Interview with Dr. J Keith Joung, MD, PhD at Keystone Symposia’s Precision Genome Engineering and Synthetic Biology: Designing Genomes and Pathways
Moving Genome Editing into the Clinic
My laboratory is focused on genome editing technologies and, more recently, on epigenome editing technologies as well. I got into this field first through protein engineering. So I was very interested in engineering zinc fingers, which then led to an interest in zinc finger nucleases, which, as you know, is a tool that can be used to do genome editing.
From there, we then progressed into the newer technologies, like Tal effector nucleases and, more recently, the CRISPR-Cas nucleases. So we continue to do improvements to the platform and make the tools broadly available to the research community.
The other aspect is that we’re very focused– I’m a physician scientist by training and my dream is to be able to utilize these for therapeutic applications. And so we’re also very focused on improving aspects of the technology that will help to translate them ultimately to the clinic and for the benefit of patients.
Treating Inherited Diseases with Genome Editing
I think I’m most excited about is the application of the technology for inherited diseases, treatment of inherited diseases. And so my lab is really focused on general and broad aspects of the technology that we think are important to develop in order to help ensure that these reagents can be used, not only for a broad range of diseases, but also very safely as they’re translated to the clinic and to the benefit of patients.
I think it’s very exciting that already, for research applications, the technology is being broadly used. So many, many people now are using zinc finger nucleases, TALENs, and obviously the CRISPR is very broadly. If one thinks about, though, translating these for therapeutic applications, where you’re going to either be modifying cells that would get introduced into a patient or even potentially modifying cells directly in the patient, then I think there are a couple of issues that really need to be focused on and addressed. And one of the major ones is that of specificity.
Getting into the Specifics of Specificity
So we know that we can make changes at a particular target sequence of interest. I think the question that has, to some degree, eluded the field is methods to be able to identify where else in the genome we may be causing unintentional or unwanted changes. And so, having those methodologies to be able to identify where those off target effects may be occurring is an important challenge. And my lab recently has begun to describe methods that will allow us to do that in a genome wide, unbiased, and in a highly sensitive way.
But clearly, additional work is needed to be able to define those platforms. And additionally, we and others have spent an enormous amount of time and effort just trying to improve the technology itself, to make the nucleases more specific for their targets. And, again, a lot of progress has been made, but I think that there’s additional work yet to be done on that front as well.
I think the challenge with specificity is that there are the need to be able to determine even effects that might occur with low frequency, especially if one thinks about therapeutic applications or approaches, where you’re modifying potentially very large numbers of cells, probably millions, if not up to hundreds of millions of these cells. Then even rare events, rare changes in DNA sequence or rare changes in, perhaps, the expression of certain genes, could have an impact that ultimately might be deleterious. And so understanding as completely as we can, and in as detailed a fashion as we can, where these alterations are occurring in the cell, I think, is really, really important going forward.
the challenge with specificity is that there are the need to be able to determine even effects that might occur with low frequency,
On the genome editing side, we’re starting to develop the tools to do that. We recently described a method called Guide seq which we believe is the first genome wide, unbiased way of looking at this and is fairly sensitive for detecting these types of off target alterations. And so tools like Guide seq and presumably things that will come along that are even more sensitive and perhaps even more comprehensive than that are going to be important to develop going forward.