Abstract 724: MPSA-AB5000: A high-throughput membrane proteins screening array for therapeutic biologics specificity profiling
Authors: Li dan , Xiong Junyi , Ning Jinying , Hao Feng 
Published: March 2024

Abstract
The development of novel antibody drugs is a lengthy journey. Many factors can lead to failures during clinical development. According to reports, off-target binding of antibodies could also be a significant cause. It has been stated that about 25% of preclinical candidates might have off-target issues. With the emergence of new modalities like CD3 bispecific antibodies, ADCs, and CAR-T therapies, early-stage off-target screening of antibodies has become even more crucial. Although techniques such as immunohistochemistry, ELISA, and flow cytometry (FACS) have been used for off-target testing of antibodies, these methods still lack sensitivity and specificity, and their throughput is limited. To address the need for antibody target deconvolution and receptor identification, we developed a novel membrane protein screening array-AB5000 (MPSA-AB5000). MPSA-AB5000 is a high-throughput cell-based platform for identifying the targets of antibodies and other ligands that bind to membrane proteins. MPSA-AB5000 is an excellent solution for antibody specificity screening, which enables early off-target screening and can de-risk the antibody drug development program. The MPSA-AB5000 makes use of the full coverage of unique human membrane proteins, including receptors, transporters, enzymes, miscellaneous, and others. Each membrane protein is expressed in live cells to ensure native conformation. In addition, the same membrane protein clones with a C-terminal epitope tag were constructed, allowing confirmation of protein expression and cellular location. To provide the highest level of sensitivity, MPSA-AB5000 uses luciferase reporter cell line detection. The wash-free strategy reduces false negatives, and signal amplification makes remarkable discrimination. Compared to similar technologies, we possess significant advantages in the following aspects: a. High sensitivity and sigh throughput: our technology platform offers not only high sensitivity, capable of detecting subtle interactions but also supports high-throughput screening, allowing for the evaluation of a large number of samples in a short timeframe. b. Avoidance of false negative signals: by eliminating washing steps, our method reduces the risk of false negative signals, ensuring reliable detection of non-specific binding. c. Comprehensive validation approaches: We employ various validation methods such as FACS and ELISA to eliminate false positive signals and enhance the accuracy and credibility of our results. All the advantages ensure that MPSA-AB5000 is more rapid, simple, and highly sensitive than traditional assays.
Citation Format: dan Li, Junyi Xiong, Jinying Ning, Feng Hao. MPSA-AB5000: A high-throughput membrane proteins screening array for therapeutic biologics specificity profiling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 724.