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.
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.
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).
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.