Fighting over Peanuts

By Christine Gorman

Every medical advance comes with at least some caveats, but last week's news about an experimental treatment for people who are allergic to peanuts includes more than the usual paragraph of fine print. For starters, it's clear that the treatment is not a cure for peanut allergy. Not only might you have to take it for the rest of your life, but you would still have to avoid peanuts. And if it ever becomes available (a big "if," given the frosty relations among the companies involved in its development) the treatment is likely to be quite expensive--at least $10,000 a year.

But since about 1.5 million Americans suffer from peanut allergy and more than 150 of them die each year, usually from accidental exposure to peanuts or peanut products, any advance in the field is worth exploring.

The news last week was that a compound called TNX-901, given to patients with peanut allergy, has proved effective in ratcheting down the body's allergic responses to the legume. Patients with severe peanut allergy who were injected with the highest doses of TNX-901 could be exposed to the equivalent of nine peanuts without developing a severe reaction according to a study reported in the New England Journal of Medicine. It was conducted by a team of doctors led by researchers from the National Jewish Medical and Research Center in Denver, Colo., and the Mount Sinai School of Medicine in New York City. "We still need to nail down the right dose," says Dr. Donald Leung of National Jewish. But he and his partners believe that TNX-901 could be the first real treatment for peanut allergy ever developed.

As anyone who has lived with a peanut allergy knows, it can be very dangerous. Unlike hay fever, an even more common allergy, an allergic reaction to peanuts can quickly kill you. In a process called anaphylaxis, the body overreacts to the point that its airways clamp down, which can lead in some cases to suffocation. Fortunately, anaphylaxis can be reversed--if it is recognized in time. (The EpiPen, a portable adrenaline shot that patients suffering an attack can give themselves before they get to the emergency room, has proved to be a lifesaver.)

Now you might be inclined to think that a 1-out-of-10,000 chance of death isn't so bad. But here's the tricky thing about peanut allergy: there's no way to predict who is prone to anaphylaxis and who isn't. Many people who develop anaphylaxis previously suffered only a mild reaction after consuming peanuts. Couple that with the fact that it is increasingly difficult to avoid peanuts--which, in addition to obvious sources like peanut butter and peanut oil, may be found in plain chocolate candies, sunflower seeds and other foods because of cross-contamination in processing--and you can see why doctors are eager to find better treatments.

Enter a molecule with the ungainly name of immunoglobulin E, or IgE. One of many biological compounds produced by the body's immune system, IgE apparently evolved to help our ancestors fight off parasitic worms. These days, however, parasitic worms aren't so common--especially in urban areas--and IgE has become something of a nuisance. The higher the level of IgE in your body, the more likely you are to develop allergic reactions to otherwise harmless stuff, like peanuts. IgE-triggered allergies also seem to play a role in certain cases of asthma. Over the past decade, researchers have developed specialized compounds, called monoclonal antibodies, to block the action of IgE and dampen the body's allergic reactions.

As you've probably guessed, TNX-901 is an anti-IgE antibody. Here's where the business complications come in. Three companies--Genentech, Tanox and Novartis--have been working in partnership since 1996 to develop anti-IgE therapies. Their lead anti-IgE product, called Xolair, could be approved for the treatment of allergic asthma by the Food and Drug Administration as early as this summer. When Tanox decided to develop TNX-901 on its own, Genentech and Novartis objected, saying that would dilute their development efforts. Last October arbitrators ruled that Tanox cannot be the sole developer of TNX-901, leaving what looks like a promising treatment in legal limbo.

Could Xolair take TNX-901's place? Not without a lot of new testing. "The problem is that they are not identical drugs," says Dr. Hugh Sampson of Mount Sinai. "We don't know how the doses compare." Any doctor who prescribes Xolair off label to deal with your peanut allergy could well be gambling with your life.

So for now, at least, folks with peanut allergy have to do what they have always done: avoid peanuts in any form, keep an EpiPen on hand and try to lead as normal a life as possible.