To understand anti-IgE therapy and its role in treating allergies and asthma, it is first important to understand the relationship between allergies and the body's immune system.

IgE antibodies are key players in allergic reactions. IgE antibodies prompt other cells (mast and basophil cells, among others) to begin the complex chain reaction that culminates in allergy and asthma symptoms such as coughing, sneezing, watery eyes, and shortness of breath.

Traditionally, allergies and allergy-induced asthma are managed using medications that treat IgE-mediated symptoms once they have already begun in the body. While each treatment has its use, none of the available therapies provides a preventive measure against the binding of IgE to mast cells.

A novel, more targeted approach to the treatment of allergies and allergy-induced asthma is called anti-IgE therapy. This new class of medications holds great promise for people with moderate-to-severe allergies and asthma because it is specifically designed to block IgE from initiating the allergic response, potentially preventing the onset of symptoms before they start.

The first medication in this class, called Xolair® (omalizumab), has been approved by the FDA for the treatment of moderate-to-severe persistent asthma in patients age 12 and older whose symptoms do not respond to standard treatment.

Xolair® is the first biologic treatment that targets allergic asthma. "Biologic" means it uses genetically engineered mammalian proteins, rather than chemicals. Physicians say it breaks the "allergy cascade" — the chain of events that lead to asthma. Specifically, it stops the allergic reaction before it begins, by attaching itself to IgE antibodies and preventing them from causing the allergic reactions that set off asthma symptoms.

Xolair is not a medicine you swallow or inhale; it is an injection given two to four times a month. The effects last as long as you continue the injections. For some of those who have taken it, Xolair offers a way to control allergies and asthma when other options have not worked.

Candidates for Xolair must be 12 years of age or older with moderate-to-severe allergic asthma triggered by year-round allergens in the air as confirmed by a dictor using a skin or blood test, whose symptoms persist even when using inhaled corticosteroids. Frequently, such patients will have the following characteristics:

• Daily asthma symptoms
• Need for a bronchodilator every day
• Two or more times a week when asthma symptoms worsen, either quickly or gradually
• Asthma symptoms that disturb sleep one or more nights a week
• Below-normal peak flow meter readings (less than 80%)

Researchers are testing Xolair in patients, both children and adult, who have food and pollen allergies, but the product is not yet approved for treating these disorders.

Despite its potential, it's important to note that anti-IgE therapy is not a cure for asthma or allergies, and that in some cases other medications may still be needed. Additionally, while many people who have taken Xolair have been exposed to allergens without experiencing symptoms, it is advised that people still continue to maintain their allergen avoidance program.