Mepolizumab


Mepolizumab, sold under the brand name Nucala, is a humanized monoclonal antibody used for the treatment of severe eosinophilic asthma. It recognizes and blocks interleukin-5, a signalling protein of the immune system.

Medical uses

Mepolizumab is approved by the U.S. Food and Drug Administration for the maintenance treatment of severe asthma in patients aged 6 years or older and with an eosinophilic phenotype in combination with other medicines used to treat asthma.
In Europe it is approved as an add-on treatment for severe refractory eosinophilic asthma in adult patients.
In studies, mepolizumab cut the necessity for hospitalisation due to asthma exacerbations in half, as compared to placebo.
In December 2017, the FDA expanded mepolizumab's indication to treat adults with eosinophilic granulomatosis with polyangiitis, which is a rare autoimmune condition that can cause vasculitis.

Side effects

Common side effects in clinical trials included headache, reactions at the site of injection, infections of the urinary tract and the lower respiratory tract, eczema and muscle spasms.

Overdose

Single doses of 15 times the usual therapeutic dose have been tolerated in studies without significant side effects.

Interactions

No interaction studies have been conducted. As with other monoclonal antibodies, the interaction potential is considered to be low.

Pharmacology

Mechanism of action

Mepolizumab binds to IL-5 and prevents it from binding to its receptor, more specifically the interleukin 5 receptor alpha subunit, on the surface of eosinophil white blood cells. While eosinophils play a role in inflammation associated with asthma, the exact mechanism of mepolizumab is unknown.

Pharmacokinetics

After subcutaneous injection, mepolizumab has an estimated bioavailability of 80% and reaches highest blood plasma concentrations after four to eight days. Like other antibodies, it is degraded by proteolytic enzymes. Its biological half-life is 20 days on average, ranging from 16 to 22 days in different individuals.

Chemistry

The substance is an IgG1 kappa monoclonal antibody, the two heavy chains consisting of 449 amino acids each, and the two light chains consisting of 220 amino acids each. The protein part has a molar mass of about 146 kDa, and the sugar part of 3 kDa.

History

Phase III clinical trials in severe eosinophilic asthma were completed in 2014. The FDA approved it in November 2015. The European Commission granted a marketing authorisation valid throughout the European Union on 2 December 2015.

Research

Mepolizumab has been investigated or is under investigation for the treatment of atopic dermatitis, hypereosinophilic syndrome, eosinophilic esophagitis, nasal polyposis, eosinophilic granulomatosis with polyangiitis, and chronic obstructive pulmonary disease.