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Study of Pembrolizumab (MK-3475) Plus Enzalutamide Versus Placebo Plus Enzalutamide in Participants With Metastatic Castration-resistant Prostate Cancer (mCRPC) (MK-3475-641/KEYNOTE-641)

StatusTerminated
PhasePhase 3
Started2019-07-28
View on ClinicalTrials.gov ↗

Amendment history

The 49 most recent of 131 record versions are listed below. See every version on ClinicalTrials.gov ↗

2026-09-29
Reclassified as terminated (was completed)
Trial terminated: The study stopped due to futility
2026-06-19
Active, Not Recruiting→Completed Study Status v130
Trial statusActive, Not Recruiting→Completed
Completion dateestimated 2026-05-29→confirmed 2026-06-08
2025-07-08
Study Status, References v129
Publications1 to 2 entries
Graff JN, Burotto M, Fong PC, Pook DW, Zurawski B, Manneh Kopp R, Salinas J, Bylow KA, Kramer G, Ratta R, Kwiatkowski M, Retz M, Kwak C, Arranz Arija JA, Gurney H, Matsubara N, Villanueva L, Todenhofer T, Liang LW, Todoric J, Imai K, Stenzl A; KEYNOTE-641 Investigators. Pembrolizumab plus enzalutami [...]
2025-06-25
Study Identification, Study Status, Contacts/Locations, IPDSharing v128
Study sites258→259
2024-11-26
Study Status v127
Completion date2024-05-31→2026-05-29
Show 45 earlier versions
2023-11-27
Study Status, Outcome Measures, Document Section, Participant Flow, Baseline Characteristics, Outcome Measures (Results), Adverse Events, More Information v126
Results first postednot stated→2023-12-20
Secondary endpoints11 entries, revised
Objective Response Rate (ORROR) Per Prostate Cancer Working Group (PCWG)-modifiedModified Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) by as Assessed by Blinded Independent Central Review Duration of Response (DOR) Per Prostate Cancer Working Group (PCWG)-modifiedModified Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) by as Assessed by Blinded Independent Central Review Time to Ra [...] r Soft Tissue Rules of Prostate Cancer Working Group (PCWG)-modifiedModified Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) by as Assessed by Blin [...]
Primary endpoints2 entries, revised
Radiographic Progression-free Survival (rPFS) Per Prostate Cancer Working Group (PCWG)-modifiedModified Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) as Assessed by Blinded Independent Central Review
2023-06-13
Study Status v125
Completion date2023-12-28→2024-05-31
2023-06-09
Study Status, References v124
Re-verified, no change to tracked fields
2023-05-29
Study Status, Study Design, Outcome Measures v123
Secondary endpointsdetails revised at 11 of 11 entries
2023-05-21
Study Status v122
Completion date2025-02-28→2023-12-28
2023-04-26
Study Status, Study Design v121
Primary completion dateestimated 2023-11-12→confirmed 2022-12-12
Enrollment targetestimated 1240→confirmed 1244
2022-11-22
Study Identification, Study Status, Eligibility v120
Eligibility criteria+42 characters
[...] to the following during the study treatment period and for ≥45at least 90 days after the last dose of enzalutamide: Refrain from donating sperm, plus EITHER be abstinent OR must agree to use male condom Has pr [...] ), anti-programmed cell death-ligand 1 (anti-PD-L1), or anti-PD-L2 agent or with an agent directed to another stimulatory [...]
2022-06-15
Study Status, Study Design, Outcome Measures, Eligibility v119
Enrollment target1200→1240
Eligibility criteria+26 characters
[...] ystemic therapy Has a history of (noninfectious) pneumonitis/interstitial lung disease that required steroids or current pneumonitis/interstitial [...]
Secondary endpointsdetails revised at 11 of 11 entries
2022-05-10
Recruiting→Active, Not Recruiting Study Status, Contacts/Locations v118
Trial statusRecruiting→Active, Not Recruiting
Study sitesdetails revised at 258 of 258 sites
2022-04-29
Study Status, Contacts/Locations v117
Study sitesdetails revised at 2 of 258 sites
2022-04-20
Study Status, Contacts/Locations v116
Study sitesdetails revised at 2 of 258 sites
2022-04-13
Study Status, Contacts/Locations v115
Study sitesdetails revised at 3 of 258 sites
2022-04-07
Study Status, Contacts/Locations v114
Study sites258 entries, revised
Medizinische UniversitaetUniversität Wien ( Site 0375)
2022-03-30
Study Status, Contacts/Locations v113
Study sitesdetails revised at 5 of 258 sites
2022-03-24
Study Status, Contacts/Locations v112
Study sites257→258
2022-03-17
Study Status, Contacts/Locations v111
Study sites257 entries, revised
Rambam MedicalHealth CenterCare Campus-Oncology Division ( Site 0543)
2022-03-11
Study Status, Contacts/Locations v110
Study sitesdetails revised at 6 of 257 sites
2022-03-04
Study Status, Contacts/Locations v109
Study sitesdetails revised at 3 of 257 sites
2022-02-25
Study Status, Contacts/Locations v108
Study sitesdetails revised at 1 of 257 sites
2022-02-16
Study Status, Contacts/Locations v107
Study sites256→257
2022-02-10
Study Status, Contacts/Locations v106
Study sites255→256
2022-02-04
Study Status, Contacts/Locations v105
Study sites254→255
2022-01-21
Study Status, Contacts/Locations v104
Study sites254 entries, revised
Assaf HarofeHarofeh Medical Center Nephrology division ( Site 0547)
2022-01-12
Study Identification, Study Status, Contacts/Locations v103
Study sites252→254
2021-12-29
Study Status, Contacts/Locations v102
Study sitesdetails revised at 1 of 252 sites
2021-12-23
Study Status, Contacts/Locations v101
Study sites251→252
2021-12-17
Study Status, Contacts/Locations v100
Study sitesdetails revised at 5 of 251 sites
2021-12-03
Study Status, Contacts/Locations v99
Study sites251 entries, revised
IBCC - Instituto Brasileiro de Controle do Câncer-CentroNúcleo de Pesquisa Clínica da Rede São Camilo ( Site 1040)
2021-11-25
Study Status, Contacts/Locations v98
Study sites248→251
2021-11-18
Study Status, Contacts/Locations v97
Study sites246→248
2021-11-09
Study Status, Outcome Measures, Eligibility, Contacts/Locations v96
Study sites240→246
Eligibility criteria-86 characters
The main inclusion and exclusion criteria include but are not limited to the following: Inclusion Criteria: Has histologically- or cytologically-con [...] to the following during the study treatment period and for ≥9045 days after the last dose of enzalutamide: Refrain from donating sperm PLUS Use contraception unless confirmed toEITHER be azoospermicabstinent (vasectomized or secondary to medical cause) ParticipantsOR must agree to use male condom when engaging in any activity that allows for passage of ejaculate to another person of any sex Has provided newly obtained core or excisional biopsy (obt [...] [...]
Secondary endpointsdetails revised at 11 of 11 entries
2021-10-08
Study Status, Contacts/Locations v95
Completion date2024-12-30→2025-02-28
Study sitesdetails revised at 2 of 240 sites
2021-09-30
Study Status, Contacts/Locations v94
Study sites238→240
2021-09-23
Study Status, Contacts/Locations v93
Study sitesdetails revised at 6 of 238 sites
2021-09-15
Study Status, Contacts/Locations v92
Study sites232→238
2021-08-27
Study Status, Contacts/Locations v91
Study sites231→232
2021-08-20
Study Status, Contacts/Locations v90
Study sites228→231
2021-08-12
Study Status, Contacts/Locations v89
Study sites227→228
2021-08-05
Study Status, Contacts/Locations v88
Study sitesdetails revised at 2 of 227 sites
2021-07-29
Study Status, Contacts/Locations v87
Study sites227 entries, revised
Royal Marsden Hospital (Sutton) ( Site 0526)
2021-07-23
Study Status, Contacts/Locations v86
Study sites227 entries, revised
Bradford Hill Centro de Investigaciones ClinicasBradfordhill ( Site 1044)
2021-07-15
Study Status, Contacts/Locations v85
Study sitesdetails revised at 2 of 227 sites
2021-07-07
Study Status, Contacts/Locations v84
Study sites226→227
2021-07-02
Study Status, Contacts/Locations v83
Study sites224→226
2021-06-24
Study Status, Contacts/Locations v82
Study sites224 entries, revised
UCLA Department of MedicineHematology/Oncology - HematologySanta & OncologyMonica ( Site 0081)
Merck (MSD)
401 trials monitored
See 24 trials at risk
Prostate Cancer
2,471 trials monitored
See 156 trials at risk
The purpose of this study is to assess the efficacy and safety of the combination of pembrolizumab (MK-3475) and enzalutamide in the treatment of men with metastatic castration-resistant prostate cancer (mCRPC) who have not received chemotherapy for mCRPC, are abiraterone-naïve, or are intolerant to or progressed on abiraterone acetate. There are two primary study hypotheses. Hypothesis 1: The combination of pembrolizumab plus enzalutamide is superior to placebo plus enzalutamide with respect to Overall Survival (OS). Hypothesis 2: The combination of pembrolizumab plus enzalutamide is superior to placebo plus enzalutamide with respect to Radiographic Progression-free Survival (rPFS) per Prostate Cancer Working Group (PCWG)-modified Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) as assessed by blinded independent central review.
Trial Details
NCT Number NCT03834493
Lead Sponsor Merck Sharp & Dohme LLC
Conditions Prostatic Neoplasms
Enrollment 1,244 participants
Start Date 2019-07-28
Primary Completion 2022-12-12 (estimated)
Study Completion 2026-06-08 (estimated)
Updated on ClinicalTrials.gov 2026-09-28