Pembrolizumab has shown promising effects and a good safety profile in PD-L1-positive advanced triple-negative breast cancer (KEYNOTE-012 study; NCT01848834) and in heavily pretreated ER+/HER2– breast cancer (KEYNOTE-028 study; NCT02054806) [49, 50]. Here, ERBB2 is linked to triple-negative breast carcinoma.