Patients experienced a decrease in bone pain after receiving cabozantinib
For patients with prostate cancer that had spread to the bone, a new drug exhibited remarkable and quick effects, according to a study reported by University of Michigan Comprehensive Cancer Center researchers. Results of the study appear in the Journal of Clinical Oncology.
Designed to target 2 pathways linked to the growth and spread of prostate cancer, cabozantinib had the most effect on tumors that had spread to the bone. Nearly two-thirds of the patients treated with cabozantinib had improvements on their bone scans, with 12% showing complete resolution of uptake on bone scan. These scan improvements 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, MD, professor of internal medicine and urology at the University of Michigan Medical School.
Along with the bone scan improvements, 67% of patients with bone pain reported progress in pain control, and 56% decreased or eliminated narcotic painkillers following treatment with cabozantinib.
The trial enrolled 171 men with castration-resistant prostate cancer and began as a randomized trial in which all patients received cabozantinib for 12 weeks. After the initial 12-week period, patients were randomized to continue cabozantinib or to receive placebo. However, randomization was stopped prematurely due to the remarkable effects on bone scan. Also, cancers progressed much more quickly in patients receiving placebo compared to those who remained on drug.
Among the 31 patients who were randomized, cancer progressed after a median of 5.9 weeks for patients on placebo compared with 23.9 weeks for patients taking cabozantinib.
“Discontinuing randomization is not common. Stabilization of disease in advanced prostate cancer is rarely due to the natural history of the disease and is in this case due to drug effect,” Smith says.
University of Michigan researchers are conducting a phase 2 study to better understand cabozantinib’s effect on bone.
Source: University of Michigan Health System.