FDA approves Epizyme's Tazverik in sarcoma

The US regulator has approved Epizyme’s Tazverik (tazemetostat) for advanced sarcoma, providing a new option for a disease where there are high recurrence rates and toxicity issues with established treatments.

Tazverik, one of the stars of last year’s American Society of Clinical Oncology (ASCO) conference, is approved in adults and children aged 16 years and older with metastatic or locally advanced epithelioid sarcoma (ES), who are not eligible for complete resection.

The oral therapy was approved based on overall response rate and duration of response data from a phase 2 clinical trial.

Epizyme must produce confirmatory survival data from a larger trial, and has already started a global randomised trial assessing Tazverik in combination with doxorubicin, compared with doxorubicin plus placebo in untreated patients with ES.

Epizyme will conduct post-marketing activities, including clinical pharmacology evaluations to assess the effect of Tazverik on liver function and the effect of CYP3A inhibitors and inducers on the drug to further guide prescribers.

The company will also expand enrolment in Cohort 6 of its phase 2 study, which has enrolled 44 patients to date, for a total of at least 60 epithelioid sarcoma patients.

This expansion is intended to provide more patient experience for potential future inclusion in the label.

The FDA’s decision to approve came after a troubled clinical development after the FDA put trials on partial hold in 2018 because of a secondary lymphoma seen in a paediatric trial subject in a phase 1 trial.

The company eventually came up with a safety analysis that assuaged the FDA’s concerns, and approval looked almost certain after backing from an advisory panel of cancer experts before Christmas.

Epizyme is developing tazemetostat, a first-in-class EZH2 inhibitor, for several types of blood cancer and genetically defined solid tumours.

Epizyme holds global development and commercialisation rights to tazemetostat outside Japan. Eisai owns development and marketing rights to tazemetostat in Japan, and a right of first negotiation to rights in the rest of Asia.

Sales in ES are expected to be limited to around $100 million annually, but could be considerably boosted by approval in other indications.