Antitumor activity of an interleukin-2 monoclonal antibody in a murine osteosarcoma transplantation model.

Abstract

BACKGROUND: Injection of monoclonal antibody to interleukin-2 (S4B6) into mice depletes regulatory T-cells (Tregs) and exhibits antitumor activities mediated through an autoimmune reaction. In this study, we demonstrate that administration of S4B6 suppresses the murine osteosarcoma cell line, LM8. MATERIALS AND METHODS: LM8 osteosarcoma cells were transplanted subcutaneously into C3H mice (n=58). C3H mice were injected intraperitoneally with S4B6 starting at 7 days before LM8 transplantation (pre-S4B6 group), 2 days after transplantation, or 5 days after transplantation. Control group mice were injected with normal rat IgG. Mice were sacrificed and examined 4 weeks later. RESULTS: The number of pulmonary metastatic colonies and the tumor size were significantly reduced in the pre-S4B6 group compared to the control group. In addition, pulmonary metastases were inhibited in mice injected with S4B6 2 days, but not 5 days, after tumor transplantation. CONCLUSION: S4B6 administration inhibited metastasis even when injected 2 days after LM8 transplantation. Our data suggest that treatment with S4B6 might be suitable in a postoperative clinical setting.