Rheumatoid Arthritis: Yin M

Breedveld F, Agarwal S, Yin M, Ren S, Li NF, Shaw TM, Davies BE. · Leiden University Medical Center, Rheumatology, PO Box 9600, Leiden, 2300 RC, the Netherlands. · J Clin Pharmacol. · Pubmed #17766699 No free full text.

Abstract: This study characterized the relationship between clinical response, serum rituximab concentrations, and peripheral B-cell levels in patients with rheumatoid arthritis treated with rituximab. Data were analyzed from a double-blind, phase IIa trial in which 161 patients with active rheumatoid arthritis despite continuing methotrexate were randomized to methotrexate alone (10-25 mg/wk), rituximab alone (single course: 1000 mg administered intravenously on days 1 and 15), rituximab plus cyclophosphamide (750 mg administered intravenously on days 3 and 17), or rituximab plus methotrexate. Serum samples for pharmacokinetic analysis were collected through 24 weeks, and peripheral circulating CD19+ B-cell levels were measured through 48 weeks. All treatments were generally well tolerated, with no clinically relevant excess of adverse events leading to withdrawal among patients who received rituximab compared with those who received methotrexate alone. The proportions of patients who achieved an American College of Rheumatology score of 50 at week 24 were 13% (methotrexate alone), 33% (rituximab alone), 41% (rituximab plus cyclophosphamide), and 43% (rituximab plus methotrexate). Peripheral B-cell depletion occurred by day 15 in all patients treated with rituximab. There was no relationship between B-cell depletion and clinical response. Recovery of peripheral B cells was variable and showed no relationship with return of disease activity in patients who responded to rituximab. The mean terminal half-life of rituximab was 19 to 22 days; pharmacokinetic parameters were similar whether rituximab was administered alone or with methotrexate or cyclophosphamide. Because the level of peripherally circulating B cells does not appear to correlate with a maintained clinical response in patients with rheumatoid arthritis, the timing of rituximab retreatment should be based on clinical symptoms rather than peripheral B-cell levels.

Strand V, Balbir-Gurman A, Pavelka K, Emery P, Li N, Yin M, Lehane PB, Agarwal S. · Division of Immunology, Stanford University, Palo Alto, CA, USA. · Rheumatology (Oxford). · Pubmed #17062648 links to  free full text

Abstract: OBJECTIVES: To evaluate the long-term impact on physical function of a single course of rituximab in rheumatoid factor, seropositive patients with active rheumatoid arthritis (RA) despite ongoing methotrexate treatment. METHODS: A randomized, controlled trial comparing rituximab alone [1,000 mg intravenously (iv) on days 1 and 15, n= 40], or in combination with cyclophosphamide (750 mg iv on days 3 and 7, n= 41) or oral methotrexate (> or =10 mg/week, n= 40) with placebo + methotrexate (> or =10 mg/week, n= 40), resulted in significant reductions in disease activity at weeks 24 and 48. Sustained improvements in physical function and standard effect sizes (SES) for changes in components of ACR and EULAR criteria were evaluated over 2 yrs. RESULTS: More patients receiving rituximab + methotrexate completed a 2-yr follow-up without further treatment than those receiving placebo + methotrexate (45% vs 15%, respectively), rituximab alone (10%) or rituximab + cyclophosphamide (22%). This reflected a higher percentage of patients receiving rituximab + methotrexate reporting improvements in Health Assessment Questionnaire Disability Index > or = minimum clinically important difference at 1 and 2 yrs (68% and 30%, respectively) compared with placebo + methotrexate (28% and 15%), rituximab monotherapy (43% and 10%) or rituximab + cyclophosphamide (39% and 12%). SES were high in all rituximab groups and revealed differing patterns of response over time. CONCLUSION: A single course of rituximab with continuing methotrexate in patients with active RA provided clinically meaningful improvements in physical function over 2 yrs, with lower discontinuation rates and larger SES for improvements in ACR and EULAR criteria components.