Safety, tolerability, and feasibility of antifungal prophylaxis with micafungin at 2 mg/kg daily in pediatric patients undergoing allogeneic hematopoietic stem cell transplantation.

INTRODUCTION: Micafungin (MCFG) is used for the prophylaxis of invasive fungal disease (IFD) after allogeneic hematopoietic stem cell transplantation (HSCT). However, the safety, efficacy, or optimal dosage/blood levels as prophylaxis is uncertain in pediatric HSCT-patients. METHODS: We prophylactically administered MCFG at 2 mg/kg once daily to 38 children and adolescents undergoing allogeneic HSCT. RESULTS: During MCFG prophylaxis, infusion reactions or adverse events (grades 2-5) related to MCFG use were not found in all the patients. Thus, MCFG prophylaxis was not discontinued and other antifungal agents were not added except for 2 patients in whom probable or possible IFDs developed (completion rate, 94.7 %). To elucidate the influence of HSCT-related complications/drugs on blood concentration of MCFG, we determined the plasma trough and peak levels in 13 and 10 among 38 patients, respectively. The mean trough and peak levels were 3.04 ± 1.21 µg/mL (569 samples) and 9.63 ± 3.62 µg/mL (44 samples), respectively. The peak levels were moderately correlated to the trough levels (R (2) = 0.466). In a patient, the trough level of MCFG transiently increased up to 10.21 µg/mL during hepatic dysfunction due to acute graft-versus-host disease. The MCFG trough levels strongly correlated with T-Bil value (R (2) = 0.894). There was no relationship between the trough levels of MCFG and the circulating concentrations of tacrolimus (R (2) = 0.040). Additionally, MCFG levels were not influenced by treatment with cyclophosphamide or corticosteroids. CONCLUSIONS: Prophylaxis with MCFG at 2 mg/kg once daily may be safe, tolerable, and feasible in pediatric HSCT-patients.