Review of the antiproliferative properties of mycophenolate mofetil in non-immune cells.

Mycophenolate mofetil (MMF), the prodrug ofmycophenolic acid (MPA), is a selective, non-competitive and reversible inhibitor of inosine monophosphate dehydrogenase (IMPDH) and of the type II isoform in particular. IMPDH is the rate-limiting enzyme in the de novo biosynthesis of guanosine nucleotides. MMF strongly inhibits both T- and B lymphocyte proliferation and has been used in the prevention of acute and chronic allograft rejection since the mid 1990s. Recent evidence, however, suggests that MMF is also capable of inhibiting the proliferation of non-immune cells. In various cell lines, i.e. smooth muscle cells, renal tubular cells and mesangial cells, MPA reduced or even abrogated proliferation in response to proliferative stimuli. Furthermore, data from our own laboratory demonstrate a dose-dependent inhibition of dermal fibroblast proliferation by MPA. In animal studies, MMF ameliorated renal lesions in immune-mediated disease, i.e. in the anti-thy 1.1 model and experimental lupus nephritis, but was also effective in non-immune-mediated renal damage in the rat remnant-kidney model. These observations prompted several investigators to study the effects of MMF in proliferating (renal) disease of non-immune origin in humans. MMF significantly reduced proteinuria in minimal-change disease and focal segmental glomerulosclerosis. In addition, MMF showed beneficial effects in the treatment of chronic allograft nephropathy and calcineurin inhibitor toxicity through reduction of immune- and non-immune-mediated renal damage. MMF is well tolerated and has proven to be a relatively safe drug causing only minor bone marrow suppression. Taken together, there is a growing body of evidence pointing to therapeutic applications of MMF other than immunosuppression, in particular the prevention of fibrosis.