Preparations and administration: natalizumab (Tysabri®) [58, 59] is approved for disease-modifying monotherapy of patients with highly

active RRMS in Europe and the United States (escalation therapy) in two subgroups of patients: Patients with high disease activity despite treatment with either IFN-β or GA. These patients PS-341 clinical trial should have had at least one relapse in the past 12 months and at least nine T2-hyperintense lesions or at least one gadolinum-enriching lesion on cerebral MRI. Patients with high disease activity showing at least two relapses with confirmed disability progression in the past 12 months and at least one gadolinum-enriching lesion or a significant increase in the number of T2-hyperintense lesions on cerebral MRI within the past 6–12 months. Natalizumab is administered intravenously at a dose of 300 mg Crizotinib in vivo every 4 weeks. Clinical trials: a recent Phase II clinical trial (study of SB-683699 compared to placebo in subjects

with RRMS) assessed the safety and efficacy of firategrast, a small oral anti-α4β-integrin molecule, in 343 patients with RRMS [60]. Patients received one of four treatments twice daily: firategrast 150 mg, firategrast 600 mg or firategrast 900 mg (women) or 1200 mg (men) or placebo. A 49% reduction (P = 0·0026) in the cumulative number of new gadolinium-enhancing MRI lesions was seen with 900 mg or 1200 mg of firategrast. In the 600 mg group, a non-significant 22% reduction (P = 0·2657)

occurred in the mean number of new gadolinium-enhanced lesions relative to placebo. Interestingly, in the 150 mg group, a significant 79% increase (P = 0·0353) occurred relative to placebo. In one case of CIDP, clinical and paraclinical effects of natalizumab treatment were studied [61]. T cells expressing the α4-integrin were found in the inflamed peripheral nerve, and natalizumab bound with high affinity to the α4-integrin on T lymphocytes. However, the patient’s clinical condition and paraclinical measures of disease activity deteriorated despite natalizumab treatment. Hence, natalizumab cannot be recommended in CIDP at present but warrants further exploration in future controlled clinical trials. Adenosine triphosphate Adverse effects, frequent: hypersensitivity reactions, elevations of liver enzymes; infrequent: treatment with natalizumab is associated with the risk of developing progressive multi-focal leukoencephalopathy (PML), i.e. an opportunistic infection of the CNS with the JC-virus that leads eventually to death (approximately 20%) or severe neurological sequelae [45, 46]. Risk of PML increases with long treatment duration (>2 years), preceding immunosuppressive treatment (independent from its duration and strength as well as the time interval to the natalizumab treatment), or a positive serological status for JC-virus [62].