| Summary of Significant Accounting Policies | Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements reflect the operations of the Company and have been prepared in conformity with generally accepted accounting principles in the United States of America (GAAP). Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the ASC and Accounting Standards Update (ASU) of the Financial Accounting Standards Board (FASB). Principles of Consolidation The accompanying consolidated financial statements include those of the Company and its wholly-owned subsidiary. All intercompany balances and transactions have been eliminated in consolidation. Use of Estimates The preparation of the Company’s consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenue and expenses, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, estimates related to revenue recognition, accrual and prepayment of research and development expenses, the valuation of stock-based compensation and income taxes. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates, as there are changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results may differ from those estimates or assumptions. Segment Information The Company manages its operations as a single segment. The Company’s chief operating decision maker, its Chief Executive Officer, manages the Company’s operations on a consolidated basis for the purposes of assessing performance and making operating decisions. Revenue Recognition To date, all revenue has been generated from the Company's Strategic Collaboration and License Agreement with Vertex, which closed in February 2023 and was amended in October 2023 (Vertex Agreement), and falls within the scope of ASC Topic 606, "Revenue from Contracts with Customers" (ASC 606), under which the Company licensed rights to VX-670 and performs research and development services. The terms of this arrangement includes a non-refundable upfront payment, reimbursement for research and development costs; development, regulatory, and commercial milestone payments; and royalties on net sales of licensed products. Under Topic 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of Topic 606, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price, including variable consideration, if any; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that the entity will collect the consideration to which it is entitled in exchange for the goods or services it transfers to the customer. For contracts within the scope of ASC 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations. Arrangements that include rights to additional goods or services that are exercisable at a customer’s discretion are generally considered options. The Company assesses if these options provide a material right to the customer and if so, they are considered separate performance obligations. The identification of material rights requires judgments related to the determination of the value of the underlying license relative to the option exercise price, including assumptions about technical feasibility and the probability of developing a candidate that would be subject to the option rights. The exercise of a material right is accounted for as a contract modification for accounting purposes. The Company assesses whether each promised good or service is distinct for the purpose of identifying the performance obligations in the contract. This assessment involves subjective determinations and requires management to make judgments about the individual promised goods or services and whether such promised goods or services are separable from the other aspects of the contractual relationship. Promised goods and services are considered distinct provided that: (i) the customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer (that is, the good or service is capable of being distinct) and (ii) the entity’s promise to transfer the good or service to the customer is separately identifiable from other promises in the contract (that is, the promise to transfer the good or service is distinct within the context of the contract). In assessing whether a promised good or service is distinct, the Company considers factors such as the research, manufacturing and commercialization capabilities of the collaboration partner and the availability of the associated expertise in the general marketplace. The Company also considers the intended benefit of the contract in assessing whether a promised good or service is separately identifiable from other promises in the contract. If a promised good or service is not distinct, an entity is required to combine that good or service with other promised goods or services until it identifies a bundle of goods or services that is distinct. The Company estimates the transaction price based on the amount expected to be received for transferring the promised goods or services in the contract. The consideration may include fixed consideration or variable consideration. For contracts within the scope of ASC 606 that contain elements within the scope of a different ASC Topic, the Company excludes the fair value such elements from the transaction price. If the consideration promised in a contract includes a variable amount, the Company estimates the amount of consideration to which it will be entitled in exchange for transferring the promised goods or services to a customer. The Company determines the amount of variable consideration by using the expected value method or the most likely amount method. The Company includes the unconstrained amount of estimated variable consideration in the transaction price. The amount included in the transaction price is constrained to the amount for which it is probable that a significant reversal of cumulative revenue recognized will not occur. At the end of each subsequent reporting period, the Company re-evaluates the estimated variable consideration included in the transaction price and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis in the period of adjustment as a change in estimate. If an arrangement includes development or regulatory milestone payments, the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price in the period in which the Company deems the milestone to be probable. Milestone payments that are not within the Company’s control or a customer's control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received. The transaction price is allocated to the identified performance obligations in proportion to their standalone selling prices (SSP) on a relative SSP basis. SSP is determined at contract inception and is not updated to reflect changes between contract inception and when the performance obligations are satisfied. Determining the SSP for performance obligations may require significant judgment. In developing the SSP for a performance obligation, the Company considers applicable market conditions and relevant entity-specific factors, including factors that were contemplated in negotiating the agreement with the customer and estimated costs. The Company validates the SSP for performance obligations by evaluating whether changes in the key assumptions used to determine the SSP will have a significant effect on the allocation of arrangement consideration between multiple performance obligations. For arrangements with licenses of intellectual property that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes royalty revenue and sales-based milestones at the later of (i) when the related sales occur, or (ii) when the performance obligation to which the royalty has been allocated has been satisfied. Up-front and milestone payments are recorded as deferred revenue upon receipt or when due until the Company performs its obligations under these arrangements. Amounts are recorded as a collaboration receivable when the Company's right to consideration is unconditional. To date, the Company has not recorded any credit losses on its collaboration receivables. The Company then recognizes the revenue allocated to each performance when (or as) each performance obligation is satisfied, either at a point in time or over time. Any over time recognition is based on the use of an output or input method. Concentrations of Credit Risk and Off-Balance Sheet Risk Financial instruments that potentially subject the Company to significant concentration of credit risk consist primarily of cash, cash equivalents, restricted cash and marketable securities. Periodically, the Company may maintain deposits in financial institutions in excess of government insured limits. Management believes that the Company is not exposed to significant credit risk as the Company’s deposits are held at financial institutions that management believes to be of high credit quality, and the Company has not experienced any losses on these deposits. The Company’s marketable securities primarily consist of corporate bonds and U.S. government agency securities and treasuries, and potentially subject the Company to concentrations of credit risk. Our cash management and investment policy limits investment instruments to investment-grade securities with the objective to preserve capital and to maintain liquidity until the funds can be used in business operations The Company has no off-balance sheet risk, such as foreign exchange contracts, option contracts, or other foreign-hedging arrangements. Cash, Cash Equivalents, and Restricted Cash The Company considers all highly liquid investments with a remaining maturity of 90 days or less at the date of purchase to be cash equivalents. At December 31, 2023 and 2022 cash and cash equivalents include standard checking accounts and money market account funds that invest primarily in U.S. government-backed securities and treasuries. As of December 31, 2023 and 2022, restricted cash represents collateral provided for a letter of credit issued as a security deposit in connection with the Company’s lease of its corporate facilities located at One Design Center Place, Boston, Massachusetts. A reconciliation of the cash, cash equivalents, and restricted cash reported within the balance sheet that sum to the total of the same amounts shown in the statement of cash flows is as follows (in thousands): December 31, December 31, Cash and cash equivalents $ 67,602 $ 45,157 Restricted cash 3,950 3,950 Total cash, cash equivalents and restricted cash $ 71,552 $ 49,107 Marketable Securities Investments in marketable securities are classified as available-for-sale. Available-for-sale securities are measured and reported at fair value using quoted prices in active markets for similar securities. Unrealized gains and losses on available-for-sale securities are reported as a separate component of stockholders’ equity. Premiums or discounts from par value are amortized or accreted to investment income and/or expense over the life of the underlying investment. All of the Company’s marketable securities are available to the Company for use in current operations. As a result, the Company classified all of these securities as current assets even though the stated maturity of some individual securities may be one year or more beyond the balance sheet date. Realized gains and losses are determined using the specific identification method and are included in interest and other income in our consolidated statement of operations. The Company assesses impairment for its marketable securities under the available-for-sale debt security impairment model in ASC 326 as of each reporting date. Based on the model, we 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 consolidated statements of operations and comprehensive loss as credit loss expense within interest and other income, 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 debt securities. Accrued interest receivable related to the Company's available-for-sale debt securities is presented within prepaid expenses and other current assets on the Company's consolidated balance sheets. The Company has elected the practical expedient available to exclude accrued interest receivable from both the fair value and the amortized cost basis of available-for-sale debt securities for the purposes of identifying and measuring any impairment. The Company writes off accrued interest receivable once it has determined that the asset is not realizable. Any write offs of accrued interest receivable are recorded by reversing interest income, recognizing credit loss expense, or a combination of both. To date, the Company has not written off any accrued interest receivables associated with its marketable securities. Fair Value Measurements ASC Topic 820, Fair Value Measurement (ASC 820), establishes a fair value hierarchy for instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and the Company’s own assumptions (unobservable inputs). Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the assets or liability and are developed based on the best information available under the circumstances. ASC 820 identifies fair value as the price that would be received to sell an asset or paid to transfer a liability, in an orderly transaction between market participants at the measurement date. As a basis for considering market participant assumptions in fair value measurements, ASC 820 establishes a three-tiered value hierarchy that distinguishes between the following: • Level 1—Quoted prices in active markets for identical assets or liabilities. • Level 2—Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. • Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. 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. The Company evaluates transfers between levels at the end of each reporting period. There were no transfers of financial instruments between levels during the years ended December 31, 2023 and 2022. The carrying amounts of accounts payable and accrued expenses approximate their fair values due to their short-term nature. Property and Equipment Property and equipment are stated at cost less accumulated depreciation. Depreciation expense is recognized using the straight line method over the estimated useful life of each asset as follows: Estimated Useful Life Laboratory equipment 5 years Furniture and fixtures 5 years Computer equipment 3 years Leasehold improvements Lesser of estimated useful life or remaining lease term Costs for capital assets not yet placed into service are capitalized as construction-in-progress and depreciated once placed into service. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is included in other income (expense), net. Expenditures for repairs and maintenance that do not improve or extend the life of the respective assets are expensed in operations as incurred. Leases At the inception of a lease arrangement, the Company determines whether the arrangement is or contains a lease based on the u nique facts and circumstances present in the arrangement. Leases with a term greater than one year are recognized on the balance sheet as right-of-use assets and current and non-current lease liabilities, as applicable. The Company has elected not to recognize leases with an original term of one year or less on the balance sheet. Operating lease liabilities and their corresponding right-of-use assets are initially recorded based on the present value of lease payments over the expected remaining lease term. Certain adjustments to the right-of-use asset may be required for items such as incentives received. The interest rate implicit in lease contracts is typically not readily determinable. As a result, the Company utilizes its incremental borrowing rate to discount lease payments, which reflects the fixed rate at which the Company could borrow on a collateralized basis the amount of the lease payments in the same currency, for a similar term, in a similar economic environment. To estimate its incremental borrowing rate, a credit rating applicable to the Company is estimated using a synthetic credit rating analysis since the Company does not currently have a rating agency-based credit rating. Prospectively, the Company adjusts the right-of-use assets for straight-line rent expense or any incentives received and remeasures the lease liability at the net present value using the same incremental borrowing rate that was in effect as of the lease commencement or transition date. Lease expense for lease payments is recognized on a straight-line basis over the assigned lease term. Assumptions made by the Company at the commencement date are re-evaluated upon occurrence of certain events, including a lease modification. Changes to the terms and conditions of a lease that result in a change in the scope of or the consideration for the lease result in a lease modification. A lease modification that grants the lessee an additional right of use not included in the original lease and when lease payments increase commensurate with the standalone price for the additional right of use is treated as a separate contract. When a lease modification results in a separate contract, it is accounted for in the same manner as a new lease. For any lease modifications that aren't accounted for as separate contracts, the Company remeasures its right-of-use assets and lease liabilities as of the modification date. The Company assesses its right-of-use assets for impairment in a manner consistent with its assessment for long-lived assets held and used in operations. Impairment of Long-Lived Assets The Company evaluates its long-lived assets, which consist primarily of property and equipment, for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the future undiscounted net cash flows expected to be generated by the asset. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the asset exceeds the fair value of the asset. There were no impairment losses recognized during the years ended December 31, 2023 and 2022. Deferred Offering Costs The Company capitalizes incremental legal, professional accounting and other third-party fees that are incurred in the course of preparing for a financing as other non-current assets until the offering is consummated. At the time of the completion of the offering, the costs are reclassified as a reduction of the proceeds of the financing as part of additional paid-in-capital. Should the offering be terminated, deferred offering costs are charged to operations during the period in which the offering is terminated. Contingencies The Company records liabilities for legal and other contingencies when information available to the Company indicates that it is probable that a liability has been incurred and the amount of loss can be reasonably estimated. Legal costs in connection with legal and other contingencies are expensed as costs are incurred. No liabilities for legal and other contingencies were accrued as of December 31, 2023 and 2022. Indemnification Agreements In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, contract research organizations (CROs), business partners and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its board of directors and its executive officers that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. The Company has not incurred any material costs as a result of such indemnifications and is not currently aware of any indemnification claims. Research and Development Expenses Research and development costs are charged to expense as incurred. Research and development costs consist of direct and allocated costs incurred in performing research and development activities, including salaries and bonuses, stock-based compensation, employee benefits, facilities costs, third-party license fees related to technology with no alternative future use, laboratory supplies, depreciation, manufacturing expenses, preclinical expenses, clinical expenses, consulting and other contracted services. Non-refundable prepayments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized. Such amounts are recognized as an expense as the goods are delivered or the related services are performed or until it is no longer expected that the goods will be delivered or the services rendered. The Company has entered into various research and development related contracts with third parties. These agreements are cancellable with prior written notice, and related fees are recorded as research and development expenses as incurred. Payments for these agreements are based on the terms of the individual contracts, which may differ from the pattern of costs incurred, and payments made in advance of performance are reflected in the accompanying consolidated balance sheets as prepaid and other assets or accrued liabilities. When evaluating the adequacy of the accrued liabilities and prepaid expenses, the Company analyzes progress of the studies, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates are made in determining the accrued and prepaid balances at the end of any reporting period. Actual results could differ from the Company’s estimates. Patent Costs All patent-related costs incurred in connection with filing and prosecuting patent applications are expensed as incurred due to the uncertainty about the recovery of the expenditure. Amounts incurred are classified as general and administrative expenses. Stock-Based Compensation The Company’s stock-based compensation program allows for grants of stock options and restricted stock units. Grants are awarded to employees and non-employees, including the Company’s board of directors. The Company accounts for its stock-based compensation in accordance with ASC Topic 718, Compensation-Stock Compensation (ASC 718). ASC 718 requires all stock-based payments to employees, non-employees and directors, to be recognized as expense in the consolidated statements of operations based on their grant date fair values. The Company estimates the fair value of options granted using the Black-Scholes option-pricing model (Black-Scholes) for stock option grants to both employees and non-employees. The fair value of the Company’s common stock is used to determine the fair value of restricted stock units. The Company’s stock-based compensation awards are subject to service-based vesting conditions. Compensation expense related to awards to employees, directors and non-employees with service-based vesting conditions is recognized on a straight-line basis based on the grant date fair value over the associated service period of the award, which is generally the vesting term. Black-Scholes requires inputs based on certain subjective assumptions, including (i) the expected stock price volatility, (ii) the expected term of the award, (iii) the risk-free interest rate and (iv) expected dividends. The Company determines the expected volatility using the historical volatility of a peer group of comparable publicly traded companies with comparable characteristics and with historical share price information that approximates the expected term of the stock-based awards. The Company uses the simplified method as prescribed by the SEC Staff Accounting Bulletin No. 107, Share-Based Payment, to calculate the expected term for options granted to employees and non-employees whereby, the expected term equals the arithmetic average of the vesting term and the original contractual term of the options due to its lack of sufficient historical data. The risk-free interest rate is based on U.S. Treasury securities with a maturity date commensurate with the expected term of the associated award. 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. The Company recognizes forfeitures as they occur. Prior to the Company’s IPO, there was no public market for its common stock, and consequently, the estimated fair value of its common stock was determined by the board of directors as of the date of each option grant, with input from management, considering third-party valuations of its common stock as well as its board of directors’ assessment of additional objective and subjective factors that it believed were relevant and which may have changed from the date of the most recent third-party valuation through the date of the grant. These third-party valuations were performed in accordance with the guidance outlined in the American Institute of Certified Public Accountants’ Accounting and Valuation Guide, Valuation of Privately-Held-Company Equity Securities Issued as Compensation (Practice Aid). The Practice Aid identifies various available methods for allocating the enterprise value across classes of series of capital stock in determining the fair value of the Company’s common stock at each valuation date. Subsequent to the Company’s IPO, the fair value of the common stock underlying the stock-based awards is the closing price of the Company’s common stock on the date of grant. The Company classifies stock-based compensation expense in its consolidated statements of operations in the same manner in which the award recipient’s payroll costs are classified or in which the award recipient’s service payments are classified. Income Taxes Income taxes are recorded in accordance with FASB ASC Topic 740, Income Taxes (ASC 740), which provides for deferred taxes using an asset and liability approach. The Company accounts for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the consolidated financial statements or in the Company’s tax returns. Deferred tax assets and liabilities are determined on the basis of the differences between the consolidated financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent it believes, based upon the weight of available evidence, that it is more likely than not that all or a portion of the deferred tax assets will not be realized, a valuation allowance is established through a charge to income tax expense. Potential for recovery of deferred tax assets is evaluated by estimating the future taxable profits expected and considering prudent and feasible tax planning strategies. Net Loss per Share The Company follows the two-class method when computing net loss per share, as the Company has issued shares that meet the definition of participating securities. The two-class method determines net loss per share for each class of common and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income available to common stockholders for the period to be allocated between common and participating securities based upon their respective rights to receive dividends as if all income for the period had been distributed. During periods of loss, there is no allocation required under the two-class method since the participating securities do not have a contractual obligation to fund the losses of the Company. Basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted average number of common shares outstanding for the period. Diluted net loss attributable to common stockholders is computed by adjusting net loss attributable to common stockholders to reallocate undistributed earnings based on the potential impact of dilutive securities. Diluted net loss per share attributable to common stockholders is computed by dividing the diluted net loss attributable to common stockholders by the weighted average number of common shares outstanding for the period, including potential dilutive common shares assuming the dilutive effect of common stock equivalents. Given that the Company recorded a net loss for each of the periods presented, there is no difference between basic and diluted net loss per share since |
