A pCR can be achieved in 45–90 per cent of human epidermal growth factor receptor 2-positive (HER2+) tumours and triple-negative breast cancer (TNBC), but the rate in oestrogen receptor-positive (ER+)/HER2-negative (HER2–) breast cancer remains below 10 per cent3,5. The gene discussed is ERBB2; the disease is breast cancer.