Ordinarily, vaccines refocus and retrain the body's natural defenses and put them to work attacking diseases before they have a chance to do any harm. In a new twist on the old vaccine, researchers at the Mayo Clinic and in the U.K. have successfully produced a vaccine that turns the immune system against an already existing prostate cancer tumor. The researchers, writing in Nature Medicine, say they cured "well-established" prostate cancer in mice with "no apparent side effects," raising hope for a treatment that avoids toxic chemotherapy and radiation treatment.
"Although the vaccine didn't trigger the immune system to overreact and cause serious side effects in mice, it will need to be further developed and tested in humans before we can tell whether this technique could one day be used to treat cancer patients," Peter Johnson, Cancer Research U.K.'s chief clinician, told BBC.
Here's what they did: The scientists snipped pieces of genetic code from healthy human prostates and assembled them into a complementary DNA (cDNA) library. The cDNA were tacked onto a virus and and then injected into mice. The virus produced antigens, which triggered a full-on assault from the body's immune system against the prostate tumors.
"Nobody really knows how many antigens the immune system can really see on tumor cells," the Mayo Clinic's Richard Vile said in a release. "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."
Alan Melcher, of the University of Leeds, told the BBC that developing antigens that can target tumors without causing harm elsewhere is "the biggest challenge in immunology."
It seemed to work in mice, anyway, with 80 percent of the rodents cured of prostate cancer. Kate Holmes, research manager at the Prostate Cancer Charity, told the BBC that the study provides "new hope," but cautioned that it's only a potential treatment that still need to be tried on humans. That won't happen for another couple of years. That, however, did not stop the researchers from getting to work on the same vaccine principle against other cancers such as melanoma.
- read the release from the Mayo Clinic
- the BBC filed this report
- and read the abstract in Nature Medicine