Interestingly, CD8+ TILs have enhanced expression of PD-1, TIM3, CD137 and LAG3 (% of each expression is 32.4%, 13%, 10.8%, 5.7%, respectively) in melanoma patients and nearly 80% of CD8+CD137+TILs express PD-1 [21]. This evidence concerns the gene TNFRSF9 and melanoma.