Assessment of Blocking Interleukin-17 Antibodies in Tumor Immunotherapy with Checkpoint Inhibitors or Tumor-Specific T Cells in Implanted and UVB-Induced Cancers

Background: Immune checkpoint inhibitors and adoptive T-cell therapies have substantially improved cancer treatment outcomes, but their use is often limited by immune-related toxicities, including cytokine release syndrome. The role of interleukin (IL)-17A in tumor immunity remains controversial, hindering its therapeutic applications in cancer. A concern is that application of IL-17 blocking agents to release cytokine storms caused by tumor immunotherapy reverses anti-tumor immunity. Methods: In this study, we evaluated the effect of IL-17A blockade alone and in combination with anti–PD (programmed cell death)-1 therapy or tumor-specific CD8+ T cells in melanoma, colon, and lung tumors, and in UVB-induced skin carcinogenesis. Results: Our results showed that blocking IL-17A inhibited tumor development, and did not impair the efficacy of tumor immunotherapies with checkpoint inhibitors or tumor-specific T cells. Combined treatment with anti-IL-17A and anti-PD-1 antibodies significantly enhanced tumor suppression compared to single-agent therapies in all tested tumor models. Moreover, IL-17A blockade improved the efficacy of adoptive CD8+ T-cell therapy. Mechanistic analyses revealed that the combination therapy increased infiltration of activated antigen-specific CD8+ T cells in tumors. In none of the tested tumor models did IL-17A blockade negatively affect the efficacy of tumor immunotherapy with checkpoint inhibitors or T-cell therapy. Conclusions: These findings suggest that the combined application of anti-IL-17A blocking agents with current tumor immunotherapy at the same time is a promising strategy to enhance the efficacy and potentially diminish immune-related adverse effects.