Tiotropium Respimat® Add-On to Inhaled Corticosteroids Improves Lung Function in Patients with Symptomatic Mild Asthma: Results from A Phase III Trial

Background Despite currently available therapies and detailed guidelines, many people with mild asthma remain symptomatic; it is important to establish the efficacy and safety of new treatments in this group. Methods A Phase III, randomised, double-blind, parallel-group trial (GraziaTinA-asthma®; NCT01316380) evaluated the efficacy and safety of once-daily tiotropium 5 µg or 2.5 µg versus placebo (all delivered via the Respimat® SoftMist™ inhaler) for 12 weeks in patients with symptomatic asthma on low-dose inhaled corticosteroids (200–400 µg budesonide or equivalent). The primary end point was peak forced expiratory volume in 1 second (FEV1) within 3 h of dosing (0–3h) response (change from baseline) at 12 weeks. Secondary end points were trough FEV1, FEV1 area under the curve (AUC)(0–3h) and peak expiratory flow responses (measured with the AM2+® device), and seven-question Asthma Control Questionnaire (ACQ-7) score. Results Of 464 treated patients, 155 received tiotropium Respimat® 5 µg, 154 received tiotropium Respimat® 2.5 µg and 155 received placebo Respimat®. Both tiotropium Respimat® doses were superior to placebo Respimat® in peak FEV1(0–3h) response (adjusted mean difference: 5 µg, 128 mL; 2.5 µg, 159 mL; both p < 0.001) and trough FEV1 response (adjusted mean difference: 5 µg, 122 mL, p = 0.001; 2.5 µg, 110 mL, p = 0.003). FEV1 AUC(0–3h) response at each visit, versus placebo Respimat®, significantly favoured tiotropium Respimat® 5 µg (p = 0.009 to p < 0.001) and 2.5 µg (all p < 0.001, except Day 1). Adjusted mean morning and evening peak expiratory flow responses, versus placebo Respimat®, each week, all favoured tiotropium Respimat® 5 µg (all p < 0.001) and 2.5 µg (all p < 0.003). Adjusted mean ACQ-7 score was similar across all arms (tiotropium Respimat® 5 µg, 1.391; tiotropium Respimat® 2.5 µg, 1.438; placebo Respimat®, 1.377). Adverse events were predominantly mild or moderate and were balanced between treatment groups. Conclusion Tiotropium Respimat® was effective and well tolerated in patients with symptomatic mild asthma despite low-dose inhaled corticosteroid treatment.