The overall response rate of acute GVHD at day 28 and day 56 for all patients was impressive at 65.6 and 78% respectively as shown below. Single mycophenolic acid (MPA) pharmacokinetic measurements during weeks 1 and 2 after treatment did not correlate with CR at either day 28 or 56 (P > 0.07). However, as shown in Table II , if the mean of weeks 1 and 2 are taken together and the MPA trough was above the thresholds noted, more patients achieved CR 1 PR compared to cases where the MPA trough was low.