2 The technology
2.1 Ustekinumab (Stelara, Janssen-Cilag) is a fully human monoclonal antibody that targets interleukin-12 (IL-12) and IL-23. It binds to the p40 subunit, common to both IL-12 and IL-23, which prevents these cytokines from binding to the cell surface of T cells, thereby disrupting the inflammatory cascade implicated in psoriasis. Ustekinumab has a UK marketing authorisation for 'the treatment of moderate to severe plaque psoriasis in adults who have failed to respond to, or who have a contraindication to, or are intolerant to other systemic therapies including ciclosporin, methotrexate and PUVA'. The recommended dose of ustekinumab is 45 mg for people who weigh 100 kg or less, and 90 mg for people who weigh over 100 kg. An initial dose of ustekinumab is administered subcutaneously at week 0, followed by another dose at week 4, and then a further dose every 12 weeks. The summary of product characteristics (SPC) states that ustekinumab is intended for use under the guidance and supervision of a physician experienced in the diagnosis and treatment of psoriasis.
2.2 Common adverse events associated with ustekinumab, as reported in the SPC, include upper respiratory tract infection, nasopharyngitis, depression, headache, dizziness, diarrhoea, pruritus, back pain, fatigue and injection site erythema. Contraindications listed in the SPC include clinically important active infection and hypersensitivity to the active substance or to any of the excipients. For full details of side effects and contraindications, see the SPC.
2.3 Ustekinumab is available in vials containing 45 mg. The cost per vial is £2147 (Monthly Index of Medical Specialities [MIMS], April 2009). Ustekinumab is not listed in the current version of the 'British national formulary' (BNF; edition 57). The cost of ustekinumab for the two loading doses (at 0 and 4 weeks) is £4294. The cost in the first year is £10,735, with an annual cost thereafter of £9335 (the annual cost assumes an average of 4.3 injections per year). Costs may vary in different settings because of negotiated procurement discounts.
2.4 The SPC recommends that people whose body weight exceeds 100 kg should receive a dose of 90 mg of ustekinumab. This would be double the cost of the 45 mg dose indicated for the treatment of a person who weighs 100 kg or less. However, the manufacturer has proposed a patient access scheme to the Department of Health. Under the scheme, for people who weigh more than 100 kg and who are prescribed the 90 mg dose (two 45 mg vials), the manufacturer will provide both vials at a total cost of £2147 (the cost of a single vial). The manufacturer has proposed that this patient access scheme will be available to the NHS at least until either a review of the guidance by NICE or the introduction of any new formulations that would render the scheme obsolete. The Department of Health considered that this patient access scheme does not constitute an excessive administrative burden on the NHS. The patient access scheme was withdrawn in January 2017 because the company now provides a 90‑mg vial at the same cost as the 45‑mg vial.