Mepolizumab

Severe Asthma

Mepolizumab is used along with other asthma medicines for the long-term treatment of severe asthma in adults and children 6 years of age and older. It is specifically indicated for patients whose asthma is not well-controlled by their current medications and is characterized by an eosinophilic phenotype. This means the asthma is associated with high levels of eosinophils, a type of white blood cell that can cause airway inflammation.

Chronic Rhinosinusitis with Nasal Polyps

This medication is used in adults to treat chronic rhinosinusitis with nasal polyps. It is typically prescribed as an add-on treatment when corticosteroid nasal sprays have not been effective enough at managing symptoms.

Eosinophilic Granulomatosis with Polyangiitis (EGPA)

Mepolizumab is used to treat adults with EGPA, a rare autoimmune condition that causes inflammation of the small and medium-sized blood vessels.

Hypereosinophilic Syndrome (HES)

It is used to treat adults and children 12 years of age and older who have HES. This is a group of rare disorders where the body produces too many eosinophils, which can lead to organ damage if left untreated.

Important Considerations

• Mepolizumab is a maintenance treatment and is not a rescue medication. It should not be used to treat sudden breathing problems or an acute asthma attack.
• It is intended for long-term use to help prevent symptoms and reduce the frequency of flare-ups.

Mepolizumab is a type of medication known as an interleukin-5 (IL-5) antagonist. It is a monoclonal antibody specifically designed to target and bind to IL-5, which is a signaling protein in the immune system responsible for the growth, activation, and survival of eosinophils.

Eosinophils are white blood cells that normally help the body fight infections. However, in people with certain conditions, the body produces an excessive amount of these cells. When eosinophil levels are too high, they can cause significant inflammation and swelling in the lungs, nasal passages, and other tissues, leading to symptoms like breathing difficulties or flare-ups.

Mepolizumab works by attaching itself to the IL-5 protein. This action prevents IL-5 from binding to its receptors on the surface of eosinophils. By interrupting this signaling process, the medication helps to:

• Reduce cell production: It limits the number of new eosinophils produced by the bone marrow.
• Lower cell survival: It decreases the lifespan of eosinophils already circulating in the body.
• Decrease inflammation: By lowering the concentration of eosinophils in the blood and tissues, the drug reduces the underlying inflammation that causes symptoms.

Common Side Effects

The most frequently reported side effects of mepolizumab include:

• Headache
• Injection site reactions, such as pain, redness, swelling, itching, or a burning sensation
• Back pain
• Fatigue or feeling tired
• Sore throat or sinus infections
• Stomach or abdominal pain
• Muscle spasms or pain

Serious Side Effects

Some patients may experience severe side effects that require immediate medical care. These include:

• Allergic reactions: Serious allergic reactions (anaphylaxis) can occur after an injection, sometimes hours or days later. Symptoms include swelling of the face, tongue, or mouth; breathing problems; fainting; dizziness; hives; or rash.
• Shingles: There is an increased risk of developing shingles (herpes zoster) while using this medication. Symptoms typically include a painful skin rash with blisters.

Hypersensitivity Reactions

Serious allergic reactions, including anaphylaxis, have been reported following the administration of mepolizumab. These reactions can occur within hours of the injection or may be delayed for several days. Symptoms of a severe reaction may include swelling of the tongue or throat, difficulty breathing, fainting, dizziness, or a widespread rash. If a hypersensitivity reaction occurs, treatment is typically stopped.

Acute Symptoms and Rescue Use

Mepolizumab is a maintenance treatment and is not designed to treat acute asthma symptoms, acute bronchospasm, or status asthmaticus. It should not be used as a rescue medication for sudden breathing problems.

Corticosteroid Tapering

Systemic or inhaled corticosteroids should not be discontinued abruptly upon starting mepolizumab. If a reduction in corticosteroid dose is appropriate, it must be done gradually and under the supervision of a healthcare professional to avoid withdrawal symptoms or a return of underlying conditions.

Parasitic Infections

Because mepolizumab reduces eosinophil levels, it may weaken the body's response to certain parasitic (helminth) infections. Existing parasitic infections should be treated before starting therapy. If a patient becomes infected while using mepolizumab and does not respond to anti-parasitic treatment, the medication may be interrupted until the infection resolves.

Herpes Zoster

Cases of herpes zoster (shingles) have occurred in individuals receiving mepolizumab. Healthcare providers may consider shingles vaccination before starting treatment if it is medically appropriate for the patient.

Pregnancy

The safety of mepolizumab during pregnancy has not been fully established in humans. While animal studies have not indicated a high risk of birth defects or pregnancy loss, there is insufficient data from human studies to confirm its safety. Because mepolizumab is a monoclonal antibody, it is likely to cross the placenta and reach the fetus, particularly during the second and third trimesters.

If you are pregnant or planning to become pregnant, your doctor will help you decide if the benefits of treating your condition outweigh the potential risks to the fetus. There is a pregnancy exposure registry that monitors outcomes for individuals who take this medication while pregnant.

Breastfeeding

It is not known if mepolizumab passes into human breast milk or if it has any effect on a nursing infant or milk production. Because many medications can be present in breast milk, it is important to talk to a healthcare provider about the risks and benefits of breastfeeding while using this medication.

Available Forms

Mepolizumab is provided as a solution for injection under the skin. It is available in the following delivery systems:

• Prefilled Autoinjector: A single-dose, disposable device for use by patients or caregivers after receiving proper training.
• Prefilled Syringe: A single-dose syringe with a needle, which may be used by patients, caregivers, or healthcare providers.
• Single-dose Vial (Powder): A vial containing a powder that a healthcare professional must mix with sterile water before administration.
• Single-dose Vial (Liquid): A vial containing a liquid solution intended for administration by a healthcare professional.

FDA Approval and Indications

Mepolizumab was first approved by the U.S. Food and Drug Administration (FDA) in 2015. It is a humanized interleukin-5 antagonist monoclonal antibody indicated for the following uses:

• Severe Eosinophilic Asthma: As an add-on maintenance treatment for patients aged 6 years and older whose asthma is not adequately controlled by their current medications.
• Chronic Rhinosinusitis with Nasal Polyps (CRSwNP): As an add-on maintenance treatment for adult patients who have not responded adequately to nasal corticosteroids.
• Eosinophilic Granulomatosis with Polyangiitis (EGPA): For the treatment of adult patients with this rare autoimmune condition.
• Hypereosinophilic Syndrome (HES): For the treatment of adults and pediatric patients aged 12 years and older who have had the condition for at least six months without an identifiable non-blood-related cause.

Regulatory Safety Information

There are currently no boxed warnings or Risk Evaluation and Mitigation Strategies (REMS) required by the FDA for mepolizumab. However, the regulatory labeling includes several important safety warnings:

• Hypersensitivity Reactions: Serious allergic reactions, including anaphylaxis, have been reported. These reactions can occur within hours or sometimes days after the injection.
• Herpes Zoster Infections: Shingles infections have occurred in patients receiving the drug. Healthcare providers may recommend vaccination before starting treatment.
• Corticosteroid Reduction: The FDA advises that patients should not stop or reduce their systemic or inhaled corticosteroids abruptly when starting mepolizumab. Any changes to steroid dosages must be done gradually under medical supervision.

Mepolizumab is also recognized in the FDA table of pharmacogenomic biomarkers for its specific application in patients with an eosinophilic phenotype.

Factors Influencing Cost

Several factors can affect the total price of mepolizumab treatment:

• Insurance Coverage: Your out-of-pocket costs will depend on your specific health insurance plan, including your deductible, copayment, and coinsurance levels.
• Formulation: Mepolizumab is available as a prefilled autoinjector, a prefilled syringe, or a vial for reconstitution. The cost may differ depending on which form your doctor prescribes.
• Administration Site: If the medication is administered by a healthcare professional in a clinic or hospital setting, there may be additional fees for the office visit and the injection procedure.

Generic Availability

Mepolizumab is a biologic medication currently available only under the brand name Nucala. There is no generic or biosimilar version available at this time, which generally means the cost remains higher than for medications with generic alternatives.

Financial Assistance

The manufacturer may offer patient assistance programs or copay cards to help eligible individuals with commercial insurance reduce their out-of-pocket expenses. Patients without insurance or those with government-funded insurance (such as Medicare or Medicaid) may have different eligibility requirements for financial support programs.