Two presently cancer-free patients do not necessarily add up to a viable cancer treatment. It certainly is encouraging news, however, given that the two patients who received an experimental drug therapy at the Mayo Clinic had inoperable, end-stage prostate cancer before beginning treatment.
Both men received the drug treatment in combination with standard hormone treatment and radiation therapy. The men were enrolled in an ongoing clinical trial of a drug called MDX-010, also known as ipilimumab, which is classified as an immunotherapeutic agent.
In both cases, according to the Mayo Clinic, researchers found that most of the cancer cells in the tumors shrank to the point where surgery could then be used to remove as much of the cancer as possible. Before the treatment, the men's tumors were far too involved in other tissues to allow surgery.
"We were startled to see responses that far exceeded any of our expectations," said Eugene Kwon, M.D., a Mayo Clinic urologist and leader of the clinical trial. "The candidates for this study were people who didn't have a lot of other options."
The researchers gave the patients a standard hormone therapy called androgen ablation. This removes testosterone from the men's systems and can yield modest tumor reduction. The patients then got a dose of ipilimumab. It reinforces the anti-tumor action of the testosterone reduction and causes a rapid and overwhelming immune response against cancer cells. With a few weeks, the men's tumors were so much smaller that surgery was possible. That's when the doctors realized the drug had dome something amazing.
"The tumors had shrunk dramatically," said Michael Blute, M.D., a Mayo urologist, who was co-investigator and who performed both surgeries. "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."
According to the Clinic, one of the men had subsequent radiation therapy. And both are now out of the hospital. This is hugely important work, which could eventually apply to other forms of cancer.
"This is one of the holy grails of prostate cancer research," said Dr. Kwon. "We've been looking for this for years."
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