We have previously reported that ITR-284, a potent carboxamide-derived anticancer agent, induced apoptosis in leukemia cells. However, there are no reports showing that ITR-284 inhibits human hepatocellular and colorectal cancer cells. In this study, we investigated the antiproliferative effects and apoptotic induction of ITR-284 on various types of human hepatocellular and colorectal cancer cells in vitro. The growth inhibition effect of ITR-284 on cancer cells was evaluated by thiazolyl blue tetrazolium bromide (MTT) assay. Cell morphology was examined under a phase-contrast microscope. The activities of caspase-3, -8 and -9 were determined by caspase colorimetric assay. ITR-284 reduced the cell viability in human hepatocellular cancer cells (Hep G2, Hep 3B, SK-HEP-1 and J5) and colorectal cancer cells (HT 29, COLO 205, HCT 116 and SW 620). ITR-284 had highly selective effects on Hep 3B and COLO 205 cells. ITR-284 stimulated morphological changes of Hep 3B and COLO 205 cells. The activation of caspase-3, -8 and -9 contributed to ITR-284-induced apoptosis. ITR-284-triggered growth inhibition was significantly attenuated by the inhibitors of caspase-3, -8 and -9 in Hep 3B and COLO 205 cells. ITR-284 induced apoptosis in Hep 3B and COLO 205 cells through the caspase cascade-dependent signaling pathway.