Ponesimod -d 7 (ACT-128800-d 7 ) is the deuterium-labeled Ponesimod. Ponesimod -d 7 (ACT-128800) is a potent, selective and orally active agonist of S1P 1 , with an IC 50 of 6 nM in a radioligand binding assay. Ponesimod -d 7 activates S1P 1 -mediated signal transduction with high potency ( EC 50 =5.7 nM). Ponesimod -d 7 can protect against lymphocyte-mediated tissue inflammation.