NCT03221426 · OUTCOME

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

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) · Source last updated 2026-03-09

Results reported by the registry submitting party. Population, time horizon, units and missing values must be read together.

Measure: MEDIAN
Unit: Months
Interval / dispersion: 95% Confidence Interval
Time frame: Up to approximately 75 months

What was measured

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.

Analysis 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.

Groups in this outcome

Pembrolizumab + XP/FP

XP=cisplatin+capecitabine and FP=cisplatin+5-fluorouracil. Neoadjuvant: Prior to surgery, participants received 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) 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 received 3 cycles of 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 800 mg/m\^2 via continuous IV infusion on Days 1 to 5 of each 3-week cycle, followed by pembrolizumab monotherapy 200 mg via IV infusion on Day 1 Q3W for up to 11 additional cycles.

Placebo + XP/FP

Neoadjuvant: Prior to surgery, participants received 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 received 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.

Group identifiers and denominators belong to this outcome only. They may differ in another outcome or in safety reporting.

Analysis denominator · Participants

Group	Source count
Pembrolizumab + XP/FP	402
Placebo + XP/FP	402

Reported measurements

Source class 1

Values in Months · Interval/dispersion: 95% Confidence Interval
Group	Value	Spread	Lower	Upper	Comment
Pembrolizumab + XP/FP	71.8	Not reported	52.5	NA	NA = Upper limit was not reached at time of data cut-off due to insufficient number of participants with an event
Placebo + XP/FP	55.7	Not reported	41.7	NA	NA = Upper limit was not reached at time of data cut-off due to insufficient number of participants with an event

Source statistical analyses

Group order, estimate direction, methods and comments are retained. No treatment ranking is inferred.

ci Lower Limit
0.71
ci Num Sides
TWO_SIDED
ci Pct Value
95
ci Upper Limit
1.06
estimate Comment
Cox regression model with Efron's method of tie handling with treatment as a covariate stratified by geographic region (Asia vs. Non-Asia) and tumor staging (II vs. III vs. IVa)
group Ids
OG000
OG001
non Inferiority Type
SUPERIORITY
p Value
0.07503
p Value Comment
One-sided p-value based on log-rank test stratified by geographic region (Asia vs. Non-Asia) and tumor staging (II vs. III vs. IVa)
param Type
Hazard Ratio (HR)
param Value
0.86
statistical Method
Log Rank

Complete source fields

analyses

ci Lower Limit
0.71
ci Num Sides
TWO_SIDED
ci Pct Value
95
ci Upper Limit
1.06
estimate Comment
Cox regression model with Efron's method of tie handling with treatment as a covariate stratified by geographic region (Asia vs. Non-Asia) and tumor staging (II vs. III vs. IVa)
group Ids
OG000
OG001
non Inferiority Type
SUPERIORITY
p Value
0.07503
p Value Comment
One-sided p-value based on log-rank test stratified by geographic region (Asia vs. Non-Asia) and tumor staging (II vs. III vs. IVa)
param Type
Hazard Ratio (HR)
param Value
0.86
statistical Method
Log Rank

classes

categories
measurements
comment
NA = Upper limit was not reached at time of data cut-off due to insufficient number of participants with an event
group Id
OG000
lower Limit
52.5
upper Limit
NA
value
71.8
comment
NA = Upper limit was not reached at time of data cut-off due to insufficient number of participants with an event
group Id
OG001
lower Limit
41.7
upper Limit
NA
value
55.7

denoms

counts
group Id
OG000
value
402
group Id
OG001
value
402
units
Participants

description

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.

dispersion Type

95% Confidence Interval

groups

description
XP=cisplatin+capecitabine and FP=cisplatin+5-fluorouracil. Neoadjuvant: Prior to surgery, participants received 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) 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 received 3 cycles of 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 800 mg/m\^2 via continuous IV infusion on Days 1 to 5 of each 3-week cycle, followed by pembrolizumab monotherapy 200 mg via IV infusion on Day 1 Q3W for up to 11 additional cycles.
id
OG000
title
Pembrolizumab + XP/FP
description
Neoadjuvant: Prior to surgery, participants received 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 received 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.
id
OG001
title
Placebo + XP/FP

param Type

MEDIAN

population Description

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

reporting Status

POSTED

time Frame

Up to approximately 75 months

title

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

type

PRIMARY

unit Of Measure

Months

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Preserved source evidence · Not medical advice