A Phase III, Randomized, Double-blind Trial Comparing Trastuzumab Plus Chemotherapy and Pembrolizumab With Trastuzumab Plus Chemotherapy and Placebo as First-line Treatment in Participants With HER2 Positive Advanced Gastric or Gastroesophageal Junction Adenocarcinoma (KEYNOTE 811)

Status

Completed

Phases

Phase 3

Study type

Interventional

Source

EU CTIS

Registry ID

CTIS2023-508253-98-00

Acronym

MK-3475-811

Enrollment

167

Registered

2023-12-14

Start date

2018-10-05

Completion date

2025-11-11

Last updated

2025-09-12

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

Conditions

Gastric or gastroesophageal junction (GEJ) adenocarcinoma

Brief summary

Progression-Free Survival (PFS) per RECIST 1.1 assessed by Blinded Independent Central Review (BICR), Overall Survival (OS)

Detailed description

Objective Response Rate (ORR) per RECIST 1.1 assessed by BICR, Duration of Response (DOR) per RECIST 1.1 assessed by BICR, Number of Participants Who Experience an Adverse Event (AE), Number of Participants Who Discontinue Study Treatment Due to an AE

Interventions

DRUGFLUOROURACIL

DRUGCISPLATIN

DRUGCAPECITABINE

DRUGTRASTUZUMAB

DRUGPlacebo for Pembrolizumab

DRUGOXALIPLATIN

DRUGKEYTRUDA 25 mg/mL concentrate for solution for infusion

Eligibility

Sex/Gender

All

Age

18 Years to No maximum

Design outcomes

Primary

Measure	Time frame
Progression-Free Survival (PFS) per RECIST 1.1 assessed by Blinded Independent Central Review (BICR), Overall Survival (OS)	—

Secondary

Measure	Time frame
Objective Response Rate (ORR) per RECIST 1.1 assessed by BICR, Duration of Response (DOR) per RECIST 1.1 assessed by BICR, Number of Participants Who Experience an Adverse Event (AE), Number of Participants Who Discontinue Study Treatment Due to an AE	—

Countries

France, Germany, Ireland, Italy, Poland, Spain

Outcome results

None listed

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