Epizyme Submits New Drug Application to the U.S. FDA for Tazemetostat for the Treatment of Patients with Epithelioid Sarcoma

Submission Follows Productive Pre-NDA Meeting and Marks On-time
Execution of First of Two NDA Submissions Planned for 2019

CAMBRIDGE, Mass.–(BUSINESS WIRE)–Epizyme,
Inc. (Nasdaq: EPZM), a late-stage biopharmaceutical company
developing novel epigenetic therapies, today announced that it has
submitted a New Drug Application (NDA) to the U.S. Food and Drug
Administration (FDA) for accelerated approval of tazemetostat for the
treatment of patients with metastatic or locally advanced epithelioid
sarcoma not eligible for curative surgery. Tazemetostat is an oral,
first-in-class, EZH2 inhibitor discovered by Epizyme and being developed
for a range of cancers and treatment settings.

This NDA submission follows a recently conducted pre-NDA meeting held
with FDA, in which the Agency considered the proposed clinical package
to be sufficient for inclusion with the NDA. The submission is based on
updated tazemetostat efficacy and safety data from 62 patients enrolled
in the epithelioid sarcoma cohort of the Phase 2 clinical trial, which
will be reported in an oral
presentation at the American Society of Clinical Oncology (ASCO)
2019 Annual Meeting. The company’s ongoing Phase 2 study cohort is the
largest prospective clinical trial in epithelioid sarcoma with any
approved or investigational anticancer treatment to date.

“Epithelioid sarcoma is a rare and aggressive cancer that affects people
in the prime of their lives, and we are very pleased to have recently
submitted the NDA for tazemetostat for the treatment of people with this
devastating cancer,” said Dr. Shefali Agarwal, chief medical officer of
Epizyme. “If approved, we believe tazemetostat has the potential to
change the care of patients with this disease. We are incredibly
grateful to the physicians and clinical teams who have helped advance
tazemetostat to this stage, and, most notably, to the patients and
caregivers who have participated in our clinical trials along the way.
We look forward to continuing to engage with the FDA as we work to bring
tazemetostat to patients and physicians in the U.S.”

To support a full approval of tazemetostat for epithelioid sarcoma,
Epizyme plans to conduct a global, randomized, controlled trial, that it
expects to begin in the second half of 2019. The final design of the
study is subject to alignment with FDA, and the company plans to
disclose details once it has reached alignment with FDA and the NDA
submission has been accepted for review. The FDA has a 60-day filing
review period to determine whether the NDA is complete and acceptable
for filing.

“At Epizyme, our mission is to deliver new treatments for patients with
cancer and other serious diseases, and today we stand one significant
step closer to achieving that,” said Robert Bazemore, president and
chief executive officer of Epizyme. “This submission is the culmination
of years of hard work by our entire team, and I wish to congratulate
them all on this accomplishment. Our epithelioid sarcoma program is
strategically valuable to Epizyme and helps streamline our planned NDA
submission in the fourth quarter, for patients with follicular lymphoma.
Over the coming months, we have multiple anticipated clinical data and
regulatory milestones, and we are well underway with commercialization
readiness activities to support the potential launch of tazemetostat and
our transition to a commercial-stage organization. 2019 is set to be a
transformational year for Epizyme, and I am enthusiastic for our
continued progress.”

About Epithelioid Sarcoma
Epithelioid sarcoma is an
ultra-rare soft tissue sarcoma characterized by a loss of the protein
INI1. Patients are most commonly diagnosed as young adults, between 20
and 40 years of age. Median overall survival from initial diagnosis is
30 months. Epithelioid sarcoma becomes more aggressive after recurrence
or metastases, with a typical survival of less than one year for
patients with metastatic disease.

About Epizyme, Inc.
Epizyme, Inc. is a late-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 also is
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 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; whether the NDA submission referred to
in this release will be accepted for review under the accelerated
approval process or at all, or approved on a timely basis or at all;
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, (617) 500-0615
Epizyme, Inc.
[email protected]

Investors:
Monique Allaire
THRUST Strategic
Communications
[email protected]