Masahiro Iwata

ASP3258, an orally active potent phosphodiesterase 4 inhibitor with low emetic activity.

We investigated the pharmacology of a novel phosphodiesterase (PDE) 4 inhibitor, ASP3258 (3-[4-(3-chlorophenyl)-1-ethyl-7-methyl-2-oxo-1,2-dihydro-1,8-naphthyridin-3-yl] propanoic acid), comparing its potency with that of the most advanced PDE4 inhibitors, roflumilast and cilomilast. PDE4 inhibition by ASP3258 (IC(50)=0.28nM) was as potent as that achieved with roflumilast. ASP3258 inhibited lipopolysaccharide-induced tumor necrosis factor (TNF)-α production in rat whole blood cells (IC(50)=8.8 nM) and rat alveolar macrophages (IC(50)=2.6 nM). Orally administered ASP3258, roflumilast, and cilomilast dose-dependently inhibited production of interleukin-4, TNF-α, and cysteinyl leukotrienes, as well as leukocyte infiltration in bronchoalveolar lavage fluid from the airways of ovalbumin-sensitized Brown Norway rats, and these compounds showed almost complete inhibition at doses of 3, 3, and 30 mg/kg, respectively. PDE4 inhibitors induce emesis by mimicking the pharmacological action of α(2)-adrenoceptor antagonist. However, orally administered roflumilast (3mg/kg) and cilomilast (10mg/kg), but not ASP3258 (3mg/kg), inhibited α(2)-adrenoceptor agonist-induced anesthesia in rats and induced emesis in ferrets. Although ASP3258 (3mg/kg) inhibited airway inflammation completely, it had no emetic activity. As such, this compound may be useful in treating airway inflammatory diseases such as asthma and COPD.

Identification of 4-benzylamino-2-[(4-morpholin-4-ylphenyl)amino]pyrimidine-5-carboxamide derivatives as potent and orally bioavailable STAT6 inhibitors

Signal transducers and activators of transcription 6 (STAT6) is a key regulator of the type 2 helper T (Th2) cell immune response and a potential therapeutic target for allergic diseases such as asthma and atopic diseases. To search for potent and orally bioavailable STAT6 inhibitors, we synthesized a series of 4-benzylaminopyrimidine-5-carboxamide derivatives and evaluated their STAT6 inhibitory activities. Among these compounds, 2-[(4-morpholin-4-ylphenyl)amino]-4-[(2,3,6-trifluorobenzyl)amino]pyrimidine-5-carboxamide (25y, YM-341619, AS1617612) showed potent STAT6 inhibition with an IC(50) of 0.70nM, and also inhibited Th2 differentiation in mouse spleen T cells induced by interleukin (IL)-4 with an IC(50) of 0.28 nM without affecting type 1 helper T (Th1) cell differentiation induced by IL-12. In addition, compound 25y showed an oral bioavailability of 25% in mouse.

Anti-neutrophilic inflammatory activity of ASP3258, a novel phosphodiesterase type 4 inhibitor.

Neutrophil-dominant pulmonary inflammation is an important feature of chronic obstructive pulmonary disease (COPD). Here, we evaluated the in vitro and in vivo anti-neutrophilic inflammatory activities of ASP3258, a novel, orally active, and selective phosphodiesterase (PDE) 4 inhibitor with anti-inflammatory potency comparable to that of second-generation compound roflumilast but with lower emetic activity in vivo. In in vitro experiments using human peripheral blood neutrophils, PDE4 inhibitors ASP3258, cilomilast, and roflumilast inhibited fMLP-induced superoxide production in a concentration-dependent manner with IC50 values of 5.0, 96, and 4.7 nM, respectively. ASP3258, cilomilast, and roflumilast also attenuated fMLP-induced neutrophil chemotaxis in a concentration-dependent manner with IC30 values of 18, 270, and 9.7 nM, respectively. In contrast, the glucocorticoid prednisolone inhibited neither superoxide production nor chemotaxis up to 1 μM. In a rat model of lipopolysaccharide (LPS)-induced lung inflammation, orally administered ASP3258, cilomilast, roflumilast, and prednisolone (at 10 or 30 mg/kg) dose-dependently attenuated pulmonary accumulation of neutrophils. The inhibitory effect of ASP3258 was more potent than cilomilast and almost the same as roflumilast and prednisolone. Treatment with ASP3258 inhibited the elevation of TNF-α in the bronchoalveolar lavage fluid following LPS instillation. Histological examination revealed significant inhibition of neutrophil and macrophage infiltration into alveoli by ASP3258. Overall, these findings suggest that ASP3258 has therapeutic potential for treating neutrophilic inflammation such as COPD, partly through direct inhibition of neutrophil activation as well as possibly through inhibition of the TNF-α-mediated pathway.

Disease-modifying effect of ASP3258, a novel phosphodiesterase type 4 inhibitor, on subchronic cigarette smoke exposure-induced lung injury in guinea pigs.

ASP3258 is a novel, orally active, selective phosphodiesterase (PDE) 4 inhibitor which has an improved therapeutic window over second generation compounds such as roflumilast and cilomilast. Here, we investigated the effect of ASP3258 on cigarette smoke exposure-induced lung injury in guinea pigs, a well-defined model for chronic obstructive pulmonary disease (COPD). COPD-like lung injury was induced by repeated cigarette smoke exposure (10 cigarettes/day, 5 days/week, for 4 weeks). Orally administered ASP3258 (0.3, 1, and 3mg/kg) dose-dependently suppressed pulmonary accumulation of mononuclear cells and neutrophils, and the inhibitory effect of ASP3258 (1mg/kg) was almost the same as that of roflumilast (1mg/kg). In contrast, a glucocorticoid prednisolone (10mg/kg, p.o.) did not show any effect. Histological examination revealed that ASP3258 treatment significantly inhibited infiltration of neutrophils and macrophages into either or both alveolar or peribronchiolar areas, as well as hyperplastic and squamous metaplastic changes of epithelium in the bronchi. Decreasing trends in histological scores for accumulation of lymphocytes in the alveoli and alveolar wall thickening were also observed in ASP3258-treated animals. Further, ASP3258 attenuated augmentation of matrix metalloproteinase-9 activity in the bronchoalveolar lavage fluid. These findings suggest that ASP3258 has therapeutic potential for treating COPD not only through inhibition of pulmonary cellular accumulation but also by preventing lung structural alterations initiated by repeated cigarette smoke exposure. To our knowledge, this is the first paper demonstrating that PDE4 inhibitors exert significant inhibitory effects on subchronic cigarette smoke exposure-induced lung injury in guinea pigs.

Therapeutic Potential of ASP3258, a Selective Phosphodiesterase 4 Inhibitor, on Chronic Eosinophilic Airway Inflammation

We investigated and compared the pharmacological effects of a PDE4 inhibitor ASP3258 (3-[4-(3-chlorophenyl)-1-ethyl-7-methyl-2-oxo-1,2-dihydro-1,8-naphthyridin-3-yl] propanoic acid), with those of roflumilast, the most clinically advanced PDE4 inhibitor known. ASP3258 inhibited human PDE4A, 4B, 4C, and 4D with respective IC50 values of 0.036, 0.050, 0.45, and 0.035 nmol/l, all approximately 3–6 times more potent than roflumilast. ASP3258 inhibited LPS-induced TNF-α production and PHA-induced IL-5 production in human whole blood cells with respective IC50 values of 110 and 100 nmol/l, both approximately 10 times less potent than roflumilast. Repeatedly administered ASP3258 and roflumilast both suppressed chronic airway eosinophilia induced by repeated exposure to ovalbumin in Brown Norway rats with respective ED50 values of 0.092 and 0.17 mg/kg. We also evaluated the toxicological profiles of ASP3258. Although PDE4 inhibitors induce emesis by mimicking the pharmacological action of an α2-adrenoceptor antagonist, repeated administration of ASP3258 (3 mg/kg) had no such inhibitory effect on rats anesthetized with α2-adrenoceptor agonist. PDE4 inhibitors are also known to induce vascular injury in rats. Although repeatedly administered ASP3258 (3 and 10 mg/kg) significantly increased plasma fibrinogen, a biomarker for toxicity, 1 mg/kg of ASP3258 did not. These results suggest that ASP3258 is an attractive PDE4 inhibitor for treating chronic eosinophilic airway inflammation due to asthma.