Op0269 Treatment of Giant Cell Arteritis With Ultra-Short Glucocorticoids and Tocilizumab: Results From the Extension to 76 Weeks

Background: The mainstay of treatment of giant cell arteritis (GCA) still relies on high doses and prolonged glucocorticoid (GCs) courses. Previous studies assessed the efficacy and safety of one year of TCZ monotherapy after 3 boluses of intravenous methylprednisone in inducing remission in patients with GCA and large vessel involvement1. Objectives: To assess the maintenance of efficacy of TCZ montherapy and the proportion of patients with new aortic dilation over a six-month observation period after the withdrawal of TCZ. Methods: 18 patients were previously treated with 3 boluses of intravenous methylprednisone and weekly subcutaneous TCZ in monotherapy for 52 weeks thereafter. Patients who completed the 52-week part and were in clinical remission stopped TCZ and were eligible to enter the second part, a 24-week observational follow-up. Clinical assessment was performed every 12 weeks, and positron emission tomography/computed tomography (PET/CT) was repeated at week 76. The PET Vascular Activity Score (PETVAS) and the diameters of the aorta at 4 different levels (ascending aorta, descending thoracic aorta, suprarenal, and infrarenal abdominal aorta) were calculated by a single nuclear medicine physician and a radiologist. Clinical remission was defined by the absence of any clinical signs and symptoms directly attributable to GCA, including normalization of the acute phase reactants, independently by imaging evaluation. Aortic dilation was defined by a diameter >40 mm in the ascending aorta, ≥40 mm in the thoracic descending aorta, and ≥30 mm in the abdominal aorta. The primary endpoint was the maintenance of efficacy assessed on PET/CT as the variation of PETVAS at week 76 compared with baseline and week 52 and as the proportion of patients with clinical remission at week 76. The secondary endpoint was the proportion of patients with new aortic dilation at week 76. Results: 13 patients were in clinical remission at week 52 stopped TCZ and entered in the 6 months follow-up period without any treatment. 2 patients relapsed 8 and 22 weeks after TCZ suspension, respectively. 11 PET/CT were performed at week 76. Compared to the baseline value, a significant reduction of PETVAS was observed at week 76 (mean reduction -6.6, p =0.004). However, after suspension of TCZ, a significant increase of PETVAS was observed at week 76 compared to week 52, (mean increase 4.6, p =0.016) (Table 1). 4 of the 11 PET/CT (36%) were considered active by nuclear medicine physician's interpretation. The proportion of patients with clinical remission at week 76 was 85% (95% CI 55-98) (Table 1). At week 76, one patient showed a new aortic dilation (Table 1). 2 patients who presented an aortic dilation at week 52 were in clinical remission at weeks 52 and 76. Still, both showed further aortic dilation at CT performed at week 76. Conclusion: One year of TCZ monotherapy was able to maintain sustained clinical remission in a sizeable proportion of patients with GCA. However, after the withdrawal of TCZ, there was a significant increase in the fuoredoxyglucose (FDG) uptake and a new aortic dilation. Whether this persistence of activity despite clinical remission may indicate future relapses is still unknown. REFERENCES: 1 Muratore F, et al. Rheumatology (Oxford). 2023 May 17:kead215. Table 1. Clinical Outcomes Acknowledgements: NIL. Disclosure of Interests: None declared.