Anti-adalimumab antibodies in juvenile idiopathic arthritis: frequent association with loss of response

OBJECTIVES: We aimed to determine how loss of response (LOR) to adalimumab (ADA) in juvenile idiopathic arthritis (JIA) may be related to anti-ADA antibodies (AAA). METHOD: AAA and ADA levels were measured in 23 consecutive patients with JIA responding significantly to treatment with ADA. RESULTS: Six out of 23 (26%) patients developed AAA and had low ADA levels. Five out of six AAA-positive patients experienced LOR. In these patients use of concomitant methotrexate (MTX) was significantly lower. CONCLUSIONS: The occurrence of AAA is a frequent event associated with LOR. Monitoring of AAA and serum ADA levels should be considered in JIA patients under ADA therapy.