Benralizumab

• Severe Eosinophilic Asthma
• Asthma Maintenance Treatment
• Eosinophilic Airway Inflammation
• Corticosteroid-Sparing Therapy

Benralizumab is a humanized monoclonal antibody used as an add-on maintenance treatment for severe eosinophilic asthma. This biologic medication targets the interleukin-5 receptor alpha and provides a unique mechanism for reducing eosinophil-driven inflammation.

Mechanism of Action

Benralizumab is an IgG1-kappa monoclonal antibody that binds directly to the interleukin-5 receptor alpha (IL-5Rα) on the surface of eosinophils and basophils. Unlike other anti-IL-5 therapies that neutralize circulating IL-5, benralizumab binds to the receptor and, through enhanced antibody-dependent cell-mediated cytotoxicity (ADCC), induces direct, rapid, and nearly complete depletion of eosinophils. This afucosylated antibody has enhanced binding to FcγRIIIa receptors on natural killer cells, leading to apoptosis of eosinophils. The resulting profound eosinophil reduction decreases airway inflammation and improves asthma control.

Available Formulations

Benralizumab is available as a solution for subcutaneous injection in prefilled syringes and autoinjectors containing 30 mg/mL. The medication requires refrigeration and should be brought to room temperature before administration. Patients can self-administer after proper training.

Medical Uses

Benralizumab is FDA-approved as add-on maintenance treatment for patients aged 12 years and older with severe asthma and an eosinophilic phenotype. It is not indicated for treatment of acute bronchospasm or status asthmaticus. Clinical trials demonstrated significant reductions in annual asthma exacerbation rates, improved lung function, and reduction in oral corticosteroid use in patients with severe eosinophilic asthma (blood eosinophils ≥300 cells/µL).

Dosing Guidelines

The recommended dose is 30 mg administered subcutaneously once every 4 weeks for the first three doses, then once every 8 weeks thereafter. The injection can be given in the upper arm, thigh, or abdomen. It should not be injected into areas where the skin is tender, bruised, erythematous, or hardened. Patients should continue their existing asthma medications; systemic corticosteroid doses should not be reduced abruptly upon initiating benralizumab.

Important Safety Information

Hypersensitivity reactions, including anaphylaxis, have been reported with benralizumab. Patients should be observed after administration. The medication should be discontinued if severe hypersensitivity occurs. Benralizumab should not be used to treat acute asthma symptoms or acute exacerbations. Patients should not discontinue systemic or inhaled corticosteroids abruptly upon initiation of therapy. Helminth infections should be treated before starting therapy, and treatment with benralizumab should be interrupted if infection occurs during treatment.

Drug Interactions

No formal drug interaction studies have been conducted with benralizumab. Based on its mechanism as a monoclonal antibody, it is not expected to undergo hepatic metabolism or interact with cytochrome P450 enzymes. The medication may be used concomitantly with inhaled corticosteroids, long-acting beta-agonists, and other standard asthma therapies. No dosage adjustments are required for concomitant medications.

Special Populations

There are no adequate data on benralizumab use in pregnant women. Animal studies did not show fetal harm at exposures significantly higher than clinical doses. It is unknown whether benralizumab is excreted in human breast milk; the developmental and health benefits of breastfeeding should be considered along with the mother's need for treatment. Safety and efficacy have been established in patients aged 12 years and older. No dose adjustment is required for elderly patients, though limited data are available in this population. No dose adjustment is needed for hepatic or renal impairment.