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ORLANDO, Fla, Mar 19, 2001 (United Press International via COMTEX) -- Researchers reported Monday that patients who receive biologically engineered drugs designed to grow blood vessels were able to improve exercise function, indicating that the procedure may have a future role in treating people with cardiovascular disease.
In studies presented at the annual meeting of the American College of Cardiology meeting in Orlando, Fla.:
-- Doctors at Duke University and University of Michigan injected the recombinant protein, fibroblast growth factor (FGF-2), in the leg arteries of patients who have difficulty walking distances due to blockages in the leg blood vessels. Ninety days later those patients who received the blood vessel-stimulating protein could significantly outperform patients who received a placebo injection on treadmill tests of exercise capacity.
-- Doctors at William Beaumont Hospital in Royal Oak, Mich., injected a genetically-engineered virus, constructed to produce FGF genetically, into the heart arteries of patients whose exercise was restricted by chest pain. These patients who received the active agent showed improved treadmill function that was significantly better than patients who were given dummy injections.
"These studies are important," said Dr. Valentin Fuster, director of the Cardiovascular Institute at Mt. Sinai Medical Center, New York, "because they represent the first controlled studies that show a positive benefit of these attempts at angiogenesis, creation of new blood vessels." Fuster said that many earlier studies purporting to show benefit of similar injections did not include control groups making objective evaluation of their success difficult to assess.
The new studies, Fuster said, "are first steps that show promise of these treatments. But these are only first steps there is a lot of work that needs to be done before these treatments will be available to patients." In one study, Dr. Robert Lederman, who was formerly at the University of Michigan but now is director of cardiovascular interventions at the National Heart, Lung and Blood Institute in Bethesda, Md., reported that he and colleagues enrolled 190 patients who suffered from intermittent claudication -- leg pain that limited movement -- into the study. About one-third of patients received sham injections, the other patients received either one or two doses of FGF.
The placebo patients achieved a 14 percent improvement after 90 days, compared with a 34 percent improvement in the time one could walk on a treadmill before being stopped by pain by patients getting the single dose of FGF. The patients getting two doses showed a 20 percent improvement that did not reach statistical significance.
"This is the first large, randomized, placebo-controlled, therapeutic angiogenesis study to show benefit in its primary efficacy measure," Lederman said. He said that one of the findings that will be taken further in new trials was that in this cases tow injections of the drug were not better than one.
At Royal Oak, Dr. Cindy Grines, director of cardiac catheterization laboratories at Beaumont, reported similar findings in her gene therapy procedure.
"The trial marks the first scientifically well-controlled clinical study of cardiovascular gene therapy," she said. "A one-time administration during cardiac catheterizations has the potential to be an important addition to current treatment options."
Her study involved 79 patients who received either placebo or two doses of the genetically-modified virus -- its ability to multiply was deleted from the viral genome preventing it from becoming an infectious threat. Patients who received that larger doses of the virus showed a 50 percent improvement in treadmill exercise times at four weeks, and a 45 percent improvement at 12 weeks, compared with 16 percent at four weeks and 21 per cent at 12 weeks for patients who received the placebo infusions.
Dr. Robert Engler, professor of medicine emeritus at the University of California in San Diego and cofounder of Collateral therapeutics, the San Diego company developing the genetically-engineered virus, said the difference between the two procedures was that Grines group was using gene therapy -- creating factories within cells to produce FGF -- while Lederman's group was injecting the protein itself into the blood vessels.
The goal -- production of new blood vessels called "collateral circulation" in medical terms -- is the same, he said.
While Dr. Emile Mohler III, a cardiologist at the University of Pennsylvania School of Medicine, said the studies showed promise, "unless we address risk factors, such as smoking, diabetes control, cholesterol levels, then these improvement in therapy will have little effect on the disease."
"This is a good news story," Fuster said. "We are on the right track."
By ED SUSMAN, UPI Science News
Copyright 2001 by United Press International.
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