Researchers Say Experimental Treatment Is Effective for Advanced Prostate Cancer
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Reviewed By Louise Chang, MD
June 19, 2009 -- Mayo Clinic researchers say an experimental treatment may have cured two patients whose prostate cancers were so advanced they had been considered inoperable.
No one was more surprised than their doctors. "This is certainly not the way we thought it would go," Mayo urologist and immunologist Eugene Kwon, MD, tells WebMD.
He adds that the point of the treatment had been to buy some time for patients whose cancers appeared to be incurable.
The two men were originally enrolled in a study designed to determine if treatment to suppress testosterone (known as androgen ablation), followed by treatment with an experimental immunotherapy called ipilimumab, could slow the progression of advanced prostate cancer.
"The goal was to see if we could modestly improve upon current treatments," Kwon says.
The 85 patients in the study were not considered candidates for surgery, but several showed such dramatic regressions in their cancers that they left the trial in order to have it.
Kwon admits that this was done in the first patient not because the study investigators thought it was a good idea, but because the patient's wife insisted.
"Even though this patient had remarkable reduction in disease, we still did not think surgery would be beneficial," he says. "But in a two-hour, late-night phone conversation that became quite acrimonious, she demanded that we take her husband off the study and do surgery."
More than a year and a half later, that patient shows no signs of prostate cancer, Kwon says.
One other patient who also left the study to have surgery also appears free of the cancer, and a third patient was operated on last week.
"This occurred not because we as physicians and scientists were so brilliant, but because a patient's wife re-crafted our thinking about what was achievable," he says.
But just how promising is the treatment that Kwon and colleagues ended up with?
A prostate cancer specialist who spoke to WebMD says that remains to be seen.
"I think this is interesting information, but it is way too early to get exited," says Derek Raghavan, MD, PhD, who directs the Cleveland Clinic's Taussig Cancer Institute.
The study is ongoing and has yet to be published, but the researchers did present details on the patients who had the combination treatment and surgery in a poster presentation at a recent meeting of the American Society of Clinical Oncology.
Raghavan says prolonged androgen ablation is known to improve survival in locally advanced prostate cancer patients.
He adds that until more details of the trial are published, there is no way to independently assess the impact of ipilimumab on outcomes.
Ipilimumab is an experimental monoclonal antibody that targets a molecule on T-cells (a type of immune cell) that inhibits the immune system's ability to fight cancer cells. It has mostly been studied in melanoma patients.
"We and others have shown remarkable responses after initial androgen ablation in this group of patients," he says. "In this small, phase II study it is impossible to dissect out the impact of this ... antibody."
SOURCES: American Society of Clinical Oncology annual meeting, Orlando, Fla., May 29-June 2, 2009. Eugene Kwon, MD, urologist and immunologist, Mayo Clinic, Rochester, Minn. Derek Raghavan, MD, PhD, FACP, director, Cleveland Clinic Taussig Cancer Institute.
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