Potential of phosphodiesterase 4B inhibitors in the treatment of interstitial lung disease associated with autoimmune diseases

Patients with autoimmune disease-related interstitial lung disease may develop pulmonary fibrosis, which may become progressive. Progressive pulmonary fibrosis (PPF) is associated with poor outcomes. Antifibrotic therapies have shown efficacy as treatments for PPF in patients with autoimmune diseases, but new treatments are needed to slow or halt disease progression. Phosphodiesterases (PDEs) are enzymes that mediate the hydrolysis of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Pre-clinical data suggest that preferential inhibition of PDE4B has the potential to slow the progression of pulmonary fibrosis by inhibiting inflammatory and fibrotic pathways, with a lower risk of gastrointestinal adverse events than associated with pan-PDE4 inhibitors. Nerandomilast (BI 1015550) is a preferential PDE4 inhibitor that has demonstrated anti-inflammatory and antifibrotic effects in pre-clinical studies. In a phase II trial in patients with idiopathic pulmonary fibrosis, nerandomilast (given alone or on top of background antifibrotic therapy) prevented a decrease in lung function over 12 weeks with an acceptable safety and tolerability profile. The phase III FIBRONEER-ILD trial is evaluating the efficacy and safety of nerandomilast, given alone or on top of nintedanib, in patients with PPF, including PPF associated with autoimmune diseases. In this article, we review the potential of PDE4B inhibition in the treatment of ILD associated with autoimmune diseases, including the pre-clinical and early clinical data available to date.