Inclusion Criteria:  Male or non-pregnant, non-nursing female >18 years of age at screening Patients with a diagnosis of axSpA who fulfil the diagnostic Assessment of SpondyloArthritis International Society (ASAS) criteria for axSpA Stable medical treatment with TNFi the last 6 months Low disease activity (ASDAS<2.1) at inclusion Capable of understanding the Norwegian language and of signing an informed consent form  Exclusion Criteria:  Medical conditions:  Major co-morbidities, such as severe malignancies, severe diabetes mellitus, severe infections, uncontrollable hypertension, severe cardiovascular disease (NYHA class III or IV), severe respiratory diseases, and/or cirrhosis. Indications of active tuberculosis (TB)  Diagnostic assessments:  Abnormal renal function, defined as serum creatinine >142 µmol/L in female and >168 µmol/L in male, or glomerular filtration rate (GFR) <40 mL/min/1.73 m2 Abnormal liver function (defined as Alanine Transaminase (ALT) >3x upper normal limit), active or recent hepatitis Leukopenia and/or thrombocytopenia  Other:  Pregnancy and/or breastfeeding (current at screening or planned within the duration of the study) Severe psychiatric or mental disorders, alcohol abuse or other substance abuse, language barriers or other factors which makes adherence to the study protocol impossible