Efficacy and Safety of Tildrakizumab Compared to Placebo in Subjects With Active Psoriatic Arthritis I (INSPIRE 1)

Inclusion Criteria: 1. Subject has provided written informed consent. 2. Subject is ≥ 18 years of age at time of Screening. 3. RF and anti-CCP Ab negative. 4. Subjects must have prior exposure to anti-TNF agent(s) use for the treatment of PsO or PsA. Exclusion Criteria: 1. Subject has a planned surgical intervention between Baseline and the Week 24 evaluation for a pretreatment condition. 2. Subject has an active infection or history of infections as follows: * any active infection for which systemic anti-infectives were used within 28 days prior to first IMP dose, with the last dose having been received within 7 days of Screening, * a serious infection, defined as requiring hospitalization or IV anti-infectives within 8 weeks prior to the first IMP dose, with the last dose having been received within 7 days of Screening, * recurrent or chronic infections, e.g., chronic pyelonephritis, chronic osteomyelitis, bronchiectasis, or other active infection that, in the opinion of the Investigator, might cause this study to be detrimental to the subject. 3. Subject has a known history of infection with hepatitis B, hepatitis C, or human immunodeficiency virus. 4. Subject had myocardial infarction, unstable angina pectoris, or ischemic stroke within the past 6 months prior to the first IMP dose. 5. Subject has any active malignancy, including evidence of cutaneous basal or squamous cell carcinoma or melanoma. 6. Subject has a history of malignancy within 5 years from the time of Screening EXCEPT treated and considered cured cutaneous basal or squamous cell carcinoma, in situ cervical carcinoma, OR in situ breast ductal carcinoma. 7. Subjects with a history of alcohol or drug abuse in the previous 2 years. 8. Female subjects of childbearing potential who do not agree to abstain from heterosexual activity or practice a dual method of contraception, for example, a combination of the following: (1) oral contraceptive, depo progesterone, or intrauterine device; and (2) a barrier method (condom or diaphragm). Male subjects with female partners of childbearing potential who are not using birth control as described above must use a barrier method of contraception (e.g., condom) if not surgically sterile (i.e., vasectomy). Contraceptive methods must be practiced upon entering the study and through 17 weeks after the last dose of IMP. If a subject discontinues prematurely, the contraceptive method must be practiced for 17 weeks following final administration of IMP. A FSH test should be performed to confirm menopause for those women with no menses for less than 1 year. 9. Subject currently enrolled in another investigational device/procedure or drug study, or Baseline of this study is less than 30 days or 5 half-lives (whichever is longer) since ending another investigational device/procedure or drug study(s), or receiving other investigational agent(s). 10. Subject previously has been enrolled (randomized) in this study. 11. Subject has any kind of disorder that, in the opinion of the Investigator, may compromise the ability of the subject to give written informed consent and/or to comply with all required study procedures. 12. Donation or loss of 400 mL or more of blood within 8 weeks before dosing. 13. Subjects who have been placed in an institution on official or judicial orders. 14. Subjects who are related to or dependent on the Investigator, Sponsor, or study site such that a conflict of interest could arise.