In the examples of αCTLA-4 and αPD-1, these monoclonal antibody agents block CTLA-4 (reduces T-cell priming) and PD-1 (reduces cytotoxic T-cell activation) and subsequently their downstream signaling cascades, allowing for the continued activation, expansion, and effect of tumor-specific T-cell populations [19,20]. Here, PDCD1 is linked to neoplasm.