PRIMARY OBJECTIVE:

I. To compare overall survival (OS) in patients with inoperable, early stage non-small cell lung cancer (NSCLC) randomized to stereotactic body radiation therapy (SBRT) with or without atezolizumab.

SECONDARY OBJECTIVES:

I. To compare investigator-assessed progression-free survival (IA-PFS) between the arms.

II. To compare progression free survival (PFS) by blinded independent centralized review (BIRC) between the arms in a random subset of patients.

III. To evaluate distant, locoregional, and local failure rates within each treatment arm.

IV. To evaluate the frequency and severity of toxicities within each treatment arm.

ADDITIONAL OBJECTIVE:

I. To collect specimens for banking.

OUTLINE: Patients are randomized to 1 of 2 arms.

ARM A: Patients receive atezolizumab intravenously (IV) over 30-60 minutes on day 1. Treatment repeats every 21 days for 8 cycles. Starting on day 1 cycle 3, patients also undergo SBRT for 3-5 treatments over 1-3 weeks.

ARM B: Beginning 21 days after randomization, patients undergo SBRT for 3-5 treatments over 1-3 weeks.

After completion of study treatment, patients are followed up at weeks 18, 30, 42, and 54, every 6 months for 2 years, and then every 12 months for 2 years.