Dr Saad on Baseline Patient Characteristics From the Phase 3 PEACE-3 Trial in mCRPC

Fred Saad, CQ, MD, FRCS, FCAHS, director of prostate cancer research at Montreal Cancer Institute, as well as a full professor in the Department of Surgery and a uro-oncologist in the Department of Urology at the University of Montreal Hospital Center, discussed baseline patient characteristics and treatment patterns from the phase 3 PEACE-3 trial (NCT02194842), which evaluated the combination of radium-223 dichloride (Xofigo) and enzalutamide (Xtandi) in patients with metastatic castration-resistant prostate cancer (mCRPC) and bone-predominant disease.

The PEACE-3 study enrolled a real-world population of patients with advanced disease, characterized by an older median age and a disease distribution more reflective of clinical practice. The median age at enrollment was 73 years, which Saad noted was slightly higher than that typically seen in registration trials. This aligns more closely with the patient population encountered in routine practice. In the study, approximately 80% of patients had bone-only metastases, whereas approximately 20% had limited extramedullary involvement, primarily small lymph node lesions. This inclusion of patients with minimal soft-tissue disease allowed for a more comprehensive assessment of treatment outcomes across a broader metastatic spectrum, he explained.

Notably, 67% of patients received at least 5 cycles of radium-223. According to Saad, this finding underscores the improved clinical integration of the therapy and supports the importance of maintaining adequate treatment duration to achieve optimal outcomes. He emphasized that radium-223 functions as a cumulative radiopharmaceutical, and its efficacy is dependent on delivering the full course of 5 to 6 cycles. Patients who discontinue treatment early, often due to deteriorating performance status or symptomatic progression, are less likely to derive the full therapeutic benefit, he added.

These treatment completion rates are reassuring, as they suggest a growing clinical understanding of how to effectively sequence and manage radium-223 in combination with next-generation androgen receptor inhibitors, Saad explained. Initiating therapy before patients become excessively symptomatic may allow for completion of the recommended dosing schedule, thereby optimizing both efficacy and safety outcomes, he concluded.