Evaluation of tocilizumab for intractable Takayasu arteritis and 18F-fluorodeoxyglucose-positron emission tomography for detecting inflammation under tocilizumab treatment

Abstract

BackgroundAlthough high-dose glucocorticoids are effective in suppressing active inflammation of Takayasu arteritis (TAK), many patients experience relapse during tapering of glucocorticoids. Recently, the interleukin-6 receptor antibody, tocilizumab (TCZ), was reported to be effective for steroid-resistant TAK. However, there are no objective ways of diagnosing TAK recurrence because TCZ suppresses inflammatory biomarkers. ObjectivesTo investigate the efficacy of TCZ at 1-year follow-up and of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography for detection of recurrence of inflammation during TCZ treatment. Methods and ResultsWe treated 19 patients with refractory TAK with TCZ. TCZ was discontinued in 2 cases because of side effects. Abatement of arteritis symptoms along with reduction of glucocorticoid dosage was achieved in 12 patients, resulting in a remission induction rate of 70.6%. The dosage of glucocorticoid was reduced from 16.1 ± 10.2 mg to 3.8 ± 1.7 mg at 1 year (p<0.001) in these patients. In the remaining 5 patients, glucocorticoid tapering led to exacerbation of symptoms and glucocorticoid dose had to be increased. FDG-PET scan results closely matched clinical course in all 5 patients with recurrence even during TCZ treatment, while the scan was negative for the remaining 12 patients. ConclusionsTCZ injection provides robust steroid-sparing effect and improvement of inflammation without significant adverse effects. Recurrence of inflammation can be detected by FDG-PET even during TCZ treatment.