Antitumor agent-172 (Compound 28) is an inhibitor for β-catenin/BCL9 interaction with IC 50 of 3.92 μM. Antitumor agent-172 exhibits high affinity to β-catenin with K d of 82 nM. Antitumor agent-172 activates T cells, promotes antigen presentation, and exhibits antitumor efficacy and good pharmacokinetic characteristics in mouse models.