%0 Journal Article %A Woodruff, Rosie %A Parekh, Farhaan %A Lamb, Katarina %A Mekkaoui, Leila %A Allen, Christopher %A Smetanova, Katerina %A Huang, Jasmine %A Williams, Alex %A Toledo, Gerardo Santiago %A Lilova, Koki %A Roddie, Claire %A Sillibourne, James %A Pule, Martin %D 2023 %F discovery:10180184 %I Elsevier BV %J Molecular Therapy: Methods & Clinical Development %K base editing, BE4max, chimeric antigen receptor, circular RNAPD-1TIM3 %T Large-scale manufacturing of base-edited chimeric antigen receptor T cells %U https://discovery.ucl.ac.uk/id/eprint/10180184/ %V 31 %X Base editing is a revolutionary gene-editing technique enabling the introduction of point mutations into the genome without generating detrimental DNA double-stranded breaks. Base-editing enzymes are commonly delivered in the form of modified linear messenger RNA (mRNA) that is costly to produce. Here, we address this problem by developing a simple protocol for manufacturing base-edited cells using circular RNA (circRNA), which is less expensive to synthesize. Compared with linear mRNA, higher editing efficiencies were achieved with circRNA, enabling an 8-fold reduction in the amount of RNA required. We used this protocol to manufacture a clinical dose (1 × 108 cells) of base-edited chimeric antigen receptor (CAR) T cells lacking expression of the inhibitory receptor, PD-1. Editing efficiencies of up to 86% were obtained using 0.25 μg circRNA/1 × 106 cells. Increased editing efficiencies with circRNA were attributed to more efficient translation. These results suggest that circRNA, which is less expensive to produce than linear mRNA, is a viable option for reducing the cost of manufacturing base-edited cells at scale. %Z © 2023 The Authors. Published by Elsevier under a Creative Commons license (http://creativecommons.org/licenses/by-nc-nd/4.0/).