Novel imidazo[1,2-a]pyridine-based tubulin polymerization inhibitors: Structure-activity relationships and anti-tumor immune potentiation.

Building on our previous research, a series of novel imidazo[1,2-a]pyridine derivatives were rationally designed and synthesized as tubulin polymerization inhibitors. Among these analogues, compound 5b exhibited the strongest antiproliferative activity against Jurkat, B16-F10, HCT116, and MDA-MB-231 cells, with IC values of 60 nM, 380 nM, 138 nM, and 1.054 μM, respectively. Further functional assays revealed that 5b can effectively suppress the migration and colony-forming capacity of B16-F10 cells. Mechanistically, compound 5b induced apoptosis and arrested the cell cycle in the G2/M phase by inhibiting tubulin polymerization. Molecular docking simulations revealed that 5b efficiently binds to the colchicine-binding pocket of tubulin, providing a structural basis for its activity. In vivo, compound 5b (10 mg/kg) demonstrated potent anti-tumor efficacy in a melanoma model without obvious systemic toxicity. Notably, 5b markedly potentiated the in vivo anti-tumor immune response through its combination with a PD-L1 monoclonal antibody (mAb), as evidenced by increased infiltration of cytotoxic CD8 effector T cells in tumor tissues. Collectively, these findings identify 5b as a promising tubulin polymerization inhibitor with immune-modulatory potential, meriting further investigation.