FDA Approves First Treatment Specifically for Epithelioid Sarcoma

The U.S. Food and Drug Administration approved Tazverik™ (tazemetostat) for the treatment of adults and pediatric patients aged 16 years and older with metastatic or locally epithelioid sarcoma who are ineligible for complete resection. This is the first treatment specifically approved for the rare soft-tissue sarcoma that often occurs in young adults.

The decision was based on results of an open-label clinical trial that included 62 patients with metastatic or locally advanced epithelioid sarcoma. Patients received tazemetostat 800 mg twice daily until disease progression or unacceptable toxicity. Tumor response was assessed every eight weeks during the trial.

Responses observed with tazemetostat

The overall response rate was 15% (n=9), including a complete response in 1.6% of patients and a partial response in 13% of patients. Among responders, six patients (67%) had a response that lasted six months or longer.

The most common adverse events associated with tazemetostat were pain, fatigue, nausea, decreased appetite, vomiting, and constipation. Patients receiving tazemetostat are at an increased risk of developing secondary malignancies, including T-cell lymphocytic lymphoma, myelodysplastic syndromes, and acute myeloid leukemia.

Patients who are breastfeeding or pregnant should not take tazemetostat.

Continued approval of tazemetostat is contingent upon verification and description of clinical benefit in a confirmatory trial. A global, randomized, controlled confirmatory trial is now underway to assess the combination of tazemetostat plus doxorubicin compared with doxorubicin plus placebo as a frontline treatment for epithelial sarcoma.