The FDA granted accelerated approval to tazemetostat for patients aged 16 years or older with metastatic or locally advanced epithelioid sarcoma ineligible for complete resection.
Tazemetostat (Tazverik, Epizyme) is an oral small-molecule inhibitor that blocks the activity of EZH2 methyltransferase, which is believed to prohibit the growth of cancer cells. The agent previously received FDA orphan drug designation, granted to manufacturers of treatments for rare diseases or disorders that affect fewer than 200,000 people in the United States.
“Epithelioid sarcoma accounts for less than 1% of all soft tissue sarcomas,” 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, said in a press release. “Until today, there were no treatment options specifically for patients with epithelioid sarcoma.”
The FDA based its approval on results of the EZH-202 trial, which included 62 patients with metastatic or locally advanced epithelioid sarcoma who received 800 mg tazemetostat twice daily until disease progression or unacceptable level toxicity. Researchers reported an overall response rate of 15%, including a 1.6% complete response and 13% partial response rate. Six (67%) of the nine patients who responded to tazemetostat had a response that lasted 6 months or longer.
Last month, the FDA’s Oncologic Drugs Advisory Committee voted 11-0 in favor of tazemetostat approval despite the low response rate, as Healio previously reported. The committee concluded the 15% ORR represented a durable benefit for a group of patients who had few other treatment options.
“A response rate as shown in this trial of 11% to 15% is considered clinically meaningful in my opinion,” Richard Francis Riedel, MD, associate professor of medicine at Duke University School of Medicine and member of Duke Cancer Institute, said during the committee discussion.
The most common adverse effects associated with tazemetostat included pain, fatigue, nausea, decreased appetite, vomiting and constipation, in addition to increased risk for developing secondary malignancies.