Learn About Biological Treatments for Severe Asthma

Understanding Severe Asthma and When Biological Treatments May Be Considered

Asthma affects approximately 25 million Americans, and about 5-10% of those people have severe asthma that doesn't respond well to standard treatments. Severe asthma is different from regular asthma because it continues to cause symptoms and attacks even when patients use high-dose inhaled corticosteroids and other common controller medications. People with severe asthma experience more frequent flare-ups, spend more time in emergency rooms, and face greater limitations in their daily activities.

Doctors typically classify asthma severity based on how much medication is needed to keep symptoms under control. Patients with severe asthma often require multiple medications at maximum doses just to manage basic breathing. This puts them at higher risk for serious complications and can significantly impact their quality of life, school attendance, work performance, and mental health.

Biological treatments, also called biologics or monoclonal antibodies, represent a newer approach to treating severe asthma. Rather than working broadly to reduce inflammation in the airways like traditional corticosteroids do, biologics target specific parts of the immune system that contribute to asthma symptoms in certain patients. This targeted approach allows doctors to treat the underlying causes of asthma in specific subgroups of patients rather than using a one-size-fits-all method.

Several key markers help doctors determine whether a patient might benefit from biological treatments. These include eosinophil counts (a type of white blood cell involved in inflammation), immunoglobulin E (IgE) levels, and specific patterns of symptoms. For example, patients whose asthma is driven by allergies may respond differently to biologics than patients whose asthma is driven by other immune responses. Understanding these differences is crucial because not all severe asthma patients will benefit from every biological treatment available.

Practical Takeaway: Severe asthma requires specialized evaluation beyond standard asthma management. If you or a family member has asthma that remains difficult to control despite using high-dose medications, discussing evaluation for biological treatments with a pulmonologist or asthma specialist may be worthwhile.

How Biological Treatments Work in the Body

Biological treatments function by interrupting specific pathways in the immune system that lead to asthma symptoms and airway inflammation. To understand how these work, it helps to know what happens during an asthma attack. In asthma, the immune system overreacts to certain triggers—whether those are allergens, respiratory infections, exercise, or irritants. This overreaction causes the airways to become inflamed and produce excess mucus, making it difficult to breathe.

Different biological treatments target different parts of this immune response. Some focus on reducing eosinophils, which are white blood cells that promote inflammation in the airways. Others target specific immune proteins called cytokines that send signals telling immune cells to cause inflammation. Still others work by blocking receptors on immune cells, preventing them from receiving inflammatory signals. This variety means that different patients may benefit from different biologics depending on what type of immune response is driving their asthma.

The most commonly discussed biologics for asthma include:

• Anti-IgE monoclonal antibodies - These target immunoglobulin E, an antibody involved in allergic responses. They work well for patients whose asthma is primarily driven by allergies.
• Anti-IL-5 medications - These reduce eosinophil levels by targeting interleukin-5, a key signaling molecule. They benefit patients with eosinophil-driven asthma.
• Anti-IL-4 receptor medications - These block a receptor that helps drive both allergic and eosinophil-driven responses, potentially helping a broader group of patients.
• Anti-TSLP medications - These target thymic stromal lymphopoietin, another immune signaling molecule involved in asthma development.

Because these treatments work through very specific mechanisms, they generally don't work for all severe asthma patients. A patient with severe asthma driven primarily by allergies might see dramatic improvement with an anti-IgE treatment but no improvement with an anti-eosinophil treatment. This is why testing and careful evaluation before starting biological treatment is so important.

Practical Takeaway: Biological treatments work by targeting specific immune pathways rather than broadly suppressing the immune system. Learning which immune pathway may be driving your asthma can help your doctor recommend the most potentially effective biological treatment.

Types of Biological Treatments Currently Available

Several biological treatments have received approval from the Food and Drug Administration (FDA) for severe asthma treatment. Each one has different characteristics, target populations, and administration methods. This guide describes some of the most commonly prescribed options as of current knowledge, though new treatments continue to be developed.

Omalizumab (Xolair) was the first monoclonal antibody treatment approved for asthma and has been used since 2003. This anti-IgE medication works by binding to immunoglobulin E antibodies before they can trigger immune cells. It's particularly useful for patients with allergic asthma and is given as an injection under the skin every 2-4 weeks. Studies show that appropriate candidates experience about a 50% reduction in asthma attacks and oral corticosteroid use.

Reslizumab (Cinqair) is an anti-IL-5 medication administered as an intravenous infusion every 4 weeks. It's designed for patients with eosinophilic asthma, meaning asthma driven by high levels of eosinophils. Clinical trials showed patients receiving reslizumab had about 60% fewer asthma attacks compared to placebo.

Mepolizumab (Nucala) is another anti-IL-5 option available as either a subcutaneous injection or intravenous infusion. It's given every 4 weeks for the subcutaneous form. Real-world data shows that patients with eosinophilic asthma using mepolizumab experience significant reductions in oral corticosteroid requirements, with some patients able to reduce or eliminate corticosteroid use entirely.

Benralizumab (Fasenra) is an anti-IL-5 receptor medication given as a subcutaneous injection. What makes benralizumab unique is its dosing schedule: patients receive injections at weeks 0, 4, and 8, then every 8 weeks afterward. This longer interval between doses may appeal to some patients. Studies demonstrate effectiveness comparable to other anti-IL-5 treatments.

Dupilumab (Dupixent) is an anti-IL-4 receptor medication that blocks a signal needed for allergic and eosinophil-driven inflammation. It's given as a subcutaneous injection every 2 weeks (or every 4 weeks after an initial loading dose). Because it addresses multiple inflammatory pathways, it may help patients whose asthma has both allergic and eosinophilic features.

Tezepelumab (Tezspire) is an anti-TSLP medication that represents a newer approach. It's administered as a subcutaneous injection every 4 weeks. Because TSLP is involved in initiating immune responses, tezepelumab may help a broader population of severe asthma patients regardless of their specific immune profile.

Practical Takeaway: Different biological treatments work through different mechanisms and may be given on different schedules. Your doctor's choice will depend on your specific asthma type, test results, and medical history. Understanding how each works can help you have informed conversations with your healthcare team.

Testing and Evaluation Before Starting Biological Treatment

Before starting any biological treatment, patients undergo thorough testing and evaluation to determine which therapy might work best. This evaluation process is essential because choosing the wrong biological treatment wastes time, money, and doesn't help the patient's symptoms. Healthcare providers typically look at several different factors to make treatment recommendations.

Blood tests form a major part of the evaluation. Doctors measure eosinophil counts—generally measured as cells per microliter