Ex vivo drug sensitivity assays demonstrated the highly selective efficacy of FGFR inhibitors in ZMYM2::FGFR1 fusion-positive leukemia cells and a fusion-expressing BaF3 cell line….Ex vivo drug assays performed on ZMYM2::FGFR1 transformed BaF3 cells confirmed the efficacy of Pemigatinib and Ponatinib....Despite extensive screening, no other single agents or drug combinations exhibited increased effectiveness in the ZMYM2::FGFR1 transformed BaF3 cells except for Trametinib, a MEK inhibitor, and the combination of Belvarafenib (RAF inhibitor) and Gilteritinib (FLT3 inhibitor).