Steven E. Finkelstein, MD, the national director of Translational Research at 21st Century Oncology, discusses the May 2013 approval of the alpha radiation emitting agent radium-223 dichloride (Xofigo).

Radium-223, which was granted priority review in February before being approved, treats symptomatic metastatic castrate-resistant prostate cancer (mCRPC) in patients where the disease has spread to the bones but no other organs, Frinkelstein says.

This agent is interesting, Frinkelstein says, because it limits the damage to the surrounding normal tissue by binding exclusively with minerals in the bone to deliver the radiation. However, the most important attribute of radium-223 is that it extends survival for men with mCRPC, notes Finkelstein.

The approval of the injectable therapeutic alpha particle emitting drug was based on the results of the phase III ALSYMPCA trial that compared radium-223 with a placebo in patients with mCRPC who had at least two bone metastases, Frinkelstein says. The most common side effects that were reported during the clinical trial were nausea, diarrhea, vomiting and swelling of the ankle, leg or foot. The most common hematologic laboratory abnormalities included anemia, lymphocytopenia, leucopenia, thrombocytopenia and neutropenia.