A large retrospective data review of 5,038 NSCLC patients who received PD-1 (n=3,232) and PD-L1 (n=1,806) inhibitors found significantly higher incidence of pneumonitis with PD-1 (3.6%) than with PD-L1 (1.3%) inhibitors [12]. This evidence concerns the gene PDCD1 and pneumonitis.