Epizyme announced positive interim data from an ongoing Phase 2 study of its lead candidate tazemetostat, a potent, selective, orally available EZH2 inhibitor, as a monotherapy for patients with relapsed or refractory follicular lymphoma, or FL. The data, presented today at the 23rd Congress of the European Hematology Association in Stockholm, show that tazemetostat demonstrated meaningful clinical activity and was generally well tolerated in these heavily pre-treated patients. Interim data as of May 1, 2018 included 82 evaluable patients across two cohorts, prospectively assigned by EZH2 status. In the EZH2 activating mutation cohort, an objective response rate of 71 percent was observed; 11 percent of patients achieved a complete response, and 61 percent achieved a partial response. Twenty-nine percent achieved stable disease as best response; of those, 21 percent are still on study with the potential to respond. All patients in this cohort experienced reduction in tumor burden, and no patients experienced progressive disease as best response. At the time of this analysis, the median progression-free survival was 49 weeks and the median duration of response was 32 weeks, and both endpoints continue to mature. In the fully-enrolled cohort of FL patients with wild-type EZH2, the ORR was 33 percent; six percent achieved a CR, and 28 percent achieved a PR. An additional 31 percent of patients achieved SD as best response, including one patient who is still receiving treatment. At the time of this analysis, the median PFS was 30 weeks and median DOR was 76 weeks. The median DOR figure continues to mature, with more than half of the responders still on therapy.
