Novel Triazoloquinoxaline-Based Tubulin Polymerization Inhibitor Induces Necroptosis and Significantly Inhibits Metastatic Melanoma Tumor Growth

Metastatic melanoma is the deadliest form of skin cancer, being responsible for 80% of skin cancer deaths. Small molecule colchicine-binding site inhibitors have previously demonstrated preclinical therapeutic efficacy in treating metastatic and paclitaxel-resistant melanoma. We report here on the design, synthesis, and biological evaluation of thirty-five novel triazoloquinoxaline-based compounds with promising therapeutic potential. The most potent analog, <b>9d</b>, showed strong antiproliferative activity against a panel of melanoma cell lines (GI₅₀ = 15.4 nM against A375) and binds to the colchicine site. Treatment with <b>9d</b> in vitro arrests the cell cycle in the G2/M phase and induces apoptosis. In vivo, compound <b>9d</b> (10 mg/kg) demonstrated a good safety profile, significantly inhibited tumor growth and proliferation, and induced leukocyte infiltration along with apoptosis and necroptosis in an immunocompetent B16-F10 syngeneic mouse model. Further evaluation of <b>9d</b> has characterized its unique mechanism of inducing both apoptosis and necroptosis in treated melanoma cells.