Radium-223 Gets Early FDA Nod for Bone Mets in Castration-Resistant Prostate Cancer

Radium-223 dichloride (Xofigo) received US Food and Drug Administration (FDA) approval for the treatment of symptomatic metastatic castration-resistant prostate cancer that has metastasized to the bone but no other organs. The approval came 3 months ahead of schedule under the FDA’s priority review program, which provides for expedited review of drugs that fill a need where no other medical therapy exists.

Osteoplastic metastasis of prostate cancer

The agent is the first alpha particle-emitting radioactive therapeutic agent approved by the FDA.

“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.

The drug gained its approval based on results of the ALSYMPCA trial, a phase III trial that evaluated 809 men with metastatic castration-resistant prostate cancer that had spread to the bone. The patients were randomly assigned to treatment with radium-223 dichloride or placebo plus best standard of care. Patients received up to six intravenous administrations of radium-223 dichloride or placebo separated by an interval of 4 weeks.

Results taken from an interim analysis showed that patients receiving radium-223 dichloride had a median survival of 14 months compared with 11.2 months for men receiving placebo. An exploratory updated analysis conducted later in the trial confirmed the drug’s ability to extend overall survival.

According to the FDA, the most commonly occurring adverse events were nausea, diarrhea, vomiting and swelling of the leg, ankle, or foot.

“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,” Dr. Pazdur said.

In August 2012, the FDA approved enzalutamide (Xtandi) to treat men with metastatic castration-resistant prostate cancer that has spread or recurred, even with medical or surgical therapy to minimize testosterone. Enzalutamide is approved for patients who have previously been treated with the chemotherapy docetaxel.