PDCD1 and colorectal cancer: Unprecedented advances have been made in cancer treatment with the use of immune checkpoint blockade (ICB).Antibodies targeting the checkpoint molecules cytotoxic T lymphocyte antigen 4 (CTLA4), programmed cell death 1 (PD1) and PD1 ligand 1 (PD-L1) have had early success in the clinic in several cancer types such as melanoma, lung cancer and colorectal cancers.Patients with recurrent cervical cancer have a poor prognosis.