On May 20 at the American Thoracic Society (ATS) international conference, during a poster session, Boehringer Ingelheim (BI) presented positive results based on final pooled data from the Phase II studies AIRLEAF (NCT05238675) and CLAIRLEAF (NCT05846230) for its asset verducatib (BI 1291583) in non-cystic fibrosis bronchiectasis (NCFB). Verducatib, a dipeptidyl peptidase 1 (DPP1) / cathepsin C inhibitor, demonstrated its ability to suppress neutrophilic airway inflammation, reduce the risk of pulmonary exacerbations (PEx), and improve lung infection in bronchiectasis patients, and is currently being evaluated in the Phase III AIRTIVITY (NCT06872892) study. The results provide validation of the DPP1 inhibition in bronchiectasis and reinforce the drug class’s position in this disease space and signal an opportunity for verducatib to compete against Insmed’s Brinsupri (brensocatib), the first-in-class and first-to-market DPP1 inhibitor for NCFB.
The AIRLEAF study was a multinational, randomised, double-blind, placebo-controlled, parallel-group, dose-finding study that enrolled 322 adults with computed tomography (CT)-confirmed bronchiectasis. Participants received once-daily doses of verducatib (1.0mg / 2.5mg / 5.0mg) or placebo. 26 participants in the placebo group in the AIRLEAF study either discontinued early or did not enter the rollover study. Once the participants entered the CLAIRLEAF study (n=296), those on active treatment arms remained on the same dose while those who received placebo were blindly randomised to one of three doses of verducatib (1.0mg dose: 80 participants, 2.5mg: 81 participants, 5.0mg: 135 participants). In the absence of a placebo in the CLAIRLEAF study, verducatib 2.5mg and 5.0mg were compared against the verducatib 1.0mg dose.
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Results demonstrated that the 2.5mg dose verducatib was associated with a 21% lower risk of first PEx compared to the 1.0mg dose at week 156, and the 5.0mg dose of verducatib was associated with a 7% lower risk of first PEx compared to the 1.0mg dose for the same time. Annualised rate of PExs was also observed to be better in the 2.5mg dose group with a 32% reduction compared with 1.0mg dose at week 156; in the 5.0mg dose, a 3% reduction in rate of annualised PExes was observed compared to the 1.0mg dose at week 56. Results presented at ATS 2026 were consistent with the results of the pre-specified, exploratory analysis up to week 104 using interim pooled data from the same Phase II trials, the latter set of results having been reported at the 2025 European Respiratory Society (ERS) Congress. Based on the results from the Phase II pooled data, 2.5mg verducatib is currently being investigated in the Phase III AIRTIVITY trial.
DPP1 inhibitors marked a significant achievement when Brinsupri received FDA approval in August 2025 as the first-to-market therapy for NCFB. As a disease-modifying treatment, Brinsupri has largely set a precedent for other DPP1 inhibitors that are in pipeline development, including verducatib. Brinsupri’s approval label mandates the therapy to be taken daily, and as an extension of that dosing regimen, it is anticipated that patients will be on these therapies on a long-term basis. Prolonged reliance on these therapies necessitates long-term efficacy and safety studies, such as the one presented on verducatib, and this data is expected to play a significant role in bolstering the asset’s profile as it progresses to later stages of clinical development.
