Efficacy and Safety of Pembrolizumab (MK-3475) Plus Enzalutamide Plus Androgen Deprivation Therapy (ADT) Versus Placebo Plus Enzalutamide Plus ADT in Participants With Metastatic Hormone-Sensitive Prostate Cancer (mHSPC) (MK-3475-991/KEYNOTE-991)
Metastatic Hormone-Sensitive Prostate Cancer

About this trial
This is an interventional treatment trial for Metastatic Hormone-Sensitive Prostate Cancer focused on measuring Programmed Cell Death-1 (PD1, PD-1),, Programmed Death-Ligand 1 (PDL1, PD-L1)
Eligibility Criteria
Inclusion Criteria:
- Male participants with histologically- or cytologically-confirmed adenocarcinoma of the prostate without small cell histology
- Has metastatic disease assessed by investigator and verified by BICR by either ≥2 bone lesions on bone scan and/or visceral disease by computed tomography/magnetic resonance imaging (CT/MRI)
- Willing to maintain continuous ADT with a LHRH agonists or antagonists during study treatment or have a history of bilateral orchiectomy
- Has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 assessed within 10 days of randomization
- Participants receiving bone resorptive therapy (including, but not limited to, bisphosphonate or denosumab) must have been on stable doses prior to randomization
- Has adequate organ function
- Has provided newly obtained core or excisional biopsy (obtained within 12 months of screening) from soft tissue not previously irradiated (samples from tumors progressing in a prior site of radiation are allowed). Participants with bone only or bone predominant disease may provide a bone biopsy sample
- Male participants must agree to the following during the intervention period and for at least 120 days after the last dose of study intervention: Refrain from donating sperm PLUS either be abstinent from heterosexual intercourse and agree to remain abstinent OR agree to use contraception, unless confirmed to be azoospermic
- Male participants must agree to use male condom when engaging in any activity that allows for passage of ejaculate to another person of any sex
Exclusion Criteria:
- Has a known additional malignancy that is progressing or has required active treatment in the last 3 years
- Has an active autoimmune disease that has required systemic treatment in past 2 years
- Has a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy
- Has undergone major surgery including local prostate intervention (excluding prostate biopsy) within 28 days prior to randomization and not recovered adequately from the toxicities and/or complications
- Has a gastrointestinal disorder affecting absorption or is unable to swallow tablets/capsules
- Has an active infection (including tuberculosis) requiring systemic therapy
- Has a history of (non-infectious) pneumonitis that required steroids or has current pneumonitis
- Has known active human immunodeficiency virus (HIV), hepatitis B virus (HBV) or hepatitis C virus (HCV) infection
- Has known or suspected central nervous system (CNS) metastases and/or carcinomatous meningitis
- Has a history of seizure or any condition that may predispose to seizure
- Has a history of loss of consciousness within 12 months of screening
- Has had myocardial infarction or uncontrolled angina within 6 months prior to randomization, or has New York Heart Association class III or IV congestive heart failure or a history of New York Heart Association class III or IV congestive heart failure
- Has hypotension (systolic blood pressure <86 millimeters of mercury [mmHg]) or uncontrolled hypertension (systolic blood pressure >170 mmHg or diastolic blood pressure >105 mmHg) at the screening visit
- Has a history of clinically significant ventricular arrhythmias
- Has hypersensitivity to pembrolizumab and/or enzalutamide and/or any of their excipients
- Has received prior ADT as neoadjuvant/adjuvant therapy for non-metastatic prostate cancer for >39 months in duration or within 9 months prior to randomization or with evidence of disease progression while receiving ADT
- Has had prior treatment with a next generation hormonal agent (eg, abiraterone, enzalutamide, apalutamide, darolutamide)
- Has received prior therapy with an anti-programmed cell death-1 (anti-PD-1), anti-programmed cell death-ligand 1 (anti-PD-L1), or anti PD-L2 agent or with an agent directed to another stimulatory or coinhibitory T-cell receptor
- Has received a live vaccine within 30 days prior to randomization
- Has a "superscan" bone scan
- Has had an allogenic tissue/solid organ transplant
- Is expecting to conceive or father children within the projected duration of the study, starting with the screening visit through 120 days after the last dose of study treatment
- Has received any prior pharmacotherapy, radiation therapy or surgery for metastatic prostate cancer with the following exceptions: - Up to 3 months of ADT or orchiectomy with or without concurrent first-generation antiandrogens, if patient was not treated with docetaxel
- May have 1 course of palliative radiation or surgical therapy to treat symptoms resulting from metastatic disease if it was administered at least 4 weeks prior to randomization
- For participants with low volume metastatic disease, may have 1 course of definitive radiotherapy if it was administered at least 4 weeks prior to randomization
- Up to 6 cycles of docetaxel therapy with final treatment administration completed within 2 months of randomization and no evidence of disease progression. In these participants up to 6 months of ADT permitted
 
Sites / Locations
- Alaska Clinical Research Center ( Site 0274)
- Providence Alaska Medical Center ( Site 0276)
- City of Hope Medical Center ( Site 0217)
- UCLA Hematology/Oncology - Santa Monica ( Site 0241)
- University of Colorado, Anschutz Cancer Pavilion ( Site 0236)
- Hartford HealthCare Medical Group ( Site 0212)
- Smilow Cancer Center at Yale-New Haven ( Site 0250)
- Sibley Memorial Hospital ( Site 0275)
- Winship Cancer Institute of Emory University ( Site 0209)
- The University of Chicago ( Site 0264)
- Springfield Clinic [Springfield, IL] ( Site 0240)
- Cotton-O'Neil Cancer Center ( Site 0228)
- The Sidney Kimmel Comprehensive Cancer Center ( Site 0204)
- St. Vincent Frontier Cancer Center-Research ( Site 0213)
- Comprehensive Cancer Centers of Nevada ( Site 0269)
- Laura and Isaac Perlmutter Cancer Center at NYU Langone Health ( Site 0270)
- Weill Cornell Medical College ( Site 0263)
- Associated Medical Professionals of NY ( Site 0251)
- Duke University ( Site 0206)
- Tri-State Urologic Services PSC, Inc. ( Site 0253)
- MidLantic Urology ( Site 0273)
- Ralph H. Johnson VA Center ( Site 0256)
- Carolina Urologic Research Center ( Site 0259)
- Urology Associates [Nashville, TN] ( Site 0233)
- Inova Health System ( Site 0205)
- Urology of Virginia ( Site 0224)
- Seattle Cancer Care Alliance ( Site 0258)
- Chris OBrien Lifehouse ( Site 0300)
- Port Macquarie Base Hospital ( Site 0301)
- Riverina Cancer Care Center ( Site 0302)
- Gallipoli Medical Research Foundation ( Site 0309)
- John Flynn Hospital & Medical Centre ( Site 0308)
- Box Hill Hospital ( Site 0304)
- Monash Health ( Site 0305)
- Peter MacCallum Cancer Centre ( Site 0306)
- Fiona Stanley Hospital ( Site 0311)
- Ordensklinikum Linz GmbH Elisabethinen ( Site 0901)
- Landeskrankenhaus Salzburg - Universitatklinikum der PMU ( Site 0900)
- Krankenhaus der Barmherzigen Brüder Wien ( Site 0904)
- Medizinische Universitaet Wien ( Site 0903)
- Oncocentro Ceara ( Site 2309)
- Instituto de Cancer e Transplante de Curitiba ICTR ( Site 2306)
- Hospital Sao Vicente de Paulo ( Site 2303)
- Hospital de Clinicas de Porto Alegre ( Site 2304)
- Clinica de Oncologia Reichow ( Site 2308)
- Fundacao Dr Amaral Carvalho ( Site 2302)
- Instituto do Cancer do Estado de Sao Paulo - ICESP ( Site 2305)
- The Ottawa Hospital ( Site 0100)
- Niagara Health System - St. Catharines ( Site 0107)
- CISSS de la Monteregie-Centre ( Site 0105)
- Centre Hospitalier de l Universite de Montreal - CHUM ( Site 0109)
- CIUSSS Ouest de l Ile - St-Mary s Hospital ( Site 0106)
- CHUQ-Univ Laval-Hotel Dieu de Quebec ( Site 0101)
- Centro Investigación del Cáncer James Lind ( Site 2401)
- IC La Serena Research ( Site 2406)
- Clinica Universidad Catolica del Maule ( Site 2407)
- Clinica Alemana ( Site 2408)
- Pontificia Universidad Catolica de Chile ( Site 2402)
- Sociedad Medica Aren y Bachero Limitada ( Site 2403)
- Oncocentro ( Site 2400)
- Peking University First Hospital ( Site 0800)
- Zhejiang Provincial People's Hospital ( Site 0809)
- The First Affiliated Hospital of Wenzhou Medical University ( Site 0834)
- Institucion Prestadora de Servicios de Salud Clinica de la Costa LTDA ( Site 2504)
- Sociedad de Oncología Y Hematología del Cesar S.A.S. ( Site 2509)
- Administradora Country SA - Clinica del Country ( Site 2507)
- Instituto Nacional de Cancerologia E.S.E ( Site 2506)
- Hemato Oncologos ( Site 2503)
- Rigshospitalet ( Site 1005)
- Herlev og Gentofte Hospital. ( Site 1004)
- Aalborg Universitetshospital ( Site 1000)
- Odense Universitetshospital ( Site 1003)
- Vejle Sygehus ( Site 1002)
- Keski-Suomen keskussairaala ( Site 1017)
- Tampereen yliopistollinen sairaala ( Site 1022)
- HYKS ( Site 1020)
- TYKS T-sairaala Syopatautien pkl ( Site 1019)
- Centre Leon-Berard ( Site 1110)
- Institut de cancérologie Strasbourg Europe (ICANS) ( Site 1114)
- CHU de Brest -Site Hopital Morvan ( Site 1103)
- Centre Georges Francois Leclerc ( Site 1112)
- CHU-Jean Minjoz ( Site 1101)
- Institut Bergonie ( Site 1104)
- Hopital Foch ( Site 1105)
- C.H.R.U. de Rennes. Hopital de Pontchaillou ( Site 1117)
- Institut Jean Godinot-Clinical Research Unit ( Site 1118)
- Centre D Oncologie de Gentilly ( Site 1107)
- Centre Bourgogne ( Site 1119)
- Hospices Civils de Lyon Centre Hospitalier Lyon Sud ( Site 1102)
- Hopital Henri Mondor ( Site 1116)
- Universitaetsklinikum Freiburg ( Site 1200)
- Klinikum der Universitaet Muenchen - Grosshadern ( Site 1210)
- Klinikum Rechts der Isar ( Site 1206)
- Klinikum Nuernberg Nord ( Site 1213)
- Staedtisches Klinikum Braunschweig gGmbH ( Site 1217)
- Universitaetsklinikum Magdeburg A.o.R. ( Site 1211)
- Universitaetsklinikum der Technischen Universitaet Dresden ( Site 1204)
- Charite Universitaetsmedizin Berlin ( Site 1201)
- Universitaetsklinikum Hamburg-Eppendorf ( Site 1212)
- Cork University Hospital ( Site 1304)
- Beaumont Hospital ( Site 1302)
- Tallaght University Hospital ( Site 1301)
- St Vincents University Hospital ( Site 1300)
- University Hospital Limerick ( Site 1305)
- University Hospital Waterford ( Site 1303)
- Rambam Medical Center ( Site 1400)
- Hadassah Ein Kerem Medical Center ( Site 1404)
- Meir Medical Center ( Site 1401)
- Rabin Medical Center ( Site 1402)
- Sourasky Medical Center ( Site 1403)
- Assaf Harofeh Medical Center ( Site 1405)
- Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori ( Site 1503)
- Istituto Clinico Humanitas Research Hospital ( Site 1500)
- Centro Di Riferimento Oncologico ( Site 1511)
- IRCCS Giovanni Paolo II. Ospedale Oncologico ( Site 1509)
- Azienda Ospedaliera Cannizzaro ( Site 1501)
- Istituto Nazionale dei Tumori ( Site 1510)
- Istituto Nazionale Tumori IRCCS Fondazione Pascale ( Site 1508)
- Fondazione Policlinico Universitario A. Gemelli ( Site 1512)
- Azienda Ospedaliera Santa Maria ( Site 1502)
- A.O. Verona-Ospedale Civile Maggiore Borgo-Trento ( Site 1504)
- Toho University Sakura Medical Center ( Site 0732)
- Ehime University Hospital ( Site 0745)
- Sapporo Medical University Hospital ( Site 0730)
- Kitasato University Hospital ( Site 0734)
- Yokohama City University Medical Center ( Site 0735)
- Nara Medical University Hospital ( Site 0744)
- Kindai University Hospital ( Site 0743)
- Osaka University Hospital ( Site 0742)
- Saitama Medical University International Medical Center ( Site 0737)
- Dokkyo Medical University Saitama Medical Center ( Site 0736)
- Hamamatsu University Hospital ( Site 0748)
- Yamaguchi University Hospital ( Site 0746)
- Chiba Cancer Center ( Site 0733)
- Harasanshin Hospital ( Site 0747)
- Nagano Municipal Hospital ( Site 0731)
- Osaka City University Hospital ( Site 0741)
- Toranomon Hospital ( Site 0740)
- Nippon Medical School Hospital ( Site 0738)
- Tokyo Women's Medical University Hospital ( Site 0739)
- Chonnam National University Hwasun Hospital ( Site 0406)
- National Cancer Center ( Site 0400)
- Seoul National University Bundang Hospital ( Site 0401)
- Kyungpook National University Chilgok Hospital ( Site 0404)
- Seoul National University Hospital ( Site 0405)
- Severance Hospital Yonsei University Health System ( Site 0402)
- Asan Medical Center ( Site 0403)
- Hospital San Lucas Cardiologica del Sureste ( Site 2606)
- Hospital Civil de Guadalajara Fray Antonio Alcalde ( Site 2607)
- Centro Estatal de Cancerologia de Chihuahua ( Site 2608)
- Grupo Medico Camino SC ( Site 2613)
- Centro Oncologico Internacional. SEDNA ( Site 2609)
- Boca Raton Clinical Research QTO ( Site 2611)
- Radboud University Medical Center ( Site 1606)
- Antoni van Leeuwenhoek Ziekenhuis ( Site 1603)
- Vrije Universiteit Medisch Centrum ( Site 1601)
- Isala Klinieken, Locatie Sophia ( Site 1604)
- Meander Medisch Centrum ( Site 1602)
- Franciscus Gasthuis en Vlietland ( Site 1605)
- St. Antonius Ziekenhuis ( Site 1600)
- Auckland City Hospital ( Site 0321)
- Hospital Nacional Carlos Alberto Seguin Escobedo ESSALUD ( Site 2700)
- Clinica Peruano Americana S.A. ( Site 2702)
- Hospital Nacional Guillermo Almenara Irigoyen ( Site 2708)
- Instituto de Oncologia y Radioterapia Clinica Ricardo Palma ( Site 2706)
- Hospital Militar Central [Lima, Peru] ( Site 2704)
- Szpital Uniwersytecki nr 1 im. Dr. Antoniego Jurasza w Bydgoszczy ( Site 1720)
- Centrum Onkologii im. Prof. Franciszka Lukaszczyka ( Site 1716)
- Nasz Lekarz Przychodnie Medyczne ( Site 1718)
- Szpital Uniwersytecki w Krakowie ( Site 1707)
- Radomskie Centrum Onkologii ( Site 1701)
- Wojewodzki Szpital im. Sw. Ojca Pio w Przemyslu ( Site 1700)
- Wojewodzki Szpital Specjalistyczny nr 4 w Bytomiu ( Site 1717)
- Szpital Kliniczny im. Przemienienia Panskiego Uniwersytetu Medycznego im. K. Marcinkowskiego w Pozna
- Szpital Wojewodzki im. Mikolaja Kopernika ( Site 1709)
- Twoja Przychodnia - Szczeciskie Centrum Medyczne ( Site 1721)
- Krasnoyarsk Regional Clinical Oncological Dispensary ( Site 1810)
- SBIH City clinical hospital named after D.D. Pletniov ( Site 1813)
- Russian Scientific Center of Roentgenoradiology ( Site 1800)
- Volga District Medical Center Federal Medical and Biological Agency ( Site 1805)
- Omsk Clinical Oncology Dispensary ( Site 1809)
- Instituto Catalan de Oncologia - ICO ( Site 1901)
- Hospital Josep Trueta ( Site 1900)
- Hospital Universitario Lucus Augusti ( Site 1905)
- Hospital Universitario Ramon y Cajal ( Site 1902)
- Hospital Clinico San Carlos ( Site 1906)
- Hospital 12 de Octubre de Madrid ( Site 1903)
- Hospital Virgen de la Macarena ( Site 1904)
- Kantonsspital Graubuenden ( Site 2003)
- Kantonsspital St. Gallen ( Site 2000)
- CHUV (centre hospitalier universitaire vaudois) ( Site 2002)
- Universitaetsspital Zuerich ( Site 2001)
- Kaohsiung Chang Gung Memorial Hospital ( Site 0504)
- National Cheng Kung University Hospital ( Site 0503)
- National Taiwan University Hospital ( Site 0500)
- Taipei Veterans General Hospital ( Site 0501)
- Chang Gung Medical Foundation. Linkou ( Site 0502)
- Chulalongkorn Hospital, Medical Oncology Unit ( Site 0600)
- Ramathibodi Hospital. ( Site 0601)
- Faculty of Medicine Siriraj Hospital ( Site 0602)
- Srinagarind Hospital ( Site 0604)
- Acibadem Adana Hastanesi ( Site 2106)
- Ankara Universitesi Tip Fakultesi. ( Site 2101)
- Hacettepe Universitesi Tıp Fakultesi ( Site 2105)
- Ankara Sehir Hastanesi ( Site 2103)
- Istanbul Uni. Cerrahpasa Tip Fakultesi ( Site 2100)
- Ege University Medical Faculty Tulay Aktas Oncology Hospital ( Site 2102)
- Konya Necmettin Erbakan University Medical Faculty ( Site 2104)
- Aberdeen Royal Infirmary ( Site 1315)
- Royal Cornwall Hospitals NHS Trust ( Site 1317)
- University College London Hospitals NHS Foundation Trust ( Site 1320)
- Royal Marsden NHS Foundation Trust ( Site 1318)
- Velindre Cancer Centre Hospital ( Site 1322)
Arms of the Study
Arm 1
Arm 2
Experimental
Placebo Comparator
Pembrolizumab + Enzalutamide + ADT
Placebo + Enzalutamide + ADT
Starting on Day 1 of each 21-day cycle, participants receive 200 mg pembrolizumab IV every 3 weeks (Q3W) for up to 35 cycles (approximately 2 years), plus 160 mg enzalutamide taken orally once daily, while maintaining continuous ADT with a luteinizing-hormone releasing hormone (LHRH) agonist or antagonist during study treatment. Participants will continue to receive enzalutamide and ADT until criteria for discontinuation are met.
Starting on Day 1 of each 21-day cycle, participants receive placebo IV Q3W for up to 35 cycles (approximately 2 years), plus 160 mg enzalutamide taken orally once daily, while maintaining continuous ADT with a LHRH agonist or antagonist during study treatment. Participants will continue to receive enzalutamide and ADT until criteria for discontinuation are met.