# KEYNOTE-811

Source: https://onco.cc/trials/keynote-811/  
OnCo record `keynote-811` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

KEYNOTE-811 showed that adding the immunotherapy pembrolizumab to trastuzumab and chemotherapy shrank HER2-positive stomach cancers more often and kept them under control for longer, with the gain concentrated in tumours that also express PD-L1.

## Summary

KEYNOTE-811 randomised 738 patients with previously untreated HER2-positive advanced gastric or gastro-oesophageal junction adenocarcinoma to trastuzumab plus fluoropyrimidine and platinum chemotherapy with pembrolizumab or with placebo. The dual primary endpoints were progression-free and overall survival.

At the first interim analysis the pembrolizumab arm had a markedly higher objective response rate, which supported accelerated approval in the United States in May 2021. Later analyses showed longer progression-free survival, with the benefit concentrated in tumours with a PD-L1 combined positive score of 1 or more, and the indication was narrowed to that group in 2023. Overall survival results followed in the same direction in the PD-L1-positive population.

## Fields

- Kind: Trial
- Status: positive
- Last checked: 2026-09-17
- Tags: subtype-trials
- Registry id: NCT03615326
- Phase: 3
- Setting: Untreated HER2-positive advanced gastric or gastro-oesophageal junction adenocarcinoma: trastuzumab and fluoropyrimidine-platinum chemotherapy with pembrolizumab or placebo
- Sponsor: Merck & Co. (MSD)
- Enrolled: 738
- Result: Higher response rate and longer progression-free survival with pembrolizumab added to trastuzumab and chemotherapy, with benefit concentrated in PD-L1-positive tumours; accelerated approval in May 2021, later limited to PD-L1 combined positive score of 1 or more.

## Sources

- ClinicalTrials.gov NCT03615326: https://clinicaltrials.gov/study/NCT03615326

## Connected records

- cancers: [Gastric & gastro-oesophageal junction cancer](https://onco.cc/cancers/gastric/), [HER2-positive gastric cancer](https://onco.cc/cancers/gastric-her2-positive/)
- drugs: [Capecitabine](https://onco.cc/drugs/capecitabine/), [Cisplatin](https://onco.cc/drugs/cisplatin/), [Fluorouracil (5-FU)](https://onco.cc/drugs/fluorouracil/), [Oxaliplatin](https://onco.cc/drugs/oxaliplatin/), [Pembrolizumab](https://onco.cc/drugs/pembrolizumab/), [Trastuzumab](https://onco.cc/drugs/trastuzumab/)
- companies: [Merck & Co. (MSD)](https://onco.cc/companies/merck/)
- people: [Yelena Y. Janjigian](https://onco.cc/people/yelena-janjigian/)
- key papers: [KEYNOTE-811: pembrolizumab plus trastuzumab and chemotherapy for HER2-positive gastric or gastro-oesophageal junction adenocarcinoma](https://onco.cc/key-papers/paper-keynote-811-janjigian-lancet-2023/)

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