Breakthrough Study: Medication Protects Patients with Peanut Allergy
A new medication, the first of its kind, could help most people with peanut allergy avoid life-threatening allergic reactions, according to a report in the March 14 issue of the New England Journal of Medicine. A research team led by principal investigators Hugh Sampson, MD, Director of the Elliot and Roslyn Jaffe Food Allergy Institute at Mount Sinai, and Donald Leung, MD, PhD, of the National Jewish Medical and Research Center in Denver, found that treatment with a specific antibody raised the average threshold at which study participants had reactions to peanuts from about half a peanut to almost nine peanuts. Researchers estimate that most of the 50 to 100 annual fatal reactions to peanuts occur after an allergic person accidentally eats the equivalent of just one to two nuts.
| Dr. Hugh Sampson |
The study - and research on the effectiveness of the allergy drug - were presented Monday in Denver to the American Academy of Allergy, Asthma and Immunology. They will be published Thursday in the New England Journal of Medicine, which released them Monday on its Web site. The findings have received wide coverage in the consumer press and on television. Dr. Sampson appeared on The Today Show on Tuesday. "This medication is a big deal because it's the first time that we have an active form of therapy for food allergy," said Dr. Sampson. "In the past, all we could do was tell patients to avoid the allergen. Now there is a way of helping people who may die from ingestion accidents. They eat peanuts when they don't mean to, which we know causes many of the deaths from peanut allergies." In a person who is allergic, IgE is the molecule produced by the immune system that is miscued. Instead of providing protection against invading parasites, it responds inappropriately and binds to a group of cells called mast cells, triggering the allergic reaction. Allergic reactions can range from nausea and itching to anaphylactic shock and death. TNX-901, the treatment used in this study, is a genetically engineered antibody (made by Tanox Inc.) that binds to the IgE molecule and prevents it from binding with mast cells and triggering the allergic response. Blocking IgE is considered a major advance because it inhibits the allergic response at an earlier stage than other medicines, effectively stopping it before it begins. A slightly different anti-IgE molecule has shown promise in treating severe hay fever and asthma. "Our results indicate that the anti-IgE antibody could become the first preventive medicine for peanut allergies," said Dr. Leung. "If future studies bear out this initial promise, anti-IgE could not only save lives, but help lift a cloud of fear that people with peanut allergies live under every time they eat." Approximately 1.5 million people in the U.S. have peanut allergy, the leading cause of severe allergic reactions. Each year, thousands of people rush to hospital emergency rooms, and approximately 50 to 100 people die after accidentally eating peanuts. The only means of preventing an allergic reaction is strict avoidance, which can be difficult to impossible, especially since food labels do not always mention tiny amounts of peanuts that are found in some foods. Existing medications, including epinephrine, antihistamines, bronchodilators, and charcoal pills, are taken only after the peanuts have been eaten and are not always effective. In the study, 82 people, aged 12 to 60, with severe peanut allergy were given four injections at monthly intervals of either a placebo or one of three doses of TNX-901. TNX-901 was well tolerated with no significant side effects. Blood levels of IgE were measured before the injections began and periodically throughout the test. TNX-901 raised patients' threshold sensitivity to peanut flour in a dose-responsive manner. Many patients still reacted to peanuts even after the injections, but on average, they could eat more peanuts without a reaction and reacted less vigorously to the peanuts they did eat. Significantly, nearly a quarter of the patients receiving the highest dose of TNX-901 consumed the equivalent of 24 peanuts with no reaction. "We believe that patients would have to continue the injections for the benefits to persist, and they still would need to be careful about what they eat," said Dr. Sampson, who reports that Mount Sinai and others will continue to test the treatment in phase III clinical trials. "The drug has been fast-tracked by the FDA," he notes, "but it will be three to four years at best before it could receive final approval and be available to the public." Posted March 11, 2003
Hugh A. Sampson MD Director of Mount Sinai's Jaffe Food Allergy Institute
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