The primary objective of this study is to evaluate the efficacy of brodalumab, compared to placebo, in subjects with psoriatic arthritis. The key secondary objective is to evaluate the efficacy of brodalumab compared to placebo at week 16. The safety objective of this study is to evaluate the safety profile of brodalumab in subjects with psoriatic arthritis.

Inclusion Criteria:

Subjects has a diagnosis of psoriatic arthritis (by the Classification of Psoriatic Arthritis criteria (CASPAR), with ≥ 3 tender and ≥ 3 swollen joints (excluding distal interphalangeal joints). Subjects must have at least

1 psoriatic skin lesion. Exclusion Criteria:

• -Subject has known history of active tuberculosis.

• Subject has a planned surgical intervention between baseline and the week 52 evaluation.
• Subject has an active infection or history of infections.
• Subject has any systemic disease (eg, renal failure, heart failure, hypertension, liver disease, diabetes, anemia) considered by the Investigator to be clinically significant and uncontrolled.
• Subject has any concurrent medical condition or electrocardiogram (ECG) abnormality that, in the opinion of the investigator, could cause this study to be detrimental to the subject.

Subject has severe depression measured by Personal Health Questionnaire Depression Scale (PHQ-8) or suicidal ideation/behavior as measured by and Columbia Suicide Severity Rating Scale (e-CSSRS)

• Subject has a history or evidence of psychiatric disorder or substance abuse considered by the Investigator to pose a risk to subject safety