Vertex Shares Rise as Rival Sionna's Cystic-Fibrosis Trial Fails to Meet Endpoint
By Anvee Bhutani
Vertex Pharmaceuticals shares rose after rival Sionna Therapeutics said a midstage trial of its cystic-fibrosis treatment failed to meet its primary endpoint, sending Sionna shares tumbling.
Shares of Vertex were recently up 7% at $530.83. Shares of Sionna plummeted 92% to $4.19.
Sionna said its SION-719 treatment showed a placebo-adjusted reduction of 1.0 millimole per liter in sweat chloride levels, missing the trial's primary endpoint. The company cited potential confounders, including higher-than-expected variability in sweat chloride levels and differences in Trikafta exposure.
Sionna said it is not advancing SION-719 and is evaluating the data to determine next steps for its SION-451 dual-combination program.
Investors think this may reinforce Vertex's dominant position in the cystic-fibrosis market, where its therapies include Trikafta and Alyftrek. Cantor Fitzgerald analysts said the Sionna results remove an overhang from Vertex shares and raise questions about Sionna's development approach.
Write to Anvee Bhutani at anvee.bhutani@wsj.com
(END) Dow Jones Newswires
August 10, 2026 11:18 ET (15:18 GMT)
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