Early/immature T cell precursor acute lymphoblastic leukemia (EITP ALL) represents a subset of human leukemias distinct from other T-ALL, and associated with poor prognosis. Clinical studies have identified chromosomal translocations involving the NUP98 gene and point mutations of IDH genes as recurrent mutations in patients with EITP-ALL. In a recent study using genetically engineered mice, we demonstrated that cooperation of an Idh2 mutation with a NUP98-HOXD13 (NHD13) fusion gene resulted in EITP-ALL. Highlights of this double transgenic mouse model included the similarity of the immunophenotypic, mutational and gene expression landscape with human EITP-ALL. Additional studies showed that the Idh2 /NHD13 EITP-ALL are sensitive to selective mutant IDH2 inhibitors in vitro, leading to the possibility that these mice can serve as a useful model for the study of EITP ALL development and therapy.