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)

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)

Summary:

This study will assess the efficacy and safety of pembrolizumab plus enzalutamide plus ADT versus placebo plus enzalutamide plus ADT in participants with mHSPC. The primary hypothesis is that in participants with mHSPC, the combination of pembrolizumab plus enzalutamide plus ADT is superior to placebo plus enzalutamide plus ADT with respect to 1) radiographic progression-free survival (rPFS) per Prostate Cancer Working Group (PCWG)-modified Response Evaluation Criteria in Solid Tumours (RECIST) 1.1 as assessed by blinded independent central review (BICR) and 2) overall survival (OS).

Trial Description

Primary Outcome:

• Radiographic Progression-free Survival (rPFS) Per Prostate Cancer Working Group (PCWG)-modified Response Evaluation Criteria in Solid Tumours Version 1.1 (RECIST 1.1) as Assessed by Blinded Independent Central Review
• Overall Survival (OS)

• 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 Tumours 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 Tumours 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 Tumours 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)

View this trial on ClinicalTrials.gov