Boehringer Ingelheim announced the initiation of a Phase 2a clinical trial for BI 765423, a novel monoclonal antibody targeting interleukin-11 (IL-11), in patients with idiopathic pulmonary fibrosis (IPF). The study is designed to assess whether BI 765423 can improve lung function by directly inhibiting IL-11, a profibrotic cytokine implicated in lung scarring and tissue remodeling.

IPF is a progressive, life-shortening interstitial lung disease affecting over three million people worldwide, marked by relentless decline in lung function and median survival shorter than many common cancers. Current therapies, including Boehringer Ingelheim’s Jascayd (nerandomilast), can slow disease progression but do not fully halt fibrosis or restore lung integrity, highlighting a substantial unmet need for next-generation treatments.

BI 765423 is designed to bind IL-11 and block its interaction with the receptor, thereby interrupting downstream signaling that drives fibrotic processes. Preclinical evidence suggests IL-11 blockade can not only slow fibrosis but also restore tissue barrier function and improve lung mechanics. In Phase I studies in healthy volunteers, BI 765423 demonstrated a favorable safety and tolerability profile. The Phase IIa trial will be the first to evaluate efficacy in IPF patients.

The asset was in-licensed from Singapore-based Enleofen in 2020, with intellectual property contributions from Singapore Health Services and the National University of Singapore. Boehringer Ingelheim’s push into IL-11 inhibition underscores broader industry interest in targeting novel profibrotic pathways beyond conventional approaches.

Boehringer is looking to build on the respective October and December 2025 US FDA approvals for Jascayd in Idiopathic Pulmonary Fibrosis (IPF) and Progressive Pulmonary Fibrosis (PPF), marking the first new IPF therapy in a decade, and reflects BI’s ongoing investment in pulmonary fibrosis R&D.

Research context

IL-11 is a member of the IL-6 cytokine family and was initially characterized for its role in hematopoiesis, particularly in stimulating platelet production (thrombopoiesis) and as a cytoprotective agent in chemotherapy-induced thrombocytopenia – an indication for which Wyeth Pharma’s oprelvekin (recombinant human IL-11) was approved in 1997. Recent advances have shifted the perception of IL-11 from a primarily hematopoietic and cytoprotective cytokine to a central mediator of pathological fibrosis, tissue remodeling, and age-related disease processes.

Current development efforts in the field are focused on IL-11-targeted monoclonal antibodies, with competing molecules including: Mabwell/Calico Life Sciences’ 9MW3811, which completed Phase 1 studies in healthy volunteers in Australia and China and is set for Phase 2 study in pathological scarring; and Lassen Therapeutics’ LASN01, an IL-11Rα-targeted mAb in Phase 1 trials for fibro-inflammatory diseases, including IPF and thyroid eye disease. Other agents at the preclinical stages include long-acting IL-11 antagonists for renal fibrosis and engineered IL-11 analogues.