It’s far too early to say whether gene therapy can treat Duchenne muscular dystrophy, a deadly genetic disease. But the first clinical data have arrived, with Sarepta Therapeutics today reporting encouraging preliminary results from three patients.
Sarepta (NASDAQ: [[ticker:SRPT]]), of Cambridge, MA, is conducting an early-stage study of its experimental treatment known as AAVrh74.MHCK7.micro-Dystrophin. The first trickle of data should be viewed with several caveats, not least of which is that they do not indicate whether the therapy can help stave off the decline of muscle function that characterizes Duchenne. The data only show that the three patients—an extremely small sample size—are producing more of a protein called dystrophin, which helps build muscle and is lacking in the disease because of a mutation in the dystrophin gene. The patients are also making less of an enzyme, called creatine kinase (CK), which is an indicator of muscle damage. Yet the study’s lead investigator, a Duchenne and gene therapy expert, is extremely bullish as to what the results portend.
“These are really remarkable results and very consistent. We’re seeing improvement in every parameter so far we can measure,” says Jerry Mendell (pictured), director of the gene therapy center at Nationwide Children’s Hospital in Columbus, Ohio. “We’re very pleased at this point and would hope that this continues.”
In a note to investors Tuesday morning, Leerink analyst Joseph Schwartz said the data “should position Sarepta as the leader in this field.” Sarepta shares surged 44 percent, to over $151 apiece, midday Tuesday.
The patients, each between four and seven years old, were evaluated only three months after they received the gene therapy. The treatment is a single infusion meant to provide long-lasting, if not permanent effects (there are currently no cures for the disease). Sarepta’s gene therapy is amenable to about 70 percent of Duchenne patients with specific types of genetic abnormalities. (Sarepta also has a second, different type of gene therapy in early testing meant for all Duchenne patients.)
Sarepta is reporting today that, based on two different diagnostic tests, its gene therapy is helping these three patients produce an average of either 38.2 percent or 53.7 percent of normal levels of what’s known as “micro dystrophin” after two months. Micro dystrophin is a smaller version of the dystrophin gene that is easier to deliver into patients’ cells. Sarepta is one of at least three companies—along with Solid Biosciences (NASDAQ: [[ticker:SLDB]]) and Pfizer (NYSE: [[ticker:PFE]])—using gene therapy to deliver the micro dystrophin gene into patients’ bodies. To put that in perspective, in animal tests, that level of micro dystrophin expression is “correlated not with arresting decline but actually with improved function,” says Sarepta CEO Doug Ingram. (The approved therapies for Duchenne only slow its progression.)
Sarepta also reported that patients’ 90-day muscle biopsies showed
