The usefulness of mouse breast tumor models for testing and optimization of breast cancer vaccines at old age

Cancer is an age-related disease and with the graying of the society, there is an increasing need to optimize cancer management and therapy for application in elderly patients. Cancer vaccines that can be applied in both prevention and therapy are potentially less toxic than chemotherapy or radiation and could, therefore, be especially suitable for older more frail cancer patients. In this study, we used syngeneic metastatic (4TO7) and non-metastatic (64pT) breast tumor models to obtain valuable information on the potential usefulness of MAGE-encoding cancer vaccines in metastatic and non-metastatic breast cancer at old age. First, we tested a mouse Mage-b DNA vaccine in young mice and found a significant preventive effect on the development of metastases. However, little effect was observed on primary breast tumors. Second, we studied tumor progression in relation to aging and found significant smaller tumors in old compared to young mice. This was associated with an increase in the percentage of CD8⁺ T cells in the inguinal lymph nodes at the site of the tumor at old age. These findings suggest that breast cancer immunotherapeutic approaches could be a valid strategy even in elderly patients.