The primary endpoint is the proportion of patients in sustained remission until week 28 in the secukinumab group compared to the proportion of patients in the placebo group. to biological therapy and have newly diagnosed or relapsing GCA. Fifty patients are randomly assigned in a 1:1 ratio to receive either 300 mg secukinumab or placebo subcutaneously at baseline, weeks 1, 2 and 3, and every 4 weeks from week 4. Patients in both treatment arms receive a 26-week prednisolone taper regimen. The study consists of a maximum 6-week screening period, a 52-week treatment period (including the 26-week tapering), and an 8-week safety follow-up, with primary and secondary endpoint assessments at week 28. Patients who do not achieve remission by week 12 experience a flare after remission or cannot adhere to the prednisolone tapering will enter the Vancomycin escape arm and receive prednisolone at a dose determined by the investigators clinical judgment. The blinded treatment is usually continued. Two optional imaging sub-studies are included (ultrasound and contrast-media enhanced magnetic resonance angiography [MRA]) to assess vessel wall inflammation and occlusion before and after treatment. The primary endpoint is the proportion of patients in sustained remission until week 28 in the secukinumab group compared to the proportion of patients in the placebo group. A Bayesian approach is applied. Discussion The trial design allows the first placebo-controlled data collection around Vancomycin the efficacy and safety of secukinumab in patients with GCA. Trial registration ClinicalTrials.gov NCT03765788. Registration on 5 December 2018, prospective registration, EudraCT number 2018-002610-12; clinical trial protocol number CAIN457ADE11C. Keywords: Giant cell arteritis, Secukinumab, Phase II trial, Placebo, Double-blind Background Giant cell arteritis (GCA) is usually a systemic large vessel vasculitis affecting people aged 50 years and older. The two main types of large vessel vasculitis are Takayasu arteritis (TA) and GCA. Large vessel vasculitis covers the spectrum of primary vasculitis which leads to chronic granulomatous inflammation of larger arteries, e.g., temporal arteries, the aorta, or its major branches [1]. Up to 60% of patients with GCA also show features of polymyalgia rheumatica (PMR) which are overlapping inflammatory rheumatic disorders. Clinical signs and symptoms of PMR include stiffness and aching in the shoulder and pelvic girdles and cervical region. Conversely, 16C21% of patients with PMR have GCA [2]. GCA is the most common vasculitis in adulthood. Persons in Northern Europe hold the highest incidence of GCA and PMR, particularly persons of Scandinavian descent [3].The incidence of GCA in the USA is 18 per 100,000 which is the most frequent primary vasculitis. According to estimates, the number of GCA diagnoses will exceed 3 million cases by 2050 leaving approximately 500, 000 people visually impaired [4]. Typical clinical manifestations of GCA related to the inflammation of large- and medium-sized arteries are new-onset headaches, jaw claudication (cramping pain and/or fatigue felt in the jaw muscles during mastication), scalp tenderness, and visual disturbances. Characteristic systemic manifestations include fever, malaise, weight loss, and polymyalgia [5]. The most feared complication of GCA is usually irreversible, permanent visual loss representing a severe medical emergency. Therefore, prompt and effective immunosuppressive treatment is crucial in Vancomycin GCA [6, 7]. High-dose glucocorticoids are still the standard of care therapy and effectively reduce vascular inflammation [8, 9]. However, this treatment has serious disadvantages SIX3 for the patients: relapses and treatment failures are common, and more than 80% of patients suffer from serious adverse events (SAE) [8, 9]. In addition, many patients have relative contraindications to glucocorticoid therapy. Thus, there is an unmet need for glucocorticoid-sparing brokers, which allow for long-term remissions in the absence of those adverse effects associated with glucocorticoid treatment. Anti-tumor necrosis factor (TNF) inhibitors, azathioprine, and Vancomycin methotrexate could serve as potential alternatives, but treatment results are not conclusive [9C11]. Promising results came from the GiACTA-trial [12, 13]. In that trial, interference of interleukin-6 (IL-6) signaling with tocilizumab, an IL-6 receptor antagonist, had a beneficial effect in patients with GCA, which eventually led to the approval of tocilizumab for GCA. However, tocilizumab suppresses acute phase reactants, which are integral to currently used remission and relapse criteria. Reichenbach et al. analyzed magnetic resonance angiography (MRA) vessel wall indicators from a randomized controlled trial of tocilizumab.