Sionna Therapeutics' cystic fibrosis drug, SION-719, failed to meet the primary endpoint in a Phase 2a trial, resulting in a 90% drop in its stock price and a 92% decline in premarket trading on August 10, 2026.
The trial showed a placebo-adjusted sweat chloride change of -1.0 mmol/L with a p-value of 0.7, indicating no statistically significant benefit when added to Vertex's Trikafta cystic fibrosis treatment.
Vertex Pharmaceuticals' shares rose 7% to $530.83 as the failure of SION-719, a potential competitor to Trikafta, removed a near-term threat to its dominance in the cystic fibrosis market.
Sources:
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