Sionna Therapeutics is focusing its cystic-fibrosis drug development on a two-drug combination and plans to move it into a Phase 2 proof-of-concept trial in early 2027. The company also reported $249.8 million in cash at the end of September, which it expects to support operations into the second half of 2029.
- Next trial planned for the first quarter of 2027: The AscenSION CF study will test SION-451 with SION-2222, also known as galicaftor, in people with cystic fibrosis who have two copies of the F508del mutation. Participants will switch to the combination from Trikafta and receive treatment for 28 days.
- What the trial will measure: The open-label study will assess sweat chloride, safety and how the drugs move through the body. Sionna said the design reflects lessons from its earlier PreciSION CF study, including on dosing adherence and variability in sweat chloride measurements.
- Rationale for advancing the combination: SION-451 is an NBD1 stabilizer, while SION-2222 is a TMD1-directed CFTR corrector. Sionna said it selected the pairing based on clinical, pharmacokinetic and nonclinical evidence. The combination met safety, tolerability and pharmacokinetic objectives in a Phase 1 study in healthy volunteers.
- Additional supporting data: The company said clinical and nonclinical findings presented at the 2026 North American Cystic Fibrosis Conference supported advancing the combination and the potential of NBD1 stabilizer combinations to benefit a broad population of people with CF.
- Cash runway: Sionna had $249.8 million in cash as of September 30, 2026, and expects that balance to fund operations into the second half of 2029.
The planned move into Phase 2 puts SION-451 plus SION-2222 at the center of Sionna’s development strategy. The company’s stated cash runway extends beyond the planned start of the trial.