Ipsen Voluntarily Withdraws Tazemetostat Following Updated Safety Findings from the SYMPHONY-1 Trial

Key Clinical Summary: 

• Tazemetostat was granted accelerated FDA approval in 2020 for relapsed/refractory follicular lymphoma and epithelioid sarcoma, contingent upon confirmatory trial results.
• Emerging data from SYMPHONY-1 identified increased adverse events of secondary hematologic malignancies, leading the Independent Data Monitoring Committee to conclude that the risk–benefit profile was unfavorable. 
• Ipsen has halted treatment, discontinued all active trials and expanded access programs, and initiated global withdrawal.
• Patients receiving tazemetostat will transition to standard-of-care therapy, and regulatory authorities are being engaged to complete withdrawal procedures. 
• The case underscores the importance of confirmatory trials in validating accelerated approvals.

Based on emerging safety data from the ongoing SYMPHONY-1 trial, Ipsen has voluntarily withdrawn tazemetostat (Tazverik^®) across all approved indications.

The decision follows a recommendation from the Independent Data Monitoring Committee, which determined that adverse events related to secondary hematologic malignancies in the SYMPHONY-1 study suggested that the risks of the tazemetostat-containing regimen may outweigh its potential benefits. 

SYMPHONY-1 is a global phase 1b/3 confirmatory trial evaluating tazemetostat in combination with lenalidomide and rituximab as second-line therapy among patients with relapsed/refractory (R/R) follicular lymphoma (FL). The study serves as the required confirmatory trial under the accelerated approval pathway for FL.

Based on these findings, Ipsen is withdrawing tazemetostat effective immediately in all markets, including for FL and epithelioid sarcoma. In addition, treatment with tazemetostat has been halted for all patients currently enrolled in SYMPHONY-1. Participants will transition to standard-of-care therapy with lenalidomide plus rituximab. The trial will remain open without further enrollment to allow continued long-term safety follow-up.

Ipsen is also discontinuing all active tazemetostat clinical trials and expanded access programs. The company is working with the US Food and Drug Administration (FDA) to execute the withdrawal process and provide necessary regulatory documentation.

Tazemetostat received US FDA accelerated approval in 2020 for adult patients with relapsed/refractory FL whose tumors are positive for an EZH2 mutation and who have received at least 2 prior systemic therapies, as well as for patients with relapsed or refractory FL with no satisfactory alternative treatment options. 

It also received accelerated approval in 2020 for adults and adolescents aged 16 years and older with metastatic or locally advanced epithelioid sarcoma not eligible for complete resection. These approvals were granted under the accelerated approval pathway based on overall response rate and duration of response, contingent upon verification of clinical benefit in confirmatory trials.

Company leadership emphasized that patient safety remains the priority and that support will be provided to investigators and clinical teams to ensure appropriate transition plans for affected patients.

Source: 

Ipsen. Ipsen voluntarily withdraws Tazverik® (tazemetostat) in follicular lymphoma and epithelioid sarcoma. Accessed March 11, 2026. https://www.ipsen.com/press-release/ipsen-voluntarily-withdraws-tazverik-tazemetostat-in-follicular-lymphoma-and-epithelioid-sarcoma-3251503/