The US Food and Drug Administration (FDA) has placed a partial hold on clinical trials of tazemetostat, an EZH2 inhibitor being developed to treat solid tumors and lymphomas.
The hold has halted enrollment in US-based trials of tazemetostat, but study subjects who have not experienced disease progression may continue to receive the drug.
The hold is due to an adverse event observed in a pediatric patient on a phase 1 study of tazemetostat.
The patient, who had advanced poorly differentiated chordoma, developed a secondary T-cell lymphoma while taking tazemetostat.
The patient had been on study for approximately 15 months and had achieved a confirmed partial response. Now, the patient has discontinued tazemetostat and is being treated for T-cell lymphoma.
More than 750 patients have been treated with tazemetostat to date, and this is the only case of secondary lymphoma that has been observed, according to Epizyme, Inc., the company developing tazemetostat.
The company also noted that doses of tazemetostat explored in its phase 1 pediatric study are higher than those used in the phase 2 adult studies.
Epizyme has begun taking steps to address the hold on tazemetostat trials—updating the informed consent, investigator’s brochure, and study protocols.
The company will need to confirm alignment with the FDA in order to resume US enrollment.
“We are working expeditiously with clinical trial investigators and regulatory authorities to initiate the appropriate steps to resume enrollment,” said Robert Bazemore, president and chief executive officer of Epizyme.
“Epizyme, along with our global investigator community, has been very encouraged by the clinical responses and tolerability of tazemetostat observed in pediatric and adult patients with hematological malignancies and solid tumors enrolled in our trials. We remain encouraged by the potential of tazemetostat to address the unmet needs of many patients living with cancer.”