JMX0293, an O-alkylamino-tethered salicylamide derivative, demonstrates strong efficacy against the TNBC MDA-MB-231 cell line with an IC50 of 3.38 μM, while showing minimal toxicity towards the non-tumorigenic human breast epithelial cell line MCF-10A, where its IC50 exceeds 60 μM. It inhibits STAT3 phosphorylation, contributing to apoptosis in MDA-MB-231 cells, and significantly suppresses MDA-MB-231 xenograft tumor growth in vivo, all without notable toxicity.