Phase 2 study design and analysis approach for BBT-877: an autotaxin inhibitor targeting idiopathic pulmonary fibrosis.

Introduction: Proof-of-concept (POC) studies are vital in determining the feasibility of further drug development, primarily by assessing preliminary efficacy signals with credible endpoints. However, traditional POC studies in idiopathic pulmonary fibrosis (IPF) can suffer from low credibility due to small sample sizes and short durations, leading to non-replicable results in larger phase III trials. To address this, we are conducting a 24-week POC study with 120 patients with IPF, using a statistically supported sample size and incorporating exploratory CT-based imaging biomarkers, to support decision-making in the case of non-significant primary endpoint results. This approach aims to provide data to enable a robust decision-making process for advancing clinical development of BBT-877.

Methods and analysis: In this phase II, double-blind, placebo-controlled study, approximately 120 patients with IPF will be randomised in a 1:1 ratio to receive placebo or 200 mg of BBT-877 two times per day over 24 weeks, with stratification according to background use of an antifibrotic treatment (pirfenidone background therapy, nintedanib background therapy or no background therapy). The primary endpoint is absolute change in forced vital capacity (FVC) (mL) from baseline to week 24. Key secondary endpoints include change from baseline to week 24 in %-predicted FVC, diffusing capacity of the lung for carbon monoxide, 6 min walk test, patient-reported outcomes, pharmacokinetics and safety, and tolerability. Key exploratory endpoints include eLung-based CT evaluation and biomarker-based assessment of pharmacodynamics.

Ethics and dissemination: This study is being conducted following the Declaration of Helsinki principles, Good Clinical Practice guidance, applicable local regulations and local ethics committees. An independent data monitoring committee unblinded to individual subject treatment allocation will evaluate safety and efficacy data on a regular basis throughout the study. The results of this study will be presented at scientific conferences and peer-review publications.

Trial registration number: NCT05483907.