Synergistic Bronchorelaxant Effects of Ensifentrine in Combination With Inhaled Therapies in a Human Ex Vivo Model of COPD

Rationale Chronic Obstructive Pulmonary Disease (COPD) is a progressive lung condition characterized by persistent airflow limitation and inflammation. Current treatments often involve combinations of long-acting muscarinic antagonists (LAMAs), long-acting beta-agonists (LABAs), and inhaled corticosteroids (ICS). Ensifentrine, a dual phosphodiesterase (PDE) 3/4 inhibitor, has demonstrated potential in providing both bronchodilation and anti-inflammatory benefits. This study aimed to explore the synergistic effects of ensifentrine when combined with standard inhaled COPD therapies (LAMA, LABA, ICS/LABA, LABA/LAMA, ICS/LABA/LAMA) in an ex vivo human model, and to determine whether airway epithelium plays a role in these interactions. Methods Human sub-segmental bronchi were isolated from COPD donors and challenged with lipopolysaccharide (LPS) 300 ng/mL for 2 hours to induce inflammation and increased contractility. Relaxation responses were measured in bronchi with both intact and denuded epithelium that had been pre-contracted with carbachol at EC70. Ensifentrine was tested alone and in combination with the LABA formoterol fumarate (FF), the LAMA glycopyrronium bromide (GB), and the ICS beclomethasone dipropionate (BDP), at concentrations consistent with approved fixed-dose combinations for COPD (ICS/LABA, LABA/LAMA, ICS/LABA/LAMA). The interactions were assessed using the Bliss-Loewe Uncertainty Range (BLUR) model, an advanced method for evaluating drug-drug synergy, at both EC30 and EC50 concentrations. Results Ensifentrine demonstrated significant bronchorelaxation in LPS-challenged bronchi, with an Emax of 81.72±6.55% and a pEC50 of 4.83±0.12. No significant difference was observed in epithelium-denuded airways, where Emax was 82.21±5.79% and pEC50 of 4.88±0.22, suggesting the epithelium does not significantly modulate the response to ensifentrine. Synergistic effects were observed at low concentrations (EC30) when ensifentrine was combined with GB (+17.50±3.08%), BDP/FF (+18.65±6.26%), FF/GB (+19.28±3.77%), BDP/FF/GB (+19.39±3.06%). At higher concentrations (EC50), the strongest synergy was noted in combinations with FF/GB (+16.21±2.97%) and BDP/FF/GB (+14.63±1.88%). In contrast, combinations with FF alone showed additive, but not synergistic, effects. Conclusions Ensifentrine provides effective bronchorelaxation in human COPD airways challenged with LPS, with no significant contribution from the airway epithelium. The study highlights the potential of ensifentrine to synergistically enhance the efficacy of commonly used inhaled therapies, particularly in combination with LAMA, LABA/LAMA, ICS/LABA and ICS/LABA/LAMA. These findings suggest that ensifentrine could be a valuable adjunct in COPD management, reinforcing clinical evidence from recent Phase III ENHANCE trials [1]. This study was funded by Verona Pharma plc. [1] Anzueto et al., Am J Respir Crit Care Med, 2023, 208(4):406-416.