Healthcare Industry News: Cook
News Release - April 26, 2006
Trial of Gene Therapy for Peripheral Arterial Disease Under Way at StanfordVolunteers Needed to Test Whether Experimental Drug May Improve Walking and Relieve Pain
STANFORD, Calif.--(HSMN NewsFeed)--April 26, 2006--Alex Miczo has dreams of someday walking the 2,167-mile Appalachian Trail. But for now, the 64-year-old computer scientist from Mountain View can't even walk around the block without feeling a knife-like pain stabbing into his calves.
"I'd dearly love to walk that trail," said Miczo. But for the past six years, the leg pain, often followed by numbness in his feet and ankles when he walks, has severely limited his mileage. "When the pain sets in, I have to throw in the towel."
Miczo, who was finally diagnosed last year with peripheral arterial disease, or PAD, a hardening of the arteries in the legs, is taking part in a gene therapy trial at the Stanford University School of Medicine to test an experimental new drug for the treatment of this often painful and debilitating disease. Researchers are searching for more volunteers for the study either diagnosed with PAD or experiencing undiagnosed discomfort in the legs that occurs with exercise.
"We're trying to improve the ability of these patients to walk by improving blood flow to their legs," explained John Cooke, MD, PhD, professor of cardiovascular medicine, who has specialized in studying PAD for more than 20 years. "That will improve both their lifestyle and their health."
A common but often undiagnosed disorder, PAD affects an estimated 8 million to 12 million people in the United States, many who go years assuming they're suffering from arthritis or just the aches and pains of getting older before finally getting diagnosed. Essentially, PAD is caused by a disease process similar to the one that causes heart disease. A buildup of fatty deposits along the walls of the arteries limits the supply of oxygenated blood to the arms or legs causing restricted use, fatigue, and/or pain. But rarely do people connect these symptoms with the term "blocked arteries."
"Even doctors often don't recognize PAD, which is a shame," said Cooke who is leading the trial at Stanford. The multicenter study will test the experimental drug, Ad2/HIF-lalpha/VP16, which is designed to encourage the growth of healthy new blood vessels to improve circulation to the legs. A total of about 300 patients at 35 sites in the United States, England and Germany will take part in the study, which is sponsored by the Cambridge-based biotechnology company Genzyme Corp. Cooke has no financial ties to the corporation.
Researchers say they are taking particular care to explain the risks of volunteering to prospective participants given the checkered history of trials involving potential gene therapies, most notably the death of a volunteer enrolled in another study in Pennsylvania in 1999. "We have a much better understanding of potential adverse affects," said Cooke, adding, "This is a very complicated study because we are extensively screening."
Potential volunteers will be required to undergo a thorough evaluation before being accepted into the study, Cooke said. Many with cancer or any other disorder that might be negatively affected by the growth of new blood vessels have already been deemed ineligible. The formation of new blood vessels is often associated with the growth of solid tumors.
Once accepted into the study, volunteers will have the new drug injected into the muscle on 20 sites on each leg, and then undergo treadmill testing over a two-year follow-up period to see whether, as hoped, leg pain decreases while walking distances increase. One out of every four patients will receive a placebo. Varying doses of the drug will be administered to the others.
To develop the experimental drug for this study, scientists used a gene transfer technique that packages the gene responsible for triggering proteins that grow new blood vessels into a modified version of the cold virus. After injection, the modified cold virus is designed to ferry the gene into the body's cells where it triggers a process called "angiogenesis" -- new blood vessel growth.
"We're just trying to encourage what is already a natural process," said Cooke, who added that although the body often grows new blood vessels on its own to bypass diseased vessels, the size and number are not usually significant enough to alleviate the negative side effects of blockage.
"It's really a quality-of-life issue," said Randall Harada, MD, a research physician at Stanford working on the study. "People with PAD have less motivation, less energy and less enjoyment because of their limited walking. Although we do not yet know if this new drug will help patients with PAD, we believe this study is an important step in discovering effective therapies for the many who are affected."
This is the second phase of a three-phase study. The first phase was successfully completed with 30 PAD patients in Boston. Eligible volunteers range in age from 40 to 80. For more information on volunteering for the study contact Homa Tavana at (650) 724-1024.
Stanford University Medical Center integrates research, medical education and patient care at its three institutions -- Stanford University School of Medicine, Stanford Hospital & Clinics and Lucile Packard Children's Hospital at Stanford. For more information, please visit the Web site of the medical center's Office of Communication & Public Affairs at http://mednews.stanford.edu.
Source: Stanford University Medical Center
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