ESR1 and triple-negative breast carcinoma: Decreases survival in hormone receptor-positive cell lines MCF-7 and T47D with low nanomolar potency.Destabilizes estrogen receptor (ER) and progesterone receptor (PR) in a dose-dependent manner.Shows strong anticancer activity in vivo by inhibiting expression and survival of ER/PR proteins in hormone receptor-positive cells.Prevents triple-negative breast cancer (TNBC) cells from expressing oncogenic signals and growing tumors.Proves highly cytotoxic to the inflammatory breast cancer (IBC) cell line SUM149.