A Phase 3 Multicenter, Randomized, Double-blind, Placebo controlled trial of

INTERVENTION:

Product Name: ustekinumab Product Code: CNTO1275 Pharmaceutical Form: Solution for injection Current Sponsor code: ustekinumab Other descriptive name: Human Anti‐IL‐12 Antibody Concentration unit: mg/ml milligram(s)/millilitre Concentration type: equal Concentration number: 90‐ Pharmaceutical form of the placebo: Solution for injection Route of administration of the placebo: Subcutaneous use

CONDITION:

Psoriatic Arthritis ; MedDRA version: 15.0 Level: LLT Classification code 10037160 Term: Psoriatic arthritis System Organ Class: 10028395 ‐ Musculoskeletal and connective tissue disorders

PRIMARY OUTCOME:

Main Objective: The primary objectives of this study are to evaluate the efficacy of ustekinumab in subjects with active PsA; by assessing the reduction in signs and symptoms of PsA and to evaluate the safety of ustekinumab in this population. Primary end point(s): The 2 coprimary endpoints are the proportion of subjects achieving an ACR 20 response at Week 24.; Secondary Objective: The secondary objectives of this study are to evaluate the efficacy of ustekinumab in:; 1. improving physical function;; 2. improving psoriatic skin lesions; and; 3. inhibiting the progression of structural damage.

INCLUSION CRITERIA:

Potential subjects must satisfy all of the following criteria to be enrolled in the study: • Men or women between 18 and 99 years of age, inclusive. • Have had PsA at least 6 months prior to the first administration of study agent. • Have a diagnosis of active PsA as defined by: – 5 or more swollen joints and 5 or more tender joints at screening and at baseline ‐AND‐ C‐reactive protein (CRP) = 0.3 mg/dL at screening. • Have at least 1 of the PsA subsets: DIP joint involvement, polyarticular arthritis with absence of rheumatoid nodules, arthritis mutilans, asymmetric peripheral arthritis, or spondylitis with peripheral arthritis. • Have active plaque psoriasis or a documented history of plaque psoriasis. • Have active PsA despite current or previous DMARD and/or NSAID therapy. DMARD therapy is defined as taking a DMARD for at least 3 months, or evidence of DMARD intolerance. NSAID therapy is defined as taking an NSAID for a