Monday, March 10, 2003

A Miracle Drug?

If this works, it could change my life.

Trial Drug Fends Off Peanut Allergies
March 10, 2003 01:10:34 PM PST, HealthScout News

By Amanda Gardner
HealthScoutNews Reporter

MONDAY, March 10 (HealthScoutNews) -- A new drug may ease the worries of the 1.5 million Americans whose peanut allergies have them or their loved ones wondering whether their next meal could be their last.

The experimental medication, called TNX-901, increases the threshold of an allergic reaction from half a peanut to about nine peanuts. While that may not seem like much to peanut lovers, it has been estimated that most of the 50 to 100 deaths each year from peanut allergies occur after ingesting only one or two nuts.

Although a new study on the drug was limited to those with peanut allergies, researchers say it could have a much wider impact.

"This drug may well also apply to other nut allergies and other food allergies, so it could affect 6 to 8 million people," Dr. Donald Leung, co-lead author of the study, said at a news conference Monday.

People with peanut allergies live in a culinary minefield, because their condition forces them to eat defensively. They or their caregivers -- the problem is worse among children, who don't always know better -- must examine ingredient labels with a fine-tooth comb, study the manufacturing process to learn whether a food could possibly be contaminated with peanuts, and ask detailed questions about restaurant fare.

Avoidance has always been the best way to deal with the allergies, but it's not always possible. Lacking that, the most common treatment for someone who has an allergic reaction is to take shots of a lifesaving drug called epinephrine. However, studies have found that only a "small minority" of those with allergies carry the remedy, which is commonly known as an "epipen."

TNX-901 is the first drug that could prevent the reactions in the first place. The Food and Drug Administration granted it fast-track review status last September. This study is what's known as a Phase 2 review, in which the drug is tested for both safety and effectiveness.

Dr. Hugh Samson, co-lead author and professor of pediatrics at Mount Sinai School of Medicine in New York City, estimates that the drug is three to four years from the market, assuming it wins FDA approval. However, legal problems have delayed the third and final part of review process, in which a drug is tested more widely.

"It's not a cure, but it is a buffer that would protect against most accidentally ingested peanut reactions," says Traci Tavares, a spokeswoman for the Food Allergy & Anaphylaxis Network in Fairfax, Va. "Folks with peanut allergy have never had that peace of mind. By boosting the tolerance like this, it staves off what could be a life-threatening reaction and provides the added benefit of safety, so it's very exciting."

"I don't think anyone can accidentally eat nine peanuts," adds Dr. Clifford Bassett, an adult and pediatric allergist at New York University Medical Center and a member of the public education committee of the American Academy of Allergy, Asthma and Immunology (AAAAI). "In those peanut-sensitive individuals, particularly young children, this can save their life. It will be a very, very important medication in that segment of the population."

The research was presented Monday at the AAAAI's annual meeting in Denver, and is also being published in the March 14 issue of the New England Journal of Medicine.

A second study appearing in the journal may help explain why food allergies, including peanut allergies, are on the rise. This research found that children who are exposed to products containing peanut oil, nut oils, and proteins and soy oil through inflamed skin areas (due to eczema or other conditions) may become sensitized to the ingredients. Also, children who drank soy milk or soy formula seemed to have more peanut allergies.

"There's a potential for foods to penetrate the skin even if a toddler is avoiding peanuts in his own diet," says Dr. Gideon Lack, lead author of this study and a consultant in pediatric allergy and immunology at St. Mary's Hospital at Imperial College in London. "His elder brothers and sisters are picking him up while eating peanut butter sandwiches. It's not necessarily consumption of the food that is leading to the allergy."

All a child needs is to just inhale vapors, Bassett adds. In one extreme case, a child Bassett was treating broke out in hives every day when her father came home. It turned out to be a reaction to the nut oils in her dad's shaving cream.

The allergic reaction takes place when the body's immune system tries to protect itself from a substance it mistakenly identifies as harmful. The body creates IgE antibodies against the food, and the antibodies can cause something as minor as an itch or as lethal as stopping breathing.

TNX-901 is a monoclonal antibody, a bioengineered drug that seeks out a specific target. In this case, it binds to IgE and prevents the allergic reactions before they start.

As the investigators on this study acknowledge, it would be completely unethical to purposely induce severe allergic reactions. In this trial, rather than using peanuts, they used peanut flour to elicit less severe, controlled responses. The 81 individuals who completed the study received either a placebo or 150-, 300-, or 450-milligram injections of TNX-901 once a month. Blood levels of IgE were measured throughout the trial.

The higher the dose of TNX-901, the better the protection against an allergic reaction. Most patients in the 300-milligram and 450-milligram groups could eat the equivalent of six and eight peanuts, respectively, before having a reaction. In addition, 24 percent of patients who received the highest dose and 21 percent of the individuals in the 300-milligram group were able to consume the equivalent of 24 peanuts with no reaction. When they did have a reaction, it was generally less severe.

Patients would have to get shots regularly and would still have to watch what they eat, say the investigators. "At this time, the drug is given once a month with injections but we are looking at other protocols," said Leung. "It would have to be ongoing therapy because it's not a cure."

But he added, "Many patients do get allergy shots once a month. It's a perfectly reasonable therapy."

The cost of the drug, and whether it will be covered by insurance, is not known yet, according to its makers.

Litigation over development rights among the three companies involved with the drug -- Tanox Inc., Genentech, and Novartis -- may delay the final phase of trials, however. "We don't know when Phase 3 is going to happen," confirms Michelle DeSantis, a spokeswoman for Tanox in Houston. "We are all in communication. That's always a good sign, and it means that things are moving forward."

I'm trying to imagine or remember what it would be like to eat at a friend's house, to venture into new restaurants without terror. I would still need to give the celery speech. But death by celery just might stop being an option.

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