Except for the critical roles of CD8+ T cells in anti-tumor immunity upon PD-1/PD-L1 blockades (2), CD4+ T cells are also demonstrated to be required for efficacious anti-tumor responses, such as the percentages of naive CD4+ T cells secreting certain cytokines including IFN-γ and TNF-α before receiving nivolumab, were significantly higher in patients with better response to anti-PD-1 therapy (3). This evidence concerns the gene PDCD1 and neoplasm.