Despite progress in developing targeted therapies for certain breast cancer subtypes, since triple-negative breast cancers (TNBC) lack estrogen receptor (ER) and progesterone receptor (PR) and do not over-express the human epidermal growth factor receptor 2 (HER2), they are not amenable to current therapies that target those receptors. The gene discussed is ESR1; the disease is triple-negative breast carcinoma.