Evaluation of Tocilizumab as an add-on Therapy to Corticoids in Giant Cell Arteritis: Proof of Concept Study.

Inclusion Criteria:

• Age > 50 years

• GCA fulfilling ≥3/5 ACR criteria

• Newly diagnosed GCA or relapsing GCA if treatments (Glucocorticoids±immunosuppressants) have been stopped for at least 6 months

• Glucocorticoids started for less than 21 days

• Proof of large vessel vasculitis:

• Positive temporal artery biopsy (TAB)

• Aortitis, as defined by regular circumferential wall thickening ≥3mm in theabsence of calcification and/or significant atheroma on angio-CT images; or ahomogeneous vascular signal more intense than the liver on 18FDG-PET images.

• For men and women of a child-bearing age, an effective method of contraception must beused by the patient or his or her partner throughout the treatment with tocilizumab (or placebo) and for 3 months after the end of the treatment. Breast-feeding is notauthorised until 3 months after the end of treatment with tocilizumab. Women notconsidered at risk of pregnancy are those defined by menopause of at least one year orsurgically steriles (ligature of the fallopian tubes, bilateral ovariectomy orhysterectomy)

• Persons who have provided written informed consent

• Persons covered by the National Health Insurance Agency

Exclusion Criteria:

• Pregnancy

• hospitalization in the previous year for drug or alcohol intoxication

• current treatment for another autoimmune or inflammatory disease

• known hypersensitivity to TCZ or one of its excipients or another human or murinemonoclonal antibody

• treatment with anti-TNF-α, methotrexate, cyclophosphamide, dapsone, methylprednisolonepulses or any other immunosuppressive or immunomodulatory drug or biotherapy within 6months before inclusion

• long-course systemic GC therapy

• prednisone therapy >1 mg/kg/day, whatever the duration

• serious or chronic proven infections requiring hospitalization or intravenousantibiotics within 30 days before inclusion

• other proven infections that required antibiotics within 14 days before inclusion

• opportunistic infections

• evidence of active tuberculosis or latent tuberculosis (as defined by a positiveinterferon gamma release assay)

• active chronic hepatitis B or C or HIV

• cancer or lymphoproliferative disorders within the 5 years before inclusion (with theexception of in situ cervical cancer and squamous or basal cell carcinoma with R0resection)

• past history of sigmoid diverticulitis

• any active hepatic disease

• hepatic failure; thrombocytopenia <50 G/L

• neutropenia <0.5 G/L

• history of moderate to severe congestive heart failure or demyelinating disease

• recent stroke

• current signs or symptoms of severe, progressive, or uncontrolled disease, not due toGCA, which contraindicates TCZ

• severe and uncontrolled hypercholesterolemia

• high cardiovascular risk (former cerebral or coronary vascular event, or vascular risk >20% at 10 years according to the Framingham risk score [24]); dementia; non-compliantpatients

• patients under ward of court, tutelage or legal guardianship.