CTLA4 and susceptibility to pneumonia measurement: Since the clinical application of ICIs, at least nine death cases related to ICI-induced pneumonitis (PD1/PD-L1: 7 cases; PD1 plus CTLA4: 2cases) and ten death cases of fatal pneumonia associated with ICIs (CTLA4: 7 cases; PD1/PD-L1: 3 cases) have been reported (Table 1).