2 The technology
2.1 Natalizumab (Tysabri, Biogen Idec and Elan Pharma International Ltd) has a marketing authorisation as a single disease-modifying therapy in highly active relapsing–remitting multiple sclerosis for the following groups.
Patients with rapidly evolving severe relapsing–remitting multiple sclerosis defined by two or more disabling relapses in 1 year, and one or more gadolinium-enhancing lesions on brain MRI or a significant increase in T2 lesion load compared with a previous MRI. This patient group is referred to as the 'RES group'.
Patients with high disease activity despite treatment with beta interferon. This group is defined as patients who have failed to respond to a full and adequate course of a beta interferon. Patients should have had at least one relapse in the previous year while on therapy, and have at least nine T2-hyperintensive lesions in cranial MRI or at least one gadolinium-enhancing lesion. This patient group is referred to as the 'suboptimal therapy group'.
2.2 The use of natalizumab may be associated with infections, urticaria, headache, dizziness, vomiting, nausea, arthralgia, infusion reactions and hypersensitivity reactions. Natalizumab has also been associated with an increased risk of progressive multifocal leukoencephalopathy (PML). For full details of side effects and contraindications, see the summary of product characteristics.
2.3 Natalizumab is administered by intravenous infusion; the recommended dose is 300 mg every 28 days. Natalizumab costs £1130 per 300 mg vial (according to the manufacturer's submission), so over a year the cost of the drug is approximately £14,730 per patient. Costs may vary in different settings because of negotiated procurement discounts. The manufacturer expects that monitoring for symptoms of immunogenicity (anti-natalizumab antibodies) and hypersensitivity will be needed.