$SION

Sionna Therapeutics' stock fell 3% after-hours following a strategic reset, including a 46% workforce reduction and a shift in clinical trial focus. The company also confirmed it will not pursue SION-719. Raymond James downgraded the stock to Market Perform. The broader market showed minimal gains, with the S&P 500, Dow Jones, and Nasdaq each rising 0.1% or 0.2%.

Sionna Therapeutics (NASDAQ:SION) shares fell 3% after announcing a 46% workforce reduction and a pivot to a new cystic fibrosis drug combination, SION-451 + SION-2222, for a Phase 2a trial starting in Q1 2027. The company cited data from its PreciSION CF trial and expects $6.4M in restructuring charges, with cash runway extending into 2H 2029.

Sionna Therapeutics, Inc. (SION) filed an SEC Form 8-K — Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers: Compensatory Arrangements of Certain Officers. Exhibit 99.1 Sionna Therapeutics Announces Plans to Advance SION-451 + SION-2222 Dual Combination into Phase 2a Proof-of-Concept Trial Post hoc analyses of SION-719 PreciSION CF subset showed a mean placebo-adjusted sweat chloride reduction of up to -8.6 mmol/L consistent with NB

Vertex Pharmaceuticals (VRTX) maintains dominance in the cystic fibrosis (CF) drug market. Sionna Therapeutics (SION) reported a phase 2 trial failure for its CF drug candidate, SION-719, causing its stock to drop 90%. Vertex's CF drugs, including Trikafta and Alyftrek, now target 95% of CF patients. Vertex is also expanding into other therapeutic areas, such as gene-editing therapy Casgevy for sickle cell disease and beta-thalassemia, developed with CRISPR Therapeutics (CRSP).

Sionna Therapeutics (SION) shares fell about 92% after it said its Phase 2a trial of SION-719 in 15 cystic fibrosis adults failed to meet its main goal. The add-on drug did not significantly improve sweat chloride versus placebo, so Sionna will not advance it. SION had $268M cash. Analysts cited reduced overhang for Vertex (VRTX).

Sionna Therapeutics (NASDAQ:SION) shares fell over 90% after its Phase 2a PreciSION CF trial of SION-719 as an add-on to Vertex’s Trikafta failed its main activity endpoint, so Sionna said it will not proceed SION-719. Vertex (NASDAQ:VRTX) rose to new highs as the CF competitive overhang eased. Sionna will prioritize SION-451; Vertex cited prior strength and guidance.

Sionna Therapeutics (Nasdaq: SION) said its PreciSION CF Phase 2a study of SION-719, tested as an add-on to Trikafta, did not meet the key activity endpoint of sweat chloride reduction. The company discontinued SION-719 development in that role, according to the company. The article also references other SION updates and financial results.

Sionna Therapeutics Inc. (NASDAQ:SION) reported top-line Phase IIa data for two nucleotide binding domain 1 stabilizer programs in cystic fibrosis, and said the programs did not meet expectations. Shares fell sharply, closing Aug. 10 at $4.50, down $46.54 (91%), according to the report.

Sionna Therapeutics said its experimental cystic fibrosis pill SION-719, tested as an add-on to Vertex Pharmaceuticals’ Trikafta, showed no benefit in a Phase 2 trial. Sionna will not advance SION-719 as an add-on therapy and said it may take actions to preserve capital, including potential layoffs. Sionna’s stock fell about 90% pre-market.

Sionna Therapeutics said its Phase 2a PreciSION trial of SION-719, an add-on to Vertex’s Trikafta for cystic fibrosis, failed to meet its goal. In 15 patients, sweat chloride changed by -1.0 mmol/L, not statistically significant versus a 10 mmol/L target, and Sionna will discontinue SION-719. Sionna shares fell over 90% premarket; Vertex shares rose about 6%.