San Francisco, CA USA (UroToday.com). Among men with metastatic castration-resistant prostate cancer (mCRPC) who were initiated on enzalutamide or bicalutamide treatment, more central nervous system (CNS) events occurred with enzalutamide, even when investigators controlled for metastatic status, in a first-time “real world” examination of this issue.1 (The phase II TERRAIN study previously demonstrated a statistically significant increase in progression-free survival with enzalutamide versus bicalutamide in men with mCRPC.)2
These findings were presented at the 2016 ASCO Genitourinary Cancers Symposium, January 7-9, in San Francisco.
For this investigation, Dr. Ajay Behl and colleagues from Janssen Scientific Affairs and the Lombardi Comprehensive Cancer Center, examined retrospective claims from the Truven Health MarketScan database, to identify CNS occurrences. They identified patients with one or more claim(s) for enzalutamide or bicalutamide after September 1, 2012; patients with greater than 6 months of continuous eligibility prior to the index date (baseline period); and patients with no use of either agent prior to the index date.
Patients were followed until December 2014 or until they were lost to follow-up. (Patients were excluded if they had a CNS condition or received another cancer diagnosis during the baseline period.) CNS conditions were described as a diagnosis for amnesia or memory impairment, anxiety, ataxia, cognitive disorders, confusion, convulsions, disturbances in attention, dizziness, falls, fatigue or asthenia, hallucinations, headaches, insomnia, pain, paresthesias, seizures, weakness, or other CNS disorders.
Kaplan-Meier (KM) survival curves were used to compare the KM rates of developing any CNS condition between patients who initiated enzalutamide versus patients who initiated bicalutamide. A subgroup analysis of patients with metastatic disease was conducted.
The study confirmed that rates of CNS events were significantly higher among men with mCRPC who initiated therapy with enzalutamide as compared with bicalutamide, even after controlling for metastatic status.
Written by: Barbara Jones
1. Behl A, Ellis L, Pilon D, et al. Oberservation of CNS events in real-world use of enzalutamide (ENZ) and bicalutamide (BIC). At: http://meetinglibrary.asco.org/print/2132461
2. Baskin-Bey ES, Shore ND, Barber K, et al. TERRAIN: A randomized, double-blind, phase II study comparing MDV3100 with bicalutamide (Bic) in men with metastatic castrate-resistant prostate cancer (CRPC). J Clin Oncol 30, 2012 (suppl; abstr TPS4698^)