Previous studies showed that the combination of an anti-CD137 antibody with an anti-PD-L1 or anti-PD-1 antibody achieved better efficacy than monotherapy treatments in an HCC827 tumour model established with NSG mice implanted with human T cells or in a mouse UN-SCC680AJ syngeneic model23,24, suggesting a synergistic effect was achieved by combining checkpoint blockade and CD137 stimulation. This evidence concerns the gene PDCD1 and neoplasm.