Quadruple pegRNA enables programmable and efficient large genomic insertion

Precise, site-specific insertion of large gene sequences holds great promise for the treatment of diverse genetic disorders. Although prime editing using paired guide RNAs (pegRNAs) can mediate targeted integration, insertion efficiency drops sharply for payloads exceeding 300 base pairs1-3. Here we present a rationally designed quadruple pegRNA strategy (QuadPE) for efficient and programmable insertion of large DNA fragments. Through screening different designs, we identified that combinations of two genome-targeting pegRNAs in a PAM-out or PAM-in orientation, when paired with two donor-targeting pegRNAs in linear or circular form, yield optimal efficiency. Using QuadPE, we achieved stable integration efficiency of DNA fragments ranging from 1.6 to 26 kb, with efficiencies of around 40% at multiple loci with minimal off-target insertion activity. QuadPE substantially outperformed recombinase-mediated (PASSIGE and PASTE)4,5 and transposase-mediated (CAST)6 insertion systems, particularly for larger payloads, showing a 11-fold, 61-fold and 12-fold improvement for a 9.5 kb insertion, respectively. Notably, QuadPE was effective in both dividing and non-dividing primary cells such as human primary T cells and post-mitotic neurons, establishing QuadPE as a powerful and precise platform for large-fragment gene insertion without the need for double-stranded breaks or recombinases.