Efficacy of peripherally targeted inhaled rhDNase for persistent obstructive asthma in childhood

INTERVENTION: Nebulization with rhDNase or placebo once daily (each participant is treated for two weeks with rhDNase and for 2 weeks with placebo) CONDITION: Obstructive pulmonary function, asthma ; Respiratory ; Obstructive pulmonary disease, asthma PRIMARY OUTCOME: Primary endpoint will be the change in FEF75 as a result of treatment. FEF75 is the most suitable endpoint since it is sensitive to peripheral airways obstruction. SECONDARY OUTCOME: Secondary endpoints will include: ; 1. Lung clearance index (LCI) measurements as assessed by multiple breath washout; 2. Cumulative symptom diary scores evaluating asthma symptoms in the second week of intervention (e.g. shortness of breath, cough, exercise intolerance, bronchodilator use etc.);; 3. Fraction of exhaled nitric oxide (FENO); 4. Other values obtained in the flow volume curve: FEV1, FVC, peak expiratory flow (PEF) INCLUSION CRITERIA: 1. Aged 6 ‐ 18 years 2. Asthma diagnosed according to Global Initiative For Asthma (GINA) guidelines 3. Attending the outpatient clinic for at least one year 4.Treatment with at least 400 mg/day inhaled budesonide or equivalent (dose constant for at least 6 months) and bronchodilators as needed or daily 5. Clinically stable asthma while using a constant dose of Inhaled Corticosteroid (ICS) for at least three months 6. Ability to perform lung function tests (assessed by trained lung function technician) 7. Persistent peripheral airways obstruction as assessed by pulmonary function testing, defined as: dissociation between forced vital capacity (FVC) and FEF75 values: FEF75 at least 20% (absolute % predicted) lower than FVC (FEF = Forced Expiratory Flow rate) 8. FVC within normal limits (for this study defined as FVC >80% predicted)