<h3>Background:</h3> Patients with giant cell arteritis (GCA) can relapse despite treatment with glucocorticoids, methotrexate (MTX) and tocilizumab (TCZ). The JAK/STAT signalling pathway is involved in the pathogenesis of GCA, and JAK inhibitors (JAKi) are a potential therapeutic alternative. <h3>Objectives:</h3> We aimed to evaluate the effectiveness and safety of JAKi in patients with GCA. <h3>Methods:</h3> Retrospective study of GCA patients treated with JAKi in routine clinical practice. The clinical outcomes were clinical remission, defined as the absence of signs and symptoms attributable to GCA regardless of ESR and CRP values, and complete remission, defined according to EULAR criteria as the absence of signs and symptoms attributable to GCA along with the presence of normal ESR and CRP values[1]. Safety was also evaluated. <h3>Results:</h3> Overall, 35 patients (30 women [86%]; mean age, 72.3 years; relapsing disease 35 [100%]) received JAKi including baricitinib (n=15), tofacitinib (n=10) and upadacitinib (n=10). A total of 22 (63%) and 26 (74%) patients failed treatment with MTX and TCZ, respectively, before JAKi initiation. Other patient's features are listed in the <b>Table 1</b>. Clinical remission was observed at month 1, 3, 6 and 12 after JAKi initiation in 18/35 (51%), 18/33 (54%), 17/28 (61%) and 14/20 (70%) patients, respectively. The daily dose of prednisone decreased from 16.2 [8.7-30] at baseline to 5 [0-12.5] mg at last visit. Corresponding complete remission rates were 15/35 (43%), 16/33 (48%), 16/28 (57%) and 13/20 (65%) (<b>Figure 1</b>). Adverse events were reported in 5 (14%) patients: urinary tract infection (n=1), elevation of liver enzymes (n=1), palpitations and dyspnea (n=1), herpes zoster (n=1), and glioblastoma multiforme (n=1). <h3>Conclusion:</h3> This analysis of real-world data suggests that JAKi could be effective in GCA, even in patients who fail standard of care options. Results should be confirmed in randomized controlled studies. <h3>REFERENCES:</h3> [1] Dejaco C, et al. Ann Rheum Dis. 2023. PMID: 36828585. <b>Table 1.</b> Main features of the 35 GCA patients at JAKi initiation. <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> Fernando López-Gutiérrez Abbvie, Roche, Novartis, MSD, UCB Pharma, Celgene, Lilly, Pfizer, Galápagos, Javier Loricera Roche, Galápagos, Novartis, UCB Pharma, MSD, Celgene, Astra Zeneca, and Grünenthal, Janssen, Abbvie, Roche, Novartis, MSD, UCB Pharma, Celgene, Lilly, Pfizer, Galápagos, Toluwalase Tofade: None declared, Diana Prieto-Peña: None declared, Susana Romero-Yuste Abbvie, Astra-Zeneca, Bristol, Janssen, Lilly, Roche, Sandoz, Sanofi, UCB, Eugenio De Miguel Abbvie, Novartis, Pfizer, Roche, Janssen, Lilly, MSD, BMS, UCB, Grunental and Sanofi, Eztizen Labrador-Sánchez: None declared, Anne Riveros-Frutos Abbvie, Astra-Zeneca, Bristol, Janssen, Lilly, Roche, Sandoz, Sanofi, UCB, Iván Ferraz- Amaro Abbvie, Pfizer, Roche, Sanofi, Celgene, and MSD, Abbvie, MSD, Janssen, and Roche, Olga Maiz: None declared, Elena Becerra-Fernández: None declared, Javier Narváez: None declared, Eva Galíndez-Agirregoikoa: None declared, Ismael González: None declared, Angel Ramos Calvo: None declared, Ana Urruticoechea-Arana: None declared, Santos Castañeda assistant professor of the cátedra EPID-Future, funded by UAM-Roche, Universidad Autónoma de Madrid (UAM), Spain, BMS, Eli-Lilly, Roche, Gedeon-Richter, Grünenthal Pharma and UCB, MSD and Pfizer, Sebastian Unizony: None declared, Ricardo Blanco AbbVie, Pfizer, Roche, Bristol-Myers, Lilly, Galapagos, Novartis, Janssen, GSK, UCB, and MSD., AbbVie, Pfizer, Roche, Lilly, Janssen.

POS0077 EFFECTIVENESS OF JANUS KINASE INHIBITORS IN RELAPSING GIANT CELL ARTERITIS IN REAL-WORLD CLINICAL PRACTICE AND REVIEW OF THE LITERATURE