Radium-223 (Xofigo) is a drug for men with castrate resistant metastatic prostate cancer (mCRCP) who have multiple bone metastases. Radium-223 selectively targets bone metastases by mimicking calcium, which is attracted to the bone, especially to the fast growing areas of the tumor in the bone. It emits an alpha-emitting dose of radiation, which is mostly contained in the tumor due to the low spread of alpha waves).

The current FDA approval for Radium-223 is for one course of 6 injections. Men have been asking if it is possible to have a re-treatment of Radium-223 once the disease has progressed after having had the approved dose. In research discussed at the ASCO GU conference in San Francisco it was disclosed that a second round of Radium-223 is well tolerated and continues to control disease progression in bone.

The conclusion was based on a study of 44 men with mCRPC who completed an initial 6-injection course of treatment (the FDA approved dose) of radium-223. The research team, led by Oliver Sartor, MD, of the Tulane Cancer Center in New Orleans, found that radiographic bone progression with radium-223 re-treatment was rare, with most disease progression occurring in soft tissue (or not in bone).

Of the 44 men, 29 (66%) completed re-treatment with all 6 injections. The median time from the end of initial radium-223 treatment was 6 months. Thirty-two men (73%) had failed prior treatment with newer hormo