These findings demonstrate that the title compounds do not display significant cytotoxicity effects against MCF-7 cells when compared with letrozole (10) (positive control, IC50 = 20 μM) [27], a drug that is usually prescribed for the treatment of estrogen receptor-positive (ER-positive) breast cancer subtypes, represented here by MCF-7 cells [34]. The gene discussed is ESR1; the disease is breast carcinoma.