Siponimod

Inflammation of the white and gray matter tissues in the central nervous system caused by localized immune cell infiltration and their cytokines are the initial cause of damage in MS. B lymphocytes and their cytokines are other factors in the pathogenesis of MS. Lymphotoxin [or transforming growth factor beta (TGF-β)] and TNF-α produced by these cells encourage inflammation. The S1P receptor is an important receptor related to the function of lymphocytes and can be found in the central nervous system. S1P receptor (S1PR) signaling is associated with a wide variety of physiological processes for lymphocytes, including their egress and recirculation.

Siponimod is classified as a sphingosine-1-phosphate (S1P) receptor modulator. Siponimod binds with high affinity to both S1P receptors 1 and 5. This drug blocks the ability of lymphocytes to release from the lymph nodes, decreasing the number of lymphocytes found in the peripheral blood. The mechanism by which siponimod exerts therapeutic effects in multiple sclerosis is not known at this time, but may involve the abovementioned decrease of lymphocytes into the central nervous system, decreasing the inflammatory effects of MS.