To date, several predictive biomarkers have been associated with ICB outcomes in some cancers, including intratumoral expression of the inhibitory receptor PD-L1 (28), the tumor mutational landscape (29), immune gene signatures within the TME (30, 31), and the presence of tumor infiltrating lymphocytes (TILs) and their expression of PD-1/PD-L1 (32–35). Here, PDCD1 is linked to cancer.