Inhibiting SLAMF8 modulates tumor-associated macrophages and restores CD8+ T cell-mediated antitumor immunity in colorectal cancer.

SLAMF8 is predominantly expressed in macrophages and plays an important role in autoimmune diseases and inflammation. Our previous studies have focused on SLAMF8, however, the potential of SLAMF8 as an immunotherapeutic target and its role in regulating the tumor immune microenvironment remain to be elucidated. This study demonstrated that macrophage-specific SLAMF8 is significantly associated with a poor prognosis for colorectal cancer (CRC). Additionally, M2 macrophage and tumor-associated macrophages (TAMs) models were used to verify that SLAMF8 induces an immunosuppressive phenotype in macrophages and regulates antitumor immunity by inhibiting the activation and function of CD8+ T cells. In vivo, we confirmed that SLAMF8 inhibition promoted remodeling of the immunosuppressive microenvironment and augmented immunotherapy sensitivity in CRC. Mechanistically, we demonstrated that SLAMF8 promotes the polarization of macrophages toward the M2 phenotype via the PI3K/AKT and JAK/STAT3 signaling pathways. In summary, this study confirmed that inhibiting SLAMF8 exerts an antitumor effect by reversing the immunosuppressive tumor microenvironment in CRC, providing new therapeutic targets and strategies for combined immunotherapy.