Prostate Cancer Study Results Far Exceed Expectations
Reported June 23, 2009
(Ivanhoe Newswire) — Two Mayo Clinic patients whose aggressive prostate cancer tumors had grown well beyond the prostate into the abdominal areas and had been considered inoperable are now cancer free thanks in part to an experimental drug therapy.
The men were participating in a clinical trial of an immunotherapeutic agent called MDX-010 or ipilimumab. In these two cases, physicians say the ipilimumab initiated the death of a majority of cancer cells, causing the tumors to shrink sufficiently to allow surgery. “The goal of the study was to see if we could modestly improve upon current treatments for advanced prostate cancer,” Eugene Kwon, M.D., Mayo Clinic urologist and leader of the clinical trial is quoted as saying. “The candidates for this study were people who didn’t have a lot of other options. However, we were startled to see responses that far exceeded any of our expectations.”
The patients first received a type of hormone therapy called androgen ablation, which removes testosterone and usually causes some initial reduction in tumor size. Researchers then introduced a single dose of ipilimumab, an antibody which builds on the anti-tumor action of the hormone and causes a much greater immune response, resulting in massive death of the tumor cells. Both men experienced consistent drops in their prostate specific antigen (PSA) counts over the following weeks until both were deemed eligible for surgery.
The greatest surprise came during surgery. “The tumors had shrunk dramatically,” Michael Blute, M.D., Mayo urologist, co-investigator and surgeon, who operated on both men, is quoted as saying. “I had never seen anything like this before. I had a hard time finding the cancer. At one point the pathologist (who was working during surgery) asked if we were sending him samples from the same patient.”
One patient underwent radiation therapy after surgery; both have resumed their regular lives. Further research is being planned to understand more about the mechanisms of the antibody and how best to use the approach in practice.
The researchers note the significance of their findings.
“This is one of the holy grails of prostate cancer research,” says Dr. Kwon. “We’ve been looking for this for years.”
SOURCE: Discovery‘s Edge, Mayo Clinic research publication, June 20, 2009