Sionna’s Phase 2a CF trial fails, shares plunge as Vertex’s Trikafta remains standard of care

Sionna Therapeutics announced that its Phase 2a cystic fibrosis trial of the NBD1 stabilizer SION-719 did not meet its primary endpoint, sending the company’s stock down more than 90% in pre‑market trading.

The 15‑patient PreciSION study, which evaluated SION-719 as an add‑on to Vertex Pharmaceuticals’ Trikafta regimen, showed a modest -1.0 mmol/L change in sweat chloride levels. The result fell far short of the 10 mmol/L reduction the trial aimed to achieve and was not statistically significant.

Following the disappointing data, Sionna said it will discontinue development of SION-719. The setback underscores the challenge of improving outcomes beyond Trikafta, which continues to be regarded as the standard of care for cystic fibrosis patients.

For Vertex, the news does not alter its market position, as Trikafta remains a highly successful therapy in the cystic fibrosis space.