The Selective Sphingosine 1-Phosphate Receptor Modulator Etrasimod Regulates Lymphocyte Trafficking and Alleviates Experimental Colitis.

Lymphocyte trafficking out of secondary lymphoid organs is regulated by concentration gradient-dependent interactions between the membrane-derived lysophospholipid signaling molecule sphingosine 1-phosphate (S1P) and the G-protein-coupled receptor, S1P1 Etrasimod is a novel, next-generation, small-molecule, oral S1P receptor modulator in clinical development for the treatment of immune-mediated inflammatory disorders, including ulcerative colitis. In preclinical pharmacology studies, etrasimod was a full agonist of recombinant human (6.1 nM EC50), mouse (3.65 nM EC50), dog (4.19 nM EC50), and monkey (8.7 nM EC50) S1P1 receptors, and a partial agonist of human S1P4 (147 nM EC50) and S1P5 (24.4 nM EC50), with relative efficacies of 63% and 73% of S1P response, respectively; whereas neither agonist nor antagonist activity was observed for human S1P2 or S1P3 A dose-dependent relationship was observed for etrasimod plasma concentration and lymphocyte count in mice, and chronic treatment with etrasimod resulted in attenuation of inflammation in a CD4+CD45RBhigh T-cell transfer mouse model of colitis.