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)

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)

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 Tumours Version 1.1 (RECIST 1.1) as assessed by blinded independent central review.

Trial Description

Primary Outcome:

• Overall Survival (OS)
• 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

• Time to Initiation of the First Subsequent Anti-cancer Therapy or Death (TFST)
• 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
• 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 Analgesic Use (Analgesic Quantification Algorithm [AQA] Score)
• Time to First Symptomatic Skeletal-related Event (SSRE)
• 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