What is Benralizumab (Fasenra)?
Benralizumab, marketed as Fasenra, is a prescription biologic medication used as an add-on treatment for severe eosinophilic asthma and eosinophilic granulomatosis with polyangiitis (EGPA). It is a humanized immunoglobulin G1 (IgG1) monoclonal antibody. As a biologic, it's derived from living organisms. Benralizumab is used in patients aged 6 and older for severe eosinophilic asthma, and in adults for EGPA, when standard treatments are insufficient. It is not for acute asthma attacks.
Mechanism of Action: How Benralizumab Targets Eosinophils
Benralizumab works by rapidly and near-completely depleting eosinophils, a type of white blood cell, from the blood and tissues. Eosinophils play a key role in the inflammation seen in conditions like severe eosinophilic asthma and EGPA, often driven by the cytokine Interleukin-5 (IL-5).
Targeting the IL-5 Receptor Alpha (IL-5Rα)
Benralizumab targets the alpha subunit of the IL-5 receptor (IL-5Rα), which is found on eosinophils and basophils. By binding to IL-5Rα, benralizumab serves two main functions:
- It blocks IL-5 from binding, thus inhibiting the signaling that promotes eosinophil survival and maturation.
- Its structure is modified (afucosylated) to enhance binding to FcγRIIIa receptors on natural killer (NK) cells. This interaction allows NK cells to recognize eosinophils bound with benralizumab and eliminate them through antibody-dependent cell-mediated cytotoxicity (ADCC). This mechanism leads to significant eosinophil depletion.
Approved Uses and Indications
Benralizumab is approved as an add-on maintenance therapy for specific severe conditions where eosinophils are implicated.
- Severe Eosinophilic Asthma: For patients aged 6 and older with severe asthma and elevated blood eosinophils that isn't controlled by existing medications. It helps reduce exacerbations and may decrease the need for oral corticosteroids. It is not for sudden asthma symptoms.
- Eosinophilic Granulomatosis with Polyangiitis (EGPA): Approved for adult patients with this rare autoimmune disorder.
Investigative Use in Other Eosinophilic Conditions
Benralizumab is being studied for its potential use in other conditions involving eosinophils, including COPD with an eosinophilic component, eosinophilic gastritis/duodenitis, and hypereosinophilic syndrome.
Comparing Benralizumab with Other Biologics
Benralizumab is one of several biologic options for severe eosinophilic asthma. It differs from others in its target and mechanism. For details on comparisons with other biologics like Mepolizumab and Dupilumab, including targets, mechanisms, and effects on eosinophil counts, consult {Link: droracle.ai https://www.droracle.ai/articles/45980/which-is-more-effective-benralizumab-vs-dupilumab-}. Selecting a biologic depends on individual patient factors and a clinician's assessment.
How Benralizumab Is Administered
Benralizumab is given as a subcutaneous injection. The administration schedule is determined by a healthcare professional based on the specific condition being treated. Adults and children aged 12 and older can potentially self-administer at home after training. Common injection sites include the thigh, abdomen, or upper arm.
Potential Side Effects
Common side effects of benralizumab include headache, sore throat, fever, and reactions at the injection site. More serious reactions can occur, such as hypersensitivity or allergic reactions, which may include rash, hives, swelling, or anaphylaxis. Patients should be monitored for these. Patients with parasitic infections should have them treated before starting benralizumab.
Conclusion
Benralizumab is a valuable targeted therapy for severe eosinophilic asthma and EGPA, offering a distinct mechanism of action through eosinophil depletion via ADCC. It provides an effective add-on treatment to improve symptom control and reduce exacerbations. While generally well-tolerated, patients should be aware of potential side effects and work closely with their healthcare provider for safe and effective use. Continued research into benralizumab and other biologics holds promise for patients with challenging inflammatory conditions. For more detailed information on drug uses, precautions, and side effects, consult an authoritative medical resource such as {Link: Mayo Clinic website https://www.mayoclinic.org/drugs-supplements/benralizumab-subcutaneous-route/description/drg-20406682}.
