Zymeworks Reports Dose-Dependent Phase 1 Results for ZW191 in Ovarian Cancer

Zymeworks presented Phase 1 dose-optimization data for ZW191 in platinum-resistant ovarian cancer, comparing 6.4 and 9.6 mg/kg every three weeks in 80 patients. Among response-evaluable high-grade serous patients, confirmed response rates were 64.5% and 55.3%, respectively, with six-month progression-free survival at 61% in both groups. Severe treatment-related adverse events were less frequent at the lower dose (22% vs. 44%), and the company said the results will guide further dose selection.

The Phase 1 dose-optimization portion randomized 80 patients with platinum-resistant ovarian cancer to ZW191 every three weeks at 6.4 or 9.6 mg/kg. After a median seven months of follow-up, confirmed responses among assessable high-grade serous patients were 64.5% and 55.3%; disease control was 100% and 92.1%. Responses occurred across folate receptor alpha expression categories.

Six-month progression-free survival was 61% in both groups, while median progression-free survival was 7.9 and 9.8 months. Grade 3 or higher treatment-related adverse events affected 22% and 44%; dose reductions occurred in 5% and 33%, and discontinuations in 14% and 19%. No treatment-emergent deaths were reported, and 45% remained on treatment as progression-free survival data mature.