Combination therapy in multiple sclerosis.

Multiple sclerosis (MS) is an autoimmune disease of the CNS. It is the most common non-traumatic cause of neurological disability among young adults in western Europe and North America. Existing MS therapies are partly effective in halting ongoing inflammatory tissue damage and clinical progression. MS pathogenesis is complex and probably heterogeneous among patients, suggesting that combination therapy strategies that target a range of disease mechanisms might be more effective than medications used as monotherapy. Potential regimens include the combination of interferons and glatiramer acetate with each other or with approved second-line drugs such as natalizumab and mitoxantrone. Disease-modifying therapies have also been used in combination with drugs approved for other indications, such as corticosteroids, methotrexate, azathioprine, and cyclophosphamide. Many preliminary studies have provided favourable results for various combination regimens. However, several subsequent large, randomised, controlled trials have had negative or conflicting results. Therefore, the usefulness of combination therapy in MS remains uncertain.