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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)

Status
Completed
Phases
Phase 3
Study type
Interventional
Source
EU CTIS
Registry ID
CTIS2023-507024-24-00
Acronym
MK-3475-991
Enrollment
122
Registered
2024-01-05
Start date
2020-05-05
Completion date
2026-01-22
Last updated
2026-01-26

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Metastatic hormone sensitive prostate cancer

Brief summary

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, Overall Survival (OS)

Detailed description

Time to Initiation of the First Subsequent Anti-cancer Therapy or Death (TFST), Time to Symptomatic Skeletal-Related Event (TTSSRE), Time to Prostate-specific Antigen (PSA) Progression, Time to Radiographic Soft Tissue Progression Per Soft Tissue Rules of 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, Time to Pain Progression (TTPP) as Assessed by Brief Pain Inventory-Short Form (BPI-SF) Item 3 ("Worst Pain in 24 Hours") and Opiate Use, Time from Randomization to Disease Progression as Determined by Investigator Assessment after Next-line of Therapy or Death from Any Cause, Whichever Occurs First (PFS2), Prostate-specific Antigen (PSA) Response Rate, Prostate-specific antigen (PSA) Undetectable Rate, Objective Response Rate (ORR) 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, Duration of Response (DOR) 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, Number of Participants Who Experience an Adverse Event (AE), Number of Participants Who Discontinue Study Treatment Due to an Adverse Event (AE)

Interventions

DRUGENZALUTAMIDE
DRUGPEMBROLIZUMAB

Sponsors

Merck Sharp & Dohme LLC
Lead SponsorINDUSTRY

Eligibility

Sex/Gender
Male
Age
18 Years to No maximum

Design outcomes

Primary

MeasureTime frame
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, Overall Survival (OS)

Secondary

MeasureTime frame
Time to Initiation of the First Subsequent Anti-cancer Therapy or Death (TFST), Time to Symptomatic Skeletal-Related Event (TTSSRE), Time to Prostate-specific Antigen (PSA) Progression, Time to Radiographic Soft Tissue Progression Per Soft Tissue Rules of 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, Time to Pain Progression (TTPP) as Assessed by Brief Pain Inventory-Short Form (BPI-SF) Item 3 ("Worst Pain in 24 Hours") and Opiate Use, Time from Randomization to Disease Progression as Determined by Investigator Assessment after Next-line of Therapy or Death from Any Cause, Whichever Occurs First (PFS2), Prostate-specific Antigen (PSA) Response Rate, Prostate-specific antigen (PSA) Undetectable Rate, Objective Response Rate (ORR) Per Prostate Cancer Working Group (PCWG)-modified Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) as Assessed by Blind

Countries

Denmark, Ireland, Poland

Outcome results

None listed

Source: EU CTIS · Data processed: Feb 4, 2026