Figure 6

Anti-tumor effects of combined therapy in models of pulmonary and hepatic metastases. A: Treatment regimen. B: Treatment effect in a pulmonary metastasis model. Cohorts of 20–22 week old ProHA x TRAMP mice (left panel) or non-transgenic (right panel) received I.V. injections of tumor cells (SP1) and were then treated with either combination or single-agent immunotherapy. N = 7 animals per group, representative of 2 independent experiments. *P < 0.05 (GVAX/anti-CTLA-4 vs. No Treatment.). C: Treatment effect in a hepatic metastasis model. Cohorts of 20–22 week old ProHA x TRAMP mice (left panel) or non-transgenic (right panel) received intra-splenic injection of tumor cells (SP1), followed by resection of the injected hemispleen to model isolated heptatic metastases. Animals were then treated with either combination immunotherapy or left untreated. N = 7 animals per group, representative of 2 independent experiments. *P < 0.05 (GVAX/anti-CTLA-4 vs No Treatment.). D: Addition of low-dose cyclophosphamide to combination immunotherapy. 20–22 week ProHA x TRAMP mice or non-transgenic mice were intravenously injected with the prostate cancer cell line (SP1). Cyclophosphamide (50 mg/kg) was administered 1 day before each GVAX injection. The treatment regimen was otherwise identical to that shown in 6A. N = 7 animals per group. Representative of 2 experiments. *P < 0.05 (Cy/GVAX/anti-CTLA-4 vs GVAX/anti-CTLA-4).