The purpose of this study is to assess the safety and efficacy of masitinib (6 mg/kg/day) in severe persistent asthma, uncontrolled with high dose of inhaled corticosteroid and with elevated eosinophil levels.

Masitinib is a selective tyrosine kinase inhibitor. It is known that activation of inflammatory cells, such as mast cells, and fibrous tissue remodeling are associated with c-Kit, Lyn and PDGFR kinase signaling pathways; all key targets of masitinib. This is a multicenter, double-blind, randomized, parallel-group (ascending dose titration of masitinib to 6.0 mg/kg/day and matching placebo), comparative study of oral masitinib in the treatment of patients with severe asthma, uncontrolled with high dose of inhaled corticosteroid and with elevated eosinophil levels. Eligible patients will be treated during at least 48 weeks.

Main inclusion criteria include:

• Patients with a physician diagnosis of persistent asthma for at least 12 months based on Global Initiative for Asthma (GINA) 2009 Guidelines whose asthma is partially controlled or uncontrolled on inhaled corticosteroids (ICS) / long-acting beta2-agonists (LABA) combination therapy.
• Patient with elevated eosinophil level related to asthma at baseline: ≥0.15 K/uL or patient with eosinophil level ≥0.15 K/uL related to asthma demonstrated in the year prior to screening
• Non-smoker patient for at least one year and with a prior tobacco consumption <10 packs/year

Main exclusion criteria include:

• Female patient who is pregnant or lactating
• Asthmatic patient still exposed to allergens or to triggering factors influencing asthma control
• Chronic obstructive pulmonary disease and/or other lung diseases impairing Pulmonary Function Tests
• Within 12 weeks prior to screening, patient who received oral corticosteroids for any other reason than to treat severe asthma exacerbation (patients needing long term corticosteroids intake to control basal asthma condition)
• Patient with history of acute infectious sinusitis or respiratory tract infection within 4 weeks prior to screening visit
• Patient with active lung disease other than asthma (e.g. chronic bronchitis)