Company Overview - Sionna Therapeutics, Inc. is a clinical-stage biopharmaceutical company focused on revolutionizing the treatment of cystic fibrosis (CF) by developing novel medicines that normalize the function of the cystic fibrosis transmembrane conductance regulator (CFTR) protein [3] - The company aims to deliver differentiated medicines that restore CFTR function to near-normal levels by directly stabilizing CFTR's nucleotide-binding domain 1 (NBD1), which is believed to be crucial for improving clinical outcomes and quality of life for CF patients [3] - Sionna is advancing a pipeline of small molecules designed to correct defects caused by the F508del genetic mutation in NBD1 and is also developing complementary CFTR modulators to enhance CFTR function [3] Upcoming Events - Management will present at The Citizens Life Sciences Conference on May 7, 2025, at 12:30 p.m. ET [1] - A live webcast of the presentation will be available on the company's Investor Relations website, with a replay accessible for 90 days post-event [2] Investor Relations - Sionna intends to use its Investor Relations website to disclose material nonpublic information and comply with disclosure obligations under Regulation FD, encouraging investors to monitor the website along with press releases, SEC filings, and public conference calls [4]

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K __________________________ (Mark One) x ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2024 OR o TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM____ to Commission file number 001-42504 _________________________________________________ SIONNA THERAPEUTICS, INC. (E ...

Exhibit 99.1 Sionna Therapeutics Reports Fourth Quarter and Full Year 2024 Financial Results Phase 1 MAD dosing completed for SION-451 and final MAD cohort of SION-719 planned; Interim data in healthy volunteers show potential to provide clinically meaningful benefit to CF patients. Topline data anticipated in first half of 2025 On track to initiate NBD1 Phase 2a proof-of-concept trial in combination with SOC in CF patients and combination MAD trials of an NBD1 stabilizer with a complementary modulator in h ...