Targeting mycophenolate mofetil for graft-versus-host disease prophylaxis after allogeneic blood stem cell transplantation

As low trough levels of mycophenolic acid (MPA) have been measured in recipients of allo-SCTs, we performed a pilot study targeting mycophenolate mofetil (MMF) doses according to the MPA area under the concentration (AUC) levels. Twenty-nine patients were transplanted from matched sibling (n=7) and unrelated donors (n=22). Tacrolimus was given orally from day −1 to achieve trough blood levels of 5–10 ng/ml. MMF was started on day 0 at 1500 mg intravenously b.i.d. AUC measurements of MPA by HPLC were scheduled on days 3, 7 and 11 after transplantation. The MMF dose was modified to achieve an MPA AUC of 35–60 μg/ml/h. With the respective adjustments 66 and 75% surpassed the lower AUC target on days 7 and 11, respectively. The cumulative incidence of grade III–IV acute GVHD was 28% (8/29). Eight out of 24 evaluable patients (33%) suffer from limited (n=3) or extensive (n=5) chronic GVHD. Overall, the results of this study suggest that targeting of MPA exposure is feasible early after transplantation. A simplified MMF targeting strategy based on MPA Cmax or C2h levels seems to be warranted in future trials involving more patients at later time points in the outpatient setting.