ERBB2 and breast cancer: As shown in the randomized phase III OlympiA trial, the poly ADP ribose polymerase (PARP) inhibitor olaparib is effective in patients with HER2-negative (HER2−) early breast cancer (eBC) who carry germline BRCA1 and BRCA2 mutations in the susceptibility genes BRCA1 and BRCA2 (gBRCA1/2 positive), that have received neoadjuvant or adjuvant chemotherapy and are at clinical high risk of relapse [5,6].