Tremelimumab and Durvalumab With or Without Radiation Therapy in Patients With Relapsed Small Cell Lung Cancer

PRIMARY OBJECTIVE: I. To assess the efficacy (progression free survival \[PFS\] and objective response rate \[ORR\]) of combined immune checkpoint inhibitor therapy as treatment for relapsed small-cell lung cancer (SCLC). SECONDARY OBJECTIVES: I. To assess the impact of antigen priming using radiation therapy (XRT) on the efficacy of immune checkpoint inhibitors. II. To determine immune related objective response rate. III. To estimate overall survival measured as time from randomization to death from any cause. TERTIARY OBJECTIVES: I. To characterize tumor infiltrating lymphocytes (TILs) and programmed cell death 1 ligand 1 (PD-L1)/programmed cell death 1 (PD1) expression in paired tumor biopsies at baseline, end of cycle 2 and at the time of progression. II. To determine dynamic changes in cell free deoxyribonucleic acid (DNA) (cfDNA) and the immunophenotype of peripheral blood repertoire of circulating lymphocytes using multiparameter flow cytometry. III. To determine changes in circulating cytokine mediators of inflammation and immunity using Luminex assay. OUTLINE: Patients are randomized to 1 of 2 treatment arms. ARM I: Patients receive tremelimumab intravenously (IV) over 1 hour on day 1. Treatment repeats every 4 weeks for up to 4 courses in the absence of disease progression or unacceptable toxicity. Patients also receive durvalumab IV over 1 hour on day 1. Treatment repeats every 4 weeks for up to 1 year in the absence of disease progression or unacceptable toxicity. Patients achieving disease control may restart treatment upon evidence of progressive disease, with or without confirmation. ARM II: Patients undergo radiation therapy daily for 5 days over 1 week or for 3 fractions every other day for 1 week and then receive the same treatment as in Arm I. After completion of study treatment, patients are followed up periodically.