Nucala (mepolizumab)
An approved treatment for Eosinophilic Granulomatosis with Polyangiitis.
The same compound appears under different names depending on the context. Here is how to identify Mepolizumab wherever you encounter it, plus the key facts at a glance.
- Generic name
- Mepolizumab
- Brand name
- Nucala
- Drug class
- Anti-IL-5 monoclonal antibody
- Manufacturer
- GlaxoSmithKline (GSK)
- How it's taken
- Given as three separate 100-mg subcutaneous injections (300 mg total dose) every 4 weeks.
The first targeted therapy approved for EGPA; for EGPA it is approved for adults only. Mepolizumab blocks IL-5, the hormone that drives eosinophil production, reducing the eosinophilic inflammation and vasculitis that damage blood vessels and organs. The MIRRA trial demonstrated significant increases in remission and steroid reduction.
Where Mepolizumab fits
First biologic therapy approved for EGPA (December 2017) and a cornerstone of modern EGPA treatment. Enables significant corticosteroid reduction in most patients. Now joined by benralizumab (September 2024) as a second IL-5-pathway inhibitor. Both are considered first-line biologic options, with the choice depending on individual patient factors and physician preference.
How Mepolizumab works
In EGPA, the body produces far too many eosinophils, a type of white blood cell that normally fights parasites but in this disease invades blood vessel walls and organs, releasing toxic proteins that cause inflammation, tissue damage, and vasculitis. The overproduction is driven by IL-5, a signaling molecule that tells bone marrow to make eosinophils and keeps existing ones alive and active.
Mepolizumab is an antibody that intercepts IL-5 in the bloodstream before it can reach eosinophils or the bone marrow. Without IL-5 signaling, eosinophil production slows, circulating eosinophil levels drop, and the cells already in tissues lose their survival signal and die off. Over weeks to months, eosinophilic inflammation decreases, blood vessels begin to heal, and organ damage can be prevented.
This eosinophil reduction also allows doctors to taper corticosteroids, which most EGPA patients depend on but which cause serious long-term toxicity including bone loss, diabetes, and weight gain. In the MIRRA trial, mepolizumab significantly increased time in remission and reduced relapse rates compared to placebo.
Mechanism: Humanized monoclonal antibody that binds and neutralizes interleukin-5 (IL-5), reducing eosinophil production and survival to control the eosinophil-driven vasculitis in EGPA
Side effects and safety
The most common side effects include headache (affecting more than 10% of patients), injection site reactions (pain, redness, itching), and hypersensitivity reactions (rare but can include anaphylaxis, angioedema, or bronchospasm). EGPA-specific reactions include rash, itching, flushing, fatigue, and elevated blood pressure in about 6% of patients. Herpes zoster (shingles) has been reported, so your doctor may consider a shingles vaccine. The label also warns that existing parasitic (worm) infections should be treated before starting, that steroid medicines should not be stopped suddenly when Nucala is started and should only be lowered gradually under a doctor's care, and that Nucala should not be used to treat sudden asthma attacks or breathing flare-ups. Overall, mepolizumab was well tolerated in EGPA trials with a safety profile consistent with its use in severe asthma.
This is not a complete list of side effects. Talk to your doctor or pharmacist about what to expect and when to seek medical attention.
Taking Mepolizumab
Given as three separate 100-mg subcutaneous injections (300 mg total dose) every 4 weeks. This is a higher dose than the asthma indication (100 mg). Injections can be administered by a healthcare provider or trained caregiver. Patients should not abruptly stop corticosteroids when starting mepolizumab; reductions must be gradual under physician supervision.
Availability and cost
Only available as the brand-name product.
Help paying for Nucala
Pick your insurance to see which help fits. Drugmaker copay cards can't be used with Medicare, Medicaid or TRICARE; charity funds are the usual route there.
- Copay help
For eligible commercially insured patients, the program pays out-of-pocket costs above $25 per dose, up to $8,000 per calendar year.
For: private insurance · source - Free medicine program
GSK Patient Assistance Program may provide NUCALA at no cost to uninsured or Medicare patients who meet income and other requirements.
For: no insurance, Medicare · source - Insurance and case manager help
Patient Navigators check insurance coverage, explain costs and help with copay program applications. Mon-Fri 8AM-8PM ET.
The official page does not say who qualifies. Ask the program. · source
Good to know: Copay program excludes uninsured patients and Medicare, Medicare Advantage, Part D, Medicaid, Medigap, VA, DoD and TRICARE; copay program line 1-800-691-1939. Free-drug program is run by the separate GSK Patient Access Programs Foundation.
- From a charity · HealthWell FoundationANCA-Associated Vasculitis and Granulomatosis with Polyangiitis fundOpen
Pays for: Copays, premiums or other treatment costs.
Clinical trial results
The Phase 3 MIRRA trial enrolled 136 patients with relapsing or refractory EGPA. Mepolizumab met both co-primary endpoints: significantly increased time in remission and higher proportion of patients achieving remission at weeks 36 and 48 compared to placebo. Relapse rates were significantly reduced. All six secondary endpoints were also statistically significant, including meaningful corticosteroid dose reduction. These results led to FDA approval in December 2017.
Development history
GSK developed mepolizumab in collaboration with the National Institute of Allergy and Infectious Diseases (NIAID). It was first approved for severe eosinophilic asthma in November 2015 and later for hypereosinophilic syndrome in September 2020. The recognition that eosinophil-driven pathology underlies EGPA led to the MIRRA trial. FDA approved mepolizumab for EGPA on December 12, 2017, making it the first targeted therapy ever approved for this rare vasculitis, transforming treatment from corticosteroid dependence to biologic-based management.
Explore Eosinophilic Granulomatosis with Polyangiitis trials
Other Eosinophilic Granulomatosis with Polyangiitis treatments
Common questions about Mepolizumab
▸What is Mepolizumab (Nucala)?
The first targeted therapy approved for EGPA; for EGPA it is approved for adults only. Mepolizumab blocks IL-5, the hormone that drives eosinophil production, reducing the eosinophilic inflammation and vasculitis that damage blood vessels and organs. The MIRRA trial demonstrated significant increases in remission and steroid reduction.
▸How does Mepolizumab work?
In EGPA, the body produces far too many eosinophils, a type of white blood cell that normally fights parasites but in this disease invades blood vessel walls and organs, releasing toxic proteins that cause inflammation, tissue damage, and vasculitis. The overproduction is driven by IL-5, a signaling molecule that tells bone marrow to make eosinophils and keeps existing ones alive and active.
Mepolizumab is an antibody that intercepts IL-5 in the bloodstream before it can reach eosinophils or the bone marrow. Without IL-5 signaling, eosinophil production slows, circulating eosinophil levels drop, and the cells already in tissues lose their survival signal and die off. Over weeks to months, eosinophilic inflammation decreases, blood vessels begin to heal, and organ damage can be prevented.
This eosinophil reduction also allows doctors to taper corticosteroids, which most EGPA patients depend on but which cause serious long-term toxicity including bone loss, diabetes, and weight gain. In the MIRRA trial, mepolizumab significantly increased time in remission and reduced relapse rates compared to placebo.
▸What are the side effects of Mepolizumab?
The most common side effects include headache (affecting more than 10% of patients), injection site reactions (pain, redness, itching), and hypersensitivity reactions (rare but can include anaphylaxis, angioedema, or bronchospasm). EGPA-specific reactions include rash, itching, flushing, fatigue, and elevated blood pressure in about 6% of patients. Herpes zoster (shingles) has been reported, so your doctor may consider a shingles vaccine. The label also warns that existing parasitic (worm) infections should be treated before starting, that steroid medicines should not be stopped suddenly when Nucala is started and should only be lowered gradually under a doctor's care, and that Nucala should not be used to treat sudden asthma attacks or breathing flare-ups. Overall, mepolizumab was well tolerated in EGPA trials with a safety profile consistent with its use in severe asthma.
▸How is Mepolizumab taken?
Given as three separate 100-mg subcutaneous injections (300 mg total dose) every 4 weeks. This is a higher dose than the asthma indication (100 mg). Injections can be administered by a healthcare provider or trained caregiver. Patients should not abruptly stop corticosteroids when starting mepolizumab; reductions must be gradual under physician supervision.
▸Is Mepolizumab FDA approved?
Yes, Mepolizumab (Nucala) is FDA approved (2017) for the treatment of Eosinophilic Granulomatosis with Polyangiitis.
▸Is Nucala approved for EGPA?
Yes. Nucala (mepolizumab) was the first targeted therapy approved for EGPA (eosinophilic granulomatosis with polyangiitis) in December 2017, based on the MIRRA trial showing significant improvements in remission and reduced steroid dependence.
▸How does mepolizumab reduce eosinophils in EGPA?
Mepolizumab blocks IL-5, the hormone that tells bone marrow to produce eosinophils and keeps existing eosinophils alive. Without IL-5, eosinophil levels drop and the eosinophilic inflammation attacking blood vessels decreases.
Sources and references
Every factual claim on this page is drawn from the public sources listed below. Click any reference to open the original document.
- GlaxoSmithKline · December 12, 2017. GSK achieves approval for Nucala for the treatment of EGPA in the US. https://www.gsk.com/en-gb/media/press-releases/gsk-achieves-approval-for-nucala-mepolizumab-for-the-treatment-of-eosinophilic-granulomatosis-with-polyangiitis/
- New England Journal of Medicine. Mepolizumab or Placebo for Eosinophilic Granulomatosis with Polyangiitis. https://www.nejm.org/doi/full/10.1056/NEJMoa1702079
- GlaxoSmithKline. Nucala (mepolizumab) for EGPA. https://www.nucala.com/eosinophilic-granulomatosis-polyangiitis/