OM-153 is a potent and orally active tankyrase inhibitor with IC50s of 13 nM and 2 nM for tankyrase 1 and tankyrase 2 (TNKS1/2), respectively. OM-153 inhibits luciferase-based Wnt/β-catenin signaling reporter activity with an IC50 value of 0.63 nM. OM-153 shows inhibition of Wnt/β-catenin signaling and proliferation in COLO 320DM.