AMG 650 is a highly efficient and selective inhibitor targeting KIF18A, an overexpressed kinesin motor protein in human cancers. It selectively inhibits KIF18A MT-ATPase motor activity, displaying specificity towards various kinesin proteins. At concentrations affecting sensitive tumor cells, AMG 650 has minimal impact on the in vitro proliferation of human bone marrow mononuclear cells (>100 times). In vivo, AMG 650 exhibits low clearance, a long half-life, and favorable oral bioavailability. Additionally, when combined with the PARP inhibitor olaparib, AMG 650 enhances anticancer activity in tumor models with alterations in BRCA1 and CCNE1 compared to single-agent treatment.