Macrophages expressing chimeric cytokine receptors have an inflammatory phenotype and anti-tumoral activity upon IL-10 or TGFß stimulation

Background Triple-negative breast cancer (TNBC) is a highly aggressive subtype of breast cancer that lacks hormone receptors and HER2 amplification, making it unresponsive to standard hormone or HER2-targeted therapies. Although immune checkpoint inhibitors (ICIs) have shown promise in tumors with high lymphocyte infiltration, their efficacy remains limited in tumors with minimal lymphocyte infiltration. To overcome this challenge, we developed a novel approach to reprogram tumor-associated macrophages (TAMs) from an immunosuppressive to an inflammatory phenotype within the tumor microenvironment (TME), aiming to enhance therapeutic outcomes in TNBC. Methods We designed a chimeric cytokine receptor (ChCR) that triggers STAT1 signaling upon stimulation with IL-10 or TGFß, cytokines prevalent in the TME that typically drive immunosuppression. Human primary macrophages were transduced with a lentiviral vector expressing the ChCR, and changes in their phenotype, secretome, and transcriptome were analyzed following stimulation. The anti-tumoral activity of these reprogrammed macrophages was assessed using co-culture assays with 3D TNBC spheroids. Results ChCR-expressing macrophages showed robust STAT1 activation in response to IL-10 or TGFß stimulation, resulting in an inflammatory phenotype similar to IFN? activation, as confirmed by phenotypic markers, and transcriptomic profiling. These ChCR-stimulated macrophages demonstrated significant anti-tumoral effects in 3D TNBC spheroids. Moreover, ChCR stimulation led to the upregulation of CXCL9 and CXCL10, chemokines essential for lymphocyte recruitment, and genes associated with good response to ICIs. Conclusion We successfully engineered a ChCR that reprograms TAMs within an IL-10- and TGFß-rich environment, inducing an inflammatory phenotype and anti-tumoral activity. The expression of CXCL9 and CXCL10 further supports lymphocyte recruitment, potentially facilitating greater lymphocyte infiltration and disrupting the immunosuppressive TME. This approach offers a promising strategy to improve immunotherapy outcomes in TNBC patients, particularly those with low immune cell infiltration, thereby addressing a critical unmet clinical need. Overall design: To characterize macrophages expressing ChCRs, we transduced primary human monocytes with lentivirus and differentiated them to macrophages. Macrophages were stimulated for 2 days (unstimulated, IL-10, TGFb or IFN?). Thereafter, gene expression was analyzed by bulk RNA sequencing.