Epizyme (EPZM) Announces FDA Acceptance of IND for Tazemetostat

Epizyme, Inc. (NASDAQ: EPZM), a clinical stage biopharmaceutical company creating novel epigenetic therapies for patients with cancer, today announced the U.S. Food and Drug Administration (FDA) has accepted the company’s investigational new drug (IND) application for tazemetostat for the treatment of adults and pediatric patients with INI1-negative tumors or synovial sarcoma. In the second half of 2015, Epizyme plans to initiate a multi-center phase 2 study in adults and a multi-center phase 1 study in children to evaluate tazemetostat in patients with relapsed or refractory INI1-negative tumors or synovial sarcoma.

“Patients with INI1-negative tumors have a life-threatening disease and few treatment options. Our development approach reflects Epizyme’s strategy for aggressively advancing tazemetostat for indications with high unmet need,” said Peter Ho, M.D., Ph.D., Chief Development Officer. “These clinical studies and our IND enable the expansion of our clinical development program, as we aim to establish tazemetostat’s benefit globally in multiple therapeutic areas where it has shown promise in early research.”

“We believe the treatment of INI1-negative tumors offers an opportunity for us to establish a strong clinical profile for tazemetostat in multiple patient populations and reinforces Epizyme’s leadership position in the field of targeted epigenetic therapeutics,” added Robert Gould, Ph.D., President and Chief Executive Officer. “These new registration-supporting studies in INI1-negative tumors and synovial sarcoma will complement our ongoing 5-arm phase 2 study of tazemetostat in non-Hodgkin lymphoma, which is actively enrolling patients.”

INI1 is a critical component of the SWI/SNF regulatory complex, a chromatin remodeler that acts in opposition to EZH2. INI1-negative tumors have altered SWI/SNF function, resulting in aberrant and oncogenic EZH2 activity. This activity can be targeted by small molecule inhibitors of EZH2 such as tazemetostat. INI1-negative tumors are generally aggressive and are poorly served by current treatments. For example, current treatment of MRT, a well-studied INI1-negative tumor, consists of surgery, chemotherapy and radiation therapy, which are associated with limited efficacy and significant treatment-related morbidity. The annual incidence of patients with INI1–negative tumors and synovial sarcoma in major markets, including the U.S., E.U. and Japan, is approximately 2,400.1

The adult phase 2 multicenter study will enroll up to 90 patients in three cohorts. The first cohort will be comprised of patients with malignant rhabdoid tumor (MRT), rhabdoid tumor of the kidney (RTK) and atypical teratoid / rhabdoid tumor (ATRT). The second cohort will be comprised of patients with other INI1-negative tumors including epithelial sarcoma, epithelioid malignant peripheral nerve sheath tumor, extraskeletal myxoid chondrosarcoma, myoepithelial carcinoma, and renal medullary carcinoma. The third cohort will be comprised of patients with synovial sarcoma. Dosing in all three cohorts will be at the recommended phase 2 dose of 800 mg twice per day (BID) with a tablet formulation, which Epizyme is also using in its ongoing phase 2 trial in non-Hodgkin lymphoma. The primary endpoint is overall response rate (ORR) for patients with INI1-negative tumors and progression-free survival (PFS) for patients with synovial sarcoma. Secondary endpoints include duration of response, overall survival (OS), PFS for patients with INI1-negative tumors, safety and pharmacokinetics (PK).

The pediatric phase 1 multicenter study will enroll approximately 40 patients in a dose escalation design, followed by dose expansion, with an oral suspension of tazemetostat. The study will enroll subjects with INI1-negative tumors or synovial sarcoma. INI1-negative tumors include MRT, ATRT, RTK, and other INI1-negative tumors as previously described. The primary endpoint of study is safety with the objective of establishing the recommended phase 2 dose in pediatric patients. Secondary endpoints include PK, ORR, duration of response, PFS and OS.

Epizyme will present a clinical update for the phase 1 portion of the ongoing phase 1/2 trial of tazemetostat at ESMO’s European Cancer Conference on September 26, 2015. This update will include safety data from the entire cohort and efficacy data from patients with solid tumors including INI1-negative tumors.

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