Figure 2.

Vaccination with scFv^N418-HER2 protects mice from challenge with HER2-expressing tumor cells and induces memory immune responses. A. Animals (10 mice per group) were vaccinated with HER2, neu, scFv^N418-HER2 or scFv^N418-neu on days -21 and -7. Control animals received pcDNA3.1. On day 0, mice were inoculated s.c. with D2F2/E2 tumor cells. Tumor developments were monitored, and animal survival was calculated. Left panel, kinetics of tumor growth; Right panel, survival curve. B. The vaccinated animals were challenged with parental HER2-negative D2F2 cells on day 0, Left panel, kinetics of tumor growth; Right panel, survival curve. C. The long-term surviving mice from scFv^N418-HER2 group were rechallenged with D2F2/E2, D2F2, or syngeneic unrelated 4T1 tumor cells 3 months after initial tumor challenge. D. Naive mice injected s.c. with D2F2/E2, D2F2, or 4T1 tumor cells served as a control. Tumor growth was followed by caliper measurements, and results are represented as the mean tumor volume (mm³). The data were representative of two experiments with comparable results. Bars, SE. *P < 0.001, scFv^N418-HER2 compared with other groups.