A PHASE III, RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED STUDY OF ATEZOLIZUMAB PLUS CARBOPLATIN AND ETOPOSIDE WITH OR WITHOUT TIRAGOLUMAB (ANTI-TIGIT ANTIBODY) IN PATIENTS WITH UNTREATED EXTENSIVE-STAGE SMALL CELL LUNG CANCER

This study will evaluate the efficacy of tiragolumab plus atezolizumab and carboplatin and
etoposide (CE) compared with placebo plus atezolizumab and CE in participants with
chemotherapy-naive extensive-stage small cell lung cancer (ES-SCLC). Eligible participants
will be stratified by Eastern Cooperative Oncology Group (ECOG) Performance Status (0 vs. 1),
LDH ( ULN), and presence or history of brain metastasis
(yes vs. no) and randomly assigned in a 1:1 ratio to receive one of the following treatment
regimens during induction phase:

- Arm A: Tiragolumab plus atezolizumab plus CE

- Arm B: Placebo plus atezolizumab plus CE

Following the induction phase, participants will continue maintenance therapy with either
atezolizumab plus tiragolumab (Arm A) or atezolizumab plus placebo (Arm B).

Inclusion Criteria:

- Histologically or cytologically confirmed extensive-stage small cell lung cancer
(ES-SCLC)

- No prior systemic treatment for ES-SCLC

- Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1

- Measurable disease, as defined by Response Evaluation Criteria in Solid Tumors version
1.1 (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:

- Symptomatic or actively progressing central nervous system (CNS) metastases

- Malignancies other than small cell lung cancer (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

- 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 on screening
chest computed tomography (CT) scan

- Positive test result for human immunodeficiency virus (HIV)

- Active hepatitis B or hepatitis C

- Severe infection at the time of randomization

- Treatment with any other investigational agent within 28 days prior to initiation of
study treatment

- Prior treatment with CD137 agonists or immune checkpoint blockade therapies,
anti-cytotoxic T lymphocyte-associated protein 4 (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 randomization