Efficacy and Safety of Guselkumab, an Interleukin‐23p19–Specific Monoclonal Antibody, Through One Year in Biologic‐Naive Patients With Psoriatic Arthritis

OBJECTIVE: Guselkumab, a human monoclonal antibody specific to interleukin‐23p19, demonstrated efficacy and safety versus placebo through week 24 of the phase III DISCOVER‐2 trial in biologic‐naive patients with psoriatic arthritis (PsA). Here we report 1‐year DISCOVER‐2 findings. METHODS: Adults with active PsA (≥5 swollen and ≥5 tender joints; C‐reactive protein level ≥0.6 mg/dl) despite standard nonbiologic treatment were randomized to receive subcutaneous injections of guselkumab 100 mg every 4 weeks, guselkumab 100 mg at week 0, week 4 and every 8 weeks thereafter, or placebo with crossover to guselkumab 100 mg every 4 weeks at week 24. We primarily evaluated clinical efficacy through week 52 by imputing missing data (nonresponse for categorical end points; no change/using multiple imputation for continuous end points). Observed radiographic scores and adverse events (AEs) were summarized. RESULTS: Of 739 randomized, treated patients, 93% completed week 52. The proportions of patients in whom a ≥20% improvement from baseline in American College of Rheumatology criteria (ACR20) was achieved were maintained after week 24, reaching 71% (173 of 245) and 75% (185 of 248) for patients randomized to receive treatment every 4 weeks or every 8 weeks, respectively, by week 52. The proportions of patients in whom ACR50/ACR70 and skin responses, minimal or very low disease activity, and dactylitis or enthesitis resolution were achieved at week 24 were also maintained through week 52. Further, low levels of radiographic progression, along with improvements in physical function and health‐related quality of life, were sustained through week 52 with continued guselkumab treatment. Few patients experienced serious infections through week 52, with no evidence of a dosing regimen response or increase from weeks 0–24 (4 of 493 [0.8%]) to weeks 24–52 (3 of 493 [0.6%]) among guselkumab‐randomized patients. No patient developed an opportunistic infection or died. CONCLUSION: In biologic‐naive PsA patients, guselkumab provided sustained improvements across diverse manifestations and maintained a favorable risk–benefit profile through week 52.