Efficacy and safety of secukinumab in the treatment of moderate-to-severe plaque psoriasis: a randomized, double-blind, placebo-controlled phase II dose-ranging study

Background: Conventional systemic therapies for plaque psoriasis have not fully met the needs of patients, and although current biologic treatments are generally well tolerated, concerns exist with respect to long-term safety. Interleukin (IL)-17A is believed to be an important effector cytokine in the pathogenesis of psoriasis and is produced by Th17 cells, a class of helper T cells that act outside the established Th1/Th2 paradigm for regulation of innate and adaptive immunity.

Objectives: To assess the efficacy and safety of different doses of secukinumab, a fully human anti-IL-17A IgG1κ monoclonal antibody, in patients with moderate-to-severe plaque psoriasis.

Methods: Patients (n = 125) were randomized 1 : 1 : 1 : 1 : 1 to receive subcutaneous doses of placebo (n = 22) or secukinumab [1 × 25 mg (n = 29), 3 × 25 mg (n = 26), 3 × 75 mg (n = 21) or 3 × 150 mg (n = 27)] at weeks 0, 4 and 8. After the 12-week treatment period, patients entered a follow-up period of 24 weeks. The primary efficacy outcome was at least 75% improvement from baseline in the Psoriasis Area and Severity Index score (PASI 75); secondary outcomes included the Investigator's Global Assessment (IGA) and PASI 90 and 50 response rates.

Results: After 12 weeks of treatment, secukinumab 3 × 150 mg and 3 × 75 mg resulted in significantly higher PASI 75 response rates vs. placebo (82% and 57% vs. 9%; P < 0·001 and P = 0·002, respectively). Higher PASI 75 response rates compared with placebo were maintained throughout the follow-up period with these dosages [week 36, 26% (n = 7) and 19% (n = 4) vs. 4% (n = 1), respectively], with a gradual decline of PASI 75 response over time after the dosing period. IGA response rates were significantly higher in the 3 × 150 mg group vs. placebo at week 12 (48% vs. 9%; P = 0·005) and were consistently higher for the 3 × 150 mg and 3 × 75 mg groups vs. placebo at all time points from week 4 onward. The PASI 90 response rate was significantly higher in the 3 × 150 mg group vs. placebo (52% vs. 5%) at week 12 and remained higher during the follow-up period. Secukinumab was well tolerated. Two cases of neutropenia (≤ grade 2) were reported in the 3 × 150 mg cohort.

Conclusions: Treatment with subcutaneous secukinumab 3 × 75 mg and 3 × 150 mg met the primary outcome of PASI 75 response achievement after 12 weeks, demonstrating efficacy in moderate-to-severe psoriasis.