S-72 acts as a microtubule polymerization inhibitor, effective in cell-free assays at concentrations of 1, 3, and 10 µM. At nanomolar levels (IC50s = 15.64 and 26.32 nM, respectively), it diminishes the viability of both MCF-7 and paclitaxel-resistant MCF-7/T breast cancer cells. Moreover, at 50 nM, S-72 impedes migration, invasion, and wound healing in these cell lines. Additionally, at 100 nM, it arrests the cell cycle at the G2/M phase and induces apoptosis in MCF-7/T cells, while also inhibiting stimulator of interferon genes (STING) activation. In vivo, S-72 dosage at 15 mg/kg per day curtails tumor growth in mouse xenograft models of paclitaxel-resistant breast cancer, specifically MCF-7/T and MX-1/T.