Prostate Cancer Vaccine Elicits Immune Response
Phase I/IIa clincial trial results suggest vaccine is safe and biologically active
TUESDAY, July 28 (HealthDay News) -- A vaccine against a prostate tumor antigen is safe, elicits an immune response, and may increase prostate-specific antigen doubling time in patients with recurrent prostate cancer, according to an early-stage study published online July 27 in the Journal of Clinical Oncology.
As part of a phase I/IIa trial, Douglas G. McNeel, M.D., and colleagues from the University of Wisconsin in Madison immunized 22 patients with recurrent stage D0 prostate cancer intradermally with increasing amounts of DNA encoding the gene for human prostatic acid phosphatase (PAP), along with granulocyte-macrophage colony-stimulating factor as a vaccine adjuvant six times at 14-day intervals.
The researchers found that 55 percent of patients developed a PAP-specific T-cell response. There were no antibody responses or significant adverse events. The prostate-specific antigen doubling time increased significantly from a median of 6.5 months before treatment to 8.5 months during treatment, and to 9.3 months in the year after treatment.
"In summary, our results demonstrate that antigen-specific T cells were elicited after vaccination of patients with biochemical recurrence of prostate cancer using a DNA vaccine encoding PAP," McNeel and colleagues conclude. "These findings demonstrate biologic activity, suggest safety, and suggest possible effects on tumor growth rates."