Background An unmet need remains for safe and effective long-term treatments of psoriasis. Objectives To evaluate ustekinumab efficacy and safety for up to 3 years in the PHOENIX 1 trial. Methods Patients (n = 766) with moderate-to-severe psoriasis were randomized to ustekinumab 45 mg or 90 mg at weeks 0 and 4, and then every 12 weeks, or placebo at weeks 0 and 4, with crossover to ustekinumab at week 12. Ustekinumab responders [≥ 75% improvement from baseline in the Psoriasis Area and Severity Index (PASI 75) at weeks 28 and 40] were re-randomized at week 40 to continue or withdraw from treatment until psoriasis recurrence. Partial responders (week 28: PASI 50-74; week 40: < PASI 75) switched to dosing every 8 weeks. Clinical efficacy was assessed by PASI, the Physician's Global Assessment (PGA), and the Dermatology Life Quality Index (DLQI) measures. Results Overall, 79·8% of the ustekinumab-treated patients remained in the study for 3 years. PASI 75 response rates (45 mg: 61·2%; 90 mg: 72·4%) at week 76 were maintained through year 3 (45 mg: 62·7%; 90 mg: 72·2%); PGA response was similarly durable. At year 3, 80·9% (45 mg) and 82·7% (90 mg) of week 40 responders continuing treatment every 12 weeks achieved a PASI 75 response, while 42·6% (45 mg) and 58·0% (90 mg) achieved a PASI 90 response. Among partial responders adjusted to dosing every 8 weeks, 50·9% (45 mg) and 52·0% (90 mg) had a PASI 75 response at year 3. DLQI responses paralleled the PASI responses. Through year 3, no dose response was observed in rates of adverse events (AEs), overall infections, serious AEs, or AEs leading to discontinuation; nor was there evidence of cumulative organ toxicity. Conclusions Continuous, stable, maintenance dosing with ustekinumab was generally well tolerated and sustained durable efficacy for up to 3 years of treatment.
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