SUMOylation inhibitor TAK-981 (Subasumstat) synergizes with 5-azacitidine in preclinical models of acute myeloid leukemia

Acute Myeloid Leukemias (AML) are severe hematomalignancies with dismal prognosis. The post-translational modification SUMOylation plays key roles in leukemogenesis and AML response to therapies. Here, we show that TAK-981 (subasumstat), a first-in-class SUMOylation inhibitor, is endowed with potent anti-leukemic activity in various preclinical models of AML. TAK-981 targets AML cell lines and patient blast cells in vitro and in vivo in xenografted mice with minimal toxicity on normal hematopoietic cells. Moreover, it synergizes with 5-azacitidine (AZA), a DNA-hypomethylating agent now used in combination with the BCL-2 inhibitor venetoclax to treat AML patients unfit for standard chemotherapies. Interestingly, TAK-981+AZA combination shows higher anti-leukemic activity than AZA+venetoclax combination both in vitro and in vivo, at least in the models tested. Mechanistically, TAK-981 potentiates the transcriptional reprogramming induced by AZA, promoting apoptosis, alteration of the cell cycle and differentiation of the leukemic cells. In addition, TAK-981+AZA treatment induces many genes linked to inflammation and immune response pathways. In particular, this leads to the secretion of type I interferon (IFN-I) by AML cells. Finally, TAK-981+AZA induces the expression of Natural Killer (NK)-activating ligands (MICA/B) and adhesion proteins (ICAM-1) at the surface of AML cells. Consistently, TAK-981+AZA-treated AML cells activate NKs and increase their cytotoxic activity. Targeting SUMOylation with TAK-981 may thus be a promising strategy to both sensitize AML cells to AZA and reduce their immune-escape capacities. Total RNA from U937 cells treated for 3 days with 10nM of either TAK-981, 5-azacitidine or the combination of TAK-981 + 5-azacitidine were sequenced in 3 biological replicates.