Gossamer Bio Shares Crash After Phase 3 Trial Misses Primary Goal

The San Diego-based biotechnology firm reported that its late-stage trial evaluating seralutinib for the treatment of Pulmonary Arterial Hypertension (PAH) did not achieve the mathematical significance required for its primary endpoint. While the study demonstrated a placebo-adjusted improvement of 13.3 meters in a six-minute walk distance test at week 24, the result fell short of the prespecified threshold.

Secondary Findings and Clinical Subgroups

Despite the primary failure, management emphasized that the trial’s broader data set remains encouraging. According to the company, all four key secondary endpoints favored the drug over the placebo group in the overall population. Additionally, the study identified clinically meaningful improvements among intermediate- and high-risk patients, a demographic that often requires more aggressive intervention.

Gossamer Bio saw its stock price drop to 38 cents as investors weighed the uncertainty of the drug's regulatory future. The company stated it intends to meet with the Food and Drug Administration (FDA) to discuss these results and determine a viable path forward for the seralutinib program.