Jun 20, 2011 - 2:10 pm
Human Vaccine Used to Cure Prostate Cancer in Mice
ScienceDaily (June 19, 2011) — Mayo Clinic investigators and collaborators from the United Kingdom cured well-established prostate tumors in mice using a human vaccine with no apparent side effects. This novel cancer treatment approach encourages the immune system to rid itself of prostate tumors without assistance from toxic chemotherapies and radiation treatments. Such a treatment model could some day help people to live tumor free with fewer side effects than those experienced from current therapies.
"We are hopeful that this will overcome some of the major hurdles which we have seen with immunotherapy cancer research," says Richard Vile, Ph.D., Mayo Clinic immunologist, Richard M. Schulze Family Foundation Professor and a lead author of the study. Clinical trials could begin within two years.
Mayo's immunotherapy research led by Dr. Vile already shows promise in treating prostate cancer and melanoma. It also is a prime candidate for treatment of many more aggressive cancers, such as lung, brain and pancreatic cancer. Among the team's findings: no trace of autoimmune diseases in the mice. The murine T-cells attacked only cancerous prostate cells, leaving the healthy tissue unharmed.
To develop this new approach, geneticists assembled snippets of genetic code from healthy human prostate tissue into a complementary DNA (cDNA) library. These bits of cDNA were then inserted into a swarm of vesicular stomatitis viruses (VSV), which were cultured and reintroduced into the test mice as a vaccine during a series of intravenous injections.
"Nobody really knows how many antigens the immune system can really see on tumor cells," says Dr. Vile. "By expressing all of these proteins in highly immunogenic viruses, we increased their visibility to the immune system. The immune system now thinks it is being invaded by the viruses, which are expressing cancer-related antigens that should be eliminated."
Previous attempts to vaccinate against prostate and other types of cancerous tumors have been hampered largely by researchers' inability to isolate a sufficiently diverse and robust collection of antigens in tumor cells. Because of this, tumors often mutate and re-establish themselves in spite of the body's immune system.
This study was a Mayo collaboration with Alan Melcher, Ph.D., and Peter Selby, Ph.D., both from the Cancer Research UK Clinical Centre at St. James' University Hospital and professors at the Leeds Institute of Molecular Medicine, University of Leeds, UK.
The National Institutes of Health, Cancer Research UK, The Richard M. Schulze Family Foundation, Mayo Clinic, and a private grant funded the study.