ERBB2 and breast cancer: Compared to standard chemotherapy alone, the addition of pembrolizumab improved pathologic complete response (pCR) rates in all breast cancer subtypes: 44% vs. 17% in HER2-negative breast cancers, 30% vs. 13% in HR-positive/HER2-negative breast cancers, and 60% vs. 22% in TNBC[39].