Muromonab CD3. A review of its pharmacology and therapeutic potential.

Muromonab CD3 (Orthoclone OKT3, Orthoclone, OKT3) is the first monoclonal antibody to become available for therapy in humans. In effect it blocks all cytotoxic T cell function. Clinical trials show that muromonab CD3 is effective in reversing acute renal, hepatic, cardiac and combined kidney-pancreas transplant rejection episodes. It has also been shown to be effective in the treatment of rejections resistant to conventional treatment. As such it offers a significant alternative when no other therapeutic option remains open. Other clinical trials have shown that muromonab CD3 is more effective than high-dose corticosteroids in reversing first episodes of acute renal and hepatic rejection. Additionally, it appears effective as a prophylactic treatment against acute renal and cardiac rejection in the immediate post-transplantation period. Preliminary studies also indicate that it may be effective in preventing or reversing graft-versus-host disease in bone marrow transplant patients. The development of neutralising antibodies may limit the effectiveness of a second course of muromonab CD3 therapy in some patients. In conclusion, muromonab CD3 offers a significant new approach to immunosuppressive therapy and has provided a valuable therapeutic alternative for the treatment of acute solid organ transplant rejection.