In vitro assessment of the binding and functional responses of ozanimod and its plasma metabolites across human sphingosine 1-phosphate receptors

Ozanimod is approved in multiple countries for the treatment of adults with either relapsing multiple sclerosis or moderately to severely active ulcerative colitis. Ozanimod is metabolized in humans to form seven active plasma metabolites, including two major active metabolites CC112273 and CC1084037, and an inactive metabolite. Here, the binding and activity of ozanimod and its metabolites across human sphingosine 1-phosphate receptors were determined. Binding affinity was assessed in Chinese hamster ovary cell membranes expressing recombinant human sphingosine 1-phosphate receptors 1 and 5 via competitive radioligand binding using tritium-labeled ozanimod; selectivity via functional potency assessment was performed using [35S]-guanosine-5'-(γ-thio)-triphosphate binding assays. Receptor internalization was assessed in human embryonic kidney 293 cells overexpressing sphingosine 1-phosphate receptor 1-green fluorescent protein and Chinese hamster ovary cells overexpressing sphingosine 1-phosphate receptor 5-hemagglutinin via fluorescence activated cell sorting. Functional activity was assessed in primary cultures of human astrocytes via phosphorylation assays. Ozanimod and its functionally active metabolites bound to the same sites within sphingosine 1-phosphate receptors 1 and 5, with metabolites displaying the same selectivity profile as ozanimod. Agonism at sphingosine 1-phosphate receptor 1 induced receptor internalization, whereas sphingosine 1-phosphate receptor 5 did not. Ozanimod, CC112273, and CC1084037 elicited functional intracellular signaling in human astrocytes, pharmacologically characterized to be mediated by sphingosine 1-phosphate receptor 1. The active plasma metabolites of ozanimod bound to sphingosine 1-phosphate receptors 1 and 5 and displayed similar pharmacologic profiles as their parent compound, likely contributing to clinical efficacy in patients with relapsing multiple sclerosis or moderately to severely active ulcerative colitis.