A Study of Tiragolumab in Combination With Atezolizumab Plus Pemetrexed and Carboplatin/Cisplatin Versus Pembrolizumab Plus Pemetrexed and Carboplatin/Cisplatin in Participants With Previously Untreated Advanced Non-Squamous Non-Small Cell Lung Cancer

Overall Survival (Phase 2)

Time frame: From randomization to death from any cause (up to approximately 5 years)

PFS as Determined by an Independent Review Facility (IRF) (Phase 3)

Time frame: From randomization to the first occurrence of disease progression or death from any cause, whichever occurs first (up to approximately 5 years)

Investigator-assessed PFS in Participants With PD-L1 Expression at TC ≥50% and TC ≥1% Cut-off, as Determined by Central Testing With Ventana PD-L1 (SP263) Assay (Phase 3)

Time frame: From randomization to the first occurrence of disease progression or death from any cause, whichever occurs first (up to approximately 5 years)

OS in Participants With PD-L1 Expression at TC ≥50% and TC ≥1% Cut-off, as Determined by Central Testing With Ventana PD-L1 (SP263) Assay (Phase 3)

Time frame: From randomization to death from any cause (up to approximately 5 years)

Investigator-Assessed PFS at 6 Months and 12 Months (Phase 3)

Time frame: 6 months, 12 months

OS Rate at 12 Months and 24 Months (Phase 3)

Time frame: 12 months, 24 months

Investigator-Assessed Confirmed ORR (Phase 3)

Time frame: Up to approximately 5 years

Investigator-Assessed Duration of Response (DOR) (Phase 2 and Phase 3)

Time frame: From first occurrence of a documented confirmed objective response to the first occurrence of disease progression or death from any cause, whichever occurs first (up to approximately 5 years)

Time to Confirmed Deterioration (TTCD) in Participant-Reported Physical Functioning and Global Health Status (GHS)/Quality of Life (QoL) as Measured by European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30 (Phase 2 and Phase 3)

TTCD using EORTC Quality-of-Life Questionnaire Core 30 (QLQ-C30) is an initial 10-point decrease in GHS and physical functioning from baseline that must be held for at least two consecutive assessments or an initial clinically meaningful decrease above baseline followed by death. EORTC QLQ-C30: a self-reported measure, consisting of 30 questions that assess 5 aspects of participants functioning (physical, emotional, role, cognitive and social), 3 symptom scales (fatigue, nausea/vomiting and pain), GHS and QoL, and 6 single items (dyspnea, insomnia, appetite loss, constipation, diarrhea and financial difficulties) with a recall period of the previous week. Functioning items are scored on a 4-point scale: 1=Not at all to 4=Very much, with higher score indicating worse outcome. Symptom items (GHS and QoL) are scored on a 7-point scale: 1=Very poor to 7=Excellent. Scores will be linearly transformed with a minimum score of 0 and maximum score of 100. Higher score indicates better outcome.

Time frame: Up to approximately 5 years

TTCD in Participant-Reported Lung Cancer Symptoms for Cough, Dyspnea, and Chest Pain, as Measured by EORTC QLQ-LC13 (Phase 2 and Phase 3)

TTCD using EORTC Quality-of-Life Questionnaire Lung Cancer Module (QLQ-LC13) is an initial 10-point increase in symptom score from baseline that must be held for at least two consecutive assessments or an initial clinically meaningful decrease above baseline followed by death. EORTC QLQ-LC13 consists of 13 lung cancer specific items and includes 11 disease-specific scales/items (dyspnea, coughing, hemoptysis, sore mouth, dysphagia, peripheral neuropathy, alopecia, pain in chest, pain in arm or shoulder, pain in other parts, pain medication). Each item is scored on a 4-point scale of 1=Not at all to 4=Very much. Scores will be linearly transformed to a score range of 0 to 100. Higher score indicates worsening of symptoms.

Time frame: Up to approximately 5 years

Percentage of Participants With Adverse Events (AEs) (Phase 2 and Phase 3)

Time frame: Up to approximately 5 years

Participants' Response to Side Effects of Treatment as Assessed by EORTC IL46 (Phase 2 and Phase 3)

EORTC Item List 46 (IL46) is a validated single-item question that assesses overall side effect impact. Each item is scored on a 4-point scale of 1=Not at all to 4=Very much. Scores will be linearly transformed to a score range of 0 to 100. Higher score indicates a worse outcome.

Time frame: Up to approximately 5 years

Serum Concentration of Tiragolumab (Phase 2 and Phase 3)

Time frame: Cycle 1 (each cycle=21 days), Day 1: predose, 0.5 hour (h) postdose; Cycles 2, 3, 4, 8, 12, 16, Day 1: predose and at treatment discontinuation (TD) visit (up to approximately 5 years)

Serum Concentration of Atezolizumab (Phase 2 and Phase 3)

Time frame: Cycle 1 (each cycle=21 days), Day 1: predose, 0.5 hour (h) postdose; Cycles 2, 3, 4, 8, 12, 16, Day 1: predose and at TD visit (up to approximately 5 years)

Percentage of Participants With Anti-Drug Antibodies (ADAs) to Tiragolumab (Phase 2 and Phase 3)

Time frame: Predose on Day 1 of Cycles (each cycle=21 days) 1, 2, 3, 4, 8, 12, 16 and at TD visit (up to approximately 5 years)

Percentage of Participants With ADAs to Atezolizumab (Phase 2 and Phase 3)

Time frame: Predose on Day 1 of Cycles (each cycle=21 days) 1, 2, 3, 4, 8, 12, 16 and at TD visit (up to approximately 5 years)