Study of Efficacy and Safety of Secukinumab in Chinese Subjects With Active PsA Compared to Placebo.

Inclusion Criteria: * Participant must be able to understand and communicate with the investigator and comply with the requirements of the study and must give a written, signed and dated informed consent before any study assessment is performed. * Chinese male or non-pregnant, non-lactating Chinese female participants at least 18 years of age. * Diagnosis of PsA classified by Classification of Psoriatic Arthritis (CASPAR) criteria and with symptoms for at least 6 months with moderate to severe Psoriatic arthritis (PsA). * Rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibodies negative at screening. * Diagnosis of active plaque psoriasis or nail changes consistent with psoriasis or a documented history of plaque psoriasis. * Participants on Methotrexate (MTX) must be on folic acid supplementation at randomization. * Participants who are on a DMARD other than MTX must discontinue the DMARD 4 weeks prior to randomization visit except for leflunomide, which has to be discontinued for 8 weeks prior to randomization unless a cholestyramine washout has been performed. Exclusion Criteria: * Chest X-ray or chest MRI with evidence of ongoing infectious or malignant process, obtained within 3 months prior to screening and evaluated by a qualified physician * Participants taking high potency opioid analgesics (e.g., methadone, hydromorphone, morphine). * Previous exposure to secukinumab or other biologic drug directly targeting interleukin- 17 (IL-17) or IL-17 receptor * Participants who have ever received biologic immunomodulating agents except for those targeting Tumor necrosis factor alpha (TNFα). * Women of child-bearing potential, defined as all women physiologically capable of becoming pregnant, unless they are using effective contraception during the entire study (during the entire study).