Gag-derived VLPs and the delivery of CRISPR-Cas9 system in Gene and Cell Therapies

Abstract

Cancer had been an unsolved problem for decades that accounts for 375,400 cases in UK each year, with only a 50% survival rate of 10 or more years. With more recent advances in gene editing techniques like CRISPR-Cas9, immunotherapy was able to advance to better engineer T cells for adoptive T cell transfer therapies such as T cell receptor (TCR) therapy and chimeric antigen receptor T cell (CAR-T) therapy. For more efficient delivery of CRISPR-Cas9 system, several human immunodeficiency virus type 1 (HIV-1) as well as murine leukaemia virus (MLV) group-specific antigen (Gag)-based virus like particles (VLP)s were designed by either directly fusing the Cas9 mRNA, Cas9 protein, or sgRNA to either the N- or C-terminus of the Gag polyprotein or by inserting or replacing a part of the Gag polyprotein. The Gag polyproteins can then self-assemble, carrying their cargo and packaging them inside the VLP. All designs demonstrated a significant increase in cargo capacity and successful delivery of both Cas9 mRNA and Cas9 proteins or nucleases for T cell engineering, and this provides great potential for additional gene modifications in order to target specifically solid tumour due to their high efficiency and multiplexed editing nature.