By MICHELLE L. BRANDT
Medical center researchers are testing a novel gene therapy technique to treat critical limb ischemia, a painful and potentially life-threatening disease caused by severely reduced blood flow in the legs. The research is the first placebo-controlled study of its kind.
Critical limb ischemia, or CLI, is a severe obstruction of the arteries that leads to reduced blood flow, severe pain and skin sores in the extremities. The disorder, which most commonly stems from atherosclerosis (the buildup of plaque inside arteries), affects about 10 percent of adults over the age of 55. Treatment options are somewhat limited. Many patients are non-responsive to medication or have too many health risks to undergo vascular surgery. In severe cases, amputation may become necessary.
"This is a group of patients we worry about a lot," said Stanley Rockson, MD, professor of medicine, who is leading the Stanford portion of the multicenter study. "Identifying an alternative therapy for the disorder could have tremendous implications."
The study will test the use of hepatocyte growth factor to stimulate vessel formation and re-establish blood flow in limbs with blocked arteries. Unlike other gene therapies, which rely on partly disabled viruses to carry genes into human cells, the growth factor will be injected directly into the ischemic tissue of the legs. Rockson said this unusual method should reduce some adverse effects sometimes caused by other gene therapy techniques.
The researchers’ aim is to determine whether the growth factor can be delivered in a safe, effective way. Rockson said past studies have suggested the delivery of growth factors can help improve blood flow, heal ulcers, minimize pain and reduce the need for amputation. "This represents a new potential avenue for patients with little recourse besides amputation and death," he said.
The randomized, double-blind trial will include 100 CLI patients who are not considered candidates for standard therapies to repair their arteries. In the study, half of the patients will receive a series of intramuscular injections of the growth factor and half will receive a placebo. All participants will be monitored for 12 months.
Stanford is seeking volunteers over the age of 40 to participate in the trial.
Participants must have vascular disease in their legs that has caused chronic symptoms such as ulcerations, gangrene and leg pain at rest. Participants also must not have a family history of cancer or diabetic retinopathy. Interested volunteers should call 498-4460.
The study is sponsored by AnGes Inc., a Maryland-based company that specializes in the research and development of gene-based agents for therapeutic use.
Stanford Report, July 23, 2003