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)
Public ClinicalTrials.gov record NCT03834493. Field values are reproduced from the official study page; the official ClinicalTrials.gov record remains the source of truth for eligibility, enrollment, and contact information.
Data is sourced from official ClinicalTrials.gov public API records. Always review the official ClinicalTrials.gov record for the latest information.
Official title
A Phase 3, Randomized, Double-blind Trial of Pembrolizumab (MK-3475) Plus Enzalutamide Versus Placebo Plus Enzalutamide in Participants With Metastatic Castration-Resistant Prostate Cancer (mCRPC) (KEYNOTE-641)
Brief summary
Reproduced verbatim from the official ClinicalTrials.gov record. Not medical advice.
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.
Study identification
- NCT ID
- NCT03834493
- Recruitment status
- Terminated
- Study type
- Interventional
- Phase
- Phase 3
- Enrollment
- 1,244 participants
Conditions and interventions
Conditions
Eligibility (public fields only)
- Age range
- 18 Years and older
- Sex
- Male
- Healthy volunteers
- Healthy volunteers not accepted
This page does not interpret eligibility. Detailed inclusion and exclusion criteria are on the official ClinicalTrials.gov record.
Study timeline
- Start date
- Jul 28, 2019 (Actual)
- Primary completion
- Dec 12, 2022 (Actual)
- Completion
- Jun 8, 2026 (Actual)
- Last update posted
- Sep 28, 2026
2019 – 2026
United States locations
- U.S. sites
- 28
- U.S. states
- 22
- U.S. cities
- 28
| Facility | City | State | ZIP | Site status |
|---|---|---|---|---|
| University of South Alabama, Mitchell Cancer Institute ( Site 0065) | Mobile | Alabama | 36604 | — |
| Providence Medical Foundation-Oncology ( Site 0069) | Fullerton | California | 92835 | — |
| UCLA Hematology/Oncology - Santa Monica ( Site 0081) | Los Angeles | California | 90404 | — |
| University of Colorado Cancer Center ( Site 0022) | Aurora | Colorado | 80045 | — |
| Smilow Cancer Hospital at Yale New Haven ( Site 0038) | New Haven | Connecticut | 06513 | — |
| Moffitt Cancer Center ( Site 0080) | Tampa | Florida | 33612 | — |
| Georgia Cancer Center at Augusta University ( Site 0026) | Augusta | Georgia | 30912 | — |
| Mount Sinai Hospital ( Site 0042) | Chicago | Illinois | 60608 | — |
| Methodist Hospitals. ( Site 0008) | Merrillville | Indiana | 46410 | — |
| Tulane Cancer Center ( Site 0066) | New Orleans | Louisiana | 70112 | — |
| University of Massachusetts Worcester ( Site 0053) | Worcester | Massachusetts | 01655 | — |
| Cancer & Hematology Centers of Western Michigan ( Site 0013) | Grand Rapids | Michigan | 49503 | — |
| Munson Medical Center ( Site 0030) | Traverse City | Michigan | 49684 | — |
| St. Vincent Frontier Cancer Center ( Site 0016) | Billings | Montana | 59102 | — |
| Oncology Hematology West, PC dba Nebraska Cancer Specialists ( Site 0034) | Omaha | Nebraska | 68130 | — |
| Comprehensive Cancer Centers of Nevada ( Site 0092) | Las Vegas | Nevada | 89169 | — |
| John Theurer Cancer Center at Hackensack University Medical Center ( Site 0004) | Hackensack | New Jersey | 07601 | — |
| Associated Medical Professionals of NY ( Site 0060) | Syracuse | New York | 13210 | — |
| W. G. Bill Hefner VA Medical Center ( Site 0029) | Salisbury | North Carolina | 28144 | — |
| Gabrail Cancer Center-Research ( Site 0096) | Canton | Ohio | 44718 | — |
| Tri-State Urologic Services PSC, Inc. ( Site 0094) | Cincinnati | Ohio | 45212 | — |
| University Hospitals Cleveland Medical Center ( Site 0036) | Cleveland | Ohio | 44106 | — |
| Oregon Health Science University ( Site 0031) | Portland | Oregon | 97239 | — |
| Carolina Urologic Research Center ( Site 0070) | Myrtle Beach | South Carolina | 29572 | — |
| Inova Schar Cancer Institute ( Site 0006) | Fairfax | Virginia | 22031 | — |
| Virginia Cancer Institute ( Site 0052) | Richmond | Virginia | 23230 | — |
| Blue Ridge Cancer Care ( Site 0086) | Roanoke | Virginia | 24014 | — |
| Froedtert Hospital & the Medical College of Wisconsin ( Site 0045) | Milwaukee | Wisconsin | 53226 | — |
Site contact phone numbers, emails, and investigator names are intentionally not displayed here. Open the official ClinicalTrials.gov record for site contact information.
Non-U.S. locations
This page focuses on the U.S. directory. The official record also lists 231 non-U.S. sites.
About this trial record page
- What this page shows
- Public field values for ClinicalTrials.gov record NCT03834493, including study identification, conditions, interventions, eligibility (age, sex, healthy volunteer), timeline, and U.S. site list.
- What this page does not do
- No medical advice, eligibility judgments, treatment recommendations, study quality scoring, or AI-generated medical summaries. No site contact phone numbers, emails, or investigator names.
- Where the data comes from
- Sourced from the official ClinicalTrials.gov public API. The official record is the source of truth.
- Last refresh
- Last update posted Sep 28, 2026 · Synced Oct 22, 2026
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Open the official record
The complete public registry record, listed eligibility criteria, and available contact information for NCT03834493 live on ClinicalTrials.gov.