Radium-223 Approved For Advanced Prostate Cancer

Richard Pazdur, MD

The FDA approved radium RA 223 dichloride (Xofigo) for the treatment of symptomatic metastatic castration-resistant prostate cancer (mCRPC) that has spread to the bones but not to any other organs.

The alpha radiation-emitting drug, also known as radium-223 and formerly known as Alpharadin, was granted priority review in February. Though an action date had been set for August, the FDA approved the drug through its expedited priority review program, which is designed for drugs that appear to be safe and effective in managing patients for whom no reasonable alternative therapies exist.

“Xofigo binds with minerals in the bone to deliver radiation directly to bone tumors, limiting the damage to the surrounding normal tissues,” said Richard Pazdur, MD, director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research, in a statement. “Xofigo is the second prostate cancer drug approved by the FDA in the past year that demonstrates an ability to extend the survival of men with metastatic prostate cancer.”

Radium-223 is an injectable therapeutic alpha particle-emitting drug designed to have an antitumor effect on bone metastases in patients with mCRPC.

The approval was based on the results of the ALSYMPCA trial, a phase III, double-blind, randomized, multinational study designed to compare radium-223 with a placebo and best standard care in patients with CRPC and at least two bone metastases. According to updated results presented at the 2012 American Society of Clinical Oncology (ASCO) Annual Meeting, radium-223 significantly improved overall survival (OS), with patients in the radium-223 arm of the study experiencing a median OS of 14.9 months compared with 11.3 months in the placebo arm (hazard ratio [HR] = 0.695; 95% CI, 0.581-0.832; P = .00007). Additionally, the time to the first skeletal-related event was a median of 15.6 months in the radium-223 arm of the study, a significant prolongation over the 9.8 months in the placebo arm (HR = 0.658; 95% CI, 0.522-0.830; P = .00037).

According to the FDA, the most common side effects reported during clinical trials were nausea, diarrhea, vomiting and swelling of the leg, ankle, or foot. The most common abnormalities detected in blood tests included anemia, lymphocytopenia, leukopenia, thrombocytopenia, and neutropenia.

Approximately 238,590 men will be diagnosed with prostate cancer and 29,720 will die from the disease in 2013, according to the National Cancer Institute. Prostate cancer metastasizes to the bone in approximated 90% of advanced cases of the disease.

The drug is marketed by Bayer Pharmaceuticals, based in Wayne, New Jersey.

Parker C, Nilsson S, Heinrich D, et al. Updated analysis of the phase III, double-blind, randomized, multinational study of radium-223 chloride in castration-resistant prostate cancer with bone metastases (ALSYMPCA). J Clin Oncol. 2012;30(suppl; abstr LBA4512).