Comparative genomic hybridization detects many recurrent imbalances in central nervous system primitive neuroectodermal tumours in children

A series of 23 children with primitive neuroectodermal tumours (PNET) were analysed with comparative genomic hybridization (CGH). Multiple chromosomal imbalances have been detected in 20 patients. The most frequently involved chromosome was chromosome 17, with a gain of 17q (11 cases) and loss of 17p (eight cases). Further recurrent copy number changes were detected. Extra copies of chromosome 7 were present in nine patients and gains of 1q were detected in six patients. A moderate genomic amplification was detected in one patient, involving two sites on 3p and the whole 12p. Losses were more frequent, and especially involved the chromosomes 11 (nine cases), 10q (eight cases), 8 (six cases), X (six patients) and 3 (five cases), and part of chromosome 9 (five cases). These recurrent chromosomal changes may highlight locations of novel genes with an important role in the development and/or progression of PNET. © 1999 Cancer Research Campaig

No topoisomerase I alteration in a neuroblastoma model with in vivo acquired resistance to irinotecan

CPT-11 (irinotecan) is a DNA-topoisomerase I inhibitor with preclinical activity against neuroblastoma (NB) xenografts. The aim was to establish in vivo an NB xenograft resistant to CPT-11 in order to study the resistance mechanisms acquired in a therapeutic setting. IGR-NB8 is an immature NB xenograft with MYCN amplification and 1p deletion, which is sensitive to CPT-11. Athymic mice bearing advanced-stage subcutaneous tumours were treated with CPT-11 (27 mg kg−1 day−1 × 5) every 21 days (1 cycle) for a maximum of four cycles. After tumour regrowth, a new in vivo passage was performed and the CPT-11 treatment was repeated. After the third passage, a resistant xenograft was obtained (IGRNB8-R). The tumour growth delay (TGD) was reduced from 115 at passage 1 to 40 at passage 4 and no complete or partial regression was observed. After further exposure to the drug, up to 28 passages, the resistant xenograft was definitively established with a TGD from 17 at passage 28. Resistant tumours reverted to sensitive tumours after 15 passages without treatment. IGR-NB8-R remained sensitive to cyclophosphamide and cisplatin and cross-resistance was observed with the topoisomerase I inhibitor topotecan. No quantitative or qualitative topoisomerase I modifications were observed. The level of expression of multidrug resistance 1 (MDR1), MDR-associated protein 1 (MRP1) and, breast cancer resistance protein, three members of the ATP-binding cassette transporter family was not modified over passages. Our results suggest a novel resistance mechanism, probably not involving the mechanisms usually observed in vitro

Busulphan is active against neuroblastoma and medulloblastoma xenografts in athymic mice at clinically achievable plasma drug concentrations

High-dose busulphan-containing chemotherapy regimens have shown high response rates in children with relapsed or refractory neuroblastoma, Ewing's sarcoma and medulloblastoma. However, the anti-tumour activity of busulfan as a single agent remains to be defined, and this was evaluated in athymic mice bearing advanced stage subcutaneous paediatric solid tumour xenografts. Because busulphan is highly insoluble in water, the use of several vehicles for enteral and parenteral administration was first investigated in terms of pharmacokinetics and toxicity. The highest bioavailability was obtained with busulphan in DMSO administered i.p. When busulphan was suspended in carboxymethylcellulose and given orally or i.p., the bioavailability was poor. Then, in the therapeutic experiments, busulphan in DMSO was administered i.p. on days 0 and 4. At the maximum tolerated total dose (50 mg kg−1), busulphan induced a significant tumour growth delay, ranging from 12 to 34 days in the three neuroblastomas evaluated and in one out of three medulloblastomas. At a dose level above the maximum tolerated dose, busulphan induced complete and partial tumour regressions. Busulphan was inactive in a peripheral primitive neuroectodermal tumour (PNET) xenograft. When busulphan pharmacokinetics in mice and humans were considered, the estimated systemic exposure at the therapeutically active dose in mice (113 μg h ml−1) was close to the mean total systemic exposure in children receiving high-dose busulphan (102.4 μg h ml−1). In conclusion, busulphan displayed a significant anti-tumour activity in neuroblastoma and medulloblastoma xenografts at plasma drug concentrations which can be achieved clinically in children receiving high-dose busulphan-containing regimens. 1999 Cancer Research Campaig

Dermatofibrosarcoma protuberans, giant cell fibroblastoma, and hybrid lesions in children: clinicopathologic comparative analysis of 28 cases with molecular data--a study from the French Federation of Cancer Centers Sarcoma Group

The clinicopathologic and immunohistochemical features of 28 dermatofibrosarcoma protuberans (DFSP), giant cell fibroblastomas (GCFs), and hybrid lesions occurring in children are presented, including molecular data for seven of them. There were 19 pure adult-type DFSP (9 male and 10 female patients aged between a few days [neonate] and 13 years, median 7 years), 5 pure GCF (all males aged from 2 to 8 years, median 4 years), and 4 hybrid tumors (all males aged from 1 to 4 years, median 2.5 years). Tumor locations in pure adult-type DFSP included the trunk (6) and lower (11) and upper (2) limbs. Pure GCFs were observed on the trunk (4) and knee (1), and hybrid lesions on the trunk (2) and lower (1) and upper (1) extremities. Tumor size (n = 20) ranged from 0.6 to 5 cm (median 2 cm). Histologically, pure DFSP presented as monotonous and infiltrative, low-grade, dermal/hypodermal storiform spindle cell proliferations, sparing adnexal structures. GCF showed a dense fibrous to myxoid matrix containing slender wavy spindle cells and multinucleated giant stromal cells often lining angiectoid spaces. Hybrid lesions showed varying combinations of DFSP and GCF areas. Mitotic activity ranged from 1 to 3 mitoses per 10 high power fields. All tumors were diffusely positive for vimentin and CD34 but negative for smooth muscle actin, desmin, epithelial membrane antigen, and cytokeratins; one pure adult-type DFSP was also S-100 protein positive; <1% of nuclei were Ki67 (Mib-1) positive. One karyotyped adult-type DFSP showed an unbalanced t(17;22) (q22;q13) translocation. Multiplex RT-PCR analysis and sequencing of PCR products in seven cases showed gene fusion transcripts in two pure DFSP, two pure GCFs, and one hybrid lesion. Results were uncertain in one pure GCF; one adult-type DFSP was negative. Treatment procedures were known for 27 patients, consisting of 16 wide excisions and 11 marginal excisions. Follow-up information on 15 widely excised tumors (median 24 months; range 5-144 months) showed no recurrence. Five of six marginally excised lesions with available follow up recurred 2 months to 6 years (median 2 years) after initial surgery; all but one were cured by wide reexcision. None of the tumors metastasized. In conclusion, this study emphasizes 1) the occurrence of adult-type DFSP in children, 2) the close relationship between DFSP and GCF clinically, histologically, and molecularly, 3) the excellent prognostic of these lesions if widely excised, and 4) the diagnostic usefulness of RT-PCR analyses in detecting the gene fusion transcripts resulting from the t(17;22) (q22;q13) in paraffin-embedded tissue

Translocation-positive Low-grade Fibromyxoid Sarcoma: Clinicopathologic and Molecular Analysis of a Series Expanding the Morphologic Spectrum and Suggesting Potential Relationship to Sclerosing Epithelioid Fibrosarcoma: A Study From the French Sarcoma Group

Low-grade fibromyxoid sarcomas (LGFMS) bear either the t(7,16) (q32-34;p11) or t(11,16) (p11;p11) translocations, resulting in FUS-CREB3L2 or FUS-CREB3L1 fusions, respectively. Heretofore, fusion transcripts were mainly detected in frozen tissues, using reverse transcription-polymerase chain reaction. In this study, we aimed to develop a reliable method to detect these in paraffin-embedded tissues, and to examine the clinicopathologic characteristics of a series of translocation-positive LGFMS. Sixty-three neoplasms with typical morphologic features of LGFMS and 66 non-LGFMS tumors selected for their resemblance to LGFMS (LGFMS-like tumors) were examined. RNA of sufficient quality could be extracted from 111/129 (86%) cases (59 LGFMS, 52 non-LGFMS). Of all, 48/59 (sensitivity, 81%) LGFMS contained detectable transcripts (45 FUS-CREB3L2, 3 FUS-CREB3L1). Most relevant clinicopathologic features of fusion-positive LGFMS included predominance in lower extremities (22/48; thigh: 13/48), deep situation (46/48), and occasional presence of unusual histologic features, for example, hypercellular areas (16/48), foci of epithelioid cells (13/48), and giant rosettes (6/48). Most tumors expressed EMA (41/45), at least focally, CD99 (38/41) and bcl-2 (36/41) while being essentially negative for CD34 (2/45), mdm2 (1/41), smooth muscle actin (1/45), S100 protein (0/46), desmin (0/44), h-caldesmon (0/42), keratins (0/44), and CD117 (0/40). Eleven presumed LGFMS were fusion negative. Of all, 7/52 non-LGMFS neoplasms contained FUS-CREB3L2 transcripts, of which 4 had been diagnosed as sclerosing epithelioid fibrosarcoma. In conclusion, FUS-CREB3L1/L2 fusion transcripts can be detected in paraffin-embedded LGFMS in a sensitive manner, using reverse transcription-polymerase chain reaction. Most fusion-positive LGFMS are EMA-positive and CD34/S100/smooth muscle actin negative. The presence of epithelioid cells and fusion transcripts in both LGFMS and a subset of sclerosing epithelioid fibrosarcoma suggest that these neoplasms might be relate

Rhabdomyosarcoma: value of myogenin expression analysis and molecular testing in diagnosing the alveolar subtype: an analysis of 109 paraffin-embedded specimens

BACKGROUND: Identification of the alveolar subtype of rhabdomyosarcoma (ARMS) is important, because the poor prognosis associated with this subtype necessitates a modified therapeutic regimen. At present, ARMS diagnoses are made on the basis of histologic findings and the extent of myogenin immunopositivity. Nonetheless, the absence of an alveolar pattern in the solid variant, the low degree of differentiation in certain embryonal rhabdomyosarcomas (ERMS), and the increasing use of microbiopsy samples make the diagnosis of ARMS somewhat difficult. Two specific translocations have been found in ARMS, and fusion transcripts can be detected by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of paraffin-embedded tissue (PET). METHODS: To assess the value of myogenin staining and molecular testing in the diagnosis of rhabdomyosarcoma, the authors examined 109 rhabdomyosarcoma samples (45 ARMS samples and 64 ERMS samples). Real-time RT-PCR analysis of PET was performed in all 109 rhabdomyosarcomas, and RT-PCR analysis of frozen material was performed in 24 cases. RESULTS: PAX fusion transcripts were present in 44 cases (39 ARMS and 5 ERMS) and absent in 52 cases (2 ARMS and 50 ERMS). In 13 cases (4 ARMS and 9 ERMS), the results were not interpretable. Results were concordant between paired frozen and fixed tumor samples. All 35 interpretable ERMS samples that contained < 50% myogenin-positive cells failed to yield detectable PAX fusion transcripts. Of the 61 interpretable tumor samples (41 ARMS and 20 ERMS) that contained > 50% myogenin-positive cells, 44 (39 ARMS and 5 ERMS) yielded detectable PAX fusion transcripts. CONCLUSIONS: The current study demonstrates that molecular detection of PAX fusion transcripts via real-time RT-PCR analysis of PET is a sensitive and specific method for the diagnosis of ARMS and that immunohistochemical analysis of myogenin expression can be used to select cases for such molecular testing. Although RT-PCR analysis appears not to possess diagnostic value in tumors with < 50% tumor cell immunopositivity, it is strongly recommended for the diagnosis of tumors containing > 50% myogenin-positive cell