Since the approval of olaparib and talazoparib for advanced human epidermal growth factor receptor 2-negative (HER2-negative) breast cancer, several phase IIIb–IV trials, expanded access cohorts, and retrospective cohorts have provided information on the efficacy and tolerability of these treatments in patient subgroups underrepresented in the registration trials, such as older adults, patients with poor performance status, and heavily pretreated patients. Here, ERBB2 is linked to breast carcinoma.