Testing ixekizumab in adults with psoriatic arthritis not helped by prior treatment

Who can take part

• Confirmed diagnosis of PsA, according to an expert physician, and fulfilling the Classification Criteria for Psoriatic Arthritis (CASPAR) criteria (55); 2. Age greater than or equal to 18 years; 3. Active disease (defined as 3 or more swollen joints AND 3 or more tender joints); 4. Potential indication to (new) bDMARD therapy with IXE according to treating physician opinion, in line with international and national recommendations (3,57) and product data sheet; 5. Patients refractory to previous (at least 1) csDMARDs therapies (incomplete response, loss of efficacy or adverse events), naïve to b/tsDMARDs; 6. One of the involved joints has to be appropriate for US-guided synovial biopsy; 7. Patients must provide written informed consent; 8. Oral prednisone at doses of ≤10 mg/day (stable for at least 4 weeks); 9. No concomitant csDMARDs or concomitant background csDMARDs stable for at least 4 weeks

Who cannot take part

• Contraindication to start a new bDMARD treatment course; 2. Previous treatment with bDMARDs (any, included anti-IL17A agents) or tsDMARDs (any); 3. Contraindication to US-guided synovial biopsy (e.g. uncontrolled haemostatic disorders, allergies to local anaesthetics); 4. Previous treatment with intra-articular steroids within the previous 1 month; 5. Patients with dementia or an altered mental status, which would preclude the understanding and rendering of informed consent; 6. Known allergy or hypersensitivity to any biologic therapy; 7. Administration of live attenuated vaccine(s) (LAVs) within 6 weeks of enrolment. Or intended use of LAV during the treatment period; 8. Any history of malignancy in the last 5 years except for completely resected squamous or basal cell carcinoma of the skin; 9. For women of childbearing potential: Positive pregnancy test, presently breast-feeding, or unwillingness to use effective contraceptive measures for the duration of the study and 3- months after study completion; 10. Known immunodeficiency or patients immunocompromised to an extent that participation in the study would pose and unacceptable risk to the patient; 11. Clinically relevant (chronic or acute) infections, including untreated (latent) tuberculosis, hepatitis B or C or HIV infections; 12. Subjects with other autoimmune disease, e.g. Crohn's disease, Ulcerative colitis and Graves disease, except celiac disease and hypothyroidism which do not need to be excluded