08:58 AM EST, 02/23/2026 (MT Newswires) -- Gossamer Bio ( GOSS ) said Monday topline results from the phase 3 Prosera study showed seralutinib improved six-minute walk distance in pulmonary arterial hypertension patients, but failed to meet the prespecified statistical threshold for the primary endpoint.

The trial's primary endpoint was placebo-adjusted change from baseline in six-minute walk distance at Week 24. Seralutinib delivered a +28.2-meter median improvement compared with +13.5 meters for placebo, the company said. This resulted in a +13.3-meter treatment effect with a p-value of 0.0320, missing the predefined significance threshold of 0.025 required for statistical success, the company added.

Secondary endpoints favored seralutinib, including reductions in NT-proBNP and measures of clinical improvement, with stronger efficacy signals observed in intermediate and high-risk patients, the company said.

Gossamer Bio ( GOSS ) said the data support discussions with the US Food and Drug Administration to determine a potential path forward.