Folate receptor-mediated delivery of Cas9 RNP for enhanced immune checkpoint disruption in cancer cells

The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associatedprotein9(Cas9)system offers great opportunities for the treatment of numerous diseases by precise modification of the genome. The functional unit of the system is represented by Cas9/sgRNA ribonucleoproteins (RNP), which mediate sequence-specific cleavage of DNA. For therapeutic applications, efficient and cell-specific transport into target cells is essential. Here, Cas9 RNP nanocarriers are described, which are based on lipid-modified oligoamino amides and folic acid (FolA)-PEG to realize receptor-mediated uptake and gene editing in cancer cells. In vitro studies confirm strongly enhanced potency of receptor-mediated delivery, and the nanocarriers enable efficient knockout of GFP and two immune checkpoint genes, PD-L1 and PVR, at low nanomolar concentrations. Compared with non-targeted nanoparticles, FolA-modified nanocarriers achieve substantially higher gene editing including dual PD-L1/PVR gene disruption after injection into CT26 tumors in vivo. In the syngeneic mouse model, dual disruption of PD-L1 and PVR leads to CD8+ T cell recruitment and distinct CT26 tumor growth inhibition, clearly superior to the individual knockouts alone. The reported Cas9 RNP nanocarriers represent a versatile platform for potent and receptor-specific gene editing. In addition, the study demonstrates a promising strategy for cancer immunotherapy by permanent and combined immune checkpoint disruption.