Clinical Trial Finder

Inclusion Criteria:

1. Subject has provided written informed consent for this long-term extension study. 2. Subjects with psoriatic arthritis (PsA) and ankylosing spondylitis (AS) or non-radiographic axial spondyloarthritis (nr-axSpA) who met the inclusion criteria of the parent studies and completed the parent study treatment period (e.g., up to Week 48 for the parent Phase 2 studies, with the return for the end of treatment (EoT) assessment at Week 52). 3. PsA subjects who achieved a 20% reduction from Baseline in ACR20 response criteria at Week 52, and AS or nr-axSpA subjects who achieved ASAS40 response criteria at Week 52, AND the subject has received sufficient clinical benefit, in the opinion of the Investigator, to support continued treatment with tildrakizumab. These criteria using response criteria at Week 52 will apply to all subjects, including those subjects who enter the study from the wash-out phase of their parent study (after Week 52) due to the timing of study site activation of the long-term extension study. 4. No concomitant use of both leflunomide and methotrexate, No history of active tuberculosis (TB) or symptoms of TB.

Exclusion Criteria:

1. New onset during the parent study of arthritic conditions other than the subject's original condition. 2. 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 practised upon entering the study and through 16 weeks after the last dose of IMP. If a subject discontinues prematurely, the contraceptive method must be practised for 16 weeks following final administration of IMP. 3. Female is pregnant or breastfeeding, or planning to become pregnant or initiate breastfeeding while enrolled in the study or up to 16 weeks after the last dose of IMP. 4. Subject has previously been enrolled in this long-term extension study. 5. Any condition that in the opinion of the Investigator represents an obstacle for study conduct and/or represents a potential unacceptable risk for the subject. 6. Subject has an active infection or history of infections as follows:

• - a serious infection, defined as requiring hospitalization or intravenous anti-infectives within 8 weeks prior to the first IMP dose of the extension study, with the last dose having been received within 7 days of start of the extension study, - 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 extension study to be detrimental to the subject.

7. Major chronic inflammatory or connective tissue disease other than PsA or AS/nr axSpA (e.g., rheumatoid arthritis, systemic lupus erythematosus, Lyme disease, and gout). 8. Known diagnosis of fibromyalgia, regional pain syndromes or active uveitis/symptomatic inflammatory bowel disease requiring therapy (AS/nr-axSpA subjects), 9. Subject has any concurrent medical condition or uncontrolled, clinically significant systemic disease (e.g., renal failure, heart failure, hypertension, liver disease, diabetes, or anaemia) that, in the opinion of the Investigator, could cause continued treatment to be detrimental to the subject. 10. Subject has a known history of infection with hepatitis B, hepatitis C, or human immunodeficiency virus during the parent study. 11. Subject had a myocardial infarction, unstable angina pectoris, or ischemic stroke within the past 6 months prior to the first IMP dose for this extension study. 12. Subject has any active malignancy, including evidence of cutaneous basal or squamous cell carcinoma or melanoma. 13. Subject has a history of malignancy EXCEPT treated and considered cured cutaneous basal or squamous cell carcinoma, in situ cervical carcinoma, OR in situ breast ductal carcinoma. 14. Subjects with a history of alcohol or drug abuse during the parent study. 15. Significant risk of suicidality at the Baseline assessment of this extension study based on the Investigator's judgment or, if appropriate, as indicated by a response of "yes" since the last visit to question 4 or 5 in the suicidal section, or any response in the behavioral section of the Columbia-Suicide Severity Rating Scale (C SSRS). 16. Subject has a need for use of a live vaccine within 10 weeks of final anticipated dose of IMP for the long-term extension study. 17. Concomitant use of prohibited medications or use of commercially available or investigational biologic therapies (other than tildrakizumab) for psoriasis, PsA, and/or AS/nr axSpA. General: 18. Subjects who have been placed in an institution on official or judicial orders. 19. Subjects who are related to or dependent on the Investigator, Sponsor, or study site such that a conflict of interest may arise.