The incidence and timing of leukocyte overshoot after pegfilgrastim administration

Pegfilgrastim is a PEGylated formulation of filgrastim with a long half-life. It is highly convenient and less burdensome for patients. However, white blood cell count may temporarily increase after administration; in particular, a leukocyte overshoot may be observed. The present study retrospectively examined the incidence and timing of leukocyte overshoot after pegfilgrastim administration. Fifty-five patients (118 occasions of pegfilgrastim) were evaluated. Leukocyte overshoot was defined as white blood cell count ≥10,000/mm3 exceeding the reference value. Leukocyte overshoot was observed in 71.2% (84/118) occasions, in 76.4% (42/55) patients. The maximum white blood cell count ≥30,000/mm3 was observed in 30.5% (36/118) occasions in 45.5% (25/55) patients and was observed in 39.3% (33/84) occasions on day 1 after pegfilgrastim administration and 26.2% (22/84) on day 2. Leukocyte overshoot has been observed in only 23.1% (9/39) patients administered with normal granulocyte colony-stimulating factor. However, there were no patients with white blood cell counts ≥30,000/mm3. There was a higher frequency of occurrence of leukocyte overshoot in response to pegfilgrastim than in response to normal granulocyte colony-stimulating factor. High incidence of leukocyte overshoot was observed when blood was collected 1–2 days after administration of pegfilgrastim. It is important for patients to understand the characteristics of pegfilgrastim by conducting pharmaceutical guidance