Carboplatin AUC5 can provide a comparable cytotoxic effect to carboplatin AUC6 in terms of pathologic complete response in patients with HER2+ breast cancer receiving neoadjuvant docetaxel/carboplatin/trastuzumab/pertuzumab (TCHP), with fewer complications associated with grade 3/4 anaemia. The gene discussed is ERBB2; the disease is breast carcinoma.