Future studies investigating cell proliferation (Ki67), apoptosis (annexin V, DAPI), exhaustion (LAG3, TIM3, PD-1, TIGIT), and anti-apoptosis gene expression (Bcl2, Bcl-xL) in BAL/PB cells between ICI-pneumonia and ICI-pneumonitis will enable us to dissect mechanisms of ICI-pneumonia and ICI-pneumonitis. Here, BCL2 is linked to susceptibility to pneumonia measurement.