Gossamer Bio Shares Plunge 60% Following Phase 3 Clinical Trial Failure

Key Facts

1Gossamer Bio lost more than 60% of its value after the Phase 3 PROSERA trial of seralutinib missed its primary endpoint.

2Levi & Korsinsky, LLP noted that the company omitted the heightened statistical threshold that made a trial miss more likely.

3CEO Faheem Hasnain had provided optimistic guidance to investors in May 2025 regarding the trial results.

Gossamer Bio (GOSS) shares plummeted by more than 60% after the company announced that its Phase 3 PROSERA trial for seralutinib failed to meet its primary endpoint. The clinical failure triggered a massive sell-off as the drug was a cornerstone of the company's development pipeline. Legal scrutiny is now mounting, with law firm Levi & Korsinsky investigating claims that the company omitted critical statistical thresholds from its public disclosures. This development follows optimistic guidance provided by CEO Faheem Hasnain in May 2025, which had previously buoyed investor expectations. Analysts suggest that the failure to reach statistical significance significantly impairs the firm's long-term valuation and market credibility. The company now faces a challenging path forward amidst potential shareholder lawsuits and a severely diminished market capitalization.