HI-TOPK-032 is a potent and selective TOPK inhibitor. In vitro, HI-TOPK-032 strongly suppressed TOPK kinase activity but had little effect on extracellular signal–regulated kinase 1 (ERK1), c-jun—NH2—kinase 1, or p38 kinase activities. HI-TOPK-032 also inhibited anchorage-dependent and -independent colon cancer cell growth by reducing ERK-RSK phosphorylation as well as increasing colon cancer cell apoptosis through regulation of the abundance of p53, cleaved caspase-7, and cleaved PARP. In vivo, administration of HI-TOPK-032 suppressed tumor growth in a colon cancer xenograft model. HI-TOPK-032 may be further developed as a potential therapeutic against colorectal cancer. The serine-threonine mitogen-activated protein kinase kinase family member T-LAK cell–originated protein kinase (TOPK/PBK) is heavily involved in tumor development, cancer growth, apoptosis, and inflammation ( Cancer Res; 72(12); 3060–8.).