Background: Good symptom control is one of the goals of asthma therapy. Clinical trials have shown significant therapeutic benefits of extrafine formulation single-inhaler triple therapy (efSITT) consisting of beclometasone dipropionate/formoterol fumarate/glycopyrronium in the treatment of patients with asthma. Real-world data on the impact of efSITT on asthma control is lacking. Aims and objectives: The TriMaximize study aims to provide evidence for the therapy pathways, asthma control and health-related outcomes of patients with moderate-to-severe asthma prescribed efSITT in real-world practice. Methods: This is a multicenter, multinational, prospective, observational study investigating the impact of efSITT in patients with moderate-to-severe asthma over a period of 1?3 years. We present an interim analysis of the changes in asthma control in the first 328 patients from Germany, United Kingdom, Austria and Denmark after three months of treatment with efSITT. Changes in asthma control were measured using the Asthma Control Test (ACT). Results: The majority (76%) of patients were on prior ICS/LABA treatment, and 24% on prior ICS/LABA/LAMA. Mean ACT score at baseline was 14.4 points. After three months of treatment with efSITT, mean change from baseline in ACT score was 3.3 points in the overall population, and 3.7 points in patients on prior ICS/LABA (both p<0.0001). Both results exceeded the MCID of 3 points. Conclusions: Our data show a significant improvement in asthma control in patients with moderate-to-severe asthma after three months of treatment with efSITT following a switch from ICS/LABA or ICS/LABA/LAMA.