Will Gene Editing Be in Your Medical Future?

Leigh Page

Disclosures

January 05, 2016

In This Article

Great Potential, but Not Ready for Prime Time

Gene editing is a very compelling concept for physicians. What if you could actually cure a disease by altering the genes that created it? Then your patients wouldn't need drugs and other therapies, which often involve high costs and dangerous side effects. This revolutionary approach could either remove the disease or reduce it to a nonthreatening level.

Slowly but surely, researchers are trying to bring the concept of gene editing closer to clinical reality. Still, no one is saying that this therapy would be commercially available any time soon. Use of gene editing on humans is just beginning to enter clinical trials. At this point, research is focusing only on a small number of diseases that affect relatively small populations.

In gene editing, "the idea is not to treat the disease but to physically change the DNA in a way that cures the disease," says Fyodor Urnov, PhD, a genetic biologist and senior scientist at Sangamo BioSciences, a California company that owns the rights to a form of gene-editing technology called "zinc-finger nucleases."

More than 3000 diseases have been linked to mutations in individual genes, but researchers are starting with diseases that are most likely to yield positive results. These include HIV and diseases that involve a defect in only one gene, such as hemophilia, sickle cell disease, and beta thalassemia. Meanwhile, "there are many diseases that we are not looking at, such as heart disease, because they have contributions from multiple genes," Dr Urnov says.

How Gene Editing Works

Gene editing—more properly called "genome editing"—involves removing and adding specific bits of DNA in a patient's genome. The process is a lot like cutting and pasting words, which is why the process is called "editing." Sangamo's zinc-finger nucleases are engineered from natural enzymes and introduced into the blood, or into the brain or other organs. They can also be used outside the body on stem cells or T cells, which are then introduced into the body.

The zinc finger is able to locate a particular set of defective genes, make a break in the DNA strands there, and introduce new bits of DNA to take their place. "The beauty of this is that we can rely on a natural process to repair the break," Dr Urnov says. "We let Mother Nature do its work."

Dr Urnov says this process has become much more than just a concept. It has been shown to work on mice and other animals in research labs and is now beginning to be used in clinical trials. Sangamo is already in mid-stage clinical trials for HIV and is hoping to get approval for trials on beta thalassemia, sickle cell disease, and hemophilia.

"Gene editing is a reality," he says. "We can edit the genome of human cells so that they make a new therapeutic protein, or we can knock out a gene in order to have a therapeutic effect."

The next steps in developing gene editing are clear, Dr Urnov says. "We have done a lot of work on mice models, and now we have to translate that to the human setting." At this point, neither Dr Urnov nor anyone else can say when gene editing would be ready for normal clinical use on patients.

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