Aplastic Anemia |
From the Division of Pediatric Hematology and Oncology, Department of Pediatrics and Adolescent Medicine, University of Freiburg, Germany (AY, AF, PN, CN); Institute of Pathology, Klinikum Bayreuth, Germany (IB); Department of Pediatric Hematology and Oncology, Dr von Haunersches Kinderspital, Children Hospital of the Ludwig-Maximilians-University of Munich, Munich, Germany (MF); University Childrens Hospital, University of Zürich, Switzerland (EB); Department of Pediatric Oncology, Hematology and Immunology, University of Düsseldorf, Düsseldorf, Germany (UG); Department for Pediatric Hematology/Oncology, Hannover Medical School, Hannover, Germany (K-WS); University Childrens Hospital, University of Frankfurt, Germany (TK); Department of Pediatric Hematology and Oncology, Olgaspital, Stuttgart, Germany (UG-W); Erasmus University Medical Center-Sophia Children's Hospital, Rotterdam, The Netherlands (MMvdH-E).
Correspondence: Charlotte M Niemeyer M.D., Department of Pediatrics and Adolescent Medicine, Division of Pediatric Hematology and Oncology, University of Freiburg, Mathildenstrasse 1, 79106 Freiburg, Germany. E-mail: charlotte.niemeyer{at}uniklinik-freiburg.de
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Key words: myelodysplastic syndrome, refractory cytopenia, immunosuppressive therapy, anti-thymocyte globulin, children.
Refractory cytopenia (RC) is the most common subtype of myelodysplastic syndrome (MDS) in children.1 In pediatric patients, the term RC is used instead of refractory anemia, since anemia is not always present.2,3 Karyotype has a strong impact on outcome in RC.2 Patients with monosomy 7 have a significantly higher risk of progression to advanced MDS than have patients with other chromosomal abnormalities or a normal karyotype. It has been suggested that autoimmunity contributes to the cytopenia of MDS, and there is a pathological overlap between aplastic anemia and hypoplastic MDS.4–7 This concept led to the application of immunosuppressive therapy (IST) with antithymocyte globulin and/or cyclosporine A in adult MDS patients.8,9 Since the role of IST in children with RC is unknown, we report the results of IST in selected children with RC.
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Thirty-two children, who were initially diagnosed with RC in Germany (n=31) and Switzerland (n=1) were given IST as the first therapeutic intervention. One patient was excluded from the analysis because he was later diagnosed as having dyskeratosis _ongenital. The diagnosis of RC was confirmed in the other 31 children by central review of bone marrow and peripheral blood smears and bone marrow biopsies by one of us (IB).3,10 At least bilineage morphological myelodysplasia was necessary for the diagnosis of RC. Fanconis anemia was excluded by the chromosomal fragility test.
Patients characteristics
The median age at diagnosis was 10.1 (1.8–17.2) years. The median neutrophil count at IST was 0.6 (0.07–1.3)x109/L. All patients were transfusion-dependent for platelets and 29/31 for red cells. Bone marrow cellularity was decreased for age in all patients. Standard metaphase cytogenetic analysis revealed a normal karyotype in 13 patients and an abnormal karyotype in one patient (47,XY,–2,+2mar). Interestingly, this abnormality was no longer detected after IST. In 17 patients, cytogenetic analyses failed because of insufficient metaphases; in 13 of these 17 patients, monosomy 7 and trisomy 8 could be excluded by fluorescence in situ hybridization (FISH).
Immunosuppressive therapy
IST was given according to the protocol of study SAA 94 of the German/Austrian/Swiss Pediatric Aplastic Anemia Working Group.11 It included antithymocyte globulin (horse: 0.75 mL/kg body weight for 8 days; Sangstat/Genzyme), cyclosporine A (5 mg/kg body weight, adjusted to blood levels (100–150 ng/mL by monoclonal assay or 200–400 ng/mL by polyclonal assay) until day >180, prednisolone (started at a dose of 1–2 mg/kg, tapered down from day 14 and stopped on day 28), and granulocyte colony-stimulating factor (5 µg/kg body weight until day 28) in cases of ANC <0.5x109/L.
Evaluation of response and statistic analysis
Response was evaluated by blood counts on day 112, at 6, 9, and 12 months, and every 6 months thereafter. A complete response was diagnosed in the presence of a hemoglobin level within the age-adjusted normal range, a platelet count > 150x109/L, and neutrophil count >1.5x109/L. A partial response was diagnosed in patients with transfusion independency, platelet count > 20x109/L, and neutrophil count > 0.5x109/L. No response was present when neither the partial response nor the complete response criteria were met. Death, acquisition of chromosomal abnormality, progression to advanced MDS, a second course of IST, HSCT, no response at 6 months, and conversion to no response from partial or complete response (relapse) were considered to indicate treatment failure.12 Overall survival was defined as the time from day 1 of treatment with IST to death or last follow-up. Failure-free survival was defined as the time from day 1 of treatment with IST to treatment failure or the last follow-up. The Kaplan-Meier method was used for survival analysis, and Fishers exact test to examine the significance of the relationship between response to IST and categorized factors. A non-parametric rank test (Mann-Whitney U-test) was applied to evaluate the difference in quantitative factors between the different groups in terms of the response to IST.
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Figure 1. Response to immunosuppressive therapy at day 112, after 6 months, and at the last follow up for 31 children with hypoplastic refractory cytopenia. CR: complete remission, PR: partial remission, NR: no response, HSCT: hematopoietic stem cell transplantation. Six patients underwent subsequent HSCT because of NR (n=4), progression to RAEB (n=1), and clonal evolution of monosomy 7 without disease progression (n=1).
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![]() View larger version (10K): [in a new window] [Download PPT slide] |
Figure 2. Overall survival and failure-free survival after immuno-suppressive therapy in 31 children with hypoplastic refractory cytopenia. Death, acquisition of chromosomal abnormality, progression to advanced MDS, second course of IST, HSCT, no response at 6 months, and conversion to no response from partial or complete response were considered treatment failure. OS: overall survival, FFS: failure-free survival.
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This study shows that some children with hypoplastic RC respond to IST and recover hematopoesis, suggesting that the immune system plays a key role in the pathogenesis of the bone marrow failure in RC. However, the results should be interpreted with caution, because the patients enrolled represent a selected group of children with RC with hypoplastic bone marrow, no apparent cytogenetic abnormalities (with the exception of one patient), and a relatively short duration of disease, all of which may be favorable predictive factors for a response to IST. Moreover, the observational period of this study was short, and the long-term outcome remains unknown. A relevant limitation of the study is that conventional cytogenetic analysis failed in more than half of the patients.
The therapeutic aim in childhood MDS is a cure and not palliation. Children with MDS treated with IST have a high risk of relapse and progression to advanced MDS, as illustrated in this cohort. At the same time, HSCT in RC results in a cure rate of approximately 80%.2 To avoid late complications, such as growth failure and infertility, preparative regimens with reduced intensity have been introduced.14 Because of the favorable outcome of HSCT,14 we suggest that IST should generally be applied only in patients with a low risk of disease progression, that is, in patients with hypocellular bone marrow, a normal karyotype, and a short duration of cytopenia. For patients with no response at 6 months we recommend HSCT if a 7/8 or 8/8 HLA antigen matched unrelated donor is available.
Molldrem et al. reported that IST non-responders among adult MDS patients have a high risk of disease progression.8 Similarly, Kojima et al. noted that no response to IST at 6 months is a risk factor for secondary MDS in children with aplastic anemia.15 Since the results of HSCT from matched unrelated donors have become comparable to those from matched sibling donors,14 it is reasonable to recommend that, in the presence of a suitable alternative donor, IST non-responders should proceed to HSCT.
To conclude, IST can be a promising treatment option in selected patients with hypoplastic RC, specifically in patients without a suitable donor. Further evaluation of the long-term outcome after IST in comparison to HSCT is necessary to establish the most appropriate treatment strategy for children with RC.
CN designed the study in co-operation with MF. AF was responsible for the data management. AY and CN contributed to the analysis and interpretation of the results and writing the manuscript draft. PN was responsible for the statistical analyses. CN, EB, UG, KWS, TK, and UGW recruited patients in the data base. MHE revised the paper critically for important intellectual content. IB was responsible for the morphological central review of the bone marrow of the enrolled patients. The manuscript was approved by all authors.
The authors reported no potential conflicts of interest.
Funding: this work was supported by the Alexander von Humboldt-Stiftung, Bonn, Germany.
Received for publication August 22, 2006. Accepted for publication January 25, 2007.
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