Cabozantinib (Cometriq) Shows Promise in Prostate Cancer Spread to Bone
Tumors reduced on bone scans (Dec. 4)
Cabozantinib (Cometriq, Exelixis, Inc.) demonstrated rapid effects on prostate cancer that had metastasized to bone, according to a study by researchers at the University of Michigan Comprehensive Cancer Center.
About two-thirds of patients treated with the drug showed improvements on their bone scans, with 12% achieving complete resolution of uptake on the scans. Bone scans assess the degree to which cancer is present in the bone; improvements on these scans suggest a response to therapy.
Cabozantinib (Cometriq) was approved by the FDA for the treatment of progressive metastatic medullary thyroid cancer in November 2012. It is not indicated for the treatment of prostate cancer.
According to the researchers, cabozantinib targets two important pathways linked to the growth and spread of prostate cancer. The drug had the most effect on tumors that had spread to bone, which is the major site where prostate cancer spreads. These tumors are typically challenging to treat once they become resistant to hormone-based therapies.
In addition to the improvements seen on bone scans, 67% of patients with bone pain reported an improvement in pain control, and 56% of patients decreased the use of or eliminated narcotic painkillers after treatment with cabozantinib. The results were published in the Journal of Clinical Oncology.
The new study enrolled 171 men with prostate cancer whose tumors no longer responded to hormone-based therapies. All of the patients were treated with cabozantinib for 12 weeks. At that point, they were randomly assigned to receive continued cabozantinib or placebo. The randomization was stopped early, however, because of the significant effects of cabozantinib seen on bone scans, and because patients receiving placebo progressed more quickly than did those that remained on the study drug.
Among the 31 patients who underwent randomization, cancer progressed after a median period of 23.9 weeks in patients treated with cabozantinib, compared with a median period of 5.9 weeks in placebo-treated patients.
According to the American Cancer Society, 241,740 American men will be diagnosed with prostate cancer in 2012, and 28,170 will die from the disease.