Long‐Term Efficacy and Safety of Guselkumab, a Monoclonal Antibody Specific to the p19 Subunit of Interleukin‐23, Through Two Years: Results From a Phase III, Randomized, Double‐Blind, Placebo‐Controlled Study Conducted in Biologic‐Naive Patients With Active Psoriatic Arthritis

OBJECTIVE: To assess long-term efficacy and safety of guselkumab, an interleukin-23 p19 subunit (IL-23p19) inhibitor, in patients with active psoriatic arthritis (PsA) from the phase III DISCOVER-2 trial. METHODS: In the DISCOVER-2 trial, patients with active PsA (≥5 swollen joints and ≥5 tender joints; C-reactive protein level ≥0.6 mg/dl) despite prior nonbiologic therapy were randomized to receive the following: guselkumab 100 mg every 4 weeks; guselkumab 100 mg at weeks 0 and 4 and then every 8 weeks; or placebo with crossover to guselkumab 100 mg every 4 weeks, beginning at week 24. Efficacy assessments included American College of Rheumatology ≥20%/50%/70% improvement criteria (ACR20/50/70), Investigator's Global Assessment (IGA) of psoriasis score of 0 (indicating complete skin clearance), resolution of enthesitis (Leeds Enthesitis Index) and dactylitis (Dactylitis Severity Score), and changes in the Sharp/van der Heijde modified radiographic scores for PsA. Clinical data (imputed as no response/no change from baseline if missing) and observed radiographic data were summarized through week 100; safety assessments continued through week 112. RESULTS: Of the 739 randomized and treated patients, 652 (88%) completed treatment through week 100. Across groups of guselkumab-treated patients (including those in the placebo-guselkumab crossover group), the following findings at week 100 indicated that amelioration of arthritis signs/symptoms and extraarticular manifestations was durable through 2 years: ACR20 response (68-76%), ACR50 response (48-56%), ACR70 response (30-36%), IGA score of 0 (55-67%), enthesitis resolution (62-70%), and dactylitis resolution (72-83%). Mean changes in the Sharp/van der Heijde modified score for PsA from weeks 52 to week 100 (range 0.13-0.75) indicated that the low rates of radiographic progression observed among guselkumab-treated patients at earlier time points extended through week 100. Through week 112, 8% (5.8 per 100 patient-years) and 3% (1.9 per 100 patient-years) of the 731 guselkumab-treated patients had a serious adverse event or serious infection, respectively; 1 death occurred (road traffic accident). CONCLUSION: In biologic-naive PsA patients, guselkumab provided durable improvements in multiple disease domains with no unexpected safety findings through 2 years.