Efficacy of Tocilizumab in Primary Sjögren's Syndrome.

Inclusion Criteria : * Patient with primary Sjögren's syndrome according to the European - American consensus group criteria. * ESSDAI score ≥ 5. * In women in childbearing age, effective contraception during treatment and 3 months following treatment discontinuation. Exclusion Criteria: * Patient with previous history of therapy with tocilizumab. * Prednisone treatment introduced two weeks before inclusion or a change in this drug dose within two weeks before inclusion. * A prednisone dose ≥ 15 mg per day. * Non-steroidal anti-inflammatory drugs, pilocarpine hydrochloride, cyclosporine, cimeviline if introduced within two weeks before inclusion. * Therapy with methotrexate, Hydroxychloroquine, chloroquine, quinacrine, leflunomide, psychoactive drug if introduced within 8 weeks before inclusion or a dose change within 8 weeks before inclusion. * Treatment with azathioprine or mycophenolate mofetil within 8 weeks before inclusion. * Live and live attenuated vaccines given within 4 weeks before inclusion. * Any biologic treatment within 6 month before inclusion. * Treatment with cyclophosphamide, intravenous immunoglobulin therapy or plasmapharese therapy in the last 6 months before inclusion. * Systemic auto-immune disease. * Patient with previous history of diverticular perforations, complications of diverticulitis, peritonite or inflammatory bowel disease (such as Crohn's disease and Colitis ulcerative). * Patient with history of severe infection within 4 weeks before inclusion. * Patient with history of infection within 2 weeks before inclusion. * Patient with chronic infection or infection returns (e.g. tuberculose, VHB, VHC…). * Positive serology tests for HIV, HBV, HCV. * Severe uncontrolled dyslipidemia. * Hepatocellular insufficiency. * Unstable cardiovascular disease. * Severe or chronic kidney disease, severe or chronic lung disease, severe or chronic endocrine disorder, severe or chronic neurological disease ( not related to the SJP). * Patient with history of solid organ transplantation or haematopoietic stem cell transplantation. * Patient with history of lymphoma, neoplasia diagnosed 5 years before inclusion except squamous and basal cell cancers and carcinoma in situ of the uterine cervix. * Severe complications of SJp at the inclusion: vasculitis with renal neurologic, digestive or cardiac involvement, interstitial lung disease, symptomatic cryoglobulinemia with severe neurologic involvement, renal function impairment, severe myositis, corticotherapy ≥ 1 mg/kg in the last 30 days before inclusion. * Neutropenia \< 1000\*10\^6 . * Thrombocytopenia \< 50 000/µl * ALT or AST \> 3 x ULN * alcohol and drug addiction : withdrawal at least one year before inclusion * A major surgical procedure in the 8 weeks before inclusion or a scheduled major surgery * Pregnant woman, breast feeding woman * Adults under supervision or guardianship * Patient taking part in another clinical trial