Objective To study the impact of B-cells depleting therapy (RTM) on joint destruction in correlation with B-cells counts.

Materials and methods The study included 61 RA pts (average disease duration 10,1±7,7 y., mean DAS28 6,3±0,94, RF-positive - 87%, ACCP–positive 93%) undergoing RTM therapy. Clinical effect was scored by EULAR criteria, radiographic progression was assessed using Sharp/van der Heijde (SvH) modified scoring method. B-cell level was measured with flow cytometry.

Results By Week 48 after 2 RTM course good response was documented in 29,7% pts, good and satisfactory - in 85,3%; remission was achieved in 14,6% pts. There was no radiographic progression in remission pts., in 83% of pts with low disease activity and in 33% - with moderate disease activity. Of note, further progression in joint space narrowing was more pronounced than bony tissue destruction - in 32% and 25%m respectively. Clinical and anti-destructive effects were often dis-matching: bone destruction was abrogated without any clinical improvement in 54% of pts. There was no significant difference in clinical effects of RTM dosing regimens (1000 mg x2 or 500 mg x2). More potent anti-destructive effect was documented in pts getting higher RTM dose values. No significant influence of B-cells depletion on radiographic progression of the disease was noticed. Although, in RA pts achieving remission B-cell depletion was more notable as compared to pts with active disease.

Conclusion Therapeutic effect of two dosing regimens was similar, but the protective effect against bone destruction was more pronounced with higher RTM doses. Radiographic progression did not show any correlation with the degree of B-cells depletion. Most pronounced B-cells depletion was documented in pts achieving remission.