This paper elucidates the multifaceted roles of key cytokines, such as IL-2, IL-7, IL-10, IL-12, IL-15, IL-18, and IL-21, in modulating T cell behavior, improving persistence, and overcoming the immunosuppressive barriers of the tumor microenvironment (Table 1) (23, 89, 125, 126). This evidence concerns the gene IL21 and neoplasm.