FIGURE 5.
Active treatment of established pulmonary metastases correlated with viral titer administered and was improved with the addition of exogenous rIL-2. Groups of five or six mice were inoculated i.v. with 1 × 105 cells/mouse of CT26.CL25 or CT26.WT. Three days later, mice were immunized with rAd-CMV2 or rAd-Empty in doses of 1 × 107 and 1 × 108 iu/mouse. Additionally, some mice were randomized to receive 90,000 IU of exogenous rIL-2 twice a day for a total of 3 days. Fourteen days after tumor administration, mice were killed, and pulmonary metastases were counted blindly. The magnitude of the anti-tumor response, as represented by the mean number of pulmonary metastases, correlated in a dose-dependent fashion with the viral titer administered. Exogenous rIL-2 shifted the dose-response curve such that lower viral titers were needed to achieve equivalent results. Nonparametric statistical analysis was performed with a two-tailed Wilcoxon’s test. An independent repetition of this experiment confirmed these results.