ASP4058, a Novel Agonist for Sphingosine 1-Phosphate Receptors 1 and 5, Ameliorates Rodent Experimental Autoimmune Encephalomyelitis with a Favorable Safety Profile

Sphingosine-1-phosphate (S1P) is a biologically active sphingolipid that acts through the members of a family of five G protein-coupled receptors (S1P 1 –S1P 5 ). S1P 1 is a major regulator of lymphocyte trafficking, and fingolimod, whose active metabolite fingolimod phosphate acts as a nonselective S1P receptor agonist, exerts its immunomodulatory effect, at least in part, by regulating the lymphocyte trafficking by inducing down regulation of lymphocyte S1P 1 . Here, we detail the pharmacological profile of 5-{5-[3-(trifluoromethyl)-4-{[(2 S )-1,1,1-trifluoropropan-2-yl]oxy}phenyl]-1,2,4-oxadiazol-3-yl}-1 H -benzimidazole (ASP4058), a novel next-generation S1P receptor agonist selective for S1P 1 and S1P 5 . ASP4058 preferentially activates S1P 1 and S1P 5 compared with S1P 2, 3, 4 in GTPγS binding assays in vitro . Oral administration of ASP4058 reduced the number of peripheral lymphocytes and inhibited the development of experimental autoimmune encephalomyelitis (EAE) in Lewis rats. Further, ASP4058 prevented relapse of disease in a mouse model of relapsing-remitting EAE. Although these immunomodulatory effects were comparable to those of fingolimod, ASP4058 showed a wider safety margin than fingolimod for bradycardia and bronchoconstriction in rodents. These observations suggest that ASP4058 represents a new therapeutic option for treating multiple sclerosis that is safer than nonselective S1P receptor agonists such as fingolimod.