Scientists appear to be one step closer to treating cancer with a vaccine after successful experiments on mice with prostate tumors.

The treatment is notable for leaving no traces of the autoimmune diseases in the mice, indicating that the vaccine only attacks the cancerous tissue, leaving healthy tissue unharmed.

"We are hopeful that this will overcome some of the major hurdles which we have seen with immunotherapy cancer research," said Professor Richard Vile, a Mayo Clinic immunologist and lead author of the study.

To create the vaccine, scientists used genetic code from a healthy human prostate and assembled the genetic code into a complementary DNA library. Complementary DNA is synthesized DNA tailored from particular types of DNA.

The key to developing the vaccine was building the complementary DNA library. By constructing a complementary DNA library of healthy prostate genetic code and blending it with vesicular stomatitis viruses and cancer antigens, the vaccine triggers the body's immune system to attack antigens and to recognize them in tumors.

Infections, from allergies to tumors, have a molecular tag, called an antigen, that sets off a response from the immune system.

Using antigens attached to viruses helps scientists overcome the challenge of isolating a diverse collection of antigens from tumor cells. When there are not enough types of antigens, tumors can re-establish themselves.

Vile hopes to begin clinical trials in two years.

The findings appear in the journal Nature Medicine.

The National Institutes of Health, Cancer Research UK, The Richard M. Schulze Family Foundation, Mayo Clinic, and a private grant funded the study.