A Study of Atezolizumab and Tiragolumab Compared With Durvalumab in Participants With Locally Advanced, Unresectable Stage III Non-Small Cell Lung Cancer (NSCLC)

Inclusion Criteria: * Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1 * Histologically or cytologically documented NSCLC with locally advanced, unresectable Stage III NSCLC of either squamous or non-squamous histology * Whole-body Positron Emission Tomography-Computed Tomography (PET-CT) scan, performed prior and within 42 days of the first dose of concurrent chemoradiotherapy (cCRT) * At least two prior cycles of platinum-based chemotherapy administered concurrently with radiotherapy (RT), which must be completed within 1 to 42 days prior to randomization in the study (one cycle of cCRT is defined as 21 or 28 days) * The radiotherapy (RT) component in the cCRT must have been at a total dose of radiation of 60 (±10 percent \[%\]) gray (Gy) (54 Gy to 66 Gy) administered by intensity modulated RT (preferred) or 3D-conforming technique * No progression during or following concurrent platinum-based CRT * A known PD-L1 result * Life expectancy \>/= 12 weeks * Adequate hematologic and end-organ function * Female participants must be willing to avoid pregnancy for 90 days after the final dose of tiragolumab and 5 months after the final dose of atezolizumab, or for 3 months after the final dose of durvalumab * Male participants must remain abstinent or use a condom during the treatment period and for 90 days after the final dose of tiragolumab * Male participants must not donate sperm during the treatment period and for 90 days after the final dose of tiragolu…