부산대학교 도서관

BACKGROUND: Immunogenicity influences adalimumab levels and therefore clinical response in patients with rheumatic diseases. OBJECTIVES: To study the relationship between clinical response, adalimumab levels and antidrug antibodies (ADAb) in ankylosing spondylitis (AS). METHODS: Observational cohort study of 115 consecutive AS patients treated with adalimumab in the Netherlands (n=85) and Taiwan (n=30), monitored during 24□weeks. Adalimumab levels and ADAb titres were determined using an ELISA and an antigen binding test (ABT), respectively, designed by Sanquin Research, Amsterdam. Response to adalimumab treatment was defined as a Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) response, and disease activity was measured using the Ankylosing Spondylitis Disease Activity Score using C-reactive protein (CRP) (ASDAS). RESULTS: At baseline, median BASDAI (IQR) was 6.4 (4.5-7.6) and mean ASDAS (SD) was 3.5 (1.0). After 24□weeks, 49 (42.6%) patients were BASDAI50 responders and mean ASDAS (SD) for responders was 1.5 (1.0) vs 2.6 (1.0) for non-responders (p<0.001). Thirty-one (27.0%) patients had detectable ADAb. After 24□weeks, adalimumab levels (mg/L) (IQR) were significantly higher in ADAb-negative patients than in ADAb-positive patients (12.7 (8.2-18.0) vs 1.2 (0.0-2.0), (p<0.001)). A significant association was demonstrated between adalimumab levels and ASDAS (p=0.02; RC −1.1; 95% CI −2.0 to −0.2). Eleven (9.6%) patients had no detectable adalimumab levels and high detectable ADAb titres (>100□AU/mL). In these patients, CRP and erythrocyte sedimentation rate remained elevated during treatment. CONCLUSIONS: Adalimumab levels are related to clinical response in AS patients measured with ASDAS and are influenced by ADAb detectable with an ABT.