Prime editing (PE) is a precise genome-editing technology that avoids double-strand breaks, holding great promise for clinical and agricultural applications. However, its genome-wide off-target effects are not fully understood, raising safety concerns. Here, we systematically compared the safety profiles of four prime editor variants (PE2max, PE3max, PE4max, and PE5max) using PEM-seq and RNA-seq. We further applied an ultra-sensitive method, Genome-wide Off-target analysis by Two-cell embryo Injection (GOTI), to assess PE5max. Our results show that PE5max did not produce detectable sgRNA-dependent off-target single-nucleotide variants (SNVs) in the GOTI assay and induced only limited large deletions and chromosomal translocations. Collectively, this side-by-side benchmarking under matched conditions demonstrates that PE5max achieves an improved specificity profile, with no detectable increase in genome-wide off-target SNVs, advancing its potential for safer therapeutic use.
Zheng et al. (Sat,) studied this question.