Discussion
The Peg-GCSF has a longer half-life requiring a one-time administration
as compared to conventional recombinant human GCSF which has a short
half-life and hence requiring daily administration. This makes it more
tolerable and acceptable for children (7-9). Peg-GCSF also provides a
sustained drug level as compared to pulse like levels with GCSF which is
more effective for PBSC mobilization (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 mobilization in adults. There is paucity of
literature of successful use of Peg-GCSF and its appropriate dosing for
PBSC mobilization in children. From the meagre published data, we can
draw conclusion that it is non-inferior to conventional GCSF with regard
to efficacy and safety (1,6,15,16). We have described here our
experience of PBSC mobilization with Peg-GCSF in 9 children. Our
patients received chemotherapy followed by Peg-GCSF and we found in our
cohort a fairly uniform and predictable time to CD34 peak from start of
chemotherapy and from the administration of Peg-GCSF. Also, we were able
to harvest the desired CD34 stem cell dose in single harvest procedure
for all our patients including the ones with relapsed malignancies who
were heavily pretreated and hence deemed poor mobilisers. None of our
patients had any major adverse event. All our patients who received
autologous HSCT had a brisk and robust engraftment.
Fritsch et al. have reported a similar successful and safe harvest
experience among their patient cohort which comprised of first time
diagnosed solid tumor patients as well as relapsed cases. Also, no other
adverse events except leukocytosis had been observed in all their
patients (1). The side effect of leukocytosis was lower in those who
received Peg-GCSF because Peg-GCSF has a predominant neutrophil mediated
elimination and hence its clearance is self-regulating (1,7). Dallorso
et al found a success rate of ~77% for PBSC
mobilization with single dose of 100mcg/kg of Peg-GCSF. They also found
that CD34 cell levels more than 20/microliter were first observed in the
peripheral blood at a median of 6 days after Peg-GCSF administration and
they remained sustained above 20/microliter for a median of 6 days. This
points to another appealing aspect of Peg-GCSF that it provides a wider
temporal window for planning harvest in case the peak is apparently
likely to coincide with a holiday (15). Merlin et al reported a success
of 60% with peg-GCSF. Target dose of 5 million/kg stem cells could be
collected with a single apheresis procedure in only 16 out of 26
children despite using higher dose of peg-GCSF 300 microgram/kg (16). In
our cohort, PBSC could be harvested successfully in 100% of patients
with a single apheresis procedure. We used lower dose of peg-GCSF 100
microgram/kg in all our patients. Lowest dose of stem cell collected in
our cohort was 4 million/kg.
Peg-GCSF can circumvent the concerns of daily painful GCSF injections
thereby improving the compliance and making the entire experience of
autologous hematopoietic stem cell harvest more tolerable for children.
Our experience highlights that its feasible and safe to mobilise PBSC
with peg-GCSF in children with cancer.
Disclosure – All authors have nothing to declare. All authors
have contributed to this manuscript. DT wrote manuscript, AT collected
data, SP-Collected data, GA-collected data, RK-reviewed literature, NR-
reviewed literature, SY-wrote manuscript