Epizyme files tazemetostat, seeking first okay in rare cancer

Epizyme has filed for accelerated FDA approval of tazemetostat for advanced epithelioid sarcoma (ES), a rare form of cancer with no approved drugs in the US.

The Massachusetts biotech is seeking a green light for the first-in-class EZH2 inhibitor in patients with metastatic or locally advanced ES not suitable for surgery, which can be curative in this rare type of slow-growing tumour if caught early enough.

The cancer typically starts as a single painless lump, but can quickly spread to form multiple growths and be quite aggressive by the time a patient seeks medical advice. Treatment options at the moment are surgery, radiotherapy and chemotherapy, and if approved tazemetostat would be the first targeted therapy for ES.

“We believe that tazemetostat could dramatically change the care of people with ES who have limited treatment options, which are also associated with challenging side effects,” said the biotech’s CEO Rob Bazemore earlier this year.

Analysts at Jefferies have suggested that the accelerated application based on a phase 2 trial in 62 patients – due to be reported at ASCO on 3 June – looks “approvable” given that tazemetostat’s objective response rates and duration of response seem to be better than data for other drugs used to treat sarcomas.

According to the ASCO abstract, the drug achieved an ORR of 15%, with an average duration of response of more than 12 months, and what looks like a benign side-effect profile. If the FDA concurs with that view, tazemetostat could be on the market next year, and Epizyme has committed to carrying out a global, confirmatory phase 3 trial in the latter half of the year.

ES is the first of two submissions planned for tazemetostat this year as Epizyme attempts to position its orally-active drug in a range of solid tumours and blood cancers.

Next up is a filing in the fourth quarter for third-line or later treatment of follicular lymphoma (FL), a cancer that is a much bigger opportunity than ES, particularly if Epizyme can follow through on its plan to move tazemetostat into earlier lines of treatment.

While ES is a relatively small indication – representing around $100 million in potential annual sales according to some analysts -  last year Morgan Stanley suggested that approval in additional cancers could propel tazemetostat towards blockbuster sales levels.

Epizyme has trials planned for the drug in combination with Roche’s Rituxan (rituximab) for the treatment of patients with relapsed refractory FL, as well as part of a triple therapy with Rituxan and Celgene’s Revlimid (lenalidomide) – a regimen known as R2 that has just been approved as a second-line treatment for FL and other forms of indolent non-Hodgkin’s lymphoma (NHL).