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AB0337 Blood b cell counts as predictor of early clinical response after rituximab in patients with rheumatoid arthritis
  1. Y. J. Kim1,
  2. B. S. Koo1,
  3. M.-W. So1,
  4. W. J. Seo2,
  5. Y.-G. Kim1,
  6. C.-K. Lee1,
  7. B. Yoo1
  1. 1Division of Rheumatology, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine
  2. 2Division of Rheumatology, Department of Internal Medicine, Seoul Veterans Hospital, Seoul, Korea, Republic Of

Abstract

Background B cell depletion with rituximab is effective for reducing the symptoms and inhibiting the progression of joint damage in patients with rheumatoid arthritis (RA). However, the use of peripheral B cell counts as a predictive factor of clinical response is limited.

Objectives We aimed to investigate the potential value of measurement of peripheral blood B cell counts after rituximab therapy in patients with active RA refractory to anti-tumor necrosis factor inhibitors.

Methods A total of twenty-seven RA patients whom received more than 1 cycle (two 1-gram infusion) of rituximab were included in this study. Absolute B cell counts on day 1 and 15 before each rituximab infusion was measured by conventional flow cytometry. On day 15, peripheral B cell levels below 2.5 X 106 cells/liter was defined as B cell depletion and the clinical response was analyzed between the 2 groups; depletion vs. non-depletion. Clinical response at 18 weeks after 1st infusion of rituximab was measured by Disease Activity Score in 28 joints (DAS28) using the erythrocyte sedimentation rate. The analysis of B cell depletion with regard to DAS28 and continuous variables were performed using Mann-Whitney test.

Results The mean age at rituximab treatment was 55 ± 13.8 (25-83) years and the baseline DAS28 was 6.6 ± 0.9 (4.4-8.1). The positive rate of RF and ACPA was 90% (27/30) and 72.2% (13/18), respectively. B cells on day 15 was depleted in 17 (56.7%) patients with median value of B cell counts as 1.2 X 106 cells/liter [range 0.0∼2.5 X 106/liter]). Patients in whom B cell depletion was not achieved showed persistently high DAS28 (4.7 ± 0.6 versus 3.3 ± 1.0 [p = 0.007]) by 18 weeks and significant short duration of B cell depletion time (4.0 ± 2.3 versus 8.2 ± 4.3, months [p = 0.008]) than those in depletions.

Conclusions Data derived from B cell depletion with rituximab in active RA patients suggest that measurement of peripheral B cell counts on 15th day might provide clinical information on early response and non-depletion of B cells can be used as a predictive factor of poor response.

  1. Efficacy of B-cell-targeted therapy with rituximab in patients with rheumatoid arthritis. NEJM (2004) 350(25). 2572-81

Disclosure of Interest None Declared

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