Tp53 and Tet2 mutations cooperatively transform GMP (RNA-Seq)

Mutations and deletions in TP53 are associated with adverse outcome in patients with myeloid malignancies and developing improved therapies for TP53-mutant leukemias is of urgent need. Here we identify mutations in TET2 as the most commonly co-existing mutation in TP53 mutant acute myeloid leukemia (AML) patients. Combined hematopoietic-specific deletion of TET2 and TP53 in mice enhanced self-renewal compared to deletion of either gene alone. Tet2/Tp53 double knockout mice developed serially transplantable AML. Both mice as well as patients with AML and combined TET2/TP53 alterations upregulated innate immune signaling in malignant cells. Mice with TET2/TP53 loss had expansion of monocytic myeloid-derived suppressor cells which impaired T cell proliferation. Moreover, patients and mice with TP53/TET2 double mutant AML upregulated TIGIT ligands CD155 on malignant cells. TIGIT blocking antibodies augmented the ability of NK cells to kill Tet2/Tp53 double mutant AML cells, reduced leukemic burden, and extended the survival of TET2/TP53 double knockout mice. These data thereby identify a previously unexplored link between TET2 and TP53 mutations and highlight therapeutic means to overcome the immunosuppressive bone marrow environment in this adverse subtype of AML. To understand the molecular mechanisms underlying AML transformation upon combined mutation in TET2 and TP53, we performed limiting cell RNA-seq of GMP (lin-cKit+Sca-1-CD16/32+CD34+) cells from diseased Vav-cre Tet2fl/fl Tp53fl/fl mice developing AML and age-matched Vav-cre Tp53fl/fl, Vav-cre Tet2 fl/fl, and WT mice.