Human vaccine cures prostate tumors in mice

Using a human vaccine, researchers from Mayo Clinic, Rochester, MN and the United Kingdom appeared to cure well-established prostate tumors in mice, 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, researchers say.

"We are hopeful that this will overcome some of the major hurdles which we have seen with immunotherapy cancer research," said lead author Richard Vile, PhD, of Mayo Clinic.Clinical trials could begin within 2 years.

The team found no trace of autoimmune diseases in the mice. The murine T-cells attacked only cancerous prostate cells, leaving 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.

Development of comprehensive cDNA libraries from healthy human prostate tissue represents the key to successful immunotherapy, Dr. Vile explained. He deployed the human vaccine prostate cancer antigens through the mutated VSV vector to raise a full-on assault from the mice’s T-cells. After exposure to the mutated viruses, the animals’ immune systems recognized the antigens expressed in the virus and produced a potent immune response to attack the prostate tumors.

"By expressing all of these proteins in highly immunogenic viruses, we increased their visibility to the immune system," Dr. Vile said. "The immune system now thinks it is being invaded by the viruses, which are expressing cancer-related antigens that should be eliminated."

Study results were published online in Nature Medicine (June 19, 2011).