A Study of Tiragolumab in Combination With Atezolizumab Compared With Placebo in Combination With Atezolizumab in Patients With Previously Untreated Locally Advanced Unresectable or Metastatic PD-L1-Selected Non-Small Cell Lung Cancer

Inclusion Criteria:

* Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1
* Histologically or cytologically documented locally advanced or recurrent NSCLC not eligible for curative surgery and/or definitive radiotherapy with or without chemoradiotherapy, or metastatic Stage IV non-squamous or squamous NSCLC
* No prior systemic treatment for metastatic NSCLC
* High tumor tissue PD-L1 expression
* Measurable disease per Response Evaluation Criteria in Solid Tumors, Version 1.1 (RECIST v1.1)
* Adequate hematologic and end-organ function
* For participants enrolled in the extended China enrollment phase: current resident of mainland China or Taiwan and of Chinese ancestry.

Exclusion Criteria:

* Known mutation in the EGFR gene or an ALK fusion oncogene
* Symptomatic, untreated, or actively progressing central nervous system metastases
* Active or history of autoimmune disease or immune deficiency
* History of idiopathic pulmonary fibrosis, organizing pneumonia, drug-induced pneumonitis, or idiopathic pneumonitis, or evidence of active pneumonitis
* Malignancies other than NSCLC within 5 years, with the exception of those with a negligible risk of metastasis or death treated with expected curative outcome
* Severe infection within 4 weeks prior to initiation of study treatment
* Positive test result for human immunodeficiency virus (HIV)
* Active hepatitis B or hepatitis C
* Treatment with investigational therapy within 28 days prior to initiation of study treatment
* Prior treatment with CD137 agonists or immune checkpoint blockade therapies, anti-CTLA-4, anti-TIGIT, anti-PD-1, and anti-PD-L1 therapeutic antibodies
* Treatment with systemic immunostimulatory agents within 4 weeks or 5 drug elimination half-lives prior to initiation of study treatment.