P183 Assessing the safety of treatment cessation in Takayasu arteritis
Authors: Dahanayake Chanaka , Maughan Robert , Youngstein Taryn , Mason Justin C 
Published: April 2020

Abstract

Background
Takayasu arteritis (TA) is a chronic granulomatous large vessel vasculitis. Patients typically receive immunosuppressive therapies, often continued indefinitely. Despite recent publication of recommendations for treatment initiation in TA, there is limited data on whether immunosuppressive treatments can ever be safely withdrawn. Our aim was to investigate the characteristics and outcomes of patients in long-term remission in whom immunosuppressive treatment had been stopped.

Methods
Clinical and radiographic data from a cohort of 160 TA patients followed-up over 20 years in a single tertiary specialist centre were analysed cross-sectionally, identifying those in whom immunosuppressive treatment was fully withdrawn. Baseline demographic data was collected and compared to those remaining on treatment. Outcomes assessed included status of follow-up imaging, change in inflammatory markers (CRP and ESR) and National Institute of Health (NIH) scores where data was available. A Mann Whitney U test was used for statistical analysis.

Results
Of the 160 patients analysed, 134 required treatment of whom 22 (16%) (all female, median age 47 years) had treatment fully withdrawn, after receiving immunosuppression for &gt;6 months. Median age at diagnosis was 30 years and median number of arteries involved was 3. In those remaining on treatment, 89% were female (median age 47 years). All those withdrawn from treatment had received prednisolone, 15 methotrexate, 8 azathioprine, 2 mycophenolate and 2 cyclophosphamides. Median duration of treatment was 106 months (IQR 104 months). Median time from treatment cessation to analysis was 26 months (IQR 67 months). All 22 patients remained alive at the time of analysis, 17 (77%) had follow-up imaging post-treatment withdrawal (5 currently awaited). Only one patient suffered a disease flare after immunosuppression was stopped. This occurred 4 months post-withdrawal, confirmed by imaging with a positive FDG-PET scan, concurrent increases in inflammatory markers and NIH score consistent with new active disease. In the 21 cases in whom treatment was successfully withdrawn, CRP and ESR results pre- and post-treatment cessation were not significantly different (p = 0.944 and p = 0.322 respectively). Likewise, NIH scores compared pre- and post-treatment withdrawal revealed a median change 0 (range -1 to + 3).

Conclusion
Little data exists on the cessation of immunosuppression in complex rheumatic disease. Of 160 TA patients, 21/22 patients off treatment had stable outcomes. The baseline characteristics of this sub-group did not differ significantly from the whole cohort, however none of them had ever received biological therapy, suggesting a less refractory course. Although these data demonstrate that immunosuppression can be safely withdrawn, the median duration of treatment was 106 months, raising the question of whether withdrawal should be attempted earlier. Biomarkers are required to help identify those in whom treatment can be withdrawn. We aim to develop protocols to facilitate safe treatment cessation in order to minimise treatment-related side-effects and with potential economic impact.

Disclosures
C. Dahanayake None. R. Maughan None. T. Youngstein None. J.C. Mason Other; Professor Mason has participated in medical board meetings with Roche/Chugai.