IL4 and neoplasm: Similarly, recent studies have found that IL-4, traditionally considered a type 1 cytokine, in its Fc fusion form (Fc-IL-4), as a type 2 cytokine, enhances CD8+ T-cell activity by activating the STAT6 signaling pathway, thereby enhancing the antitumor effect of adoptive cell therapy and ICIs, and this conclusion has been verified in various tumor models [37].