Background Rituximab is an anti-CD20 antibody that represents a therapeutic alternative for the patients with rheumatoid arthritis. It has been proven that Rituximab at a dose of 2 gm is very effective in patients with DMARD and antiTNF failures. But the cost of this therapy is high and increases the economic burden. Limited data has shown that B cell is possible even with lower dosage to what is recommended.

Objectives 1) To assess B cell depletion with very low dose single dose of 100mg Rituximab

2) To assess improvement in disease activity (EULAR response)

Methods In this open label, prospective, observational study at tertiary care center sero positive RA patients who responded inadequately to combination of DMARDs were given single dose of 100 mg of Rituximab. B cell numbers in the peripheral blood was assessed by Flow cytometry and B cell depletion was defined as B cell numbers <0.01%. Efficacy was evaluated using B cell depletion after 2 weeks and disease activity score in 28 joints (DAS28) on monthly bases. Those patients who did not achieve B cell depletion and/or EULAR moderate response were given second dose of rituximab 500mg.

Results 15 patients (13 females and 2 males; mean age 47.7±13.95 years) were included in the study. Mean duration of the disease was 7.3±6.01 years. RF was positive in 14 out of 15 and Anti CCP antibody was positive in all patients. At baseline mean DAS score was 6.14±0.84 and mean CD 19% was 10.69±4.35%. After 2 weeks of Rituximab, B cell depletion was achieved in 12 patients (80%) and mean DAS28 was 2.72±0.57 at the end of 24 weeks. Two patients were given second dose of 500mg Rituximab after 8 weeks of first dose. All patients achieved EULAR good response at the end of 24 weeks.

Conclusions Early results from this study are very promising and show that low dose Rituximab is effective in treating RA patients inadequately responding to DMARDS.

References

1. Edwards JC, Szczepanski L, Szechinski J et al. Efficacy of B-cell-targeted therapy with rituximab in patients with rheumatoid arthritis.N Engl J Med. 2004 Jun 17;350(25):2572-81;

2. Mease PJ, Revicki DA, Szechinski J et al.;Improved health-related quality of life for patients with active rheumatoid arthritis receiving rituximab: Results of the Dose-Ranging Assessment: International Clinical Evaluation of Rituximab in Rheumatoid Arthritis (DANCER) Trial. J Rheumatol. 2008 Jan;35(1):20-30. Epub 2007 Nov 15.

3. Anolik JH, Barnard J, Cappione A et al. Rituximab improves peripheral B cell abnormalities in human systemic lupus erythematosus;Arthritis Rheum. 2004 Nov;50(11):3580-90;

4. Bruzzese V. et al. Therapeutic effectiveness of minimal doses of rituximab in a patient with rheumatoid arthritis; Int J Immunopathol Pharmacol. 2011 Jan-Mar;24(1):265-7

Acknowledgements We acknowledge flowcytometry lab incharge,chairman-ethics committee and medical director of institute.

Disclosure of Interest None declared