Tumors were reduced on bone scans, bone pain decreased after patients received cabozantinib
A new drug demonstrated dramatic and rapid effects on prostate cancer that had spread to the bone, according to a study reported by University of Michigan Comprehensive Cancer Center researchers.
About two-thirds of patients treated with cabozantinib had improvements on their bone scans, with 12% seeing complete resolution of uptake on bone scan. Bone scans assess the degree to which cancer is in the bone; improvements on these scans suggest a response to the drug.
“The effects of cabozantinib on bone scans are unprecedented in the treatment of prostate cancer,” says lead study author David C. Smith, M.D., professor of internal medicine and urology at the University of Michigan Medical School.
Cabozantinib is designed to target two important pathways linked to the growth and spread of prostate cancer. The drug had the most effect on tumors that had spread to the bone, which is the major site where prostate cancer spreads. These tumors are typically very challenging to treat once they become resistant to hormone-based therapies.
In addition to the improvements on bone scans, 67% of patients with bone pain reported an improvement in pain control and 56 percent decreased or eliminated narcotic painkillers after treatment with cabozantinib.
The trial enrolled 171 men with castration-resistant prostate cancer, meaning their tumors no longer responded to hormone-based therapies. The study began as a randomized trial in which all patients received cabozantinib for 12 weeks, after which patients were randomized to receive continued cabozantinib or placebo. The randomization was stopped early because of the dramatic effects on bone scan, and because patients receiving placebo saw their cancer progress much more quickly than those that remained on drug.
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