Sionna Therapeutics drops SION-719 cystic fibrosis add-on after Phase 2a trial misses
Sionna Therapeutics reported that its Phase 2a PreciSION CF trial of SION-719 added to standard of care did not meet its key activity endpoint, and the company will not advance SION-719 as an add-on. The company identified SION-451 with SION-2222 as the preferred dual combination from a Phase 1 healthy volunteer study, and it plans to preserve capital while it evaluates next steps.
Key points
- PreciSION CF Phase 2a trial showed a -1.0 mmol/L mean placebo-adjusted sweat chloride change (p=0.7), missing the key activity endpoint.
- Company is not advancing SION-719 as an add-on to standard of care; topline data were received Friday, August 7, 2026.
- Phase 1 trial identified SION-451 + SION-2222 as the preferred dual combination; 120 participants were dosed across both dual combinations.
- Sionna ended Q2 with approximately $268.3 million in cash, cash equivalents and marketable securities and plans actions to preserve capital.
The filing
Written by AI on Nov 9, 2026, 11:46 AM ET, from this filing only. Written later: this filing was briefed after the fact, when past filings were added to the site, so the brief may be read with hindsight; the filing itself is the record of what was known on August 10, 2026.
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