Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


Patients Not Responding to Etanercept Obtain Lower Trough Etanercept Concentrations Compared to Responding Patients.

Jamnitski1,  Anna, Nurmohamed1,  Michael T., Hart2,  Margreet M., Dijkmans3,  Ben A., Aarden2,  Lucien, Wolbink1,  Gerrit Jan

Jan van Breemen Institute
Sanquin Research
VU Medical Center

Purpose:

A substantial proportion of the patients with rheumatoid arthritis (RA) failed to respond on treatment with etanercept. Previous research has shown that etanercept appeared to be less immunogenic compared to adalimumab and infliximab. The goal of this study is to investigate the relationship between etanercept levels and clinical response in a large cohort of RA patients.

Methods:

Between 2004 and 2008, 292 consecutive patients with active RA (DAS28 > 3.2) and a new etanercept prescription were included in an observational cohort at the Jan van Breemen Institute, Amsterdam. Clinical response variables and etanercept levels were collected at baseline and after 1, 4 and 6 months of etanercept treatment. Trough serum etanercept levels were measured by ELISA (Sanquin research, The Netherlands). Last observation carried forward (LOCF) data was used for patients who discontinued the treatment with etanercept before 28 weeks. Differences between EULAR responders and non responders were evaluated by using an independent t-test, confounding analyses were performed using multiple regression analysis.

Results:

After 6 months of etanercept treatment 103 patients were good, 115 were moderate and 74 were non responders according to EULAR response criteria. Etanercept levels were undetectable at baseline (<0.001 mg/l). Patients with good EULAR response had significantly higher trough etanercept concentrations than EULAR non responders, p= 0.009 at 1 month and p<0.001 at both 4 and 6 months. To know, 3.40 (2.22 – 4.62) at 1 month, 3.98 (2.72 – 5.35) at 4 months and 3.78 (2.53 – 5.17) at 6 months in EULAR responders compared to 2.64 (1.20 – 3.89) at 1 month, 2.54 (1.12 – 3.94) at 4 months, and 2.80 (1.27 – 3.93) at 6 months in EULAR non responders. No antibodies were detected against etanercept.

Conclusion:

This study demonstrates for the first time that patients with good EULAR response obtain significantly higher levels of etanercept than patients not responding to etanercept treatment. Furthermore this study confirms that etanercept is less immunogenic than another TNF-inhibitors.

To cite this abstract, please use the following information:
Jamnitski, Anna, Nurmohamed, Michael T., Hart, Margreet M., Dijkmans, Ben A., Aarden, Lucien, Wolbink, Gerrit Jan; Patients Not Responding to Etanercept Obtain Lower Trough Etanercept Concentrations Compared to Responding Patients. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :1825
DOI: 10.1002/art.29590

Abstract Supplement

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