Roche said its experimental COPD therapy astegolimab delivered conflicting efficacy results, complicating plans to file for regulatory approval this year. In the 1,301-patient Phase 2b ALIENTO study, the anti-ST2 antibody achieved a statistically significant 15.4% cut in the annualised rate of moderate and severe exacerbations over 52 weeks when added to standard inhaled maintenance therapy. However, the larger 1,375-patient Phase 3 ARNASA trial showed only a 14.5% reduction, missing its primary endpoint. Safety findings were consistent with earlier studies and no new signals emerged, Roche said. Chief Medical Officer Levi Garraway called COPD the world’s third-leading cause of death and said the company will discuss the mixed data with regulators before deciding next steps. Astegolimab targets the IL-33/ST2 inflammatory pathway, an approach also being pursued by rivals after recent approvals of biologics such as Sanofi and Regeneron’s Dupixent for COPD.