Combination cytokine therapy inhibits tumor growth by generation of tumor-specific T-cell responses in a murine melanoma model

Various cytokines, including interferon α (IFNα), tumor necrosis factor α (TNFα), and granulocyte-macrophage colony-stimulating factor (GM-CSF), have been used as adjuvant therapy for advanced-stage melanoma with some success but with marked toxicity, which appears to be related to higher doses. We investigated the efficacy of IFNα, GM-CSF, and TNFα in various combinations to induce antitumor and immune responses in a B16F10 murine melanoma model. These studies showed that GM-CSF, IFNα, and TNFα, when injected together intratumorally, mediated significant inhibition of tumor growth. Tumor regression correlated with local tumor necrosis and significant infiltration of T cells. In addition, this injected intralesional cytokine cocktail also induced lymphadenopathy, with an increase in both CD4⁺ and CD8⁺ T cells in the draining lymph nodes. Furthermore, tumor-specific CD8⁺ T cells were identified from draining lymph nodes. These investigations identify the combined effects of IFNα, GM-CSF, and TNFα in induction of the adaptive immune response and generation of antigen-specific T-cell reactivity. These results support potential clinical trials of the low-dose cytokine combination as adjuvant therapy for melanoma.