Study of Pembrolizumab (MK-3475) Plus Chemotherapy Versus Placebo Plus Chemotherapy in Participants With Gastric or Gastroesophageal Junction (GEJ) Adenocarcinoma (MK-3475-585/KEYNOTE-585)

February 13, 2026 updated by: Merck Sharp & Dohme LLC

A Phase III, Randomized, Double-Blind, Clinical Trial of Pembrolizumab (MK-3475) Plus Chemotherapy (XP or FP) Versus Placebo Plus Chemotherapy (XP or FP) as Neoadjuvant/Adjuvant Treatment for Subjects With Gastric and Gastroesophageal Junction (GEJ) Adenocarcinoma (KEYNOTE-585)

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.

With Amendment 10, upon study completion, participants will be discontinued and may be enrolled in an extension study.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Actual)

1007

Phase

  • Phase 3

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Belgium
    • Bruxelles-Capitale, Region de
      • Brussels, Bruxelles-Capitale, Region de, Belgium, 1000
        • Institut Jules Bordet ( Site 0480)
      • Brussels, Bruxelles-Capitale, Region de, Belgium, 1070
        • Hopital Erasme ULB ( Site 0484)
      • Brussels, Bruxelles-Capitale, Region de, Belgium, 1200
        • UCL Saint Luc ( Site 0479)
    • Hainaut
      • Charleroi, Hainaut, Belgium, 6000
        • Grand Hopital de Charleroi ( Site 0478)
    • Liege
      • Liège, Liege, Belgium, 4000
        • CHU de Liege ( Site 0482)
    • Namur
      • Yvoir, Namur, Belgium, 5530
        • CHU UCL Namur Site de Godinne ( Site 0485)
    • Oost-Vlaanderen
      • Ghent, Oost-Vlaanderen, Belgium, 9000
        • UZ Gent ( Site 0486)
    • Vlaams-Brabant
      • Leuven, Vlaams-Brabant, Belgium, 3000
        • UZ Leuven ( Site 0483)
    • West-Vlaanderen
      • Kortrijk, West-Vlaanderen, Belgium, 8500
        • AZ Groeninge ( Site 0481)
  • Brazil
      • Rio de Janeiro, Brazil, 20230-130
        • Instituto Nacional Do Cancer Jose Alencar Gomes Da Silva ( Site 0307)
      • São Paulo, Brazil, 01246-000
        • Instituto do Cancer do Estado de Sao Paulo - ICESP ( Site 0305)
      • São Paulo, Brazil, 05652-900
        • Hospital Israelita Albert Einstein ( Site 0309)
    • Ceará
      • Fortaleza, Ceará, Brazil, 60430-230
        • Instituto do Cancer do Ceara ( Site 0311)
    • Rio Grande do Sul
      • Porto Alegre, Rio Grande do Sul, Brazil, 90610-000
        • Uniao Brasileira de Educacao e Assistencia Hospital Sao Lucas da Pucrs ( Site 0308)
    • Santa Catarina
      • Florianópolis, Santa Catarina, Brazil, 88034-000
        • CEPON - Centro de Pesquisas Oncologicas ( Site 0302)
    • São Paulo
      • Barretos, São Paulo, Brazil, 14784-400
        • Fundacao Pio XII - Hospital de Cancer de Barretos ( Site 0301)
      • Sao Jose Rio Preto, São Paulo, Brazil, 15090-000
        • Hospital de Base de Sao Jose de Rio Preto ( Site 0304)
  • Canada
    • Alberta
      • Edmonton, Alberta, Canada, T6G 1Z2
        • Cross Cancer Institute ( Site 0033)
    • New Brunswick
      • Moncton, New Brunswick, Canada, E1C 6Z8
        • Moncton Hospital - Horizon Health Network ( Site 0038)
    • Ontario
      • Toronto, Ontario, Canada, M4N 3M5
        • Sunnybrook Research Institute ( Site 0032)
    • Quebec
      • Greenfield Park, Quebec, Canada, J4V 2H1
        • CISSS de la Monteregie-Centre ( Site 0039)
      • Montreal, Quebec, Canada, H1T 2M4
        • CIUSSS de l Est de L Ile de Montreal - Hopital Maisonneuve-Rosemont ( Site 0040)
      • Montreal, Quebec, Canada, H3T 1E2
        • Jewish General Hospital ( Site 0034)
      • Québec, Quebec, Canada, G1R 2J6
        • CHU de Quebec - Hotel-Dieu de Quebec ( Site 0042)
      • Sherbrooke, Quebec, Canada, J1H 5N4
        • CIUSSS de l Estrie - CHUS - Centre Hosp. Univ. Sherbrooke ( Site 0035)
  • Chile
    • Lbtdr Gen Bernardo O Higgins
      • Rancagua, Lbtdr Gen Bernardo O Higgins, Chile, 2820000
        • Hospital Regional Rancagua Libertador Bernardo O Higgins ( Site 0299)
    • Region M. de Santiago
      • Santiago, Region M. de Santiago, Chile, 7500921
        • Fundacion Arturo Lopez Perez FALP ( Site 0286)
      • Santiago, Region M. de Santiago, Chile, 8330032
        • Pontificia Universidad Catolica de Chile ( Site 0285)
      • Santiago, Region M. de Santiago, Chile, 8380456
        • Hospital Clinico Universidad de Chile ( Site 0287)
    • Región de la Araucanía
      • Temuco, Región de la Araucanía, Chile, 4810469
        • Instituto Clinico del Sur. ICOS ( Site 0290)
  • China
    • Beijing Municipality
      • Beijing, Beijing Municipality, China, 100142
        • Beijing Cancer Hospital ( Site 0221)
    • Zhejiang
      • Hangzhou, Zhejiang, China, 310022
        • Zhejiang Cancer Hospital ( Site 0231)
      • Hangzhou, Zhejiang, China, 430030
        • Sir Run Run Shaw Hospital ( Site 0233)
  • Estonia
    • Harju
      • Tallinn, Harju, Estonia, 13419
        • SA Pohja-Eesti Regionaalhaigla ( Site 0526)
  • France
      • Paris, France, 75012
        • CHU Hopital Saint Antoine ( Site 0471)
      • Paris, France, 75014
        • Institut Mutualiste Montsouris ( Site 0463)
    • Auvergne
      • Lyon, Auvergne, France, 69008
        • Hopital Prive Jean Mermoz ( Site 0462)
    • Bouches-du-Rhone
      • Marseille, Bouches-du-Rhone, France, 13009
        • Institut Paoli Calmettes ( Site 0472)
    • Champagne-Ardenne
      • Reims, Champagne-Ardenne, France, 51092
        • CHU Reims - Hopital Robert Debre ( Site 0465)
    • Finistere
      • Brest, Finistere, France, 29200
        • CHU Brest - Institut de Cancerologie et d Hematologie ( Site 0474)
    • Haute-Garonne
      • Toulouse, Haute-Garonne, France, 31059
        • CHU Toulouse - Hopital Rangueil ( Site 0470)
    • Herault
      • Montpellier, Herault, France, 34298
        • Institut du Cancer de Montpellier ( Site 0473)
    • Ille-et-Vilaine
      • Rennes, Ille-et-Vilaine, France, 35042
        • Centre Eugene Marquis ( Site 0466)
    • Loire-Atlantique
      • Saint-Herblain, Loire-Atlantique, France, 44805
        • Institut de Cancerologie de l Ouest Centre Rene Gauducheau ( Site 0469)
    • Nord
      • Lille, Nord, France, 59037
        • CHRU Lille - Hopital Claude Huriez ( Site 0461)
    • Vienne
      • Poitiers, Vienne, France, 86021
        • CHU Poitiers - Pole Regional de Cancerologie ( Site 0467)
  • Germany
      • Hamburg, Germany, 20249
        • Haematologisch-Onkologische Praxis Eppendorf Facharztzentrum Eppendorf - Hope ( Site 0454)
    • Baden-Wurttemberg
      • Esslingen am Neckar, Baden-Wurttemberg, Germany, 73730
        • Klinikum Esslingen GmbH ( Site 0453)
      • Freiburg im Breisgau, Baden-Wurttemberg, Germany, 79106
        • Universitaetsklinikum Freiburg ( Site 0450)
    • Bavaria
      • Munich, Bavaria, Germany, 81377
        • Klinikum der Universitaet in Muenchen ( Site 0446)
    • Lower Saxony
      • Hanover, Lower Saxony, Germany, 30625
        • Medizinische Hochschule Hannover ( Site 0449)
    • North Rhine-Westphalia
      • Essen, North Rhine-Westphalia, Germany, 45136
        • Kliniken Essen Mitte Gmbh Evang. Huyssens Stiftung ( Site 0445)
    • Rhineland-Palatinate
      • Mainz, Rhineland-Palatinate, Germany, 55131
        • Medizinische klinilk und Poliklinik Johannes Gutenberg Univ ( Site 0455)
    • Saxony
      • Dresden, Saxony, Germany, 01307
        • Universitaetsklinikum Carl Gustav Carus der TU Dresden ( Site 0448)
  • Guatemala
      • Guatemala City, Guatemala, 01010
        • Integra Cancer Institute ( Site 0262)
      • Guatemala City, Guatemala, 01015
        • Grupo Medico Angeles ( Site 0261)
      • Quetzaltenango, Guatemala, 09002
        • Centro Medico Integral De Cancerología (CEMIC) ( Site 0260)
  • Israel
      • Haifa, Israel, 31096
        • Rambam Health Care Campus ( Site 0381)
      • Jerusalem, Israel, 9112001
        • Hadassah Medical Center. Ein Kerem ( Site 0383)
      • Petah Tikva, Israel, 4941492
        • Rabin-Medical Center ( Site 0384)
      • Ramat Gan, Israel, 5265601
        • Sheba Medical center ( Site 0387)
    • Central District
      • Kfar Saba, Central District, Israel, 4428164
        • Meir medical center ( Site 0386)
    • Southern District
      • Beersheba, Southern District, Israel, 8410101
        • Soroka University M.C ( Site 0385)
    • Tell Abib
      • Tel Aviv, Tell Abib, Israel, 6423906
        • Sourasky Medical Center. ( Site 0382)
  • Italy
      • Modena, Italy, 41125
        • Azienda Ospedaliero Universitaria di Modena Policlinico ( Site 0429)
      • Napoli, Italy, 80131
        • Seconda Universita Napoli ( Site 0436)
      • Udine, Italy, 33100
        • A.O.U. Santa Maria della Misericordia di Udine ( Site 0434)
    • Abruzzo
      • Padova, Abruzzo, Italy, 35128
        • IRCCS Istituto Oncologico Veneto ( Site 0431)
    • Lombardy
      • Milan, Lombardy, Italy, 20133
        • Fondazione IRCCS Istituto Nazionale dei Tumori di Milano ( Site 0430)
    • Milano
      • Rozzano, Milano, Italy, 20089
        • Istituto Clinico Humanitas Research Hospital ( Site 0432)
      • San Donato Milanese, Milano, Italy, 20097
        • IRCCS Policlinico San Donato ( Site 0433)
  • Japan
      • Chiba, Japan, 260-8717
        • Chiba Cancer Center ( Site 0180)
      • Fukuoka, Japan, 811-1395
        • National Hospital Organization Kyushu Cancer Center ( Site 0172)
      • Fukuoka, Japan, 812-8582
        • Kyushu University Hospital ( Site 0173)
      • Gifu, Japan, 501-1194
        • Gifu University Hospital ( Site 0166)
      • Hiroshima, Japan, 730-8518
        • Hiroshima City Hiroshima Citizens Hospital ( Site 0171)
      • Kochi, Japan, 781-8555
        • Kochi Health Sciences Center ( Site 0189)
      • Kumamoto, Japan, 860-8556
        • Kumamoto University Hospital ( Site 0164)
      • Niigata, Japan, 951-8566
        • Niigata Cancer Center Hospital ( Site 0169)
      • Osaka, Japan, 541-8567
        • Osaka International Cancer Institute ( Site 0161)
      • Osaka, Japan, 558-8558
        • Osaka General Medical Center ( Site 0159)
      • Tokyo, Japan, 104-0045
        • National Cancer Center Hospital ( Site 0179)
      • Tokyo, Japan, 113-8677
        • Tokyo Metropolitan Komagome Hospital ( Site 0183)
      • Tokyo, Japan, 135-8550
        • The Cancer Institute Hospital of JFCR ( Site 0185)
      • Toyama, Japan, 930-8550
        • Toyama Prefectural Central Hospital ( Site 0163)
    • Aichi-ken
      • Nagoya, Aichi-ken, Japan, 464-8681
        • Aichi Cancer Center Hospital ( Site 0165)
    • Chiba
      • Kashiwa, Chiba, Japan, 277-8577
        • National Cancer Center Hospital East ( Site 0178)
    • Ehime
      • Matsuyama, Ehime, Japan, 791-0280
        • National Hospital Organization Shikoku Cancer Center ( Site 0186)
    • Hokkaido
      • Sapporo, Hokkaido, Japan, 060-8648
        • Hokkaido University Hospital ( Site 0160)
    • Hyōgo
      • Akashi, Hyōgo, Japan, 673-8558
        • Hyogo Cancer Center ( Site 0182)
      • Kobe, Hyōgo, Japan, 650-0017
        • Kobe University Hospital ( Site 0188)
      • Kobe, Hyōgo, Japan, 650-0047
        • Kobe City Medical Center General Hospital ( Site 0181)
    • Ibaraki
      • Kasama, Ibaraki, Japan, 309-1793
        • Ibaraki Prefectural Central Hospital ( Site 0177)
    • Iwate
      • Shiwa-gun, Iwate, Japan, 028-3695
        • Iwate Medical University Hospital ( Site 0184)
    • Kanagawa
      • Kawasaki, Kanagawa, Japan, 216-8511
        • St. Marianna University School of Medicine Hospital ( Site 0187)
      • Yokohama, Kanagawa, Japan, 241-8515
        • Kanagawa Cancer Center ( Site 0167)
    • Osaka
      • Hirakata, Osaka, Japan, 573-1191
        • Kansai Medical University Hospital ( Site 0190)
      • Suita, Osaka, Japan, 565-0871
        • Osaka University Hospital ( Site 0162)
      • Takatsuki, Osaka, Japan, 569-8686
        • Osaka Medical College Hospital ( Site 0168)
    • Saitama
      • Kitaadachi-gun, Saitama, Japan, 362-0806
        • Saitama Cancer Center ( Site 0170)
    • Shizuoka
      • Sunto-gun, Shizuoka, Japan, 411-8777
        • Shizuoka Cancer Center Hospital and Research Institute ( Site 0176)
  • Latvia
      • Riga, Latvia, 1079
        • Riga East Clinical University Hospital ( Site 0550)
  • Lithuania
      • Kaunas, Lithuania, 50161
        • LSMUL Kauno Klinikos ( Site 0570)
      • Vilnius, Lithuania, 08406
        • Nacionalinis Vezio Institutas ( Site 0569)
      • Vilnius, Lithuania, 08460
        • Vilniaus Universiteto Ligonine Santaros Klinikos ( Site 0568)
  • Malaysia
      • Kuala Lumpur, Malaysia, 50586
        • Hospital Kuala Lumpur ( Site 0146)
      • Kuala Lumpur, Malaysia, 59100
        • University Malaya Medical Centre ( Site 0143)
  • Philippines
    • National Capital Region
      • Quezon City, National Capital Region, Philippines, 1102
        • St. Luke s Medical Center ( Site 0622)
  • Poland
    • Lesser Poland Voivodeship
      • Krakow, Lesser Poland Voivodeship, Poland, 31-501
        • Szpital Uniwersytecki w Krakowie ( Site 0352)
    • Lower Silesian Voivodeship
      • Wroclaw, Lower Silesian Voivodeship, Poland, 51-124
        • Wojewodzki Szpital Specjalistyczny we Wroclawiu ( Site 0358)
    • Lublin Voivodeship
      • Lublin, Lublin Voivodeship, Poland, 20-080
        • Samodzielny Publiczny Szpital Kliniczny Nr 1 w Lublinie ( Site 0351)
    • Masovian Voivodeship
      • Warsaw, Masovian Voivodeship, Poland, 02-034
        • Narodowy Instytut Onkologii im. Marii Sklodowskiej-Curie ( Site 0349)
      • Wieliszew, Masovian Voivodeship, Poland, 05-135
        • Mazowiecki Szpital Onkologiczny ( Site 0363)
    • Pomeranian Voivodeship
      • Kościerzyna, Pomeranian Voivodeship, Poland, 83-400
        • Szpital Specjalistyczny w Koscierzynie Sp. z o.o. ( Site 0353)
    • Silesian Voivodeship
      • Bielsko-Biala, Silesian Voivodeship, Poland, 43-300
        • Beskidzkie Centrum Onkologii im. Jana Pawla II ( Site 0354)
      • Gliwice, Silesian Voivodeship, Poland, 44-101
        • Narodowy Instytut Onkologii im. Marii Sklodowskiej-Curie ( Site 0361)
      • Rybnik, Silesian Voivodeship, Poland, 44-200
        • SPZOZ WSS nr 3 w Rybniku ( Site 0357)
  • Russia
    • Kaluzskaja Oblast
      • Kaluga, Kaluzskaja Oblast, Russia, 248007
        • Kaluga Regional Clinical Oncology Center ( Site 0345)
    • Leningradskaya Oblast'
      • Saint Petersburg, Leningradskaya Oblast', Russia, 194291
        • SBHI Leningrad Regional Clinical Hospital ( Site 0496)
    • Moscow
      • Moscow, Moscow, Russia, 105203
        • National Medical and Surgical Center n.a. N.I.Pirogov ( Site 0338)
      • Moscow, Moscow, Russia, 115478
        • Blokhin National Medical Oncology ( Site 0494)
    • Sankt-Peterburg
      • Saint Petersburg, Sankt-Peterburg, Russia, 188663
        • Leningrad Regional Oncology Center ( Site 0335)
      • Saint Petersburg, Sankt-Peterburg, Russia, 197758
        • Scientific Research Oncology Institute n.a. N.N.Petrov ( Site 0344)
      • Saint Petersburg, Sankt-Peterburg, Russia, 198255
        • City clinical oncological dispensary ( Site 0336)
    • Tomsk Oblast
      • Tomsk, Tomsk Oblast, Russia, 634028
        • Tomsk Scientific Research Institute of Oncology ( Site 0337)
  • Singapore
    • Central Singapore
      • Singapore, Central Singapore, Singapore, 119074
        • National University Hospital ( Site 0095)
      • Singapore, Central Singapore, Singapore, 169610
        • National Cancer Centre Singapore ( Site 0097)
      • Singapore, Central Singapore, Singapore, 258499
        • Oncocare Cancer Centre ( Site 0096)
  • South Korea
      • Incheon, South Korea, 21565
        • Gachon University Gil Medical Center ( Site 0087)
      • Seoul, South Korea, 02841
        • Korea University Anam Hospital ( Site 0084)
      • Seoul, South Korea, 03080
        • Seoul National University Hospital -SNUH- ( Site 0080)
      • Seoul, South Korea, 03722
        • Severance Hospital Yonsei University Health System ( Site 0081)
      • Seoul, South Korea, 05505
        • Asan Medical Center ( Site 0082)
      • Seoul, South Korea, 06273
        • Gangnam Severance Hospital ( Site 0088)
      • Seoul, South Korea, 07061
        • SMG-SNU BORAMAE Medical Center ( Site 0086)
    • Jeonranamdo
      • Hwasun Gun, Jeonranamdo, South Korea, 58128
        • Chonnam National University Hwasun Hospital ( Site 0083)
    • Kyonggi-do
      • Seongnam-si, Kyonggi-do, South Korea, 13620
        • Seoul National University Bundang Hospital ( Site 0085)
    • Taegu-Kwangyokshi
      • Daegu, Taegu-Kwangyokshi, South Korea, 41404
        • Kyungpook National University Chilgok Hospital ( Site 0089)
  • Taiwan
      • New Taipei City, Taiwan, 235
        • Taipei Medical University Shuang Ho Hospital ( Site 0068)
      • Tainan, Taiwan, 704
        • National Cheng Kung University Hospital ( Site 0067)
      • Taipei, Taiwan, 10002
        • National Taiwan University Hospital ( Site 0063)
      • Taipei, Taiwan, 104
        • Mackay Memorial Hospital ( Site 0065)
      • Taipei, Taiwan, 11259
        • Koo Foundation Sun Yat-Sen Cancer Center ( Site 0066)
      • Taoyuan District, Taiwan, 333
        • Chang Gung Medical Foundation. Linkou ( Site 0064)
  • Ukraine
    • Dnipropetrovsk Oblast
      • Dnipro, Dnipropetrovsk Oblast, Ukraine, 49102
        • City Clinical Hosp.4 of DCC ( Site 0325)
      • Kryviy Rih, Dnipropetrovsk Oblast, Ukraine, 50048
        • MI Kryvyi Rih Oncology Dispensary of Dnipropetrovsk Regional Council ( Site 0589)
    • Ivano-Frankivsk Oblast
      • Ivano-Frankivsk, Ivano-Frankivsk Oblast, Ukraine, 76018
        • Ivano-Frankivsk Regional Oncology Clinical Dispensary ( Site 0321)
    • Kharkivs’ka Oblast’
      • Kharkiv, Kharkivs’ka Oblast’, Ukraine, 61070
        • Communal non profit enterprise Regional Clinical Oncology Center ( Site 0591)
    • Kyivska Oblast
      • Kyiv, Kyivska Oblast, Ukraine, 03022
        • National Cancer Institute of the MoH of Ukraine ( Site 0319)
      • Kyiv, Kyivska Oblast, Ukraine, 03115
        • Kyiv City Clinical Oncology Center ( Site 0590)
  • United Kingdom
      • Manchester, United Kingdom, M20 4BX
        • The Christie NHS Foundation Trust ( Site 0397)
    • Bristol, City of
      • Bristol, Bristol, City of, United Kingdom, BS2 8ED
        • University Hospitals Bristol NHS Foundation Trust ( Site 0407)
    • Dundee City
      • Dundee, Dundee City, United Kingdom, DD1 9SY
        • Ninewells Hospital and Medical School ( Site 0406)
    • London, City of
      • London, London, City of, United Kingdom, NW3 2QG
        • Royal Free London NHS Foundation Trust ( Site 0403)
      • London, London, City of, United Kingdom, SW3 6JJ
        • The Royal Marsden Foundation Trust ( Site 0405)
      • London, London, City of, United Kingdom, W2 1NY
        • Imperial College Healthcare NHS Trust ( Site 0402)
    • Surrey
      • Sutton, Surrey, United Kingdom, SM2 5PT
        • Royal Marsden NHS Foundation Trust ( Site 0400)
  • United States
    • California
      • Duarte, California, United States, 91010
        • City of Hope ( Site 0005)
    • Connecticut
      • New Haven, Connecticut, United States, 06520
        • Yale Cancer Center ( Site 0016)
    • District of Columbia
      • Washington D.C., District of Columbia, United States, 20007
        • Georgetown University ( Site 0015)
    • Illinois
      • Chicago, Illinois, United States, 60611
        • Northwestern University - Robert H. Lurie Comprehensive Cancer Center ( Site 0018)
      • Chicago, Illinois, United States, 60637
        • The University of Chicago Medical Center ( Site 0004)
    • New York
      • Buffalo, New York, United States, 14263
        • Roswell Park Cancer Institute ( Site 0001)
      • New York, New York, United States, 10016
        • Laura and Isaac Perlmutter Cancer Center at NYU Langone Health ( Site 0019)
      • New York, New York, United States, 10065
        • Memorial Sloan Kettering ( Site 0024)
      • New York, New York, United States, 10065
        • Weill Cornell Medical Center ( Site 0023)
      • Rochester, New York, United States, 14642
        • University of Rochester ( Site 0011)
    • Pennsylvania
      • Philadelphia, Pennsylvania, United States, 19111
        • Fox Chase Cancer Center ( Site 0006)
      • Philadelphia, Pennsylvania, United States, 19140
        • Temple University Hospital ( Site 0026)
    • Utah
      • Salt Lake City, Utah, United States, 84112
        • University of Utah, Huntsman Cancer Institute ( Site 0012)
    • Virginia
      • Fairfax, Virginia, United States, 22031
        • Virginia Cancer Specialists, PC ( Site 0010)

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Has previously untreated localized gastric or GEJ adenocarcinoma as defined by T3 or greater primary lesion or the presence of any positive nodes - N+ (clinical nodes) without evidence of metastatic disease.
  • Plans to proceed to surgery following pre-operative chemotherapy based on standard staging studies per local practice.
  • Is willing to provide tissue from a tumor lesion at baseline and at time of surgery.
  • Has an Eastern Cooperative Oncology Group (ECOG) performance status score of 0 to 1 within 3 days prior to the first dose of study treatment.
  • Has adequate organ function.
  • Male participants of childbearing potential must agree to use an adequate method of contraception for the course of the study through 180 days after the last dose of chemotherapy.
  • Female participants of childbearing potential must be willing to use an adequate method of contraception for the course of the study through 180 days after the last dose of chemotherapy or through 120 days after the last dose of pembrolizumab, whichever is greater.
  • Has life expectancy of greater than 6 months.

Exclusion Criteria:

  • Has a history of (non-infectious) pneumonitis that required steroids or has current pneumonitis.
  • Has an active infection requiring systemic therapy.
  • Is currently participating in or has participated in a trial of an investigational agent or has used an investigational device within 4 weeks prior to the first dose of study treatment.
  • Has received prior therapy with an anti-programmed cell death protein-1 (anti-PD-1), anti-programmed cell death-ligand 1 (anti-PD-L1), or anti-PD-L2 agent or with an agent directed to another stimulatory or co-inhibitory T-cell receptor (i.e., cytotoxic T-lymphocyte-associated protein 4 [CTLA-4], tumor necrosis factor receptor superfamily member 4 [OX-40], necrosis factor receptor superfamily member 9 [CD137]) or has previously participated in a MSD pembrolizumab (MK-3475) clinical study.
  • Has received prior systemic anti-cancer therapy including investigational agents for the current malignancy.
  • Has a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy (in dosing exceeding 10 mg daily of prednisone equivalent) or any other form of immunosuppressive therapy within 14 days prior the first dose of study treatment.
  • Has a known additional malignancy that is progressing or has required active treatment within the past 5 years. Note: Participants with basal cell carcinoma of the skin, squamous cell carcinoma of the skin, or carcinoma in situ that have undergone potentially curative therapy are not excluded.
  • Has a known severe hypersensitivity (≥ Grade 3) to pembrolizumab, its active substance and/or any of its excipients, or to any of the study chemotherapy agents and/or to any of their excipients.
  • Has an active autoimmune disease that has required systemic treatment in past 2 years.
  • Has a known history of human immunodeficiency virus (HIV) infection.
  • Has a known history of Hepatitis B or known active Hepatitis C virus infection.
  • Has a known history of active tuberculosis (TB).
  • Female participants who are pregnant or breastfeeding or expecting to conceive children within the projected duration of the study, starting with the screening visit through180 days after the last dose of chemotherapy or through 120 days after the last dose of pembrolizumab, whichever is greater.
  • Male participants who are expecting to father children within the projected duration of the study, starting with the screening visit through 180 days after the last dose of chemotherapy.
  • Has had an allogenic tissue/solid organ transplant.
  • Has received a live vaccine within 30 days prior to the first dose of study treatment.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Pembrolizumab+FLOT Cohort

FLOT=docetaxel+oxaliplatin+5FU+leucovorin (calcium folinate). Neoadjuvant: Prior to surgery, participants receive 3 cycles of pembrolizumab 200 mg via IV infusion on Day 1 Q3W PLUS docetaxel 50 mg/m^2 via IV infusion, oxaliplatin 85 mg/m^2 via IV infusion, 5FU 2600 mg/m^2 via IV infusion, and leucovorin (calcium folinate) 200 mg/m^2 via IV infusion Q2W (on Days 1 and 15 of Cycle 1; Day 8 of Cycle 2, and Day 1 of Cycle 3, for 4 administrations).

Adjuvant: 4 to 10 weeks postsurgery, participants receive 3 cycles of pembrolizumab 200 mg via IV infusion Day 1 Q3W PLUS docetaxel 50 mg/m^2, oxaliplatin 85 mg/m^2, 5FU 2600 mg/m^2, and leucovorin 200 mg/m^2 Q2W (on Days 1 and 15 of Cycle 1; Day 8 of Cycle 2, and Day 1 of Cycle 3, for 4 administrations), followed by pembrolizumab monotherapy 200 mg via IV infusion on Day 1 Q3W for up to 11 additional cycles.
Biological: Pembrolizumab
IV infusion
Other Names:
  • MK-3475
  • KEYTRUDA®
Drug: Docetaxel
IV infusion
Other Names:
  • TAXOTERE®
Drug: 5-fluorouracil
IV infusion
Other Names:
  • 5FU
  • ADRUCIL®
Drug: Oxaliplatin
IV infusion
Other Names:
  • ELOXATIN®
Drug: Leucovorin
IV infusion
Other Names:
  • WELLCOVORIN®
Placebo Comparator: Placebo+FLOT Cohort

Neoadjuvant: Prior to surgery, participants receive 3 cycles of placebo (normal saline solution) via IV infusion on Day 1 Q3W PLUS docetaxel 50 mg/m^2 via IV infusion, oxaliplatin 85 mg/m^2 via IV infusion, 5FU 2600 mg/m^2 via IV infusion, and leucovorin 200 mg/m^2 via IV infusion Q2W (on Days 1 and 15 of Cycle 1; Day 8 of Cycle 2, and Day 1 of Cycle 3, for 4 administrations).

Adjuvant: 4 to 10 weeks postsurgery, participants receive 3 cycles of placebo via IV infusion on Day 1 Q3W PLUS docetaxel 50 mg/m^2 via IV infusion, oxaliplatin 85 mg/m^2 via IV infusion, 5FU 2600 mg/m^2 via IV infusion, and leucovorin 200 mg/m^2 via IV infusion Q2W (on Days 1 and 15 of Cycle 1; Day 8 of Cycle 2, and Day 1 of Cycle 3, for 4 administrations), followed by placebo monotherapy via IV infusion on Day 1 Q3W for up to 11 additional cycles.
Drug: Docetaxel
IV infusion
Other Names:
  • TAXOTERE®
Drug: Placebo
IV infusion
Other Names:
  • Normal saline solution
Drug: 5-fluorouracil
IV infusion
Other Names:
  • 5FU
  • ADRUCIL®
Drug: Oxaliplatin
IV infusion
Other Names:
  • ELOXATIN®
Drug: Leucovorin
IV infusion
Other Names:
  • WELLCOVORIN®
Experimental: Pembrolizumab + XP/FP

XP=cisplatin+capecitabine and FP=cisplatin+5-fluorouracil. Neoadjuvant: Prior to surgery, participants receive 3 cycles of pembrolizumab 200 mg via intravenous (IV) infusion on Day 1 of each 3-week cycle (Q3W) PLUS cisplatin 80 mg/m^2 via IV infusion on Day 1 Q3W and capecitabine 1000 mg/m^2 via oral tablets twice each day (BID) on Days 1 to 14 of each 3-week cycle OR cisplatin 80 mg/m^2 IV infusion on Day 1 Q3W and 5-fluorouracil (5FU) 800 mg/m^2 continuous IV infusion on Days 1 to 5 of each 3-week cycle.

Adjuvant: 4 to 10 weeks post-surgery, participants receive 3 cycles of pembrolizumab 200 mg IV infusion on Day 1 Q3W PLUS cisplatin 80 mg/m^2 IV infusion on Day 1 Q3W and capecitabine 1000 mg/m^2 via oral tablets BID on Days 1 to 14 of each 3-week cycle OR cisplatin 80 mg/m^2 IV infusion on Day 1 Q3W and 5FU 800 mg/m^2 continuous IV infusion on Days 1 to 5 of each 3-week cycle, followed by pembrolizumab monotherapy 200 mg IV infusion on Day 1 Q3W for up to 11 additional cycles.
Biological: Pembrolizumab
IV infusion
Other Names:
  • MK-3475
  • KEYTRUDA®
Drug: Cisplatin
IV infusion
Other Names:
  • PLATINOL®
Drug: Capecitabine
Oral tablets
Other Names:
  • XELODA®
Drug: 5-fluorouracil
IV infusion
Other Names:
  • 5FU
  • ADRUCIL®
Placebo Comparator: Placebo + XP/FP

Neoadjuvant: Prior to surgery, participants receive 3 cycles of placebo (normal saline solution) via IV infusion on Day 1 Q3W PLUS cisplatin 80 mg/m^2 via IV infusion on Day 1 Q3W and capecitabine 1000 mg/m^2 via oral tablets BID on Days 1 to 14 of each 3-week cycle OR cisplatin 80 mg/m^2 via IV infusion on Day 1 Q3W and 5FU 800 mg/m^2 via continuous IV infusion on Days 1 to 5 of each 3-week cycle.

Adjuvant: 4 to 10 weeks post-surgery, participants receive 3 cycles of placebo via IV infusion on Day 1 Q3W PLUS cisplatin 80 mg/m^2 via IV infusion on Day 1 Q3W and capecitabine 1000 mg/m^2 via oral tablets BID on Days 1 to 14 of each 3-week cycle OR cisplatin 80 mg/m^2 via IV infusion on Day 1 Q3W and 5FU 800 mg/m^2 via continuous IV infusion on Days 1 to 5 of each 3-week cycle, followed by placebo monotherapy via IV infusion on Day 1 Q3W for up to 11 additional cycles.
Drug: Placebo
IV infusion
Other Names:
  • Normal saline solution
Drug: Cisplatin
IV infusion
Other Names:
  • PLATINOL®
Drug: Capecitabine
Oral tablets
Other Names:
  • XELODA®
Drug: 5-fluorouracil
IV infusion
Other Names:
  • 5FU
  • ADRUCIL®

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Event-free Survival (EFS) Per Response Criteria in Solid Tumors Version 1.1 (RECIST 1.1) - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment Arms
Time Frame: Up to approximately 75 months
EFS was based on RECIST 1.1 as assessed by the investigator and was defined as the time from randomization to the first of the following events: radiographic disease progression per RECIST 1.1; local or distant recurrence as assessed by computer tomography (CT) scan or biopsy if indicated (for participants who were disease free after surgery); clinical progression as evidenced by peritoneal carcinomatosis confirmed by preoperative laparoscopy or laparotomy (for participants who were confirmed to be free of peritoneal involvement by laparoscopy at screening); or death due to any cause. A second primary malignancy, or radiographic progressive disease (PD) during the neoadjuvant phase that does not preclude successful surgery (i.e., disease free after surgery), were not considered EFS events.
Up to approximately 75 months
Pathological Complete Response (pathCR) Rate - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment Arms
Time Frame: Up to approximately 9 weeks following completion of neoadjuvant treatment (up to Study Week 18)
PathCR rate was defined as the percentage of participants having a pathCR based on central review. pathCR was defined as no invasive disease within an entirely submitted and evaluated gross lesion, and histologically negative nodes. The percentage of participants having pathCR was presented for the Pembrolizumab+XP/FP and Placebo+XP/FP treatment arms.
Up to approximately 9 weeks following completion of neoadjuvant treatment (up to Study Week 18)
Overall Survival (OS) - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment Arms
Time Frame: Up to approximately 75 months
OS was defined as the time from randomization to death due to any cause. OS was presented for the Pembrolizumab+XP/FP and Placebo+XP/FP treatment arms.
Up to approximately 75 months
Number of Participants Who Experienced One or More Adverse Events (AEs) - Pembrolizumab+FLOT and Placebo+FLOT Cohorts
Time Frame: Up to approximately 70 months
An AE was defined as any untoward medical occurrence in a participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment. The number of participants who experience at least one AE was presented for the Pembrolizumab+FLOT and Placebo+FLOT Cohorts.
Up to approximately 70 months
Number of Participants Who Discontinued Study Treatment Due to an AE - Pembrolizumab+FLOT and Placebo+FLOT Cohorts
Time Frame: Up to approximately 17 months
An AE was defined as any untoward medical occurrence in a participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment. The number of participants who discontinued study treatment due to an AE was presented for the Pembrolizumab+FLOT and Placebo+FLOT Cohorts.
Up to approximately 17 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Number of Participants Who Experienced One or More Adverse Events (AEs) - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment Arms Separately and in Combination With the Pembrolizumab+FLOT and Placebo+FLOT Cohorts
Time Frame: Up to approximately 89 months
An AE was defined as any untoward medical occurrence in a participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment. The number of participants who experienced at least one AE was presented for the Pembrolizumab+XP/FP and Placebo+XP/FP treatment arms separately and in combination with the Pembrolizumab+FLOT and Placebo+FLOT Cohorts.
Up to approximately 89 months
Number of Participants Who Discontinued Study Treatment Due to an AE - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment Arms Separately and in Combination With the Pembrolizumab+FLOT and Placebo+FLOT Cohorts
Time Frame: Up to approximately 17 months
An AE was defined as any untoward medical occurrence in a participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment. The number of participants who discontinued study treatment due to an AE was presented for the Pembrolizumab+XP/FP and Placebo+XP/FP treatment arms separately and in combination with the Pembrolizumab+FLOT and Placebo+FLOT Cohorts.
Up to approximately 17 months
Disease-free Survival (DFS) Per Response Criteria in Solid Tumors Version 1.1 (RECIST 1.1) - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment Arms
Time Frame: Up to approximately 75 months
DFS was defined as the time from post-surgery baseline scan until the first occurrence of local or distant recurrence or death from any cause and was based on RECIST 1.1 as assessed by the investigator.
Up to approximately 75 months
Overall Survival (OS) - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment Arms in Combination With the Pembrolizumab+FLOT and Placebo+FLOT Cohorts
Time Frame: Up to approximately 75 months
OS was defined as the time from randomization to death due to any cause. OS was presented for the Pembrolizumab+XP/FP and Placebo+XP/FP treatment arms in combination with the Pembrolizumab+FLOT and Placebo+FLOT Cohorts.
Up to approximately 75 months
Event-free Survival (EFS) Per Response Criteria in Solid Tumors Version 1.1 (RECIST 1.1) - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment Arms in Combination With the Pembrolizumab+FLOT and Placebo+FLOT Cohorts
Time Frame: Up to approximately 75 months
EFS was based on RECIST 1.1 as assessed by the investigator and was defined as the time from randomization to the first of the following events: radiographic disease progression per RECIST 1.1; local or distant recurrence as assessed by CT scan or biopsy if indicated (for participants who were disease free after surgery); clinical progression as evidenced by peritoneal carcinomatosis confirmed by preoperative laparoscopy or laparotomy (for participants who were confirmed to be free of peritoneal involvement by laparoscopy at screening); or death due to any cause. A second primary malignancy, or radiographic progressive disease (PD) during the neoadjuvant phase that does not preclude successful surgery (i.e., disease free after surgery), were not considered EFS events.
Up to approximately 75 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Merck Sharp & Dohme LLC

Investigators

  • Study Director: Medical Director, Merck Sharp & Dohme LLC

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

October 9, 2017

Primary Completion (Actual)

February 16, 2024

Study Completion (Actual)

April 23, 2025

Study Registration Dates

First Submitted

July 17, 2017

First Submitted That Met QC Criteria

July 17, 2017

First Posted (Actual)

July 18, 2017

Study Record Updates

Last Update Posted (Actual)

March 9, 2026

Last Update Submitted That Met QC Criteria

February 13, 2026

Last Verified

February 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 3475-585
  • MK-3475-585 (Other Identifier: MSD)
  • 173786 (Registry Identifier: JAPIC)
  • KEYNOTE-585 (Other Identifier: MSD)
  • PHRR200226-002534 (Registry Identifier: PHRR Research Registration)
  • 2023-509595-42-00 (Registry Identifier: EU CT)
  • 2023-509595-42 (EudraCT Number)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

https://trialstransparency.msdclinicaltrials.com/pdf/ProcedureAccessClinicalTrialData.pdf

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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