The U.S. Food and Drug Administration has lifted the partial clinical hold on trials of tazemetostat, an EZH2 inhibitor being developed to treat solid tumors and lymphomas, according to a press release from the drug’s developer Epizyme.
The patient had been on study for approximately 15 months and had achieved a confirmed partial response. The patient has since discontinued tazemetostat and responded to treatment for T-LBL.
“This remains the only case of T-LBL we’ve seen in more than 750 patients treated with tazemetostat,” Robert Bazemore, president and chief executive officer of Epizyme, said in a webcast on Sept. 24.
Epizyme assessed the risk of secondary malignancies, including T-LBL, as well as the overall risks and benefits of tazemetostat treatment, conducting a review of the published literature and an examination of efficacy and safety data across all of its tazemetostat trials. A panel of external scientific and medical experts who reviewed the findings concluded that T-LBL risks appear to be confined to pediatric patients who received higher doses of the drug. The phase 1 pediatric study in which the patient developed T-LBL included higher doses of tazemetostat than those used in the phase 2 adult studies.
“The team at Epizyme has worked diligently in collaboration with external experts and the FDA over the past several months,” Mr. Bazemore said.
The company is not making any substantial changes to trial designs or the patient populations involved in tazemetostat trials. However, Epizyme is modifying dosing in the pediatric studies, improving patient monitoring, and making changes to exclusion criteria to reduce the potential risk of T-LBL and other secondary malignancies. Mr. Bazemore said Epizyme hopes to submit a New Drug Application for tazemetostat in the treatment of epithelioid sarcoma.
Tazemetostat is under investigation as monotherapy in phase 2 trials of follicular lymphoma and solid-tumor malignancies. The drug is also being studied as part of combination therapy for non–small cell lung cancer and diffuse large B-cell lymphoma (DLBCL).
In August, Epizyme announced its decision to stop developing tazemetostat for use as monotherapy or in combination with prednisolone for patients with DLBCL. However, tazemetostat is still under investigation as a potential treatment for DLBCL as part of other combination regimens.
Epizyme is now working to resolve partial clinical holds placed on tazemetostat in France and Germany in order to resume trial enrollment in those countries.