Large-scale manufacturing of base-edited chimeric antigen receptor T cells.

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 × 10 ⁸ 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 × 10 ⁶ 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.
Competing Interests: R.W., F.P., K.L., L.M., C.A., A.W., G.S.T, K.L., J.S., and M.P. are employees of Autolus Therapeutics plc and hold equity shares or options in the company. M.P. receives royalty share from patents licensed to Autolus Therapeutics plc.
(© 2023 The Authors.)