OS was defined as the time between the date of randomization and the date of death from any cause. Participants were censored at the date they were last known to be alive. Median OS time was calculated using Kaplan-Meier (KM) method. Hazard ratio (HR) and the corresponding Confidence Interval (CI) were estimated in a stratified Cox proportional hazards model for distribution of OS in each randomized arm. Interim analysis (Primary Endpoint) was planned to occur after at least 196 deaths, with the actual analysis occurring at 199 deaths.

All randomized participants

The overall survival rate is the probability that a participant will be alive at 6, 12, and 18 months following randomization. Overall survival was defined as the time between the date of randomization and the date of death as a result of any cause. Survival rates were determined via Kaplan-Meier estimates.

All randomized participants

The number of participants who died from any cause was reported for each arm. Interim analysis (Primary Endpoint) was planned to occur after at least 196 deaths, with the actual analysis occurring at 199 deaths.

All randomized participants

ORR was defined as the percentage of all randomized participants whose Best Overall Response (BOR) was a confirmed Complete Response (CR) or Partial Response (PR). BOR was defined as the best investigator-assessed response designation, recorded between the date of randomization and the date of objectively documented progression per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1) or the date of subsequent anti-cancer therapy (excluding on-treatment palliative radiotherapy of non-target bone lesions or Central Nervous System (CNS) lesions), whichever occurred first. CR = Disappearance of all target lesions. Any pathological lymph nodes (whether target or non-target) 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. CIs were computed using the Clopper and Pearson method.

All randomized participants

Time to Response (TTR) for participants demonstrating a response (either CR or PR) was defined as the time from the date of randomization to the date of the first confirmed response. CR = Disappearance of all target lesions. Any pathological lymph nodes (whether target or non-target) 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.

All confirmed responders (participants demonstrating CR or PR)

DOR was defined as the time from the date of first confirmed response to the date of the first documented tumor progression (per RECIST v1.1), as determined by the investigator, or death due to any cause, whichever occurred first. DOR was evaluated only for confirmed responders (i.e. participants with confirmed CR or PR). CR = Disappearance of all target lesions. Any pathological lymph nodes (whether target or non-target) 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. Participants who neither progressed nor died were censored on the date of their last evaluable tumor assessment.

All confirmed responders (participants demonstrating CR or PR)

PFSR was defined as the percentage of participants who did not experience disease progression or death from any cause at a given time point following randomization. Progression was assessed by investigators according to RECIST v1.1. Participants who did not progress or die were censored on the date of their last evaluable tumor assessment. Participants who started any subsequent anti-cancer therapy (including on-treatment palliative radiation therapy (RT) of non-target bone lesions or CNS lesions) without a prior reported progression were to be censored at the last evaluable tumor assessment prior to or on initiation of the subsequent anti-cancer therapy.

All randomized participants

PFS was defined as the time from the date of randomization to the date of the first documented tumor progression as determined by the investigator per RECIST v1.1 criteria, or death due to any cause. Participants underwent radiographic tumor assessments every 6 weeks (+/- 5 days) from week 9 (+/- 5 days) for the first year on treatment, then every 12 weeks after the first year on treatment until documented disease progression. The PFS curves were estimated using KM method. Two-sided 95% CI for median PFS were computed by Brookmeyer and Crowley method (using log-log transformation). Participants who did not progress or die were censored on the date of their last evaluable tumor assessment. Participants who started any subsequent anti-cancer therapy (including on-treatment palliative RT of non-target bone lesions or CNS lesions) without a prior reported progression were to be censored at the last evaluable tumor assessment prior to or on initiation of the subsequent anti-cancer therapy.

All randomized participants

Disease-related symptom improvement rate by Week 12 was defined as the percentage of randomized participants who had a 10 point or greater decrease from baseline in average symptom burden index score at any time between randomization and Week 12. The participant portion of the Lung Cancer Symptom Scale (LCSS) consisted of 6 symptom-specific questions that addressed cough, dyspnea, fatigue, pain, hemoptysis, and anorexia, plus 3 summary items on symptom distress, interference with activity level, and global health-related Quality of Life (QoL). The scores range from 0 to 100, with 0 representing the best possible score and 100 being the worst possible score. The average symptom burden index score at each assessment was defined as the mean of the 6 symptom-specific questions of the LCSS. 95% CIs were computed using Clopper-Pearson Method.

All randomized participants

OS was measured in months for all randomized participants grouped by their baseline PD-L1 expression level. PD-L1 expression was defined as the percent of disease tumor cells demonstrating plasma membrane PD-L1 staining of any intensity using an immunohistochemistry (IHC) assay. OS was defined as the time between the date of randomization and the date of death from any cause. Participants were censored at the date they were last known to be alive. Median OS time was calculated using Kaplan-Meier (KM) method.

All randomized participants

ORR was reported for all randomized participants grouped by their baseline PD-L1 expression level. ORR was defined as the percentage of all randomized participants whose Best Overall Response (BOR) was a confirmed Complete Response (CR) or Partial Response (PR). PD-L1 expression in participants was defined as the percent of disease tumor cells demonstrating plasma membrane PD-L1 staining of any intensity using an immunohistochemistry (IHC) assay. CR = Disappearance of all target lesions. Any pathological lymph nodes (whether target or non-target) 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. CIs were computed using the Clopper and Pearson method.

All randomized participants

PFS time was measured for all randomized participants grouped by their baseline PD-L1 expression levels. PFS was defined as the time from the date of randomization to the date of the first documented tumor progression as determined by the investigator per RECIST v1.1 criteria, or death due to any cause. The PFS curves were estimated using KM method. Participants who did not progress or die were censored on the date of their last evaluable tumor assessment. Participants who started subsequent anti-cancer therapy (including on-treatment palliative radiotherapy of non-target bone lesions or CNS lesions) without a prior reported progression were censored at the last evaluable tumor assessment prior to subsequent anti-cancer therapy.

All randomized participants

OS was defined as the time between the date of randomization and the date of death from any cause. Participants were censored at the date they were last known to be alive. Median OS time was calculated using Kaplan-Meier (KM) method. Hazard ratio (HR) and the corresponding Confidence Interval (CI) were estimated in a stratified Cox proportional hazards model for distribution of OS in each randomized arm. Survival follow-up analysis occurred at the end of the study.

All randomized participants

The overall survival rate is the probability that a participant will be alive at the specified timepoints following randomization. Overall survival was defined as the time between the date of randomization and the date of death as a result of any cause. Survival rates were determined via Kaplan-Meier estimates.

All randomized participants