In this open-label, phase II, multicenter study in China (NCT03575065), patients with triple-negative breast cancer (TNBC cohort) or hormone receptor-positive (HR+)/HER2− breast cancer (HR+/HER2− cohort) and ≤ 2 prior lines of chemotherapy received pamiparib 60 mg orally twice daily in 28-day, continuous cycles. This evidence concerns the gene ERBB2 and breast cancer.