New Biologic Drugs Target the Root of Asthma
Asthma is a chronic disease affecting more than 25 million people in the United States. Patients suffering from asthma feel shortness of breath, chest tightness and experience coughing and wheezing. Asthma symptoms are due to inflammation and spasms of the lungs’ airways and can be triggered by infections, exercise, allergens, strong smells, and cold air. There is no cure for asthma, but there are many effective treatments. For decades, asthma treatment has been focused on the complications of asthma, including inflammation, as well as relief of acute symptoms. Common medications include inhaled steroids, leukotriene antagonists and bronchodilators. However, despite wide use of these medications, many patients still experience continued symptoms and uncontrolled asthma. Fortunately, new therapies are now available which target specific root causes of asthma, not just the effects. These therapies are called biologics.
The Role of Biologics in Asthma Treatment
A biologic is a medication that is created from something living (such as microorganisms or cells). This is in comparison to the traditional synthetic or chemically based drugs with which we are most familiar, and commonly use.
Biologics are distinctive because they are able to recognize and bind to specific cells in the body associated with a specific disease. Thus biologics are very specialized and can customize disease treatment.
The biologic basis of asthma is complicated. There are numerous, multifaceted interactions between cells in the body and the chemicals these cells release. Biologics for asthma are revolutionary new injectable treatments that attack some of the specific players in the asthma game. Asthma biologics are antibodies, which work by blocking the cells and chemicals that cause inflammation and airway constriction before they can cause damage. Currently, asthma biologics have two distinct targets: IgE antibodies and eosinophils.
Biologics Targeting IgE
The first biologic approved to treat asthma was omalizumab (Xolair). It is an injectable medication indicated for allergic asthma; it targets IgE antibodies, which are involved in producing allergic reactions. Allergies and asthma go hand in hand and patients with allergic asthma tend to have elevated levels of IgE antibodies circulating in their bodies. IgE antibodies cause cells to release chemicals which lead to airway swelling and narrowing and thus asthma symptoms. Omalizumab itself is an antibody and works by grabbing IgE so it is no longer available to interact with allergic cells. As a result, omalizumab reduces asthma exacerbations, decreases asthma symptoms and decreases the use of traditional asthma medications including steroids. Targeting IgE antibodies has been an effective way to treat allergic asthma and use of omalizumab has been incorporated into the asthma management guidelines for severe asthmatics.
Biologics Targeting Eosinophils
Eosinophils are type of white blood cell. Normally, the role of these cells is to fight infections—specifically, parasitic infections. However, eosinophils are found in high numbers in the airways of asthmatic patients. Eosinophils play an active role in asthma by releasing chemicals that damage the airway lining and cause constriction of the airway. Reducing the number of eosinophils in the body reduces asthma symptoms, and a new treatment has been developed to do this for patients with severe asthma. This biologic treatment, mepolizumab (Nucala), is an injectable medication that works by lowering eosinophil levels. As a result, it can reduce rates of asthma exacerbations and allow patients to lower the doses of their daily inhaled steroid medications.
At this time, the use of biologics is recommended for patients with severe asthma. Patients whose asthma is not controlled on inhaled steroids or combination medications are likely to benefit from these treatments. Biologics can be considered a game changer for these patients, as conventional treatment options have not been effective for severe asthmatics. Many new biologic treatments are coming down the pipeline, including those that focus on even more targets in the asthma pathway. We can anticipate more and more of these progressive, specialized treatments in the next few years.