Christine Devalck

Genetic heterogeneity of neuroblastoma studied by comparative genomic hybridization

Comparative genomic hybridization (CGH) analysis was performed on 36 neuroblastomas of both low and high stage of disease. This study significantly increases the number of neuroblastoma tumors studied by CGH. Analysis of larger series of tumors is particularly important in view of the different clinical subgroups that are recognized for this tumor. The present data and a comparison with all published CGH data on neuroblastoma provide further insights into the genetic heterogeneity of neuroblastoma. Stage 1, 2, and 4S tumors showed predominantly whole chromosome gains and losses. A similar pattern of whole chromosome imbalances, although less frequent, was observed in stage 3 and 4 tumors, in addition to partial chromosome gains and losses. An increase in chromosome 17 or 17q copy number was observed in 81% of tumors. The most frequent losses, either through partial or whole chromosome underrepresentation, were observed for 1p (25%), 3p (25%), 4p (14%), 9p (19%), 11q (28%), and 14q (31%). The presence of 3p, 11q or 14q deletions defines a genetic subset of neuroblastomas and contributes to the further genetic characterization of stage 3 and 4 tumors without MYCN amplification (MNA) and 1p deletion. The present study also provides additional evidence for a possible role of genes at 11q13 in neuroblastoma. In a few cases, 1p deletion or MNA detected by FISH or Southern blotting was not found by CGH, indicating that the use of a second, independent technique for evaluation of these genetic parameters is recommended. Genes Chromosomes Cancer 23:141–152, 1998.

Alveolar soft‐part sarcoma: Further evidence by FISH for the involvement of chromosome band 17q25

A cytogenetic study of an alveolar soft‐part sarcoma, a rare tumor of probably myogenic origin, demonstrated a t(X;17)(p11;q25) as the sole chromosomal abnormality. Dual‐ and triple‐color fluorescence in situ hybridization, performed on metaphase and interphase cells, confirmed the translocation between chromosomes X and 17 and demonstrated that this translocation resulted in loss of 17q25. Involvement of 17q25 has been described in four previously published cases of alveolar soft‐part sarcoma, but without further characterization. Compared to our karyotype, it seems that the derivative chromosome 17 observed in the reported cases could also be the result of a t(X;17) with possible loss of the 17q25 band. If so, a 17q25 deletion and/or chromosome rearrangement between Xp and 17q leading either to a gene fusion or gene disruption could play an important role in the pathogenesis of alveolar soft‐part sarcoma. Genes Chromosomes Cancer 23:194–197, 1998.

ArrayCGH-based classification of neuroblastoma into genomic subgroups†

High‐resolution array comparative genomic hybridization (arrayCGH) profiling was performed on 75 primary tumors and 29 cell lines to gain further insight into the genetic heterogeneity of neuroblastoma and to refine genomic subclassification. Using a novel data‐mining strategy, three major and two minor genomic subclasses were delineated. Eighty‐three percent of tumors could be assigned to the three major genomic subclasses, corresponding to the three known clinically and biologically relevant subsets in neuroblastoma. The remaining subclasses represented (1) tumors with no/few copy number alterations or an atypical pattern of aberrations and (2) tumors with 11q13 amplification. Inspection of individual arrayCGH profiles showed that recurrent genomic imbalances were not exclusively associated with a specific subclass. Of particular notice were tumors with numerical imbalances typically observed in subtype 1 neuroblastoma, in association with genomic features of subtype 2A or 2B. A search for prognostically relevant genomic alterations disclosed 1q gain as a predictive marker for therapy failure within the group of subtype 2A and 2B tumors. In cell lines, a high incidence of 6q loss was observed, with a 3.87–5.32 Mb region of common loss within 6q25.1–6q25.2. Our study clearly illustrates the importance of genomic profiling in relation to tumor behavior in neuroblastoma. We propose that genome‐wide assessment of copy number alterations should ideally be included in the genetic workup of neuroblastoma. Further multicentric studies on large tumor series are warranted in order to improve therapeutic stratification in conjunction with other features such as age at diagnosis, tumor stage, and gene expression signatures.

Survival among children and adults with sickle cell disease in Belgium: Benefit from hydroxyurea treatment.

To evaluate the survival of patients with sickle cell disease (SCD) recorded in the Belgian SCD Registry and to assess the impact of disease‐modifying treatments (DMT).

Haematopoietic stem cell transplantation for severe sickle cell disease in childhood: a single centre experience of 50 patients

Despite improvements in medical management, sickle cell disease (SCD) remains associated with severe morbidity and decreased survival. Allogeneic haematopoietic stem cell transplantation (HSCT) remains the only curative approach. We report the outcome of 50 consecutive children with severe SCD that received HSCT in our unit between November 1988 and April 2013. The stem cell source was bone marrow (n = 39), cord blood (n = 3), bone marrow and cord blood (n = 7) and peripheral blood stem cells (n = 1). All patients had ≥1 severe manifestation: 37 presented with recurrent vaso‐occlusive crises/acute chest syndrome, 27 cerebral vasculopathy and 1 nephropathy. The conditioning regimen consisted of busulfan + cyclophosphamide (BuCy) before November 1991 and BuCy + rabbit antithymocyte globulin after that date. Since 1995, all patients have been treated with hydroxycarbamide (HC) prior to transplantation for a median duration of 2·7 years. Median age at transplantation and median follow‐up was 8·3 and 7·7 years, respectively. Acute graft‐versus‐host disease (GVHD) and chronic GVHD were observed in 11 and 10 patients, respectively. An excellent outcome was achieved, with 8‐year overall survival and event‐free survival (EFS) rates of 94·1% and 85·6%, respectively. Since HC introduction, no graft failure occurred and EFS reached 97·4%. Prior treatment with HC may have contributed to successful engraftment.

Pituitary adenylate cyclase activating peptide and its receptors are expressed in human neuroblastomas

Vasoactive intestinal peptide (VIP) has been considered as an autocrine growth factor in neuroblastomas. Pituitary adenylate cyclase activating polypeptides (PA‐CAPs) are newly recognized members of the VIP family of neurohormones. As compared to VIP, PACAP has been reported to be biologically more potent and more efficient in tissues expressing selective PACAP receptors rather than common VIP/PACAP receptors. PACAPs and VIP interact with the same affinity and stimulate adenylate cyclase activity with the same efficacy and potency on the VIP receptors, but PACAPs act also on a more selective PACAP receptor that also recognizes VIP but with a 100‐ to 1,000‐fold lower affinity. Thus, depending on the type of receptors expressed at a cell surface, PACAP may be more potent and efficient than VIP. The capacity of 22 surgical specimens of neuroblastomas and of 5 established cell lines to synthesize PACAP and VIP and to synthesize and express PACAP receptors and VIP receptors was studied. Using the reverse transcriptase‐polymerase chain (RT‐PCR) method with specific primers, we detected the mRNAs coding for PACAP and VIP in 19 and 3 out of 22 samples, respectively. PACAP mRNA was expressed in 3 of the 5 cell lines studied and VIP mRNA in 4. Using the same techniques, PACAP and VIP receptors mRNA were detected in 21, and 13 of the 22 tumor samples and in 5 and 1 of the cell lines studied, respectively. The expression of the PACAP receptor was demonstrated by direct binding studies and/or by the relative potency of PACAPs and VIP to stimulate adenylate cyclase activity in 16 of the 22 tumors and in all the cell lines. In addition, there was no correlation between tumor stage and the expression of mRNA coding for the peptides and the receptors. The present results demonstrated that PACAP could also be a candidate as an autocrine regulator of neuroblastoma which a higher activity than VIP.

Children with sickle cell disease: growth and gonadal function after hematopoietic stem cell transplantation.

The aim of this study is to describe the growth, pubertal development, and gonadal function of a cohort of 30 sickle cell disease children who underwent bone marrow transplantation. They all received the standard pretransplant conditioning regimen of busulfan (14 or 16 mg/kg) and cyclophosphamide (200 mg/kg). Growth was normal both before and after transplant. Seven out of 10 girls had severe ovarian failure and requirement for estrogen replacement. Three out of 10 girls recovered some ovarian function posttransplant, with spontaneous pubertal development, menses, and 1 successful normal pregnancy. Follicle-stimulating hormone (FSH) serum levels were very high during spontaneous puberty and slowly normalized thereafter in these 3 patients. The 3 girls with ovarian function recovery differed from the 7 others by the lower busulphan dose of the conditioning regimen they received (14 rather than 16 mg/kg). All boys showed spontaneous pubertal development. However, most of them had small testis and elevated serum FSH levels, reflecting germinal epithelium damage. Testosterone level was low normal and luteinizing hormone elevated, reflecting Leydig cell insufficiency. In conclusion, 7/10 girls had complete gonadal failure and most of the boys had spontaneous puberty but germinal epithelial failure. Serum FSH levels showed important variations over time in the same patient.

Transplanted sickle-cell disease patients with autologous bone marrow recovery after graft failure develop increased levels of fetal haemoglobin which corrects disease severity

Summary. Bone marrow transplantation (BMT) is the only curative therapy for sickle‐cell disease (SCD), but is not devoid of failure risk. Nine patients with severe SCD were grafted in our institution between 1988 and 1993. Six patients successfully engrafted, but three failed to engraft and had delayed autologous recovery.

Hydroxyurea treatment for sickle cell disease: impact on haematopoietic stem cell transplantation's outcome

Summary:Since 1988, 24 children have undergone haematopoietic stem cell transplantation (HSCT) for severe sickle cell disease (SCD) in our unit, 13 being grafted after having been exposed to hydroxyurea (HU) to control SCD-related complications. Different pre-transplant conditioning regimens were given over time: Bu14/Cy200 in six patients (group 1), Bu16/Cy200/antithymocyte globulin (ATG) in five (group 2) and Bu16/Cy200/ATG with HU prior to HSCT in 13 (group 3). The aim of this study is to compare the outcome after HSCT of these groups of patients, which differ according to pre-transplant drug exposure. Overall, 20 of the 24 transplanted children had stable engraftment and have remained free of SCD-related symptoms after HSCT; 19 of them are currently alive and cured of SCD. In group 1 (HU−, ATG−), we observed one unexplainable late death, one absent engraftment, one late rejection and one mixed stable chimerism. In group 2 (HU−, ATG+), we observed the absence of engraftment in two patients and one early rejection. In group 3 (HU+, ATG+), we observed no cases of either absent engraftment, mixed stable chimerism or late rejection. In our experience, pre-transplant treatment with HU seems to be associated with a lower incidence of rejection/absent engraftment in severe SCD patients. These results need to be confirmed with a larger number of patients.

Granulocyte functions in children with cancer are differentially sensitive to the toxic effect of chemotherapy.

To analyze the toxicity associated to chemotherapy upon granulocytes, different functional assays were performed, within days of drug exposure and at time of bone marrow recovery, on polymorphonuclear neutrophils (PMN) from children with cancer. There were no significant postchemotherapy changes in the expression of the different receptors studied nor in the phagocytosis ofStaphylococcus aureus 42D. By contrast, a significant decrease was observed in H2O2 production in PMN recently exposed to chemotherapy with both cytofluorometric and chemiluminescence assays. There was also a decrease in the production of O[horizontal line over dot]2 and in chemotaxis; finally, the intracellular killing of S. aureus 42D andEscherichia coli was reduced. In patients having recovered from drug-induced bone marrow aplasia, PMN functions were found to be normal except for bactericidal activity which was still defective. These observations indicate that, in patients exposed to chemotherapy, some PMN functions are transiently altered, whereas microorganism cell killing is continuously impaired.