– AKP-11 is a sphingosine-1-phosphate receptor 1 (S1P1) agonist with an EC50 of 0.047 μM for [35S]GTPγS binding to CHO-K1 cell membranes expressing human S1P1. It reduces S1P1 surface expression and enhances Akt and ERK phosphorylation in CHO cells with S1P1-HA at a 100 nM concentration. At doses of 1.3 and 3 mg/kg, AKP-11 lowers IFN-γ and IL-17 protein levels in the spinal cord and mitigates disease severity in a rat experimental autoimmune encephalomyelitis (EAE) model. Additionally, it decreases peripheral total lymphocyte and specific T cell subsets (CD4+, CD8+, and CD26L+ T cells) counts in both EAE rats and healthy controls at a 1.3 mg/kg dosage.