Darb-Esfahani and colleagues [36] reported a significantly increased progression free survival (PFS) in patients with higher PD-1 and PD-L1 expression in cancer cells, CD3+, PD-1+, and PD-L1+ TILs densities, as well as PD-1 and PD-L1 mRNA levels. Here, PDCD1 is linked to cancer.