This is a french multicenter observational study assessing safety and efficacy of biosimilar of Tocilizumab in Giant Cell Arteritis (GCA) with active aortitis, including 14 reference centers from the Groupe d'Etude Français des vascularites des gros vaisseaux (GEFA). Giant Cell Arteritis (GCA), formerly known as temporal arteritis, is the most common form of systemic vasculitis in patients aged ≥ 50 years. GCA is defined by granulomatous arteritis that affects large#sized and medium#sized blood vessels with a predisposition to affect the cranial arteries. Aortitis accounted for more than 50% of GCA patients with the new imaging techniques. Aortitis is typically diagnosed using imaging tests such as magnetic resonance imaging (MRI) or Computed Tomography (CT) scans. Aortitis is an inflammation of the aorta, leading to a range of symptoms such as fever, weight loss, fatigue, and chest pain. In severe cases, aortic aneurysms or aortic dissection can occur, which can be life-threatening. Multiple reports have demonstrated the presence of abnormal pro-inflammatory cytokine production in large-vessel vasculitis patients, particularly those with GCA, including interleukin-1 (IL-1), IL-6, IL-18, tumor necrosis factor-α (TNF-α), and interferon-γ, by T lymphocytes and macrophages. IL-6 has been implicated as a crucial cytokine in the pathogenesis of aortitis and targeting its signaling has shown promising results in treating the condition. IL-6 inhibitors such as tocilizumab have been found to effectively reduce disease activity and improve clinical outcomes in GCA patients. The GIACTA study (GiAnt cell arteritis roActemra (tocilizumab) study) was a randomized, double-blind, placebo-controlled trial that evaluated the efficacy and safety of tocilizumab in the treatment of GCA. The study included 251 patients with newly diagnosed or relapsing GCA and found that treatment with tocilizumab significantly increased the proportion of patients who achieved sustained remission from GCA at 52 weeks, compared to placebo. Additionally, tocilizumab was associated with a lower incidence of disease flares and a reduced need for glucocorticoid therapy. Following the positive results of the GIACTA study, tocilizumab was approved for the treatment of GCA in adults with active disease, including aortitis, who have not responded to glucocorticoids, or for whom glucocorticoid therapy is not appropriate, by regulatory agencies around the world, including the US Food and Drug Administration and the European Medicines Agency. However, the efficacy of IL-6 inhibitors on aorta inflammation as assessed by modern and powerful imaging techniques has never been specifically studied in GCA. This observational study will provide important informations on the impact of Tyenne® (tocilizumab) associated with short term low dose steroids on clinical manifestations and vessel inflammation and damage in aortitis of GCA.