Allergic to Peanuts? Help on Way
A new, experimental drug can blunt allergic reactions to peanuts, offering the first ray of hope to 1.5 million Americans who are at risk of severe reactions from inadvertent exposure to the commonplace legume, researchers said Monday.
The drug, which blocks an immune system molecule, does not cure peanut allergies but increases tolerance sufficiently that patients no longer need fear dying from accidental ingestion, which can occur from eating such common fare as Chinese food made with peanut oil, gravy thickened with peanut flour, or even cookies made on improperly cleaned baking equipment.
An estimated 50 to 100 Americans die from such reactions each year -- one of the leading causes of allergy deaths. Thousands more are hospitalized, often from consuming the equivalent of half a peanut or less.
On average, people with peanut allergies are exposed once every three to five years, and almost a third will have an extremely serious reaction. In some ways, the growing incidence of such allergies is changing the American landscape. Peanuts can no longer be used in crafts at most schools, and many elementary schools have established special peanut-free lunchrooms. Most airlines no longer serve peanuts, and a few refuse passage to those with peanut allergies because of fear of exposure to airborne particles from other passengers, according to the Food Allergy & Anaphylaxis Network.
Patients taking the new drug, called TNX-901, could tolerate an average of nine peanuts without severe problems, and many could tolerate 24 or more.
So if a person taking the drug has an inadvertent exposure, the results would be much less dire, said Dr. Clifford Bassett of the NYU Medical Center. “Clearly, they wouldn’t eat nine peanuts by mistake,” he said.
“This is a major advance in the management of patients with peanut allergy,” said Dr. Donald Y. M. Leung of the National Jewish Medical and Research Center in Denver, who headed the study presented Monday at a Denver meeting of the American Academy of Allergy Asthma & Immunology. The drug “could not only save lives, but help lift a cloud of fear that people with peanut allergies live under every time they eat.”
The new results are, above all, “about patients,” added Anne Munoz-Furlong, founder and chief executive of the Food Allergy & Anaphylaxis Network. “The potential impact on quality of life is tremendous, not to mention the number of lives it may save.”
Although it has not been tested, the drug could help patients with other allergies as well, because all are mediated by a similar immune mechanism. That would bring the total number of potential beneficiaries to more than 8 million Americans.
But those benefits may, unfortunately, be four years or more in the future. Although researchers are prepared to begin the third and most crucial phase of clinical trials, and the drug has been given fast-track status by the Food and Drug Administration, the drug’s manufacturer, Tanox Inc. of Houston, is locked in a court battle with two other companies that have developed a similar drug. Testing is unlikely to resume until that case is settled, experts said Monday.
The incidence of peanut allergy has been climbing in recent years and another report at the meeting Monday suggests a possible reason: sensitization to peanuts by the use of peanut oils in baby lotions and skin creams.
In a large epidemiological study of British children, Dr. Gideon Lack and his colleagues at St. Mary’s Hospital in London found that the risk of peanut allergy was increased nearly eightfold in children whose parents had used baby lotions and ointments containing peanut oil. If that finding can be confirmed, it might provide an even better way to reduce risks, said Dr. Henry Metzger of the National Institute of Arthritis and Musculoskeletal and Skin Diseases. “Simple avoidance of such exposure might obviate the need for more sophisticated and expensive therapeutic intervention,” he said.
Both studies are being published this week in the New England Journal of Medicine, but they were released early to coincide with their presentation in Denver.
The key to allergic reactions is an immune protein called immunoglobin E, or IgE, which circulates in the blood as a sentinel that alerts the body to the presence of foreign objects. When the system goes awry for reasons that are not yet clear, IgE binds to cells in the nose, throat, skin and gastrointestinal system to provoke a severe reaction called anaphylaxis, or anaphylactic shock, which is characterized by nausea, pain, vomiting, hives, wheezing, itching and other symptoms.
The symptoms can be alleviated by treatment with epinephrine and other antihistamines, but can be fatal in some cases. Many people with peanut allergies -- which for unknown reasons are more severe than other food allergies -- carry epinephrine with them in case of inadvertent exposure. Unfortunately, many who should carry the drug do not, risking their lives, Munoz-Furlong said.
The new drug is a monoclonal antibody, a genetically engineered protein that binds with IgE and removes it from circulation. Researchers have been successfully studying anti-IgEs for about 15 years as a potential treatment for allergic rhinitis and allergic asthma.
The new study is the first to examine its use with peanut allergy.
Leung, Dr. Hugh A. Sampson of the Mt. Sinai School of Medicine in New York and their colleagues studied 82 people, ages 12 to 60, who had demonstrable peanut allergies. At the beginning of the study, they exposed each patent to peanut flour under carefully controlled conditions to determine how much they could tolerate before symptoms began. Most patients began displaying symptoms after exposure to the equivalent of half a peanut, on average.
The 82 patients were then divided into four groups who received either a placebo or one of three different doses of TNX-901. The drug was given as an injection under the skin once a month. For those receiving the largest dose, their threshold for sensitivity increased to an average of about nine peanuts. Nearly a quarter could tolerate 24 peanuts with no symptoms. “That’s a pretty impressive amount,” Sampson said.
Those who still reacted to the peanuts, furthermore, could eat more peanuts without a reaction and reacted less vigorously to the peanuts they did eat.
“This doesn’t make you completely immune, but it makes life easier because you are not looking so carefully at everything you eat,” said Greg Rogers, 49, a residential contractor in Colorado Springs who took part in the study. Before the study, he said, “the smallest minute fragment” of a peanut would produce a severe reaction. Recently, he said he inadvertently ate a cookie bar that had peanuts in it and “the reaction was very minimal.”
The significance of Lack’s results with baby products is less clear. Sampson, who is medical director of the Food Allergy & Anaphylaxis Network, said the group has been unable to identify any baby products containing peanut oil in U.S. stores, although some are available via the Internet.
