Though AsCas12a fills a crucial gap in the current genome editing toolbox, it exhibits relatively poor editing efficiency, restricting its overall utility. In collaboration with Integrated DNA Technologies, we showed that this engineered variant we refer to as AsCas12a Ultra, increased editing efficiency to nearly 100% at all sites examined in HSPCs, iPSCs, T cells, and NK cells. We showed that AsCas12a Ultra maintains high on-target specificity thereby mitigating the risk for off-target editing and making it ideal for complex therapeutic genome editing applications. We achieved simultaneous targeting of three clinically relevant genes in T cells at >90% efficiency and demonstrated transgene knock-in efficiencies of up to 60%. We demonstrate site-specific knock-in of a CAR in NK cells, which afforded enhanced anti-tumor NK cell recognition, potentially enabling the next generation of allogeneic cell-based therapies in oncology. AsCas12a Ultra is an advanced CRISPR nuclease with significant advantages in basic research and in the production of gene edited cell medicines.

Learning Objectives:

1. Identify the engineered AsCas12a Ultra nuclease is commercially available to researchers from Integrated DNA Technologies

2. Recall this engineered AsCas12a nuclease forms the basis for EDIT-301, an experimental treatment for sickle cell disease which is currently being tested in the clinic

3. Recall this engineered AsCas12a nuclease breaks the observed paradigm where most natural and engineered CRISPR nuclease variants that achieve very high specificity come with a cost to on-target editing activity in most clinically relevant cell types