LAUSR

Simple Summary Acute myeloid leukemia (AML) with mutations in the tumor suppressor gene TP53 is rapidly lethal for most patients. Here, we investigated the preclinical activity of TP-0903, a multikinase inhibitor that inhibits kinases with potential synthetical lethality in TP53 mutant AML. TP-0903 inhibited cell viability and induced apoptosis in multiple TP53 mutant AML cell lines at nanomolar concentrations in vitro. TP-0903, both alone and in combination with decitabine, the current standard of care, improved survival in two xenograft models of TP53 mutant AML. These results demonstrate that TP-0903 has activity in AML with TP53 dysfunction and support the clinical evaluation of TP-0903 in combination with decitabine in TP53 mutant AML. Abstract Acute myeloid leukemia (AML) with mutations in the tumor suppressor gene TP53 confers a dismal prognosis with 3-year overall survival of <5%. While inhibition of kinases involved in cell cycle regulation induces synthetic lethality in a variety of TP53 mutant cancers, this strategy has not been evaluated in mutant TP53 AML. Previously, we demonstrated that TP-0903 is a novel multikinase inhibitor with low nM activity against AURKA/B, Chk1/2, and other cell cycle regulators. Here, we evaluated the preclinical activity of TP-0903 in TP53 mutant AML cell lines, including a single-cell clone of MV4-11 containing a TP53 mutation (R248W), Kasumi-1 (R248Q), and HL-60 (TP 53 null). TP-0903 inhibited cell viability (IC50, 12–32 nM) and induced apoptosis at 50 nM. By immunoblot, 50 nM TP-0903 upregulated pChk1/2 and pH2AX, suggesting induction of DNA damage. The combination of TP-0903 and decitabine was additive in vitro, and in vivo significantly prolonged median survival compared to single-agent treatments in mice xenografted with HL-60 (vehicle, 46 days; decitabine, 55 days; TP-0903, 63 days; combination, 75 days) or MV4-11 (R248W) (51 days; 62 days; 81 days; 89 days) (p < 0.001). Together, these results provide scientific premise for the clinical evaluation of TP-0903 in combination with decitabine in TP53 mutant AML.