ERBB2 and breast cancer: pCR correlates with breast cancer prognosis and varies by tumor subtype, with the greatest response occurring in higher risk tumor biology [hormone receptor‐positive (HR+)/HER2−, 7%–15%; hormone receptor‐positive (HR+)/HER2+, 30%–40%; hormone receptor‐negative (HR−)/HER2+, 50%–70%; triple‐negative breast cancer (TNBC), 25%–30%).7, 8, 9, 10, 11, 12