PDCD1 and triple-negative breast carcinoma: The development of immune checkpoint inhibitors (ICIs) targeting the adaptive immune system, such as programmed cell death protein-1 (PD-1) and its ligand PD-L1, and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), has improved outcomes in patients with advanced metastatic breast cancer and triple-negative breast cancer (TNBC) (6, 7).