IL7-TBRII, a Dual Cytokine Modulator Targeting IL-7 and TGF-β Pathways, Inhibits Tumor Progression and Metastasis

Abstract

Tumor-infiltrating CD8⁺ T cells are a key determinant of anti-tumor efficacy in immunotherapy. IL-7 has been explored as a cytokine therapy to expand CD8⁺ T cells, showing promising anti-tumor effects in preclinical models. However, clinical outcomes remain limited, likely due to the immunosuppressive tumor microenvironment. To enhance the efficacy of IL-7 therapy, we reanalyzed publicly available single-cell RNA-sequencing (scRNA-seq) data of tumors treated with IL-7, identifying elevated TGF-β signaling in CD8⁺ T cells following treatment. As TGF-β impairs CD8⁺ T cell function and antagonizes IL-7 signaling, we developed a bifunctional fusion protein, recombinant human IL-7 (rhIL-7)-hyFc-sTBRII (IL7-TBRII), by fusing a TGF-β trap (Fc-TBRII) to rhIL-7-hyFc (IL7-Fc). We evaluated the binding affinities and functionalities of each domain in vitro and in vivo, and assessed anti-tumor effects in the MC38 colon cancer model. IL7-TBRII demonstrated superior anti-tumor efficacy compared to IL7-Fc or Fc-TBRII alone, primarily through increased infiltration of cytotoxic CD8⁺ T cells into tumors. Also, IL7-TBRII expanded the number of activated CD44⁺ CD8⁺ T cells. Furthermore, IL7-TBRII reduced metastasis in the 4T1 breast cancer model by reshaping the immune cell composition, and demonstrated synergistic efficacy when combined with radiotherapy or anti-CTLA-4 therapy in the EMT6 breast tumor model. These findings suggest that dual modulation of the IL-7 and TGF-β pathways by IL7-TBRII effectively reprograms the immune microenvironment in both primary and metastatic tumors, particularly by promoting CD8⁺ T cell activation and infiltration, thus offering a promising strategy to improve clinical responses to immunotherapy.

Keywords: Immunotherapy; Interleukin-7; Recombinant fusion proteins; Transforming growth factor beta.