Background:Behcet’s disease (BD) is a chronic and relapsing vasculitis, in which major vessel involvement is a main cause of mortality and morbidity. The therapeutic arsenal is mainly composed of classical immunosuppressants. However, when faced with resistance to these drugs, no alternative therapeutic strategy is currently recommended.Objectives:To assess the efficacy and safety of interleukin 6 receptor inhibitor tocilizumab (TCZ) in refractory arterial involvement of BD in a real-life observational setting.Methods:10 patients were enrolled in our center between 2014 and 2019. All patients met the international criteria for BD and had severe arterial involvement evaluated by echocardiography, angio-Computerized Tomography scan and vascular Doppler. The diagnosis of refractory arterio-BD was based on objective vascular symptoms not explained by any other known disease and non-response to conventional immunosuppressants combined with glucocorticoids therapy. All patients underwent TCZ infusions at 8mg/kg every 4 weeks. Concomitant therapy with immunosuppressants and glucocorticoids was continued. Clinical and imaging findings were assessed before and after TCZ therapy. All adverse events were recorded during follow-up.Results:All the patients were males, with a mean age of 44.3±10.5 years in this study. The mean age at presentation of arterial involvement was 40.8±9.2 years old. The patterns of arterial involvement were aneurysm (n=9), stenosis (n=3) and aortic valve lesion (n=2). After a mean follow-up of 26.8±7.2 months, TCZ yielded rapid and maintained clinical improvement in 9 patients, with complete remission in 6 of them and partial response in 3 of them. Discontinuation of TCZ treatment due to relapse occurred in one case as the enlargement of abdominal aortic aneurysm. The mean glucocorticoid dosage was tapered from 54.5±20.6mg/d to 8.3±3.6mg/d (pConclusion:TCZ was a safe and effective therapeutic option for refractory arterial involvement of BD, with a favorable steroid-sparing effect.References:[1]G Hatemi, R Christensen, D Bang, et al. 2018 update of the EULAR recommendations for the management of Behçet’s syndrome. Ann Rheum Dis. 2018;77(6):808-818.[2]Y Ozguler, P Leccese, R Christensen, et al. Management of major organ involvement of Behcet’s syndrome: a systematic review for update of the EULAR recommendations. Rheumatology (Oxford). 2018;57(12):2200-2212.[3]M Akiyama, Y Kaneko, T Takeuchi. Effectiveness of tocilizumab in Behcet’s disease: A systematic literature review. Semin Arthritis Rheum. 2020;50(4):797-804.Table 1.Tocilizumab therapy in ten cases of refractory arterio-BDPatientAge, yearDisease duration, monthsClinical features*Arterial lesionsPrevious therapyResponse at week 24134228O, G, P, S, IStenosis of CA/ SMA/RA/SCA, aortic valve prolapsePred/CYC/MMFCR22024O, SDissecting aneurysm of AA (Debakey I)Pred/MMFPR367276O, G, P, S, Athoracoabdominal aortic aneurysmPred/CYC/TACCR46775O, S, UStenosis of LAD/LCX/RCAPred /CYCCR55080O, G, AAbdominal and coronary aortic aneurysmsPred /CYCRelapse64826O, GAortic insufficiencyPred /CYCPR726147O, P, S, VIliac artery aneurysmPred /MMFCR849466O, S, VThoracoabdominal and coronary aortic aneurysmsPred /CYC/AZACR927181O, P, SPseudoaneurysm of CCAPred /CYCPR10Male/55354O, P, SAbdominal aneurysm, stenosis of LAD/LCX/RCAPred /CYC/AZACR*O: oral ulcer; G: genital ulcer; P: pathergy test; S: skin lesions; I: intestinal ulcer; A: arthritis; U: uveitis; V: venous thrombosisFigure 1.Changes from baseline in BSAS, BDCAF, ESR, CRP and steroid daily dose at 24 weeksDisclosure of Interests:None declared