Allogeneic stem cell transplantation for pediatric and adolescent patients with CML: results from the prospective trial CML-paed I.

PURPOSE: Stem cell transplantation (SCT) can definitely cure chronic myeloid leukemia (CML), a rare disease in childhood. We prospectively evaluated the results of early SCT in pediatric CML after standardized pretreatment with hydroxyurea+/-interferon. PATIENTS AND METHODS: Between 1995 and 2004, 200 children (median age: 12.4 years) were enrolled and stratified: given the availability of an HLA-matched related donor (MRD), SCT was scheduled within 6 months and otherwise from an unrelated donor (UD) within 12 months following diagnosis. RESULTS: 176 patients underwent SCT; from MRD within median 4 months and from UD within median 11 months after diagnosis. At SCT, 158 patients were in chronic phase (CP1 or CP2), 9 patients were in accelerated phase and 9 patients were in blast crisis (BC). The conditioning regimen - total body irradiation or busulfan - exerted no different impact on overall survival (OS). Probability of OS at 5 years was 87+/-11% if grafted from a sibling (n=41), 52+/-9% from matched UD (MUD, n=71), and 45+/-16% from mismatched donors (MMD, n=55), respectively. A trend for better OS in CP1 was observed if SCT was performed within 6 months (n=49; 74+/-9%), compared to 7-12 months (n=52; 62+/-15%), and >12 months (n=43; 62+/-17%) after diagnosis, respectively (p=0.157). Probability of relapse at 5 years was 20+/-12%. Transplant-related mortality and graft-versus-host disease mainly contributed to the inferior outcome in UD and HLA-mismatched SCT. CONCLUSION: These data from the first prospective trial on CML restricted to children and adolescents might be considered for decision making when balancing the risks of SCT against the increasing use of imatinib as upfront treatment for CML.

[MRI screening before stem cell transplantation--necessary?]. / MRT-Untersuchung des Neurokraniums vor Stammzelltransplantation--notwendig oder überflüssig?

PURPOSE: In the context of stem cell transplantation (SCT), we often observe neurological complications as a consequence of immune system suppression, conditioning therapy or prophylaxis and treatment of graft-versus-host disease. Furthermore, cerebral lesions in existence prior to transplantation can be found. The aim of this study was to evaluate the benefit of cerebral magnetic resonance imaging (MRI) prior to stem cell transplantation. PATIENTS AND METHOD: Cerebral MR examinations of 116 children and adolescents were performed before SCT. Patients ranged in age from 1.1 to 21.4 years (mean 12.6 years). All MR images were obtained by a 1.5 T system. The predefined short protocol included an axial T 1-weighted SE sequence and a coronary T 2-weighted TSE sequence. We evaluated existing cerebral lesions, the diameter of the ventricular system, and the paranasal sinuses. In the case of pathological findings, the short examination protocol was expanded. RESULTS: In 5 of 116 children (4.3 %) we observed prior to SCT findings requiring immediate treatment although the patients did not show any clinical symptoms (1 x aspergilloma, 1 x hemorrhage of vascular anomaly). An increased risk of bleeding caused by cavernoma or another vascular anomaly without hemorrhage also had to be taken into account. 32 of 116 patients (37.1 %) showed atrophic lesions. In 42 children (36.2 %), we observed affections of the paranasal sinuses. CONCLUSION: The imaging findings requiring immediate treatment even though the children did not show any clinical signs, justify cerebral MR examinations prior to stem cell transplantation.

Reduced intensity conditioning in unrelated donor transplantation for refractory cytopenia in childhood.

Myelodysplastic syndromes (MDS) are a heterogenous group of acquired hematopoietic stem cell disorders. Refractory cytopenia (RC) is the most common subtype of childhood MDS and hematopoietic stem cell transplantation (HSCT) is the only curative treatment. HSCT following a myeloablative preparative regimen is associated with a low probability of relapse and considerable transplant-related mortality. In the present European Working Groups of MDS pilot study, we investigated whether a reduced intensity conditioning regimen (RIC) is able to offer reduced toxicity without increased rates of graft failure or relapse. Nineteen children with RC were transplanted from an unrelated donor following RIC consisting of fludarabine, thiotepa and anti-thymocyte globulin. Three patients experienced graft failure. Neutrophil and platelet engraftment occurred at a median time of 23 and 30 days, respectively. Cumulative incidence of grade II-IV and grade III and IV acute graft-versus-host disease (GVHD) was 0.48 and 0.13, respectively; three patients developed extensive chronic GVHD. Although infections were the predominant complications, only one patient with extensive chronic GVHD died from infectious complications. Overall and event-free survival at 3 years were 0.84 and 0.74, respectively. In conclusion, our results were comparable to those of patients treated with myeloablative HSCT. Long-term follow-up is needed to demonstrate the expected reduction in long-term sequelae.

Impact of cumulative anthracycline dose, preparative regimen and chronic graft-versus-host disease on pulmonary and cardiac function in children 5 years after allogeneic hematopoietic stem cell transplantation: a prospective evaluation on behalf of the EBMT Pediatric Diseases and Late Effects Working Parties.

This prospective study focused on risk factors and clinical outcome of pulmonary and cardiac late effects after allogeneic hematopoietic stem cell transplantation (allo-HSCT). We prospectively evaluated 162 children by pulmonary function tests (PFTs) and cardiac shortening fraction (SF) before allo-HSCT and yearly up to the 5th year of follow-up. The 5-year cumulative incidence of lung and cardiac impairment was 35 (hazard rate=0.03) and 26% (hazard rate=0.06), respectively. Patients presenting abnormal PFTs and SF at last follow-up were 19 and 13%, respectively, with a median Lansky performance status of 90% (70-100). Chronic graft-versus-host disease (c-GVHD) was the major risk factor for reduced lung function in univariate (P=0.02) and multivariate analysis (P=0.02). Total body irradiation (TBI) alone and TBI together with pre-transplant anthracycline administration were significant risk factors for reduced cardiac function in univariate analysis, only (P=0.04 and 0.004, respectively). In conclusion, our prospective study demonstrates an asymptomatic post-allo-HSCT deterioration of pulmonary and cardiac function in some long-term survivors, who had been transplanted in childhood, and thus emphasizes the need for lifelong cardiopulmonary monitoring and the development of new strategies both to reduce pre-transplant cardiotoxic regimens and to treat more efficiently c-GVHD.

Relapse, not regimen-related toxicity, was the major cause of treatment failure in 11 children with Down syndrome undergoing haematopoietic stem cell transplantation for acute leukaemia.

We report a retrospective analysis of 11 children with Down syndrome (DS) treated by SCT in eight German/Austrian SCT centres. Indications for transplantation were acute lymphoblastic leukaemia (N=8) and acute myeloid leukaemia (N=3). A reduced intensity conditioning (RIC) containing 2 Gy TBI was given to two patients, another five received a myeloablative regimen with 12 Gy TBI. Treosulphan or busulphan was used in the remaining four children. Four of eleven (36%) patients are alive. All of them were treated with a myeloablative regimen. One of the four surviving children relapsed 9 months after SCT and is currently receiving palliative outpatient treatment. The main cause of death was relapse (5/11). Two children died of regimen-related toxicity (RRT), one from severe exfoliative dermatitis and multiorgan failure after a treosulphan-containing regimen, the other from GvHD-related infections after RIC. Acute GvHD of the skin was observed in 10 of 10 evaluable patients, and chronic GvHD in 4 of 8. Our data show that DS patients can tolerate commonly used, fully myeloablative preparative regimens. The major cause of death is relapse rather than RRT resulting in an event-free survival of 18% and over all survival of 36%.

Elevated serum insulin-like growth factor binding protein-2 is associated with a high relapse risk after hematopoietic stem cell transplantation in childhood AML.

Insulin-like growth factor binding protein (IGFBP)-2 has mitogenic effects in normal and neoplastic cells. The purpose of this study is to examine the diagnostic and prognostic significance of elevated IGFBP-2 levels in children with AML after hematopoietic stem cell transplantation (HSCT) at relapse and continuous complete remission (CCR). In 27 children with AML (mean age 13.6+/-5.3 years; patients in remission n=15 with relapse n=12) serum parameters of IGFBP-2, IGFBP-3, IGF-I and IGF-II were analyzed up to 18 months after HSCT by RIA. AML-patients with evidence of relapse demonstrated a continuous increase of IGFBP-2 levels during the follow-up. At day 100 after HSCT, IGFBP-2 concentrations were significantly higher in patients with relapse than in children without relapse (7.4+/-4.0 standard deviation score (SDS) vs 3.9+/-1.7 SDS; P=0.01). Serum IGFBP-2 was identified as an independent factor for the prediction of relapse. Furthermore, the probability of relapse-free survival (RFS) in patients with IGFBP-2 >4.5 SDS at day 100 after HSCT was 31% compared to patients with IGFBP-2 <4.5 SDS was 72% (P=0.004). Patients with IGFBP-2 concentration up to 4.5 SDS more likely developed a relapse and had a poorer outcome. Identification of these patients allows a more individualized and aggressive adjuvant treatment and follow-up.

Donor leukocyte infusion after hematopoietic stem cell transplantation in patients with juvenile myelomonocytic leukemia.

Juvenile myelomonocytic leukemia (JMML) is a clonal myeloproliferative disorder of early childhood. In all, 21 patients with JMML who received donor leukocyte infusion (DLI) after allogeneic hematopoietic stem cell transplantation (HSCT) for either mixed chimerism (MC, n=7) or relapse (n=14) were studied. Six patients had been transplanted from an HLA-matched sibling and 15 from other donors. Six of the 21 patients (MC: 3/7 patients; relapse: 3/14 patients) responded to DLI. Response rate was significantly higher in patients receiving a higher total T-cell dose (> or =1 x 10(7)/kg) and in patients with an abnormal karyotype. None of the six patients receiving DLI from a matched sibling responded. Response was observed in five of six patients who did and in one of 15 children who did not develop acute graft-versus-host disease following DLI (P=0.01). The overall outcome was poor even for the responders. Only one of the responders is alive in remission, two relapsed, and three died of complications. In conclusion, this study shows that some cases of JMML may be sensitive to DLI, this providing evidence for a graft-versus-leukemia effect in JMML. Infusion of a high number of T cells, strategies to reduce toxicity, and cytoreduction prior to DLI may improve the results.

BCRP gene expression is associated with a poor response to remission induction therapy in childhood acute myeloid leukemia.

Breast cancer resistance protein (BCRP), also known as mitoxantrone resistance protein (MRX) or placenta ABC protein (ABC-P), is the second member of the ABCG subfamily of ABC transport proteins (gene symbol ABCG2). Transfection and enforced expression of BCRP in drug-sensitive cells confers resistance to mitoxantrone, doxorubicin, daunorubicin and topotecan. In this study the expression of BCRP gene was measured using TaqMan real-time PCR in 59 children with newly diagnosed AML. Nine patients were also analyzed in relapse. The median of BCRP gene expression was more than 10 times higher in patients who did not achieve remission after the first phase of chemotherapy (n = 24) as compared to patients who did achieve remission at this stage (n = 21; P = 0.012). In first relapse the expression of the BCRP gene was higher than at diagnosis (P = 0.038). Although high levels of BCRP gene expression were more frequent in subtypes of AML with a favorable prognosis, we found that within both risk groups (high and low risk), patients who expressed high levels of BCRP had a worse prognosis (P = 0.023). Our results strongly suggest that the expression of the BCRP gene reduces the response to chemotherapy in AML and that BCRP expression is higher at the time of relapse.

Vascular endothelial growth factor in newly diagnosed and recurrent childhood acute lymphoblastic leukemia as measured by real-time quantitative polymerase chain reaction.

PURPOSE: Overexpression of vascular endothelial growth factor (VEGF) is associated with increased angiogenesis, growth, and metastasis in solid tumors, but to date the significance of VEGF in leukemia has received only limited attention. Therefore, this study examined the cellular VEGF levels in 31 newly diagnosed and 22 recurrent cases of childhood acute lymphoblastic leukemia (ALL). EXPERIMENTAL DESIGN: VEGF was determined with real-time quantitative PCR methods. Kaplan-Meier statistical analyses were conducted for the relapse-free intervals and the overall survival times. The groups were compared by log-rank and rank-sum tests. RESULTS: The VEGF levels were significantly higher in recurrent ALL compared with newly diagnosed ALL (28.0 versus 3.1 units; P = 0.001). Kaplan-Meier estimates were conducted to analyze the prognostic value of VEGF levels in newly diagnosed ALL with regard to the relapse-free intervals and the overall survival times. In this analysis, the median relapse-free interval of patients with low VEGF levels was more than 10 years, whereas the relapse-free interval of patients with high VEGF expression was only 1.2 years. The median overall survival time for the collective with low VEGF levels was >10 years, whereas the survival of the group of patients with high VEGF levels was 3.9 years. This difference was not statistically significant. This may be attributable to the small number of patients involved. CONCLUSION: Our data suggest that VEGF may play an important role in the pathophysiology of ALL. The expression of VEGF raises the possibility of using angiogenesis inhibitors as a novel therapeutic strategy in childhood ALL.

Monoclonal antibodies against neuroblastoma. Production and preliminary characterization of their specificity.

Neuroblastoma (NB) is a common childhood tumor that originates from neuroblasts of the neural crest. In this paper we will describe the production of murine monoclonal antibodies (mAbs) to human NB cell lines. The hybridomas were selected by ELISA and immunofluorescence for antibody binding to multiple human neuroblastoma cultured cell lines, but not to hematopoietic cells and leukemic cells. The mAbs were characterized in terms of their ability to bind to human cell lines and tissues. The IgG2a and IgG2b mAbs may prove useful in the diagnosis of therapy of neuroblastoma.

Expression of CD34 and other haematopoietic antigens on neuroblastoma cells: consequences for autologous bone marrow and peripheral blood stem cell transplantation.

Autologous peripheral blood stem cells, obtained by CD34+ stem cell selection, are being used with increasing frequency for transplantation in patients with neuroblastoma. Here, we examined the surface membrane antigens of neuroblastoma cells with a panel of hematopoietic monoclonal antibodies (mAbs), including anti-CD34 mAbs, by flow cytometric analysis. We found stronger binding of anti-CD34 mAbs to clonogenic, less differentiated, non-adherent neuroblastoma cells than to adherent neuroblastoma cells. Moreover, the majority of neuroblastoma cell lines shared hematopoietic-associated antigens with all blood cells. Because of these cross-reactions, especially found with the anti-CD34 mAbs 12.8 and ICH3, we have demonstrated that there is a potential risk of cell harvest contamination by circulating neuroblastoma cells during CD34+ stem cell selection.

Neuroblastoma cells can express the hematopoietic progenitor cell antigen CD34 as detected at surface protein and mRNA level.

Recently, we have shown the expression of the hematopoietic precursor cell antigen CD34 on neuroblastoma cells. Here, we present the CD34 expression on 16 permanent neuroblastoma cell lines and primary cell lines at the mRNA level and the flow cytometric results on neuroblastoma cells grown in the same culture and split for flow cytometric analysis and total mRNA extraction. The flow cytometry was performed using a panel of anti-CD34 antibodies covering the epitope classes I to III. In eight neuroblastoma cell lines, CD34 mRNA expression could be detected and corresponded always with the protein surface expression. Alternatively, when CD34 mRNA expression was not seen, CD34 antigen expression ranged from negative to as high as 78%. Based on these results caution should be taken with transplants obtained by CD34+ stem cell selection from neuroblastoma patients.

Female twins with severe Christmas disease (hemophilia B).

Hemophilia B is an X-linked bleeding disorder. We report on female twins, who were conspicious in prolonged bleeding after venipuncture as well as hematomas after intramuscular injections even in the first months of their life. Their father suffering from a severe hemophilia B deceased in 1992. Their mother, half-brother and grandmother from their father's side had no signs of bleeding disorders. Clotting analysis performed in both twins revealed a markedly prolonged partial thromboplastin time (> 100 s). The factor IX levels were below 2%. In order to detect mutations, a general screen using the polymerase chain reaction (PCR) followed by single strand conformation polymorphism (SSCP) analysis of the PCR products have been performed. PCR products have been cut into smaller fragments using restriction endonucleases (RE) for an in-depth SSCP screen. A general screen for gross abnormalities in the factor IX gene including deletions, insertions and rearrangements was performed by Southern blot analysis of RE-digests of genomic DNA using the factor IX cDNA as a hybridization probe. Furthermore, we screened for mutations in the CG dinucleotides comprising part of RE-recognition sequences (exon 1, 2, 3, 4, 5, and 8). By all methods applied herein, no mutations have been detected in these twins. On the basis of our results the hemophilia B of these twins might be explained by extreme non-random lyonization.

Fatty acid composition of lymphocyte membrane phospholipids in children with acute leukemia.

The composition of phospholipid fatty acids (PLFA) of separated mononuclear blood cells (MNC) from patients with leukemia was established by high-resolution gas chromatography. Abnormal fatty acid concentrations are detected in the MNC membrane phospholipids in patients with acute lymphoblastic leukemia (ALL) without a deficiency of essential fatty acids (EFA). Significantly reduced relative levels of linoleic acid (4.35 vs. 7.82%; P<0.001) are found in the MNC-PL in patients with ALL as compared to a healthy control group. Moreover, the Delta6-desaturated fatty acids are increased: gamma-linoleic acid (3.56 vs. 0.17%; P<0.001), arachidonic acid (21.82 vs. 16.27%; P<0.05), docosatetraenoic acid (3.52 vs. 1.56%; P<0.001), docosapentaenoic acid (0.34 vs. 0.04%; P<0.001), octadecatetraenoic acid (0.53 vs. 0.23%; P<0.05), eicosatetraenoic acid (1.83 vs. 0.08%; P<0.001) and docosahexaenoic acid (2.77 vs. 1.54%; P<0.001). A increased Delta(6)-desaturase activity is postulated as the cause for the increased level of desaturate products or the increased Delta6-activity index (Ratio of gamma-linoleic acid+dihomogamma-linolenic acid to linoleic acid) (1.21 vs. 0.27; P<0.001). The Delta6-enzyme activities measured using linoleic acid and alpha-linoleic acid as substrate underscore these findings (Delta6(n-6); 2.49 vs. 0.65 and Delta6(n-3); 2.75 vs. 1.12 nmol x h(-1)/10(8) MNC). In contrast, patients with acute myeloid leukemia (AML) do not show any significant differences in the lymphocyte membrane PLFA and no Delta6-desaturase abnormalities.

Resistance factors and proliferative activity in childhood acute nonlymphoblastic leukemia.

Thirty-four children with newly diagnosed acute nonlymphoblastic leukemia were analysed for the expression of P-glycoprotein (P-170), glutathione S-transferase-pi, (GST-pi) topoisomerase II (Topo II) and the proliferation antigen Ki-67 by the streptavidin-biotin-peroxidase method. Overexpression of P-170 was present in 26 cases (76%) and GST-pi overexpression was seen in 11 patients (32%). Down regulation of Topo II was found in 16 patients (47%) and Ki-67 positive cells (>5%) were detectable in 9 patients (26%). The remission rate was not influenced by P-170 or GST-pi expression, whereas patients with down regulation of Topo II or low Ki-67 expression had lower remission rates. The data were not significant. The probability of continuous first remission (CR) was lower in patients with P-170 expression (p=0.09). A significantly lower probability of CR was also seen in patients with low proliferative activity (p=0.03, log-rank test). The expression of the resistance proteins and the proliferative activity were found to be independent of the clinical parameters age, sex, FAB-type, and initial white blood cell count.

Prognostic-significance of protein-kinase-C in newly-diagnosed childhood acute lymphoblastic-leukemia.

The expression of protein kinase C (PKC) was analysed in newly diagnosed cases of non-B acute lymphoblastic leukemia (NB-ALL) in children. Blast cells obtained from 104 children with untreated NB-ALL were analysed using the streptavidin-biotin-peroxidase method and the antibody MC5. Of the 104 patients with NB-ALL, 48 (=46%) showed positive staining for PKC. The relapse rate was significantly higher in NB-ALL with expression of PKC than in leukemia without expression of PKC (p=0.008). The relapse-free intervals in the PKC-negative leukemias were significantly longer than in cases of PKC-positive leukemias (p=0.004). The overall survival times were also longer in NB-ALL without expression of PKC than in ALL with PKC-expression (p=0.03). The results of univariate and multivariate analyses demonstrate that in addition to the clinical prognostic indicators PKC expression is a significant prognostic factor for relapse rate, relapse-free intervals, and overall survival times in NB-ALL of children.

Resistance-related proteins in initial and relapsed childhood acute lymphoblastic leukemia.

One hundred and eleven children with initial ALL and 28 children with relapsed ALL were analyzed immunohistochemically for expression of resistance-related proteins. P-glycoprotein (P-170) was found in 35% (initial ALL) vs 54% (relapsed ALL; p=0.07), glutathione S-transferase-pi (GST) in 49% vs 68% (p=0.07), thymidylate-synthase (TS) in 42% vs 64% (p=0.03), dihydrofolate-reductase (DHFR) in 20% vs 32% and metallothionein (MT) in 33% vs 32% of the cases. In initial ALL, the resistance proteins P-170 and GST were expressed more frequently in patients who relapsed under therapy and the frequency was similar to relapsed ALL. These results indicate that P-170 and GST-pi were already present before treatment. In contrast, expression of TS increased during treatment.

Detection of fos, jun and ras in newly-diagnosed childhood acute lymphoblastic-leukemia by immunocytochemistry and PCR.

The expression of the oncogenes c-fos, c-jun and c-pan-ras was analyzed at the protein level in newly diagnosed cases of acute lymphoblastic leukemia (ALL) in children. Blast cells obtained from 104 children with untreated ALL were determined by the streptavidin-biotin-peroxidase method and specific antibodies. Of the ALL 52 cases were positive for Fos (50%), 65 for Jun (63%), and 22 for Ras (21%). Fos-positive ALL had a significantly higher relapse frequency (p=0.0002). A similar trend was found for Jun-positive ALL (p=0.073). In contrast, the expression of Ras showed no significant correlation with the relapse rate (p=0.98). Corresponding results were obtained for the relapse-free intervals. The relapse-free intervals were higher in patients with Fos- and Jun-positive leukemic cells than in patients with negative tumor cells (Fos: p<0.001; Jun: p=0.09; Ras: p=NS, log-rank test). In order to substantiate the significant correlation of c-fos-protein expression with the relapse rate the c-fos-mRNA expression was investigated in a collective of 20 patients by semi-quantitative PCR. The PCR-assay and immunocytochemistry corresponded in 14 of 20 cases (70%). The results of the PCR-assay demonstrated also a trend for increased c-fos-mRNA expression and higher relapse rate.

Model experiments for immunomagnetic elimination of leukemic cells from human bone marrow. Presentation of a novel magnetic separation system.

Optimal conditions for removing leukemic cells from human bone marrow with monoclonal antibodies (mAb) and magnetic immunobeads were investigated. Monodisperse 3 microns polystyrene microspheres containing magnetite were coated with affinity-purified rabbit antimouse IgG at 4 degrees C, pH 9.6 for 18 h. SKW-3 cells (T-CLL cell line) were marked with the supravital DNA stain Hoechst 33342, seeded into normal human bone marrow, and then incubated with the mAb CD1, CD6, and CD8 at 4 degrees C for 30 min. In preliminary experiments REH cells (cALL cells) and mouse anti-REH cell antibodies were used to find the most favorable conditions for the binding of magnetic beads to tumor cells. Optimal formation of cell-bead rosettes was achieved by rotating beads and tumor cells together at room temperature at a concentration of 1 x 10(7) cells/ml, a bead: tumor cell ratio of 100:1 and an incubation time of one hour. The novel magnetic separation apparatus consists of three polystyrene chambers connected by silicone rubber tubing. The chambers contain four steel inserts each equipped with 32 nickel wires, which are magnetized by permanent magnets in such a way that the inhomogeneous high gradient magnetic field could be established within the cell suspension containing the cells to be depleted. The fluid flow was established by a peristaltic pump. At a flow rate of 1.5 ml/min and a field strength of 160 kA/m, no beads could be detected in the purged marrow. A cocktail of the three mAb was more effective than any single antibody in forming bead-cell rosettes. Two sequential purging cycles were superior to one. The marrow recovered was highly viable as assessed by trypan blue dye exclusion and by growth of CFU-GM.

Changes of serum growth factors (IGF-I,-II and IGFBP-2,-3) prior to and after stem cell transplantation in children with acute leukemia.

SUMMARY: Insulin-like growth factors (IGFs) and IGF-binding proteins (IGFBPs) may play an important role in tumor proliferation. This study aimed to investigate the IGF system in children with acute leukemia prior to and after hematological stem cell transplantation (HSCT). In 51 patients (AML n=27; ALL n=24; mean age 11.2+/-4.8 years), serum parameters (IGF-I,-II, IGFBP-2,-3) were investigated up to 18 months after HSCT by RIA. Patients with AML showed a significant increase of IGFBP-2 up to 100 days after HSCT (mean +/-s.d. prior to HSCT: 3.2+/-3.6 SDS vs 100 days after HSCT: 5.3 degrees +/-3.4 SDS, P=0.005). Furthermore, IGF-I and IGFBP-3 were significantly decreased (IGF-I: -0.3+/-1.5 vs -0.7 +/-1.2 SDS, P=0.001; IGFBP-3: -0.3+/-1.1 vs -1.0+/-1.1 SDS, P=0.02). Children with AML showed significantly higher IGFBP-2 (P=0.04) and significantly lower IGF-I (P=0.03) and IGFBP-3 (P=0.05) levels than children with ALL at day 100 after HSCT. We conclude that children with acute leukemia show important changes in the IGF system after HSCT. In particular, IGFBP-2 was significantly elevated at day 100 after HSCT. Increased IGFBP-2 and decreased IGF-I and IGFBP-3 may be associated with the increased proliferation rate of transplanted bone marrow.