Simultaneous orthogonal cell engineering by a single CRISPR-Cas9 polyfunctional editor

The parallel disruption of multiple genes coupled with targeted transgene insertion offers a powerful strategy for more effective and precise cell engineering. However, such orthogonal editing involves the induction of multiple DNA breaks, raising safety concerns related to the risks of chromosomal translocations. Here, we present a polyfunctional CRISPR-Cas9-based strategy that enables both transgene insertion and epigenetic silencing at distinct genomic loci in a single treatment without inducing reciprocal chromosomal translocations. This is accomplished through an optimized all-in-one epigenome editor equipped with a catalytically active Cas9, whose endonuclease activity is selectively disabled at epigenetically silenced loci using truncated gRNAs. As a proof of concept, we demonstrate that this platform enables efficient multi-locus editing, including functional replacement of the endogenous TCR with a tumor-selective one, targeted insertion of a prototypic CAR with either a selectable marker or an immunomodulatory receptor into a TCR locus or a ubiquitously expressed gene, and durable, multiplexed epigenetic silencing of clinically relevant genes in primary human T cells. Polyfunctional editing establishes a versatile and safe framework for orthogonal editing, broadening the scope of genome and epigenome engineering in cancer immunotherapy and beyond. Cell engineering through multiple genetic edits holds therapeutic potential but raises safety concerns. Here, authors develop a CRISPR-Cas9 molecule enabling simultaneous transgene insertion and multi-gene epigenetic silencing, proving efficacy and safety in human T cells for cancer immunotherapy.