Discovery of Novel Benzimidazole and Indazole Analogues as Tubulin Polymerization Inhibitors with Potent Anticancer Activities

Novel indazole and benzimidazole analogues were designed and synthesized as tubulin inhibitors with potent antiproliferative activities. Among them, compound 12b exhibited the strongest inhibitory effects on the growth of cancer cells with an average IC50 value of 50 nM, slightly better than colchicine. 12b exhibited nearly equal potency against both, a paclitaxel-resistant cancer cell line (A2780/T, IC50 = 9.7 nM) and the corresponding parental cell line (A2780S, IC50 = 6.2 nM), thus effectively overcoming paclitaxel resistance in vitro. The crystal structure of 12b in complex with tubulin was solved to 2.45 angstrom resolution by X-ray crystallography, and its direct binding was confirmed to the colchicine site. Furthermore, 12b displayed significant in vivo antitumor efficacy in a melanoma tumor model with tumor growth inhibition rates of 78.70% (15 mg/kg) and 84.32% (30 mg/kg). Collectively, this work shows that 12b is a promising lead compound deserving further investigation as a potential anticancer agent.

Automated summary

Novel indazole and benzimidazole analogues, such as compound 12b, demonstrated potent antiproliferative activities against cancer cells, with IC50 values comparable to colchicine. Compound 12b also showed in vivo antitumor efficacy in a melanoma tumor model, suggesting its potential as a promising lead compound for further investigation as a potential anticancer agent.