CD274 and hypophysitis: As for irH induced by anti-PD-1 such as pembrolizumab, the pathogenesis of the few anti-PD-1 or PD-L1-induced cases of hypophysitis is not clear as IgG4 cannot activate the complement pathway and is less effective for antibody-dependent cell-mediated cytotoxicity (Vidarsson et al., 2014; Bruhns et al., 2009).