Ipilimumab, a CTLA-4 inhibitor is associated with higher rates of gastrointestinal (GI) toxicities, pruritus, rash, and hypophysitis whereas use of PD-1/PD-L1 antagonists is associated with higher risk of vitiligo, dysthyroidism, hepatotoxicity, and pneumonitis (Hamid et al., 2013; Weber J. S. et al., 2013; Brahmer et al., 2015; Eggermont et al., 2015, 2016; Herbst et al., 2016; Table 1 and Table S1). Here, CTLA4 is linked to pneumonitis.