Researchers co-led by Ludwig Stanford’s Crystal Mackall reported in a February publication in Cell their development of a potentially safer, more versatile CRISPR editing platform named MEGA (for Multiplexed Effector Guide Arrays) and demonstrated in preclinical studies that it holds the potential to dramatically improve the efficacy of CAR-T cell immunotherapies. The platform employs CRISPR-Cas13d—which targets RNA, not DNA—to edit multiple transcripts of genes at once while nixing the ever-present risk associated with erroneous, or “off-target”, edits made to genomic DNA, which can themselves theoretically seed cancer. The researchers employed MEGA in a screen in which they knocked down 6,400 paired combinations of genes in cultured T cells to find novel paired genes that could be targeted to improve CAR-T cell function. They also engineered the RNA-editing system to sport an on/off switch, linking its programmable execution of multiplexed CAR-T cell engineering to the presence of an FDA-approved antibiotic. Finally, Crystal and her colleagues demonstrated how MEGA could be used to improve the metabolic fitness of CAR-T cells, showing that their engineering of the cells altered the way in which they generate energy, switching from glycolysis to oxidative phosphorylation, which greatly improved their persistence within tumors. This boosted their proliferative capacity by an order of magnitude and improved tumor suppression to a similar degree in a mouse model of cancer.
A versatile CRISPR-Cas13d platform for multiplexed transcriptomic regulation and metabolic engineering in primary human T cells
Cell, 2024 February 21