ORLANDO, Florida—Jeffrey Chamberlain, PhD, outlined the 4 different types of gene therapy for treating Duchenne muscular dystrophy (DMD) at the Gene Therapy and Gene Editing Symposium which took place on the second day of the CureDuchenne 2022 FUTURES National Conference

These are: gene replacement therapy, where an adeno-associated virus (AAV) is used to deliver a small version of the DMD gene to the body; gene modification therapy, such as exon skipping, where the endogenous DMD gene is modified; gene editing, or CRISPR/Cas 9, which modifies or repairs the structure of the DMD gene to improve its function; and gene knock-down, where a mutant gene that is harmful is inactivated.

Dr. Chamberlain is a professor at the University of Washington School of Medicine and director of the Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, both in Seattle. At the symposium, he also talked about the history of gene editing.

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“Gene therapy is a concept that was first proposed almost 40 years ago,” Dr. Chamberlain said, “but it’s taken quite a long time to bring it into the clinic.” This is because there are many challenges associated with it in DMD, he explained.

Read more about gene therapy and other experimental therapies for DMD.

The main challenge is the size of the DMD gene and the packaging capacity of the AAV vectors. Another challenge is tissue targeting, where only muscle tissues should be targeted by gene therapy. Unknowns about the correct AAV dose, the durability of the response to gene therapy, and immunity against the AAV vector itself are other challenges associated with gene therapy in DMD.

“Mid- and late-stage clinical trials are helping address these issues,” Dr. Chamberlain said. He explained the different products being developed by Pfizer, Sarepta, and Solid Biosciences to overcome these challenges and how the companies joined forces to better understand the serious adverse events caused by gene therapy in patients with DMD.

Dr. Chamberlain’s talk was followed by a presentation by representatives of different companies developing gene therapies for DMD.


Gene therapy and gene editing symposium. CureDuchenne 2022 FUTURES National Conference; May 29, 2022; Orlando, FL.