Primary objective is to measure the change in the levels of circulating tumor DNA (ctDNA) in Cohort 1 (MRD+) due to the addition of platinum doublet chemotherapy in subjects with stage III unresectable disease with positive DNA treated with consolidation chemotherapy and immunotherapy.~Secondary Objectives:~To determine the proportion of subjects in Cohort 1 MRD+ for whom ctDNA becomes undetectable after chemotherapy~To describe overall survival (OS) of subjects with baseline detectable ctDNA (Cohort 1 MRD+) vs baseline undetectable ctDNA (Cohort 2 MRD ) ·To describe progression free survival (PFS) between subjects with baseline detectable (Cohort 1 MRD+) vs baseline undetectable ctDNA (Cohort 2 MRD ) ·To describe the frequency and severity of toxicity of consolidation durvalumab plus chemotherapy
The purpose of this study is to test whether or not number of circulating cancer cells detected in the blood can be decreased the by combining the standard treatment (durvalumab) with additional chemotherapy