Background  Ongoing evaluation of biological agents in patients with moderate-to-severe psoriasis is needed to support their long-term use.

Objective  To evaluate long-term efficacy and safety of ustekinumab through 5 years in the PHOENIX 1 study.

Methods  Patients were randomized to placebo or ustekinumab (45 mg or 90 mg) at Weeks 0, 4 and every-12-weeks thereafter; placebo patients crossed-over to ustekinumab at Week 12. Clinical response through Week 244 was evaluated using the Psoriasis Area and Severity Index (PASI) in the Overall Population (i.e. patients receiving ≥1 dose of ustekinumab), Initial Responders (i.e. PASI 75 responders [Weeks 28/40] re-randomized at Week 40 to continue every-12-week maintenance) and Partial Responders (i.e. <PASI 75 responders adjusted to every-8-week maintenance at Weeks 28 or 40). Safety endpoints were evaluated through Week 264 for the Overall Population.

Results  Overall, 68.7% (517/753) of ustekinumab-treated patients completed treatment through Week 244. Initial clinical responses were generally maintained through Week 244 (PASI 75: 63.4% and 72.0%; PASI 90: 39.7% and 49.0%; PASI 100: 21.6% and 26.4%) for patients receiving 45 mg and 90 mg, respectively. Similarly, PASI 75 responses were generally maintained among Initial Responders [79.1% (45 mg) and 80.8% (90 mg)] and Partial Responders [57.6% (45 mg) and 55.1% (90 mg)]. With 3104 patient-years of follow-up, rates of overall adverse events (AEs), serious AEs, serious infections, malignancies and major adverse cardiovascular events were generally consistent over time and comparable between doses.

Conclusions  Through 5 years of continuous treatment, ustekinumab demonstrated stable clinical response and a safety profile consistent with previous reports.