Natalizumab for the treatment of highly active MS: risks and benefits

Multiple sclerosis (MS) is the most common neurological disease in young adults, affecting about 100 000 people in the UK (MS Trust, 2018). MS is an autoimmune disease of the central nervous system (CNS), which causes demylenation. Its symptoms result from inflammatory injury and neurodegeneration. In MS, autoreactive lymphocytes cross the blood brain barrier (BBB) and enter the CNS, causing inflammation, neuronal demyelination, axonal damage, and neurological degeneration and dysfunction (Bradstander and Katz Sand, 2017).

MS is classified into three main types: relapsing remitting multiple sclerosis (RRMS), secondary progressive multiple sclerosis (SPMS) and primary progressive multiple sclerosis (PPMS). RRMS affects 85% of the MS population (MS Trust, 2018). It is categorised by episodes of new or worsening symptoms that last for more than 48 hours (relapse) followed by periods of recovery and remission (remission). This type of MS is more prevalent in 20–30-year-old women. There are a number of disease modifying therapies (DMTs) that aim to reduce the impact of relapses and the accumulation of disability. Each of these treatments has different mode of action, efficacy, route of administration and licencing criteria. The medication chosen for someone with MS will be a decision for the patient and their neurologist to make together by looking at the patient's disease activity, lifestyle and life choices (ie starting a family) (NHS England, 2018).