. 31, 2022	$ (101,467)	$ 3	$ 20,501	$ (413)	$ (121,558)
Accretion of redeemable convertible preferred stock issuance costs										$ 20
Accretion of redeemable convertible preferred stock issuance costs	(20)		(20)
Moffitt performance based common stock award (in shares)		91,721
Exercise of stock options (in shares)		20,658
Exercise of stock options	83		83
Stock-based compensation expense	992		992
Unrealized gain (loss) on available-for-sale debt securities	121			121
Net Income (Loss)	68				68
Ending balance (in shares) at Mar. 31, 2023						11,250,000	16,285,156	25,065,538	17,905,288	29,285,356
Ending balance at Mar. 31, 2023						$ 8,643	$ 12,611	$ 28,860	$ 42,100	$ 79,750
Ending balance (in shares) at Mar. 31, 2023		3,028,136
Ending balance at Mar. 31, 2023	(100,223)	$ 3	21,556	(292)	(121,490)
Beginning balance (in shares) at Dec. 31, 2022						11,250,000	16,285,156	25,065,538	17,905,288	29,285,356
Beginning balance at Dec. 31, 2022						$ 8,643	$ 12,611	$ 28,860	$ 42,100	$ 79,730
Beginning balance (in shares) at Dec. 31, 2022		2,915,757
Beginning balance at Dec. 31, 2022	$ (101,467)	$ 3	20,501	(413)	(121,558)
Exercise of stock options (in shares)	23,455
Unrealized gain (loss) on available-for-sale debt securities	$ 172
Net Income (Loss)	(38,750)
Ending balance (in shares) at Sep. 30, 2023		23,093,075
Ending balance at Sep. 30, 2023	113,899	$ 23	274,425	(241)	(160,308)
Beginning balance (in shares) at Mar. 31, 2023						11,250,000	16,285,156	25,065,538	17,905,288	29,285,356
Beginning balance at Mar. 31, 2023						$ 8,643	$ 12,611	$ 28,860	$ 42,100	$ 79,750
Beginning balance (in shares) at Mar. 31, 2023		3,028,136
Beginning balance at Mar. 31, 2023	(100,223)	$ 3	21,556	(292)	(121,490)
Accretion of redeemable convertible preferred stock issuance costs										$ 19
Accretion of redeemable convertible preferred stock issuance costs	(19)		(19)
Exercise of stock options (in shares)		1,122
Exercise of stock options	3		3
Stock-based compensation expense	1,074		1,074
Unrealized gain (loss) on available-for-sale debt securities	59			59
Net Income (Loss)	(21,499)				(21,499)
Ending balance (in shares) at Jun. 30, 2023						11,250,000	16,285,156	25,065,538	17,905,288	29,285,356
Ending balance at Jun. 30, 2023						$ 8,643	$ 12,611	$ 28,860	$ 42,100	$ 79,769
Ending balance (in shares) at Jun. 30, 2023		3,029,258
Ending balance at Jun. 30, 2023	(120,605)	$ 3	22,614	(233)	(142,989)
Proceeds from initial public offering, net of issuance costs (in shares)		7,318,275
Proceeds from initial public offering, net of issuance costs	75,963	$ 7	75,956
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering (in shares)						(11,250,000)	(16,285,156)	(25,065,538)	(17,905,288)	(29,285,356)
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering						$ (8,643)	$ (12,611)	$ (28,860)	$ (42,100)	$ (79,769)
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering (in shares)		12,493,879
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering	171,983	$ 13	171,970
Issuance of common stock upon Myst milestone achievement (in shares)		249,992
Issuance of common stock upon Myst milestone achievement	2,812		2,812
Exercise of stock options (in shares)		1,671
Exercise of stock options	9		9
Stock-based compensation expense	1,064		1,064
Unrealized gain (loss) on available-for-sale debt securities	(8)			(8)
Net Income (Loss)	(17,319)				(17,319)
Ending balance (in shares) at Sep. 30, 2023		23,093,075
Ending balance at Sep. 30, 2023	$ 113,899	$ 23	274,425	(241)	(160,308)
Beginning balance (in shares) at Dec. 31, 2023	23,099,335	23,099,335
Beginning balance at Dec. 31, 2023	$ 98,667	$ 23	275,521	(119)	(176,758)
Exercise of stock options (in shares)		29,119
Exercise of stock options	44		44
Stock-based compensation expense	1,046		1,046
Unrealized gain (loss) on available-for-sale debt securities	(117)			(117)
Net Income (Loss)	(19,629)				(19,629)
Ending balance (in shares) at Mar. 31, 2024		23,128,454
Ending balance at Mar. 31, 2024	$ 80,011	$ 23	276,611	(236)	(196,387)
Beginning balance (in shares) at Dec. 31, 2023	23,099,335	23,099,335
Beginning balance at Dec. 31, 2023	$ 98,667	$ 23	275,521	(119)	(176,758)
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering (in shares)		12,493,879
Exercise of stock options (in shares)	29,119
Unrealized gain (loss) on available-for-sale debt securities	$ (77)
Net Income (Loss)	$ (57,965)
Ending balance (in shares) at Sep. 30, 2024	23,128,454	23,128,454
Ending balance at Sep. 30, 2024	$ 43,641	$ 23	278,537	(196)	(234,723)
Beginning balance (in shares) at Mar. 31, 2024		23,128,454
Beginning balance at Mar. 31, 2024	80,011	$ 23	276,611	(236)	(196,387)
Stock-based compensation expense	1,019		1,019
Unrealized gain (loss) on available-for-sale debt securities	10			10
Net Income (Loss)	(21,304)				(21,304)
Ending balance (in shares) at Jun. 30, 2024		23,128,454
Ending balance at Jun. 30, 2024	59,736	$ 23	277,630	(226)	(217,691)
Stock-based compensation expense	907		907
Unrealized gain (loss) on available-for-sale debt securities	30			30
Net Income (Loss)	$ (17,032)				(17,032)
Ending balance (in shares) at Sep. 30, 2024	23,128,454	23,128,454
Ending balance at Sep. 30, 2024	$ 43,641	$ 23	$ 278,537	$ (196)	$ (234,723)

Summary of Significant Accounting Policies	9 Months Ended
Summary of Significant Accounting Policies	Sep. 30, 2024
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation of Unaudited Condensed Consolidated Financial Information The accompanying unaudited condensed consolidated financial statements of the Company have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information and pursuant to the rules and regulations of the SEC. Accordingly, they do not include all the information and footnotes required by GAAP for complete financial statements. However, such interim financial statements reflect all adjustments (consisting solely of normal recurring adjustments), which are, in the opinion of management, necessary for the fair presentation of the Company’s financial position and results of operations. Results shown for interim periods are not necessarily indicative of the results that may be expected for the year ended December 31, 2024 or for any other period. The condensed consolidated balance sheet as of December 31, 2023 was derived from the audited consolidated financial statements. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements, included in the Company’s Annual Report on Form 10-K filed with the SEC on March 22, 2024. Certain prior period amounts reported in the Company’s unaudited condensed consolidated financial statements and accompanying notes have been reclassified to conform to the current period presentation. Any reference in these notes to applicable guidance is meant to refer to the authoritative accounting principles generally accepted in the United States as found in the Accounting Standard Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”). Principles of Consolidation The accompanying unaudited condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. Significant Accounting Policies The significant accounting policies used in preparation of these unaudited condensed consolidated financial statements are consistent with those discussed in Note 2 to the audited consolidated financial statements included in the Company’s Annual Report filed on Form 10-K filed with the SEC on March 22, 2024. Use of Estimates The preparation of these unaudited condensed consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the amounts reported in the unaudited condensed consolidated financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to accrued expenses, contingent liabilities, impairment of long-lived assets, revenue recognition, the valuation of equity-based compensation, common stock, restricted common stock, and income taxes. The Company bases its estimates on various assumptions that the Company believes to be reasonable under the circumstances. Actual results could differ from those estimates. Restricted Cash and Investments Restricted cash consists of certificate of deposit accounts that are pledged as collateral for the Company’s San Diego facility lease. Restricted cash was approximately $0.1 million as of September 30, 2024 and December 31, 2023, respectively. The Company invests its excess cash in investment grade, short-term, fixed income securities and recognizes purchased securities on the settlement date. All investments have been classified as “available-for-sale” in the unaudited condensed consolidated balance sheets and are carried at estimated fair value based upon quoted market prices or pricing models for similar securities. Management determines the appropriate classification of its investments at the time of purchase and re-evaluates such designation as of each balance sheet date. The Company assesses its available-for-sale securities under the available-for-sale security impairment model in ASC Topic 326, Financial Instruments - Credit Losses ("ASC 326") as of each reporting date in order to determine if a portion of any decline in fair value below carrying value is the result of a credit loss. The Company records credit losses in the unaudited condensed consolidated statements of operations and comprehensive loss as credit loss expense, which is limited to the difference between the fair value and the amortized cost of the security. To date, the Company has not recorded any credit losses on its available-for-sale securities. Declines in fair value below carrying value attributable to non-credit related factors are recorded as accumulated other comprehensive loss, which is a separate component of stockholders’ equity. Realized gains and losses are reported in other income (expense), net. Interest on short-term investments is included in other income (expense), net. The Company’s investments are classified as current assets which reflects management’s intention to use the proceeds from sales of these securities to fund its operations, as necessary. Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash and cash equivalents, investments and restricted cash. The Company’s investment policy restricts cash investments to high credit quality, investment grade investments. The Company’s investment policy provides guidelines and limits regarding investment type, concentration, credit quality, and maturity aimed at maintaining sufficient liquidity to satisfy operating and working capital requirements along with strategic initiatives, preserving capital, and minimizing risk of capital loss while generating returns on its investments. The Company is exposed to credit risk in the event of default by the issuer or the institutions holding the cash and cash equivalents to the extent of the amounts recorded on the balance sheets. The Company has no off-balance sheet risk, such as foreign exchange contracts, option contracts or other foreign-hedging arrangements. Fair Value Measurements The Company applies fair value accounting for all financial assets and liabilities and non-financial assets and liabilities that are recognized or disclosed at fair value in the unaudited condensed consolidated financial statements on a recurring basis. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The fair value hierarchy requires that an entity maximize the use of observable inputs when estimating fair value. The fair value hierarchy includes the following three-level classification which is based on the market observability of the inputs used for estimating the fair value of the assets or liabilities being measured: Level 1 – Quoted market prices in active markets for identical assets or liabilities. Level 2 – Observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 – Inputs that are generally unobservable and typically reflect management’s estimate of assumptions that a market participant would use in pricing the asset or liability. Fair value accounting is applied for all financial assets and liabilities and non-financial assets and liabilities that are recognized at fair value in the unaudited condensed consolidated financial statements on a recurring basis (at least annually). To the extent the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair values requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized as Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. Stock-Based Compensation The Company accounts for stock-based compensation expense related to stock options and restricted stock units, ("RSUs"), by estimating the fair value on the date of grant. The fair value of RSUs granted to employees is the closing price of the Company’s common stock on the date of grant. The Company estimates the fair value of stock options granted to employees and non-employees using the Black-Scholes option pricing model. The Company recognizes stock-based compensation expense, over the requisite service period, based on the vesting provisions of the individual grants. Generally, the Company issues stock-based awards with only service-based vesting conditions and records the expense for these awards using the straight-line method. The Company accounts for forfeitures when they occur. The Black-Scholes option pricing model requires inputs based on certain subjective assumptions, including (a) the expected stock price volatility, (b) the expected term of the award, (c) the risk-free interest rate and (d) expected dividend yields. Due to the lack of a public market for the Company’s common stock until July 21, 2023, and lack of company- specific historical and implied volatility data, the Company has based its computation of expected volatility on the average historical volatility of a representative group of public companies with similar characteristics to the Company, including stage of product development and life science industry focus. The historical volatility is calculated based on a period of time commensurate with the expected term. The Company uses the simplified method as prescribed by the U.S. Securities and Exchange Commission Staff Accounting Bulletin No. 107, Share-Based Payment, to calculate the expected term for options granted to employees as it does not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term. The expected term is applied to the stock option grant group as a whole, as the Company does not expect substantially different exercise or post-vesting termination behavior among its employee population. The risk-free interest rate is based on a treasury instrument whose term is consistent with the expected term of the stock options. The expected dividend yield is assumed to be zero as the Company has never paid dividends and has no current plans to pay any dividends on its common stock. Determination of Fair Value of Common Stock After the Company's IPO in July 2023, the fair value of common stock is determined using the closing price of the Company's common stock on the Nasdaq Global Market. Prior to the IPO, there were significant judgments and estimates inherent in the determination of the fair value of the Company’s common stock. These estimates and assumptions include a number of objective and subjective factors, including, among other things, external market conditions, the prices at which the Company sold shares of its convertible preferred stock, the superior rights and preferences of securities senior to its common stock at the time of, and the likelihood of, achieving a liquidity event, such as an initial public offering or sale of the Company. The approach to estimating the fair market value of common stock is consistent with the methods outlined in the American Institute of Certified Public Accountants’ Accounting and Valuation Guide, Valuation of Privately-Held Company Equity Securities Issued as Compensation (the “Practice Aid”). In valuing the Company’s common stock prior to the IPO, the equity value of the business was determined using the backsolve method, a form of the subject company transaction method, wherein the equity value for a privately held company is derived from a recent transaction in the company’s own securities. The value is then allocated using the hybrid method allocation methodology. For grants made subsequent to September 30, 2018 but prior to the IPO, the Company used a hybrid method, which is a hybrid between the OPM and the probability-weighted expected return method (“PWERM”). The hybrid method is a combination of the PWERM and OPM. The OPM allocates the overall Company value to the various share classes based on differences in liquidation preferences, participation rights, dividend policy and conversion rights, using a series of call options. The call right is valued using a Black-Scholes option pricing model. The PWERM employs additional information not used in the OPM, including various market approach calculations depending upon the likelihood of various discrete future liquidity scenarios, such as an initial public offering or sale of the Company, as well as the probability of remaining a private company. In a hybrid method, various exit scenarios are analyzed. A discount for lack of marketability of the Company’s common stock was then applied to arrive at an indication of value for the common stock. Contingent Consideration Consideration paid related to the Myst Merger Agreement (see Note 7 - Asset Acquisition for additional information) may include potential future payments that are contingent upon the Company achieving certain milestones in the future. Contingent consideration liabilities are measured at their estimated fair value as of the date of the unaudited condensed consolidated balance sheets using a probability-based income approach based on the monetary value of the milestone payment discounted for the likelihood of achieving the milestone and a present value factor based on the timing of when the milestone is expected to be achieved. Contingent consideration liabilities expected to be settled within 12 months after the balance sheet date are presented in current liabilities, with the non-current portion recorded under other liabilities, non-current in the unaudited condensed consolidated balance sheets. Changes in the fair value of the contingent consideration are recorded as research and development expenses in the unaudited condensed consolidated statement of operations and comprehensive loss. Recently Adopted Accounting Pronouncements In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging Contracts in Entity’s Own Equity (Subtopic 815-40) (“ASU 2020-06”), which reduces the number of accounting models for convertible debt instruments and convertible preferred stock as well as amends the derivatives scope exception for contracts in an entity’s own equity. ASU 2020-06 is effective for the Company on January 1, 2024. The adoption did not have a material impact on the unaudited condensed consolidated financial statements. Recently Issued Accounting Pronouncements In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280)—Improvements to Reportable Segment Disclosures (“ASU 2023-07”). ASU 2023-07 requires that an entity disclose significant segment expenses impacting profit and loss that are regularly provided to the chief operating decision maker. The update is required to be applied retrospectively to prior periods presented, based on the significant segment expense categories identified and disclosed in the period of adoption. The amendments in ASU 2023-07 are required to be adopted for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. The Company is currently evaluating the potential impact that this standard may have on its unaudited condensed consolidated financial statements and related disclosures. In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740)—Improvements to Income Tax Disclosures (“ASU 2023-09”). ASU 2023-09 requires that an entity disclose specific categories in the effective tax rate reconciliation as well as provide additional information for reconciling items that meet a quantitative threshold. Further, ASU 2023-09 requires certain disclosures of state versus federal income tax expense and taxes paid. The amendments in ASU 2023-09 are required to be adopted for fiscal years beginning after December 15, 2024. Early adoption is permitted for annual financial statements that have not yet been issued. The amendments should be applied on a prospective basis although retrospective application is permitted. The Company is currently evaluating the potential impact that this standard may have on its unaudited condensed consolidated financial statements and related disclosures.

Redeemable Convertible Preferred Stock and Stockholders' Equity

9 Months Ended

Sep. 30, 2024

Stockholders' Equity Note [Abstract]

Redeemable Convertible Preferred Stock and Stockholders' Equity

9. Redeemable Convertible Preferred Stock and Stockholders’ Equity

Redeemable Convertible Preferred Stock

From October 2015 to October 2016, the Company issued a total of 11,250,000 shares of series A preferred stock (the “Series A Preferred Stock”) at CDN$1.00 per share (equivalent to $0.74 per share, based on a conversion ratio of 1.344 Canadian dollars to one U.S. dollar) for total net proceeds of CDN$ 10.9 million (equivalent to $8.1 million based on a conversion ratio of 1.344 Canadian dollars to one U.S. dollar).

In October 2016, the Company issued a total of 16,285,156 shares of series B-1 preferred stock (the “Series B-1 Preferred Stock”) at $0.77 per share for total net proceeds of $12.3 million. In November 2018, the Company issued 25,065,538 shares of series B-2 preferred stock (the “Series B-2 Preferred Stock”, and together with the Series B-1 Preferred Stock, the “Series B Preferred Stock”) at $1.15 per share for total net proceeds of $28.9 million.

The Company issued a total of 17,905,288 shares of series C preferred stock (the “Series C Preferred Stock”) at $2.35 per share in January 2019 for net proceeds of $41.8 million.

The Company issued a total of 29,285,356 shares of series D preferred stock (the “Series D Preferred Stock”) at $2.73 per share in June 2021 for net proceeds of $79.8 million.

In connection with the Company's IPO, all outstanding shares of the Company's redeemable convertible preferred stock automatically converted into 12,493,879 shares of common stock. Subsequent to the closing of the IPO, there were no shares of redeemable convertible preferred stock outstanding.

Common Stock

In connection with the closing of the IPO, the Company filed its Amended and Restated Certificate of Incorporation which provides that the authorized common stock of the Company is 490,000,000 shares of common stock with a par value of $0.001 per share.

Shares of common stock reserved for future issuance consisted of the following:


	September 30,		December 31,
	2024		2023
Common stock options outstanding		3,137,504		3,374,282
Unvested RSUs		104,093		102,945
Shares available for issuance under the ESPP		453,280		222,287
Shares available for issuance under the Plans		3,111,908		1,755,404
		6,806,785		5,454,918

- Definition

The entire disclosure for equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Paragraph 13
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Fair Value of Financial Assets and Liabilities

9 Months Ended

Sep. 30, 2024

Fair Value Disclosures [Abstract]

Fair Value of Financial Assets and Liabilities

3. Fair Value of Financial Assets and Liabilities

As of September 30, 2024 and December 31, 2023, the Company’s highly liquid money market funds included within cash equivalents, restricted cash and U.S. treasury securities are valued using Level 1 inputs. The Company classifies its federal agency securities as Level 2. There were no transfers in or out of Level 1 and Level 2 during the periods presented. U.S. treasury securities are bonds issued by the U.S. government and are fully backed by the U.S. government. Given the frequency at which U.S. treasury securities trade and the accessibility of observable, quoted prices for such assets in active markets, they are recognized as Level 1 assets. Federal agency securities are bonds and notes issued by government-sponsored enterprises, including Fannie Mae, Freddie Mac and the Federal Home Loan Bank. Since Federal agency securities typically do not trade as frequently as U.S. government agency securities and no exchange exists to price such investments, they are recognized as Level 2 assets.

The Company had $0.9 million in contingent consideration liabilities as of September 30, 2024 and December 31, 2023, respectively, related to the Myst Merger Agreement. The contingent consideration balance is comprised of one potential milestone payment and is measured at fair value (see Note 7—Asset Acquisition for additional information). The fair value of the contingent consideration is estimated based on the monetary value of the milestone discounted for the likelihood of achieving the milestone and a present value factor based on the timing of when the milestone is expected to be achieved. The value for the contingent consideration balance is based on significant inputs not observable in the market which represents a Level 3 measurement within the fair value hierarchy. There were no transfers in or out of Level 3 during the periods presented.

The following tables represent a summary of the financial assets and liabilities that are measured on a recurring basis at fair value (in thousands):


	September 30, 2024
	Level 1		Level 2		Level 3		Fair Value
Financial assets:
Money market funds	$	16,104	$	—	$	—	$	16,104
Restricted cash(1)		116		—		—		116
U.S. government securities(2)		21,151		—		—		21,151
Total financial assets	$	37,371	$	—	$	—	$	37,371
Financial liabilities:
Contingent consideration(3)	$	—	$	—	$	866	$	866
Total financial liabilities	$	—	$	—	$	866	$	866


	December 31, 2023
	Level 1		Level 2		Level 3		Fair Value
Financial assets:
Money market funds	$	15,635	$	—	$	—	$	15,635
Restricted cash(1)		116		—		—		116
U.S. government securities(2)		76,979		—		—		76,979
Total financial assets	$	92,730	$	—	$	—	$	92,730
Financial liabilities:
Contingent consideration(3)	$	—	$	—	$	916	$	916
Total financial liabilities	$	—	$	—	$	916	$	916

(1)

Restricted cash serves as deposits for the Company’s San Diego office lease.

(2)

Included in short-term investments on the unaudited condensed consolidated balance sheets and are classified as available-for sale debt securities.

(3)

Contingent consideration related to the Myst Merger Agreement.


	Fair Value as of
Contingent Consideration Liability	September 30, 2024		Valuation Technique	Unobservable Input	Amount
	(in thousands)
Milestone payment for first registrational study (see Note 7 - Asset Acquisition for additional information)	$	866	Discounted cash flow	Likelihood of occurrence	10%
				Discount rate	25%
				Expected term (in years)	3.8

	Fair Value as of
Contingent Consideration Liability	December 31, 2023		Valuation Technique	Unobservable Input	Amount
	(in thousands)
Milestone payment for first registrational study (see Note 7 - Asset Acquisition for additional information)	$	916	Discounted cash flow	Likelihood of occurrence	10%
				Discount rate	25%
				Expected term (in years)	3.5

The following table reflects the activity for the Company’s contingent consideration, measured at fair value using Level 3 inputs (in thousands):


Contingent consideration at December 31, 2023	$	916
Changes in the fair value of contingent consideration		(49	)
Contingent consideration at September 30, 2024	$	866

The following tables show the Company’s cash, cash equivalents and available-for-sale securities by significant investment category (in thousands):


	September 30, 2024
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Level 1: Money market funds	$	16,104	$	—	$	—	$	16,104
Restricted cash		116		—		—		116
U.S. government securities		21,145		—		6		21,151
Total financial assets	$	37,365	$	—	$	6	$	37,371
Classified as:
Cash and cash equivalents							$	16,104
Restricted cash								116
Short-term investments								21,151
							$	37,371


	December 31, 2023
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Level 1: Money market funds	$	15,635	$	—	$	—	$	15,635
Restricted cash		116		—		—		116
U.S. government securities		76,875		104		—		76,979
Total financial assets	$	92,626	$	104	$	—	$	92,730
Classified as:
Cash and cash equivalents							$	15,635
Restricted cash								116
Short-term investments								76,979
							$	92,730

As of September 30, 2024, none of our 7 available-for-sale debt securities were in a gross unrealized loss position with an aggregate fair value of $21.2 million. As of December 31, 2023, none of our 28 available-for-sale debt securities were in a gross unrealized loss position. While short-term investments are available-for-sale, it is not more likely than not that the Company will be required to sell the investments before recovery of their amortized cost bases, which may be maturity. All short-term investments currently held have maturities of less than one year.

The Company reviews short-term investments for impairment during each reporting period. Credit losses are recognized up to the amount equal to the difference between the fair value and the amortized cost basis and recorded as an allowance for credit losses in the unaudited condensed consolidated balance sheets with a corresponding adjustment to earnings. Unrealized losses that are not related to credit losses are recognized in accumulated other comprehensive loss. Unrealized losses were not significant for the investments held in the Company’s portfolio as of September 30, 2024 and Company considered the decline in market value for these securities to be primarily attributable to economic and market conditions rather than credit-related factors. There were no unrealized losses in the Company's investment portfolio at December 31, 2023. The Company considered the risk-profile of the counterparties under ASC 326, noting that any credit risk associated with such entities is either zero or near zero. There were no impairment losses or expected credit losses related to its short-term investments during the three and nine months ended September 30, 2024 and 2023.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References

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+ Details