Comparison of CAR-T cell-mediated cytotoxicity assays with suspension tumor cells using high-throughput plate-based image cytometry method

Abstract

Abstract In the recent decade, chimeric antigen receptor (CAR)-T cell therapy has revolutionized strategies for cancer treatments due to its highly effective clinical efficacy and response for B cell malignancies. Currently, there are six CAR-T cell products available in the market including Kymriah, Yescarta, Tecartus, Breyanzi, Abecma, and Carvykt. The success of CAR-T cell therapy has stimulated the increase in the research and development of various CAR constructs to target different tumor types. Therefore, a robust and efficient in vitro potency assay is needed to quickly identify potential CAR gene design from a library of construct candidates. Traditionally, in vitro CAR-T cell-mediated cytotoxicity is assessed using release assays such as 51Cr (radioactivity), calcein (fluorescence), and LDH (enzymatic). Image cytometry methodologies have been utilized for various CAR-T cell-mediated cytotoxicity assay using different fluorescent labeling methods, mainly due to their ease-of-use, ability to capture cell images for verification, and higher throughput performance. In this work, we employed the Celigo high-throughput plate-based Image Cytometer to evaluate and compare two CAR-T cell-mediated cytotoxicity assays using GFP-expressing or fluorescent dye-labeled myeloma and plasmacytoma cells. Performing time- and E:T ratio-dependent CAR-T cell-mediated cytotoxicity assays, the GFP-based method demonstrated higher sensitivity in detecting the level of cytotoxicity when compared to the CMFDA/DAPI viability method. We have established the criteria and considerations for the selection of cytotoxicity assays that are fit-for-purpose to ensure the results produced are meaningful for the specific testing conditions. None