By Jennifer Williams, MD, as told to Kendall Morgan
Jennifer Williams, MD, is a pulmonologist in pulmonary critical care medicine and a clinical assistant professor in the Department of Medicine, Division of Pulmonary, Allergy & Critical Care Medicine, at Stanford University School of Medicine in Stanford, California. The information here represents her knowledge and experience as a medical professional; Williams was not involved in the development of or clinical trials for depemokimab (Exdensur).
Doctors now recognize asthma as multiple diseases with different types. While everyone with asthma will have some inflammation in the airways, most people can keep it under control with inhaled medicines, including some that act quickly as needed and others that work over longer periods. In up to 10% of people with asthma, the disease is severe and harder to control with those standard medicines.
If your asthma doesn't respond to even the highest doses of a corticosteroid, it may be severe. Severe asthma comes in different types, too.
Severe asthma may be allergic, eosinophilic, or non-eosinophilic. To find out which type of severe asthma you have, your doctor will look at your levels of white blood cells called eosinophils. They can check for eosinophils in your blood or in mucus coughed up from your lungs. Sometimes, they may need to order a biopsy of your lung tissue.
If your severe asthma is eosinophilic and doesn't respond well to other medicines, your doctor might suggest a biologic. Biologics are infused or injected monoclonal antibodies that target specific signaling molecules, known as interleukins, that drive your airway inflammation. You'll have multiple biologic medicines to choose from today, including depemokimab (Exdensur). The FDA approved this biologic medicine for severe asthma in December 2025 based on clinical trials showing it can ease sudden worsening asthma symptoms when taken twice a year as an add-on to standard medicines. Depemokimab was tested specifically in people with severe asthma and high eosinophil counts. This is also known as an eosinophilic phenotype. To learn more about how this new biologic works and who it's for, we spoke with Jennifer Williams, MD, a pulmonologist at Stanford University School of Medicine in Stanford, California.
Who is depemokimab for?
When you enter this more severe category of asthma, when other medicines are really not controlling it, or you're on steroids all the time, that's when you might consider a biologic add-on therapy. This would be an option when you've tried everything else in terms of inhalers. You may have tried triple inhaler therapy without any improvement in symptoms. You may have recurrent exacerbations (sudden worse symptoms) and emergency department visits despite treatment. When you get to this point, then it's a good time to consider biologic therapy options. Depemokimab (Exdensur) is specifically approved for severe asthma in adults and kids 12 and up who have an eosinophilic phenotype.
How does it work?
Biologics are monoclonal antibodies that can neutralize and target the immune cascade. They specifically interrupt the pathway for cytokine signaling, including interleukin-5 (IL-5), IL-4, and/or IL-13. These cytokine signaling molecules regulate your immune responses.
Depemokimab specifically targets IL-5, which plays a role in eosinophils. When you target IL-5, you can block activation of eosinophils. You can block the maturation and survival of these cells. So it really targets this whole cascade, and you can suppress the eosinophils altogether.
What sets depemokimab apart from other biologics?
The whole big buzz over this is that it's a new, ultra-long-acting biologic therapy. So it's an anti-IL-5 antibody. It's approved for add-on maintenance when you've already tried everything else as far as standard options go, and it's twice-yearly dosing. It has this really enhanced IL-5 binding, which gives it a very distinct pharmacokinetic profile such that it has a really long half-life. That means that it stays active in the body much longer.
What are the advantages for patients with severe eosinophilic asthma?
This twice-a-year, or every-six-months, dosing is spectacular. If you look at the other biologic therapies, some of the therapies require you to come in every two weeks. People may have to come in every month or every two months. The longest we typically have had is every eight weeks. Sometimes it's possible to do these as injections at home, but insurance doesn't always cover it. You may have to go to an infusion center. So this twice-per-year dosing is really a big deal in terms of access to care. Overall, if you look at having to take a medication only once every six months, that has many potential benefits.
How well does depemokimab work, and is it safe?
They've conducted studies and looked at people with severe inflammation and eosinophilic asthma. The clinical trials showed a significant reduction in asthma exacerbations and rates with depemokimab compared to placebo, plus standard care. It was also generally well tolerated. So the safety profile is good.
The key thing is that it reduced exacerbations and emergency department visits. It slashes hospitalizations. Reducing hospitalizations is a big one when you look at the overall benefits, not just for patients and their quality of life, but also for resources and the whole overall health care system.
How much does it cost? Will insurance cover it?
Biologic therapy isn't always cheap, depending on your insurance coverage. Since depemokimab is new, it's a good idea to check with your insurance. Insurance coverage can vary with all these biologic therapies. But for severe eosinophilic asthma, this should hopefully be covered for patients by insurance. Many times, even when these medications are covered by insurance, it can still be a struggle for people to afford it. However, financial assistance is also available to help with out-of-pocket costs.
Is this available now, and how can I learn more about whether it's a good treatment option for me?
Yes, it's approved and should be available. Doctors should be aware of this new option. They should be able to answer questions about this new medication. Not only do we discuss options with patients, but I usually give them a little pamphlet. I will print patient-specific material so they're able to read up as well. Reach out to your care team to ask for advice and more information.
Would you recommend switching from another biologic to depemokimab?
I think it's something to think about carefully with your doctor. It depends, and I would say this is when you have to really tailor treatment and communicate well about the options. Many times, if the current treatment is working, I don't always like to switch. Sometimes after we start a biologic, we can peel away some of the other inhaler therapy or come down on other therapies. I wouldn't necessarily suggest everyone switch over to this right away. But if I have a patient that has a barrier to biologic treatment – let's say they live two hours away, and they can't get to an infusion center, and insurance doesn't cover the home injections – this is something I would consider. If treatment adherence is a challenge or you'd just prefer a twice-a-year medicine, then this new treatment option is something I would talk with your doctor about.
Are there any groups with severe eosinophilic asthma for whom this treatment would not be recommended or considered?
It's approved for adults and kids aged 12 and older as an add-on treatment for severe asthma with an eosinophilic phenotype. Its safety hasn't been tested in certain groups, including those who are pregnant. It's important to remember that once you get to the point where you're having severe asthma, it can be lethal. Unfortunately, we've had patients lose their lives over a bad asthma exacerbation. So this is very serious in terms of not just quality of life, but it is also potentially life-saving. Everyone is different, but I think if you fit the profile for severe asthma with an eosinophilic phenotype, this medication should be considered.
FDA approval for any medicine requires careful study in clinical trials. Can you share your insights into the clinical studies?
Depemokimab has been extensively studied through phase 3 clinical trials. Trials showed it reduces asthma exacerbations, and the proportion of patients with adverse events was similar between those receiving the biologic and those receiving the placebo.
Anytime you have a new drug, or a new medication, we have to take into consideration that it's new. We don't have long-term data yet and will have to continue to watch and see how things go. But all indications are that this is a safe and effective new option for treating severe eosinophilic asthma.
Is there anything else you'd like for people with severe asthma and high eosinophil counts to know about this new treatment option?
The concern I always have is sometimes, our asthma patients just try and push through. They may suffer with daily symptoms and exacerbations. Unfortunately, some people are scared of injections, so they're reluctant to seek out or try a biologic. But when you look at the big picture, the reduction in emergency department visits and exacerbations could not just impact your quality of life, but could really be life-saving. So I think this is something that's really worth looking into and having as an option.
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