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V Combaret

Publications and source records attributed to V Combaret.

At least 19 recordsLinked to original sources
PubMed2003

Quality assessment of genetic markers used for therapy stratification.

PURPOSE: Therapy stratification based on genetic markers is becoming increasingly important, which makes commitment to the highest possible reliability of the involved markers mandatory. In neuroblastic tumors, amplification of the MYCN gene is an unequivocal marker that indicates aggressive tumor behavior and is consequently used for therapy stratification. To guarantee reliable and standardized quality of genetic features, a quality-assessment study was initiated by the European Neuroblastoma Quality Assessment (ENQUA; connected to International Society of Pediatric Oncology) Group. MATERIALS AND METHODS: One hundred thirty-seven coded specimens from 17 tumors were analyzed in 11 European national/regional reference laboratories using molecular techniques, in situ hybridization, and flow and image cytometry. Tumor samples with divergent results were re-evaluated. RESULTS: Three hundred fifty-two investigations were performed, which resulted in 23 divergent findings, 17 of which were judged as errors after re-evaluation. MYCN analyses determined by Southern blot and in situ hybridization led to 3.7% and 4% of errors, respectively. Tumor cell content was not indicated in 32% of the samples, and 11% of seemingly correct MYCN results were based on the investigation of normal cells (eg, Schwann cells). Thirty-eight investigations were considered nonassessable. CONCLUSION: This study demonstrated the importance of revealing the difficulties and limitations for each technique and problems in interpreting results, which are crucial for therapeutic decisions. Moreover, it led to the formulation of guidelines that are applicable to all kinds of tumors and that contain the standardization of techniques, including the exact determination of the tumor cell content. Finally, the group has developed a common terminology for molecular-genetic results.

Biomarkers, Tumor↗
PubMed2001

Comparative genomic hybridization (CGH) analysis of stage 4 neuroblastoma reveals high frequency of 11q deletion in tumors lacking MYCN amplification.

We have studied the occurrence and association of 11q deletions with other chromosomal imbalances in Stage 4 neuroblastomas. To this purpose we have performed comparative genomic hybridization (CGH) analysis on 50 Stage 4 neuroblastomas and these data were analyzed together with those from 33 previously published cases. We observed a high incidence of 11q deletion in Stage 4 neuroblastoma without MYCN amplification (59%) whereas 11q loss was only observed in 15% of neuroblastomas with MYCN-amplification (p = 0.0002) or 11% of cases with 1p deletion detected by CGH (p = 0.0001). In addition, 11q loss showed significant positive correlation with 3p loss (p = 0.0002). Event-free survival was poor and not significantly different for patients with or without 11q deletion. Our study provides further evidence that Stage 4 neuroblastomas with 11q deletions represent a distinct genetic subgroup that typically shows no MYCN-amplification nor 1p deletion. Moreover, it shows that neuroblastomas with 11q deletion also often present 3p deletion. This genetic subgroup shows a similar poor prognosis as MYCN amplified 4 neuroblastomas.

Adolescent↗
PubMed2001

Multicentre analysis of patterns of DNA gains and losses in 204 neuroblastoma tumors: how many genetic subgroups are there?

PROCEDURE: Analysis of comparative genomic hybridization (CGH) data of 120 tumors from four different studies, and data of 84 previously unpublishied tumors, allowed delineation of at least six different genetic subsets of neuroblastomas. RESULTS AND CONCLUSIONS: A small number of tumors show no detectable imballances. A second group of tumors presents with gains and losses of whole chromosomes and is found predominantly in prognostically favorable stage 1 and 2 tumors. The remaining groups are characterized by the presence of partial chromosome imbalances, and are found mostly in stage 3, 4, and 4S tumors. The third group shows 17q gain without 11q loss, 1p loss, or MYCN amplification (MNA). The fourth group has 1p deletion or MNA, and finally, a fifth group shows 11q loss without 1p deletion or MNA, and is found mainly in stage 4 tumors. The latter group is significantly associated with losses of 3p, 4p, and 14q.

Chromosome Aberrations↗
PubMed2001

Lack of antitumor activity of recombinant endostatin in a human neuroblastoma xenograft model.

Patients with metastatic neuroblastoma are rarely curable with currently available therapy, and the search for new treatment options, which include the use of inhibitors of tumor angiogenesis, is warranted. Here, we have evaluated the efficacy of one of the most promising natural inhibitors of angiogenesis described to date, endostatin, in a human neuroblastoma xenograft model in nude mice. Murine endostatin cDNA was cloned in a bacterial expression vector, expressed as a polyHis-Endostatin fusion protein and purified on Ni2+-NTA beads. The in vitro activity of soluble endostatin was confirmed on bovine capillary endothelial cells and human umbilical vein endothelial cells. The human neuroblastoma cell line SKNAS was injected subcutaneously in the flank of nude mice and administration of the recombinant angiogenesis inhibitor started when tumors reached the size of 100 microm3. Twenty mg/kg of recombinant precipitated endostatin or PBS was subcutaneously injected daily for 12 days. Serum endostatin levels were measured using a competitive enzyme immunoassay. Tumor growth was only slowed down in endostatin-treated mice when compared to control mice, and no statistically significant difference in serum levels of endostatin was observed between endostatin-treated and control groups. The lack of correlation between serum concentration and tumor response raises concern regarding the mechanism of action of endostatin.

Angiogenesis Inhibitors↗
PubMed2000

Assessment of percutaneous fine needle aspiration cytology as a technique to provide diagnostic and prognostic information in neuroblastoma.

The International Neuroblastoma Staging System (INSS) criteria for diagnosis requires an unequivocal pathological diagnosis and favours the identification of prognostic markers in the samples. Surgical biopsies of the primary tumour and bone marrow (BM) sampling in metastatic disease constitute the major sources of tumour material for the laboratory. We analysed the possibility of percutaneous fine needle aspiration cytology (FNAC) constituting an alternative procedure to the conventional technique of sampling of the primary tumour in children with advanced neuroblastoma. From July 1987 through July 1998, 64 consecutive children suspected of having advanced neuroblastoma and referred to our institution underwent percutaneous FNAC of deeply located tumours. FNAC was performed using 22-gauge needles under ultrasound guidance, before any chemotherapy and within the first days following admission. No complication occurred after FNAC. The median number of the extracted tumour cells was 2.3x10(6) (range: 0-40.6x10(6)). Cytology analysis was possible in 59/64 cases (92%) and immunocytochemistry in 56/64 (88%) allowing confirmation of the diagnosis. N-Myc analysis was available in 46/64 (72%). In addition, the presence of a partial deletion of chromosome 1p (del 1p) was assessed, since 1992, in 24/47 cases (51%), where enough cells were available. FNAC of deeply located advanced neuroblastoma is safe and information is available in a few hours after admission. The provided material is reliable for confirmation of diagnosis and analysis of biological prognostic markers in the majority of cases. More invasive tumour sampling procedures are required only in selected cases.

Adolescent↗
PubMed2000

LMCE3 treatment strategy: results in 99 consecutively diagnosed stage 4 neuroblastomas in children older than 1 year at diagnosis.

PURPOSE: To tailor postinduction therapy for stage 4 neuroblastoma in children who are older than 1 year at diagnosis according to status after induction. PATIENTS AND METHODS: From March 1987 to December 1992, 99 patients who were consecutively admitted were included in the Lyon-Marseille-Curie East of France (LMCE)3 strategy. After induction with the French Society of Pediatric Oncology NB87 regimen and surgery, patients who were in complete remission immediately proceeded to consolidation therapy with vincristine, melphalan, and fractionated total-body irradiation (VMT). All other patients underwent a postinduction strategy before VMT, either an additional megatherapy regimen or further chemotherapy with etoposide/carboplatin. RESULTS: The progression-free survival (PFS) is 29% at 7 years from diagnosis, which compares favorably with that of a similar cohort of 72 patients previously reported by our group (LMCE1; PFS of 20% at 5 years and 8% at 14 years, P =.004). In the multivariate analysis, only age younger than 3 years at diagnosis (P =.0085) and achievement of complete or very good partial remission after NB87 and surgery (P =.00024) remained significant. The PFS of the 87 patients who were included in the postinduction strategy was significantly better than that of the comparable 62 patients on the LMCE1 study (32% v 11% at 7 years; P =.005). CONCLUSION: The progressive improvements in the LMCE results over the last 10 years suggest that improvements in supportive care measures and increases in each component of this strategy (induction, postinduction, consolidation) may all contribute to increased survival rates.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1998

[Biological markers for the prognosis of neuroblastoma: proposal of a method of analysis].

The prognosis of pediatric neuroblastoma depends both on clinical presentation and on certain cellular and molecular characteristics. At the present time, two hypotheses can be drawn to explain both clinical and biological heterogeneity. In the first hypothesis, neuroblastoma progresses from early to late clinical stages through a classical multistep process linked to an accumulation of molecular abnormalities. In the second hypothesis, neuroblastoma represents an heterogeneous group of unrelated diseases, where most of stages I and II or stage IVS neuroblastomas can rather be considered as benign tumors, and stage IV neuroblastoma as a true malignant proliferation. To ascertain relevant biological factors for the prognosis of the disease, it is uppermost important that all investigators agree on biological criteria for analysis when neuroblastoma tissue is available in screened and unscreened populations. This paper reviews the biological tools available for prognosis in neuroblastoma, the priority for analysis of biological markers according to reliability, feasibility, and reproducibility of analysis procedure, and the conditions of tissue storage for further analysis of these biological markers. The standardized biological evaluation of neuroblastoma will allow, first, to collect sufficient data for multivariate analysis of prognostic factors and, second, to better define the putative links between various forms of the disease.

Biomarkers, Tumor↗
PubMed1997

Screening for neuroblastoma in France: methodological aspects and preliminary observations.

A pilot study of neuroblastoma mass screening was initiated in January 1990 in the Rhône French district. The expected number of births per year is 26,000. The study is designed for a 5-year period with three major goals: 1) measurement of the compliance rate of a voluntary test at 4 months of age; 2) evaluation of the technical value of high-pressure liquid chromatography (HPLC) as a screening method; and 3) detailed biological characterization of all detected tumors. 61,551 children were screened between May 1, 1990 and December 31, 1993. Participation was 69% in 1990, 81.5% in 1991, and over 83% in 1992. HPLC was a satisfactory assay method. The number of clinical examinations required for positive tests as defined in the protocol is 1 per 3,621 tests. The false positive rate is 1 per 3,583 tests. Eight neuroblastomas were discovered by-screening (one stage I, three stage II, one stage III, three stage IVs). All are alive and well but were good prognosis cases according to the main prognostic factors. Five patients were discovered before screening (so called Halo effect): one stage I, one stage III, three stage IVs. One died of disease and four are alive in complete remission after treatment. Two patients were false negative (one stage III with N-myc amplification, one stage IV with bad prognosis features) and three cases of neuroblastoma were missed because of noncompliance with the screening program. This pilot study concludes on the feasibility of a mass screening program in France. The estimated cumulative incidence of neuroblastoma at 3 years is 1 per 4,375 living births and overdiagnosis is probable. All the detected cases were of good prognosis and the false negative ones were poor prognosis cases.

Child, Preschool↗
PubMed1997

False positive MIBG scan.

The fortuitous discovery of a left posterior cervico-mediastinal mass during hospitalization for hemolytic anemia in an 18 month old baby is reported. Metaiodobenzylguanidine (MIBG) uptake suggested a sympathetic tissue origin of the mass despite negative catecholamines excretion, but histopathologic examination revealed a juvenile capillary angioma within a normal sympathic ganglion.

3-Iodobenzylguanidine↗
PubMed1997

Clinical relevance of CD44 cell surface expression and MYCN gene amplification in neuroblastoma.

This multicentric analysis of tumours obtained from 140 patients with neuroblastoma confirms that the lack of CD44 expression is a highly significant factor of poor prognosis and, as previously published in multivariate analysis of the four factors, i.e. MYCN amplification, CD44 expression, age and tumour stage, CD44 expression and tumour stage were the only independent prognostic factors of event-free survival (Combaret et al., J Clin Oncol 1996, 14, 25-34). Furthermore, CD44 analysis affords significant prognostic discrimination in subgroups of patients with or without MYCN amplified tumours, both in low-stage neuroblastomas and high-grade neuroblastomas. In the subgroup of patients with low-stage neuroblastoma and the stage 4 subgroup, CD44 was the only independent prognostic factor for the prediction of event-free survival in a multivariate analysis. In conclusion, CD44 is one of the most powerful factors for predicting clinical outcome in neuroblastoma at the time of initial staging.

Age Factors↗
PubMed1997

Loss of chromosome 1p may have a prognostic value in localised neuroblastoma: results of the French NBL 90 Study. Neuroblastoma Study Group of the Société Française d'Oncologie Pédiatrique (SFOP).

Between March 1990 and December 1994, 316 consecutive children with localised neuroblastoma were registered in the French NBL 90 study. In addition to the assessment of a new chemotherapy regimen in unresectable neuroblastoma, we evaluated the prognostic significance of MYCN amplification and loss of the short arm of chromosome 1 (LOH1p). MYCN was found in 22/225 children (10%) and associated with unfavourable clinical features such as age at diagnosis > 1 year and large and unresectable tumours. LOH1p was observed in 9/91 patients (10%), of whom some had favourable prognostic factors such as age at diagnosis < 1 year (n = 4), INSS stage 1 or 2 (n = 3) and no MYCN amplification (n = 4). Overall survival (OS) and event-free survival (EFS) were, respectively, 56% and 22% (median follow-up: 36 months) for children with LOH1p compared with 97% and 94% for those without (log-rank = 10(-8)). All except 1 of the 5 children with MYCN amplification and LOH1p relapsed and ultimately died of the disease. Among the 4 with LOH1p and no MYCN amplification, recurrence occurred in 3 (2 local, 1 metastatic), all alive in second remission after salvage therapy (12-19 months after the relapse). In multivariate analysis, LOH1p was the strongest prognostic indicator for subsequent relapse. LOH1p appears more discriminant than MYCN amplification for predicting the risk of recurrence in children with localised neuroblastoma. However, its analysis was possible in only 30% of our patients and its final impact on survival should be confirmed in larger, prospective studies in order to stratify subsequent treatment.

Abdominal Neoplasms↗
PubMed1997

Clinical relevance of TRKA expression on neuroblastoma: comparison with N-MYC amplification and CD44 expression.

TRKA expression was evaluated on 122 untreated neuroblastomas by immunohistochemistry using an antibody with predetermined specificity. This procedure is simple and reliable for protein detection at cellular level in a routine clinical setting. Fourteen tumours were classified as benign ganglioneuroma with a restricted expression of TRKA on ganglion cells; these patients were excluded from the following analysis. A total of 108 tumours were classified as neuroblastoma or ganglioneuroblastoma; 74 expressed TRKA protein, which strongly correlated with low stage, absence of N-MYC amplification, age (<1 year), CD44 expression and favourable clinical outcome. In a univariate analysis including tumour stage, age, histology, N-MYC amplification, CD44 and TRKA expression, all parameters had significant prognostic value. The absence of TRKA expression on CD44-positive or N-MYC non-amplified tumours permits the characterization of a subgroup of patients with intermediate prognosis. However, in a multivariate analysis taking into consideration the prognostic factors mentioned above, CD44 and tumour stage were the only independent prognostic factors for the prediction of patients' event-free survival.

Analysis of Variance↗
PubMed1997

In vitro targeting and specific transfection of human neuroblastoma cells by chCE7 antibody-mediated gene transfer.

We developed a new vector for gene targeting of neuroblastoma (NB) cells, based on the utilization o a monoclonal antibody (chCE7) covalently linked to polylysine (PL). In the presence of chloroquine, chCE7-PL-DNA complexes transfected NB cells as efficiently as DOTAP, transfectam, TF-X50, or lipofectamine. This was demonstrated by transfection of the luciferase or beta-galactosidase reporter genes in three different NB cell lines. This transfection was specific, since it was inhibited in the presence of competing unconjugated chCE7 antibody (Ab), and was not observed in cell lines negative for the CE7 antigen. We tested the potential biological activity of a plasmid coding for gamma-interferon (gamma IFN) transfected with chCE7-PL. HLA ABC expression on NB cells was induced after transfection with pCMV-gamma IFN at a higher level than after incubation with 1000 IU/ml of purified gamma IFN. Moreover, these HLA ABC-positive NB cells were able to activate autologous cytotoxic T lymphocytes in vitro. Thus chCE7-PL is able to target a plasmid to NB cells and to allow the expression of the transfected gene in a biologically active form.

Antibodies, Monoclonal↗
PubMed1996

A 5-year (1990-1994) neuroblastoma screening feasibility study in France. Methodology and preliminary observations.

INTRODUCTION: Following the pioneering Japanese experience, several European and North American groups implemented pilot studies on screening infants for neuroblastoma, considering the possibility of demonstrating a decrease in mortality rate. In France, a 5-year (1990-1994) feasibility study on neuroblastoma screening at the age of 4 months was initiated in the Rhône district (1.5 M inhabitants, 26,000 births per year). METHODS: Vanillylmandelic (VMA) and homovanillic (HVA) acids were measured by HPLC, and creatinine (Cr) by the Jaffé's kinetic method on Technicon RA-XT. VMA and HVA were expressed as microgram/mg of Cr. The method was assessed with both a daily intra-laboratory control and a sample of urine obtained from a national quality control organism. RESULTS AND DISCUSSION: The overall participation rate for the 5-year period was 82.2%. Out of 105,293 infants tested from 128,126 births, 12 NB cases were discovered with screening (screened cases) and 1 case was discovered with a late performed test (at 13 months of age). Six neuroblastomas were found clinically before the age of 4 m. Two cases were missed because the parents did not perform the test. Three children with normal tests at screening were false-negative cases: two of them were found secreting at diagnosis, while one remained non-secretory at diagnosis and later on. Otherwise, thirty-five false-positive tests were found. Biochemical observations are discussed. It is too early to reach clinical conclusions from this screening program on neuroblastomas as it is presently being followed up.

Chromatography, High Pressure Liquid↗
PubMed1996

Gangliosides protect human melanoma cells from ionizing radiation-induced clonogenic cell death.

With an experimental model of spontaneous lung metastases of melanoma developed in this laboratory, a range of sublines (variants and clones) with different metastatic potential and ganglioside expression was established from a single human melanoma cell line M4Be. Using an in vitro clonogenic assay and provided that cells were cultured for no more than five passages, variations in cellular radioresistance of M4Be and seven sublines derived from M4Be were detected. This study shows a positive correlation between the cell intrinsic radioresistance of M4Be and its seven sublines and their total ganglioside content. More precisely, the proportion of radioresistant cells in M4Be and the seven sublines correlated with the number of cells determined by flow cytometry that were positively labelled with a monoclonal antibody directed to GD3 disialoganglioside. Blocking the cellular biosynthesis of gangliosides with the inhibitor Fumonisin B1 or cleaving with Vibrio cholerae neuraminidase the cell surface ganglioside-bound sialic acid in a radioresistant poorly metastatic subline increased its radiosensitivity in vitro. In contrast, enrichment of a radiosensitive metastatic subline with exogenous bovine brain GM1 increased its radioresistance in vitro. These results suggest that, in the radiation dose range important for radioprotection (0-1 Gy), membrane gangliosides radioprotect human melanoma cells in vitro.

Animals↗
PubMed1996

Comparison of the diagnostic and prognostic value of biological markers in neuroblastoma. Proposal for a common methodology of analysis. SENSE group.

BACKGROUND: The prognosis of pediatric neuroblastoma depends both on clinical presentation and on certain cellular and molecular characteristics. Screening programs have been initiated in infants of less than one year of age, based on the hypothesis that neuroblastoma progresses from early to late clinical stages through a classical multistep process linked to an accumulation of molecular abnormalities. However, recent analyses suggest that most cases discovered by screening are low stage tumors considered as dysembryogenetic residues devoid from major abnormalities and that high-grade tumors with molecular abnormalities are unrelated diseases. AIM OF THE REVIEW: To confirm one or the other hypothesis, and eventually identify biological factors possibly responsible for the initiation and progression of the disease, it is of utmost importance that all investigators agree on biological criteria for analysis when neuroblastoma tissue is available in screened and unscreened populations. This paper reviews the biological tools available for prognosis in neuroblastoma, the priority for analysis of biological markers according to both methodological reliability and feasibility, and the conditions of tissue storage for further analysis of these biological markers. CONCLUSION: The standardized biological evaluation of neuroblastoma will allow to collect sufficient data for multivariate analysis; such analysis is now fundamental if one wants to clearly define the respective impacts of biological abnormalities on neuroblastoma progression.

Biomarkers, Tumor↗
PubMed1996

Clinical relevance of CD44 cell-surface expression and N-myc gene amplification in a multicentric analysis of 121 pediatric neuroblastomas.

PURPOSE: In contrast to other human tumors, a repression of the cell-surface glycoprotein CD44 on neuroblastoma is a marker of aggressiveness that usually correlates to N-myc amplification. We thus compared the prognostic value of both markers in the initial staging of 121 children treated for neuroblastoma in collaborative institutions. METHODS: Frozen samples were analyzed by a rapid and well-standardized technique of immunostaining with monoclonal antibodies (MoAbs) against epitopes in the CD44 constant region. RESULTS: In this retrospective series, CD44 was expressed on 102 specimens and strongly correlated with favorable tumor stages and histology, younger age, and normal N-myc copy numbers. In univariate analysis, CD44 expression and normal N-myc were the most powerful markers of favorable clinical outcome (P < 10(-6) and chi 2 = 65.40 and P < 10(-6) and chi 2 = 42.56, respectively), but analysis of CD44 affords significant prognostic discrimination in subgroups of patients with or without N-myc-amplified tumors. In the subgroup of stage IV neuroblastomas, CD44 was the only significant prognostic marker (P < .02, chi 2 = 5.76), whereas N-myc status was not discriminant. In multivariate analysis of five factors, ie, N-myc amplification, CD44 expression, age, tumor stage, and histology, the only independent prognostic factors of event-free survival were CD44 expression and tumor stage. CONCLUSION: The analysis of CD44 cell-surface expression must be recommended as an additional biologic marker in the initial staging of the disease.

Antibodies, Monoclonal↗