Dr. George on the Use of Radium-223 in Prostate Cancer

Daniel J. George, MD, professor of medicine and surgery, member, Duke Cancer Institute, discusses the use of radium-223 dichloride (Xofigo) in prostate cancer.

Radium-223 operates through a novel mechanism and has shown a reduction in the risk of progression or death of approximately 30% versus placebo in patients with metastatic castrate-resistant prostate cancer. Although the drug has shown a benefit in overall survival in a historically difficult-to-treat patient population, it has not been shown to affect prostate-specific antigen response or imaging response. As such, it has been difficult to employ in practice, says George.

Moreover, data from the phase III ERA-223 trial, which were presented at the 2018 ESMO Congress, pointed to the added complication of risk of fractures. In the trial, chemotherapy-naïve patients with mCRPC received abiraterone acetate (Zytiga), prednisone, and radium-223, or abiraterone and prednisone alone. Patients who received radium-223 had a higher rate of fractures than those who received abiraterone and prednisone alone. This was a new finding, says George, suggesting a potentially toxic synergy between abiraterone, prednisone, and radium-223 in a less heavily pretreated patient population. Now, there is a warning against the use of radium-223 in combination with abiraterone. However, because bone metastases lead to increased risk of mortality, George states that radium-223 can be used as monotherapy to lessen the burden of metastatic disease.