ESR1 and breast cancer: The number of mutations with targeted therapies in breast cancer is ever increasing and currently includes genes such as poly (ADP-ribose) polymerase (PARP) (PARP inhibitors), p53 (vaccine therapy, gene therapy, Wee-1 inhibitors, Kevetrin), estrogen receptor alpha (ESR1) (alternative endocrine therapies), JAK1 (JAK1 inhibitors), and mTOR (mTOR inhibitors) [17].