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Epizyme Presents Encouraging Phase 2 Data of Tazemetostat for Malignant Mesothelioma at ASCO

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  • Disease Control Rate of 51 Percent Achieved at 12 Weeks
  • Represents the First Reported Clinical Data of an EZH2 Inhibitor in Patients with Relapsed/Refractory Malignant Mesothelioma

CAMBRIDGE, Mass., June 03, 2018 (GLOBE NEWSWIRE) -- Epizyme, Inc. (NASDAQ:EPZM), a clinical-stage company developing novel epigenetic therapies, today announced the first detailed results from the Phase 2 study of its lead candidate tazemetostat, a potent, selective, orally available EZH2 inhibitor, in relapsed/refractory malignant mesothelioma patients with BRCA1-associated protein 1 (BAP1) loss-of-function. The data will be presented during a poster and subsequent discussion session at the American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago.

The primary endpoint was met with 51 percent of patients (31/61) having achieved disease control at 12 weeks, exceeding the pre-specified disease control rate (DCR) threshold of ≥35 percent. DCR is defined as complete response, partial response (PR) or stable disease. As of January 16, 2018, 16 patients (26%) had maintained disease control for ≥24 weeks since starting treatment with tazemetostat, two of whom achieved PR. Patients enrolled in the study were heavily pretreated, with a median of two prior lines of therapy.

"We are always searching for promising new treatments for patients with mesothelioma, particularly for those with relapsed or refractory disease," said Marjorie G. Zauderer, M.D., medical oncologist and Co-Director of the Mesothelioma Program at Memorial Sloan Kettering Cancer Center. "Today's findings show that tazemetostat monotherapy substantially delayed disease progression without significant toxicities, which is clinically meaningful. This is encouraging for the patients and families impacted by mesothelioma, and for the oncologists who treat them."

The Phase 2, multicenter, open-label study was designed to evaluate 800 mg of tazemetostat monotherapy administered orally twice daily in adult patients with measurable relapsed/refractory malignant mesothelioma. The trial enrolled 74 patients and was conducted in two parts: the first part enrolled patients regardless of BAP1 status (n=13) to evaluate the safety and pharmacokinetics (PK) of tazemetostat. The second part enrolled patients with BAP1 loss-of-function (n=61) to determine DCR. Secondary endpoints included overall response rate, progression-free survival, overall survival, safety, population PK and response biomarkers.

Consistent with findings from adult studies across the tazemetostat clinical development program, tazemetostat was generally well tolerated. No patients discontinued due to treatment-emergent adverse effects (TEAEs); five patients had dose reductions due to TEAEs. The five most frequently reported TEAEs (all grades) were fatigue (32%), decreased appetite (28%), dyspnea (28%), nausea (27%), and cancer pain (26%), regardless of relationship to study drug.

"We'd like to thank the patients who participate in clinical trials and the caregivers who support them, in an effort to help advance the treatment of mesothelioma," said Robert Bazemore, president and chief executive officer of Epizyme. "We are encouraged by these positive results in this difficult-to-treat cancer, making it a compelling candidate for exploration as a combination therapy."

About Mesothelioma
Mesothelioma is a rare, aggressive form of cancer that develops in the soft tissue that surrounds the lung, known as the pleura, in addition to the abdomen or heart. The life expectancy for mesothelioma patients is poor, with most patients living less than one year. Across the U.S., EU5 and Japan, an estimated 12,400 new cases of mesothelioma are diagnosed each year. BAP1 loss-of-function is present in approximately 50 percent of patients.

About the Tazemetostat Clinical Trial Program
Tazemetostat, a first-in-class EZH2 inhibitor, is currently being studied as a monotherapy in ongoing Phase 1 and 2 programs in certain molecularly defined solid tumors, including epithelioid sarcoma (ES) and other INI1-negative tumors; both follicular lymphoma (FL) and diffuse large B-cell lymphoma (DLBCL) forms of non-Hodgkin lymphoma (NHL); mesothelioma and combination studies in DLBCL.

About Epizyme, Inc.
Epizyme, Inc. is a clinical-stage biopharmaceutical company committed to rewriting treatment for cancer and other serious diseases through novel epigenetic medicines. Epizyme is broadly developing its lead product candidate, tazemetostat, a first-in-class EZH2 inhibitor, with studies underway in both solid tumors and hematological malignancies, as a monotherapy and combination therapy in relapsed and front-line disease. The company is also developing a novel G9a program with its next development candidate, EZM8266, which is targeting sickle cell disease. By focusing on the genetic drivers of disease, Epizyme's science seeks to match targeted medicines with the patients who need them. For more information, visit www.epizyme.com.

Cautionary Note on Forward-Looking Statements
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 relating to the Company's ability to resume enrollment in its tazemetostat trials and the timing of such resumption, and the impact of the safety finding on enrollment of patients in ongoing and future trials of tazemetostat following the lifting of the partial clinical hold and the resumption of enrollment; uncertainties inherent in the initiation of future clinical studies and in the availability and timing of data from ongoing clinical studies; whether interim results from a clinical trial will be predictive of the final results of the trial; whether results from preclinical studies or earlier clinical studies will be predictive of the results of future trials; whether results from clinical studies will warrant meetings with regulatory authorities, submissions for regulatory approval or review by governmental authorities under the accelerated approval process; whether Fast Track Designation and Orphan Drug Designations will provide the benefits for which tazemetostat is eligible; expectations for regulatory approvals to conduct trials or to market products; whether the company's cash resources will be sufficient to fund 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; and other factors discussed in the "Risk Factors" section of the company's most recent Form 10-Q filed with the SEC and in the company's 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 and should not be relied upon as representing the company's views as of any date subsequent to 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.

Contacts:

Media:
Erin Graves, Epizyme, Inc.
media@epizyme.com
(617) 500-0615

Investors:
Jason Fredette, Epizyme, Inc.
ir@epizyme.com
(617) 500-0623

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