BackgroundLarge vessel involvement in Giant Cell Arteritis (GCA), especially the aorta and/or its main branches, is frequent. Tocilizumab (TCZ) has shown efficacy and safety in GCA and other large-vessel vasculitis (1-4).ObjectivesTo assess the efficacy and safety of TCZ in GCA patients with involvement of the aorta and/or its main branches.MethodsMulticenter observational study of 196 patients with GCA and involvement of the aorta and/or its major branches treated with TCZ. GCA was diagnosed by: a) ACR criteria, and/or b) temporal artery biopsy, and/or c) imaging techniques. The presence of aortitis was performed by imaging techniques, mainly PET, and A-MRI.Maintained remission was considered according to EULAR definitions (5).ResultsThe main features of the 196 patients are showed in Table 1. Polymyalgia rheumatica, constitutional syndrome and headache were the most frequent clinical manifestations at TCZ onset. At 6 months after starting TCZ, 20% of the patients reached a sustained remission, that was progressively increasing. (Figure 1). A corticosteroid-sparing effect was observed from month 1 of TCZ onset (Figure 1). Relevant adverse events were observed in 12 per 100 patients-year, documenting serious infections in 4.8 per 100 patients-year (Table 1).Table 1.Main features of 196 GCA patients with involvement of the aorta and/or its main branches treated with TCZ.GCA (n=196)Features at TCZ onsetAge(years), mean±SD71.3±9.5Sex, female/male (% female)148/48 (75)Time from GCA diagnosis to TCZ onset (months), median [IQR]7 [2-18.25]Systemic manifestations, n (%)Fever, n (%)24 (12)Constitutional syndrome, n (%)87 (44)PmR, n (%)131 (67)Ischaemic manifestations, n (%)Visual involvement, n (%)16 (8)Headache, n (%)74 (38)Jaw claudication, n (%)27 (14)Laboratory dataESR, mm 1st hour, median [IQR]32 [14-54]CRP, mg/dL, median [IQR]1.5 [0.6-3.2]Prednisone dose, mg/day, median [IQR]15 [10-30]Safety after TCZ onsetRelevant adverse events, per 100 patients-year12Serious infections, per 100 patients-year4.8Figure 1.A) Sustained remission, and B) median prednisone dose required in GCA patients with aortitis treated with tocilizumabConclusionTCZ seems to be effective and relatively safe in GCA patients with involvement of the aorta and/or its main branches.References[1]Calderón-Goercke M, et al. Semin Arthritis Rheum. 2019; 49: 126-135. PMID: 30655091[2]Loricera J, et al. Clin Exp Rheumatol. 2016; 34: S44-53. PMID: 27050507[3]Loricera J, et al. Clin Exp Rheumatol. 2015; 33: S19-31. PMID: 25437450[4]Prieto-Peña D, et al. Ther Adv Musculoskelet Dis. 2021; 13: 1759720X211020917. PMID: 34211589[5]Hellmich B, et al. Ann Rheum Dis. 2020; 79: 19-30. PMID: 31270110Disclosure of InterestsLara Sanchez-Bilbao: None declared, Javier Loricera Speakers bureau: from Roche, Novartis, UCB Pharma, Celgene, and Grünenthal., Rafael Melero: None declared, Santos Castañeda Speakers bureau: UAM-Roche, EPID- Future chair, Department of Medicine, Universidad Autónoma de Madrid, Madrid, Spain., Clara Moriano: None declared, Iván Ferraz-Amaro: None declared, J. Narváez: None declared, Vicente Aldasoro: None declared, Olga Maiz: None declared, Ignacio Villa-Blanco: None declared, Paloma Vela-Casasempere: None declared, Susana Romero-Yuste: None declared, Jose Luis Callejas-Rubio: None declared, Eugenio de Miguel: None declared, E. Galíndez-Agirregoikoa: None declared, Francisca Sivera: None declared, Carlos Fernández-López: None declared, Carles Galisteo: None declared, Julio Sanchez-Martin: None declared, Monica Calderón-Goercke: None declared, J. Luis Hernández: None declared, Miguel A González-Gay Speakers bureau: Abbvie, Pfizer, Roche, Sanofi, Lilly, Celgene, and MSD., Grant/research support from: AbbVie, MSD, Jansen, and Roche,, Ricardo Blanco Speakers bureau: Abbvie, Pfizer, Roche, Bristol-Myers, Lilly, Janssen, and MSD., Grant/research support from: Abbvie, MSD, and Roche