Unanimous approval recommendation driven by data on durable responses and disease stability, although some advisory committee members suggest limiting indication to second-line use; FDA comments suggest concerns about design and feasibility of planned confirmatory trial.

Low response rates in open-label, nonrandomized study raise questions about efficacy of the first-in-class EZH2 inhibitor relative to drugs currently used to treat the rare cancer, FDA says in advisory committee briefing document; retrospective natural history study also cannot be used to determine whether patients have better outcomes with tazemetostat than with available therapies.