An Oral Sphingosine 1-Phosphate Receptor 1 (S1P1) Antagonist Prodrug with Efficacy in Vivo: Discovery, Synthesis, and Evaluation

A prodrug approach to optimize the oral exposure :of a series of sphingosine 1-phosphate receptor 1 (S1P(1)) antagonists for chronic efficacy studies led to the discovery of dimethylphenylsulfonylamino)-3,5-dimethylbiphenyl-4-carbonyl]-methylamino}-4-dimethylaminobutyric acid methyl ester 14. Methyl ester prodrug 14 is hydrolyzed in vivo to the corresponding carboxylic, acid 15, a potent and selective S1P(1) antagonist.: Oral; administration of the prodrug 14 induces sustained peripheral blood lymphocyte reduction.. in rats. In a rat: cardiac transplantation model coadministration of a nonefficacious dose of prodrung 14 with a nonefficacious dose of sotrastaurin (19), a protein kinase C inhibitor, or everolimus mTOR inhibitor, effectively prolonged the survival time of rat cardiac allografts. This demonstrates that clinically useful immunomodulation mediated by the S1P(1) receptor can be achieved with an S1P(1) antagonist generated in vivo after oral administration of its prodrug.