Given the preclinical data, along with the high frequency of PD-1 and CD137 co-expression on tumor-specific CD8+ tumor-infiltrating lymphocytes (TILs) found in humans, there is a clear mechanistic rationale for dual targeting of the PD-1/PD-L1 axis and CD137 to optimally engage anti-tumor immunity. Here, TNFRSF9 is linked to neoplasm.