AXL/MERTK inhibitor ONO-7475 potently synergizes with venetoclax and overcomes venetoclax resistance to kill FLT3-ITD acute myeloid leukemia.

FMS-like Tyrosine Kinase 3 (FLT3) mutation is associated with poor survival in AML. The specific Anexelekto/MER Tyrosine Kinase (AXL) inhibitor ONO-7475 kills FLT3-mutant acute myeloid leukemia cells with targets including Extracellular-signal Regulated Kinase (ERK) and Myeloid Cell Leukemia 1 (MCL1). ERK and MCL1 are known resistance factors for Venetoclax (ABT-199), a popular drug for AML therapy, prompting the investigation of the efficacy of ONO-7475 in combination with ABT-199 in vitro and in vivo. ONO-7475 synergizes with ABT-199 to potently kill FLT3-mutant acute myeloid leukemia cell lines and primary cells. ONO-7475 is effective against ABT-199-resistant cells including cells that overexpress MCL1. Proteomic analyses revealed that ABT-199-resistant cells expressed elevated levels of pro-growth and anti-apoptotic proteins compared to parental cells, and that ONO-7475 reduced the expression of these proteins in both the parental and ABT-199-resistant cells. ONO-7475 treatment significantly extended survival as a single agent in vivo using acute myeloid leukemia cell lines and PDX models. Compared to ONO-7474 monotherapy, the combination of ONO- 7475/ABT-199 was even more potent in reducing leukemic burden and prolonging survival of mice in both model systems. These results suggest the ONO-7475/ABT-199 combination may be effective for acute myeloid leukemia therapy.