Utilization of novel highly multiplexed immunofluorescence microscopy technology to understand immunological tumor microenvironments in small cell lung carcinoma patients receiving combination PD-L1 and PARP inhibition therapy.

Abstract

e14289 Background: Immune checkpoint inhibitors have changed the way we treat most malignant tumors especially lung carcinomas. While PD-L1 is the only FDA approved companion diagnostic used to predict response, its accuracy and specificity is lacking. Thus, new biomarkers and mechanisms of checkpoint inhibitor need to be elucidated. A major limitation with the current approved method, immunohistochemistry, is that it can typically only measure one parameter per tissue section. Currently new multiplexing microscopy techniques are being developed that allow us to see multiple parameters at the cell level, which can answer new questions regarding tumor immune microenvironments (TIME). In this study we used a novel multiplexed immunofluorescent (MxIF) microscopy technique, Cell DIVE™ (GE Healthcare, Issaquah, WA), to analyze formalin fixed paraffin embedded (FFPE) tissue samples from small cell lung carcinoma (SCLC) patients treated with a PD-L1 inhibitor, durvalumab (MEDI4736), in combination with a PARP inhibitor, olaparib. Methods: Biopsies from patients enrolled in a phase II expansion cohort clinical trial (NCT02484404) treated with durvalumab and olaparib were analyzed. Tumor immune response from a cohort of 3 responders and 3 non-responders, before and after treatment, underwent MxIF analysis using biomarkers including CD3, CD4, CD8, CD20, CD39, CD45RA, CD45RO, CD56, CD57, CD103, FOXP3, GATA3, LAMP1, PD-L1 and T-bet. Our panel was able to effectively discern T-cells (including subsets, maturation, and function), B-cells, and NK cells and their interaction with tumor cells. The results were validated for accuracy and consistency using immunohistochemistry and Vectra Polaris Imaging System. Results: Spatial analysis of TIME showed responders (3/3) were associated with an inflamed CD8+ T-cell tumor microenvironment while non-responders (3/3) displayed an excluded or desert CD8+ T-cell tumor microenvironment. MxIF/Cell DIVE™ allowed us to further characterize the immune response. Conclusions: Analyzing the type and pattern of immune response using multiplexed immunofluorescent and single cell characterization microscopy may better predict prognosis than PD-L1 immunohistochemistry in SCLC patients treated with immune checkpoint inhibitors. Clinical trial information: NCT02484404.