Ustekinumab (Stelara®) received FDA approval in September 2013 for a new indication of the treatment of adults with active psoriatic arthritis (PsA), alone or in combination with methotrexate. Already indicated for the treatment of adults with moderate-to-severe plaque psoriasis, ustekinumab is a human IgG1κ monoclonal antibody against the p40 subunit of IL12/23. In the pivotal PSUMMIT 1 trial, a phase 3, multicenter, randomized controlled trial of adults with active PsA (≥ 5 tender joints, ≥ 5 swollen joints, C-RP ≥ 3.0 m/L, and active or documented history of plaque psoriasis) fulfilling CASPAR criteria, subjects (N=615) were randomized (1:1:1) to receive ustekinumab 45 mg, ustekinumab 90 mg, or placebo subcutaneously at weeks 0, 4, and then every 12 weeks thereafter. The primary study endpoint was ACR20 response at week 24. A significantly higher proportion of patients in both active treatment groups achieved an ACR20 response compared to placebo (42% in the ustekinumab 45 mg group, 50% in the ustekinumab 90 mg group, and 23% in placebo, p<0.0001). Efficacy was maintained through week 52. Subjects assigned to placebo and who then crossed over to active drug (ustekinumab 45 mg or 90 mg) at week 16 were able to attain a similar ACR20 response at week 52 compared to those who received active drug throughout. Active plaque psoriasis improved significantly among those who received ustekinumab, with 57% among the 45 mg group and 62% among the 90 mg group achieving a PASI75 compared to 11% among placebo (p<0.0001). Dactylitis and enthesitis were both significantly improved in subjects receiving ustekinumab as compared to placebo. Risk of adverse events, including nasopharyngitis, upper respiratory tract infection, headache, and fatigue, was similar for all groups. Before starting treatment with ustekinumab for PsA, patients should be screened for TB. The recommended dose is 45 mg subcutaneously at weeks 0, 4, and then every 12 weeks thereafter. For those with co-existing moderate-to-severe plaque psoriasis weighing > 100 kg, the recommended dose is 90 mg at the aforementioned time intervals.
References:
- McInnes IB, Kavanaugh A, Gottlieb AB, et al. Lancet 2013;382:780-9.
- Ustekinumab Package Insert (www.stelarainfo.com/pdf/PrescribingInformation.pdf)
