An orally bioavailable inhibitor of MPS1/TTK (IC50 = 1.7 nM); selective for MPS1/TTK over a panel of 262 kinases at 1 μM; increases aneuploidy in HCT116 cells at >100 nM; inhibits cell growth in a panel of breast, ovarian, prostate, pancreatic, lung, and colon cancer cell lines (GI50s = 0.001-1.3 μM); reduces tumor growth in HCT116 and HT29 mouse xenograft models as well as platinum-resistant and -sensitive high-grade serous ovarian cancer PDX mouse models at 6.5 mg/kg; inhibits CYP2C9 and CYP2C19 (IC50s = 13 and 8 μM, respectively) as well as CYP3A4 metabolism of BFC and DBF (IC50s = 0.51 and 14 μM, respectively)