That is, while HER2 positive breast cancers can be effectively targeted with Trastuzumab 7 and sometimes with Tamoxifen8, triple negative cancers lack effective targeted treatment due to its lack of cell surface receptors such as estrogen receptor (ER), progesterone receptor (PR) and human epithelial receptor 2 (HER2). The gene discussed is ESR1; the disease is breast carcinoma.