Delayed introduction of G-CSF after chemotherapy does not affect peripheral blood stem cell yield and engraftment kinetics in children with high-risk malignancies: retrospective study of 45 cases.

We retrospectively compared the effects of two time points of G-CSF (Filgrastim) introduction for PBSC mobilization in 45 children with different malignancies. Seventeen patients received the first G-CSF dose on day 2 or 3 following chemotherapy (group 1). Twenty-eight patients received a "flexible" G-CSF injection schedule when the G-GSF was started at the time of the first platelet count rise during post-chemotherapy recovery phase (group 2). Leukapheresis was performed when WBC recovery reached >2.0 x 10(9)/l or if the peripheral blood CD34(+) cell level was >0.01 x 10(9)/l. A median of 2 (1-4) leukapheresis procedures was performed in both groups to yield a median of 4.2 and 6.1 x 10(6) CD34(+) cells/kg in groups 1 and 2, respectively, which was generally sufficient for auto-transplantation. The proportion of patients with a failure of PBSC collection was similar and G-CSF consumption estimated through the total cycle dose was 2.3 times less in group 2 without increasing infectious risks. The short-term hematological recovery and the early post-transplant course were similar in the two groups. Delayed introduction of G-CSF after chemotherapy allowed PBSC harvest equivalent to that obtained after early G-CSF introduction. This approach could be an interesting alternative in PBSC mobilization but should be assessed by a prospective controlled study.