Sionna to cut 46% of workforce after cystic fibrosis trial failure

Sionna Therapeutics will cut about 46% of its workforce as part of a strategic shift following the failure of an additional combination therapy trial in cystic fibrosis (CF).

According to Fierce Biotech on the 14th (local time), Sionna failed to achieve a statistically significant reduction in sweat chloride levels in a small trial in patients with homozygous F508del cystic fibrosis, adding its NBD1 stabilizer SION-719 to Vertex Pharmaceuticals' Trikafta.

Following the failure, Sionna's stock plunged 90% immediately after the announcement, effectively ending its most advanced attempt to challenge Vertex.

After a five-week post hoc analysis, the company decided to advance a combination of another NBD1 stabilizer, SION-451, and the CFTR corrector SION-2222 into a Phase 2 trial.

Sionna CEO Mike Cloonan said, "It was important to take the time to complete a comprehensive post hoc data analysis to understand the SION-719 trial results and their potential implications."

Cloonan added, "The analysis identified important factors that may have complicated the interpretation of the trial and diminished the effect of NBD1 stabilization. The post hoc analysis results and positive Phase 1 results for SION-451 and SION-2222 support advancing this combination into Phase 2a."

To focus resources on its new strategy, Sionna will reduce its workforce by about 46%, and Chief Business Officer Caroline Stark Beer will also leave the company. The company had 59 full-time employees at the start of the year.

The company said, "We will retain the core clinical, scientific, regulatory, technical and corporate capabilities needed to advance the combination therapy program."

Sionna had $268.3 million (about 359.5 billion won) in cash as of the end of June and expects the restructuring to cost about $6.4 million (about 8.6 billion won). Its cash runway is expected to extend through the second half of 2029.