PDCD1 and neoplasm: The calculated molecular mass of nivolumab is 146 kDa [57], supporting the assertion that antibody-mediated inhibition of the PD-1/PD-L1 axis occurs external to tumor sites and that effector T-cells, activated against tumor-associated antigens in peripheral lymphoid tissues, enter the TME precoated with anti-PD-1 antibodies [52].