This is a 12-week study to assess the safety, tolerability, pharmacokinetics and pharmacodynamics of oral CS-0777 in patients with Multiple Sclerosis.

Inclusion Criteria:

• Diagnosis of clinically isolated syndrome or a relapsing form(s) of MS, based on Poser or McDonald criteria (may include patients with secondary progressive disease)
• Clinical relapse within the past 3 years or a gadolinium enhancing lesion on a brain MRI scan within the past 12 months
• Baseline EDSS score of 0 - 6.5
• Female subjects who are sexually active, unless sterile or post-menopausal for at least 1 year, must be willing to use double-barrier contraception

Exclusion Criteria:

• Primary progressive MS
• Any medical condition that predisposes to immunocompromise
• History of malignancy, tuberculosis, invasive fungal infections, herpes zoster infection (or shingles), or other opportunistic infection, or any current active infection
• Concurrent diagnosis of any other autoimmune disease (eg, rheumatoid arthritis or lupus)
• Treatment with cyclophosphamide or mitoxantrone within 6 months of study initiation
• Treatment with cyclosporine, azathioprine, methotrexate or other immunosuppressant within 3 months of study initiation
• Treatment with interferon beta or glatiramer acetate within 2 months of study initiation
• Prior treatment with natalizumab or rituximab