Severe asthma is a chronic respiratory condition that significantly impacts a person's quality of life. Unlike milder forms of asthma.

Biological Treatments for Severe Asthma: A Comprehensive Guide

Severe asthma is a chronic respiratory condition that significantly impacts a person's quality of life. Unlike milder forms of asthma, severe asthma persists despite high-dose inhaled corticosteroids and other standard therapies, often leading to frequent exacerbations, hospitalizations, and a reliance on oral corticosteroids, which carry significant side effects. For individuals living with this challenging condition, biological treatments have emerged as a targeted and highly effective option.

Understanding Severe Asthma

Asthma is characterized by inflammation and narrowing of the airways, making breathing difficult. In severe asthma, this inflammation is more pronounced and resistant to conventional treatments. It's often associated with specific types of inflammation, or "phenotypes," which can be identified through various tests. Recognizing these phenotypes is crucial for determining the most appropriate and effective treatment strategy.

Symptoms of severe asthma can include persistent coughing, wheezing, shortness of breath, and chest tightness, often worsening at night or with activity. These symptoms can be debilitating, limiting daily activities and affecting overall well-being.

What Are Biological Treatments (Biologics)?

Biological treatments, commonly known as biologics, are a class of medications derived from living organisms. For severe asthma, biologics are monoclonal antibodies designed to target specific molecules or pathways involved in the inflammatory processes that drive asthma symptoms. Unlike traditional asthma medications that offer a broad anti-inflammatory effect, biologics provide a more precise and targeted approach, aiming to interrupt the specific inflammatory cascade relevant to an individual's asthma phenotype.

These therapies work by blocking key inflammatory mediators, such as certain interleukins or immunoglobulin E (IgE), which play a significant role in the development and persistence of severe asthma. By neutralizing these specific components, biologics can reduce airway inflammation, decrease asthma exacerbations, and improve lung function.

Types of Biological Treatments for Severe Asthma

Several biological treatments are approved for severe asthma, each targeting a different inflammatory pathway:

Omalizumab (Xolair)

Omalizumab was the first biologic approved for asthma. It targets immunoglobulin E (IgE), an antibody central to allergic reactions. By binding to free IgE in the bloodstream, omalizumab prevents IgE from attaching to mast cells and basophils, thereby reducing the release of inflammatory mediators. It is typically used for patients with moderate to severe persistent allergic asthma that is inadequately controlled by inhaled corticosteroids.

Mepolizumab (Nucala)

Mepolizumab targets interleukin-5 (IL-5), a cytokine that plays a crucial role in the growth, activation, and survival of eosinophils. Eosinophils are a type of white blood cell often elevated in severe asthma patients with an "eosinophilic phenotype." By blocking IL-5, mepolizumab reduces eosinophil levels in the blood and airways, thereby decreasing inflammation and exacerbations. It is approved for severe eosinophilic asthma.

Reslizumab (Cinqair)

Similar to mepolizumab, reslizumab also targets IL-5 to reduce eosinophil counts. It is administered intravenously and is indicated for the add-on maintenance treatment of severe eosinophilic asthma in adult patients.

Benralizumab (Fasenra)

Benralizumab is another biologic that targets the IL-5 pathway, but it works differently. Instead of blocking IL-5 itself, benralizumab binds directly to the IL-5 receptor on eosinophils, leading to their rapid and near-complete depletion through a process called antibody-dependent cell-mediated cytotoxicity. This makes it a highly effective option for patients with severe eosinophilic asthma.

Dupilumab (Dupixent)

Dupilumab targets the alpha subunit of the interleukin-4 receptor (IL-4Rα), thereby blocking both IL-4 and IL-13 signaling. These two cytokines are key drivers of type 2 inflammation, which underlies many cases of severe asthma, including eosinophilic and oral corticosteroid-dependent asthma. Dupilumab can reduce exacerbations and improve lung function in a broad range of severe asthma patients.

Tezepelumab (Tezspire)

Tezepelumab targets thymic stromal lymphopoietin (TSLP), an upstream cytokine that initiates multiple inflammatory pathways associated with asthma. By blocking TSLP, tezepelumab can reduce inflammation across various asthma phenotypes, including those not typically characterized by high eosinophil counts. It is approved for severe asthma regardless of the patient's phenotype or biomarker levels.

Who Is a Candidate for Biologics?

Biological treatments are not suitable for everyone with asthma. They are generally reserved for individuals with severe asthma who continue to experience persistent symptoms and frequent exacerbations despite optimal adherence to conventional high-dose inhaled corticosteroids and other controller medications. A pulmonologist or allergist/immunologist will typically evaluate several factors to determine eligibility, including:

• The severity and frequency of asthma symptoms and exacerbations.


• The presence of specific inflammatory biomarkers, such as elevated blood eosinophil counts or high IgE levels.


• The patient's asthma phenotype (e.g., allergic, eosinophilic).


• Previous response to standard asthma treatments.

This comprehensive assessment ensures that the most appropriate and effective biologic is selected for the individual patient's specific needs.

Benefits and Considerations

For eligible patients, biological treatments can offer significant benefits, including:

• A substantial reduction in the frequency and severity of asthma exacerbations.


• Improved lung function and better control of daily asthma symptoms.


• Decreased reliance on oral corticosteroids, thereby reducing associated side effects.


• An overall improvement in quality of life.

However, it is important to consider that biologics are administered via injection (either subcutaneously or intravenously) and may cause side effects, such as injection site reactions, headaches, or, rarely, more severe allergic reactions. They represent a long-term commitment and require ongoing medical supervision. The decision to start a biologic therapy is a shared one between the patient and their healthcare provider, weighing the potential benefits against any risks or lifestyle considerations.

The Importance of Specialist Consultation

If you or someone you know is struggling with severe asthma, consulting with an asthma specialist, such as a pulmonologist or an allergist/immunologist, is paramount. These specialists have the expertise to accurately diagnose severe asthma, identify its specific phenotype, and determine if biological treatments are a suitable option. They can guide patients through the selection process, monitor treatment efficacy, and manage any potential side effects, ensuring the best possible outcomes for managing this complex condition.