Sionna Therapeutics ended its cystic fibrosis add-on strategy after a Phase 2 trial failed to show benefit when paired with Vertex’s Trikafta. In the Precision CF study, Sionna’s SION-719 plus Trikafta did not yield a statistically significant placebo-adjusted change in sweat chloride levels compared with Trikafta alone. Sionna also said it will take steps to preserve capital while assessing next steps after the disappointing clinical readout. The failure quickly reshaped investor expectations for Sionna’s ability to challenge Vertex’s CF franchise, and the company’s shares fell sharply in response. Sionna had framed a larger sweat chloride difference as clinically meaningful, but reported the observed separation fell short of its own target. —