PDCD1 and neoplasm: In the phase II clinical trial of cryoablation combined with intratumoral immunotherapy for metastatic prostatic adenocarcinoma (NCT04090775), PD-1 inhibitor monoclonal antibody nivolumab and anti-CTLA-4 monoclonal antibody ipilimumab were sequentially injected directly into the tumor immediately following local cryoablation.