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)
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.
Gastroesophageal Junction Adenocarcinoma,
Adenocarcinoma of the Gastroesophageal Junction,
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.
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