Inclusion Criteria:  Participant has PsA for at least 6 months prior to the first administration of the study drug and meets classification criteria for PsA (CASPAR) at Screening. Participant has active PsA defined by the presence of ≥3 of 68 tender joint counts and ≥3 of 66 swollen joint counts at Screening and Randomization. Participant has active PsA at Screening despite previous DMARD or NSAID therapy. DMARD therapy is defined as taking DMARD for at least 3 months, or evidence of DMARD intolerance. NSAID therapy is defined as taking an NSAID for at least 4 weeks (or have intolerance to or contraindication to NSAID therapy). Participant has at least 1 active psoriatic lesion with a qualifying lesion of at least 2 cm in diameter at Screening and Randomization. Participant is negative for rheumatoid factor and anti-cyclic citrullinated peptide (ACCP) antibodies at Screening.  Exclusion Criteria:  Participant is currently receiving or has previously received any biological agent or targeted disease modifying anti-rheumatic drugs (DMARDs) for the treatment of PsA or psoriasis. Participant has previously received any other nonbiological DMARDs (apart from MTX), including sulfasalazine, hydroxychloroquine or apremilast within 8 weeks prior to the first administration of the study drug; or has previously received leflunomide within 12 weeks (except at least 4 weeks prior to the first administration of the study drug, the subject has documented completion of standard cholestyramine or activated charcoal washout procedure). Participant has received epidural, intra-articular, intramuscular, or intravenous (IV) corticosteroids during the 4 weeks prior to first administration of study drug. Participant has been treated with cytotoxic agents, (including but not limited to azathioprine, cyclosporine, cyclophosphamide), nitrogen mustard, chlorambucil, or other alkylating agents within 6 months prior to the first administration of the study drug. Participant has received or is expected to receive any live vaccinations from 3 months before first study drug administration and up to 3 months after the last study drug administration. Participant has received other therapeutic infectious agents within 8 weeks prior to first dose or expected to receive other therapeutic infectious agents during the study until SFU. Participant has received IV immunoglobulins or plasmapheresis within 6 months prior to the first administration of the study drug.