The Food and Drug Administration (FDA) has granted accelerated approval to Tazverik™ (tazemetostat tablets; Epizyme) for the treatment of adults and pediatric patients aged 16 years and older with metastatic or locally advanced epithelioid sarcoma not eligible for complete resection.

Tazemetostat is an inhibitor of the methyltransferase, EZH2. The approval was based on data from a phase 2, open-label, single-arm study that included patients with histologically confirmed, metastatic or locally advanced epithelioid sarcoma; patients were required to have INI1 loss and an Eastern Cooperative Oncology Group performance status of 0-2. Tazemetostat was administered twice daily until disease progression or unacceptable toxicity. Co-primary efficacy end points included overall response rate and duration of response.

Results showed an overall response rate of 15% (95% CI, 7-26) in patients who received tazemetostat (N=62); 1.6% of patients had a complete response, while 13% had a partial response. In addition, 67% of patients had a response that was ≥6 months in duration (range in months: 3.7, 24.5+). 

With regard to safety, the most common adverse reactions included pain, fatigue, nausea, decreased appetite, vomiting, and constipation. Treatment with tazemetostat may increase the risk of developing secondary malignancies; across clinical trials of 668 adults, this occurred in 0.6% of patients. Additionally, the agent can cause fetal harm.

“Until today, there were no treatment options specifically for patients with epithelioid sarcoma,” said Richard Pazdur, MD, director of the FDA’s Oncology Center of Excellence and acting director of the Office of Oncologic Diseases in the FDA’s Center for Drug Evaluation and Research. “When we brought Tazverik’s application to the Oncologic Drugs Advisory Committee last month, the committee voted unanimously that the benefits of the drug outweighed the risks.”

Tazverik™ will be supplied as 200mg tablets. “Our commercial launch plans are underway, and we expect to make Tazverik™ available to [epithelioid sarcoma] patients and treating physicians across the US within 10 business days,” said Robert Bazemore, president and chief executive officer of Epizyme.

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The Company is also conducting a confirmatory trial that is assessing the combination of tazemetostat plus doxorubicin compared with doxorubicin and placebo as a frontline treatment for advanced epithelioid sarcoma.

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