Tri-mAb in combination with IL-2 induced anti-tumor immunological memory. Long-term surviving mice were rechallenged with a subcutaneous injection of Renca (2 × 105 cells) and survival monitored. Mice were derived from groups of kidney tumor-bearing mice that received either 3 doses of Tri-mAb alone or in combination with IL-2. Some mice came from groups receiving only one dose of Tri-mAb with or without IL-2. A group of naive mice was also injected subcutaneously with Renca as controls for tumor growth in the absence of immunological memory. Numbers in parentheses depict the number of mice per group. (P2 = 0.012, Log-rank test; Tri-mAb + IL-2 vs Tri-mAb alone).