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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)-China Extension

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)

Status
Completed
Phases
Phase 3
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT04882241
Enrollment
120
Registered
2021-05-11
Start date
2020-07-29
Completion date
2025-04-23
Last updated
2026-03-06

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Gastric Cancer, Gastroesophageal Junction Cancer

Keywords

Programmed Cell Death-1 (PD1, PD-1), Programmed Death-Ligand 1 (PDL1, PD-L1)

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 Chinese adults with gastric and gastroesophageal junction (GEJ) adenocarcinoma. No formal hypothesis testing will be done.

Detailed description

The China extension study will include participants previously enrolled in China in the global study for MK-3475-585 (NCT03221426) plus those enrolled during the China extension enrollment period. A total of approximately 120 Chinese participants will be enrolled.

Interventions

BIOLOGICALPembrolizumab

IV infusion

DRUGPlacebo

IV infusion

DRUGCisplatin

IV infusion

DRUGCapecitabine

Oral tablets

DRUG5-fluorouracil

IV infusion

DRUGDocetaxel

IV infusion

DRUGOxaliplatin

IV infusion

DRUGLeucovorin

IV infusion

Sponsors

Merck Sharp & Dohme LLC
Lead SponsorINDUSTRY

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)

Masking description

Double-blind study

Eligibility

Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No

Inclusion criteria

* Has previously untreated localized gastric or gastroesophageal junction (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.

Design outcomes

Primary

MeasureTime frameDescription
Event-free Survival (EFS) Per Response Criteria in Solid Tumors Version 1.1 (RECIST 1.1) - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment ArmsUp to approximately 42 monthsEFS is based on RECIST 1.1 as assessed by the investigator and is 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 are disease free after surgery); clinical progression as evidenced by peritoneal carcinomatosis confirmed by preoperative laparoscopy or laparotomy (for participants who are 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), are not considered EFS events.
Pathological Complete Response (pathCR) Rate - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment ArmsUp to approximately 9 weeks following completion of neoadjuvant treatment (up to Study Week 18)PathCR rate is defined as the percentage of participants having a pathCR. pathCR is defined as no invasive disease within an entirely submitted and evaluated gross lesion, and histologically negative nodes.
Overall Survival (OS) - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment ArmsUp to approximately 42 monthsOS is defined as the time from randomization to death due to any cause. OS is presented for the Pembrolizumab+XP/FP and Placebo+XP/FP treatment arms.
Number of Participants Who Experience One or More Adverse Events (AEs) - Pembrolizumab+FLOT and Placebo+FLOT CohortsUp to approximately 42 monthsAn AE is 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 FLOT cohort was not enrolled in China per specifications in the protocol Supplemental Statistical Analysis Plan (sSAP) amendment and no data were collected for the FLOT cohort in China.
Number of Participants Who Discontinue Study Treatment Due to an Adverse Event (AE) - Pembrolizumab+FLOT and Placebo+FLOT CohortsUp to approximately 17 monthsAn AE is 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 FLOT cohort was not enrolled in China per specifications in the protocol sSAP amendment and no data were collected for the FLOT cohort in China.

Secondary

MeasureTime frameDescription
Number of Participants Who Experience 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 CohortsUp to approximately 42 monthsAn AE is 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 is presented for Pembrolizumab+XP/FP and Placebo+XP/FP treatment arms. The FLOT cohort was not enrolled in China per specifications in the protocol Supplemental Statistical Analysis Plan (sSAP) amendment and no data were collected for the FLOT cohort in China. There is no FLOT cohort in China to combine with XP/FP arms.
Number of Participants Who Discontinue Study Treatment Due to an Adverse Event (AE) - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment Arms Separately and in Combination With the Pembrolizumab+FLOT and Placebo+FLOT CohortsUp to approximately 23 monthsAn AE is 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 discontinue study treatment due to an AE will be presented for Pembrolizumab+XP/FP and Placebo+XP/FP treatment arms. The FLOT cohort was not enrolled in China per specifications in the protocol sSAP amendment and no data were collected for the FLOT cohort in China. There is no FLOT cohort in China to combine with XP/FP arms.
Disease-free Survival (DFS) Per Response Criteria in Solid Tumors Version 1.1 (RECIST 1.1) - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment ArmsUp to approximately 42 monthsDFS is defined as the time from post-surgery baseline scan until the first occurrence of local/distant recurrence or death from any cause and is based on RECIST 1.1 as assessed by the investigator.
Overall Survival (OS) - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment Arms in Combination With the Pembrolizumab+FLOT and Placebo+FLOT CohortsUp to approximately 42 monthsOS is defined as the time from randomization to death due to any cause. The FLOT cohort was not enrolled in China per specifications in the protocol sSAP amendment and no data were collected for the FLOT cohort in China. There is no FLOT cohort in China to combine with XP/FP arms.
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 CohortsUp to approximately 42 monthsEFS is based on RECIST 1.1 as assessed by the investigator and is 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 are disease free after surgery); clinical progression as evidenced by peritoneal carcinomatosis confirmed by preoperative laparoscopy or laparotomy (for participants who are 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), are not considered EFS events. The FLOT cohort was not enrolled in China per specifications in the protocol sSAP amendment and no data were collected for the FLOT cohort in China. There is no FLOT cohort in China to combine with XP/FP arms.

Countries

China

Contacts

STUDY_DIRECTORMedical Director

Merck Sharp & Dohme LLC

Participant flow

Pre-assignment details

120 Chinese participants were enrolled. 5 participants were randomized in the global portion of the study (NCT03221426) and 115 in the China extension portion. The FLOT cohort was not enrolled in China per specifications in the protocol Supplemental Statistical Analysis Plan (sSAP) amendment and no data were collected for the FLOT cohort in China.

Participants by arm

ArmCount
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 via IV infusion on Day 1 Q3W and 5-fluorouracil (5FU) via continuous IV infusion on Days 1 to 5 of each 3-week cycle. Adjuvant: 4 to 10 weeks post-surgery, participants receive pembrolizumab 200 mg 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 via continuous IV infusion on Days 1 to 5 of each 3-week cycle for up to 3 cycles.
59
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 via continuous IV infusion on Days 1 to 5 of each 3-week cycle. Adjuvant: 4 to 10 weeks post-surgery, participants receive 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 via continuous IV infusion on Days 1 to 5 of each 3-week cycle for up to 3 cycles.
61
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 pembrolizumab 200 mg via IV infusion Day 1 Q3W for up to 11 cycles 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.
0
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 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.
0
Total120

Baseline characteristics

CharacteristicTotalPlacebo + XP/FPPembrolizumab + FLOT CohortPembrolizumab + XP/FPPlacebo + FLOT Cohort
Age, Customized
Adults (between 18 and 64 years)
73 Participants35 Participants0 Participants38 Participants0 Participants
Age, Customized
From 65 to 84 years
47 Participants26 Participants0 Participants21 Participants0 Participants
Ethnicity (NIH/OMB)
Hispanic or Latino
0 Participants0 Participants0 Participants0 Participants0 Participants
Ethnicity (NIH/OMB)
Not Hispanic or Latino
120 Participants61 Participants0 Participants59 Participants0 Participants
Ethnicity (NIH/OMB)
Unknown or Not Reported
0 Participants0 Participants0 Participants0 Participants0 Participants
Geographic Region
Asia
120 Participants61 Participants0 Participants59 Participants0 Participants
Race (NIH/OMB)
American Indian or Alaska Native
0 Participants0 Participants0 Participants0 Participants0 Participants
Race (NIH/OMB)
Asian
120 Participants61 Participants0 Participants59 Participants0 Participants
Race (NIH/OMB)
Black or African American
0 Participants0 Participants0 Participants0 Participants0 Participants
Race (NIH/OMB)
More than one race
0 Participants0 Participants0 Participants0 Participants0 Participants
Race (NIH/OMB)
Native Hawaiian or Other Pacific Islander
0 Participants0 Participants0 Participants0 Participants0 Participants
Race (NIH/OMB)
Unknown or Not Reported
0 Participants0 Participants0 Participants0 Participants0 Participants
Race (NIH/OMB)
White
0 Participants0 Participants0 Participants0 Participants0 Participants
Sex: Female, Male
Female
25 Participants9 Participants0 Participants16 Participants0 Participants
Sex: Female, Male
Male
95 Participants52 Participants0 Participants43 Participants0 Participants
Tumor Staging
Stage II
15 Participants7 Participants0 Participants8 Participants0 Participants
Tumor Staging
Stage III
97 Participants48 Participants0 Participants49 Participants0 Participants
Tumor Staging
Stage IVa
8 Participants6 Participants0 Participants2 Participants0 Participants

Adverse events

Event typeEG000
affected / at risk
EG001
affected / at risk
deaths
Total, all-cause mortality
22 / 5922 / 61
other
Total, other adverse events
59 / 5961 / 61
serious
Total, serious adverse events
32 / 5930 / 61

Outcome results

Primary

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

EFS is based on RECIST 1.1 as assessed by the investigator and is 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 are disease free after surgery); clinical progression as evidenced by peritoneal carcinomatosis confirmed by preoperative laparoscopy or laparotomy (for participants who are 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), are not considered EFS events.

Time frame: Up to approximately 42 months

Population: The analysis population consisted of all randomized participants in the Pembrolizumab+XP/FP and Placebo+XP/FP treatment arms, as pre-specified per protocol.

ArmMeasureValue (MEDIAN)
Pembrolizumab + XP/FPEvent-free Survival (EFS) Per Response Criteria in Solid Tumors Version 1.1 (RECIST 1.1) - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment ArmsNA Months
Placebo + XP/FPEvent-free Survival (EFS) Per Response Criteria in Solid Tumors Version 1.1 (RECIST 1.1) - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment Arms36.5 Months
p-value: 0.3952895% CI: [0.5, 1.7]Log Rank
Primary

Number of Participants Who Discontinue Study Treatment Due to an Adverse Event (AE) - Pembrolizumab+FLOT and Placebo+FLOT Cohorts

An AE is 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 FLOT cohort was not enrolled in China per specifications in the protocol sSAP amendment and no data were collected for the FLOT cohort in China.

Time frame: Up to approximately 17 months

Population: The FLOT cohort was not enrolled in China per specifications in the protocol sSAP amendment and no data were collected for the FLOT cohort in China.

Primary

Number of Participants Who Experience One or More Adverse Events (AEs) - Pembrolizumab+FLOT and Placebo+FLOT Cohorts

An AE is 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 FLOT cohort was not enrolled in China per specifications in the protocol Supplemental Statistical Analysis Plan (sSAP) amendment and no data were collected for the FLOT cohort in China.

Time frame: Up to approximately 42 months

Population: The FLOT cohort was not enrolled in China per specifications in the protocol sSAP amendment and no data were collected for the FLOT cohort in China.

Primary

Overall Survival (OS) - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment Arms

OS is defined as the time from randomization to death due to any cause. OS is presented for the Pembrolizumab+XP/FP and Placebo+XP/FP treatment arms.

Time frame: Up to approximately 42 months

Population: The analysis population consisted of all randomized participants in the Pembrolizumab+XP/FP and Placebo+XP/FP treatment arms, as pre-specified per protocol.

ArmMeasureValue (MEDIAN)
Pembrolizumab + XP/FPOverall Survival (OS) - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment ArmsNA Months
Placebo + XP/FPOverall Survival (OS) - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment ArmsNA Months
p-value: 0.5290395% CI: [0.48, 2.22]Log Rank
Primary

Pathological Complete Response (pathCR) Rate - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment Arms

PathCR rate is defined as the percentage of participants having a pathCR. pathCR is defined as no invasive disease within an entirely submitted and evaluated gross lesion, and histologically negative nodes.

Time frame: Up to approximately 9 weeks following completion of neoadjuvant treatment (up to Study Week 18)

Population: The analysis population consisted of all randomized participants in the Pembrolizumab+XP/FP and Placebo+XP/FP treatment arms, as pre-specified per protocol.

ArmMeasureValue (NUMBER)
Pembrolizumab + XP/FPPathological Complete Response (pathCR) Rate - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment Arms6.8 Percentage of Participants
Placebo + XP/FPPathological Complete Response (pathCR) Rate - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment Arms4.9 Percentage of Participants
p-value: 0.3324495% CI: [-7.7, 12]Miettinen and Nurminen
Secondary

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

DFS is defined as the time from post-surgery baseline scan until the first occurrence of local/distant recurrence or death from any cause and is based on RECIST 1.1 as assessed by the investigator.

Time frame: Up to approximately 42 months

Population: The analysis population consisted of all randomized participants in the Pembrolizumab+XP/FP and Placebo+XP/FP treatment arms who had surgery, as pre-specified per protocol.

ArmMeasureValue (MEDIAN)
Pembrolizumab + XP/FPDisease-free Survival (DFS) Per Response Criteria in Solid Tumors Version 1.1 (RECIST 1.1) - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment ArmsNA Months
Placebo + XP/FPDisease-free Survival (DFS) Per Response Criteria in Solid Tumors Version 1.1 (RECIST 1.1) - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment Arms33.1 Months
p-value: 0.3463295% CI: [0.34, 2.05]Log Rank
Secondary

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

EFS is based on RECIST 1.1 as assessed by the investigator and is 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 are disease free after surgery); clinical progression as evidenced by peritoneal carcinomatosis confirmed by preoperative laparoscopy or laparotomy (for participants who are 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), are not considered EFS events. The FLOT cohort was not enrolled in China per specifications in the protocol sSAP amendment and no data were collected for the FLOT cohort in China. There is no FLOT cohort in China to combine with XP/FP arms.

Time frame: Up to approximately 42 months

Population: The FLOT cohort was not enrolled in China per specifications in the protocol sSAP amendment and no data were collected for the FLOT cohort in China. There is no FLOT cohort in China to combine with XP/FP arms.

Secondary

Number of Participants Who Discontinue Study Treatment Due to an Adverse Event (AE) - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment Arms Separately and in Combination With the Pembrolizumab+FLOT and Placebo+FLOT Cohorts

An AE is 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 discontinue study treatment due to an AE will be presented for Pembrolizumab+XP/FP and Placebo+XP/FP treatment arms. The FLOT cohort was not enrolled in China per specifications in the protocol sSAP amendment and no data were collected for the FLOT cohort in China. There is no FLOT cohort in China to combine with XP/FP arms.

Time frame: Up to approximately 23 months

Population: The analysis population consisted of all participants who received ≥1 dose of study treatment. The FLOT cohort was not enrolled in China per specifications in the protocol sSAP amendment and no data were collected for the FLOT cohort in China. There is no FLOT cohort in China to combine with XP/FP arms.

ArmMeasureValue (COUNT_OF_PARTICIPANTS)
Pembrolizumab + XP/FPNumber of Participants Who Discontinue Study Treatment Due to an Adverse Event (AE) - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment Arms Separately and in Combination With the Pembrolizumab+FLOT and Placebo+FLOT Cohorts12 Participants
Placebo + XP/FPNumber of Participants Who Discontinue Study Treatment Due to an Adverse Event (AE) - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment Arms Separately and in Combination With the Pembrolizumab+FLOT and Placebo+FLOT Cohorts8 Participants
Secondary

Number of Participants Who Experience 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

An AE is 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 is presented for Pembrolizumab+XP/FP and Placebo+XP/FP treatment arms. The FLOT cohort was not enrolled in China per specifications in the protocol Supplemental Statistical Analysis Plan (sSAP) amendment and no data were collected for the FLOT cohort in China. There is no FLOT cohort in China to combine with XP/FP arms.

Time frame: Up to approximately 42 months

Population: The analysis population consisted of all participants who received ≥1 dose of study treatment. The FLOT cohort was not enrolled in China per specifications in the protocol sSAP amendment and no data were collected for the FLOT cohort in China. There is no FLOT cohort in China to combine with XP/FP arms.

ArmMeasureValue (COUNT_OF_PARTICIPANTS)
Pembrolizumab + XP/FPNumber of Participants Who Experience 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 Cohorts59 Participants
Placebo + XP/FPNumber of Participants Who Experience 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 Cohorts61 Participants
Secondary

Overall Survival (OS) - Pembrolizumab+XP/FP and Placebo+XP/FP Treatment Arms in Combination With the Pembrolizumab+FLOT and Placebo+FLOT Cohorts

OS is defined as the time from randomization to death due to any cause. The FLOT cohort was not enrolled in China per specifications in the protocol sSAP amendment and no data were collected for the FLOT cohort in China. There is no FLOT cohort in China to combine with XP/FP arms.

Time frame: Up to approximately 42 months

Population: The FLOT cohort was not enrolled in China per specifications in the protocol sSAP amendment and no data were collected for the FLOT cohort in China. There is no FLOT cohort in China to combine with XP/FP arms.

Source: ClinicalTrials.gov · Data processed: Mar 7, 2026