Sabine Stegmaier

Subtype and Prognostic Classification of Rhabdomyosarcoma by Immunohistochemistry

PURPOSE Rhabdomyosarcoma (RMS) is classified into two main subgroups: the embryonal (ERMS) and the alveolar (ARMS) form. The majority of the ARMSs are associated with specific chromosomal translocations (pARMS). Because ARMS is much more aggressive than ERMS, RMS subclassification has clinical relevance. However, diagnosis of RMS subgroups on the basis of histology or molecular biology can be difficult, and supplementing diagnostic methods would be desirable. The aim of this study was to establish a panel of markers for RMS subgroup classification by immunohistochemistry. MATERIALS AND METHODS Gene expression data were used for selection of subgroup-specific markers. Single sections of RMS with available expression data were used for establishment of the immunohistochemistry. Evaluation of the sensitivity and specificity of the markers was carried out using a tissue array representing 252 RMSs. Kaplan-Meier survival curves were calculated for determination of differences in overall survival of the different staining subgroups. RESULTS AP2beta and P-cadherin were selected as markers for pARMS, and epidermal growth factor receptor (EGFR) and fibrillin-2 as markers for ERMS. EGFR + fibrillin-2 detected ERMS with a specificity of 90% and with a sensitivity of 60%. AP2beta + P-cadherin detected pARMS with a specificity of 98% and a sensitivity of 64%, and allowed the detection of several misclassified tumors. The EGFR + fibrillin-2-positive group is associated with a favorable outcome, and the AP2beta + P-cadherin-positive group is associated with an unfavorable outcome. CONCLUSION The presented set of marker proteins detects RMS subgroups with high specificity and may be useful in routine subtype classification of RMS.

Microarray analysis of Ewing's sarcoma family of tumours reveals characteristic gene expression signatures associated with metastasis and resistance to chemotherapy

In Ewings sarcoma family of tumours (ESFT), the clinically most adverse prognostic parameters are the presence of tumour metastasis at time of diagnosis and poor response to neoadjuvant chemotherapy. To identify genes differentially regulated between metastatic and localised tumours, we analysed 27 ESFT specimens using Affymetrix microarrays. Functional annotation of differentially regulated genes revealed 29 over-represented pathways including PDGF, TP53, NOTCH, and WNT1-signalling. Regression of primary tumours (n=20) induced by polychemotherapy was found to be correlated with the expression of genes involved in angiogenesis, apoptosis, ubiquitin proteasome pathway, and PI3 kinase and p53 pathways. These findings could be confirmed by in vitro cytotoxicity assays. A set of 46 marker genes correctly classifies these 20 tumours as responding versus non-responding. We conclude that expression signatures of initial tumour biopsies can help to identify ESFT patients at high risk to develop tumour metastasis or to suffer from a therapy refractory cancer.

Prognostic value of PAX-FKHR fusion status in alveolar rhabdomyosarcoma: a report from the cooperative soft tissue sarcoma study group (CWS).

Alveolar Rhabdomyosarcomas (RMA) are characterized by chromosomal translocations, fusing the PAX3 or PAX7 gene with FKHR in about 85%. Previous studies have suggested that the fusion type is associated with prognosis. In order to investigate the predictive value of the PAX–FKHR fusion status on disease outcome of patients with RMA treated in the CWS trials we performed a retrospective analysis.

Heterogeneity of the MYCN Oncogene in Neuroblastoma

Purpose:MYCN amplification is an important therapy-stratifying marker in neuroblastoma. Fluorescence in situ hybridization with signal detection on the single-cell level allows a critical judgement of MYCN intratumoral heterogeneity. Experimental Design: The MYCN status was investigated by fluorescence in situ hybridization at diagnosis and relapse. Heterogeneity was defined as the simultaneous presence of amplified cells (≥5 cells per slide) and nonamplified cells within one tumor or sequential change of the amplification status during the course of the disease. Likewise, heterogeneity can be detected between primary tumor and metastasis. Results: From 1,341 patients analyzed, 1,071 showed no amplification, 250 showed homogeneous amplification, and 20 patients showed MYCN heterogeneity. Of the patients with heterogeneity, 12 of 20 had clusters of MYCN amplifications, 3 of 20 had amplified single cells, 3 of 20 showed MYCN amplifications in the bone marrow but not in the primary tumor, and 2 of 20 acquired MYCN amplification during the course of the disease. All stage 4 patients were treated according to high-risk protocols; 7 of 8 later progressed. Four patients with localized disease were treated according to high-risk protocol because of MYCN-amplified clusters; 1 of 4 later progressed. One patient treated with mild chemotherapy experienced progression. Seven patients with localized/4S disease underwent no chemotherapy: 4 of 5 patients with MYCN heterogeneity at diagnosis remained disease-free, and 1 of 5 experienced local progression. Two patients had normal MYCN status at diagnosis but acquired MYCN amplification during the course of the disease. Conclusion:MYCN heterogeneity is rare. Our results suggest that small amounts of MYCN-amplified cells are not correlated to adverse outcomes. More patients with heterogeneity are warranted to clarify the role of MYCN heterogeneity for risk classification.

PAX3-FKHR AND PAX7-FKHR FUSION GENES IMPACT OUTCOME OF ALVEOLAR RHABDOMYOSARCOMA IN CHILDREN

Rhabdomyosarcoma is a highly malignant embryonic tumor of childhood. Two specific translocations t(2;13)(q35;q14) and t(1;13)(p36;q14) have been identified in about 75–80% of ARMS cells. The aim of this multicenter study was to analyze the relationships between the identified fusion transcripts and survival including some selected clinical parameters. The extent of disease was graded according to clinical staging system with following distribution: 3 children with stage I, 4 with stage II, 23 with stage III, and 18 with stage IV spread disease having distant metastases. PAX3-FKHR fusion genes were detected in 28 and PAX7-FKHR fusion genes in 7 tumor biopsy specimens. Children with PAX3-FKHR fusion gene had often distant metastases at presentation (p = 0.03). PAX3-FKHR positive patients with locoregional disease had significantly poorer outcome compared with the ones with PAX7-FKHR positive tumors (p = 0.04). Although analyzed groups were small, significant differences in survival and clinical characteristics between PAX3-FKHR and PAX7-FKHR positive tumors were stated indicating their role in carcinogenesis. In addition, fusion gene analysis is a helpful tool in differential diagnosis of poorly differentiated soft tissue tumors.

The prognostic impact of SYT-SSX fusion type and histological grade in pediatric patients with synovial sarcoma treated according to the CWS (Cooperative Weichteilsarkom Studie) trials.

The aim of our analysis was the evaluation of the prognostic impact of SYT‐SSX fusion status and histological grading in synovial sarcoma (SS) of children and adolescents in the context of the consistent multimodal treatment strategy of the CWS (Cooperative Weichteilsarkom Studie; Cooperative Soft Tissue Sarcoma Study Group) and in comparison with other risk factors.

Questionable Universal Validity of PAX3/FOXO1 Fusion Gene Status As Molecular Marker for Improvement of Risk Stratification in Rhabdomyosarcoma Therapy

port networks for emancipated minors versus those still living with their parents, physician and patient adherence to protocol therapy, and the use of different chemotherapy regimens. The current C10403 trial conducted by the US adult cooperative groups is a critical study, which we support fully. However, the adult cooperative groups have not yet demonstratedthatequivalentresults tothoseobtainedinpediatrictrialscanbe obtained for older adolescents. Hence, we stand by our recommendation that the optimal treatment for an older adolescent with ALL is referral to a pediatric center and enrollment onto a pediatric group cooperative trial.