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Pembrolizumab (MK-3475) Plus Chemotherapy Versus Placebo Plus Chemotherapy in Participants Gastric or Gastroesophageal Junction (GEJ) Adenocarcinoma (MK-3475-859/KEYNOTE-859)

NCT03675737 · Status: COMPLETED · Phase: PHASE3 · Type: INTERVENTIONAL · Enrollment: 1579

Last updated 2026-02-27

Study results available
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Summary

The purpose of this study is to evaluate the efficacy of pembrolizumab (MK-3745) in combination with chemotherapy (Cisplatin combined with 5-Fluorouracil \[FP regimen\] or oxaliplatin combined with capecitabine \[CAPOX regimen\]) versus placebo in combination with chemotherapy (FP or CAPOX regimens) in the treatment of human epidermal growth factor receptor 2 (HER2) negative advanced gastric or GEJ adenocarcinoma in adult participants.

The primary hypotheses of this study are that pembrolizumab plus chemotherapy is superior to placebo plus chemotherapy in terms of overall survival (OS).

Once a participant has achieved the study objective or the study has ended, the participant will be discontinued from this study and enrolled in an extension study (Keynote 587; NCT03486873) to continue protocol-defined assessments and treatment.

Conditions

  • Stomach Neoplasms

Interventions

BIOLOGICAL

Pembrolizumab

Administered as an IV infusion on Day 1 Q3W

DRUG

Cisplatin

Administered as an IV infusion on Day 1 Q3W

DRUG

5-fluorouracil

Administered as a continuous IV infusion on Days 1-5 Q3W

DRUG

oxaliplatin

Administered as an IV infusion on Day 1 Q3W

DRUG

capecitabine

Administered orally BID on Days 1 to 14 Q3W

DRUG

Placebo for Pembrolizumab

Administered as an IV infusion on Day 1 Q3W

Sponsors & Collaborators

Principal Investigators

  • Medical Director · Merck Sharp & Dohme LLC

Study Design

Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Model
PARALLEL

Eligibility

Min Age
18 Years
Sex
ALL
Healthy Volunteers
No

Timeline & Regulatory

Start
2018-11-08
Primary Completion
2022-10-03
Completion
2025-03-03
FDA Drug
Yes

Countries

  • United States
  • Argentina
  • Australia
  • Brazil
  • Canada
  • Chile
  • China
  • Colombia
  • Costa Rica
  • Czechia
  • Denmark
  • France
  • Germany
  • Guatemala
  • Hong Kong
  • Hungary
  • Ireland
  • Israel
  • Italy
  • Japan
  • Mexico
  • New Zealand
  • Peru
  • Poland
  • Russia
  • South Africa
  • South Korea
  • Spain
  • Switzerland
  • Taiwan
  • Turkey (Türkiye)
  • Ukraine
  • United Kingdom

Study Locations

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Entities

Drugs
Companies

Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT03675737 on ClinicalTrials.gov