This is a study of pembrolizumab (MK-3475) for advanced gastric or gastroesophageal junction adenocarcinoma; pembrolizumab will be given as monotherapy to participants who have had previous treatment or who are treatment-naïve; pembrolizumab will also be evaluated as combination therapy with cisplatin and 5-Fluorouracil (5-FU) or (Japan only) capecitabine in treatment-naïve participants. The primary study hypothesis is that pembrolizumab will provide a clinically meaningful Overall Response Rate (ORR).
This study will have 3 cohorts. In Cohort 1, participants who have received at least two prior therapies for their advanced disease will receive monotherapy with pembrolizumab. In Cohort 2, participants who have not received any previous therapy for their disease will receive pembrolizumab in combination with cisplatin and 5-FU or (Japan only) capecitabine. In Cohort 3, participants who have not received any previous therapy and who have programmed death ligand 1 (PD-L1)-positive tumors will receive pembrolizumab monotherapy.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
318
IV infusion
IV infusion
IV infusion
oral tablets
Number of Participants Experiencing Adverse Events (AEs)
An AE is defined as any untoward medical occurrence in a participant administered study drug and which does not necessarily have to have a causal relationship with the study drug. The number of participants who experienced at least one AE is presented. Per protocol, the number of participants who experienced at least one AE during first course pembrolizumab treatment is presented.
Time frame: Up to approximately 65 months
Number of Participants Discontinuing Study Drug Due to AEs
An AE was defined as any untoward medical occurrence in a participant administered study drug and which does not necessarily have to have a causal relationship with the study drug. The number of participants who discontinued study drug due to an AE is presented. Per protocol, the number of participants who discontinued drug during first course pembrolizumab treatment is presented.
Time frame: Up to approximately 52 months
Objective Response Rate (ORR) For All Participants in Cohorts 1 and 3
The Objective Response Rate (ORR) was defined as the percentage of participants in the analysis population who had a Complete Response (CR: Disappearance of all target lesions) or Partial Response (PR: At least a 30% decrease in the sum of diameters of target lesions) per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1) as assessed by central radiology review. The percentage of all participants (regardless of programmed death-ligand 1 \[PD-L1\] tumor status) in Cohorts 1 and 3 who had a CR or PR during first course pembrolizumab treatment per protocol, is presented.
Time frame: Up to approximately 75 months
Objective Response Rate For PD-L1 Positive Participants in Cohorts 1 and 3
The ORR was defined as the percentage of participants in the analysis population who had a CR or PR (CR: Disappearance of all target lesions; PR: At least a 30% decrease in the sum of diameters of target lesions) per RECIST 1.1, as assessed by central radiology review. The percentage of all participants in Cohorts 1 and 3 with PD-L1+ tumor status who experienced a CR or PR during first course pembrolizumab treatment per protocol, is presented. Note: All participants in Cohort 3 had a PD-L1-positive tumor status.
Time frame: Up to approximately 75 months
Objective Response Rate (ORR) For All Participants in Cohort 2
The Objective Response Rate (ORR) was defined as the percentage of participants in the analysis population who had a Complete Response (CR: Disappearance of all target lesions) or Partial Response (PR: At least a 30% decrease in the sum of diameters of target lesions) per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1) as assessed by central radiology review. The percentage of all participants (regardless of PD-L1 tumor status) in Cohort 2 who had a CR or PR during first course pembrolizumab treatment per protocol, is presented.
Time frame: Up to approximately 75 months
Objective Response Rate For PD-L1 Positive Participants in Cohort 2
The ORR was defined as the percentage of participants in the analysis population who had a CR or PR (CR: Disappearance of all target lesions; PR: At least a 30% decrease in the sum of diameters of target lesions) per RECIST 1.1, as assessed by central radiology review. The percentage of participants in Cohort 2 with PD-L1+ tumor status who experienced a CR or PR during first course pembrolizumab treatment per protocol, is presented.
Time frame: Up to approximately 75 months
Duration of Response (DOR) For All Participants
Duration of Response (DOR) was defined as the time from first documented evidence of CR or PR (CR: Disappearance of all target lesions; PR: At least a 30% decrease in the sum of diameters of target lesions) per RECIST 1.1, based on central imaging vendor assessment, until disease progression (PD) or death, whichever occurred first. PD is defined as ≥20% increase in the sum of diameters of target lesions. In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of ≥5 mm. The appearance of one or more new lesions is also considered PD. Participants who had not progressed or died at the time of analysis were censored at the date of their last tumor assessment. The DOR for all participants (regardless of PD-L1 tumor status) during first course pembrolizumab treatment per protocol, is presented.
Time frame: Up to approximately 75 months
Duration of Response For PD-L1 Positive Participants
DOR was defined as the time from first documented evidence of CR or PR (CR: Disappearance of all target lesions; PR: At least a 30% decrease in the sum of diameters of target lesions) per RECIST 1.1, based on central imaging vendor assessment, until disease progression (PD) or death, whichever occurred first. PD is defined as ≥20% increase in the sum of diameters of target lesions. In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of ≥5 mm. The appearance of one or more new lesions is also considered PD. Participants who had not progressed or died at the time of analysis were censored at the date of their last tumor assessment. The DOR for only PD-L1 positive participants during first course pembrolizumab treatment per protocol, is presented. Note: All participants in Cohort 3 had a PD-L1-positive tumor status.
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Time frame: Up to approximately 75 months
Progression-Free Survival (PFS) For All Participants
Progression-Free Survival (PFS) was defined as the time from randomization to the first documented disease progression, or death due to any cause, whichever occurred first. Per RECIST 1.1, progressive disease was defined as at least a 20% increase in the sum of diameters of target lesions, taking as reference the smallest sum on study. In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of at least 5 mm. The appearance of one or more new lesions was also considered progression. The PFS for all participants (regardless of PD-L1 tumor status) during first course pembrolizumab treatment per protocol, is presented.
Time frame: Up to approximately 75 months
Progression-Free Survival For PD-L1 Positive Participants
PFS was defined as the time from randomization to the first documented disease progression, or death due to any cause, whichever occurred first. Per RECIST 1.1, progressive disease was defined as at least a 20% increase in the sum of diameters of target lesions, taking as reference the smallest sum on study. In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of at least 5 mm. The appearance of one or more new lesions was also considered progression. The PFS for only PD-L1 positive participants during first course pembrolizumab treatment per protocol, is presented. Note: All participants in Cohort 3 had a PD-L1-positive tumor status.
Time frame: Up to approximately 75 months
Overall Survival (OS) For All Participants
Overall Survival (OS) was defined as the time from randomization to death due to any cause. Participants without documented death at the time of the final analysis were censored at the date of the last follow-up. The OS for all participants (regardless of PD-L1 tumor status) during first course pembrolizumab treatment per protocol, is presented.
Time frame: Up to approximately 75 months
Overall Survival For PD-L1 Positive Participants
OS was defined as the time from randomization to death due to any cause. Participants without documented death at the time of the final analysis were censored at the date of the last follow-up. The OS for only PD-L1 positive participants during first course pembrolizumab treatment per protocol, is presented. Note: All participants in Cohort 3 had a PD-L1-positive tumor status.
Time frame: Up to approximately 75 months
Disease Control Rate (DCR) For All Participants
Disease Control Rate (DCR) was defined as the percentage of participants in the analysis population who had a CR or a PR (CR: Disappearance of all target lesions; PR: At least a 30% decrease in the sum of diameters of target lesions) or stable disease (SD); (SD: neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for progressive disease) for ≥6 months, (for Cohort 1 ≥2 months) as assessed by central radiology review. The percentage of all participants (regardless of PD-L1 tumor status) who had a CR or PR or SD during first course pembrolizumab treatment per protocol, is presented.
Time frame: Up to approximately 75 months
Disease Control Rate For PD-L1 Positive Participants
DCR was defined as the percentage of participants in the analysis population who had a CR or a PR (CR: Disappearance of all target lesions; PR: At least a 30% decrease in the sum of diameters of target lesions) or stable disease (SD); (SD: neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for progressive disease) for ≥6 months, (for Cohort 1 ≥2 months) as assessed by central radiology review. The percentage of participants with PD-L1+ tumor status who experienced a CR or PR or SD during first course pembrolizumab treatment per protocol, is presented. Note: All participants in Cohort 3 had a PD-L1-positive tumor status.
Time frame: Up to approximately 75 months