Pre-clinical studies in the B16/BL6 murine melanoma model have demonstrated that the Gvax plus anti-CTLA-4 blockade increased the number of tumor-infiltrating lymphocytes (TILs), attaining 1.4 × 106 TIL per gram of tumor tissue (approximately 109 tumor cells) (7), though it is difficult to explain how this effector/target ratio (1/1000) could achieve tumor regression. The gene discussed is CTLA4; the disease is neoplasm.