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Medications that block interleukin

A number of asthma medications are being studied in large clinical trials. Clinical trials are done in steps, called “phases.”1

  • Phase I: These trials include a small group of people. The goal is to find the safe dose range and study the side effects and safety of a medication.
  • Phase II: These trials are done in a larger group of people. The goal is to see if the medication works and is safe.
  • Phase III: These trials are done with a large group of people. The goal is to confirm that the drug works and to see how frequently side effects occur. These are usually the last step before the Food and Drug Administration (FDA) decides whether to approve the medication.

Several of the asthma medications being studied right now interfere with signaling chemicals called “interleukins” (abbreviated IL).2 Some examples of interleukins are IL-4, IL-5, or IL-13. Interleukins play important roles in allergic asthma:

  • IL-4 and IL-13 are signals to make an antibody called IgE (immunoglobulin E). IgE is responsible for many allergy symptoms, such as wheezing, coughing, swelling, itching, and runny nose.3,4
  • IL-13 has a role in airway narrowing.2
  • IL-5 and IL-13 increase the number of the eosinophils. Eosinophils are a type of white blood cell. About half the people with severe asthma have high eosinophils.5

If the FDA approves these new medications, they could be used to treat people with severe asthma and high eosinophil levels. Inhaled corticosteroids and long-acting beta-agonists are not enough to control asthma for about 10% to 20% of people.6 Approximately 30% to 40% of people with the most severe asthma use oral corticosteroids regularly.7 Even on all these medications, many of these people have serious asthma attacks.8 Additionally, regular use of oral corticosteroids can have serious, permanent side effects.7

Mepolizumab blocks IL-5. Eosinophils need IL-5 in order to develop and survive. Therefore, blocking IL-5 reduces the amount of eosinophils.8 This medication is given by injection every four weeks.

Two Phase III studies of mepolizumab have been done.7,8 They showed that people who took mepolizumab had fewer asthma attacks. They had fewer asthma symptoms, better lung function, and better quality of life. Patients who took mepolizumab needed less of their oral corticosteroid medication.8

GlaxoSmithKline is developing mepolizumab. An application for approval of mepolizumab was sent to the FDA in November 2014.

Dupilumab blocks IL-4 and IL-13. These two interleukins play a number of roles in asthma, so blocking them might improve asthma in several ways. In the studies so far, this medication was given by injection once a week.

A Phase II study was done in patients who had moderate-to-severe asthma and high levels of eosinophils. The patients who took dupilumab had fewer asthma attacks, better lung function, and less inflammation.6 A second Phase II study is being done in patients with moderate-to-severe asthma. Early results from this study showed that taking dupilumab can improve lung function even for people with normal eosinophil levels.9

Regeneron Pharmaceuticals and Sanofi are developing dupilumab. Phase III studies of dupilumab for asthma will begin soon. Dupilumab is also being studied for the treatment of eczema.

Reslizumab blocks IL-5, which eosinophils need in order to develop and survive. Phase III studies are being done in patients with moderate-to-severe asthma and high levels of eosinophils. Early results showed that people who took reslizumab have fewer asthma attacks, better lung function, and fewer asthma symptoms.10

Lebrikizumab and tralaokiumab
Lebrikizumab and tralaokiumab block IL-13. Phase III studies of these medications are underway.

If you want to get involved in clinical trials for asthma, you can learn more here:

  • Database of clinical trials run by that National Institutes of Health
  • Severe Asthma Research Program: A study of adults and children with severe asthma
  • American Lung Association Asthma Clinical Research Centers Network: a not-for-profit network of asthma research centers

Classifying asthma types

It is clear that asthma is not one disease. There are many different types of asthma. A lot of research is being done to figure out the best way to classify asthma.5 One reasons this is important is for selecting the best treatment. Some medications probably work better for some types of asthma than others. Research is needed to answer questions such as:

  • What types of asthma are there?
  • What body processes make each type of asthma different?
  • What is the best way to diagnose each type of asthma?
  • What is the best treatment for each type?

Two terms that are used in this research are “phenotype” and “endotype.” Phenotype means the traits that you can observe or measure.5 Examples in asthma are age that asthma started, eosinophil levels, and amount of lung function. Endotype is the specific body process that leads to the observable traits. One example is allergic asthma, where allergens trigger asthma symptoms.11 However, not all asthma is allergic, so more endotypes need to be found.

Researchers have not come up with an overall system for classifying asthma yet. Several different research groups have come up with their own “clusters” or types of asthma, based on the people they studied.5 It will take more research to fit all the facts together.

Some of the research in this area is focused on “biomarkers” for asthma. Biomarkers are measurable laboratory values that indicate something about a disease. For example, blood pressure is a biomarker used to determine the likelihood of having a stroke. In asthma, examples include IgE as a marker of allergic asthma, and exhaled nitric oxide or eosinophil levels as markers of inflammation.11 Biomarkers or certain patterns of biomarkers are needed to define and diagnose each type of asthma.5

Written by: Sarah O'Brien | Last Reviewed: May 2016.
  1. National Library of Medicine. FAQs. Clinical Trial Phases. Accessed 1/23/15 at:
  2. Kraft M. Asthma phenotypes and interleukin-13--moving closer to personalized medicine. N Engl J Med. 2011;365:1141-1144.
  3. National Heart, Lung, and Blood Institute. Expert panel report 3 (EPR-3): Guidelines for the diagnosis and management of asthma - Full Report 2007. Accessed 11/12/14 at:
  4. Asthma and Allergy Foundation of America. IgE’s role in allergic asthma. Accessed 12/14/14 at:
  5. Wenzel SE. Asthma phenotypes: the evolution from clinical to molecular approaches. Nat Med. 2012;18:716-725.
  6. Wenzel S, Ford L, Pearlman D, et al. Dupilumab in persistent asthma with elevated eosinophil levels. N Engl J Med. 2013;368:2455-2466.
  7. Bel EH, Wenzel SE, Thompson PJ, et al; SIRIUS Investigators. Oral glucocorticoid-sparing effect of mepolizumab in eosinophilic asthma. N Engl J Med. 2014;371:1189-1197.
  8. Ortega HG, Liu MC, Pavord ID, et al; MENSA Investigators. Mepolizumab treatment in patients with severe eosinophilic asthma. N Engl J Med. 2014;371:1198-1207.
  9. Regeneron and Sanofi announce positive results from Phase 2b study of dupilumab in patients with moderate-to-severe asthma [press release]. November 11, 2014. Accessed 1/23/15 at:
  10. Teva’s reslizumab delivers clinically and statistically significant reduction in asthma exacerbations in two pivotal Phase III studies [press release]. September 2, 2014. Accessed 1/23/15 at:
  11. Lötvall J, Akdis CA, Bacharier LB, et al. Asthma endotypes: a new approach to classification of disease entities within the asthma syndrome. J Allergy Clin Immunol. 2011;127:355-360.