Zymeworks ZW191 Achieves 61% ORR and 7.6-Month PFS in Phase 1
Phase 1 data for Zymeworks’ ZW191 shows a confirmed objective response rate of 61% at 6.4–9.6 mg/kg in platinum-resistant ovarian cancer and a median progression-free survival of 7.6 months across ovarian and endometrial cohorts. The trial reported manageable safety with 55% grade ≥3 treatment-emergent adverse events and no unexpected signals.
1. Phase 1 Efficacy Results
Data from the dose-escalation phase showed a confirmed objective response rate of 61% at 6.4–9.6 mg/kg in platinum-resistant ovarian cancer and 57% in endometrial cancers, with median progression-free survival of 7.6 months and median duration of response not reached to date.
2. Safety and Tolerability
ZW191 demonstrated a manageable safety profile with 55% of patients experiencing grade ≥3 treatment-emergent adverse events, chiefly neutropenia (24%), anemia (20%) and thrombocytopenia (12%), while serious events occurred in 35% of patients and discontinuations due to adverse events stood at 20%.
3. Expansion to Dose Optimization
Enrollment in Part 2a of the Phase 1 study, evaluating 6.4 mg/kg and 9.6 mg/kg doses in ovarian cancer patients globally across North America, Europe and Asia-Pacific, has completed, setting the stage for dose selection in future registration studies.
4. Mechanism and Pipeline Impact
ZW191 is an antibody-drug conjugate targeting folate receptor α with a high drug-to-antibody ratio and proprietary topoisomerase-1 inhibitor payload, designed to broaden FRα-targeted therapy’s reach across low or heterogeneous expression tumors and strengthen Zymeworks’ oncology pipeline.