FDA Approves Treatment for Severe Eosinophilic Asthma

The FDA has recently approved AstraZeneca’s Fasenra (benralizumab) as an add-on maintenance treatment for severe eosinophilic phenotype asthma in individuals ages 12 and older. Severe eosinophilic asthma is a type of asthma characterized by an increased number of eosinophils in the blood, lung tissue, and sputum (mucus coughed up from the respiratory system). Eosinophils are white blood cells that are present in healthy immune systems. These blood cells aid in combatting parasites and infections. Elevated levels of these cells, like in severe eosinophilic asthma, can cause abnormal functioning of the immune system, leading to airway inflammation, impaired lung functioning, increased risk of exacerbations, increased asthma severity and symptoms, and airway hyper-responsiveness. Severe eosinophilic asthma can cause swelling in the entire respiratory system and is most commonly diagnosed in adults.1,2

Fasenra is a monoclonal antibody that targets a receptor called the IL-5 alpha receptor on eosinophils. This action then targets the eosinophil for destruction by the body’s natural killer cells. This mechanism begins quickly, with an onset of action occurring within the first 24 hours of receiving the medication.

The safety and efficacy of Fasenra was tested in the WINDWARD trial program. Six individual phase III clinical trials made up the WINDWARD program. These included the SIROCCO, CALIMA, ZONDA, BISE, BORA, and GREGALE trials. Specifically, the SIROCCO and CALIMA trials contributed greatly to the FDA’s approval of the medication. Over 2,500 exacerbation-prone adults and adolescents over the age of 12 participated in these randomized, parallel-group, placebo-controlled, double-blind studies. Within these trials, individuals received either a fixed 30 mg dose of Fasenra every four weeks, a fixed 30 mg dose of Fasenra every four weeks for the first 3 doses, and then a 30 mg dose every eight weeks after, or placebo. The Fasenra and placebo were administered subcutaneously (as an injection under the skin) for up to 56 weeks total, and were given in addition to the standard of care for severe eosinophilic asthma.

The results of these trials indicated that for eight-week dosing regimens, individuals taking Fasenra experienced a 51% reduction in annual asthma exacerbation rates, as well as a significant improvement in lung function as measured by FEV1 (forced expiratory volume in one second) when compared to their placebo-treated counterparts. Additionally, those on Fasenra experienced a 75% median reduction in daily oral corticosteroid use (OCS) when compared to those given placebo. Further, complete discontinuation of OCS was found in 52% of eligible individuals. Many of these notable differences were noted as early as four weeks after the first dose of Fasenra was given.

Additionally, the side effects, or adverse event profile, of Fasenra was considered to be similar to that of the placebo. The side-effects that were experienced 3% of the time or higher were headache, hypersensitivity (allergic) reactions, sore throat, and fever. Fasenra is not indicated for use in other eosinophilic conditions or acute bronchospasm. Fasenra was developed in part by AstraZeneca’s global biologics research and development arm, MedImmune.2

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