Trial Purpose

The purpose of this study is to evaluate the efficacy of pembrolizumab (MK-3745) in the neoadjuvant (prior to surgery) or adjuvant (after surgery) treatment of previously untreated adults with gastric and gastroesophageal junction (GEJ) adenocarcinoma.

The primary study hypotheses are that:

Neoadjuvant and adjuvant pembrolizumab plus chemotherapy, followed by adjuvant pembrolizumab is superior to neoadjuvant and adjuvant placebo plus chemotherapy, followed by adjuvant placebo in terms of Event-free Survival (EFS) based on Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1), and
Neoadjuvant pembrolizumab plus chemotherapy is superior to neoadjuvant placebo plus chemotherapy in terms of rate of Pathological Complete Response (pathCR) at the time of surgery.

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When speaking to your doctor, please have the trial identifier number available.

About The Study

All patients who enroll in the trial will receive medication while on the study.

50% will receive pembrolizumab along with XP (cisplatin and capecitabine) or FP (cisplatin and 5-FU)* followed by surgical resection u2020

50% will receive placebo along with XP (cisplatin and capecitabine) or FP (cisplatin and 5-FU)* followed by surgical resection u2020


You will be assigned by chance (a process called randomization) to receive one of the above treatments.

*Your doctor will decide which chemotherapy treatment is best for you. A small group of patients will be given FLOT (5-FU, leucovorin, oxaliplatin, and docetaxel).

After surgery, you will receive XP or FP plus pembrolizumab or placebo followed by pembrolizumab or placebo alone.

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Phase 3

Tests the medicine or vaccine in large groups of trial participants (from several hundred to several thousand). For medicines, volunteers have the disease or condition the medicine is designed to treat. In vaccine studies, the volunteers may be healthy or have diseases or conditions. Phase 3 trials take place in hospitals, clinics, or physician offices.

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  • Actual study start date 9 October 2017
  • Estimated primary completion date 28 June 2024
  • Estimated study completion date 28 June 2024


Only a qualified healthcare professional can determine your eligibility. However, this information may be useful in starting a conversation with your doctor.

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Gastric Cancer, Gastroesophageal Junction Cancer

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Age Range

18 - No Age Maximum

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Trial locations

Locations provided may not reflect the most current site information. Please call the number provided in the location results to confirm.