Kinetics of peg-filgrastim after high-dose chemotherapy and autologous peripheral blood stem cell transplantation

Peg-filgrastim is a form of G-CSF with a sustained duration of action due to self-limited clearance. We administered 6 mg peg-filgrastim to 18 autograft recipients on day +1 after transplantation for hematologic malignancies. Plasma samples were collected at baseline and during transplantation. Hematopoietic recovery and clinical outcomes were compared to the historical data of 54 patients not receiving G-CSF. Patients receiving peg-filgrastim achieved a serum level of 115 000 pg/ml on day +2, 24 h after drug administration. Drug level maintained a plateau until day +8 and, after day +10, declined concomitantly with myeloid recovery. Patients experienced prompt neutrophil recovery: days +9 and +10 to 500 and 1000 neutrophils per microliter, and 4 days with an absolute neutrophil count <100 cells per microliter. Duration of antibiotic therapy was significantly shortened, but we did not observe significant differences in other end points. In conclusion, peg-filgrastim was well tolerated and efficacious, and hastened myeloid recovery.