Enhancing the potency of a whole-cell breast cancer vaccine in mice with an antibody-IL-2 immunocytokine that targets exposed phosphatidylserine

Eighty percent of mice inoculated with 2aG4-IL2/4T1 vaccine survived free of tumor, as compared with 20% in the 2aG4/4T1 group, 20% in the C44-IL2/4T1 group, and none in the C44/4T1 control group (P = 0.001 for 2aG4-IL2/4T1 versus all others groups). The incidence, number of spontaneous lung metastases was significantly lower in the 2aG4-IL2/4T1 vaccinated group than in the other groups. Splenocytes from 2aG4-IL2/4T1 vaccinated mice had significantly higher 4T1 specific cytotoxicity and ability to secrete interferon-gamma (IFNγ) than did splenocytes from mice in the other groups. These results demonstrate that a potent whole-cell vaccine can be created by coating irradiated tumor cells with 2aG4-IL2. Such vaccine could potentially be an effective treatment modality for patients with residual disease or at “high-risk” for recurrence.