Wire · opportunities
After missed endpoint, Gossamer and Chiesi pull the plug on PAH drug collaboration
◆ Sectors
◆ Geography
◆ Source
◆ Verified
Fusion42 · 27 July 2026 · Fusion42 review
Gossamer Bio has terminated its $486 million collaboration with Chiesi on the PAH drug seralutinib, regaining worldwide rights after the candidate missed its primary endpoint in phase 3 but showed secondary efficacy signals. The company plans to file an NDA with the FDA in September based on the trial data and a pre-NDA meeting characterization that positioned statistical significance as a review issue rather than a filing barrier.
This Wire brief sits within Fusion42's coverage of Biotech. Wire is Fusion42's founder-focused intelligence feed: each story is connected to the funds and startups it names — every one with a live profile on Raise or Scout — so founders can follow the capital and the momentum behind the headline rather than just the headline itself. Wire analysis is one of the live surfaces Arthur reasons over.
◆ ◆ The Wire takeaway
Gossamer has discovered the FDA will accept a missed primary endpoint if secondary data shows the drug works in a harder subgroup. If you're building a rare disease therapy that fails its primary but shows real activity in a subset, the regulatory path just opened—talk to your FDA contact about how to frame subgroup efficacy as a filing strength, not a weakness.
◆ Related on Wire
◆ Topics