Tazemetostat produces objective response in epithelioid sarcoma with loss of INI1/SMARCB1

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Tazemetostat showed clinical activity in patients with advanced epithelioid sarcoma with loss of INI1/SMARCB1, according to a study in The Lancet Oncology.

More than 90% of epithelioid sarcoma tumors have lost INI1 expression.

In this open-label, phase 2 basket study, 62 patients with epithelioid sarcoma with documented loss of INI1 expression received 800 mg tazemetostat orally twice per day in continuous 28-day cycles until disease progression, unacceptable toxicity, or withdrawal of consent.

At the data cutoff date, 15% (n = 9) of patients had an objective response. The median duration of response was not reached at a median follow-up of 13.8 months. At 32 weeks, 26% (n = 16) of patients had disease control and the median time to response was. 3.9 months.

Median progression-free survival and median overall survival were 5.5 months and 19 months, respectively.

Grade 3 or worse treatment-related adverse events included anemia in 6% (n = 4) of patients and weight loss in 3% of patients (n = 2). There were 2 treatment-related serious adverse events of seizure (n = 1) and hemoptysis (n = 1). No treatment-related deaths were reported.

The authors concluded that “Tazemetostat has the potential to improve outcomes in patients with advanced epithelioid sarcoma.”

A phase 1b/3 trial of tazemetostat plus doxorubicin is currently underway.


Gounder M, Schöffski P, Jones RL, et al. Tazemetostat in advanced epithelioid sarcoma with loss of INI1/SMARCB1: an international, open-label, phase 2 basket study. Lancet Oncol. 2020;21(11):1423-1432. DOI: 10.1016/S1470-2045(20)30451-4.