Prevention of de novo prostate cancer by immunization with tumor-derived vaccines.
Since advanced prostate cancer is difficult to treat, we have chosen a very different approach: the development of vaccines to prevent initial de novo tumor formation. To test the hypothesis that prostate cancer can be prevented by vaccination, Lobund-Wistar (LW) rats were vaccinated subcutaneously with complete Freund's adjuvant (CFA) plus glutaraldehyde-fixed (GFT) whole cell or potassium thiocyanate extract (PTE) preparations derived from in vivo tumors, or with media and CFA (media-vaccinated). Rats were vaccinated each month substituting incomplete Freund's adjuvant for CFA, from age 3 to 12 months, and methylnitrosourea (30 mg/kg) was administered intravenously at 4 months of age. Groups of 30 GFT cell-vaccinated rats showed a 90% reduction, and PTE-vaccinated rats, a 50% reduction in the occurrence of de novo prostate tumors compared with media-vaccinated controls. When splenocytes from vaccinated rats were incubated with tumor cells prior to subcutaneous implantation, PTE-vaccinated rats showed a 80% reduction, and GFT cell-vaccinated rats showed a 40% reduction in the occurrence of tumors, demonstrating a role for the spleen in the protective response. The inflammatory responses in tumors from GFT cell-vaccinated rats and PTE-vaccinated rats were distinguished by an influx of eosinophils compared with the responses in tumors from media-vaccinated rats. These results demonstrate the possibility that prostate cancer can be prevented by immunization with vaccines based on whole tumor-derived vaccines.
Suckow
Mark A
MA
Lobund Institute, University of Notre Dame, 400 Freimann Life Science Center, Notre Dame, IN, 46556, USA. Suckow.1@nd.edu
Wolter
William R
WR
Pollard
Morris
M
D000818:Animals; D019496:Cancer Vaccines / Q000276:immunology*; D004804:Eosinophils / Q000502:physiology; D007114:Immunization; D008297:Male; D011471:Prostatic Neoplasms / Q000473:pathology / Q000517:prevention & control*; D051381:Rats; D013739:Testosterone / Q000097:blood
D019496:Cancer Vaccines; D013739:Testosterone