Published online 23 December 2008
Haematologica, Vol 94, Issue 2, 302-304 doi:10.3324/haematol.2008.000216
Copyright © 2009 by Ferrata Storti Foundation
Stem Cell Transplantation |
HLA-identical umbilical cord blood transplantation from a sibling donor in juvenile myelomonocytic leukemia
Andrica C.H. de Vries1,
Robbert G.M. Bredius2,
Arjan C. Lankester2,
Marc Bierings3,
Monika Trebo4,
Petr Sedlacek5,
Charlotte M. Niemeyer6,
Marco Zecca7,
Franco Locatelli7,
Marry M. van den Heuvel-Eibrink1
1 Pediatric Oncology/Hematology, Erasmus Medical Center, Sophia Childrens Hospital, Rotterdam, The Netherlands
2 Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands
3 Department of Pediatric Hematology/Oncology, UMCU/Wilhelmina Childrens Hospital, Utrecht, The Netherlands
4 Department of Pediatrics, St Anna Childrens Hospital, Vienna, Austria
5 Department of Pediatric Hematology/Oncology, Charles University, University Hospital Motol, Prague, Czech Republic
6 Department of Pediatrics, University of Freiburg, Freiburg, Germany
7 Pediatric Hematology/Oncology, Fondazione IRCCS Policlinico San Matteo, University of Pavia, Italy
Correspondence: Marry M. van den Heuvel-Eibrink, MD, PhD, Department of Pediatric Oncology/Hematology, Sophia Childrens Hospital, Room Sp 2568, Dr. Molewaterplein 60, 3015 GJ Rotterdam, The Netherlands. Phone: international +31.10.7036691. Fax: international +31.10.7036801. E-mail:m.vandenheuvel{at}erasmusmc.nl
Key words: umbilical cord blood transplantation, HLA identical, JMML, children.
As recently described by Flotho et al. juvenile myelomonocytic leukemia (JMML) is a rare type of childhood leukemia not only characterized by young age, hepatosplenomegaly, thrombocytopenia and monocytosis, but also by molecular aberrations in the RAS-RAF-MEK-ERK signaling pathway and GM-CSF-hypersensitivity.1 Although progress has been made in unraveling the molecular background of JMML, the only curative treatment option for these children is stem cell transplantation (SCT).2,3 Previous studies have shown that in JMML the graft versus leukemia (GvL) effect of the SCT plays an important role in the prevention of relapse.2,4 Hence, donor and stem cell source selection could play an important role in the outcome of JMML patients. SCT using unrelated, immunological naive, umbilical cord blood (UCB) has shown to be effective for pediatric JMML.3 UCBT has increased the available pool of hematopoietic stem cell transplantation donors, especially for young children.5 This is important for patients with rare HLA-haplotypes and with diseases that may rapidly progress like JMML. However, it is conceivable that the relatively immunological naivety of cord blood stem cells from a newborn HLA identical sibling donor may be a negative factor for outcome.4,6
In this report we describe 5 JMML patients registered in the database of the European Working Group on Childhood MDS (EWOG-MDS), who have received umbilical cord stem cells from an HLA-identical sibling (Table 1). So far only MacMillan et al. has described a JMML patient who received HLA-identical sibling umbilical cord cells.7 More information is available on unrelated UCBT in JMML.3,7,8 Recently, from the combined EWOG-MDS/EBMT registry, Locatelli et al. described 100 JMML patients of whom 7 received an unrelated UCBT. These 7 patients showed a delayed hematologic recovery, but the outcome was comparable to the children treated with other stem cell sources.3 Rocha et al. reported that children receiving a related UCBT for malignancies, bone marrow failure syndromes, hemoglobinopathies, inborn errors of metabolism or immunodeficiencies, had a slower hematopoietic recovery and a lower risk of acute and chronic GVHD than children receiving a related bone marrow transplantation.9 Gluckman et al. have shown that the amount of acute GVHD in related UCBT is lower (18%) than in unrelated UCBT (32%).10 These studies underscore the relative immune naivety of the UCB cells and the feasibility of the use of UCBs especially for childhood transplantation settings. However, especially in JMML, where the GvL-effect is an important contributor to the success of the transplantation procedure, it could be questioned whether these relatively naive umbilical stem cells from sibling donors should be used in all patients, especially when alternative donors would be available.
In all cases full donor-chimerism was found after transplantation.
In the cases that relapsed, a mixed chimerism was found prior
to clinical progression. In addition, in Patient 1 increasing
mixed donor-chimerism developed from day 42 onwards without
clinical signs of relapse (
Figure 1). Mixed donor-chimerism
after SCT in JMML has been shown to be an important predictor
for relapse, therefore discontinuation of immunosuppressive
therapy (IST) is the first step to prevent relapse if this occurs
early after transplantation.
11 To avoid relapse, a second stem
cell transplantation was considered, but the parents were very
reluctant to proceed, because of the absence of any clinical
signs of JMML and the excellent clinical condition of the child.
Therefore, 6-mercaptopurine (6-MP) (average dose 40 mg/m
2) was
started on day 145 after SCT. When, after initial improvement,
donor-chimerism increased, 6-MP was replaced by 13-cisretinoic
acid (100 mg/m
2/day every other week) for 2.5 years until the
age of five years. Thereafter, the child remained well with
a current follow-up of five years after SCT. At present the
percentage of donor cells is 15%, without any clinical sign
of JMML. At the moment no series are available on the use of
6-MP and 13-cis-retinoic acid in a relapse setting after SCT
for JMML. Although Locatelli
et al. showed that second SCT was
successful in 7/15 cases with a relapse after SCT, the issue
whether to proceed to a second SCT in all cases of mixed donor-chimerism
without any clinical signs of JMML has not been clarifed.
3
We conclude that in JMML umbilical cord stem cells can be considered
a good alternative source for HSCT. However, whether the use
of sibling HLA-identical UCB should be advocated needs to be
confirmed in larger series of JMML patients.

Acknowledgments
Prof. Dr. P.D. Emanuel for his expert advise on he management
of Patient 1; dr. C.P. Kratz for performing the mutation analysis
of the JMML patients.

Footnotes
Funding: the scientific work of ACHdV is supported by a grant
from the KIKA Foundation, Amstelveen, The Netherlands.

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