Gossamer Bio has reported topline data from the Phase III PROSERA study evaluating seralutinib in patients with pulmonary arterial hypertension (PAH).
Chiesi Group and the company are jointly developing seralutinib as part of a global partnership agreement.
The trial included 390 patients with World Health Organization (WHO) Functional Class II or III PAH, who were randomised into either the seralutinib or placebo arms while maintaining background PAH therapy.
The global registrational, placebo-controlled, double-blind trial provided blinded treatment to patients for up to 48 weeks. Of those enrolled, 197 received seralutinib and 193 received placebo.
Background triple or quadruple PAH therapy was used by 55% of participants, and 61% were on background prostacyclin therapy. Baseline characteristics were generally well balanced between the groups.
At week 24, median change in six-minute walk distance (6MWD) from baseline for the seralutinib group was +28.2m, compared to +13.5m for placebo. The estimated Hodges-Lehmann treatment effect was +13.3m.
This result did not achieve the prespecified statistical threshold for the primary endpoint, which means that p values for key secondary endpoints cannot be assessed for statistical significance. However, all four key secondary endpoints favoured seralutinib over placebo in the overall population.
In a prespecified subgroup of intermediate and high-risk patients (n=234), as defined by a REVEAL 2 Lite Risk Score greater than six at screening, seralutinib achieved a placebo-adjusted improvement of +20.0m in 6MWD. Three out of four secondary endpoints in this subgroup showed p-values below 0.0125.
Gossamer Bio chairman, co-founder, and CEO Faheem Hasnain said: “While we are disappointed to have narrowly missed the stringent prespecified statistical threshold for our primary endpoint, the result still clears the traditional 0.05 p-value, and we believe these data clearly demonstrate seralutinib is an active drug in patients with PAH.
“We are also pleased by the clinically meaningful improvements observed in intermediate- and high-risk patients who are at an increased risk of significant morbidity and mortality events and represent a population with a high unmet need.
“From a clinical development perspective, this is not a narrow or exploratory finding. Seralutinib has once again demonstrated a statistically robust and clinically meaningful signal in higher risk patients, consistent with the TORREY Study, which is a clearly defined and readily identifiable population. This finding is compelling on its own.”
