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.