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]

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.

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

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.

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.

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.

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.

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.

Proportion of participants with an objective response (CR or PR) 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.

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.

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.

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.

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)

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.

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.

Percentage of participants with at least one adverse event.

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

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.

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

Plasma concentrations for paclitaxel.

Plasma concentrations for nab-paclitaxel.

Plasma concentrations for carboplatin.