Pembrolizumab/Placebo Plus Trastuzumab Plus Chemotherapy in Human Epidermal Growth Factor Receptor 2 Positive (HER2+) Advanced Gastric or Gastroesophageal Junction (GEJ) Adenocarcinoma (MK-3475-811/KEYNOTE-811)

  • End date
    Mar 20, 2024
  • participants needed
  • sponsor
    Merck Sharp & Dohme Corp.
Updated on 2 August 2021
measurable disease
gastric cancer
human epidermal growth factor
cancer chemotherapy
solid tumour


The study will compare the efficacy and safety of pembrolizumab plus trastuzumab in combination with standard of care (SOC) chemotherapy versus trastuzumab in combination with SOC chemotherapy in participants with HER2-positive gastric cancer. The primary hypotheses of the study are that pembrolizumab plus trastuzumab in combination with chemotherapy is superior to trastuzumab plus chemotherapy in terms of 1) progression free survival (PFS) per Response Evaluation Criteria in Solid Tumors 1.1 (RECIST 1.1) as assessed by blinded independent central review (BICR), and 2) overall survival (OS).


Pembrolizumab (200 mg) or placebo will be administered intravenously [IV] on day 1 of each 3-week cycle. Trastuzumab (8 mg/kg loading dose, 6 mg/kg maintenance dose) will be administered IV on day 1 of each 3-week cycle. SOC chemotherapy for the global cohort will either be FP (80 mg/m^2 cisplatin administered IV on Day 1 of each 3-week cycle and 800 mg/m^2 5-fluorouracil [5-FU] administered IV on Days 1-5 of each 3-week cycle) or CAPOX (1000 mg/m^2 capecitabine administered orally twice daily [BID] on days 1-14 of each 3-week cycle and 130 mg/m^2 oxaliplatin administered IV on Day 1 of each 3-week cycle). A Japan cohort will receive SOX chemotherapy consisting of S-1 (tegafur, 5-chloro-2,4-dihydroxypyridine [CDHP], and potassium oxonate [Oxo]) administered orally BID according to Body Surface Area (BSA) on Days 1-14 of each 3-week cycle and oxaliplatin (130 mg/m^2) administered IV on Day 1 each 3-week cycle.

Condition Gastropathy, Gastric Cancer, Stomach Discomfort, Gastroesophageal Junction Adenocarcinoma, Adenocarcinoma of the Gastroesophageal Junction, Stomach Cancer, gastric neoplasm, gastric tumor
Treatment Capecitabine, cisplatin, Placebo, Trastuzumab, Pembrolizumab, S-1, Oxaliplatin, 5-FU
Clinical Study IdentifierNCT03615326
SponsorMerck Sharp & Dohme Corp.
Last Modified on2 August 2021


Yes No Not Sure

Inclusion Criteria

Histologically or cytologically confirmed diagnosis of previously untreated, locally advanced unresectable or metastatic HER2 positive gastric or GEJ adenocarcinoma
HER2-positive defined as either immunohistochemistry (IHC) 3+ or IHC 2+ in combination with in-situ hybridization positive (ISH+) or fluorescent in-situ hybridization (FISH), as assessed by central review on primary or metastatic tumor
Has measurable disease as defined by RECIST 1.1 as determined by the site investigator
Male participants must agree to use approved contraception
Female participants who are not pregnant or breastfeeding, and who are either not a woman of childbearing potential (WOCBP), or are a WOCBP who agrees to use approved contraception
Has a performance status of 0 or 1 on the Eastern Cooperative Oncology Group (ECOG) Performance Scale within 3 days prior to the first dose of trial treatment
Has a life expectancy of greater than 6 months
Has adequate organ function

Exclusion Criteria

Has had previous therapy for locally advanced unresectable or metastatic gastric/GEJ cancer
Has had major surgery, open biopsy or significant traumatic injury within 28 days prior to randomization, or anticipation of the need for major surgery during the course of study treatment
Has had radiotherapy within 14 days of randomization
Has a known additional malignancy that is progressing or has required active treatment within the past 5 years
Has known active central nervous system (CNS) metastases and/or carcinomatous meningitis
Has an active autoimmune disease that has required systemic treatment in past 2 years
Has a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy
Has a history of (non-infectious) pneumonitis that required steroids or current pneumonitis
Has a known history of active tuberculosis (TB; Mycobacterium tuberculosis)
Has an active infection requiring systemic therapy
Has poorly controlled diarrhea
Accumulation of pleural, ascitic, or pericardial fluid requiring drainage or diuretic drugs within 2 weeks prior to enrollment. If the participant is receiving diuretic drugs for other reasons, it is acceptable
Has a history or current evidence of any condition, therapy, or laboratory abnormality that might confound the results of the trial, interfere with the participant's participation for the full duration of the trial, or is not in the best interest of the participant to participate, in the opinion of the treating investigator
Has peripheral neuropathy > Grade 1
Has a known psychiatric or substance abuse disorder that would interfere with cooperation with the requirements of the trial
A WOCBP who has a positive urine pregnancy test within 24 hours prior to randomization or treatment allocation
Has active or clinically significant cardiac disease
Has a known history of Human Immunodeficiency Virus (HIV) (HIV 1/2 antibodies)
Has a known history of Hepatitis B (defined as Hepatitis B surface antigen [HBsAg] reactive) or known active Hepatitis C virus (defined as HCV RNA [qualitative] is detected) infection
Has severe hypersensitivity (Grade 3) to pembrolizumab, trastuzumab, study chemotherapy agents and/or to any excipients, murine proteins, or platinum-containing products
Has had an allogeneic tissue/solid organ transplant
Has received prior therapy with an anti-PD-1, anti-PD-L1, or anti PD L2 agent or with an agent directed to another stimulatory or co-inhibitory T-cell receptor (e.g., cytotoxic T-lymphocyte-associated protein 4 [CTLA-4], OX 40, Cluster of Differentiation 137 [CD137])
Clear my responses

How to participate?

Step 1 Connect with a site
What happens next?
  • You can expect the study team to contact you via email or phone in the next few days.
  • Sign up as volunteer to help accelerate the development of new treatments and to get notified about similar trials.

You are contacting

Investigator Avatar

Primary Contact


Preferred Language
Other Language
Please verify that you are not a bot.

Additional screening procedures may be conducted by the study team before you can be confirmed eligible to participate.

Learn more

If you are confirmed eligible after full screening, you will be required to understand and sign the informed consent if you decide to enroll in the study. Once enrolled you may be asked to make scheduled visits over a period of time.

Learn more

Complete your scheduled study participation activities and then you are done. You may receive summary of study results if provided by the sponsor.

Learn more

Similar trials to consider


Browse trials for

Not finding what you're looking for?

Every year hundreds of thousands of volunteers step forward to participate in research. Sign up as a volunteer and receive email notifications when clinical trials are posted in the medical category of interest to you.

Sign up as volunteer

user name

Added by • 



Reply by • Private

Lorem ipsum dolor sit amet consectetur, adipisicing elit. Ipsa vel nobis alias. Quae eveniet velit voluptate quo doloribus maxime et dicta in sequi, corporis quod. Ea, dolor eius? Dolore, vel!

  The passcode will expire in None.

No annotations made yet

Add a private note
  • abc Select a piece of text from the left.
  • Add notes visible only to you.
  • Send it to people through a passcode protected link.
Add a private note