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)
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ClinicalTrials.gov Identifier: NCT03615326 |
Recruitment Status :
Active, not recruiting
First Posted : August 3, 2018
Last Update Posted : July 22, 2022
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Condition or disease | Intervention/treatment | Phase |
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Gastric Neoplasms Gastroesophageal Junction Adenocarcinoma | Biological: Pembrolizumab Biological: Placebo Drug: Cisplatin Drug: 5-FU Drug: Oxaliplatin Drug: Capecitabine Drug: S-1 Biological: Trastuzumab | Phase 3 |
Study Type : | Interventional (Clinical Trial) |
Estimated Enrollment : | 732 participants |
Allocation: | Randomized |
Intervention Model: | Parallel Assignment |
Masking: | Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor) |
Primary Purpose: | Treatment |
Official Title: | 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) |
Actual Study Start Date : | October 5, 2018 |
Estimated Primary Completion Date : | December 15, 2023 |
Estimated Study Completion Date : | December 30, 2024 |

Arm | Intervention/treatment |
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Experimental: Pembrolizumab +Trastuzumab + Chemotherapy
Participants receive 200 mg pembrolizumab IV every 3 weeks (Q3W) plus trastuzumab (8 mg/kg loading dose, 6 mg/kg maintenance thereafter) IV Q3W in combination with FP or CAPOX chemotherapy (Global Cohort) or SOX chemotherapy (Japan cohort).
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Biological: Pembrolizumab
200 mg on Day 1 of each 3-week cycle as an IV infusion.
Other Names:
Drug: Cisplatin 80 mg/m^2 on Day 1 of each 3-week cycle as an IV infusion, administered as part of FP chemotherapy regimen. Drug: 5-FU 800 mg/m^2/day continuous on Days 1-5 of each 3-week cycle (120 hours or per local standard), administered as part of FP chemotherapy regimen. Drug: Oxaliplatin 130 mg/m^2 on Day 1 of each 3-week cycle over 2 hours as an IV infusion, administered as part of CAPOX chemotherapy regimen and as part of SOX chemotherapy regimen. Drug: Capecitabine 1000 mg/m^2 as oral capsules BID on Days 1-14 of each 3-week cycle, administered as part of CAPOX chemotherapy regimen. Drug: S-1 Combination product of tegafur, CDHP, and Oxo. Oral capsules BID on Days 1-14 of each 3-week cycle based on body surface area (BSA): <1.25 m^2 BSA =40 mg, 1.25 to <1.5 m^2 BSA=50 mg, ≥1.5 m^2 BSA=60 mg. Administered as part of SOX chemotherapy regimen. Biological: Trastuzumab 8 mg/kg loading dose and then 6 mg/kg maintenance dose administered IV on day 1 of each 3-week cycle.
Other Name: Herceptin® |
Active Comparator: Placebo +Trastuzumab + Chemotherapy
Participants receive matched placebo to pembrolizumab IV Q3W plus trastuzumab (8mg/kg loading dose, 6mg/kg maintenance thereafter) IV Q3W in combination with FP or CAPOX chemotherapy (Global Cohort) or SOX chemotherapy (Japan cohort).
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Biological: Placebo
Solution for IV infusion on Day 1 of each 3-week cycle. Drug: Cisplatin 80 mg/m^2 on Day 1 of each 3-week cycle as an IV infusion, administered as part of FP chemotherapy regimen. Drug: 5-FU 800 mg/m^2/day continuous on Days 1-5 of each 3-week cycle (120 hours or per local standard), administered as part of FP chemotherapy regimen. Drug: Oxaliplatin 130 mg/m^2 on Day 1 of each 3-week cycle over 2 hours as an IV infusion, administered as part of CAPOX chemotherapy regimen and as part of SOX chemotherapy regimen. Drug: Capecitabine 1000 mg/m^2 as oral capsules BID on Days 1-14 of each 3-week cycle, administered as part of CAPOX chemotherapy regimen. Drug: S-1 Combination product of tegafur, CDHP, and Oxo. Oral capsules BID on Days 1-14 of each 3-week cycle based on body surface area (BSA): <1.25 m^2 BSA =40 mg, 1.25 to <1.5 m^2 BSA=50 mg, ≥1.5 m^2 BSA=60 mg. Administered as part of SOX chemotherapy regimen. Biological: Trastuzumab 8 mg/kg loading dose and then 6 mg/kg maintenance dose administered IV on day 1 of each 3-week cycle.
Other Name: Herceptin® |
- Progression Free Survival (PFS) per RECIST 1.1 assessed by BICR [ Time Frame: Up to approximately 4 years ]PFS is defined as the time from randomization to the first documented disease progression per RECIST 1.1 as assessed by BICR or death due to any cause, whichever occurs first. Per RECIST 1.1, progressive disease (PD) is defined as at least a 20% increase in the sum of diameters of target lesions, taking as reference the smallest sum on study In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of at least 5 mm. The appearance of one or more new lesions is also considered progression. PFS will be determined for each treatment arm.
- Overall Survival (OS) [ Time Frame: Up to approximately 5 years ]OS is defined as the time from randomization to death due to any cause. OS will be determined for each treatment arm.
- Objective Response Rate (ORR) per RECIST 1.1 assessed by BICR [ Time Frame: Up to approximately 5 years ]ORR is defined as the percentage of participants who have a Complete Response ([CR], disappearance of all evidence of disease) or Partial Response ([PR], regression of measurable disease and no new sites) per RECIST 1.1 as assessed by BICR. ORR will be determined for each treatment arm.
- Duration of Response (DOR) per RECIST 1.1 assessed by BICR [ Time Frame: Up to approximately 5 years ]For participants who demonstrate CR or PR, DOR is defined as the time from first response (CR or PR) to subsequent disease progression or death from any cause, whichever occurs first. DOR will be determined for each treatment arm.
- Adverse Events (AE) [ Time Frame: Up to approximately 5 years ]An AE is any untoward medical occurrence in a participant that is temporally associated with the use of study treatment, whether or not considered related to the study treatment. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of a study treatment. The number of participants who experience an AE will be reported for each treatment arm.
- Treatment Discontinuations Due to AEs [ Time Frame: Up to approximately 5 years ]An AE is any untoward medical occurrence in a participant that is temporally associated with the use of study treatment, whether or not considered related to the study treatment. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of a study treatment. The number of participants who discontinue study treatment due to an AE will be reported for each treatment arm.

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Ages Eligible for Study: | 18 Years and older (Adult, Older Adult) |
Sexes Eligible for Study: | All |
Accepts Healthy Volunteers: | No |
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])

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT03615326

Study Director: | Medical Director | Merck Sharp & Dohme LLC |
Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
Responsible Party: | Merck Sharp & Dohme LLC |
ClinicalTrials.gov Identifier: | NCT03615326 |
Other Study ID Numbers: |
3475-811 MK-3475-811 ( Other Identifier: Merck Protocol Number ) 184142 ( Registry Identifier: JAPAC-CTI ) 2018-000224-34 ( EudraCT Number ) |
First Posted: | August 3, 2018 Key Record Dates |
Last Update Posted: | July 22, 2022 |
Last Verified: | July 2022 |
Individual Participant Data (IPD) Sharing Statement: | |
Plan to Share IPD: | Yes |
Plan Description: | http://engagezone.msd.com/doc/ProcedureAccessClinicalTrialData.pdf |
URL: | http://engagezone.msd.com/ds_documentation.php |
Studies a U.S. FDA-regulated Drug Product: | Yes |
Studies a U.S. FDA-regulated Device Product: | No |
programmed cell death receptor 1 (PD-1) programmed cell death ligand 1 (PD-L1) anti-PD-1 |
anti PD-1 GEJ Gastric Cancer |
Adenocarcinoma Esophageal Neoplasms Stomach Neoplasms Carcinoma Neoplasms, Glandular and Epithelial Neoplasms by Histologic Type Neoplasms Gastrointestinal Neoplasms Digestive System Neoplasms Neoplasms by Site Head and Neck Neoplasms Digestive System Diseases Esophageal Diseases |
Gastrointestinal Diseases Stomach Diseases Pembrolizumab Capecitabine Oxaliplatin Trastuzumab Antineoplastic Agents Antineoplastic Agents, Immunological Immune Checkpoint Inhibitors Molecular Mechanisms of Pharmacological Action Antimetabolites, Antineoplastic Antimetabolites |