Pharmacokinetics-based optimal dose prediction of donor source-dependent response to mycophenolate mofetil in unrelated hematopoietic cell transplantation

Mycophenolate mofetil (MMF) has been widely used for prophylaxis against graft-versus-host disease (GVHD) following allogeneic hematopoietic stem cell transplantation (allo-SCT). However, no clear advantage over methotrexate has been reported, other than reduced incidence of mucositis. We speculated that the wide inter-individual variation of plasma mycophenolic acid (MPA) levels veiled the benefits of MMF. Data from 36 unrelated allogeneic bone marrow (allo-BMT) and cord blood transplantation (CBT) were analyzed retrospectively based on MPA area under the curve (AUC _0-24h). In allo-BMT, high AUC _0-24h (>30 μg h/ml) resulted in no incidence of grade II-IV acute/extensive chronic GVHD and tended to show higher overall and disease-free survival, lower relapse rates, and non-relapse mortality. In CBT, AUC _0-24h less than 30 μg h/ml was sufficient for low incidence of acute/chronic GVHD and high survival. Strong correlation between AUC _0-24h and C _2h, plasma MPA concentration at 2 h after administration was observed. Single point assessment of C _2h was shown to provide a useful surrogate of AUC _0-24h to predict GVHD incidence. The results of this study suggest that individualized MMF dosing in a donor source-dependent fashion may be important for maximizing the benefit of MMF in allo-SCT.