Immune checkpoint inhibitors (ICIs), such as pembrolizumab and atezolizumab, which disrupt the PD1–PDL1 interaction and stimulate cytotoxic T lymphocytes (CTLs), have been approved for patients with breast cancer, particularly those with HER2+ and triple-negative breast cancer (TNBC) [53,54,55,56]. This evidence concerns the gene ERBB2 and breast cancer.