The incidence of Grade 3–4 irAEs with single-agent anti-CTLA-4 ipilimumab at 3 mg/kg dosing (while used at 1 mg/kg in NSCLC), was reported to be 26% in the randomized Phase 3 trial CheckMate 067 [7], while the two nivolumab registration trials for second-line setting, in squamous and non-squamous NSCLC, at 3 mg/kg dosing, reported lower rates from 7 to 10% [2,3], similar to the 13.6% incidence of Grade 3–5 irAEs in the Phase 3 first-line pembrolizumab trial [4]. Here, CTLA4 is linked to non-small cell lung carcinoma.