What is Xolair?

Paul M. Ehrlich, MD
Allergy & Immunology
All classes of antibodies look like a lobster, its two claws reacting to antigens such as ragweed or bacteria. The tails of each class are different in that they set off a reaction unique to that class. Allergic immunoglobulin (IgE) antibody tails are buried in the mast cell surface. When their claws attach to an allergen, they cause the mast cell to fire off histamine and other bad stuff.

The first commercial anti-IgE antibody, omalizumab, sold under the name Xolair, was created by genetic engineering, although when something costs $1,000 per month the word "commercial" must be used with a touch of irony.

Xolair acts like a laser-guided smart bomb, seizing allergic IgE antibodies from the blood by their tails. The tail of the IgE remains buried in the mast cell untouched.

At present, the cost of Xolair limits its use to mild-to-severe persistent asthmatics with elevated IgE who have undergone at least one course of steroids. Depending on the patient's weight and IgE level, Xolair is given every two to four weeks for an indefinite period. This reduces IgE levels by 50-90 percent and incidence of asthma by 50 percent, which is much faster than traditional allergy injections. By only lowering the allergic antibody, however, Xolair does not create protective antibodies. Traditional allergy injections do both over a longer period of time. The anti-allergic response is thus slower but more complete.
Asthma Allergies Children: A Parent's Guide

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Asthma Allergies Children: A Parent's Guide

Asthma and allergies are at epidemic proportions. It doesn't have to be that way. Two experienced pediatric allergists tell everything a conscientious parent needs to know about these conditions,...

Xolair (omalizumab) is an IgE blocker prescribed to treat allergy-induced asthma. IgE, short for immunoglobulin E, is a substance produced by your body in reaction to allergens in your environment. If you have allergy-induced asthma, your body creates too much IgE setting off a chain reaction leading to asthma attacks. Xolair treats asthma by blocking the production of IgE. Doctors usually resort to Xolair when other treatment options have failed to fully control asthma. It is part of a class of medications called monoclonal antibodies. It is administered by injection under the skin once every two to four weeks.