Summary of Significant Accounting Policies	6 Months Ended
Jun. 30, 2025
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies (a)Basis of Presentation and Principles of Consolidation The accompanying Condensed Consolidated Financial Statements have been prepared in accordance with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. These statements, however, are condensed and do not include all disclosures required by accounting principles generally accepted in the U.S. (“GAAP”) for complete financial statements and should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2024 as filed with the Securities and Exchange Commission (“SEC”) on March 31, 2025. In the opinion of the management of the Company, the unaudited Condensed Consolidated Financial Statements contain all adjustments (all of which were considered normal and recurring) necessary for a fair statement of the Company’s financial position at June 30, 2025; the results of operations for the three and six-month periods ended June 30, 2025 and 2024; stockholders' equity (deficit) for the three and six-month periods ended June 30, 2025 and 2024; and the cash flows for the six-month periods ended June 30, 2025 and 2024. The Condensed Consolidated Balance Sheet at December 31, 2024 was derived from audited annual financial statements but does not contain all of the footnote disclosures from the annual financial statements. The Company’s Condensed Consolidated Financial Statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the ordinary course of business. In accordance with FASB ASU No. 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (Subtopic 205-40), the Company has concluded there are conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the Condensed Consolidated Financial Statements are issued. The Condensed Consolidated Financial Statements do not include any adjustments that might result from the outcome of this uncertainty. (b)Use of Estimates and Assumptions The preparation of the Company’s Condensed Consolidated Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts and disclosure of revenue, expenses and certain assets and liabilities at the balance sheet date. Such estimates include the performance obligations under the Company’s collaboration agreements; the collectability of receivables; and the value of certain liabilities. Actual results may differ from such estimates. These interim results are not necessarily indicative of results to be expected for a full year or subsequent interim periods. (c) Cash Equivalents and Restricted Cash Cash equivalents consist of highly liquid investments purchased with original maturities of three months or less. The Company classified $0.5 million of its cash as restricted cash as of both June 30, 2025 and December 31, 2024. These amounts represent the security deposit associated with the Company’s Lexington, Massachusetts headquarters. (d)Leases The Company determines if an arrangement is a lease at contract inception. The Company made an accounting policy election to not recognize leases with an initial term of 12 months or less within its Condensed Consolidated Balance Sheets and to recognize those lease payments on a straight-line basis in its Condensed Consolidated Statements of Operations and Comprehensive Loss over the lease term. Operating lease assets represent the Company's right to use an underlying asset for the lease term and operating lease liabilities represent its obligation to make lease payments arising from the lease. Operating lease assets and liabilities are recognized at the commencement date of the lease based upon the present value of lease payments over the lease term. When determining the lease term, the Company includes options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. As the Company's lease does not provide an implicit interest rate, the Company uses its incremental borrowing rate, which is based on rates that would be incurred to borrow on a collateralized basis over a term equal to the lease payments in a similar economic environment, in determining the present value of lease payments. The lease payments used to determine the operating lease asset may include lease incentives and stated rent increases and are recognized as an operating lease right-of-use asset in the Condensed Consolidated Balance Sheets. The Company's lease agreements may include both lease and non-lease components, which may be accounted for as a single lease component when the payments are fixed. Variable payments included in the lease agreement are expensed as incurred. The Company's operating lease is reflected in operating lease right-of-use asset and operating lease liability in the Condensed Consolidated Balance Sheets. Lease expense for lease payments is recognized on a straight-line basis over the lease term. (e)Other Assets Other assets consist of long-term prepayments and deposits. (f)Revenue Recognition The Company applies the revenue recognition guidance in accordance with FASB Codification Topic 606, Revenue from Contracts with Customers. The Company recognizes royalty revenues related to Genentech’s and Roche’s sales of Erivedge. For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and where the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). The Company expects to continue recognizing royalty revenue from Genentech’s sales of Erivedge in the U.S. and Roche's sales of Erivedge outside of the U.S. (see Note 7, Research and Development Collaborations). However, a significant portion of Erivedge royalties will be paid to the Purchasers pursuant to the Oberland Purchase Agreement (see Note 6, Liability Related to the Sale of Future Royalties). (g)Segment Reporting The Company has determined that it operates in a single reportable segment, which is the research and development of innovative drug candidates for the treatment of human cancer. (h)New Accounting Pronouncements Issued, Not Yet Adopted In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which requires disclosure of disaggregated income taxes paid, prescribes standard categories for the components of the effective tax rate reconciliation, and modifies other income tax-related disclosures. ASU No. 2023-09 is effective for fiscal years beginning after December 15, 2024 and allows for adoption on a prospective basis, with a retrospective option. Early adoption is permitted. The Company is currently evaluating the impact of the ASU on the income tax disclosures within the Consolidated Financial Statements. In November 2024, the FASB issued ASU-2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Topic 220): Disaggregation of Income Statement Expenses. The ASU requires additional disclosures of the nature of the expenses included in the income statement, including disaggregation of the expense captions presented on the Consolidated Statements of Operations into specific categories. ASU No. 2024-03 is effective for fiscal years beginning after December 15, 2026, and for interim periods beginning after December 15, 2027 and allows for adoption on a prospective basis, with a retrospective option. Early adoption is permitted. The Company is currently evaluating the impact of the ASU on the Condensed Consolidated Financial Statement disclosures. In July 2025, the One Big Beautiful Bill Act (“OBBB”) was enacted in the U.S. The OBBB includes significant provisions, such as the permanent extension of certain expiring provisions of the Tax Cuts and Jobs Act, restoration of favorable tax treatment for certain business provisions including the expensing of domestic research and development expenditures, and modifications to the international tax framework. Certain provisions will take effect beginning in 2026, while others apply retroactively to January 1, 2025. The Company is currently evaluating the impact on the income tax disclosures within the Consolidated Financial Statements.

The accompanying Condensed Consolidated Financial Statements have been prepared in accordance with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. These statements, however, are condensed and do not include all disclosures required by accounting principles generally accepted in the U.S. (“GAAP”) for complete financial statements and should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2024 as filed with the Securities and Exchange Commission (“SEC”) on March 31, 2025.

In the opinion of the management of the Company, the unaudited Condensed Consolidated Financial Statements contain all adjustments (all of which were considered normal and recurring) necessary for a fair statement of the Company’s financial position at June 30, 2025; the results of operations for the three and six-month periods ended June 30, 2025 and 2024; stockholders' equity (deficit) for the three and six-month periods ended June 30, 2025 and 2024; and the cash flows for the six-month periods ended June 30, 2025 and 2024. The Condensed Consolidated Balance Sheet at December 31, 2024 was derived from audited annual financial statements but does not contain all of the footnote disclosures from the annual financial statements.

The Company’s Condensed Consolidated Financial Statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the ordinary course of business. In accordance with FASB ASU No. 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (Subtopic 205-40), the Company has concluded there are conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the Condensed Consolidated Financial Statements are issued. The Condensed Consolidated Financial Statements do not include any adjustments that might result from the outcome of this uncertainty.

The preparation of the Company’s Condensed Consolidated Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts and disclosure of revenue, expenses and certain assets and liabilities at the balance sheet date. Such estimates include the performance obligations under the Company’s collaboration agreements; the collectability of receivables; and the value of certain liabilities. Actual results may differ from such estimates. These interim results are not necessarily indicative of results to be expected for a full year or subsequent interim periods.

The Company classified $0.5 million of its cash as restricted cash as of both June 30, 2025 and December 31, 2024. These amounts represent the security deposit associated with the Company’s Lexington, Massachusetts headquarters.

The Company determines if an arrangement is a lease at contract inception. The Company made an accounting policy election to not recognize leases with an initial term of 12 months or less within its Condensed Consolidated Balance Sheets and to recognize those lease payments on a straight-line basis in its Condensed Consolidated Statements of Operations and Comprehensive Loss over the lease term. Operating lease assets represent the Company's right to use an underlying asset for the lease term and operating lease liabilities represent its obligation to make lease payments arising from the lease. Operating lease assets and liabilities are recognized at the commencement date of the lease based upon the present value of lease payments over

As the Company's lease does not provide an implicit interest rate, the Company uses its incremental borrowing rate, which is based on rates that would be incurred to borrow on a collateralized basis over a term equal to the lease payments in a similar economic environment, in determining the present value of lease payments.

The lease payments used to determine the operating lease asset may include lease incentives and stated rent increases and are recognized as an operating lease right-of-use asset in the Condensed Consolidated Balance Sheets. The Company's lease agreements may include both lease and non-lease components, which may be accounted for as a single lease component when the payments are fixed. Variable payments included in the lease agreement are expensed as incurred.

The Company's operating lease is reflected in operating lease right-of-use asset and operating lease liability in the Condensed Consolidated Balance Sheets. Lease expense for lease payments is recognized on a straight-line basis over the lease term.

The Company recognizes royalty revenues related to Genentech’s and Roche’s sales of Erivedge. For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and where the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). The Company expects to continue recognizing royalty revenue from Genentech’s sales of Erivedge in the U.S. and Roche's sales of Erivedge outside of the U.S. (see Note 7, Research and Development Collaborations). However, a significant portion of Erivedge royalties will be paid to the Purchasers pursuant to the Oberland Purchase Agreement (see Note 6, Liability Related to the Sale of Future Royalties).

In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which requires disclosure of disaggregated income taxes paid, prescribes standard categories for the components of the effective tax rate reconciliation, and modifies other income tax-related disclosures. ASU No. 2023-09 is effective for fiscal years beginning after December 15, 2024 and allows for adoption on a prospective basis, with a retrospective option. Early adoption is permitted. The Company is currently evaluating the impact of the ASU on the income tax disclosures within the Consolidated Financial Statements.

In November 2024, the FASB issued ASU-2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Topic 220): Disaggregation of Income Statement Expenses. The ASU requires additional disclosures of the nature of the expenses included in the income statement, including disaggregation of the expense captions presented on the Consolidated Statements of Operations into specific categories. ASU No. 2024-03 is effective for fiscal years beginning after December 15, 2026, and for interim periods beginning after December 15, 2027 and allows for adoption on a prospective basis, with a retrospective option. Early adoption is permitted. The Company is currently evaluating the impact of the ASU on the Condensed Consolidated Financial Statement disclosures.