Researchers published a new genome engineering method called “prime assembly” in Nature that enables targeted integration of long DNA fragments into precise genomic locations. The approach uses CRISPR-targeted dual flap synthesis to attach new DNA flaps that then capture matching DNA fragments for programmable replacement. The team reported that prime assembly can work in both dividing and non-dividing cells and was applied to targeted exon recoding, transgene integration and megabase-scale rearrangements in primary human cells. The authors position the method as potentially enabling more universal gene therapies by reducing the need for individually tailored short edits. Prime assembly is framed as reducing off-target and toxicity risks associated with untargeted insertion approaches and strategies that rely on double-strand breaks, since it is based on prime editing principles. For gene therapy developers, the announcement adds a new large-cargo integration tool that could address a key limitation of many current CRISPR platforms when therapeutic payloads exceed delivery and editing constraints.