CTLA4 and cancer: This combination therapy activates dendritic cells to prime tumor-specific CD8 T cells, while blocking CTLA-4 on regulatory T cells prevents immune suppression, leading to improved treatment outcomes in previously resistant cancers.294,295 Additionally, the presence of Tregs, which highly express CTLA-4, further contributes to an immunosuppressive microenvironment by outcompeting effector T cells for CD80/CD86 binding, thereby inhibiting effective immune responses.286,293