Epizyme, Inc. presented updated safety and activity data from the Phase 1b portion of its Phase 1b/3 confirmatory study evaluating the investigational use of TAZVERIK® (tazemetostat), a first-in-class, oral, selective inhibitor of EZH2, in combination with rituximab + lenalidomide (R2) in patients with relapsed/refractory follicular lymphoma (FL) who have been treated with at least one prior systemic therapy, including patients who are rituximab-refractory and/or POD24, at the 2021 American Society of Hematology (ASH) Annual Meeting. Updated data from the Phase 1b portion of the study reported included 40 FL patients who had received treatment with tazemetostat and R2 (400 mg [n=4], 600 mg [n=18], or 800 mg [n=18]) as of the September 29, 2021 data cut-off. The findings demonstrated that the safety profile of the tazemetostat and R2 combination was consistent with the previously reported safety information in the prescribing information for both tazemetostat and R2, respectively. Additionally, there was no clear dose response for treatment-emergent adverse events (TEAEs) or dose modifications. Thirty-five of the 40 patients were evaluable for tumor assessments as of the data cut off, with 32 patients responding to treatment. The activity findings showed an objective response rate of 91.4% (37.1% complete response rate and 54.3% partial response rate). The duration of response data continue to mature as the study is ongoing. SYMPHONY-1 (EZH-302) is an international, multicenter, randomized, double-blind, active-controlled, 3-stage, biomarker-enriched, confirmatory Phase 1b/3 study, which is designed to evaluate the safety and efficacy of tazemetostat in combination with R2 in patients with relapsed or refractory FL after at least one prior line of therapy. The Phase 1b portion of the study is designed to determine the recommended Phase 3 dose, activity, and safety of tazemetostat and R2. In addition to the safety run-in analysis, the study also assessed the pharmacokinetics and continues to assess clinical activity of tazemetostat when administered in combination with R2. The Phase 1b safety run-in component evaluated tazemetostat at three dose levels (400 mg, 600 mg, and 800 mg orally twice daily) in 28-day cycles with standard-dose R2 using a 3 + 3 design. Rituximab was administered at 375 mg/m2 intravenously on days 1, 8, 15 and 22 of cycle 1, then on day 1 of cycles 2 to 5. Lenalidomide was administered at 20 mg (creatinine clearance =60 mL/min) or 10 mg (if creatinine clearance <60 mL/min) orally once daily on days 1 to 21 every 28 days for 12 cycles. In the Phase 3 component, approximately 500 patients will be randomly assigned to receive the RP3D of tazemetostat + R2 or placebo + R2. The study will also include a maintenance arm with tazemetostat or placebo following the first year of treatment with tazemetostat + R2 or placebo + R2.