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Gene Therapy May Ease Angina

Helps stimulate blood vessel growth, study says

MONDAY, Feb. 25, 2002 (HealthDayNews) -- People diagnosed with angina, the persistent and dangerous chest pain caused by narrowing of the heart arteries, now must either take medication indefinitely or undergo bypass surgery or the artery-opening procedure called angioplasty.

However, a new treatment is on the horizon, researchers say -- gene therapy to improve blood flow by stimulating the growth of new blood vessels.

In a trial of 79 people with angina, gene therapy improved physical performance and caused no adverse side effects, says a report in tomorrow's issue of Circulation.

That trial is a significant step toward asking for U.S. Food and Drug Administration (FDA) approval of the treatment, says Dr. Robert L. Engler, a leader of the study and a developer of the therapy. A larger-scale study has started in the United States, another is about to begin in Europe, and "we believe those two trials will give us enough information to submit to the FDA for approval," he says.

The story began in 1993, says Engler, who was chief of the research division at the Veterans Administration San Diego Health Care System, when Dr. H. Kirk Hammond, another cardiologist at the center, discovered a specific virus would deliver genes to the heart. He then identified a gene that stimulates angiogenesis, the process of blood vessel formation.

American drug companies showed no interest, so Hammond, Engler and a few others started their own company, Collateral Therapeutics. They hooked up with Berlex Laboratories, a subsidiary of a European company, to push the technology.

"We performed the appropriate toxicology studies, applied to the FDA, and performed the trial," Engler says.

In gene therapy, a genetic fix is delivered to a patient, usually with a virus as the delivery agent, to fix a malfunction.

The trial tested performance on a treadmill, a marker of endurance, heart capacity and blood flow, in the 79 patients with mild to moderate angina; half had already had heart attacks. Their results were compared to those of 19 similar patients who did not get the gene.

At the start of the study, treadmill endurance was the same for both groups, roughly nine minutes. Performance of those who got the gene improved by 1.7 minute, compared to an improvement of 0.7 minutes for those who didn't. The sickest patients showed the best response. In many cases, the effect was as great as that seen after bypass surgery or angioplasty, Engler says. In addition, there were no adverse side effects.

The American study, which began last October, will include 450 people. The European trial, with the same number of participants, will start soon, Engler says.

The gene therapy restores a process that somehow goes wrong in angina, he says. Normally, the heart keeps making new blood vessels. "In angina, the process stops for reasons that are not understood," Engler says. "The gene therapy stimulates the process to occur."

The therapy will be "focused on patients with ordinary angina, not end-stage patients, those with mild to moderate angina," he says. "It will hopefully reduce the need for medication, and will be an adjunct to or replacement for bypass surgery and angioplasty." All that would be required would be a single infusion.

The potential market is large, says Chris Reinhard, president of Berlex Laboratories -- 6 million patients in the United States, 18 million worldwide, "from 2 to 3 percent of the population in any industrialized country."

It will take 18 to 24 months to conduct the two trials, Reinhard says, and "it generally takes six months to a year to get FDA approval."

"This is the first cardiovascular gene product to reach clinical trials," he says. "We want to provide cardiologists with a new tool to fight coronary artery disease."

What To Do

Prevention is better than any cure, and the way to reduce the risk of angina and other cardiovascular conditions is clear: a diet low in fat and high in fiber; no smoking; 30 minutes of physical activity four or five days a week; and keeping blood pressure under control.

Gene therapy holds promise, but a few treatments have ended in the death of the patients. This study is small, and the results would have to be bolstered by the larger studies.

You can learn all about angina from the American Heart Association or the National Heart, Lung, and Blood Institute.

To learn about gene therapy, try the University of Pennsylvania.

SOURCES: Interviews with Robert L. Engler, M.D., former chief, research division, Veterans Administration San Diego Health Care System; Chris Reinhard, president, Berlex Laboratories, San Diego; Feb. 26, 2002, Circulation
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