Tislelizumab in Combination With Chemotherapy as First-Line Treatment in Adults With Inoperable, Locally Advanced or Metastatic Gastric, or Gastroesophageal Junction Carcinoma

Overall survival (OS) is defined as the time from the date of randomization to the date of death due to any cause. Median OS was estimated using the Kaplan-Meier method.

Time frame: From randomization up to the primary analysis data cut-off date of 8 October 2021; Median (range) time on follow-up was 11.8 (0.1 - 33.4) months.

Population: The PD-L1-Positive Analysis Set included all randomized participants whose tumors were PD-L1 positive (defined as PD-L1 TAP score ≥ 5%)

Overall survival (OS) is defined as the time from the date of randomization to the date of death due to any cause. Median OS was estimated using the Kaplan-Meier method.

Time frame: From randomization up to the final efficacy analysis data cut-off date of 28 February 2023; Median (range) time on follow-up was 13.2 (0.1 - 50.1) months.

Population: The Intent-to-Treat (ITT) Analysis Set included all randomized participants.

The EORTC QLQ-30 contains 30 questions that incorporate 5 functional scales (physical functioning, role functioning, emotional functioning, cognitive functioning, and social functioning), 1 global health status scale, 3 symptom scales (fatigue, nausea and vomiting, and pain), and 6 single items (dyspnea, insomnia, appetite loss, constipation, diarrhea, and financial difficulties). The participant answers questions about their health during the past week. There are 28 questions answered on a 4-point scale where 1 = Not at all (best) and 4 = Very Much (worst) and 2 global health quality of life (QOL) questions answered on a 7-point scale where 1 = Very poor and 7 = Excellent. Raw scores are transformed to a 0 to 100 scale via linear transformation. The fatigue symptom scale includes 3 items and ranges from 0 to 100, where higher scores indicate a higher level of symptoms.

Time frame: Baseline and Cycles 4 and 6

Population: Participants in the ITT Analysis Set who completed the EORTC QLQ-C30 at baseline; participants with available data at baseline and the relevant postbaseline visit are included in the analysis at each time point.

The EORTC QLQ-30 contains 30 questions that incorporate 5 functional scales (physical functioning, role functioning, emotional functioning, cognitive functioning, and social functioning), 1 global health status scale, 3 symptom scales (fatigue, nausea and vomiting, and pain), and 6 single items (dyspnea, insomnia, appetite loss, constipation, diarrhea, and financial difficulties). The participant answers questions about their health during the past week. There are 28 questions answered on a 4-point scale where 1 = Not at all (best) and 4 = Very Much (worst) and 2 global health quality of life (QOL) questions answered on a 7-point scale where 1 = Very poor and 7 = Excellent. Raw scores are transformed to a 0 to 100 scale via linear transformation. Higher scores in GHS and functional scales indicate better quality of life.

Time frame: Baseline and Cycles 4 and 6

Population: Participants in the ITT Analysis Set who completed the EORTC QLQ-C30 at baseline; participants with available data at baseline and the relevant postbaseline visit are included in the analysis at each time point.

EORTC-QLQ-STO22 is a 22-item questionnaire developed to assess QoL of gastric cancer participants. It consists of 5 multi-item subscales: Dysphagia/odynophagia (4 items), Pain/discomfort (3 items), Dietary restrictions (5 items), Upper gastro-intestinal (GI) symptoms (3 items), Specific emotional problems (3 items) and 4 single items. Each question is answered on a scale from 0 (Not at all) to 4 (Very Much), where lower scores indicate fewer symptoms/better QoL. Raw scores were transformed to a scale from 0 to 100, where lower scores indicate better QoL. The QLQ-STO22 Index score is the mean of the 6 domain scores and 4 single items.

Time frame: Baseline and Cycles 4 and 6

Population: Participants in the ITT Analysis Set who completed the EORTC QLQ-STO22 at baseline; participants with available data at baseline and the relevant postbaseline visit are included in the analysis at each time point.

The EQ-5D-5L measures health outcomes using a VAS to record a participant's self-rated health on a scale from 0 to 100, where 100 is 'the best health you can imagine' and 0 is 'the worst health you can imagine.' A higher score indicates better health outcomes.

Time frame: Baseline and Cycles 4 and 6

Population: Participants in the ITT Analysis Set who completed the EQ-5D-5L at baseline; participants with available data at baseline and the relevant postbaseline visit are included in the analysis at each time point.

Clinical benefit rate is defined as the percentage of participants who achieved a confirmed complete response, partial response, or durable stable disease assessed by the Investigator per RECIST v1.1. CR: Disappearance of all target and non-target lesions and no new lesions. Any pathological lymph nodes must have reduction in short axis to \< 10 mm. PR: At least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum diameters, persistence of one or more nontarget lesion(s) and/or maintenance of tumor marker level above the normal limits. Durable SD: Stable disease for ≥ 24 weeks.

Time frame: Response was assessed every 6 weeks for the first 48 weeks and every 9 weeks thereafter; up to the final efficacy analysis data cut-off date of 28 February 2023; Median (range) time on follow-up was 13.2 (0.1 - 50.1) months.

Population: PD-L1 Positive Analysis Set

Clinical benefit rate is defined as the percentage of participants who achieved a confirmed complete response, partial response, or durable stable disease assessed by the Investigator per RECIST v1.1. CR: Disappearance of all target and non-target lesions and no new lesions. Any pathological lymph nodes must have reduction in short axis to \< 10 mm. PR: At least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum diameters, persistence of one or more nontarget lesion(s) and/or maintenance of tumor marker level above the normal limits. Durable SD: Stable disease for ≥ 24 weeks.

Time frame: Response was assessed every 6 weeks for the first 48 weeks and every 9 weeks thereafter; up to the final efficacy analysis data cut-off date of 28 February 2023; Median (range) time on follow-up was 13.2 (0.1 - 50.1) months.

Population: ITT Analysis Set

Disease Control Rate is defined as the percentage of participants who had confirmed CR, PR, or stable disease (SD) assessed by the investigator and the investigator per RECIST v1.1. Investigators conducted assessments of radiological tumor response by CT or MRI per RECIST version 1.1 about every six weeks during the first 48 weeks of the study and every nine weeks thereafter. CR: Disappearance of all target and non-target lesions and no new lesions. Any pathological lymph nodes must have reduction in short axis to \< 10 mm. PR: At least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum diameters, persistence of one or more nontarget lesion(s) and/or maintenance of tumor marker level above the normal limits. SD: Neither sufficient shrinkage in size of lesions to qualify for PR nor sufficient increase to qualify for PD, and no new lesions.

Time frame: Response was assessed every 6 weeks for the first 48 weeks and every 9 weeks thereafter; up to the final efficacy analysis data cut-off date of 28 February 2023; Median (range) time on follow-up was 13.2 (0.1 - 50.1) months.

Population: PD-L1 Positive Analysis Set

Disease Control Rate is defined as the percentage of participants who had confirmed CR, PR, or stable disease (SD) assessed by the investigator per RECIST v1.1. Investigators conducted assessments of radiological tumor response by CT or MRI per RECIST version 1.1 about every six weeks during the first 48 weeks of the study and every nine weeks thereafter. CR: Disappearance of all target and non-target lesions and no new lesions. Any pathological lymph nodes must have reduction in short axis to \< 10 mm. PR: At least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum diameters, persistence of one or more nontarget lesion(s) and/or maintenance of tumor marker level above the normal limits. SD: Neither sufficient shrinkage in size of lesions to qualify for PR nor sufficient increase to qualify for PD, and no new lesions.

Time frame: Response was assessed every 6 weeks for the first 48 weeks and every 9 weeks thereafter; up to the final efficacy analysis data cut-off date of 28 February 2023; Median (range) time on follow-up was 13.2 (0.1 - 50.1) months.

Population: ITT Analysis Set

DOR is defined as the time from the first determination of an objective response assessed by the investigator per RECIST v1.1, until the first documentation of progression or death, whichever occurred first. Progressive disease (PD): At least a 20% increase in the size of target lesions, taking as reference the smallest size on study, with an absolute increase of at least 5 mm, unequivocal progression of existing non-target lesions, or any new lesions.

Time frame: Response was assessed every 6 weeks for the first 48 weeks and every 9 weeks thereafter; up to the final efficacy analysis data cut-off date of 28 February 2023; Median (range) time on follow-up was 13.2 (0.1 - 50.1) months.

Population: Participants in the PD-L1 Positive Analysis Set with an objective response

DOR is defined as the time from the first determination of an objective response assessed by the investigator per RECIST v1.1, until the first documentation of progression or death, whichever occurred first. Progressive disease (PD): At least a 20% increase in the size of target lesions, taking as reference the smallest size on study, with an absolute increase of at least 5 mm, unequivocal progression of existing non-target lesions, or any new lesions.

Time frame: Response was assessed every 6 weeks for the first 48 weeks and every 9 weeks thereafter; up to the final efficacy analysis data cut-off date of 28 February 2023; Median (range) time on follow-up was 13.2 (0.1 - 50.1) months.

Population: Participants in the ITT Analysis Set with an objective response

An AE is defined as any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of study drugs, whether related to study drugs or not. An SAE is any untoward medical occurrence that, at any dose met any of the following criteria: * Resulted in death * Was life-threatening * Required hospitalization or prolongation of existing hospitalization * Resulted in disability/incapacity * Was a congenital anomaly/birth defect * Was considered a significant medical AE by the Investigator based on medical judgement.

Time frame: From first dose of study drug to 30 days after last dose or the initiation of a new anticancer therapy, whichever occurred first, up to the end of study; maximum treatment duration was 59.3 months in Tislelizumab and 56.8 months in the Placebo group.

Population: The Safety Analysis Set included all participants who received ≥ 1 dose of study drug

ORR is defined as the percentage of participants whose best overall response is complete response (CR) or partial response (PR) per Response Evaluation Criteria in Solid Tumors v1.1 assessed by the investigator. Investigators conducted assessments of radiological tumor response by computed tomography (CT) or magnetic resonance imaging (MRI) per RECIST version 1.1 about every six weeks during the first 48 weeks of the study and every nine weeks thereafter. CR: Disappearance of all target and non-target lesions and no new lesions. Any pathological lymph nodes must have reduction in short axis to \< 10 mm. PR: At least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum diameters, persistence of one or more nontarget lesion(s) and/or maintenance of tumor marker level above the normal limits.

Time frame: Response was assessed every 6 weeks for the first 48 weeks and every 9 weeks thereafter; up to the final efficacy analysis data cut-off date of 28 February 2023; Median (range) time on follow-up was 13.2 (0.1 - 50.1) months.

Population: PD-L1 Positive Analysis Set

ORR is defined as the percentage of participants whose best overall response is complete response (CR) or partial response (PR) per Response Evaluation Criteria in Solid Tumors v1.1 assessed by the investigator. Investigators conducted assessments of radiological tumor response by computed tomography (CT) or magnetic resonance imaging (MRI) per RECIST version 1.1 about every six weeks during the first 48 weeks of the study and every nine weeks thereafter. CR: Disappearance of all target and non-target lesions and no new lesions. Any pathological lymph nodes must have reduction in short axis to \< 10 mm. PR: At least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum diameters, persistence of one or more nontarget lesion(s) and/or maintenance of tumor marker level above the normal limits.

Time frame: Response was assessed every 6 weeks for the first 48 weeks and every 9 weeks thereafter; up to the final efficacy analysis data cut-off date of 28 February 2023; Median (range) time on follow-up was 13.2 (0.1 - 50.1) months.

Population: Intent-to-Treat (ITT) Analysis Set

Progression-free survival is defined as the time from the date of randomization to the date of the first objectively documented tumor progression assessed by the investigator according to Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1, or death, whichever occurred first. Median PFS was estimated using the Kaplan-Meier method.

Time frame: From randomization up to the final efficacy analysis data cut-off date of 28 February 2023; Median (range) time on follow-up was 13.2 (0.1 - 50.1) months.

Population: PD-L1 Positive Analysis Set

Progression-free survival is defined as the time from the date of randomization to the date of the first objectively documented tumor progression assessed by the investigator according to Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1, or death, whichever occurred first. Median PFS was estimated using the Kaplan-Meier method.

Time frame: From randomization up to the final efficacy analysis data cut-off date of 28 February 2023; Median (range) time on follow-up was 13.2 (0.1 - 50.1) months.

Population: Intent-to-Treat Analysis Set

Time to response is defined as the time from randomization to the first determination of an objective response per RECIST version 1.1 as assessed by the investigator.

Time frame: From randomization up to the final efficacy analysis data cut-off date of 28 February 2023; Median (range) time on follow-up was 13.2 (0.1 - 50.1) months.

Population: Participants in the PD-L1 Positive Analysis Set with an objective response

Time to response is defined as the time from randomization to the first determination of an objective response per RECIST version 1.1 as assessed by the investigator.

Time frame: From randomization up to the final efficacy analysis data cut-off date of 28 February 2023; Median (range) time on follow-up was 13.2 (0.1 - 50.1) months.

Population: Participants in the ITT Analysis Set with an objective response