Biologic Treatment for Severe Asthma

The term “biologic” is used for medications and other healthcare products that are made from living animals, plants, or cells, instead of through a chemical process. Biologics include a wide range of products, such as vaccines and blood products, as well as medications used to treat certain medical conditions (e.g., insulin for diabetes).

All of the biologic medications currently used for asthma are antibodies, a kind of protein that occurs naturally in our bodies. By designing and producing a biologic antibody, we can tailor it to help control disease; for instance, by shutting down lung inflammation or other processes that lead to asthma attacks.

Biologics fall into the category of “controller” medications – that is, they are used to help the body gain long-term control of everyday asthma symptoms and to reduce the overall risk of an asthma attack. Like other controllers, biologics are not used for the rapid relief of an asthma attack – that is a job for short-acting reliever medications.

For more information on how controller and reliever medications work together, and details on the available options, please see Asthma Canada’s booklet Breathe Easy™: Medications.

If your doctor is considering using a biologic to treat your asthma, the biologic would be added to the reliever and controller medications you are currently taking. Biologics do not replace these medications, although some people may find that they are able to reduce the dose of their controller medication after several doses of a biologic. Please note that you should only reduce the dose of your controller if your doctor tells you to do so.

Biologics are not for everyone. They are intended to be used by people with Severe Asthma that is difficult to control with standard reliever and controller medications. This is why your doctor will probably try a variety of reliever and controller medications before suggesting a biologic.

We sometimes think of asthma as a single medical condition. However, when scientists looked closely at the way inflammation happens in the airways, they found that there are actually different types of asthma, involving different parts of the immune system. Because biologics are designed to work very specifically, your doctor will need to figure out what type of asthma you have in order to choose a biologic that will work well for you.

Right now, biologics are available in Canada that target two types of Severe Asthma: allergic (IgE-mediated) asthma and eosinophilic asthma.

Allergic asthma is a common condition where triggers (allergens) in the environment like pollen, house dust mites, or pet dander can provoke asthma attacks and symptoms. If you have this kind of asthma, your body produces large amounts of a protein called IgE (immunoglobulin E). When you encounter one of your allergic triggers, this IgE causes the release of immune mediators such as histamine, which are responsible for the airway inflammation and constriction (tightening) that are present during an asthma attack.

If you have allergic asthma, and it is severe enough that you cannot manage it using standard controllers and relievers, your doctor might consider a biologic medication that blocks the action of IgE. Before starting treatment, you will need to have a blood test to confirm that you have a particular level of IgE in your bloodstream.

Some people with asthma produce a higher than normal number of a particular kind of inflammatory cell called an eosinophil. These cells play an important role in causing airway inflammation and increasing the risk of an asthma attack. If your doctor suspects you have this form of asthma, you will likely be asked to give a sample of blood, and possibly also a sample of sputum (the material you cough up from your lungs), in order to test whether you have a high level of eosinophils.

For people with eosinophilic asthma who are unable to manage their symptoms with standard relievers and controllers, there are biologic medications available that reduce the body’s production of eosinophils. This lowers the number of eosinophils and the level of inflammation in the lungs, which can reduce the risk of asthma attacks.

Each of these two conditions can occur on its own, but they can also overlap. In particular, it is common for people with allergic (IgE-mediated) asthma to also have high levels of eosinophils, so they could possibly be treated with a biologic that targets either side of the immune reaction. In overlapping cases, your doctor might choose which biologic to try based on whether the allergic or the eosinophilic side of the asthma is causing more concern.

If you only have one of the conditions – that is, allergic asthma without eosinophils, or eosinophilic asthma without an allergic side – your doctor will prescribe the biologic that is most appropriate for that type.

Some people with asthma produce a higher than normal number of a particular kind of inflammatory cell called an eosinophil. These cells play an important role in causing airway inflammation and increasing the risk of an asthma attack. If your doctor suspects you have this form of asthma, you will likely be asked to give a sample of blood, and possibly also a sample of sputum (the material you cough up from your lungs), in order to test whether you have a high level of eosinophils.

For people with eosinophilic asthma who are unable to manage their symptoms with standard relievers and controllers, there are biologic medications available that reduce the body’s production of eosinophils. This lowers the number of eosinophils and the level of inflammation in the lungs, which can reduce the risk of asthma attacks.

The most serious side effect that can happen with biologic treatments is the development of an allergic or allergic-like reaction. These reactions are rare, but in some cases, they can be serious. Symptoms can include breathing difficulties, faintness/dizziness, rash, swelling, and itching. Allergic reactions most often occur right after the injection, but sometimes symptoms can start several days later.

If your doctor is considering a biologic to treat your asthma, be sure to ask about the risks of an allergic reaction, the most severe of which is called anaphylaxis, and find out what symptoms to watch for and what to do if they occur.

People taking biologics have also reported some less serious but more common side effects, which can include:

• Headache
• Pain, redness, itching, and/or a burning sensation where the injection was given
• Increased risk of infections such as colds, flu, and urinary tract infections

This is not a complete list of the side effects that may happen with biologics; if your doctor is considering a biologic for you, please make sure to ask about the possible side effects that could happen with the specific medication you will be using.