University of Kansas Medical Center

Pre-Operative Immuno-Modulatory SBRT (POIMS Trial): A Pilot Trial in Early Stage NSCLC

Purpose

The current proposal is structured as a pilot trial to evaluate the impact of non-ablative SBRT (800 cGy X 3 fractions) as an immunomodulatory mechanism in patients with early stage NSCLC who are surgical candidates. Tumor, normal tissue and blood specimens will be analyzed for immunomodulatory changes including phenotypic changes in tumor cell surface marker expression, tumor and normal tissue microenvironment and gene expression profiles, serum/blood immune profile changes, and circulating tumor cell immunophenotypic and gene expression alterations. Published literature showed that cytotoxic doses of XRT may not elicit a clinically meaningful alteration in the immune profile. Further, studies using an animal model have concluded a fractionated regimen induces a greater abscopal effect than single dose radiation. Furthermore, research has shown a regimen of 800 cGy X 3 fractions yielded the most significant changes in the immune profile compared to 2000 cGy X 1 or 600 cGy X 5. The immune response within the tumor milieu is a complex dynamic process with an interplay among lymphocyte subsets, antigen presenting cells/dendritic cells, macrophages, and tumor cells. The interactions between the various components is orchestrated by a variety of extracellular and intracellular signaling pathways involving ligand and cell surface expression, cytokine release, and activation or inhibition of a variety of T cell subsets. In order to comprehensively define the immunomodulatory effect of three fractions of 800 cGy on the primary tumor, the investigators will analyze the following: tumor cell surface phenotype, tumor microenvironment immune profile and gene expression profile, T cell repertoire changes in tumor tissue and peripheral blood, and circulating tumor cell phenotype and gene expression profiles. Each of these components has been shown to be impacted by radiation in either a cell culture or animal model systems. By characterizing, quantitating and defining these changes related to three fractions of 800 cGy, it will directly provide important insights to inform rational uses of XRT and immunotherapy in the future.