Gene therapy — inserting new genes into cells to treat disease — first became a reality in the early 1990s. Now past its earliest years and into its adolescence, the science has progressed along two major pathways.
The first seeks to define the best way of delivering genes inside the shell of a defanged virus, with the precise type of viral shell dependent on the target tissue. Viral delivery of genes is highly effective but carries some risk of eliciting an unwanted response from the immune system.
The second pathway seeks to perfect gene transfer to tissues without the use of viruses, a technique that may be some-what less effective but is probably safer.
MDA is funding research groups using both approaches and is supporting a gene therapy trial using viral delivery in boys with Duchenne muscular dystrophy.
An MDA-supported gene therapy trial in a form of limb-girdle MD that results from a deficiency of the alpha-sarcoglycan protein recently received a go-ahead from the Recombinant DNA Advisory Committee. This green light is the first step in the approval process for the gene therapy trial in the United States.
The first U.S. human gene therapy trial directed at Duchenne muscular dystrophy (DMD),was launched in March at Columbus (Ohio) Children's Hospital. The project will soon move to a second stage, with a $2.5 million grant from MDA, and matching funds from Asklepios Biopharmaceutical (www.askbio.com) of Chapel Hill, N.C.
In this second stage, researchers will test in animals the safety and effectiveness of delivering miniaturized genes for the dystrophin protein, encased in the shell of an adeno-associated virus, via the bloodstream, so that multiple muscles can be reached.
Results from phase 1 of the clinical trial are expected this spring. Investigators tested the safety of injecting the laboratory-engineered gene therapy compound directly into a single muscle in six boys with the disease.
The $2.5 million grant to AskBio is the largest MDA has ever awarded to a for-profit company. MDA gave AskBio $1.6 million for the first phase of the trial.
In October, Jon Wolff, an MDA grantee at the University of Wisconsin-Madison, with that institution and the biotech company Mirus (www.mirusbio.com), announced the group now has a European patent for a method of delivering "naked" genes (not encased in a viral shell) to muscle tissue via the bloodstream. The group already has a patent for this process in the United States.
Mirus' lead gene therapy compound for muscular dystrophy is being developed with Transgene (www.transgene.com) of Strasbourg, France. The announcement says a clinical trial is planned for 2008.