Synergy of radiation therapy and immunotherapy in murine renal cell carcinoma.

The treatment of metastatic renal cell carcinoma with immunotherapy has resulted in objective anti-tumor responses in 15-30% of patients. To enhance the therapeutic effects of immunotherapy, it is becoming evident that this approach should be combined with other treatment modalities. In this study, a spontaneously metastasizing murine renal adenocarcinoma (Renca), transplanted under the renal capsule, was treated with either radiation therapy, immunotherapy or a combination of both. In order to distinguish between the local and systemic effects of radiation therapy, total body irradiation was compared to irradiation of the tumor-bearing kidney only, or irradiation of the whole mouse with the tumor-bearing kidney shielded. Immunotherapy was administered with interleukin-2 (IL-2) alone or with IL-2 and lymphokine activated killer (LAK) cells. Combined radiation and immunotherapy induced a better anti-tumor response than either modality alone. The best response was obtained by local tumor irradiation and IL-2 therapy and resulted in a significant reduction in primary tumor size, elimination of lung metastases and a significant increase in survival.