A total of 613 fatal ICI toxicity events were reported in the WHO pharmacovigilance database (Vigilyze) from 2009 to January 2018, of which anti–PD-1/PD-L1-related deaths were usually from pneumonia (35%), followed by hepatitis (22%) and neurotoxicity (15%), whereas anti–CTLA-4–related deaths were mostly due to colitis (70%) (335). Here, CTLA4 is linked to hepatitis A virus infection.