When people with allergic asthma encounter a substance they are sensitive to, such as house dust mites or animal fur, this sets off a mechanism in which the body over-produces an ‘antibody’ molecule called immunoglobulin E or IgE.  An excess of IgE can lead to serious harm by triggering the symptoms of allergic asthma – shortness of breath, wheezing and coughing. By reducing the availability of IgE, Xolair (omalizumab) targets a root cause of allergic asthma attacks.  This is explained in more detail below:

When someone breathes in a substance they are allergic to, their body responds to this ‘allergen’ by creating IgE.
 

The IgE flows through the bloodstream, attaching to special inflammatory cells (e.g. mast cells) in the nose and breathing passages.  The immune system is then primed and ready for action.
 

When the person encounters the same allergen, IgE triggers a rapid and aggressive response to what is in reality a relatively harmless substance.
 

IgE attaches to the mast cell, and the ‘arms’ of IgE then attach themselves to the allergen.
 

The IgE and allergens bind together. When a critical mass of allergen bound to IgE is reached, the mast cells break down, releasing chemicals such as histamine into the bloodstream.
 

These chemicals cause the airways to become inflamed, producing the characteristic symptoms of asthma.  In some instances, acute asthma attacks occur.  At their worst, these have the potential to be life-threatening.

• When Xolair® is injected, it selectively targets the IgE antibodies and attaches itself to them.  This prevents the IgE from locking onto a mast cell.
• Xolair® also reduces the number of places on the mast cells where IgE antibodies can attach themselves.
• Much of the IgE is inactivated by Xolair®. As a result, the threat posed by the allergen is reduced as the effect of IgE on the mast cells is reduced.  As a result the threat posed by the allergen is reduced.  Studies have shown that, in people with severe allergy mediated asthma, the number of severe asthma attacks is significantly reduced when Xolair® is used as as add-on therapy to optimum treatment with inhalers.
• Eventually, the IgE and Xolair® are expelled harmlessly from the body.  As the body continues to make IgE, Xolair has to be given regularly every few weeks.
  

Xolair® (omalizumab) was approved by the EMEA on 27th October 2005 as add-on therapy to improve asthma control in adult and adolescent patients (12 years of age and above). Xolair® (omalizumab) is recommended for those with severe persistent allergic asthma who despite daily high-dose inhaled corticosteroids plus a long-acting inhaled beta2-agonist are categorized with the following:

• a positive skin test or in vitro reactivity to a perennial aeroallergen
• reduced lung function (FEV1 <80%)
• frequent daytime symptoms or night-time awakenings
• multiple documented severe asthma exacerbations