The in vivo experiments revealed that combination treatment with cordycepin and anti-PD-1 significantly reduced tumor size (Figure 6A) compared to combination treatment with adenosine and anti-PD-1, adenosine alone, cordycepin alone, and anti-PD-1 alone (p = 0.002, 0.002, 0.007, and 0.035, respectively). Here, PDCD1 is linked to neoplasm.