Sionna Therapeutics is a clinical-stage biopharmaceutical company focused on developing novel medicines for cystic fibrosis (CF) by normalizing CFTR protein function. The company's strategy centers on stabilizing CFTR's nucleotide binding domain 1 (NBD1), a target previously considered undruggable, and developing complementary modulators. Net loss for the year ended December 31, 2025, was $75.3 million, compared to $61.7 million for 2024. Accumulated deficit reached $256.4 million as of December 31, 2025. Research and development expenses increased by $3.0 million to $60.3 million in 2025, primarily due to increased clinical programs and combination development activities. General and administrative expenses increased by $15.5 million to $28.7 million in 2025, driven by increased personnel-related costs and professional fees. SION-719, a highly potent NBD1 stabilizer, is in a Phase 2a proof-of-concept trial (PreciSION CF) as an add-on to Vertex's Trikafta, with topline data anticipated in mid-2026. Positive topline Phase 1 data for SION-719 in healthy volunteers, announced in June 2025, showed it was generally well tolerated and achieved target exposure thresholds. SION-451, another NBD1 stabilizer, is being evaluated in dual combinations with SION-2222 and SION-109 in a Phase 1 trial in healthy volunteers, with topline data expected in mid-2026. Positive topline Phase 1 data for SION-451 as a single agent, announced in June 2025, indicated it was generally well tolerated and met target exposure thresholds. Preclinical studies using the CFHBE model showed SION-719 and SION-451, in combination with other modulators or standard of care, improved CFTR channel activity to wild-type levels. The company believes its existing cash, cash equivalents, and marketable securities of $310.3 million as of December 31, 2025, will fund operations into 2028. Sionna Therapeutics completed its IPO in February 2025, raising net proceeds of $199.6 million. The company has licensed intellectual property from Sanofi and AbbVie, incurring upfront payments and potential future milestone and royalty obligations.