Cyclosporine, RK-506, rapamycin, and other immunomodulators

Immunomodulatory agents represent a unique group of therapies that are not biologics and have relatively specific, noncytotoxic effects on the immune system. Cyclosporine has been the most widely tested of the immunomodulatory agents and shown efficacy in a variety of autoimmune diseases as well as monotherapy in established rheumatoid arthritis. FK-506 and rapamycin, agents similar to cyclosporine, are being tested in human transplantation, with only arthritis studies having been done in animals. Tilomisole, imuthiol, and mycophenolate mofetil have been studied in limited rheumatoid arthritis trials with positive effects. Although more specific and with manageable short-term side effects, this group of therapies requires more studies to establish their efficacy and long-term safety.