Objective: We assessed the effect of a daily dosing schedule of the chimeric anti-CD4 monoclonal antibody (MAb), cM-T412, in rheumatoid arthritis (RA) patients, and compared lymphocyte changes in the peripheral blood (PB) and synovial fluid (SF) of these patients.
Methods: Twelve patients received 50 mg/day of cM-T412 for 5 days, followed by a maintenance treatment of 50 mg/week for 5 weeks (6 patients), or a retreatment course of 50 mg/day for 5 days after 5 weeks (6 patients). Paired PB and SF samples were obtained during treatment for analysis.
Results: Changes in lymphocyte count and coating with the MAb in PB did not reflect changes in the SF. After 5 daily treatments, the percentage of cM-T412-coated CD4+ lymphocytes in SF correlated with the degree of clinical improvement seen in patients at 2 weeks after the initiation of therapy (r = 0.75, P < 0.05).
Conclusion: These results demonstrate the importance of antibody dosage and treatment regimen in determining clinical benefit. Our findings suggest that the percentage of cM-T412-coated CD4+ lymphocytes in SF may be a predictor of clinical outcome.