Mutant Idh2 Cooperates with a NUP98-HOXD13 Fusion to Induce Early Immature Thymocyte Precursor ALL.

Mutations in the isocitrate dehydrogenase 1 (IDH1) and IDH2 genes are frequently observed in a wide variety of hematologic malignancies, including myeloid and T-cell leukemias. In this study, we generated Idh2R140Q transgenic mice to examine the role of the Idh2R140Q mutation in leukemia. No leukemia developed in Idh2R140Q transgenic mice, suggesting a need for additional genetic events for leukemia development. Because myeloid cells from NUP98-HOXD13 fusion (NHD13) transgenic mice frequently acquire somatic Idh mutations when they transform to acute myeloid leukemia, we generated Idh2R140Q/NHD13 double transgenic mice. Idh2R140Q/NHD13 transgenic mice developed an immature T-cell leukemia with an immunophenotype similar to double-negative 1 (DN1) or DN2 thymocytes. Idh2R140Q/NHD13 leukemic cells were enriched for an early thymic precursor transcriptional signature, and the gene expression profile for Idh2R140Q/NHD13 DN1/DN2 T-ALL closely matched that of human early/immature T-cell precursor (EITP) acute lymphoblastic leukemia (ALL). Moreover, recurrent mutations found in patients with EITP ALL, including KRAS, PTPN11, JAK3, SH2B3, and EZH2 were also found in Idh2R140Q/NHD13 DN1/DN2 T-ALL. In vitro treatment of Idh2R140Q/NHD13 thymocytes with enasidenib, a selective inhibitor of mutant IDH2, led to a marked decrease in leukemic cell proliferation. These findings demonstrate that Idh2R140Q/NHD13 mice can serve as a useful in vivo model for the study of early/immature thymocyte precursor acute lymphoblastic leukemia development and therapy. SIGNIFICANCE: T-cell leukemia induced in Idh2R140Q/NUP98-HOXD13 mice is immunophenotypically, transcriptionally, and genetically similar to human EITP ALL, providing a model for studying disease development and treatment.