ASCO GU 2019: Skeletal Related Events in CTRIAL-IE 13-21: Radium-223 in Combination with Enzalutamide for Patients with mCRPC
The CTRIAL-IE 13-21 is a multi-center, open-label, single arm phase 2 study investigating the combination of Radium-223 and enzalutamide in mCRPC patient who progressed on androgen deprivation therapy (ADT). Prior treatment with docetaxel and bone health agents such as zolendronic acid were allowed within the study. Skeletal events were defined as pathologic fractures, spinal cord compression, necessity for external beam radiation (EBRT).
From 2015-2017 45 patients were enrolled in Ireland. The median age was 68 years (IQR 51-79). The majority of patients had ECOG performance status 0 or 1 (97.7%). Forty-two patients (93.3%) received all 6 cycles of combination therapy and 18 patients (40%) remain on enzalutamide alone at a median follow-up of 13.5 months.
Overall, 6 (13.3%) patients developed skeletal related events (SREs) including pathologic fracture (n=4), spinal cord compression (n=2), and necessity for EBRT (n=3). The average time from starting Radium-223 to development of SRE was 615 days. An unplanned retrospective analysis of the data was performed showing that 11 (24.4%) patients developed asymptomatic insufficiency fractures.
In conclusion, with the combination of Radium-223 and enzalutamide, there was no significant difference in SREs. In a separate, unplanned retrospective analysis of the data, there was a higher incidence of asymptomatic insufficiency fractures in this cohort of patients.
Presented by: John Greene, Dublin, Ireland
Written by: Selma Masic, MD, Urologic Oncology Fellow (SUO), Fox Chase Cancer Center, Philadelphia, PA. Twitter:@selmasic at the 2019 American Society of Clinical Oncology Genitourinary Cancers Symposium, (ASCO GU) #GU19, February 14-16, 2019 - San Francisco, CA