The Nb with the highest affinity for PD-1, PD-1 Nb20, as measured by SPR (KD = 0.2 nM), was then further evaluated in combination with dendritic cell/tumor-fused cell (DC/tumor-FC) vaccines as an approach to enhance the anti-tumor efficiency of cytotoxic T lymphocytes (154). The gene discussed is PDCD1; the disease is neoplasm.