When should second-line treatment of multiple sclerosis be started?

The aim of relapsing-remitting multiple sclerosis therapy is to achieve the maximum clinical effect of reducing the number of or eliminating relapses of the disease and achieving the lack of progression of physical disability with a minimum or nonexistent disease activity observed in magnetic resonance imaging. Treatment should be started as soon as possible in order to limit the inflammatory and autoimmune process which leads to neurodegenerative lesions. There are a number of first-line medicines which are used at the beginning of the disease such as interferon beta and glatiramer acetate. Oral drugs have recently been introduced into this group such as dimethyl fumarate and teriflunomide, among others. They are characterised by a good safety profile and moderate efficacy. If first-line therapies turn out to be ineffective, second-line medicines are used such as, for example, natalizumab or fingolimod. The views on when second-line therapy should be started and what substances to use have been constantly evolving and the recommendations sometimes differ depending on the country. For instance, fingolimod was approved by the European Medicines Agency as a second-line therapy for relapsing-remitting multiple sclerosis, while Food and Drug Administration approved it as a first-line therapy for this disease. When selecting a medicine one should take into account disease activity, the efficacy of the treatment used so far, comorbidities as well as potential side effects.