Identification and Optimization of Novel Dual PARP/Tubulin Colchicine-Binding Site Inhibitors for Cancer Therapy

Abstract Dual targeting of poly(ADP-ribose) polymerase (PARP) and the colchicine-binding site (CBS) of tubulin represents a promising strategy to overcome tumor heterogeneity and acquired resistance. Herein, a series of benzofused heterocyclic carboxamide derivatives were designed and synthesized as novel dual PARP/CBS inhibitors. Structure−activity relationship studies identified D13 as the most potent lead, demonstrating low-nanomolar antiproliferative activities (IC50 = 2−15 nM) across multiple cancer cell lines with high selectivity over normal cells. D13 inhibited PARP1/2 enzymatic activity and suppressed tubulin polymerization via CBS binding. D13 also induced G2/M arrest, DNA damage, and apoptosis, while blocking cell migration and tube formation. In an MDA-MB-231 xenograft model, D13 at 20 mg/kg achieved 72.3% tumor growth inhibition with dose-dependent efficacy and good tolerability, outperforming veliparib, phenstatin, and their combination. These findings validate dual PARP/CBS inhibition as a viable therapeutic strategy and support further development of D13 as an anticancer lead.