# Engineered Transformer Base Editor with Enhanced Editing Efficiency

Article · Chen B, Liang L, Xu R, Wang T, Chen H, Lu D

- Archive id: doi:10.1002/advs.77657
- Published: 2026-09-10
- Venue: Advanced science (Weinheim, Baden-Wurttemberg, Germany)
- DOI: https://doi.org/10.1002/advs.77657
- PMID: 42723179
- PMCID: PMC13562778
- Citations: 0
- Source URL: https://doi.org/10.1002/advs.77657
- PDF: https://europepmc.org/articles/PMC13562778/pdf
- Provenance: europepmc

## Abstract

Canonical cytosine base editors (CBEs) achieve precise C-to-T conversions without inducing DNA double-strand breaks (DSBs), yet their clinical potential remains hampered by substantial off-target (OT) mutations. The recently developed transformer base editor (tBE) significantly reduces both genomic and transcriptomic OT mutations by using a cleavable deoxycytidine deaminase inhibitor (dCDI) domain. However, the modest base editing efficiency limits its broader applications. Here, through rational deaminase engineering and fusion of a uracil DNA glycosylase inhibitor (UGI) domain, we developed the engineered tBE (etBE). The etBE exhibited substantially enhanced editing efficiencies compared with the parental tBE (up to 35.11-fold improvement), while maintaining high editing fidelity and background levels of OT mutations. As a therapeutic proof-of-concept, dual adeno-associated virus (AAV)-mediated delivery of etBE targeting proprotein convertase subtilisin/kexin type 9 (PCSK9), a well-established therapeutic target for cardiovascular diseases, was evaluated in a humanized mouse model. The treatment achieved efficient in vivo base editing (up to 35.13%), resulting in substantial reductions in plasma PCSK9 protein (24%) and low-density lipoprotein cholesterol (LDL-C) levels (33%), while inducing only minimal OT mutations. Collectively, etBE represents a highly efficient and specific base editing platform with enormous potential for both basic research and clinical applications.

_Abstract reproduced under CC-BY (article license as recorded by Europe PMC; abstract reproduced unmodified apart from markup removal)._

Topics: [CRISPR & Gene-Editing Therapies](https://space-kitty.com/topics/gene-editing-therapies)

---
Space Kitty Archive · https://space-kitty.com · API: https://space-kitty.com/api/v1 · MCP: https://space-kitty.com/mcp · Premium: $0.20/request via x402 (Base Sepolia (testnet)). Metadata: arXiv (CC0), OpenAlex (CC0), Europe PMC (CC BY/CC0 works), ClinicalTrials.gov.