IL4 Receptor-Targeted Proapoptotic Peptide Blocks Tumor Growth and Metastasis by Enhancing Antitumor Immunity

Cellular cross-talk between tumors and M2-polarized tumor-associated macrophages (TAM) favors tumor progression. Upregulation of IL4 receptor (IL4R) is observed in diverse tumors and TAMs. We tested whether an IL4R-targeted proapoptotic peptide could inhibit tumor progression. The IL4R-binding peptide (IL4RPep-1) preferentially bound to IL4R-expressing tumor cells and M2-polarized macrophages both in vitro and in 4T1 breast tumors in vivo To selectively kill IL4R-expressing cells, we designed an IL4R-targeted proapoptotic peptide, IL4RPep-1-K, by adding the proapoptotic peptide (KLAKLAK)₂ to the end of IL4RPep-1. IL4RPep-1-K exerted selective cytotoxicity against diverse IL4R-expressing tumor cells and M2-polarized macrophages. Systemic administration of IL4RPep-1-K inhibited tumor growth and metastasis in 4T1 breast tumor-bearing mice. Interestingly, IL4RPep-1-K treatment increased the number of activated cytotoxic CD8⁺ T cells while reducing the numbers of immunosuppressive regulatory T cells and M2-polarized TAMs. No significant systemic side effects were observed. These results suggest that IL4R-targeted proapoptotic peptide has potential for treating diverse IL4R-expressing cancers. Mol Cancer Ther; 16(12); 2803-16. ©2017 AACR.