Phase 2 Multicenter Study of Tazemetostat, an EZH2 Inhibitor, in Patients with Relapsed or Refractory Follicular Lymphoma

• Published in: Blood 2019-11, Vol.134 (Supplement_1), p.123-123
• Main Authors: Morschhauser, Franck, Tilly, Herve, Chaidos, Aristeidis, Phillips, Tycel J., Ribrag, Vincent, Campbell, Philip, Gandhi Laurent, Damaj, Jurczak, Wojciech, McKay, Pamela, Opat, Stephen, Radford, John, Whalen, Jennifer, Rajarethinam, Anand, Navia, Susan Benedict, Adib, Deyaa, Salles, Gilles
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2019-128096

Introduction: Relapsed/refractory (R/R) follicular lymphoma (FL) remains a difficult-to-treat condition, with limited treatment options. New, tolerable treatments with unique mechanisms of action are needed, especially for high-risk patients whose disease progresses within 24 months of diagnosis (POD24). The epigenetic regulator EZH2 catalyzes the histone 3 lysine 27 trimethylation (H3K27m3) gene suppressive mark, which is essential for BCL6-driven germinal center (GC) formation. Conversely, a reduction in EZH2 catalytic activity is required for centroblast differentiation and initiation of the GC exit program. Activating mutations (MT) in EZH2, present in ~20% of FL patients, and enhanced H3K27me3 prevent GC exit, resulting in GC hyperplasia and lymphomagenesis. Tazemetostat, an investigational, selective, oral EZH2 inhibitor, has demonstrated durable, single-agent, antitumor activity in R/R FL patients with MT or wild-type (WT) EZH2. Herein, we report newly emerging interim efficacy and safety data from the MT and WT cohorts and the POD24 subgroup. Methods: This open-label, multicenter, phase 2 study (NCT01897571) evaluated tazemetostat 800 mg administered orally twice daily in patients with MT or WT EZH2 R/R FL (Grade 1-3b). Key inclusion criteria included age ≥18 years, Eastern Cooperative Oncology Group performance status of 0-2, ≥2 prior treatment regimens, and measurable disease per 2007 IWG-NHL criteria. The primary endpoint was objective response rate (complete response + partial response). Secondary endpoints included progression-free survival and safety. The POD24 subgroup was composed of patients experiencing disease progression or relapse within 24 months of diagnosis or the start of frontline treatment with immunochemotherapy. Results: As of June 7, 2019, interim data were available for 99 patients (MT EZH2, n=45 [POD24, n=17; 38%]; WT EZH2, n=54 [POD24, n=30; 56%]). Of the 33 patients in the MT cohort with an objective response, 15 (45%) had a response at ≥6 months, 7 (21%) at ≥12 months, and 4 (12%) at ≥16 months. Of the 18 patients in the WT cohort with an objective response, 15 (83%) had a response at ≥6 months, 9 (50%) at ≥12 months, and 6 (33%) at ≥16 months. Data from the MT cohort continue to mature, with 11 (24%) patients enrolled in the past year and 17 (38%) patients still on treatment. Updated data from the fully enrolled MT cohort, and sub-group analyses from both WT and MT cohort, will be presented. Interim efficacy data from th