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.