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SAT0385 Immunogenicity, Tnf-Inhibitors Levels and Disease Outcomes in Ankylosing Spondylitis: Results from An Observational Cohort Study
  1. C. Ancuta1,2,
  2. C. Pomirleanu1,2,
  3. C. Belibou1,
  4. R. Maxim1,
  5. L. Petrariu1,
  6. G. Strugariu1,
  7. I. Esanu2,
  8. R. Chirieac3,
  9. E. Ancuta4
  1. 1Rheumatology 2, Clinical Rehabilitation Hospital
  2. 2University of Medicine and Pharmacy “Gr.T.Popa”
  3. 3Sanocare - Medical and Research Center
  4. 4Research Department, “Elena Doamna” Clinical Hospital, Iasi, Romania


Background Up to one third of spondylarthritis (SpA) fail to respond to anti-TNF agents or experience drug toxicity leading to treatment withdrawal. Part of the treatment failure can be explained by the development of anti-drug antibodies (ADA).

Objectives To evaluate the relation between immunogenicity, drug levels and clinical efficacy of TNF inhibitors (TNF-i) in ankylosing spondylitis (AS).

Methods We performed a prospective observational study in a cohort of 47 consecutive AS patients receiving adalimumab (ADL) (13; 27.7%), infliximab (IFX) (13; 27.7%) or etanercept (ETN) (21; 44.7%). Disease

Disease activity (BASDAI, ASDAS), outcomes and adverse events were evaluated at baseline and study visit, while serum TNF-i and ADA levels collected as a single-point data in both bio-naïve (37, 78.7%) and bio-experimented patients. Serum drug levels were considered positive for IFX if >0.035 μg/mL, for ADL >0.024 μg/mL and for ETN >0.035 μg/mL, while the cut-off value for the ADA positivity to IFX was established at 5AU/ml, for ADL at 10AU/mL and ETN at 142 AU/mL (ELISA, Progenika).

Statistical analysis was performed using SSPS version 19.0, p<0.05

Results At baseline mean BASDAI was 7.69 and mean ASDAS-CRP 3.50, with no difference in disease activity between patients who did or did not later develop ADA (p<0.05). 37 (78.7%) AS were BASDAI responders at study visit (BASDAI 1.16, ASDAS-CRP 1.73).

ADA were detected in 8/47 (17%) and were more frequent in patients treated with ADL (5 cases; 38.5%) vs IFX (3 cases; 23.1%); no with ETN. Both ADL and IFX levels were significantly higher for ADA negative than for ADA positive patients (ADL: 3.92μg/mL vs 0.02μg/mL, p<0.01; IFX: 1.82μg/mL vs 0.03 μg/mL, p<0.01).

A significant association between clinical activity (ASDAS) and immunogenicity (ADA status) was reported: patients who had developed ADA had higher disease activity (3.10 vs 1.73, p<0.01), and more patients were classified as being in a high or very high disease activity status.

Furthermore, a relation between clinical improvement (change in ASDAS) and immunogenicity was reported: ADA-positive AS achieved worse clinical response than ADA-negative cases, with a significant association between ADL respectively IFX levels and ASDAS (p<0.05).

Conclusions ADL and IFX levels are commonly influenced by ADA-positivity, and related to clinical response in AS, suggesting that therapeutic drug monitoring should be investigated as a possible tool to optimise treatment such patients.

  1. Arstikyte I et al. Influence of Immunogenicity on the Efficacy of Long-Term Treatment with TNFα Blockers in Rheumatoid Arthritis and Spondyloarthritis Patients. BioMed Research International 2015

  2. Hoxha A, et al. The clinical relevance of early anti-adalimumab antibodies detection in rheumatoid arthritis, ankylosing spondylitis and psoriatic arthritis: A prospective multicentre study. Joint Bone Spine 2015

Disclosure of Interest None declared

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