Introduction
High dose chemotherapy followed by Autologous hematopoietic stem cell transplant (HSCT) is a part of treatment regimens for many newly diagnosed and relapsed malignancies in children (1,2). These autologous HSCT are most commonly performed using peripheral blood stem cells (PBSC) (2-5). Various methods are known to be effective for PBSC mobilisation including chemotherapy combined with granulocyte-colony stimulating factor (GCSF) for these patients (2,3,5,6). The conventional recombinant human GCSF has a short half-life (~3.5 hours) and hence needs repeated administration which is quite painful for the child and also requires multiple hospital visits. The pegylated GCSF (Peg-GCSF) is a longer acting version of GCSF and has a half-life ranging from 15 to 80 hours after a subcutaneous injection (7-9).
Peg-GCSF is a covalent conjugate between the N-terminal methionyl residual of GCSF and mono-methoxy polyethylene glycol (Peg) moiety. Addition of Peg moiety to GCSF increases its molecular weight and size which results in decreased renal clearance by glomerular filtration. With this, the primary mode of elimination of Peg-GCSF remains to be neutrophil mediated clearance (7,8). Published studies have shown that a sustained low level of GCSF is better than short pulse-like level to mobilize PBSC. Hence, Peg-GCSF, might be superior to conventional GCSF in PBSC harvest in this aspect (9).
Most of the experience with Peg-GCSF comes from its use for prophylaxis and treatment of chemotherapy associated neutropenia in children and adults as well as for PBSC mobilisation in adults (9-14). There is paucity of literature of successful use of Peg-GCSF and its appropriate dosing for PBSC mobilisation in children (1,6,15-17). We report our experience of PBSC mobilisation with Peg-GCSF in 9 children.