Meta-analysis of published anti-PD-1/PD-L1 and anti-CTLA-4 trials assessing their incidence using over 16 million adverse drug reaction data from the WHO pharmacovigilance database and records from 7 academic institutions showed widespread central pneumonia with anti-PD-1/PD-L1 monotherapy (115 [35%]), compared with pneumonitis with ipilimumab monotherapy (15 [8%]) 141. Here, CTLA4 is linked to pneumonitis.