A gain-of-function EZH2 mutation was identified in 1 pt with FL, and this pt achieved a partial response. Median time to response overall was 3.7 (range 1.9–10.1) months (mo) and estimated median DOR for the 9 responding pts was 18.4...Valemetostat demonstrated encouraging clinical activity in pts with R/R B-NHL...Clinical responses were durable, with a median DOR of > 1.5...