Large doses of IL-2 are necessary for optimal anti-tumor activity. Mice with established orthotopic disease were treated with Tri-mAb alone or in combination with various dose levels of IL-2 delivered in five doses as indicated. HD: high dose (105 IU); MD: medium dose (5 × 104 IU); LD: low dose (104 IU). Numbers in parentheses depict number of mice per group. Experiment performed once, P < 0.018 for high-dose IL-2 vs lower doses (Log-rank test).