Twice daily i.v. bolus tacrolimus infusion for GVHD prophylaxis in children undergoing stem cell transplantation

Tacrolimus is routinely administered for GVHD prophylaxis as a 24-h continuous infusion that requires a dedicated i.v. line and thus becomes logistically difficult to administer, especially in young pediatric patients. We investigated the safety and efficacy of twice daily bolus infusions of i.v. tacrolimus in 33 children undergoing hematopoietic stem cell transplantation (HSCT) at our institution. Tacrolimus was started at an initial dose of 0.015 mg/kg i.v. bolus administered as a 2-h infusion and then given at every 12 h to maintain a trough drug level between 515 ng/mL. Patients also received short-course MTX (66%) or mycophenolate mofetil (34%) in combination with tacrolimus. No acute infusional toxicities were observed with bolus infusions of i.v. tacrolimus. Nephrotoxicity occurred in 14/33 (42%) patients and 48% developed hypertension (HT). Almost all (94%) patients required magnesium supplements to maintain magnesium (Mg) levels 1.5 mg/dL. In all, 3 (9%) patients developed severe sinusoidal obstruction syndrome (SOS). One patient developed posterior reversible leuko-encephalopathy syndrome (PRES) and one additional patient had tremors. The prevelance of these side-effects was similar to those reported for continuous i.v. administration. In all, 28% of the evaluable patients developed acute GVHDgrade II, though the incidence of severe (grade IIIIV) GVHD was only 7%. These results suggest that intermittent bolus i.v. tacrolimus administration is a safe and effective method of GVHD prophylaxis in children.