Vinokurova, DariaApetoh, Lionel2023-11-292023-11-292023-04-12Vinokurova D, Apetoh L. The Emerging Role of IL-9 in the Anticancer Effects of Anti-PD-1 Therapy. Biomolecules. 2023;13(4):670. Published 2023 Apr 12. doi:10.3390/biom13040670https://hdl.handle.net/1805/37216PD-1 blockade rescues failing anticancer immune responses, resulting in durable remissions in some cancer patients. Cytokines such as IFNγ and IL-2 contribute to the anti-tumor effect of PD-1 blockade. IL-9 was identified over the last decade as a cytokine demonstrating a potent ability to harness the anticancer functions of innate and adaptive immune cells in mice. Recent translational investigations suggest that the anticancer activity of IL-9 also extends to some human cancers. Increased T cell-derived IL-9 was proposed to predict the response to anti-PD-1 therapy. Preclinical investigations accordingly revealed that IL-9 could synergize with anti-PD-1 therapy in eliciting anticancer responses. Here, we review the findings suggesting an important contribution of IL-9 in the efficacy of anti-PD-1 therapy and discuss their clinical relevance. We will also discuss the role of host factors like the microbiota and TGFβ in the tumor microenvironment (TME) in the regulation of IL-9 secretion and anti-PD-1 treatment efficacy.en-USAttribution 4.0 InternationalTH9 cellsAnti-PD-1Cancer immunotherapyInterleukin 9Article