Date: Monday, November 9, 2020
Session Type: Poster Session D
Session Time: 9:00AM-11:00AM
Background/Purpose: Tocilizumab (TCZ) has shown efficacy in large vessel vasculitis (LVV)-giant cell arteritis (LVV-GCA). Disease activity in LVV assessed by laboratory parameters (ESR, CRP) may be of less value with TCZ. Imaging assessment by 18F-fluodeoxyglucose positron emission tomography (18F-FDG PET/CT) may be useful to monitor LVV disease activity.
Our aim was to determine if clinical improvement correlated with decrease of vascular uptake in follow-up PET/CT scans.
Methods: Single center study of patients with refractory LVV-GCA treated with TCZ who had a baseline and follow-up PET/CT scan. For the visual analysis, FDG uptake at the thoracic aorta wall was visually grading compared to the liver uptake (0: no uptake, 1: less than liver, 2: equal to liver, 3: uptake greater than liver uptake). We defined a total vascular score (TVS) which included 5 vascular regions (supra aortic trunks, thoracic aorta, abdominal aorta, iliac arteries, femorotibial arteries) ranging from 0 to 15. Besides, a semiquantitative analysis was performed as a target to background ratio (TBR)= SUVmax thoracic aorta wall/SUVmax aortic vascular pool. The baseline and follow-up TVS and TBR were compared. Clinical and analytical improvement and and reduction of prednisone dose (mg/day) were also assessed.
Results: We included 30 patients (24 women/6 men); mean age 65.7± 9.8 years. Baseline PET/CT scans were performed due to active disease at a median [interquartile range-IQR] of 1.5 [0.0-4.0] months before TCZ onset. Following TCZ therapy, 25 (83.33%) patients achieved clinical remission and reduction of FDG vascular uptake was also observed after a mean of 10.8±3.7 months. TBR decreased from 1.70 ± 0.52 to 1.48 ± 0.25 (p=0.005) and TVS from 4.97±2.62 to 3.13±1.89 (p< 0.001). However, only 9 (30%) patients showed complete normalization of TBR and only 3 (10%) normalization of TVS (TABLE).
Conclusion: Most of patients with LVV under TCZ therapy experienced a rapid and effective clinical and analytical improvement. However, less than one-third show normalization of 18F-FDG vascular uptake.
To cite this abstract in AMA style:Sanchez-Bilbao L, Prieto-Peña D, Gonzalez-Mazon I, Martinez-Lopez D, Calderon-Goercke M, Martínez-Rodríguez I, Banzo I, González-Gay M, Blanco R. Ongoing Vascular 18F-FDG Uptake Despite Clinical Remission in Patients Receiving Tocilizumab for Large Vessel Vasculitis-Giant Cell Arteritis: Single Universitary Center Experience of 30 Patients [abstract]. Arthritis Rheumatol. 2020; 72 (suppl 10). https://acrabstracts.org/abstract/ongoing-vascular-18f-fdg-uptake-despite-clinical-remission-in-patients-receiving-tocilizumab-for-large-vessel-vasculitis-giant-cell-arteritis-single-universitary-center-experience-of-30-patients/. Accessed April 13, 2021.
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