The severity of ICI-related pneumonitis is graded per the Common Terminology Criteria for Adverse Events V.4.03 and the management of respective grades are outlined elsewhere.5 A meta-analysis that included data from 20 clinical trials and nearly 4500 patients with solid tumors showed that the incidence of ICI-related pneumonitis was 2.7% and up to 4% of patients discontinued ICIs due to pulmonary toxicity.6 The risk is considerably higher with PD-1 inhibitors as compared with CTLA-4 or PD-L1 inhibitors. This evidence concerns the gene CTLA4 and pneumonitis.