PDCD1 and cancer: The use of immune checkpoint inhibitors (ICIs) targeting programmed cell death-1 (PD-1)/programmed death ligand-1 (PD-L1) and cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) is a promising strategy for the treatment of recurrent ovarian cancer and could be more effective for OCCC than for other histological cancer types [1, 2].