An enteric-coated formulation of mycophenolate sodium (EC-MPS, Myfortic) has been developed especially to reduce MPA-related gastrointestinal adverse events. This clinical trial is a prospective controlled study to evaluate whether a Myfortic based regimen will be able to reduce the probability of a relapse compared to steroid therapy alone and to test whether a Myfortic based therapy provides a superior behaviour compared to a steroid regimen.