CD8A and neoplasm: Neoantigen-driven B cell and Tfh cell collaboration was recently identified to promote robust antitumor CD8+ T cell responses and Tfh cell signatures correlated with GCs and prolonged survival in lung adenocarcinoma patients.6 Mechanistically, IL-21 production by Tfh cells was dependent on the presence of B cells and promoted CD8+ T cell-mediated tumor killing in mice.6 In this context, it is possible that increased Tfh cell function caused by anti-PD-1 treatment may not only affect humoral immune responses but also CTL-mediated immune responses directed against autoantigens.