The US Food and Drug Administration (FDA) has granted accelerated approval of the EZH2 inhibitor tazemetostat (Tazverik, Epizyme, Inc) for the treatment of relapsed or refractory follicular lymphoma in adult patients with tumors harboring an EZH2 mutation.
Eligible patients must have already received at least two prior systemic therapies and have tumors that are positive for an EZH2 mutation, as detected by an FDA-approved test. The FDA has also approved the cobas EZH2 Mutation Test (Roche Molecular Systems, Inc) as a companion diagnostic test for tazemetostat.
The new indication is also for adult patients with relapsed/refractory follicular lymphoma who have no other satisfactory alternative treatment options.
“In our view, there remains no clear standard of care in the relapsed and/or refractory [follicular lymphoma] population, as not all patients benefit from today’s available therapies,” said Shefali Agarwal, MD, chief medical officer of Epizyme, in a company press release. “Based on this label, physicians will have the ability to use their clinical discretion to prescribe tazemetostat for their relapsed or refractory patients regardless of EZH2 mutational status and without regard to a specific line of treatment where other options are not satisfactory.”
This accelerated approval is based on overall response rate and duration of response. Continued approval for these indications may be contingent upon verification and description of clinical benefit in confirmatory trials, the FDA notes.
Tazemetostat acts as an inhibitor of EZH2 methyltransferase. Earlier this year, the drug was approved for the treatment of metastatic or locally advanced epithelioid sarcoma in cases in which complete resection is not possible. It is the first drug with this mechanism of action and is the first to be indicated for epithelioid sarcoma.
Promising Efficacy in Phase 2 Trial
The new approval for use in follicular lymphoma was based on results from an open-label, single-arm, multicenter phase 2 clinical trial involving patients who had experienced disease progression after being treated with at least two prior systemic regimens. The cohort was divided into two treatment groups: One group consisted of 45 patients with EZH2-activating mutations, the other included 54 patients with wild-type EZH2.
All patients received tazemetostat at 800 mg administered orally twice a day. The primary efficacy outcome measures were overall response rate and duration of response, in accordance with International Working Group Non-Hodgkin Lymphoma criteria.
The median duration of follow-up was 22 months for patients with EZH2-activating mutations and 36 months for those with wild-type tumors.
Among the 45 patients with an EZH2-activating mutation, the median number of lines of prior systemic therapy was 2.0 (range, 1 – 11). In 49% of patients, disease was refractory to rituximab, and in 49%, it was refractory to the patient’s last therapy.
The overall response rate was 69%; 12% of patients achieved a complete response, and 57% achieved a partial response. The median duration of response was 10.9 months and ongoing.
In the cohort of 54 patients with wild-type EZH2, the median number previous therapies was 3.0 (range, 1 – 8); in 59% of patients, disease was refractory to rituximab, and in 41%, it was refractory to the patient’s last therapy.
The overall response rate to tazemetostat treatment was 34%; 4% of patients achieved a complete response, and 30% achieved a partial response. The median duration of response was 13 months.
Serious adverse reactions occurred in 30% of patients. The most common were fatigue, upper respiratory tract infection, musculoskeletal pain, nausea, and abdominal pain. Eight patients (8%) discontinued treatment during the trial because of adverse events. There were no reported deaths. No black box warnings have been published, and there are no contraindications.
“The durable responses observed with this drug are notable in the context of the safety profile and route of oral, at-home administration, and will offer an important new option for physicians as we care for patients with relapsed/refractory follicular lymphoma,” said John Leonard, MD, in a company press release. He is associate dean for clinical research and Richard T. Silver Distinguished Professor of Hematology and Medical Oncology, Meyer Cancer Center, Weill Cornell Medicine and New York–Presbyterian Hospital, New York, and an investigator in the ongoing phase 1b/3 confirmatory trial for tazemetostat.
“Follicular lymphoma remains an incurable disease, and even with the availability of new drugs in recent years, there have remained important unmet needs in the treatment of follicular lymphoma,” he commented.
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