Preventing Skeletal Fractures in Patients Treated for Metastatic Prostate Cancer
Posted: Monday, August 5, 2019
Men with asymptomatic metastatic castration resistant prostate cancer have an increased risk of skeletal fractures when treated with enzalutamide and radium Ra 223 dichloride (Ra223). According to a new study by Bertrand F. Tombal, MD, PhD, of the Université Catholique de Louvain in Belgium, and colleagues, it may be possible to “almost abolish” this risk by continuous administration of bone-protective agents at least 6 weeks before the first injection of Ra223. The investigators presented their work at the 2019 American Society of Clinical Oncology (ASCO) Annual Meeting and published it in the Journal of Clinical Oncology.
The researchers analyzed patients enrolled in the phase III EORTC 1333/PEACE phase III trial, which compared enzalutamide and a combination of enzalutamide and Ra223 in patients with metastatic castration-resistant prostate cancer. In April 2018, the trial was unblinded and amended to ensure that all patients were started on a bone-protecting agent such as zoledronic acid or denosumab. As of January 2019, 146 patients were treated in the study.
Of the patients treated with enzalutamide and Ra223 together, 54.2% did not receive a bone-protecting agent, whereas 51.4% of those treated with enzalutamide alone did not receive one. At the time of randomization, 27.8% of patients in the combination arm and 21.6% of patients in the single-treatment arm used bone-protecting agents. After the amendment to the study, 18% of patients in the Ra223 combination arm and 27% of patients in the enzalutamide arm began using bone-protecting agents.
For patients not given bone protection, fracture rates were 33% and 13% for the enzalutamide/Ra223 arm and enzalutamide-alone arm, respectively. Patients who were given bone protection had fracture rates of 3% and 0% in the combination and enzalutamide arms.
Disclosure: The study authors’ disclosure information may be found at ascopubs.org.