A Phase 2 Study to Investigate the Safety, Tolerability and Efficacy of ABT-122 in Subjects With Active Psoriatic Arthritis Who Have an Inadequate Response to Methotrexate

Inclusion Criteria:

- PsA diagnosis of at least 3 months duration prior to the date of first screening with
ClASsification of Psoriatic ARthritis (CASPAR) confirmed diagnosis at Screening.

- Have active psoriasis defined by at least 1 psoriasis lesion >= 2 cm diameter in
areas other than the axilla or groin.

- Have active arthritis defined by minimum disease activity criteria:

1. >= 3 Swollen joints (based on 66 joint counts) at Screening

2. >= 3 Tender joints (based on 68 joint counts) at Screening

- On a stable dose of methotrexate (MTX) defined as:

1. Oral or parenteral treatment >= 3 months,

2. On a stable dose with an unchanged mode of application for at least 4 weeks
prior to baseline

3. Stable MTX dose of >= 10 mg/week and <= the upper limit of the applicable
approved local label.

4. Subject can also be on stable doses of nonsteroidal anti-inflammatory drugs
(NSAIDs), sulfasalazine and/or hydroxychloroquine as long as they are also on
methotrexate.

Exclusion Criteria:

- Prior exposure to any tumor necrosis factor (TNF) inhibitors including:

- Up to 30% (approximately 66 subjects) with prior exposure to a TNF inhibitor may be
enrolled if the TNF inhibitor was not discontinued due to lack of efficacy or safety
concerns. Subjects must be washed out for at least 5 half-lives of these drugs prior
to the Baseline visit.

1. Subjects on prior adalimumab may not be enrolled in the study.

2. Prior exposure to other non-TNF inhibitor biological disease-modifying
antirheumatic drugs (DMARDs) will be permitted if the subject is washed out at
least 5 half-lives of these drugs prior to the baseline visit.

- Current treatment with traditional oral DMARDs, including conventional synthetic
DMARDs (csDMARDs), (except for concomitant treatment with sulfasalazine and/or
hydroxychloroquine in addition to MTX). Oral DMARDs must be washed out for at least 5
half-lives of a drug apart from MTX prior to the Baseline visit.

a. Subject could have been exposed to prior Janus kinase (JAK) inhibitors so long as
they have been off therapy for at least 5 half-lives.

- Stable prescribed dose of oral prednisone or prednisone equivalent > 10 mg/day within
the 30 days of the Baseline visit.

- Intra-articular or parenteral administration of corticosteroids in the preceding 4
weeks of the Baseline visit. Inhaled corticosteroids for stable medical conditions
are allowed.

- Laboratory values of the following at the Screening Visit:

1. Confirmed hemoglobin < 9 g/dL for males and < 8.5 g/dL for females,

2. Absolute neutrophil count (ANC) < 1500 mm3, (or < 1200 cells/µL for subjects of
African descent who are black),

3. Aspartate aminotransferase (AST) or alanine aminotransferase (ALT) > 1.5 x the
upper limit of normal (ULN) or bilirubin >= 3 mg/dL,

4. Serum creatinine > 1.5 x the ULN,

5. Platelets < 100,000 cells/[mm3] (109/L),

6. Clinically significant abnormal screening laboratory results as evaluated by the
Investigator