Adoptive immunotherapy prevents prostate cancer in a transgenic animal model

Cancer-related mortality can be decreased by prevention, early detection an d improved therapies. Although animal models should be used to evaluate the success of cancer therapies, their usefulness is controversial. Many cance r therapies that have cured tumors in mice have not met with similar succes s when attempted in humans. Current animal models rely mainly on inoculatin g cell lines into animals, a method that does not reproduce the natural dev elopment of the tumor, both for the kinetics of induction and the anatomica l site concerned. In this study, we have used an SV40 T-antigen-transgenic mouse model of prostate cancer in which the tumor spontaneously develops or thotopically with a disease progression that closely resembles the progress ion of human prostate cancer. We have used this model to test the suitabili ty of adoptive cellular immunotherapy. Transfer of naive cells obtained fro m a T-antigen-negative congenic animal had significant but partial effects: it prevented development of malignant tumors, leaving just minor foci of r esidual tumor and/or hyperplasia. Adoptive transfer of memory lymphocytes s pecific for T-antigen, which is a prostatic self antigen in this model, pre vented tumor development and progression without affecting the morphology a nd function of involved tissues. Treated animals were able to breed, and th eir survival was greatly increased. These results strongly suggest that ado ptive immunotherapy should be successful in treating early stages of human prostate cancer.