Abstract 482: Rapid highly multiplexed immunoprofiling of human fixed tissues by Orion imaging

Abstract

Abstract The dramatic impact of immune checkpoint inhibitors (ICIs) has focused interest in investigating immune-tumor cell interactions to understand mechanisms of ICI sensitivity and resistance, to identify patients that are responsive to specific treatments, and to develop new therapies. Multiplexed tissue imaging is a highly promising approach to immunoprofile tumors; it can assess many cell types and states within the context of preserved tumor architecture. However, the promise of highly multiplexed tissue imaging remains largely unfulfilled by current methods which are not compatible with pathology workflows. Here we present the development and implementation of Orion™ technology that permits whole-slide rapid single-pass imaging of up to 21 markers from formalin fixed paraffin embedded (FFPE) tissues. This method measures spectra for specific fluorophores to optimally sample the emitted light spectrum and distinguish multiple fluorescence excitation and emission channels across the spectral range of optical microscopes (~400-900 nm). To establish the utility of the Orion™ platform for immuno-phenotyping and immune checkpoint protein detection, we created an immunoprofiling panel of 21 qualified antibodies and labelled with fluorophores to subdivide the available emission spectrum in the 438-893 nm range. The panel includes markers that define subsets of T cells and macrophages. FFPE sections of human tonsil and matched primary and brain metastatic lung adenocarcinoma were stained and imaged in a single pass demonstrating staining patterns consistent with known micro-anatomic compartments and cell types in tonsil and identifying immune cell subtypes and heterogeneous checkpoint protein expression in tumor samples. An unexpected benefit of imaging with the Orion platform is the reduction of autofluorescence which is highly advantageous for the detection of proteins, like PD-L1, that function at very low levels. Orion imaging promises to accelerate discovery of predictive and prognostic biomarkers, enable pharmacodynamics study of immuno-oncology drugs undergoing clinical trials and ultimately provide clinically actionable diagnostic tests. Citation Format: Jia-Ren Lin, Daniel E. Campton, Jeremy Cooper, Yu-An Chen, Erin F. McCarty, Keith L. Ligon, Eric P. Kaldjian, Kyla Teplitz, Steve Reese, Sandro Santagata, Peter K. Sorger. Rapid highly multiplexed immunoprofiling of human fixed tissues by Orion imaging [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 482.