PDCD1 and neoplasm: Subgroup analysis of CheckMate 649 showed that high microsatellite instability and high tumor mutational burdens were associated with greater survival benefits from PD-1 blockade plus chemotherapy versus chemotherapy alone (Janjigian et al., 2021; Lei et al., 2022); and whether the incorporation of these features with PD-L1 expression can further improve patient selection is worthy of further investigation (Chen et al., 2023).