Organization and Basis of Presentation	3 Months Ended
Mar. 31, 2026
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	Note 1. Organization and Basis of Presentation Description of the Business Septerna, Inc. (“Septerna” or the “Company”) is a clinical-stage biotechnology company with a world-class team of G protein-coupled receptor (“GPCR”) experts and drug developers advancing cutting-edge science to unlock the full potential of GPCR therapies for patients with significant unmet needs. The Company’s proprietary Native Complex Platform® is designed to enable new approaches to GPCR drug discovery and has led to the development of a diverse pipeline of novel oral small molecule drug candidates. The Company is advancing programs in endocrinology, immunology and inflammation, metabolic diseases and additional therapeutic areas, both independently and with partners. The Company’s proprietary Native Complex Platform® replicates the natural structure, function, and dynamics of GPCRs outside of cells at an industrial scale. The Company’s foundational technologies enable it to isolate, purify, and reconstitute full-length, properly folded GPCR proteins within ternary complexes with ligands and transducer proteins in a lipid bilayer that mimics the cell membrane. The Company then applies state-of-the-art discovery tools and technologies to these defined and tunable protein complexes to structurally design, screen for, and optimize potential product candidates. Leveraging its platform, the Company has transformed GPCR oral small molecule drug discovery to an industrialized and iterative structure-based drug design approach to expand the landscape of druggable GPCR targets with novel oral small molecule medicines for patients. The Company’s Native Complex Platform® is designed to enable it to target certain GPCRs for the first time, uncover novel binding pockets for validated receptors, and pursue a wide spectrum of pharmacologies, including agonists, antagonists, and allosteric modulators, to affect GPCR signaling in different ways to achieve desired therapeutic effects. The Company was incorporated in Delaware in December 2019, under the name GPCR NewCo, Inc. In June 2021, the Company changed its name to Septerna, Inc. The Company is headquartered in South San Francisco, California. Basis of Presentation The accompanying unaudited interim condensed financial statements have been prepared in conformity with generally accepted accounting principles in the United States of America (“U.S. GAAP”) stated in U.S. dollars and include all adjustments necessary for the fair presentation of the Company’s interim financial information. The condensed balance sheet data at December 31, 2025 was derived from the audited financial statements included in Septerna’s Annual Report on Form 10-K for the year ended December 31, 2025 as filed with the Securities and Exchange Commission (“SEC”) on March 9, 2026. These interim unaudited condensed financial statements should be read in conjunction with the audited financial statements and related notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2025. Liquidity and Capital Resources The accompanying unaudited condensed financial statements have been prepared assuming the Company will continue as a going concern, which assumes that the Company will realize its assets and satisfy its liabilities in the normal course of business. As of March 31, 2026, the Company had cash, cash equivalents and marketable securities of $522.1 million, which the Company believes will be sufficient to fund its planned operations for a period of, at least, twelve months following the date of filing of this report. Significant Accounting Policies During the three months ended March 31, 2026, there were no changes to the Company’s significant accounting policies as described in Note 2 of the audited financial statements for the year ended December 31, 2025. Recently Adopted Accounting Pronouncements In July 2025, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2025-05, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets, which provides a practical expedient that assumes that current conditions as of the balance sheet date do not change for the remaining life of the asset in developing reasonable and supportable forecasts during the application of the current expected credit loss model for current accounts receivable and current contract assets arising from transactions under ASC 606. ASU 2025-05 is effective for fiscal years beginning after December 15, 2025 and interim reporting periods within those annual reporting periods. Early adoption is permitted. The Company determined there is no impact of adopting ASU 2025-05 as it does not develop forecasts as part of estimating expected credit losses. Accounting Pronouncements Not Yet Adopted From time to time, new accounting pronouncements are issued by the FASB, under its Accounting Standards Codification (“ASC”) or other standard setting bodies, and adopted by the Company as of the specified date. In November 2024, the FASB issued ASU No. 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses, an accounting standard update that requires the Company to disclose more detailed information about the types of expenses (including employee compensation, depreciation, and amortization) included in each relevant income statement expense caption. The ASU is effective for fiscal years beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. Early adoption is permitted. The Company is currently evaluating the impact that this update will have on its disclosures.

Septerna, Inc. (“Septerna” or the “Company”) is a clinical-stage biotechnology company with a world-class team of G protein-coupled receptor (“GPCR”) experts and drug developers advancing cutting-edge science to unlock the full potential of GPCR therapies for patients with significant unmet needs. The Company’s proprietary Native Complex Platform® is designed to enable new approaches to GPCR drug discovery and has led to the development of a diverse pipeline of novel oral small molecule drug candidates. The Company is advancing programs in endocrinology, immunology and inflammation, metabolic diseases and additional therapeutic areas, both independently and with partners.

The Company’s proprietary Native Complex Platform® replicates the natural structure, function, and dynamics of GPCRs outside of cells at an industrial scale. The Company’s foundational technologies enable it to isolate, purify, and reconstitute full-length, properly folded GPCR proteins within ternary complexes with ligands and transducer proteins in a lipid bilayer that mimics the cell membrane. The Company then applies state-of-the-art discovery tools and technologies to these defined and tunable protein complexes to structurally design, screen for, and optimize potential product candidates. Leveraging its platform, the Company has transformed GPCR oral small molecule drug discovery to an industrialized and iterative structure-based drug design approach to expand the landscape of druggable GPCR targets with novel oral small molecule medicines for patients. The Company’s Native Complex Platform® is designed to enable it to target certain GPCRs for the first time, uncover novel binding pockets for validated receptors, and pursue a wide spectrum of pharmacologies, including agonists, antagonists, and allosteric modulators, to affect GPCR signaling in different ways to achieve desired therapeutic effects.

The Company was incorporated in Delaware in December 2019, under the name GPCR NewCo, Inc. In June 2021, the Company changed its name to Septerna, Inc. The Company is headquartered in South San Francisco, California.

Basis of Presentation

The accompanying unaudited interim condensed financial statements have been prepared in conformity with generally accepted accounting principles in the United States of America (“U.S. GAAP”) stated in U.S. dollars and include all adjustments necessary for the fair presentation of the Company’s interim financial information.

The condensed balance sheet data at December 31, 2025 was derived from the audited financial statements included in Septerna’s Annual Report on Form 10-K for the year ended December 31, 2025 as filed with the Securities and Exchange Commission (“SEC”) on March 9, 2026. These interim unaudited condensed financial statements should be read in conjunction with the audited financial statements and related notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2025.

Liquidity and Capital Resources

The accompanying unaudited condensed financial statements have been prepared assuming the Company will continue as a going concern, which assumes that the Company will realize its assets and satisfy its liabilities in the normal course of business.

As of March 31, 2026, the Company had cash, cash equivalents and marketable securities of $522.1 million, which the Company believes will be sufficient to fund its planned operations for a period of, at least, twelve months following the date of filing of this report.

Significant Accounting Policies

During the three months ended March 31, 2026, there were no changes to the Company’s significant accounting policies as described in Note 2 of the audited financial statements for the year ended December 31, 2025.

Recently Adopted Accounting Pronouncements

In July 2025, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2025-05, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets, which provides a practical expedient that assumes that current conditions as of the balance sheet date do not change for the remaining life of the asset in developing reasonable and supportable forecasts during the application of the current expected credit loss model for current accounts receivable and current contract assets arising from transactions under ASC 606. ASU 2025-05 is effective for fiscal years beginning after December 15, 2025 and interim reporting periods within those annual reporting periods. Early adoption is permitted. The Company determined there is no impact of adopting ASU 2025-05 as it does not develop forecasts as part of estimating expected credit losses.

Accounting Pronouncements Not Yet Adopted

From time to time, new accounting pronouncements are issued by the FASB, under its Accounting Standards Codification (“ASC”) or other standard setting bodies, and adopted by the Company as of the specified date.

In November 2024, the FASB issued ASU No. 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses, an accounting standard update that requires the Company to disclose more detailed information about the types of expenses (including employee compensation, depreciation, and amortization) included in each relevant income statement expense caption. The ASU is effective for fiscal years beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. Early adoption is permitted. The Company is currently evaluating the impact that this update will have on its disclosures.