LBA02-09 EMBARK: A Phase 3 Randomized Study of Enzalutamide or Placebo Plus Leuprolide Acetate and Enzalutamide Monotherapy in High-risk Biochemically Recurrent Prostate Cancer

Volume 209, Supplement 4, Page e1190: The abstract text is as given below. This erratum also includes the additional disclosure, conflict of interest, and acknowledgments that were not included in the original publication. The online and PDF versions of the article have been updated. INTRODUCTION AND OBJECTIVE: Within 10 years following definitive therapy for prostate cancer, ∼20-50% of patients (pts) experience biochemical recurrence (BCR) characterized by rising prostate-specific antigen (PSA) levels. Pts with high-risk BCR have an increased risk of mortality and improved therapies are needed. The objective of EMBARK was to evaluate the efficacy and safety of enzalutamide (enza) + androgen deprivation therapy (ADT) and enza monotherapy (mono) in pts with high-risk BCR. METHODS: EMBARK is a randomized, phase 3 study of pts with BCR considered high-risk: PSA doubling time ≤9 months and PSA ≥2 ng/mL above nadir post-radiotherapy (RT) or ≥1 ng/mL after radical prostatectomy (RP) ± postoperative RT. Pts were randomized (1:1:1) to enza 160 mg/day + leuprolide acetate (LA) (double-blind), placebo (pbo) + LA (double-blind), or enza mono (open-label). LA 22.5 mg was administered every 12 weeks. If the PSA at week 36 was <0.2 ng/mL, therapy was stopped at week 37 and restarted when PSA was ≥2 ng/mL for pts with primary RP, and ≥5 ng/mL for pts without RP. The primary endpoint, determined by blinded, independent central review (BICR), was metastasis-free survival (MFS) with enza + LA vs pbo + LA. Key secondary endpoints were MFS of enza mono vs pbo + LA, time to PSA progression, time to antineoplastic therapy, and overall survival (OS) of enza + LA or enza mono vs pbo + LA. RESULTS: 1068 pts were randomized into the study (enza + LA, n=355; pbo + LA, n=358; enza mono, n=355). After median follow-up of 60.7 months, per BICR, MFS for enza + LA (HR 0.42; 95% CI 0.30-0.61; p<0.0001) and enza mono (HR 0.63; 95% CI 0.46-0.87; p=0.0049) were statistically superior to pbo + LA. Statistically significant improvements were also observed in risk of PSA progression (enza + LA: HR 0.07; 95% CI, 0.03-0.14; enza mono: HR 0.33; 95% CI, 0.23-0.49; both p<0.0001) and time to first use of new antineoplastic therapy (enza + LA: HR 0.36; 95% CI, 0.26-0.49; enza mono: HR 0.54; 95% CI, 0.41-0.71; both p<0.0001). Interim OS data trended in favor enza + LA (HR 0.59; 95% CI, 0.38-0.91; p=0.0153, did not cross interim efficacy boundary) and enza mono (HR 0.78; 95% CI, 0.52-1.17; p=0.2304). Fatigue and hot flash were the most common adverse events; no new safety signals were observed. CONCLUSIONS: In pts with high-risk BCR, enza + ADT and enza mono demonstrated a statistically significant and clinically meaningful improvement in MFS vs pbo + ADT. The safety profile of enza was consistent with results from previous clinical studies. CLINICAL TRIAL REGISTRATION NUMBER: NCT02319837. SOURCE OF FUNDING: Pfizer Inc. and Astellas Pharma Inc.Conflict of Interest and Disclosure Statement:Neal D. Shore reports grant support and consulting fees from AbbVie, Amgen, Astellas Pharma Inc., AstraZeneca, Bayer, Clovis Oncology, Dendreon Pharmaceuticals LLC, Ferring Pharmaceuticals, GenesisCare, Janssen Oncology, Merck, Myovant Sciences, Pfizer Inc., Sanofi-Genzyme, and Tolmar Pharmaceuticals, Inc. Murilo de Almeida Luz reports receiving speaker honoraria from Astellas Pharma Inc., Bayer, Janssen, Merck Sharp & Dohme, and Pfizer Inc.; being an advisory board member for Astellas Pharma Inc., Bayer, and Janssen; sponsored research from Bayer, Bristol Myers Squibb, Ferring Pharmaceuticals, GlaxoSmithKline, Janssen, and Roche; receiving travel expenses from AstraZeneca, Bayer, Janssen, and Pfizer Inc. Ugo De Giorgi reports serving as a consultant for Janssen, Astellas Pharma Inc., Sanofi, Bayer, Pfizer Inc., Bristol Myers Squibb, Novartis, Ipsen, and Merck Sharp & Dohme. Martin Gleave reports stock or ownership interest in OncoGenex Technologies Inc., Sustained Therapeutics Inc., and Sikta Biopharma; is a consultant to Astellas Pharma Inc., AstraZeneca, Bayer, Genova Diagnostics (GDx), Janssen, Pfizer Inc., Roche, Sanofi, and TerSera Therapeutics LLC; and holds patents for OGX-011, OGX-427, ST-CP, and ST-POP. Geoffrey T. Gotto reports receiving honoraria from Amgen, Astellas Pharma Inc., Bayer, Ferring Pharmaceuticals, Janssen, and Merck; being a consultant or advisory board member for Amgen, Astellas Pharma Inc., Bayer, Janssen, and Merck; providing expert testimony for Janssen; and receiving support for travel, accommodation, and expenses from Janssen. Gabriel P. Haas reports being an employee of and shareholder in Astellas Pharma Inc. Miguel Ramirez-Backhaus reports serving as a consultant or advisory board member for Astellas Pharma Inc., Bayer, Janssen, and Karl Storz; receiving speaker honoraria from Astellas Pharma Inc., Bayer, Janssen, and GP Pharm. Antti Rannikko reports being a board member for the Ida Montin Foundation, and Orion Research Foundation; being an advisory board member for Bayer, Janssen, and Orion Pharma; being a stockholder and clinical advisor for Aqsens Health; being a clinical investigator for Astellas Pharma Inc., Bayer, Janssen, Orion Pharma, and RhoVac AB; and receiving competitive state research funding from HUS Helsinki University Hospital, Finnish Cancer Organizations, and the Jane and Aatos Erkko Foundation. Jamal Tazari, Yiyun Tang, and Fabian Zohren are employees of and shareholders in Pfizer Inc. Swetha Sridharan reports no conflicts of interest. Jennifer Sugg is an employee of Astellas Pharma Inc., and a shareholder in AstraZeneca. Ronald F. Tutrone, Jr. reports being an advisory board member for Bayer; and receiving speaker honoraria from Astellas Pharma Inc., Exosome Diagnostics, Inc., Myovant Sciences, and Pfizer Inc. Balaji Venugopal reports receiving honoraria from Bristol Myers Squibb, Eisai Co., Ltd, EUSA Pharma, Ipsen, Janssen, and Merck; being a consultant or advisory board member for Janssen, Merck Sharp & Dohme Oncology, and Pfizer Inc./EMD Serono; and receiving support for travel, accommodation, and expenses from EUSA Pharma, and Ipsen. Arnauld Villers reports receiving research grants from Astellas Pharma Inc., Ferring Pharmaceuticals, Ipsen, and Janssen. Henry H. Woo reports being an advisory board member for Astellas Pharma Inc., Bayer, Boston Scientific Corporation, and Mundipharma International Ltd; and reports receiving speaker honoraria from AbbVie, Astellas Pharma Inc., Boston Scientific Corporation, and Janssen. Stephen J. Freedland reports being a consultant for Astellas Pharma Inc., AstraZeneca, Bayer, Dendreon Pharmaceuticals LLC, Janssen, Merck, Myovant Sciences, Pfizer Inc., and Sanofi. ACKNOWLEDGMENTS: The authors thank all the patients, their families, and the investigators and investigational site members involved in this study.Editorial Acknowledgement:Medical writing and editorial support was provided by Julie B. Stimmel, PhD, Sinead Stewart, and Rosie Henderson, of Onyx (a Prime Global Agency), funded by Pfizer, Inc. and Astellas Pharma Inc., the co-developers of enzalutamide.Submission Category:prostate cancer.Sub-category:Advanced (including drug therapy).