Drug Delays Prostate Cancer Spread to Bones

Nov. 16, 2011— -- A new drug administered to prostate cancer patients has been found to delay the spread of cancer to the bones, according to a new study published in the Lancet.

The drug, known as denosumab, has been approved by the Food and Drug Administration for treatment of osteoporosis and prevention of fractures with bone metastases from solid tumors. Researchers believed it had potential to slow the progression of prostate cancer to the bones. Previous science has revealed that inhibiting of the cells that cause resorption of the bone can reduce the risk of the cancer's spread to the bone.

"Prostate cancer patients who develop bone metastases usually have poor outcomes, so preventing the development of metastasis has been a major unmet clinical need," Dr. Matthew Smith, lead author of the study and professor of medicine at Harvard Medical School, said in a statement. "This first demonstration of a treatment that can meet the goal is a significant accomplishment that should lead to better treatment strategies."

Smith serves as a consultant for Amgen, which marketed the drug and funded the study.

The research was based on more than 1,400 study participants from 30 different countries who were randomly assigned to receive injection treatments of the drug or a placebo each month over a two-year study period, when patients underwent bone scans and skeletal surveys to analyze the presence of metastases.

The men who participated in the study did not have tumors that had metastatized, but their cancer had not responded to hormone therapy.

The drug appeared to increase bone-metastasis-free survival by an average of four months more than the men who took the placebo. It did not increase survival overall, though. But patients were taken off the treatment when the cancer metastasized, which could explain the incongruous findings, experts said.

"This is the first agent of its kind to delay metastases, and not [through] chemotherapy or hormonal [treatment]," said Dr. David Crawford, head of urologic oncology at University of Colorado Health Sciences Center at Denver. "This will be a very important modality to use in high risk patients and yes patients should be optimistic there have been four new drugs approved in advanced prostate cancer in the last year."

Nearly all men who die of prostate cancer have bone metastases, because bone is the most common sites to which prostate cancer spreads. Cancer to the bones can lead to breaks, fractures and more surgery.

"This is certainly another step in the right direction," said Dr. Mitchell Gross, research director of the USC Westside Prostate Cancer Center."They were successful that the medicine delays development of the bone metastatic spread, but they didn't show it actually makes them live longer, so that's certainly a problem in some regards."

Gross said it's an exciting time to be in the prostate cancer field because several new treatments have come to light in the past year, including vaccine therapy and chemotherapy for advanced stage prostate cancer.

In an attached commentary to the study, Dr. Christopher J Logothetis of University of Texas' MD Anderson Cancer Center wrote: " The results of the study should serve as a catalyst to accelerate integration of mechanistic insight into study design, with the goal of selection of patient subsets for greatest therapeutic efficacy."