Relapsing-remitting multiple sclerosis (RRMS)
Other autoimmune diseases
Sphingosine-1-phosphate (S1P) receptor modulator
Phase 1 clinical trial in the UK is ongoing.
What is multiple sclerosis (MS)?
- Although the cause of disease is unknown, MS is classified as an autoimmune disease of the central nervous system. In MS, the myelin that insulates and protects the nerve cells of the brain and spinal cord become damaged as described below. Accordingly, electrical impulses from the brain do not flow smoothly to the target nerve.
(1) Lymphocytes exit the lymph nodes and enter the blood circulation; they then invade the central nervous system.
(2) Lymphocytes destroy the myelin encasing nerve cells and induce “demyelination.”
(3) “Demyelination” causes various neurologic symptoms, and attacks, called relapses, are usually followed by partial or complete recovery.
The main symptoms are as follows:
loss of sensitivity, blurred vision, tingling and numbness, movement disorder, difficulty with balance and co-ordination, bladder and bowel difficulties, fatigue, cognitive impairment and emotional problems
- It is estimated that there are 2.5 million people worldwide who have been diagnosed with MS. It is common in Europe and North America, but not in Asia and Africa.
In Japan, MS has been designated as an incurable disease by the Ministry of Health, Labour and Welfare. An estimated 13,000 individuals have MS and this number has been increasing in recent years.
Mechanism of S1P receptor modulator
- An S1P receptor modulator regulates lymphocyte egress by binding to S1P receptor on the surface of lymphocytes and thereby exhibits immunosuppressive effects as below.
(1) An S1P receptor modulator combines with an S1P receptor on the surface of lymphocytes in lymph nodes.
(2) Lymphocytes are prevented from entering the blood circulation and thus remain in the lymph nodes.
(3) As a result, lymphocytes do not invade the central nervous system and the occurrence of “demyelination” is averted.