Multiplex Base Editing to Protect from CD33-Directed Therapy: Implications for Immune and Gene Therapy

On-target toxicity to normal cells is a major safety concern with targeted immune and gene therapies. Here, we developed a base editing (BE) approach exploiting a naturally occurring CD33 single nucleotide polymorphism leading to removal of full-length CD33 surface expression on edited cells. CD33 editing in human and nonhuman primate (NHP) hematopoietic stem and progenitor cells (HSPCs) protects from CD33-targeted therapeutics without affecting normal hematopoiesis in vivo , thus demonstrating potential for novel immunotherapies with reduced off-leukemia toxicity. For broader applications to gene therapies, we demonstrated highly efficient (>70%) multiplexed adenine base editing of the CD33 and gamma globin genes, resulting in long-term persistence of dual gene-edited cells with HbF reactivation in NHPs. In vitro , dual gene-edited cells could be enriched via treatment with the CD33 antibody-drug conjugate, gemtuzumab ozogamicin (GO). Together, our results highlight the potential of adenine base editors for improved immune and gene therapies. ![Figure][1] ### Competing Interest Statement This study was funded by a grant from Vor Biopharma and 1R21CA256461 at Columbia University and by a grant from NIH/NHLBI R01 HL136135_2 at the Fred Hutchinson Cancer Center. Columbia University has licensed technology that is the subject of this study to Vor Biopharma. F.B., A.M.A., and S.M. are coinventors on issued and pending patent applications licensed to Vor Biopharma. S.M. has equity ownership and is on the Scientific Advisory Board of Vor Biopharma. HPK is or was a consultant to and has or had ownership interests with Rocket Pharmaceuticals, Homology Medicines, Vor Biopharma and Ensoma Inc. HPK has also been a consultant to CSL Behring and Magenta Therapeutics. D.R.L. is a consultant for Prime Medicine, Beam Therapeutics, Pairwise Plants, and Chroma Medicine, and Nvelop Therapeutics, companies that use or deliver genome editing or genome engineering agents, and owns equity in these companies. [1]: pending:yes