Nature of the Business	3 Months Ended
Mar. 31, 2026
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of the Business	Nature of the Business Organization Sionna Therapeutics, Inc. (the “Company”), formerly known as Sling Therapeutics, Inc., was incorporated in Delaware in August 2019 and is headquartered in Waltham, Massachusetts. The Company is a clinical-stage biopharmaceutical company on a mission to revolutionize the current treatment paradigm for cystic fibrosis (“CF”) patients by developing novel medicines that normalize the function of the cystic fibrosis transmembrane conductance regulator protein to deliver clinically meaningful benefit to CF patients. Risks and Uncertainties The Company is subject to a number of risks common to other companies in the biotechnology industry, including but not limited to, development by competitors of new technological innovations, risks of failure of preclinical studies and clinical trials, development and manufacturing of product candidates, obtaining regulatory approval for product candidates, competition from substitute products, the need to successfully commercialize and gain market acceptance of its product candidates, protection of proprietary technology, dependence on key personnel, the ability to attract and retain qualified employees, reliance on third party organizations, compliance with government regulations, and the need to obtain additional financing. Product candidates currently under development will require significant additional research and development efforts, including extensive clinical testing and regulatory approval, prior to commercialization. These efforts will require significant amounts of additional capital, adequate personnel infrastructure, and extensive compliance reporting capabilities. Even if the Company’s development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales. Liquidity and Going Concern The Company has incurred annual net operating losses and has generated negative operating cash flows in every year since inception. As of March 31, 2026, the Company had an accumulated deficit of $283.1 million. The Company expects its operating losses to continue into the foreseeable future as it continues to pursue its research and development efforts. The Company has evaluated whether 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 these condensed consolidated financial statements are issued. The Company believes that its existing cash, cash equivalents and marketable securities of $289.9 million as of March 31, 2026, will be sufficient to allow the Company to fund operations beyond twelve months from the date that the financial statements are issued. In March 2026, the Company entered into a sales agreement with Leerink Partners LLC (“Leerink”), under which the Company, from time to time, may issue and sell shares of the Company’s common stock through an "at-the-market" equity offering program under which Leerink is acting as sales agent, for aggregate gross sale proceeds of up to $250.0 million. As of March 31, 2026, the Company has not sold any shares of common stock under the sales agreement.

Sionna Therapeutics, Inc. (the “Company”), formerly known as Sling Therapeutics, Inc., was incorporated in Delaware in August 2019 and is headquartered in Waltham, Massachusetts. The Company is a clinical-stage biopharmaceutical company on a mission to revolutionize the current treatment paradigm for cystic fibrosis (“CF”) patients by developing novel medicines that normalize the function of the cystic fibrosis transmembrane conductance regulator protein to deliver clinically meaningful benefit to CF patients.

The Company is subject to a number of risks common to other companies in the biotechnology industry, including but not limited to, development by competitors of new technological innovations, risks of failure of preclinical studies and clinical trials, development and manufacturing of product candidates, obtaining regulatory approval for product candidates, competition from substitute products, the need to successfully commercialize and gain market acceptance of its product candidates, protection of proprietary technology, dependence on key personnel, the ability to attract and retain qualified employees, reliance on third party organizations, compliance with government regulations, and the need to obtain additional financing. Product candidates currently under development will require significant additional research and development efforts, including extensive clinical testing and regulatory approval, prior to commercialization. These efforts will require significant amounts of additional capital, adequate personnel infrastructure, and extensive compliance reporting capabilities. Even if the Company’s development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales.

The Company has incurred annual net operating losses and has generated negative operating cash flows in every year since inception. As of March 31, 2026, the Company had an accumulated deficit of $283.1 million. The Company expects its operating losses to continue into the foreseeable future as it continues to pursue its research and development efforts.

The Company has evaluated whether 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 these condensed consolidated financial statements are issued. The Company believes that its existing cash, cash equivalents and marketable securities of $289.9 million as of March 31, 2026, will be sufficient to allow the Company to fund operations beyond twelve months from the date that the financial statements are issued.

In March 2026, the Company entered into a sales agreement with Leerink Partners LLC (“Leerink”), under which the Company, from time to time, may issue and sell shares of the Company’s common stock through an "at-the-market" equity offering program under which Leerink is acting as sales agent, for aggregate gross sale proceeds of up to $250.0 million. As of March 31, 2026, the Company has not sold any shares of common stock under the sales agreement.