The In Vitro Pharmacology of GS-5759, A Novel Bifunctional Phosphodiesterase 4 Inhibitor and Long Acting β2-Adrenoceptor Agonist

Inhaled long-acting β2-adrenoceptor agonists (LABA) that act as bronchodilators and the oral anti-inflammatory phosphodiesterase 4 (PDE4) inhibitor roflumilast are both approved therapies for chronic obstructive pulmonary disease (COPD). Here we describe the activity of a novel, inhaled, bifunctional, small molecule (R)-6-[(3-{[4-(5-{[2-hydroxy-2-(8-hydroxy-2-oxo-1,2-dihydroquinolin-5-yl)ethyl]amino}pent-1-yn-1-yl)phenyl]carbamoyl}phenyl)sulfonyl]-4-[(3-methoxyphenyl)amino]-8-methylquinoline-3-carboxamide (GS-5759), which has specific β2 agonist and PDE4 inhibitory activity. GS-5759 demonstrated potent and full agonist activity at β2 adrenoceptors (EC50 = 8 ± 4 nM) and is a potent inhibitor of the PDE4 enzyme (IC50 = 5 ± 3 nM). In cell assays, GS-5759 inhibited lipopolysaccharide (LPS)-induced tumor necrosis factor α (TNFα) production in human peripheral mononuclear cells (PBMC) with an IC50 = 0.3 nM [confidence interval (CI) 0.1–0.6] and in human neutrophils formyl-methionyl-leucyl-phenylalanine (fMLP)-induced super oxide anion production with an IC50 = 3 nM (CI 0.8–8). The addition of the β2 antagonist ICI 118551 shifted the IC50 in these cell assays to 4 and 38 nM, respectively, demonstrating the contribution of both β2 agonist and PDE4 inhibitory activity to GS-5759. GS-5759 was also a potent inhibitor of profibrotic and proinflammatory mediator release from human lung fibroblasts. GS-5759 relaxed guinea pig airway smooth muscle strips precontracted with carbachol in a concentration-dependent manner with an EC50 = 0.5 µM (CI 0.2–2) and had slow dissociation kinetics with an Off T1/2 > 720 minutes at an EC80 concentration of 3 µM. GS-5759 is a novel bifunctional molecule with both potent β2 agonist and PDE4 inhibitor activity that could provide inhaled bronchodilator and anti-inflammatory therapy for COPD.