This year, the Food and Drug Administration approved a new drug for the treatment of allergic asthma. Hailed as a different approach, Xolair is a genetically engineered protein designed to target IgE antibodies in the blood. These antibodies are chemicals in the bloodstream responsible for starting the cascade of events leading to the inflammation and airway constriction typical of an asthma attack. By binding to IgE antibodies, Xolair stops the immune response to an allergen, such as dust mites or animal dander, and prevents asthma from worsening.
This is good news for some asthma sufferers, but not all. In fact, only a small fraction of the 17 million Americans who suffer from asthma will benefit from the drug. Xolair is intended as a second-line therapy for people whose asthma does not respond to inhaled steroids. Also, the drug was approved for use only in adults and teenagers. And studies show Xolair works only in people with moderate to severe asthma triggered by allergens.
Despite its limitations, Xolair appears to work well in its intended audience. In clinical trials, roughly 80%-85% of patients treated with Xolair had no asthma attacks during the six-month study period, compared to 70%-75% of patients treated with a placebo. Patients taking Xolair experienced side effects at a similar rate as patients who received a placebo. The most common side effects included swelling at the injection site (45%), viral infections (23%), and upper respiratory tract infections (20%). Patients taking Xolair were more likely to develop or experience a recurrence of cancer than those patients who received the placebo, but the rates are very low (0.5% compared to 0.2%). The maker of Xolair, Genentech, Inc., is planning long-term studies to look into the relationship between Xolair and cancer.
Before you talk with your doctor about Xolair, keep track of your asthma symptoms for a few weeks. This will help you and your doctor decide whether or not your asthma is under control and at a level you are comfortable with. You'll also need to find out if your asthma is caused by perennial allergens - only a skin or blood test can determine this. Switching to Xolair means frequent doctor's visits; a doctor or nurse must administer the drug through an injection once or twice a month. If you and your doctor decide that Xolair is right for you, be sure to also talk about how to slowly phase out your current medication. And remember, Xolair is not designed to halt an asthma attack once one has started.
November 2003 Update