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)
Public ClinicalTrials.gov record NCT04191096. 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 Plus ADT Versus Placebo Plus Enzalutamide Plus ADT in Participants With Metastatic Hormone-Sensitive Prostate Cancer (mHSPC) (KEYNOTE-991)
Study identification
- NCT ID
- NCT04191096
- Recruitment status
- Completed
- Study type
- Interventional
- Phase
- Phase 3
- Lead sponsor
- Merck Sharp & Dohme LLC
- Industry
- Enrollment
- 1,251 participants
Conditions and interventions
Conditions
Interventions
- Androgen Deprivation Therapy (ADT) Drug
- Enzalutamide Drug
- Pembrolizumab Biological
- Placebo Other
Drug · Biological · Other
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
- Feb 11, 2020
- Primary completion
- Oct 30, 2022
- Completion
- Apr 7, 2026
- Last update posted
- Apr 28, 2026
2020 – 2026
United States locations
- U.S. sites
- 27
- U.S. states
- 19
- U.S. cities
- 25
| Facility | City | State | ZIP | Site status |
|---|---|---|---|---|
| Alaska Clinical Research Center ( Site 0274) | Anchorage | Alaska | 99503 | — |
| Providence Alaska Medical Center ( Site 0276) | Anchorage | Alaska | 99508 | — |
| City of Hope Medical Center ( Site 0217) | Duarte | California | 91010 | — |
| UCLA Hematology/Oncology - Santa Monica ( Site 0241) | Los Angeles | California | 90404 | — |
| University of Colorado, Anschutz Cancer Pavilion ( Site 0236) | Aurora | Colorado | 80045 | — |
| Hartford HealthCare Medical Group ( Site 0212) | Manchester | Connecticut | 06042 | — |
| Smilow Cancer Center at Yale-New Haven ( Site 0250) | New Haven | Connecticut | 06510 | — |
| Sibley Memorial Hospital ( Site 0275) | Washington D.C. | District of Columbia | 20016 | — |
| Winship Cancer Institute of Emory University ( Site 0209) | Atlanta | Georgia | 30322-1013 | — |
| The University of Chicago ( Site 0264) | Chicago | Illinois | 60637 | — |
| Springfield Clinic [Springfield, IL] ( Site 0240) | Springfield | Illinois | 62702 | — |
| Cotton-O'Neil Cancer Center ( Site 0228) | Topeka | Kansas | 66606 | — |
| The Sidney Kimmel Comprehensive Cancer Center ( Site 0204) | Baltimore | Maryland | 21287 | — |
| St. Vincent Frontier Cancer Center-Research ( Site 0213) | Billings | Montana | 59102 | — |
| Comprehensive Cancer Centers of Nevada ( Site 0269) | Las Vegas | Nevada | 89169 | — |
| Laura and Isaac Perlmutter Cancer Center at NYU Langone Health ( Site 0270) | New York | New York | 10016 | — |
| Weill Cornell Medical College ( Site 0263) | New York | New York | 10065 | — |
| Associated Medical Professionals of NY ( Site 0251) | Syracuse | New York | 13210 | — |
| Duke University ( Site 0206) | Durham | North Carolina | 27710 | — |
| TriState Urologic Services PSC Inc. dba The Urology Group ( Site 0253) | Cincinnati | Ohio | 45212 | — |
| MidLantic Urology ( Site 0273) | Bala-Cynwyd | Pennsylvania | 19004 | — |
| Ralph H. Johnson VA Center ( Site 0256) | Charleston | South Carolina | 29401 | — |
| Carolina Urologic Research Center ( Site 0259) | Myrtle Beach | South Carolina | 29572 | — |
| Urology Associates [Nashville, TN] ( Site 0233) | Nashville | Tennessee | 37209 | — |
| Inova Health System ( Site 0205) | Fairfax | Virginia | 22031 | — |
| Urology of Virginia ( Site 0224) | Virginia Beach | Virginia | 23462 | — |
| Fred Hutchinson Cancer Center ( Site 0258) | Seattle | Washington | 98109 | — |
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 207 non-U.S. sites.
About this trial record page
- What this page shows
- Public field values for ClinicalTrials.gov record NCT04191096, 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 Apr 28, 2026 · Synced May 16, 2026
Related: full search, browse by condition, browse by drug or therapy, browse by sponsor, browse by U.S. city.
Open the official record
The complete protocol, eligibility criteria, and contact information for NCT04191096 live on ClinicalTrials.gov.