PO-044 Development of flow cytometric assays for CAR T cell manufacturing and patient immunomonitoring

Abstract

IntroductionAdoptive cell therapy using genetically engineered chimeric antigen receptor (CAR) T cells has demonstrated unprecedented potency in B cell malignancies, and offers new hope for curative responses in patients suffering from cancer. However, the manufacturing process for CAR T cells is very complex and has extensive demands on personnel and infrastructure, which is a major obstacle for their routine clinical use. To overcome these hurdles, the CliniMACS Prodigy allows generation of CAR T cells in a single automated and closed system.Material and methodsCliniMACS ProdigyMACSQuant AnalyzerMACS AntibodiesResults and discussionsFor assessment of CAR T cells during cell manufacturing and patient immunomonitoring we developed a set of different flow cytometric assays. These assays will be used for 1) in-process control, QC release testing, and concomitant research during the manufacturing process, and 2) for determination of CAR T cell persistance and phenotyping during patient immunomonitoring. Among others these assays allow to determine the general immune cell composition, CAR transduction efficiency, and further functional CAR T cell phenotypes like differentiation, activation, or exhaustion status.For identification of CAR T cells we developed CAR detection reagents that specifically bind to the antigen-recognition domain of the receptor. Thus, these detection reagents discriminate between various CAR constructs, and can be used for enumeration of CAR T cells during manufacturing and immunomonitoring.For all flow assays mentioned above so-called Express Modes have been programmed, that allow an automated acquisition and analysis of stained samples on MACSQuant Analyzers. These Express Modes feature predefined experiment settings and analysis templates, and apply a fully automated gating strategy that adapts for each individual data file. This allows for a high standardisation by reducing operator variability, full reproducibility of data analysis, and future integration into automated workflows.ConclusionElaborate flow assays specifically designed for CAR T cells, run with high-quality antibodies and fully automated flow analysis, provide a robust assessment of cell manufacturing and patient immunomonitoring. This will help with establishing complex individualised therapies and will allow us to understand from future clinical trials in greater detail the phenotypic changes occuring throughout the life time of a CAR T cell.