A Study to Investigate Efficacy, Tolerability and Safety of ABY-035 in Patients With Active Psoriatic Arthritis

Inclusion criteria: * Patient who has given his / her signed declaration of consent and data protection declaration * At least 18 years and less than 75 years of age at Screening visit * Psoriatic arthritis with inflammatory musculoskeletal disease (joint, spine, or entheseal) with the presence of ≥3 points from the five categories of the Classification Criteria for Psoriatic Arthritis (CASPAR) at any timepoint in medical history. * Active psoriatic arthritis defined by: * ≥3 swollen joints out of 66 joints (SJC66) at Screening visit and Baseline visit * ≥3 tender joints out of 68 (TJC68) at Screening visit and Baseline visit * Precedent failure or insufficient treatment response to or contraindication or intolerability to nonsteroidal anti-inflammatory drug (NSAID), csDMARD (i.e. MTX, sulfasalazine, leflunomide, hydroxychloroquine, cyclosporine A), and/or TNFi (e.g. adalimumab, infliximab, etanercept, golimumab, certolizumab) * Rheumatoid factor (RF) and anti-CCP antibody negative * Presence or history of plaque psoriasis Exclusion Criteria: * Underlying conditions which significantly immunocompromise the patient and / or place the patient at unacceptable risk for receiving an immunomodulatory therapy * History of or current relevant autoimmune diseases (e.g. rheumatoid arthritis, primary ankylosing spondylitis, systemic lupus erythematosus) other than psoriasis or psoriatic arthritis * History of or current fibromyalgia or pain syndrome * Uncontrolled inflammatory bowel disease * Presence or history of recurrent or medically important infections in the last 6 months prior to Baseline visit * Clinically relevant Candida infection requiring systemic treatment within the last 6 months prior to Baseline visit * History or any signs of lymphoproliferative disease, or a known malignancy or a history of malignancy within the previous 5 years * Insufficiently controlled heart failure * Current uncontrolled arterial hyper- or hypotension