AB1308 FAILURE TO BIOLOGICAL THERAPY: WHEN TO EXPECT IT?
Authors: rim dhahri, Salma Athimni, Maroua Slouma, Leila Metoui, Imen Gharsallah, Bassem Louzir, Maroua Meddeb, Mahdi Dridi
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background:</h3> Using Biologic agents, has considerably improved the treatment of inflammatory diseases.But it is associated to thecapacity of inducing an immune response in patients that could result in unwanted adverse events or treatment failure. <h3>Objectives:</h3> The aim of this work was to compare the clinical and biological response to biotherapy with the presence of ADA and the residual dose rate. <h3>Methods:</h3> We analysed the medical records of 69 patients treated with biotherapy between September 2017 and October 2018.3 pathologies were considered: rheumatoid Arthritis (RA) diagnosed by ACR/EULAR 2009 criteria, Spondylarthritis (SPA) according to Assessment of Spondylarthritis international Society (ASAS) And crohn'sdisease (CD) classified upon the 2006' Montreal classification. We did search the presence of anti-bodyanti-drugs (ADA) and the residual dose for the following therapies: Etanercept (ETN),Infliximab (IFX), Adalimumab (Ada)or Rituximab (RTX). <h3>Results:</h3> The mean age was 43.33 ± 11.4 year. The sexratio M/F was 1.57. Regarding the RA: they were 13 patients. 10 had positive (ACPA) and seven positive (RF). All the patients had an initial treatment by conventional synthetic disease-modifying antirheumatic drugs(csDMARDs) before moving to bDMARDs. 14 were in concomitant disease-modifying therapy. The DAS28-ESR average was at 4.12 [2.67 - 5.79]. we found positive ADA in only one patient analysis. There were 8 responding versus five non-responding patients,according to the clinical and biological evaluation of disease activity. 28 patients were In the SPA group: 13 with an axial spondyloarthritis. 14% had the HLAB 27. It was an active disease in 15 cases. ASDAS-CRP average was 4,87 ± 0,17 [4.7; 5]. The received biotherapy was IFX 50%, ETN 28.6% and Ada 21.4%. 10 patients had a positive ADA and 8 of them had a rate superior to 100 UI. 19 patients were considered as non-Responding. In the CD group, 28 patients were enrolled. All oft hem had a previous immunosupressor treatment. Same patients in association with biotherapy. It was positve ADA in 7 cases. And 7 patients were non-responding to the treatment. The residual dose of drugs was calculated for each drug and it is explained in the following table : Positve ADA was associated with therapy failure in all type of biotherapy (p=0.001). A low residual dose was associate to therapy failure only in the case of IFX (p=0.005). In multivariate analyses, the predictive factors associated with therapeutic failure were : positive ADA(p=0.008)and advanced age at diagnosis, bellow 30 years old age (p=0.020). Hosmer index=0.452. <h3>Conclusion:</h3> Immune response induced in patients treated with biotherapy can be quantified now thanks to ADA dosage and the residual dose assessment. <h3>References</h3> [1] Kristensen LE, Kapetanovic MC, Gülfe A, Söderlin M, Saxne T, Geborek P. Predictors of response to anti-TNF therapy according to ACR and EULAR criteria in patients with established RA: results from the South Swedish Arthritis Treatment Group Register. Rheumatology (Oxford). 2008;47:495-9. [2] Lanfant-Weybel K, Lequerré T, Vittecoq O. Anti-TNF alpha dans le traitement de la polyarthrite rhumatoïde et de la spondylarthrite ankylosante. Presse Med. 2009;38:774-87. <h3>Disclosure of Interests:</h3> None declared