Takayasu arteritis (TA) is a chronic inflammatory disease affecting large and medium caliber arteries, particularly the aortic arch and its main branches. Clinical manifestations are caused by the marked thickening of the wall of the involved vessels, resulting in lumen narrowing and ischemia of the tributary districts. Therapy is based on the use of corticosteroids, immunosuppressants, and biologic drugs including infliximab, a monoclonal antibody blocking tissue necrosis factor (TNF)-alpha. Biosimilar infliximab is commercially available and used in the treatment of various immune-mediated conditions. There are currently no data on the efficacy and safety of biosimilar infliximab in the treatment of TA.||The investigators propose this monocentric, observational, prospective, open label study to evaluate the efficacy and safety of biosimilar infliximab in the treatment of 30 patients with TA. Specifically, the study will include: I) TA patients refractory to treatment with corticosteroid and/or immmunosuppressive therapy, not previously treated with infliximab; II) TA patients already receiving treatment with originator infliximab.||Biosimilar infliximab will be administered at dosages usually employed in the treatment of TA. Specifically, patients not previously treated with the originator drug will receive biosimilar infliximab intravenously at a dose of 5 mg/Kg at time 0, at week 2, at week 4; thereafter, treatment will be administered every 4-6 weeks at a dose of 5-10 mg/kg based on clinical judgement. In patients previously treated with the originator drug, biosimilar infliximab will be administered at the same dosages.||To evaluate the efficacy of therapy, changes in clinical manifestations, laboratory examinations, and imaging findings including angio-magnetic resonance imaging (MRI) of thoracic and abdominal vessels and total body PET/CT scan will be evaluate at time 0 as well as 6 and 12 months following treatment initiation. In order to evaluate the safety of the study treatment, the investigators will stringently evaluate possible side effects of treatment, including infusion reactions, changes in laboratory tests, infection, cancer, autoimmune manifestations, neurological and cardiovascular symptoms.||The total duration of follow up for each patient will be 52 weeks from enrolment.