BRCA1/2 mutant breast cancer cells are more sensitive to poly (ADP-ribose) polymerase (PARP) inhibitors because of the synthetic lethal mechanism [29], and olaparib has been approved for the adjuvant treatment of gBRCAm, HER2-negative high-risk early breast cancer and gBRCAm, HER2-negative locally advanced or metastatic breast cancer [30]. The gene discussed is ERBB2; the disease is breast cancer.