ERBB2 and breast cancer: The first results of phase I a/b and phase II clinical trials have been generated, carried out in monotherapy in different BC immunophenotypes, although mostly focused on metastatic TNBC with positive PD-L1 expression, such as the KEYNOTE 12 study (NCT01848834) with pembrolizumab, the PCD4989g trial (NCT01375842) with atezolizumab, or the JAVELIN study (NCT01943461) with avelumab incorporated TNBC, HER2+ and ER+/HER2- patients, among others [97].