A Study of Atezolizumab in Combination With Carboplatin + Paclitaxel or Carboplatin + Nab-Paclitaxel Compared With Carboplatin + Nab-Paclitaxel in Participants With Stage IV Squamous Non-Small Cell Lung Cancer (NSCLC) [IMpower131]

OS in the in the Teff Population

OS is defined as the time between the date of randomization and date of death from any cause in the in the Teff Population.

Time frame: Up to approximately 39 months after first participant enrolled

PFS as Determined by the Investigator Using RECIST v1.1 in the Teff Population

PFS is defined as the time between the date of randomization and the date of first documented disease progression or death, whichever occurs first, in the Teff Population.

Time frame: Up to approximately 30 months after first participant enrolled

PFS as Determined by the Investigator Using RECIST v1.1 in the Tumor Cell (TC) 2/3 or Tumor-Infiltrating Immune Cell (IC) 2/3 Population

PFS is defined as the time between the date of randomization and the date of first documented disease progression or death, whichever occurs first, in the Tumor Cell (TC) 2/3 or Tumor-Infiltrating Immune Cell (IC) 2/3 Population.

Time frame: Up to approximately 30 months after first participant enrolled

PFS as Determined by the Investigator Using RECIST v1.1 in the TC1/2/3 or IC1/2/3 Population

PFS is defined as the time between the date of randomization and the date of first documented disease progression or death, whichever occurs first, in the TC1/2/3 or IC1/2/3 Population.

Time frame: Up to approximately 30 months after first participant enrolled

OS in the TC2/3 or IC2/3 Population

OS is defined as the time between the date of randomization and date of death from any cause, in the TC2/3 or IC2/3 Population.

Time frame: Up to approximately 39 months after first participant enrolled

OS in the TC1/2/3 or IC1/2/3 Population

OS is defined as the time between the date of randomization and date of death from any cause in the TC1/2/3 or IC1/2/3 Population.

Time frame: Up to approximately 39 months after first participant enrolled

Percentage of Participants With Objective Response as Determined by the Investigator Using RECIST v1.1 in the ITT Population

Proportion of participants with an objective response (CR or PR) in the ITT population.

Time frame: Up to approximately 30 months after first participant enrolled

Duration of Response as Determined by the Investigator Using RECIST v1.1 in the ITT Population

Duration of response is defined as the time from the first documented objective response to documented PD or death from any cause, whichever occurred first, in the ITT Population.

Time frame: Up to approximately 30 months after first participant enrolled

Event Free Rate at 1 and 2 Years in the ITT Population

Event free rate at 1 and 2 years is defined as the proportion of participants alive at 1 and 2 years after randomization estimated using Kaplan-Meier (KM) methodology for the ITT population.

Time frame: 1 and 2 years

Time to Deterioration (TTD) in Patient-reported Lung Cancer Symptoms Using EORTC QLQ-C30 Symptom Subscales in the ITT Population

TTD in Patient-reported Lung Cancer Symptoms Using EORTC QLQ-C30 Symptom Subscales in the ITT Population. The EORTC QLQ-C30 is a validated and reliable self-report measure that consists of 30 questions that assess five aspects of patient functioning (physical, emotional, role, cognitive, and social), three symptom scales (fatigue, nausea and vomiting, pain), global health/quality of life, and six single items (dyspnea, insomnia, appetite loss, constipation, diarrhea, and financial difficulties). EORTC scales and single-item measures will be linearly transformed so that each score has a range of 0-100. A high score for a functional scale represents a high or healthy level of functioning, and a high score for the global health status and HRQoL represents a high HRQoL; however, a high score for a symptom scale or item represents a high level of symptomatology or problems.

Time frame: Up to approximately 30 months after first participant enrolled

TTD in Patient-reported Lung Cancer Symptoms Using EORTC QLQ-LC13 Symptom Subscales in the ITT Population

TTD was documented for a 3-symptom composite endpoint using the following EORTC QLQ-LC13 symptom scores: cough, chest pain, and dyspnea multi--item scale. In this instance, symptom deterioration will be determined as a \>= 10-point increase above baseline in any of the listed symptom scores, whichever occurs first (cough, chest pain, and dyspnea multi-item scale). Confirmed clinically meaningful symptom deterioration will need to be held for the original symptom; a \>= 10-point increase above baseline in a symptom score must be held for at least two consecutive assessments or an initial\>=10-point increase above baseline followed by death within 3 weeks from the last assessment. A \>= 10-point change in the EORTC scale score is perceived by patients as clinically significant.

Time frame: Up to approximately 30 months after the first participant enrolled

Change From Baseline in Patient-reported Lung Cancer Symptoms Score Using the SILC Scale Symptom Severity Score in the ITT Population

Change from baseline per SILC scale will be analyzed for each lung cancer symptoms scores. SILC questionnaire comprises 3 individual symptoms \& are scored at individual symptom level, thus have a dyspnea score, chest pain score, \& cough score. There are a total of 9 questions in SILC questionnaire, each question has a minimum value of 0 \& maximum value of 4. Each individual symptom score is calculated as average of responses for symptom items. 'Chest pain' score is mean of question 1 \& 2, 'Cough' score is mean of question 3 \& 4 and 'Dyspnea' score is mean of question 5 to 9 in SILC questionnaire. An increase in score is suggestive of a worsening in symptomology. A score change of ≥0.3 points for dyspnea \& cough symptom scores is considered to be clinically significant; whereas a score change of ≥0.5 points for chest pain score is considered to be clinically significant. (Note: PD=progression of disease)

Time frame: Baseline up to approximately 30 months after first participant enrolled

PFS as Determined by the Investigator Using RECIST v1.1 in the ITT Population (Arm A and Arm B)

PFS is defined as the time between the date of randomization and the date of first documented disease progression or death, whichever occurs first, in the ITT Population Arm A and Arm B.

Time frame: Up to approximately 30 months after first participant enrolled

OS in the ITT Population (Arm A and Arm B)

OS is defined as the time between the date of randomization and date of death from any cause in the ITT Population, Arm A and Arm B.

Time frame: Up to approximately 39 months after first participant enrolled

Percentage of Participants With Adverse Events

Percentage of participants with at least one adverse event.

Time frame: Up to approximately 68 months after first participant enrolled

Percentage of Participants With Anti-therapeutic Antibody (ATA) Response to Atezolizumab

Percentage of participants with Anti-therapeutic Antibody (ATA) response to atezolizumab.

Time frame: Up to approximately 30 months after first participant enrolled

Maximum Observed Serum Atezolizumab Concentration (Cmax)

Maximum observed serum atezolizumab concentration (Cmax). The predose samples will be collected on the same day of treatment administration. The infusion duration of atezolizumab will be of 30-60 minutes.

Time frame: Cycle 1 Day 1 and Cycle 3 Day 1 (Cycle length = 21 days)

Minimum Observed Serum Atezolizumab Concentration (Cmin)

Minimum observed serum atezolizumab concentration (Cmin). The predose samples will be collected on the same day of treatment administration.

Time frame: Predose on Day 1 of Cycles 1-4, 8, 16, every 8 cycle thereafter (up to 30 months), at treatment discontinuation (up to 30 months), and at 120 days after the last dose of atezolizumab (up to approximately 30 months, each cycle is 21 days)

Plasma Concentrations for Paclitaxel

Plasma concentrations for paclitaxel.

Time frame: Prior to infusion (within same day of treatment administration), 5-10 minutes before the end of infusion, and 1 hour after the end of infusion (infusion duration 180 minutes) on Day 1 of Cycles 1 and 3 (each cycle is 21 days)

Plasma Concentrations for Nab-Paclitaxel

Plasma concentrations for nab-paclitaxel.

Time frame: Prior to infusion (within same day of treatment administration), 5-10 minutes before the end of infusion, and 1 hour after the end of infusion (infusion duration 30 minutes) on Day 1 of Cycles 1 and 3 (each cycle is 21 days)

Plasma Concentrations for Carboplatin

Plasma concentrations for carboplatin.

Time frame: Prior to infusion (within same day of treatment administration), 5-10 minutes before the end of infusion, and 1 hour after the end of infusion (infusion duration 15 to 30 minutes) on Day 1 of Cycles 1 and 3 (each cycle is 21 days)