However, while immune checkpoint inhibitor monotherapy or combination therapy targeting cytotoxic T lymphocyte antigen 4 (CTLA-4) and/or programmed cell death-1 (PD-1)/PD-1 ligand 1 (PD-L1) axis has been regarded as the standard therapy in many solid tumours, mCRPC as ‘cold’ tumours are considered to be relatively resistant to ICB treatment. This evidence concerns the gene CTLA4 and neoplasm.