David R. Liu, PhD
Richard Merkin Professor and Director of the Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of MIT and Harvard, Thomas Dudley Cabot Professor of the Natural Sciences at Harvard University, and Investigator of the Howard Hughes Medical Institute
Base Editing and Prime Editing: Precise Gene Correction Without Double-Strand DNA Breaks
In this lecture I describe the development and therapeutic application of two precision gene editing technologies that install or correct targeted mutations without requiring double-strand DNA breaks, thereby minimizing undesired consequences of chromosomal cleavage such as translocations, p53 activation, chromothripsis, and uncontrolled mixtures of indels. We developed base editors, proteins that directly perform chemistry on individual DNA bases in living cells to install or correct mutations at targeted positions in genomic DNA. We recently engineered CRISPR-free, all-protein base editors that enabled the first purposeful changes in the sequence of mitochondrial DNA in living cells. By integrating base editors with ex vivo and in vivo delivery strategies that deliver therapeutic proteins, we rescued animal models of human genetic diseases including sickle-cell disease and progeria. Clinical trials to treat genetic diseases with base editing are already underway, with additional clinical trials scheduled to begin this year. I will also describe prime editors, engineered proteins that directly write new genetic information into a specified DNA site without requiring double-strand DNA breaks or donor DNA templates. Prime editing can mediate any base substitutions, small insertions, and/or small deletions in living cells in vitro and in vivo, and has been applied to directly correct pathogenic alleles that previously could not be corrected in therapeutically relevant cells. We recently illuminated the cellular determinants of prime editing outcomes, and used the resulting insights to develop next-generation prime editing systems with substantially higher editing efficiencies and product purities. The combination of prime editing and recombinases enable targeted gene-sized integration and inversion at loci of our choosing in human cells. Our recent development of engineered virus-like particles (eVLPs) provide additional in vivo delivery methods for gene editing proteins that minimize off-target editing and the risk of oncogenic DNA integration. Base editing and prime editing enable precise target gene correction, rather than target gene disruption, under therapeutically relevant conditions in a wide range of organisms with broad implications for the life sciences and therapeutics.
