Epizyme Shares Drop After Partial Clinical Hold Placed On Lead Cancer Drug

Shares of clinical-stage biotech company Epizyme Inc EPZM, which specializes in novel epigenetic therapies, took a tumble after a negative event.

In pre-market trading Tuesday, the shares were down 14.38 percent to $13.10, the lowest level since Jan. 9, when they closed at $12.50.

What Happened

Epizyme announced Monday after the close that the FDA issued a partial clinical hold on the U.S. enrollment of new patients in tazemetostat clinical trials.

Tazemetostat is an orally administered small molecule EZH2 inhibitor that's being tested for multiple types of hematological malignancies and genetically defined solid tumors.

The hold comes after a pediatric patient enrolled in the Phase 1 pediatric trial developed a secondary lymphoma. 

"Doses explored in this study are higher than those in the company's Phase 2 adult studies, an approach not uncommon to drug development in aggressive, difficult-to-treat pediatric cancers," the company said in the release.

Tazemetostat is also currently being tested as a single-agent therapy in Phase 2 clinical trials in:

Patients with relapsed or refractory non-Hodgkin lymphoma.

Adult patients with certain genetically defined solid tumors, including INI1-negative tumors and synovial sarcoma.

Patients with mesothelioma characterized by BAP loss of function.

Why It's Important

Taxemetostat demonstrated impressive efficacy in blood cancers and solid tumors with minimal toxicities, and Morgan Stanley analyst Andrew Berens said in a January note that the pipeline candidate is a compelling proposition that allows integration into existing regimens both as a treatment agent and maintenance drug.

The NDA for tazemetostat in the treatment of epithelioid sarcoma in INI1-negative patients is likely to be submitted by the fourth quarter , H.C. Wainwright said in a recent note. 

Although the partial clinical hold pertains to the pediatric study, it could stir anxiety concerning the timeline for other indications as well.

What's Next

The partial clinical hold will affect new enrolment of patients with genetically-defined solid tumors and hematologic malignancies.

The company said patients who are already enrolled and have not experienced disease progression can continue to receive tazemetostat.

Epizyme said it has embarked on developing the modifications needed to address the partial clinical hold, as it will need to confirm alignment with the regulatory agency in order to resume U.S. enrollment.

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