FDA Votes Unanimously In Favor Of Epizyme's Tazemetostat

Epizyme Inc EPZM shares were halted ahead of an Adcom meeting scheduled for Wednesday.

FDA's Oncologic Drugs Advisory Committee will discuss Epizyme's NDA for tazemetostat tablets, an EZH2 inhibitor, for the treatment of patients with metastatic or locally advanced epithelioid sarcoma not eligible for curative surgery.

A Rare Disease With Less Effective Treatment

Epithelioid sarcoma is a rare and serious soft tissue sarcoma, or STS, with a high rate of local recurrence and distant metastasis. Diagnosis of epithelioid sarcoma presents a challenge, as it presents symptoms similarly to other benign or malignant neoplasms, and therefore are not diagnosed until it has progressed to late stage.

Most treatment options for epithelioid sarcoma are chemo agents, which produce low response rates and substantial toxicities.

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Staffers Question Benefit-Risk Profile

The briefing document prepared by FDA staffers ahead of the meeting and made public Monday showed staffers acknowledge the need for new therapies with a favorable risk-profile.

FDA staffers, however, are "concerned that there may be insufficient evidence at this time to conclude that tazemetostat confers benefit in patients with epithelioid sarcoma."

The objective response rate, or ORR, for tazemetostat in epithelioid sarcoma, according to the pooled data from Cohorts 5 and 6, was 13%, with a 95% confidence interval, the FDA said. Therefore, the agency believes true estimated response rate could be as low as 4% to 7%, which is inferior to 24% ORR for doxorubicin, which was approved for STS in 1974.

Street Less Optimistic

Tazemetostat is Epizyme's lead drug being evaluated in multiple indications. The candidate is studied in a mid-stage trial as a monotherapy for relapsed/refractory follicular lymphoma among other indications.

Epithelioid sarcoma is a relatively small indication, with a market opportunity at less than $50 million compared to the $500 million opportunity presented in follicular lymphoma, Fierce Biotech quoted Jefferies analyst Michael Yee as saying.

On Wednesday afternoon, the FDA advisory committee voted unanimously in favor of tazemetostat for the treatment of patients with epithelioid sarcoma.

The stock closed up 10.5% at $20.10 per share.