ASCO GU 2018: Overall Survival of Patients with Metastatic Prostate Cancer Starting ADT with Degarelix, A Gonadotropin-releasing Hormone Antagonist

San Francisco, CA (UroToday.com) Dr. Stephen Freedland and colleagues presented their results assessing overall survival (OS) among men with metastatic prostate cancer starting an ADT regimen with the gonadotropin-releasing hormone (GnRH) antagonist degarelix at today’s prostate cancer poster session at GU ASCO. Morbidity and mortality amongst patients diagnosed with metastatic prostate cancer remains high and ADT continues to remain the mainstay of hormonal treatment for these patients. Degarelix has a fast and profound onset of action and compares favorably with GnRH agonists in terms of progression-free survival (PFS) and OS during the first year of treatment [1]. The objective of this study was to assess longer term survival data among patients using degarelix with very advanced disease.

For this study, data on 519 patients with metastatic prostate cancer treated with degarelix from 17 controlled and uncontrolled trials were retrieved from a study repository. These patients all had metastatic disease and a PSA > 50 ng/mL treated with degarelix. The outcomes assessed were OS and PFS. Additionally, possible selection bias over time was also estimated. A Cox regression analysis was used to assess predictors of survival outcomes. Among these 519 patients meeting inclusion criteria, the median age was 71 years (IQR 65-77) and median PSA was 256 ng/mL (IQR 100-971). Survival at 36 months was 83% for patients with baseline PSA > 50 to < 200 ng/mL (n=233) and 72% for patients with baseline PSA > 200 ng/mL (n=286). The corresponding numbers for PSA-PFS at 36 months were 29% and 15%, respectively. A delayed separation of Kaplan-Meier estimates was observed between the PSA > 50 to < 200 ng/mL and > 200 ng/mL groups: 6 months for PSA-PFS and 12 months for survival. On Cox regression analysis, there was no significant effect of age (p = 0.20) or BMI (p = 0.33) on survival outcomes. The data suggest some selection bias over time in the most advanced patients.

Dr. Freedland concluded that 77% of patients with metastatic disease and PSA > 50 ng/mL who start degarelix treatment are alive after an observation period of 36 months. He cautions however that this is an analysis of uncontrolled data and as such a comparative randomized approach is required to allow potential comparison with other treatments.

Speaker: Stephen Freedland, Cedars-Sinai Medical Center, Los Angeles, CA

Co-Authors: Per Settergren Sørensen, Bo-Eric Persson

Written by: Zachary Klaassen, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre, Twitter:@zklaassen_md at the 2018 American Society of Clinical Oncology Genitourinary (ASCO GU) Cancers Symposium, February 8-10, 2018 - San Francisco, CA

References:
1. Tombal B, Miller K, Boccon-Gibod L, et al. Additional analysis of secondary end point of biochemical recurrence rate in a phase 3 trial (CS21) comparing degarelix 80 mg versus leuprolide in prostate cancer patients segmented by baseline characteristics. Eur Urol 2010;57(5):836-842.
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