Currently, clinical studies of two 4-1BB-specific agonistic antibodies, urelumab and PF-05082566, are ongoing, and the preliminary results support that 4-1BB agonism can promote the proliferation and activity of T cells and NK cells.221 Another clinical study used PF-05082566 combined with PD-1 antibody to treat NSCLC and renal cell carcinoma. Here, PDCD1 is linked to hereditary clear cell renal cell carcinoma.