Direct inhibition of CTLs by IL-6 is mechanistically distinct from other cytokine-dependent processes that can potentially inhibit ICI efficacy, including recruitment of inhibitory myeloid cells by VEGF,56 IL-1β,57 IL-8,58,59 or LIF,60 suppression of tumor CTL infiltration by TGFβ,61 and support of Treg function by IL-23.62 This evidence concerns the gene LIF and neoplasm.