Among the various PARPi, olaparib has been approved by the Food and Drug Administration (FDA) for the treatment of ovarian, breast, and prostate cancers while talazoparib has been approved for treating human epidermal growth factor receptor 2 (HER2)-negative locally advanced or metastatic breast cancer or BRCA-deficient breast cancers and rucaparib and niraparib have been approved for treating ovarian cancer. This evidence concerns the gene ERBB2 and breast cancer.