A Randomized, Multicenter Study to Assess the Efficacy on Diseases Activity of Enteric-coated Mycophenolate Sodium Versus Continuation of Azathioprine in Patients With Systemic Lupus Erythematosus on Azathioprine Maintenance Therapy.

Systemic lupus erythematosus (SLE) is a complex and potentially life-threatening disease that affects about 40 per 10,000 people in the general population (Mills 1994, Brown & Schrieber 1996). SLE is a chronic inflammatory disease characterized by auto-antibody overproduction and other distinct immunological abnormalities (Boumpas, et al 1995, Mohan & Datta 1995). It may affect the skin, joints, lungs, heart, serous membranes, nervous system or other organs. Improvements in treatment over the last decade have increased 10-year survival rates in Western countries to 90% or more, and 20-year survival rates of nearly 70% have also been reported (Abu-Shakra, et al 1995).

Newer treatment strategies include the use of novel immunosuppressive agents, such as mycophenolate mofetil (MMF). MMF has been widely used in solid-organ transplantation (Sollinger 1995, The Tricontinental Mycophenolate Mofetil Renal Transplantation Study Group 1996). MMF also has been used increasingly in autoimmune diseases (e.g., dermatomyositis, primary glomerular disease or psoriasis (Epinette, et al 1987, Gelber, et al 2000, Choi, et al 2002)).

MMF is the morpholinoethylester prodrug of mycophenolic acid (MPA). After oral administration MMF is well absorbed and rapidly hydrolyzed to MPA. MPA is a noncompetitive inhibitor of inosine monophosphate (IMP) dehydrogenase (DH). Inhibition of IMPDH leads to the depletion of deoxyguanosine triphosphate and a consequent decrease in the level of substrate required for DNA polymerase activity. This results in inhibition of DNA production and cell proliferation. T and B cells are more dependent on this de novo pathway of purine synthesis because alternative salvage pathways are unavailable. Thus, MPA is a selective inhibitor of lymphocyte proliferation, especially in activated lymphocytes (Allison & Eugui 2000).

A limited number of clinical studies have been performed to study the efficacy of MMF in the treatment of SLE. Most of these studies involved the treatment of nephritis. Chan, et al (2000) showed that the combination of MMF and prednisolone is as effective as a regimen of cyclophosphamide and prednisolone followed by azathioprine and prednisolone. Azathioprine and MMF as maintenance therapy were compared to cyclophosphamide therapy (Contreras, et al 2004) and appeared to be more efficacious and safer than long-term therapy with i.v. cyclophosphamide. In this study, it was also noted that patients treated with MMF had received lower doses of corticosteroids during maintenance therapy as compared to patients treated with azathioprine.

Recent reports suggest that MMF may also be effective in systemic lupus without severe renal involvement.(Pisoni, et al 2005) Yet, the superiority over azathioprine in this patient group has not been established. Own observations show that approximately 50% of patients with SLE treated with azathioprine have at least some evidence of lupus activity. The aim of this study will be to show a decreased lupus activity in patients treated with myfortic ® compared to therapy with azathioprine. Data so gathered may be useful in planning future developments in this indication