Indium (III) thiosemicarbazone 5b is an anticancer compound demonstrating cytotoxicity against various cancer cell lines including A549, MCF-7 breast, cisplatin-resistant MCF-7/DDP breast, and Hl 7702 liver cancer cells, with IC50 values of 2.41, 1.97, 2.11, and 8.95 µM, respectively. It effectively lowers PI3K, Akt, mTOR, P-gp, and GSH levels in MCF-7/DDP cells. In vivo studies show that at a dosage of 2.5 µmol/kg, indium (III) thiosemicarbazone 5b significantly reduces tumor weight and volume in MCF-7/DDP mouse xenograft models. Furthermore, liposomes formulated with this compound promote apoptosis and pro-death autophagy in MCF-7/DDP cells, alongside notable reductions in tumor volume and weight, showcasing its potential as a therapeutic agent in cancer treatment.