ASCO GU 2018: Survival Outcomes of Pre-Metastatic Castration-Resistant Prostate Cancer and the Burden of Developing Metastasis: A Systematic Literature Review

San Francisco, CA ( Medical castration, or more rarely surgical castration, has become the mainstay of therapy for metastatic prostate cancer following definitive primary therapy or for de novo metastatic disease. However, unfortunately, all men eventually develop resistance and progress. While the therapeutic options continue to grow for men who do progress, there remains a disease-space that has yet to be adequately addressed. Specifically, men who demonstrate PSA progression following castration but who do not have evidence of metastatic disease (cM0 CRPC), currently have no approved therapeutic options.

In this study, the authors provide a systematic literature review, but not a meta-analysis, of the cM0 CRPC disease space. After exclusions, 16 clinical articles, 12 economic articles and 20 guidelines reviews. Some of their key findings:

•  Median overall survival for cM0 CRPC patients ranged from 44 to 74 months
•  Median progression-free survival from 9 to 22 months
   o None of the studies link PFS to OS
• Median metastasis-free survival from 16 to 53 months
   o One study linked MFS as a surrogate for OS
• Most common form of metastasis was bone metastasis, which was associated with an increased risk of skeletal-related events (SREs)
• Quality-of-life was widely reported to decrease upon metastasis, driven by increased pain and SREs
• Higher healthcare costs associated with metastatic CRPC were attributable to physician visits and treating bone-metastasis-related complications.

The authors make a case for the importance of therapies in this space, as it could delay the onset of metastasis and thereby lead to economic benefits for healthcare delivery systems.

Indeed, at GU ASCO this year, two major Phase III studies assessing enzalutamide and apalutamide for this very disease space are reporting final results. With promising oncologic outcomes, they may be the beginning of a trend to earlier initiation of systemic therapies for cM0 CRPC.

Speaker: Neal Shore, MD

Co-Authors: Gershwinder Rai, Karim Fizazi, Laura Wilson, Lin Zhan

Institution(s): Carolina Urologic Research Center, Myrtle Beach, SC; QuintilesIMS, Reading, United Kingdom; Gustave Roussy Institute of Oncology, University of Paris-Sud, Villejuif, France; Bayer HealthCare Pharmaceuticals Inc., Whippany, NJ

Written by: Thenappan Chandrasekar, MD, Clinical Fellow, University of Toronto, Twitter: @tchandra_uromd at the 2018 American Society of Clinical Oncology Genitourinary (ASCO GU) Cancers Symposium, February 8-10, 2018 - San Francisco, CA