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Assessment of rituximab’s immunomodulatory synovial effects (ARISE trial). 1: clinical and synovial biomarker results
  1. A Kavanaugh1,
  2. S Rosengren1,
  3. S J Lee1,
  4. D Hammaker1,
  5. G S Firestein1,
  6. K Kalunian1,
  7. N Wei2,
  8. D L Boyle1
  1. 1
    University of California, San Diego, Division of Rheumatology, Allergy, and Immunology, La Jolla, California, USA
  2. 2
    Arthritis and Osteoporosis Center of Maryland, Fredericksburg, Maryland, USA
  1. A Kavanaugh, University of California, San Diego, Division of Rheumatology, Allergy, and Immunology, 9500 Gilman Drive, Mail Code 0943, La Jolla, CA 92093-0943, USA; akavanaugh{at}ucsd.edu

Abstract

Objective: Treatment with the anti-CD20 monoclonal antibody (mAb) rituximab is effective in rheumatoid arthritis (RA). Marked depletion of circulating B cells, seen in almost all patients, does not correlate with efficacy. The potential synovial immunomodulatory effects of rituximab have not been fully defined.

Methods: The ARISE trial is an open label, serial synovial biopsy (pre-treatment and 8 weeks) study of rituximab, given 1 g intravenously on days 0 and 14 without peri-infusional steroids, in active RA patients on concomitant methotrexate (MTX). Synovial tissue was analysed by immunohistochemistry with digital image analysis and gene expression by real-time PCR.

Results: The mean (SD) baseline DAS28 score was 6.5 (0.4), and mean MTX dose 17.3 mg/week. Of 13 patients, 11 had failed prior tumour necrosis factor (TNF) inhibitor therapy. With treatment, all patients experienced near complete depletion of circulating B cell numbers. During the 6 months after treatment, 7/13 patients achieved an American College of Rheumatology (ACR) 20% improvement (ACR20) response, 3/13 an ACR50 response and 2/13 an ACR70 response. There was a significant decrease in synovial B cells after treatment, but only a small trend towards greater reduction among clinical responders. Among the three patients with ACR50 responses there was a significant decrease in synovial immunoglobulin synthesis.

Conclusions: These data suggest that unlike those in circulation, synovial B cells are decreased but are not eliminated by rituximab therapy. Patients with higher levels of response may have more consistent depletion of synovial B cells, and may also have an alteration in synovial B cell function, as indicated by decreases in synovial immunoglobulin synthesis. Thus, effects on synovial B cells may be necessary but not sufficient for inducing clinical efficacy. Other effects, such as on primary lymph organ B cell antigen presentation or cytokine production, may be operative.

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Footnotes

  • Competing interests: None declared.

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