FDA Approves Tazverik (Tazemetostat) for Epithelioid Sarcoma

The US Food and Drug Administration (FDA) has approved Tazverik (tazemetostat) to treat adults and children 16 and older with epithelioid sarcoma, a rare cancer which accounts for less than 1% of all soft tissue sarcomas. This drug is for patients whose cancer has spread either locally or to other parts of the body and can’t be removed completely with surgery. Tazverik is only the second targeted therapy approved for a soft tissue sarcoma and the first treatment option specifically for epithelioid sarcoma.

Tazverik works by blocking activity of the EZH2 enzyme, which may help keep the cancer cells from growing. The FDA based its approval on a clinical trial of 62 people with epithelioid sarcoma that had spread. The trial measured overall response rate, which is how many patients’ tumors shrank either partially or completely by a certain amount. The overall response rate was 15%, with 1.6% of patients (1 patient) having a complete response and 13% (8 patients) having a partial response. Of the 9 patients who had a response, 6 had a response that lasted 6 months or longer.

The FDA granted Tazverik accelerated approval, which allows a faster approval for drugs for serious conditions. It may require more clinical trials to show whether the drug is beneficial. Tazverik also received orphan drug designation, which provides incentives to develop drugs for rare diseases.

Tazverik comes in pill form and is taken twice a day. The most common side effects were pain, fatigue, nausea, decreased appetite, vomiting and constipation. Tazverik also increased the risk of developing T-cell lymphoblastic lymphoma (a type of blood cancer), myelodysplastic syndrome (a disorder resulting from poorly formed or dysfunctional blood cells) and acute myeloid leukemia (a cancer of the blood and bone marrow).

Women and men of reproductive age should use birth control while taking Tazverik. Women should also use birth control for 6 months after the final dose and men for 3 months. Women who are pregnant or breastfeeding should not take Tazverik because it may harm a developing fetus or newborn baby.

Tazverik is marketed by Epizyme Inc.