Dr Morgans on Enzalutamide Plus Radium-223 in mCRPC

“We saw that both rPFS and OS were improved with the addition of radium-223 to enzalutamide when compared with the enzalutamide control arm.”

Alicia Morgans, MD, MPH, a genitourinary medical oncologist, medical director of the Survivorship Program at Dana-Farber Cancer Institute, and associate professor of medicine at Harvard Medical School, discussed findings from the phase 3 PEACE-3 trial (NCT02194842), which evaluated enzalutamide (Xtandi) in combination with radium-223 (Xofigo) for the treatment of patients with metastatic castration-resistant prostate cancer (mCRPC).

Updated findings from PEACE-3 published in Annals of Oncology demonstrated that patients who received the combination (n = 222) achieved a median radiographic progression-free survival (rPFS) of 19.4 months (96% CI, 17.1-25.3) vs 16.4 months (95% CI, 13.8-19.2) among those treated with enzalutamide monotherapy (n = 224; HR, 0.69; 95% CI, 0.54-0.87; P = .0009). Additionally, the median overall survival (OS) was 42.3 months (95% CI, 36.8-49.1) compared with 35.0 months (95% CI, 28.8-38.9), respectively.

The estimated 12- and 24-month rPFS rates in the investigational arm were 69.2% (95% CI, 62.5%-75.0%) and 45.1% (95% CI 37.7%-52.1%), respectively; these respective rates were 60.5% (95% CI, 53.6%-66.8%) and 35.9% (95% CI, 29.1%-2.8%) in the control arm.

Morgans noted that the study included patients who had received androgen deprivation therapy (ADT) or ADT plus docetaxel in the metastatic setting. These findings were significant because both enzalutamide and radium-223 are already available options for these patients, she added. Enzalutamide has been a strong standard of care (SOC) in this setting for several years and remains a high bar to clear in a clinical trial, she said.

The addition of radium-223 to enzalutamide led to both an rPFS and OS benefit in terms of, which was notable, Morgans explained. Based on these results, radium-223 plus enzalutamide should be considered a SOC therapy for patients with mCRPC, especially in those with bone-predominant metastatic disease or lymph node involvement, Morgans concluded.