Posted: Tuesday, November 15, 2022
Phuoc T. Tran, MD, PhD, of the University of Maryland School of Medicine, Baltimore, and colleagues investigated whether enzalutamide treatment could improve freedom from prostate-specific antigen (PSA) progression when combined with salvage radiation therapy in patients with recurrent prostate cancer after radical prostatectomy. Presented during the 2022 American Society for Radiation Oncology (ASTRO) Annual Meeting (Abstract 159), these findings suggest this therapeutic strategy may prove to be effective in this patient population.
“[Salvage radiation therapy] plus [enzalutamide] monotherapy for men with PSA-recurrent high-risk prostate cancer following [radical prostatectomy] is safe and delays PSA progression relative to [salvage radiotherapy alone],” concluded the investigators. However, “the impact of [enzalutamide] on distant metastasis or survival is unknown at this time.”
The study authors focused on 86 men diagnosed with biochemically recurrent prostate cancer after radical prostatectomy in this phase II, double-blind, multicenter study. Participants were randomly assigned on a 1:1 basis to receive either placebo or enzalutamide once daily for 6 months, followed by external-beam radiotherapy administered to the prostate bed.
At a median follow-up of 34 months, the median PSA level before salvage radiation therapy was 0.3 ng/mL. Extraprostatic disease (pT3) was detected in 65% of patients, 50% had positive surgical margins, and 45% had Gleason grade group 4 disease or higher. Trial arms and patient demographics were well balanced.
Patients receiving enzalutamide appeared to have a significantly improved freedom from PSA progression compared with placebo, with 2-year rates of 87.1% and 68.1%, respectively (hazard ratio [HR] = 0.40; P = .026). Additionally, subgroup analyses revealed a differential benefit of enzalutamide in men with pT3 disease (HR = 0.19) versus those with pT2 disease (HR = 1.29; P = .031). Of note, the most common adverse events with the combination therapy were grade 1 to 2 urinary frequency and fatigue.
Disclosure: Dr. Tran’s full disclosures are available at plan.core-apps.com.