Sionna Therapeutics Discontinues Cystic Fibrosis Drug Following Unfavorable Data Data, Stock Tanks

Clinical-stage biopharmaceutical company Sionna Therapeutics Inc. (NASDAQ: SION ) announced topline clinical trial results from two nucleotide binding domain 1 (NBD1) stabilizer candidate programs targeting cystic fibrosis (CF). The findings indicated that its PreciSION CF Phase 2a trial assessing SION-719 missed its key primary activity target, leading the company to halt further advancement of SION-719 as an add-on therapy. SION-719 Fails Primary Endpoint In Phase 2a Trial In the PreciSION CF Phase 2a proof-of-concept study, SION-719 was evaluated in combination with Trikafta (elexacaftor/tezacaftor/ivacaftor) among CF participants.

7), falling short of its activity target. Sionna highlighted potential confounders, such as unexpected variability in individual sweat chloride levels and differences in Trikafta exposure across the SION-719 and placebo periods. The firm received the data on August 7, 2026, and is actively analyzing these elements. Read Also: Arcturus Picks Thermo Fisher To Support Cystic Fibrosis Therapy Although SION-719 proved generally well tolerated over 14 days with mostly mild-to-moderate treatment-emergent adverse events and no serious adverse events or liver function trends, Sionna will not advance the candidate further.

Phase 1 Trial Meets Safety Objectives for Dual Combinations Separately, Sionna shared results from a Phase 1 study of SION-451 in proprietary dual combinations with SION-2222 or SION-109 in healthy subjects. The trial fulfilled its target safety, tolerability, and pharmacokinetic objectives. Based on overall data and target coverage, the SION-451 and SION-2222 pairing was chosen as the preferred dual-combination regimen. SION-451 twice-daily paired with SION-2222 once-daily was generally well tolerated, with one discontinuation caused by a rash.

In twice-daily cohorts for both drugs, most adverse events were mild to moderate, though two subjects discontinued due to elevated liver function tests and flu-like symptoms. SION-451 and SION-109 combinations were also generally well tolerated, and Sionna is evaluating future steps. 86 at the time of publication on Monday. The stock is trading at a new 52-week low, according to Pro data.

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