ObjectiveTo investigate the safety and efficacy of ABT‐122, a tumor necrosis factor (TNF)– and interleukin‐17A (IL‐17A)–targeted dual variable domain immunoglobulin, in patients with active psoriatic arthritis (PsA) who have experienced an inadequate response to methotrexate.MethodsPatients (n = 240) were randomized to receive ABT‐122 (120 or 240 mg every week), adalimumab (40 mg every other week), or placebo in a 12‐week double‐blind, parallel‐group study. The primary efficacy end point was the proportion of patients achieving ≥20% improvement in disease activity according to the American College of Rheumatology response criteria (ACR20) at week 12. Secondary and exploratory 12‐week end points included 50% improvement (ACR50) and 70% improvement (ACR70) response rates, and proportion of patients meeting the Psoriasis Area and Severity Index (PASI) response criteria for ≥75% (PASI75) and ≥90% (PASI90) improvement in skin scores among those with ≥3% of their body surface area affected by psoriasis.ResultsIn both ABT‐122 dose groups, ACR20 response rates at week 12 (64.8–75.3%) were superior to that in patients receiving placebo (25.0%) (P < 0.001) but similar to that in patients receiving adalimumab (68.1%). ACR50 and ACR70 response rates were also superior in both ABT‐122 dose groups (36.6–53.4% and 22.5–31.5%, respectively) compared to the placebo group (12.5% and 4.2%, respectively) (P < 0.05). Among eligible patients in the placebo, adalimumab, ABT‐122 120 mg every week, and ABT‐122 240 mg every week treatment groups, PASI75 responses were achieved in 27.3%, 57.6%, 74.4%, and 77.6% of patients, respectively, whereas PASI90 responses were achieved in 18.2%, 45.5%, 48.8%, and 46.9% of patients, respectively. Frequencies of treatment‐emergent adverse events, including infections, were similar across all treatment groups, causing no discontinuations. No serious infections or systemic hypersensitivity reactions were reported with ABT‐122.ConclusionDual neutralization of TNF and IL‐17A with ABT‐122 had efficacy and safety that was similar to, and not broadly differentiated from, that of adalimumab over a 12‐week treatment course in patients with PsA.