A double‐blind, placebo‐controlled study of anti‐CD5 immunoconjugate in patients with rheumatoid arthritis

Objective. To evaluate the efficacy of an anti‐CD5 ricin‐linked immunoconjugate (CD5‐IC) in patients with rheumatoid arthritis (RA). Methods. A total of 104 evaluable patients were enrolled in a multicenter, double‐blind, multiple‐dose, placebo‐controlled study of CD5‐IC. Results. Treatment with CD5‐IC in doses up to 8 mg/m2/day for 4 days in 1 month failed to produce marked or prolonged T cell depletion and was no more effective than placebo in ameliorating disease manifestations. An unexpectedly high placebo response was observed in 48% of the patients. Adverse events were correlated with the dose of CD5‐IC, but the treatment was generally well‐tolerated. Conclusion. At the doses used in this study, CD5‐IC was ineffective for treating RA.