A meta-analysis comprising more than 16,000,000 adverse drug reactions and involving 613 fatal irAEs found that anti–PD-1/PD-L1 fatalities were commonly due to pneumonitis (35%), hepatitis (22%), neurotoxic effects (15%), cardiac effects (8%), and myositis (7%) (Wang et al., 2018). Here, PDCD1 is linked to pneumonitis.