IMMUNOTHERAPY OF PROSTATE-CANCER IN THE DUNNING RAT MODEL - USE OF CYTOKINE GENE MODIFIED TUMOR VACCINES

Adenocarcinoma of the prostate is the most common cancer in men. The m ajority of cancers are discovered once they have already metastasized, and there is no effective therapy for prostatic cancer at this stage. The use of cytokine-secreting tumor cell preparations as therapeutic vaccines for the treatment of advanced prostate cancer was investigate d in the Dunning rat R3327-MatLyLu prostatic tumor model. IL-2 secreti ng, irradiated, tumor cell preparations were capable of curing animals with s.c. established tumors, and induced immunological memory that p rotected animals from subsequent tumor challenge. Immunotherapy was le ss effective when tumors were induced orthotopically, but nevertheless led to improved outcome, significantly delaying, and occasionally pre venting, recurrence of tumors after resection of the cancerous prostat e. Granulocyte-macrophage colony stimulating factor secreting tumor ce ll preparations were less effective, and interferon-gamma secreting ce lls had only a marginal effect. Induction of a potent immune response in tumor bearing animals against the nonimmunogenic MatLyLu tumor supp orts the view that active immunotherapy warrants further investigation as a potential therapeutic approach to prostate cancer.