Epizyme puts enrolment of patients in tazemetostat trials on hold

The US Food and Drug Administration (FDA) has issued a partial clinical hold on the enrolment of new patients in Epizyme’s ongoing Phase I and II trials of tazemetostat to treat genetically defined solid tumours and hematologic malignancies.

The clinical hold is based on a safety report submitted by Epizyme to the FDA, detailing the condition of a paediatric patient with advanced poorly differentiated chordoma who developed a secondary T-cell lymphoma in the Phase I trial.

During the submission of the report, the patient had been on study for around 15 months and achieved a confirmed partial response.

Following the development of secondary malignancy, the patient has stopped taking tazemetostat and is currently being treated for T-cell lymphoma.

According to Epizyme, doses used in the Phase I trial are higher than the doses explored in the Phase II adult study, which is a very common approach used in the development of difficult-to-treat paediatric cancer drugs.

The company also noted that this is the only incident where a patient treated with tazemetostat developed secondary lymphoma under its clinical trial programme that has so far treated over 750 patients.

Epizyme president and CEO Robert Bazemore said: “Patient safety is of the utmost importance to Epizyme.

“We are working expeditiously with clinical trial investigators and regulatory authorities to initiate the appropriate steps to resume enrolment.

“Epizyme, along with our global investigator community, has been very encouraged by the clinical responses and tolerability of tazemetostat observed in paediatric and adult patients with hematological malignancies and solid tumours enrolled in our trials.”

Under the Phase I and II trials of tazemetostat, Epizyme aims to develop the EZH2 inhibitor as a monotherapy for the treatment of certain molecularly defined solid tumours, including epithelioid sarcoma and other INI1-negative tumours.