GlaxoSmithKline plc (LSE/NYSE: GSK) today announced the start of a phase III programme to evaluate the efficacy and safety of mepolizumab as an adjunctive therapy for adults who have severe chronic obstructive pulmonary disease (COPD). The programme will enrol approximately 1500 patients who are at high risk of COPD exacerbations despite the use of standard background therapy.

Examination of COPD patient phenotypes has shown that an eosinophil (a type of white blood cell) predominant phenotype exists that is associated with an increased risk of exacerbations. Mepolizumab is an investigational fully humanised IgG₁ monoclonal antibody specific for interleukin-5 (IL-5). Mepolizumab prevents IL-5 from binding to its receptor on the surface of eosinophils. It is understood that inhibiting IL-5 binding reduces blood, tissue and sputum eosinophil levels.

The phase III programme consists of two pivotal studies (117113 and 117106) that together will integrate dose-ranging and long-term efficacy and safety evaluations. Each study uses a 52-week multi-centre, randomised, placebo controlled, double-blind, parallel group design. The primary endpoint in both is the frequency of moderate / severe exacerbations.

Study 117113, will randomise patients to either mepolizumab 100mg subcutaneous (SC), mepolizumab 300mg SC or placebo, administered every four weeks. All patients will be required to have a blood eosinophil count above a pre-specified threshold to be eligible for this study. Study 117106 will randomise patients to mepolizumab 100mg SC or placebo administered every four weeks. Patients in both studies will continue on baseline standard of care COPD medications throughout the entire duration of the study.

“An important goal of COPD therapy is the prevention and reduction of future exacerbations and subsequent deterioration in patients’ health,” explained Dave Allen, Head, Respiratory Therapy Area Unit, RD. “The initiation of this study programme is an important milestone in our work to provide a targeted treatment for patients who still have exacerbations despite being on standard background therapy.”

Mepolizumab is in development for COPD, severe eosinophilic asthma and Eosinophilic Granulomatosis with Polyangiitis (EGPA). Mepolizumab is not approved anywhere in the world.

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Cautionary statement regarding forward-looking statements GSK cautions investors that any forward-looking statements or projections made by GSK, including those made in this announcement, are subject to risks and uncertainties that may cause actual results to differ materially from those projected. Such factors include, but are not limited to, those described under Item 3.D 'Risk factors' in the company's Annual Report on Form 20-F for 2013.