EFFECTS OF ADMINISTRATION OF AN ANTI-CD5 PLUS IMMUNOCONJUGATE IN RHEUMATOID-ARTHRITIS - RESULTS OF 2 PHASE-II STUDIES

Objective. To evaluate the safety and activity of an immunoconjugate of ricin A chain and anti-CD5 monoclonal antibody (anti-CD5 IC), with and without concomitant methotrexate and/or azathioprine, in the treatment of rheumatoid arthritis (RA). Methods. Seventy-nine patients with active RA were enrolled in 2 prospective open-label protocols. Results. Using composite criteria, response rates were 50-68% at 1 month and 22-25% at 6 months. Transient depletion of CD3/CD5 T cells was observed on days 2 and 5 of treatment, with reconstitution on day 15 or day 29. Treatment-associated adverse effects were common but resolved rapidly without sequelae. Conclusion. These findings suggest activity of anti-CD5 IC in active RA and warrant confirmation in a multicenter randomized study (currently underway).