A Study of Carboplatin Plus Etoposide With or Without Atezolizumab in Participants With Untreated Extensive-Stage (ES) Small Cell Lung Cancer (SCLC)

Inclusion Criteria

• Histologically or cytologically confirmed ES-SCLC (per the Veterans Administration Lung Study Group [VALG] staging system)
• No prior systemic treatment for ES-SCLC
• Eastern Cooperative Oncology Group performance status of 0 or 1
• Measurable disease, as defined by RECIST v1.1
• Adequate hematologic and end organ function
• Treatment-free for at least 6 months since last chemo/radiotherapy, among those treated (with curative intent) with prior chemo/radiotherapy for limited-stage SCLC

Exclusion Criteria

• Active or untreated central nervous system (CNS) metastases as determined by computed tomography (CT) or magnetic resonance imaging (MRI) evaluation
• Malignancies other than SCLC within 5 years prior to randomization, with the exception of those with a negligible risk of metastasis or death treated with expected curative outcome
• Pregnant or lactating women
• History of autoimmune disease
• History of idiopathic pulmonary fibrosis, organizing pneumonia, drug-induced pneumonitis, idiopathic pneumonitis, or evidence of active pneumonitis on screening chest CT scan. History of radiation pneumonitis in the radiation field (fibrosis) is permitted.
• Positive test result for human immunodeficiency virus (HIV)
• Active hepatitis B or hepatitis C
• Severe infections at the time of randomization
• Significant cardiovascular disease
• Prior treatment with cluster of differentiation (CD) 137 agonists or immune checkpoint blockade therapies, anti-programmed death-1 (PD-1), and anti-PD-L1 therapeutic antibody
• History of severe (or known) hypersensitivity to chimeric or humanized antibodies or fusion proteins or any component of atezolizumab formulation.