Used in cancer immunotherapy to stimulate the immune system against tumors. Binds to CD27, a costimulatory receptor on T cells, enhancing T cell activation, proliferation, and persistence. Promotes anti-tumor immune responses by boosting both primary and memory T cell activity. Investigated in clinical trials for solid tumors and hematologic malignancies, often in combination with other immunotherapies like checkpoint inhibitors. Shows potential for improving immune-mediated tumor clearance.