FDA grants accelerated approval for Epizyme's Tazverik in epithelioid sarcoma

Epizyme announced Thursday that its regulatory filing for Tazverik (tazemetostat) received accelerated FDA approval for the treatment of adults and paediatric patients aged 16 years and older with metastatic or locally advanced epithelioid sarcoma who are not eligible for complete resection. CEO Robert Bazemore noted that Tazverik is the first FDA-approved EZH2 inhibitor, as well as the first treatment specifically indicated for epithelioid sarcoma. "Our commercial launch plans are under way, and we expect to make Tazverik available to patients...across the US within 10 business days," he added, with the company pricing the drug at $15,500 per month.

An FDA advisory panel voted unanimously last month to back the drug, which is also known as EPZ-6438, with approval based on data from a 62-patient cohort of the Phase II EZH-202 trial. Participants received Tazverik orally twice daily until disease progression or unacceptable toxicity, with the major efficacy outcome measures being overall response rate (ORR) and duration of response.

According to Epizyme, the ORR was 15% with 1.6% of patients achieving a complete response and 13% achieving a partial response. Among responders in the trial, 67% had a duration of response that lasted six months or more. Meanwhile, serious adverse reactions occurred in 37% of patients receiving Tazverik. The most frequent side effects requiring dosage interruptions were haemorrhage, as well as increased alanine aminotransferase and aspartate aminotransferase levels, while one patient permanently discontinued the drug after experiencing an "altered mood" adverse reaction.

Epizyme noted that a randomised confirmatory trial evaluating the combination of Tazverik plus doxorubicin against doxorubicin plus placebo as a front-line treatment for epithelioid sarcoma is currently underway. The company also plans to conduct certain post-marketing evaluations to assess the effect of Tazvrik on liver function and the effect of CYP3A inhibitors and inducers on the drug. Further, Epizyme said it will expand enrollment in another cohort of its Phase II study, which has enrolled 44 patients to date, for a total of at least 60 epithelioid sarcoma patients, "to provide more patient experience for potential future inclusion in the label."

Epizyme recently applied to have Tazverik approved in the US for follicular lymphoma, and the drug has also been fast-tracked by the FDA as a potential treatment for patients with diffuse large B-cell lymphoma with EZH2 activating mutations.

Epizyme holds global development and commercialisation rights to Tazverik outside of Japan, while Eisai owns rights to the drug in Japan, and also has the option of first negotiation to rights in the rest of Asia.

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