Testing the Addition of a New Immunotherapy Drug, Atezolizumab (MPDL3280A), to the Usual Chemoradiation (CRT) Therapy Treatment for Limited Stage Small Cell Lung Cancer (LS-SCLC)

PRIMARY OBJECTIVE: I. To compare overall survival (OS) for patients with LS-SCLC treated with chemoradiation +/- atezolizumab. SECONDARY OBJECTIVES: I. To compare progression free survival (PFS) for patients with limited stage small cell lung cancer (LS-SCLC) treated with chemoradiation +/- atezolizumab. II. To determine overall response rate (ORR), rates of local control, and distant metastases free survival with chemoradiation +/- atezolizumab. III. To characterize immune mediated and non-immune mediated toxicity from chemoradiotherapy plus atezolizumab. IV. To compare quality of life, as measured by the Functional Assessment of Cancer Therapy-Trial Outcome Index (FACT-TOI), for patients undergoing chemoradiation +/- atezolizumab. V. To evaluate the quality-adjusted survival, using scores from the 5-level EuroQol 5-dimensional questionnaire (EQ-5D-5L), of chemoradiation +/- atezolizumab for patients with LS-SCLC. VI. To characterize fatigue, as measured by the Patient-Reported Outcomes Measurement Information System (PROMIS), following chemoradiation +/- atezolizumab. VII. To determine the association of small cell lung cancer (SCLC) molecular subtypes with clinical outcomes. EXPLORATORY OBJECTIVES: I. To collect biospecimens at baseline, day 1 and 3 months after the end of chemoradiotherapy, to allow for future analyses. II. To characterize patient-reported symptomatic toxicities measured by the Patient-Reported Outcomes - Common Terminology Criteria for Adverse Events (PRO-CTCAE). III. To characterize the concordance between tumor and circulating cell-free deoxyribonucleic acid (cfDNA)-determined molecular subtypes. OUTLINE: Patients are randomized to 1 of 2 arms. ARM I: Patients receive etoposide intravenously (IV) on days 1-3 and cisplatin IV or carboplatin IV on day 1. Cycles repeat every 21 days for 3 cycles in the absence of disease progression or unacceptable toxicity. Patients also undergo three-dimensional conformal radiation therapy (3D-CRT) or intensity-modulated radiation therapy (IMRT) twice daily (BID) for approximately 3 weeks or once daily (QD) for approximately 6-7 weeks in the absence of disease progression or unacceptable toxicity. Patients undergo blood specimen collection throughout the trial. ARM II: Patients receive treatment as in Arm I. Patients also receive atezolizumab IV over 30-60 minutes on day 1 or 2 of each chemotherapy cycle. Cycles repeat every 3 weeks for 17 cycles (1 year) in the absence of disease progression or unacceptable toxicity. Patients undergo blood specimen collection throughout the trial. After completion of study treatment, patients are followed up every 3 months for 2 years, then every 6 months for 3 years, then annually thereafter.