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by Neil Gershman, M.D.
A completely new type of allergy drug (we’ll refer to it as Anti-IgE) is about to hit the market. However, this drug will not be used for allergies in general for at least the next few years. Anti-IgE, a synthetic protein that removes allergy-causing molecules from the blood, will initially be approved for treating the most severe allergic asthmatics that are not well controlled on currently available medication. Because we already have such good medications for asthma, it is a rare situation when a patient cannot be controlled (especially when that severe patient is being treated be an asthma specialist). Consequently, Anti-IgE will start out with a small target audience.
For these most severe asthmatics, especially those who have positive allergy tests and have had to be hospitalized despite proper treatment, this drug may be of significant value. In several studies Anti-IgE has been shown to decrease the number of severe attacks by about 50%. If a hospitalization for asthma, let’s say, costs 10 or 15 thousand healthcare dollars, then Anti-IgE might be worth it’s weight in gold (it’s probably going to be a lot more precious than that!). But you should note that the asthma attacks did not go down to zero, showing that this drug is not a cure for asthma. The drug may work even better in children, but approval for this age group is not imminent.
So what’s all the fuss about? Why is this drug on TV and in the venerable New York Times? It turns out that IgE, the molecule that’s eliminated by this new drug, is very important in several types of allergy. These include anaphylactic types of food, insect and drug allergy, as well as allergic rhinitis or hay fever. Since the biological mechanisms involved in certain types of food, insect, and drug allergy are almost exclusively IgE-mediated (as opposed to allergic rhinitis and asthma which are more complicated), Anti-IgE might be close to a cure in these diseases.
Indeed, a recent report in the New England Journal of Medicine suggests that severely peanut allergic people would able to tolerate a significant accidental peanut ingestion while on a similar Anti-IgE drug. The author of the article, Dr. Donald Leung, spoke at a recent national allergy meeting about this research. He warned the audience of allergy doctors and scientists that this research was in too early a stage to be applied to “real world” medicine. He also stressed that this anti-IgE molecule was not exactly the same drug as the one that’s about to be approved, and that it might be used to prevent severe reactions from accidental, not purposeful eating of a large amount of an allergy-inducing food.
Other interesting scenarios in which to use this drug would be as a pre-surgical treatment for latex allergic people (in case of accidental exposure) or as a pretreatment for a drug allergy when there are no alternative drugs are available for a life-threatening infection (as an alternative to desensitization). Neither of these scenarios has been tested.
Also, no studies to date have looked at insect allergy with Anti-IgE. The drug was proven to work in allergic rhinitis, but the effects were not miraculous. My opinion would be that other treatments such as nasal steroids and allergen immunotherapy injections are similarly effective.
The big issue with Anti-IgE is, however, as soon as the drug is stopped, the allergy returns. So, we are talking about a lifetime of therapy in most cases. This, in turn, leads to the problem of cost. Although the drug company hasn’t decided how to price the drug, a good guess would be around one thousand dollars a month.
So, we are left with a lot of interesting possibilities. But until this drug has a long-term safety record, until more of these scenarios are tested in properly controlled trials, and until the price comes down, Anti-IgE should only be used in severe allergic asthma which is not controlled on multiple medications. We allergists are as excited as the public about this new drug, but we will all have to wait and see what this drug can and can't do.