Epizyme Inc.'s experimental drug tazemetostat reduced the extent of a type of blood cancer in patients in a mid-stage trial.
The ongoing phase 2 study evaluated tazemetostat as a stand-alone therapy for patients with follicular lymphoma that had returned or did not respond to initial treatment. The patients were divided across two groups based on the status of the mutation of a gene called EZH2, which can help cancerous cells divide and multiply.
Follicular lymphoma is a type of cancer that develops when the body makes abnormal versions of a type of white blood cell called B lymphocytes, which help protect the body against bacteria or viruses by making proteins called antibodies.
Interim results from the trial showed that 71% of 28 patients with the EZH2 gene mutation saw a reduction of the extent of the disease in their system after treatment with tazemetostat, an EZH2 inhibitor, with 11% of patients seeing no detectable levels of the cancer in their system — known as a complete response — and 61% of patients seeing their disease reduced but not completely going away, a result known as a partial response.
In addition, 33% of 54 patients who had a wild-type version of the EZH2 gene saw a decrease in their cancer, with 6% of patients experiencing a complete response and 28% of patients achieving a partial response.
Patients with the EZH2 gene mutation lived for a median of more than 48.6 weeks without their disease worsening, while those with the wild-type version survived for a median of 29.9 weeks without their cancer progressing. Disease progression was seen after a median of more than 32.3 weeks in patients with the EZH2 gene mutation and after more than 76 weeks in those with the wild-type EZH2 gene.
Tazemetostat was well tolerated in the study and only 6% of patients discontinued treatment due to side effects. Severe but not life-threatening side effects were observed in 17% of patients and included low blood platelet count, a deficiency of healthy red blood cells or hemoglobin, lack of energy and strength and fatigue.