Score another one in the loss column for gene therapy. Cambridge, MA-based Genzyme said yesterday at a medical meeting that its gene therapy for people with peripheral artery disease failed in a clinical trial to help them regain some mobility.
The trial—one of the largest in the field of gene therapy—enrolled 289 patients who were injected with either a placebo or a low, medium, or high dose of Genzyme’s gene therapy treatment, researchers said at the American College of Cardiology meeting in Orlando, FL. The treatment, designed to deliver a copy of a gene called HIF1a, was supposed to help stimulate the growth of new blood vessels around clogged arteries in the legs, improving circulation and allowing people with severely limited mobility to walk for longer periods of time.
Gene therapy, as I explained in this feature on Genzyme last week, is about altering viruses to carry copies of genes into cells, where they can replace missing or faulty genes at the root of certain types of disease. This technique rode a wave of scientific enthusiasm in the early 1990s, leading to the formation of more than 100 biotech companies. But there are still no FDA-approved gene therapies on the U.S. market. Genzyme, which has been in the gene therapy business since 1991, is pulling the plug on this particular program, although it has other gene therapies in development for Parkinson’s disease and macular degeneration, said Erin Emlock, a company spokeswoman. Last month, researchers also reported some promising results from a gene therapy trial against HIV.
“Gene therapy with intramuscular administration of HIF-1 alpha is not an effective therapy for patients with peripheral artery disease,” said Mark Creager, director of the vascular center at Brigham & Women’s Hospital in Boston. He’s the investigator who presented results from the trial at the cardiology meeting.
The main goal of the trial, which began in 2005, was to see if the Genzyme treatment could increase the time patients could walk on an inclined treadmill before disabling pain or fatigue caused them to stop. Researchers examined patients after six months, and followed for them two years.
Researchers saw that patients in the trial were able to walk 30.4 percent longer after six months on placebo, which was about the same as patients on the low dose. That was actually better than the people who went 23 percent longer on the medium dose. There was a slight improvement observed for patients on the high dose, who walked 34.7 percent longer after six months. But that improvement over the placebo group wasn’t statistically significant, researchers said.
Safety didn’t appear to be a problem in the Genzyme trial. The rates of heart attack, stroke, and cancer were similar among patients who got placebo or the experimental treatment.
