This is a Phase III, 6 month randomized, double-blind, placebo controlled multi-center study with a 6 month open-label extension. Patients will be randomized to the tacrolimus + methotrexate arm or the placebo + methotrexate arm in a ratio of 2:1. Patients who complete the 6-month double-blind phase will be eligible to enroll in the open-label phase of the study.