Last year on this blog we posted important warnings about using abiraterone (Zytiga) in combination with Xofigo (Radium 223). The warnings were around a finding from a clinical trial (ERA 223) that men with prostate cancer who used both Zytiga and Xofigo in combination were found to be at an increased risk of developing severe bone fractures when compared to men who did not receive both of these treatments in combination (the control group).
These findings led to the FDA indicating that the use of Xofigo in combination with abiraterone (Zytiga) is contra-indicated. Additionally, the European Medicines Agency (EMA) recommended that the use of Xofigo (Radium-223) be restricted so that Xofigo can only be used after two other treatments have been taken; when other therapies cannot be used and not in combination with other 2nd line hormone therapies.
There has been some exciting follow-up subgroup analysis that has indicated that the men who had Xofigo and Radium-223 in combination and suffered these bad fractures tended to be men who were not also on bone-targeted therapies like Zometa or Xgeva. The men who were on these bone-targeted therapies did experience an increased risk for these fractures when compared to the control group.
Does this finding have any immediate clinical value for us?
Listen to an interview between Drs. Philip Koo and Charles J. Ryan discuss this finding.