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NCT03834493 · ClinicalTrials.gov registry record · Phase 3

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)

A Phase 3 study of Prostatic Neoplasms, sponsored by Merck Sharp & Dohme.

Active
Registry status
Phase 3
Development phase
1,244
Enrollment target
20
Study locations

NCT03834493: Active Phase 3 study of Prostatic Neoplasms, sponsored by Merck Sharp & Dohme.

NCT03834493 is a Phase 3 study of Prostatic Neoplasms that is active but no longer recruiting, run by Merck Sharp & Dohme. The registered enrollment target is 1,244 participants, above the 495-participant average among 65 other Prostatic Neoplasms trials with a reported enrollment target (151% higher). The trial reports 20 study locations across 18 states. According to ClinicalTrials.gov, the official US trial registry.

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The verdict

NCT03834493, a Phase 3 study of Prostatic Neoplasms, is active but no longer recruiting, sponsored by Merck Sharp & Dohme.

ACTIVE NOT RECRUITING
Registry status
Phase 3
Development phase
1,244 participants
Enrollment target
20
Study locations

Study Summary

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.

Primary Outcome

OS was defined as the time from randomization to death due to any cause. The OS for all participants is presented.

Conditions Studied

Prostatic Neoplasms

Interventions

  • BIOLOGICAL Pembrolizumab
  • DRUG Placebo
  • DRUG Enzalutamide

Study Locations (20)

California

  • Providence Medical Foundation-Oncology ( Site 0069) - Fullerton
  • UCLA Hematology/Oncology - Santa Monica ( Site 0081) - Los Angeles

Michigan

  • Cancer & Hematology Centers of Western Michigan ( Site 0013) - Grand Rapids
  • Munson Medical Center ( Site 0030) - Traverse City

Alabama

  • University of South Alabama, Mitchell Cancer Institute ( Site 0065) - Mobile

Colorado

  • University of Colorado Cancer Center ( Site 0022) - Aurora

Connecticut

  • Smilow Cancer Hospital at Yale New Haven ( Site 0038) - New Haven

Florida

  • Moffitt Cancer Center ( Site 0080) - Tampa

Georgia

  • Georgia Cancer Center at Augusta University ( Site 0026) - Augusta

Illinois

  • Mount Sinai Hospital ( Site 0042) - Chicago

Trial Details

FieldValue
Enrollment Target 1,244 participants
Start Date 2019-07-28
Est. Completion 2026-05-29
Phase Phase 3
Merck Sharp & Dohme

558 total trials

What the registry record for NCT03834493 still lists

NCT03834493 is an interventional study that assigns participants to a tested intervention. Its 1,244 participants enrollment target places it among the larger protocols in the corpus, above the 495-participant average among 65 other Prostatic Neoplasms trials with a reported enrollment target (151% higher).

The record links to 1 condition, with Prostatic Neoplasms appearing as the primary indexed condition, and to 3 interventions - of which Pembrolizumab is the first listed.

NCT03834493 names 20 study sites across 18 states, led by California, Michigan, Alabama.

Frequently Asked Questions

What is clinical trial NCT03834493 about?

NCT03834493 is a clinical study titled "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)". 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...

What is the current status of trial NCT03834493?

This trial is currently active not recruiting. It is a Phase 3 study. The enrollment target is 1,244 participants. The study started on 2019-07-28. Estimated completion is 2026-05-29.

What conditions does trial NCT03834493 study?

This clinical trial studies the following conditions: Prostatic Neoplasms.

What interventions are being tested in trial NCT03834493?

The interventions under investigation include: Pembrolizumab (BIOLOGICAL), Placebo (DRUG), Enzalutamide (DRUG).

Who is sponsoring clinical trial NCT03834493?

This trial is sponsored by Merck Sharp & Dohme, which has 558 total clinical trials registered on ClinicalTrials.gov.

Where is trial NCT03834493 being conducted?

This trial has 20 study locations across Alabama, California, Colorado, Connecticut, Florida. Contact the study sites directly through ClinicalTrials.gov for enrollment availability.

Learn More About Clinical Trials

Similar trials for Prostatic Neoplasms

Matched on the same primary condition, ranked to surface studies in the same phase first, then by recruiting status, no relevance scoring or editorial curation.

Where NCT03834493's enrollment target sits among peer trials

1,244 7th of 65 higher than 59 of 65 other Prostatic Neoplasms trials

participants (enrollment target), bucketed by value

Each bar is a band; taller bars hold more other Prostatic Neoplasms trials. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.

Source ClinicalTrials.gov registry export · 2026-08-08

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Related registry views

Source: ClinicalTrials.gov NCT03834493, the US trial registry maintained by the National Library of Medicine. NCT03834493 (large enrollment · wide site footprint · active not recruiting) retrieved and formatted by PlainTrial, see methodology.