SAT0568 PERSISTENT VASCULAR 18F-FDG UPTAKE DESPITE CLINICAL-ANALYTICAL REMISSION IN PATIENTS WITH LARGE VESSEL VASCULITIS UNDER TOCILIZUMAB THERAPY. SINGLE UNIVERSITARY CENTER EXPERIENCE OF 30 PATIENTS.
Authors: D. Prieto-Peña, M. Calderón-Goercke, I. Martínez-Rodríguez, J. I. Banzo, J. García-Fernández, P. Vicente-Gómez, M. A. González-Gay, R. Blanco
Journal: Annals of the Rheumatic Diseases (2020)

Background: Tocilizumab (TCZ) has shown efficacy in large vessel vasculitis (LVV) (1-3 ). Disease activity assessed by laboratory markers (ESR,CRP) may be of less value with TCZ. 18 F-FDG PET/CT may be useful to monitor LVV disease activity (4-5 ). Objectives: To assess a ) evolution of disease activity in LVV treated with TCZ by PET/CT and b ) its correlation with clinical/serological markers. Methods: Single centre study of 30 patients with refractory LVV treated with TCZ who had a baseline and follow-up PET/CT scan. Vascular uptake was assessed quantitatively and qualitatively. Quantitative analysis was assessed as a target to background ratio (TBR)=SUVmax thoracic aorta/SUVmax aortic vascular pool. For qualitative analysis, FDG uptake at vessel wall was visually grading compared to the liver. We defined a total vascular score which included 5 vascular areas (supra aortic trunks, thoracic, abdominal, iliac and femorotibial arteries) ranging from 0 to 15. Clinical improvement (no improvement/partial/complete), analytical (CRP mg/dL; ESR mm/1 st hour) and reduction of prednisone dose (mg/day) were also assessed. Results: 30 patients (24 w/6 m); mean age 65.3 ± 10.6 yrs. TCZ was started after 6.5 [2.0-20.0] months from LVV diagnosis. Most patients received TCZ as intravenous infusions (70%) and almost half of them (46.7%) received combined therapy with MTX. Clinical/analytical evolution and quantitative/qualitative uptake assessment is shown in TABLE . After a mean follow-up of 37.0±18.5 months, 92.3% of patients experienced complete clinical/analytical improvement. Complete quantitative normalization of vascular uptake (TBR&lt; 1.34) was achieved in 30.8%. Qualitatively, 23.1% of patients showed normalization (total vascular score =0) at the end of the study period. Conclusion: Most patients with LVV under TCZ experienced rapid and effective clinical and analytical response. Decrease of vascular uptake was also observed both quantitatively and qualitatively assessed. However, complete normalization of vascular uptake despite clinical remision was only observed in less than one-third of patients. TABLE. Basal (n=30 ) 6 months (n=9 ) 12-18 months (n=21 ) &gt;18 months (n=13 ) Clinical improvement Complete, n (% ) 7 (77.8) 16 (76.2) 12 (92.3) Laboratory markers ESR (mm/1sth), median [IQR] 24.0 [9.8-53.0] 2.0 [2.0-3.0] * 2.0 [2.0-4.0] * 2.0[2.0-3.5] * CRP (mg/dL), median [IQR] 1.5 [0.5-2.4] 0.1 [0.1-0.2] * 0.1 [0.1-0.1] * 0.1 [0.1-0.1] * ESR/CRP normalization, n (% ) 9 (100) 21 (100) 13 (100) FDG vascular uptake TBR, mean ± SD 1.69 ± 0.52 1.56±0.41 * 1.46±0.16 * 1.40 ± 0.18 * Total vascular score, mean ± SD 5.0 ± 2.6 3.7 ± 2.2 3.3 ± 1.7* 2.7 ± 2.4* Quantitative normalization, n (% ) 4 (44.4) 5 (23.8) 4 (30.8) Qualitative normalization, n (% ) 1 (11.1) 1 (4.8) 3 (23.1) *test Wilcoxon: p &lt; 0.05. Quantitative normalization when TBR &lt;1.34. Qualitative normalization when total vascular score =0. References: [1]Calderón-Goercke M et al. Tocilizumab in giant cell arteritis. Observational, open-label multicenter study of 134 patients in clinical practice. Semin Arthritis Rheum. 2019 Aug; 49(1):126-135. doi: 10.1016/j.semarthrit.2019.01.003. [2]Loricera et al. Tocilizumab in patients with Takayasu arteritis: a retrospective study and literature review. Clin Exp Rheumatol. 2016 May-Jun;34(3 Suppl 97): S44-53. [3]González-Gay MA et al. Current and emerging diagnosis tools and therapeutics for giant cell arteritis. Expert Rev Clin Immunol. 2018 Jul;14(7):593-605. doi: 10.1080/1744666X.2018.1485491. [4]Martínez-Rodríguez et al. (18)F-FDG PET/CT in the follow-up of large-vessel vasculitis: A study of 37 consecutive patients. Semin Arthritis Rheum.2018 Feb;47(4):530-537. doi: 10.1016/j.semarthrit.2017.08.009. [5]Loricera et al. Non-infectious aortitis: a report of 32 cases from a single tertiary centre in a 4-year period and literature review. Clin Exp Rheumatol. 2015 Mar-Apr; 33(2 Suppl 89): S-19-31. Disclosure of Interests: D. Prieto-Peña: None declared, Monica Calderón-Goercke: None declared, Isabel Martínez-Rodríguez: None declared, Jose Ignacio Banzo: None declared, Javier García-Fernández: None declared, Patricia Vicente-Gómez: None declared, Miguel A González-Gay Grant/research support from: Pfizer, Abbvie, MSD, Speakers bureau: Pfizer, Abbvie, MSD, Ricardo Blanco Grant/research support from: AbbVie, MSD, Roche, Consultant of: Abbvie, Eli Lilly, Pfizer, Roche, Bristol-Myers, Janssen, UCB Pharma and MSD, Speakers bureau: Abbvie, Eli Lilly, Pfizer, Roche, Bristol-Myers, Janssen, UCB Pharma. MSD