Background/Purpose: Large vessel vasculitis (LVV) with aorta involvement are often refractory to common immunosuppressive therapy. Due to the pathogenic role of IL-6 in, we prospectively treated 10 patients with anti-IL6 receptor monoclonal antibody, tocilizumab (TCZ). Efficacy was assessed by clinical and laboratory parameters and by ¹⁸F-fluorodeoxyglucose positron emission tomography ([¹⁸F]FDG-PET). 

Methods: 10 (9 women/1 men) patients with LVV diagnosed by [¹⁸F]FDG-PET imaging who were treated with intravenous TCZ at the dose of 8 mg/Kg/monthly. Prednisone (PDN) at stable dose of 10 mg/day or less was allowed and, based on clinical response, the drug was interrupted thereafter. At baseline and after 6 months of therapy, patients underwent [¹⁸F]FDG-PET imaging evaluation. Severity of large vessel inflammation was evaluated by using the standardized uptake value (SUV) of [¹⁸F]FDG accumulation and the SUVmax normalized for liver [¹⁸F]FDG uptake. Anova test was used for comparison between groups. C-Reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were measured. Pain visual analogue scale (VAS) was evaluated before and after treatment and correlated with percentage of SUVmax variation trough linear regression. SPSS was used for statistical analysis.

Results:

The mean age±SD was 59± 15 years. The underlying conditions were: Takayasu arteritis  (n=4 cases), giant cell arteritis (GCA) (n=4), and aortitis (n=2). TCZ was the first biologic drugs used in 5 cases (2 aortitis and 3 GCA).  In the remaining cases anti-TNF infliximab was prescribed before TCZ (infliximab at the dose of  5 mg/kg/iv/8 weeks/iv).

After 6 months of TCZ [¹⁸F]FDG-PET was repeated, at that time all patients experienced clinical improvement with a reduction of erythrocyte sedimentation rate (ESR) from 55 ± 27SD 1^st h to 14±14SD 1^sth and C-reactive protein from 5±4 SD mg/dl to 0.2±0.1SDmg/dl.

VAS pain improved form 9.03 ± 0.7 SD cm to 2.35± 1.15 SD cm

Before TCZ , 44% of patients had fever and 22% Polymialgia rheumatica who disappeared after 3 months of treatment.

SUVmax before TCZ was 2.83 ± 0.33 SD after TCZ was 2.08± 0,28  with p value= 0,0001. SUV max normalized for liver before TCZ was 1,24± 0.24  after TCZ was 0.87± 0.18 with p value=0,001.

The greatest percentage of SUVmax variation was correlated with the greatest percentage of VAS pain improvement with a statistical significant correlation of 0.0001. PDN interruption was possible in all patients after two infusions of TCZ.

Conclusion: TCZ appears to be effective in patients with large vessel vasculitis refractory to corticosteroids or to anti-TNF drugs. The well- known diagnostic value of [¹⁸F]FDG-PET is enriched by the quantitative evaluation of vessel inflammation that is fundamental for the treatment follow-up.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/tocilizumab-in-refractory-large-vessel-vasculitis-with-aorta-involvement-study-on-10-patients-evaluated-by-positron-emission-tomoghraphy/