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)
Overview
- Phase
- Phase 3
- Intervention
- Pembrolizumab
- Conditions
- Gastric Cancer
- Sponsor
- Merck Sharp & Dohme LLC
- Enrollment
- 1007
- Locations
- 171
- Primary Endpoint
- 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
- Status
- Completed
- Last Updated
- last month
Overview
Brief Summary
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.
Investigators
Eligibility Criteria
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.
Arms & Interventions
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.
Intervention: Pembrolizumab
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.
Intervention: Cisplatin
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.
Intervention: Capecitabine
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.
Intervention: 5-fluorouracil
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.
Intervention: Placebo
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.
Intervention: Cisplatin
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.
Intervention: Capecitabine
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.
Intervention: 5-fluorouracil
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.
Intervention: Pembrolizumab
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.
Intervention: 5-fluorouracil
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.
Intervention: Docetaxel
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.
Intervention: Oxaliplatin
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.
Intervention: Leucovorin
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.
Intervention: Placebo
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.
Intervention: 5-fluorouracil
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.
Intervention: Docetaxel
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.
Intervention: Oxaliplatin
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.
Intervention: Leucovorin
Outcomes
Primary Outcomes
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.
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.
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.
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.
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.
Secondary Outcomes
- 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(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(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(Up to approximately 75 months)
- 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(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(Up to approximately 17 months)