Epizyme Presents Updated Data From Ongoing Phase I Study Of Tazemetostat Showing Objective, Durable Responses In Relapsed Or Refractory Non-Hodgkin Lymphoma

• Objective responses seen in nine of 16 (56 percent) response-evaluable patients with either relapsed or refractory Non-Hodgkin Lymphoma
• Four responders remain on study at data cutoff; durable and ongoing objective responses seen up to 19 months
• Recommended phase 2 dose supported by anti-tumor activity, safety, pharmacokinetic and pharmacodynamic data

ORLANDO, Fla.--(BUSINESS WIRE)--Epizyme, Inc. (NASDAQ:EPZM), a clinical stage biopharmaceutical company creating novel epigenetic therapeutics for cancer patients, reported updated results from the ongoing phase 1 trial of tazemetostat (EPZ-6438), a first-in-class oral EZH2 inhibitor. Data from this trial continue to show meaningful clinical activity with tazemetostat when used as an oral monotherapy in patients with either relapsed or refractory Non-Hodgkin Lymphoma (NHL). Nine of 16 response-evaluable patients with NHL have achieved an objective response, with the duration of responses lasting up to 19 months as of the data cutoff. The data were presented today by Vincent Ribrag, M.D., Institut Gustave Roussy, at the 57^th American Society of Hematology Annual Meeting (ASH).

“The phase 2 five-arm study, which is currently underway, will advance our understanding of the clinical utility of this agent in the different subsets of NHL. I believe tazemetostat has the potential to become an important new addition to the available treatment options for our patients.”

“In this ongoing phase 1 study, we continue to observe meaningful and durable clinical activity with tazemetostat in NHL patients,” said Dr. Ribrag. “The phase 2 five-arm study, which is currently underway, will advance our understanding of the clinical utility of this agent in the different subsets of NHL. I believe tazemetostat has the potential to become an important new addition to the available treatment options for our patients.”

Summary Results

As of the November 7, 2015 cutoff, the following clinical data were reported:

• Twenty-one patients with relapsed or refractory NHL were enrolled into the phase 1 study; 16 of the 21 patients were response-evaluable as defined by the study protocol.
• Nine of 16 (56 percent) response-evaluable NHL patients achieved an objective response.
• On an intent-to-treat basis, seven of 12 (58 percent) response-evaluable NHL patients treated at or above the recommended phase 2 dose of 800 mg twice daily (BID) achieved an objective response.
• Four patients remained on study at data cutoff with ongoing objective responses, including three patients who had been on drug for at least 18 months.
• 800 mg BID showed superior tolerability, equivalent anti-tumor activity and equivalent pharmacodynamic activity as compared to the 1600 mg BID dose.
• The majority of adverse events were grade 1 or grade 2 within the 55 patients with NHL and solid tumors who were evaluable for safety. The most common adverse events, regardless of attribution, were asthenia, anorexia, thrombocytopenia, nausea, constipation, diarrhea, and vomiting. Four grade 3 or greater treatment-related adverse events have been observed including one each of: grade 3 hypertension, grade 3 liver function test elevation, grade 4 thrombocytopenia, and grade 4 neutropenia.

Study Design

This open-label, multi-center, phase 1 study is investigating tazemetostat as monotherapy in patients with relapsed or refractory B-cell Non-Hodgkin Lymphoma or advanced solid tumors. The study objectives include identification of the recommended phase 2 dose or maximum tolerated dose, safety, tolerability, pharmacokinetics and preliminary evaluation of anti-tumor activity. Five cohorts were studied in the dose escalation phase: 100 mg, 200 mg, 400 mg, 800 mg and 1600 mg; and two cohorts, 800 mg and 1600 mg, were evaluated in the dose expansion phase. All doses were given twice daily. In addition, the study included two clinical pharmacology sub-studies: one for food effect and the other for drug-drug interaction. In the food effect sub-study, patients received a single 200 mg dose of tazemetostat either fasted or immediately after a high-fat breakfast in a randomized crossover fashion with seven days between doses. Patients received 400 mg BID after completing the seven-day crossover component of the study. Five of the 21 NHL patients were in the food effect sub-study.

Expanded Tazemetostat Registration-Supporting Phase 2 Program in NHL

Epizyme is conducting an international, multi-center, phase 2 study comprised of five independent arms. This study, which began enrolling patients in the second half of 2015, will assess the safety and efficacy of 800 mg BID of tazemetostat in patients with relapsed or refractory NHL, stratified by cell of origin and EZH2 mutation status. Epizyme plans to present interim results from the phase 2 study at a medical conference in mid-2016.

About EZH2 in Cancer

EZH2 is a histone methyltransferase (HMT) that is increasingly understood to play a potentially oncogenic role in a number of cancers. These include Non-Hodgkin Lymphoma, INI1-deficient cancers such as malignant rhabdoid tumors, epithelioid sarcomas and synovial sarcoma; and a range of other solid tumors.

About Tazemetostat

Epizyme is developing tazemetostat for the treatment of non-Hodgkin lymphoma patients and patients with INI1-deficient solid tumors. Tazemetostat is a first-in-class small molecule inhibitor of EZH2 created by Epizyme using its proprietary product platform. In many human cancers, aberrant EZH2 enzyme activity results in misregulation of genes that control cell proliferation resulting in the rapid and unconstrained growth of tumor cells. Tazemetostat is the WHO International Non-Proprietary Name (INN) for EPZ-6438.

Additional information about this program, including clinical trial information, may be found here: https://clinicaltrials.gov/ct2/show/NCT01897571

About Epizyme, Inc.

Epizyme, Inc. is a clinical-stage biopharmaceutical company creating novel epigenetic therapeutics for cancer patients. Epizyme has built a proprietary product platform that the Company uses to create small molecule inhibitors of chromatin modifying proteins (CMPs), such as histone methyltransferases or HMTs. CMPs are part of the system of gene regulation, referred to as epigenetics, that controls gene expression. Genetic alterations can result in changes to the activity of CMPs, making them oncogenic (cancer-causing). By focusing on the genetic drivers of cancers, Epizyme’s targeted science seeks to match the right medicines with the right patients.

For more information, visit www.epizyme.com and connect with us on Twitter at @EpizymeRx.

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Any statements in this press release about future expectations, plans and prospects for Epizyme, Inc. and other statements containing the words “anticipate,” “believe,” “estimate,” “expect,” “intend,” “may,” “plan,” “predict,” “project,” “target,” “potential,” “will,” “would,” “could,” “should,” “continue,” and similar expressions, constitute forward-looking statements within the meaning of The Private Securities Litigation Reform Act of 1995. Actual results may differ materially from those indicated by such forward-looking statements as a result of various important factors, including: uncertainties inherent in the initiation of future clinical studies or expansion of ongoing clinical studies; availability and timing of data from ongoing clinical studies; whether interim results from a clinical trial such as the results referred to in this release will be predictive of the final results of the trial or the results of future trials; expectations for regulatory approvals to conduct trials or to market products; development progress of the Company’s companion diagnostics, availability of funding sufficient for the Company’s foreseeable and unforeseeable operating expenses and capital expenditure requirements; other matters that could affect the availability or commercial potential of the Company’s therapeutic candidates or companion diagnostics; and other factors discussed in the “Risk Factors” section of the company’s Form 10-Q filed with the SEC on November 9, 2015, and in our other filings from time to time with the SEC. In addition, the forward-looking statements included in this press release represent the Company’s views as of the date hereof. The Company anticipates that subsequent events and developments will cause the Company’s views to change. However, while the Company may elect to update these forward-looking statements at some point in the future, the Company specifically disclaims any obligation to do so. These forward-looking statements should not be relied upon as representing the Company’s views as of any date subsequent to the date hereof.