Table 2 Eligibility criteria (selection)

► Diagnosis of GCA classified according to the following criteria:

• Age at onset of disease ≥ 50 years.

• History of ESR ≥ 30 mm/h or CRP ≥ 10 mg/L.

• Unequivocal cranial symptoms of GCA (new-onset localized headache, scalp or temporal artery tenderness, ischemia-related vision loss, or otherwise unexplained mouth of jaw pain upon mastication) AND/OR symptoms of PMR (defined as shoulder and/or hip girdle pain associated with inflammatory morning stiffness).

• Temporal artery biopsy revealing features of GCA AND/OR evidence of large-vessel vasculitis by angiography or cross-sectional imaging study such as MRA, positron emission tomography-computed tomography (PET-CT), or ultrasound.

► Patients with new onset GCA or relapsing GCA:

• Definition of new onset: diagnosis of GCA within 6 weeks prior to baseline visit.

• Definition of relapsing GCA: diagnosis of GCA (in accordance with inclusion criterion no. 4) > 6 weeks prior to baseline visit and in the meantime achieved remission (absence of signs and symptoms attributable to GCA and normalization of ESR [< 30 mm/h] and CRP [< 10 mg/L]) including previous treatment with ≥ 25 mg/day prednisolone equivalent for ≥ 2 weeks.

► Active disease as defined by the presence of signs and symptoms of GCA (cranial or PMR) and elevated ESR ≥ 30 mm/h, or CRP ≥ 10 mg/L, attributed to active GCA within 6 weeks of baseline.

► Prednisolone dose of 25–60 mg/day at baseline.

► Previous exposure to secukinumab or other biologic drug directly targeting IL-17 or IL17 receptor.

► Patients treated with any cell-depleting therapies including but not limited to anti-CD20 of investigational agents (e.g., anti-CD3, anti-CD4, anti-CD5 or anti-CD19).

► Patients who have previously been treated with any biologic agent including but not limited to tocilizumab, sirukinumab, abatacept, or TNF-alpha inhibitors (infliximab, adalimumab, etanercept, certolizumab, golimumab).

► Patients who have previously been treated with tofacitinib or baricitinib.

► Patients treated with intravenous immunoglobulins or plasmapheresis within 8 weeks prior to baseline.

► Patients treated with cyclophosphamide, tacrolimus or everolimus with 6 months prior to baseline.

► Patients treated with hydrochloroquine, cyclosporine A, azathioprine, sulfasalazine, mycophenolate mofetil within 4 weeks of baseline.

► Patients treated with leflunomide within 8 weeks of baseline unless a cholestyramine washout has been performed in which case the patient must be treated within 4 weeks of baseline.

► Patients treated with an alkylating agent.

► Patients requiring systemic chronic glucocorticoid therapy for any other reason than GCA.

► Chronic systemic glucocorticoid therapy over the last 4 years or longer, or inability, in the opinion of the investigator, to withdraw glucocorticoid therapy through protocol-defined taper regimen due to suspected or established adrenal insufficiency.

► Patients requiring chronic high potency opioid analgesics for pain management.

► Active ongoing inflammatory diseases or underlying metabolic, hematologic, renal, hepatic, pulmonary, neurologic, endocrine, cardiac, infectious or gastrointestinal conditions, which in the opinion of the investigator immunocompromises the patients and/or places the patients at unacceptable risk for participation in an immunomodulatory therapy.

► History of renal trauma, glomerulonephritis, or patients with one kidney only, or a serum creatinine level exceeding 1.8 mg/dL (159.12 μmol/L).

► Screening total white blood cell count < 3000/μl, or platelets < 100 000/μl, or neutrophils < 1500/μl, or hemoglobin < 8.3 g/dL (83 g/L).

► Major ischemic event, unrelated to GCA, with 12 weeks of screening.

► Known infection with human immunodeficiency virus, hepatitis B or hepatitis C at screening or randomization.

► Life vaccination within 6 weeks prior to baseline or planned vaccination during the study participation until 12 weeks after last study treatment administration.