Abstract LB180: SPOC, A highly multiplexed platform to study the kinetics of hundreds of biomolecular interactions: applications for early cancer detection
Authors: Cook Rebecca , Agu Chidozie Victor , Martelly William , Bell Peter A. , Mohan Mukilan , Takulapalli Bharath 
Published: April 2023

Abstract
Tissue specific tumor neo-antigens and tumor associated antigens (TAAs) play a pivotal role in immune system interaction with cancer cells. Mutated, alternately spliced, over-expressed, mis-folded and abnormally post-translationally modified proteins may elicit immune responses that suppress tumor development. As these cancer specific proteins are distinct from normal self-proteins they offer the possibility of serving as highly-specific cancer biomarkers for early detection. TAAs are increasingly being targeted for priming the immune response to immunotherapies and cancer vaccines. Consequently, there has been an exponential increase in research on neo-antigen profiling using sequencing and multi-omic technologies. However, proteomic tools capable of studying and profiling the cancer proteome are limited. To contribute to this, we are developing a novel proteomic screening platform termed Sensor-integrated Proteome on Chip (SPOC) that enables high-throughput (HTP) screening of cancer proteins for loss or gain of function analysis, and humoral immune response profiling. SPOC platform enables use of surface plasmon resonance (SPR) biosensing for kinetic interaction profiling of 100s to 1000s of proteins at once, which can be applied to discovery and characterization of autoantibodies and neoantigens. SPOC uses human cell-free in vitro transcription and translation to express fusion capture-tagged proteins of interest from DNA plasmids printed in nanowells etched into a silicon slide. As proteins are expressed, they are captured covalently onto an overlaid gold-coated surface in individual spots via the capture ligand. The capture ligand requires the tag to be properly folded for binding, thus proteins on the surface are presumed to be fully folded when captured. When SPOC chips are analyzed using SPR, kinetic measurements of protein interactions can be obtained for each protein spot over time (RMax, Kon, Koff, etc.). SPOC arrays may be probed with a variety of biological molecules including small molecule drugs, antibodies, and other proteins. Data can be analyzed using bioinformatics and machine learning for neo-antigen discovery and to generate distinct signatures of disease. To demonstrate SPOC utility for neo-antigen discovery and characterization, a serum sample with known anti-p53 autoantibodies was analyzed on a SPOC SPR chip containing expressed p53 protein spots distributed throughout the array. Increases in SPR signals were observed for each p53 spot on the array as anticipated.
Citation Format: Rebecca Cook, Chidozie Victor Agu, William Martelly, Peter A. Bell, Mukilan Mohan, Bharath Takulapalli. SPOC, A highly multiplexed platform to study the kinetics of hundreds of biomolecular interactions: applications for early cancer detection [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB180.