The first European interdisciplinary ewing sarcoma research summit

Synthesis and Evaluation of a Class of Compounds Inhibiting the Growth of Stromal Antigen 2 (STAG2)-Mutant Ewing Sarcoma Cells

STAG2 (SA2) is a critical component of the cohesin complex that regulates gene expression and the separation of sister chromatids in cells. Mutations in STAG2 have been identified in over thirty different types of cancers including non-small cell lung, bladder and Ewing sarcoma. Selectively inhibiting cancer cells lacking of STAG2 is an attractive approach for the cancer therapy. Here we report that a small molecule, StagX1, identified through a high-throughput screening, inhibits the growth of Ewing sarcoma cells possessing mutant STAG2 . A new synthetic route to the StagX1 scaffold and new versions of the molecule along with their activity in a cell viability assay are reported.

Does PAX7 and NKX2.2 immunoreactivity in Ewing sarcoma have prognostic significance?

Ewing sarcoma (ES) is an aggressive neoplasm with variable morphology. It has no specific immunoprofile or molecular signature. Neither CD99, NKX2.2 nor PAX7 immunoreactivity alone is completely specific, although diagnostic specificity improves when combined. The purpose of the present study was to investigate the immunohistochemical (IHC) expression of PAX7 in a large series of genetically confirmed ES. Existing results for CD99 and NKX2.2 immunoexpression, morphological findings and molecular studies (fusion gene subtypes) were retrieved from a previous study. Survival analyses were performed in cases with available clinical follow-up. PAX7 was positive in 95.5% of ES with diffuse staining (> 50%) in all positive cases and moderate or strong intensity for most cases. Nineteen ES displayed both PAX7 and CD99 immunoreactivity but lacked NKX2.2 immunoexpression. No relationships could be found between PAX7 expression and the histological types or ES gene fusion subtypes. Univariant/multivariate analysis showed that lack of PAX7 and/or NKX2.2 immunoexpression constitute independent poor prognostic factors for progression free survival (PFS) and overall survival (OS). In conclusion, IHC for CD99, NKX2.2, and PAX7 may be useful in daily practice for ES diagnosis, particularly in hospitals lacking facilities for molecular studies. In addition, the combination of strong CD99 membranous positivity and nuclear PAX7 and NKX2.2 immunoreactivity seems to be very reliable for ES diagnosis when supported by a corroborating histomorphologic and clinical picture. Although PAX7 is not entirely specific for ES, it seems to have a more extensive and strong nuclear immunoreactivity than NKX2.2 expression, even in tumors with decalcification artifact. Considering the prognostically significant data herein reported, we strongly recommend validation in prospective ES series that include localized and disseminated tumors.

ASB2 is a direct target of FLI1 that sustains NF-κB pathway activation in germinal center-derived diffuse large B-cell lymphoma

Background

Diffuse large B-cell lymphoma (DLBCL) comprises at least two main biologically distinct entities: germinal center B-cell (GCB) and activated B-cell (ABC) subtype. Albeit sharing common lesions, GCB and ABC DLBCL present subtype-specific oncogenic pathway perturbations. ABC DLBCL is typically characterized by a constitutively active NF-kB. However, the latter is seen in also 30% of GCB DLBCL. Another recurrent lesion in DLBCL is an 11q24.3 gain, associated with the overexpression of two ETS transcription factors, ETS1 and FLI1. Here, we showed that FLI1 is more expressed in GCB than ABC DLBCL and we characterized its transcriptional network.

Methods

Gene expression data were obtained from public datasets GSE98588, phs001444.v2.p1, GSE95013 and GSE10846. ChIP-Seq for FLI1 paired with transcriptome analysis (RNA-Seq) after FLI1 silencing (siRNAs) was performed. Sequencing was carried out using the NextSeq 500 (Illumina). Detection of peaks was done using HOMER (v2.6); differential expressed genes were identified using moderated t-test (limma R-package) and functionally annotated with g:Profiler. ChIP-Seq and RNA-Seq data from GCB DLBCL cell lines after FLI1 downregulation were integrated to identify putative direct targets of FLI1.

Results

Analysis of clinical DLBCL specimens showed that FLI1 gene was more frequently expressed at higher levels in GCB than in ABC DLBCL and its  protein levels were higher in GCB than in ABC DLBCL cell lines. Genes negatively regulated by FLI1 included tumor suppressor genes involved in negative regulation of cell cycle and hypoxia. Among positively regulated targets of FLI1, we found genes annotated for immune response, MYC targets, NF-κB and BCR signaling and NOTCH pathway genes. Of note, direct targets of FLI1 overlapped with genes regulated by ETS1, the other transcription factor gained at the 11q24.3 locus in DLBCL, suggesting a functional convergence within the ETS family. Positive targets of FLI1 included the NF-κB-associated ASB2, a putative essential gene for DLBCL cell survival. ASB2 gene downregulation was toxic in GCB DLBCL cell lines and induced NF-κB inhibition via downregulation of RelB and increased IκBα. Additionally, downregulation of FLI1, but not ASB2, caused reduction of NF-κB1 and RelA protein levels.

Conclusions

We conclude that FLI1 directly regulates a network of biologically crucial genes and processes in GCB DLBCL. FLI1 regulates both the classical NF-κB pathway at the transcriptional level, and the alternative NF-κB pathway, via ASB2. FLI1 and ASB2 inhibition represents a potential novel therapeutic approach for GCB DLBCL.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02159-3.

Therapeutic Potential of EWSR1-FLI1 Inactivation by CRISPR/Cas9 in Ewing Sarcoma

Simple Summary

Ewing sarcoma is an aggressive tumor with still unacceptable survival rates, particularly in patients with metastatic disease and for which it is necessary to develop new and innovative therapies. These tumors are characterized by the presence of chromosomal translocations that give rise to chimeric transcription factors (i.e., EWSR1–FLI1) that govern the oncogenic process. In this article, we describe an efficient strategy to permanently inactivate the EWSR1–FLI1 oncogene characteristic of Ewing sarcoma using CRISPR/Cas9 gene editing technology. Although the application of gene therapy in cancer still has many limitations, for example, the strategy for delivery, studies like ours show that gene therapy can be a promising alternative, particularly for those tumors that are highly dependent on a particular oncogene as is the case in Ewing sarcoma.

Abstract

Ewing sarcoma is an aggressive bone cancer affecting children and young adults. The main molecular hallmark of Ewing sarcoma are chromosomal translocations that produce chimeric oncogenic transcription factors, the most frequent of which is the aberrant transcription factor EWSR1–FLI1. Because this is the principal oncogenic driver of Ewing sarcoma, its inactivation should be the best therapeutic strategy to block tumor growth. In this study, we genetically inactivated EWSR1–FLI1 using CRISPR-Cas9 technology in order to cause permanent gene inactivation. We found that gene editing at the exon 9 of FLI1 was able to block cell proliferation drastically and induce senescence massively in the well-studied Ewing sarcoma cell line A673. In comparison with an extensively used cellular model of EWSR1–FLI1 knockdown (A673/TR/shEF), genetic inactivation was more effective, particularly in its capability to block cell proliferation. In summary, genetic inactivation of EWSR1–FLI1 in A673 Ewing sarcoma cells blocks cell proliferation and induces a senescence phenotype that could be exploited therapeutically. Although efficient and specific in vivo CRISPR-Cas9 editing still presents many challenges today, our data suggest that complete inactivation of EWSR1–FLI1 at the cell level should be considered a therapeutic approach to develop in the future.

Omic approaches to pediatric bone sarcomas

Over the last decade, next-generation sequencing technologies have improved our ability to assess biological aspects, at genomic and transcriptomic levels, on a large scale- and have been increasingly used for the management of adult cancers. However, their efficacy and feasibility within pediatrics is still under investigation. "Omic" approaches represent an opportunity to understand the oncogenic mechanisms driving the onset and progression of bone sarcoma and improve the clinical management of young patients with bone sarcomas. This review focuses on the current genomic and transcriptomic characteristics of managing pediatric patients, affected by Ewing sarcoma and osteosarcoma.

Catalytic inhibition of KDM1A in Ewing sarcoma is insufficient as a therapeutic strategy

BACKGROUND

Ewing sarcoma and desmoplastic small round cell tumors (DSRCT) are rare and clinically aggressive sarcomas usually characterized by oncogenic fusion proteins involving EWS. Emerging studies of Ewing sarcoma have demonstrated EWS-FLI1-driven chromatin remodeling as a key aspect of tumorigenicity. In particular, the lysine-specific demethylase KDM1A/LSD1 is linked to transcriptional regulation of target genes orchestrated by the EWS portion of the fusion protein interacting with repressive chromatin-remodeling complexes. Consistent with this model, depletion of KDM1A supports it is a molecular therapeutic target in Ewing sarcoma cells, but effective drugs need to be identified.

PROCEDURE

A comprehensive phenotypic analysis of the effects of catalytic KDM1A inhibitors ORY-1001 and GSK2879552, including clinically relevant doses, was carried out in 2D and 3D spheroid models of Ewing sarcoma and DSRCT.

RESULTS

Catalytic inhibition of KDM1A did not affect cell viability in 2D and 3D assays and had no impact on invasion in a 3D assay.

CONCLUSIONS

Overall, evidence presented here does not support inhibition of KDM1A catalytic demethylase activity as an effective therapeutic strategy for Ewing sarcoma or DSRCT. However, roles of KDM1A beyond its demethylase activity should be considered for these sarcomas.

Regorafenib regressed a doxorubicin-resistant Ewing's sarcoma in a patient-derived orthotopic xenograft (PDOX) nude mouse model

PURPOSE

Ewing's sarcoma (ES) is a rare and recalcitrant disease which is in need of a development of a novel effective therapy. The aim of this study was to investigate the efficacy of regorafenib on an ES tumor in a patient-derived orthotopic xenograft (PDOX) model.

METHODS

The ES PDOX models were established orthotopically in the right chest wall of nude mice to match the site of the tumor in the donor patient. The ES PDOX models were randomized into three groups (G) when the tumor volume reached 75 mm³: G1: untreated control; G2: doxorubicin (DOX) (i.p., 3 mg/kg, weekly, 2 weeks); G3: regorafenib (REG) (p.o., 30 mg/kg, daily, 2 weeks). Tumor volume and body weight were measured twice a week. All mice were sacrificed on day 15.

RESULTS

DOX was ineffective compared to the control group (P = 0.229). REG regressed the tumor size (P < 0.001 and P < 0.001, relative to control and DOX, respectively).

CONCLUSIONS

Our findings suggest that REG has clinical potential for ES patients whose tumors respond to REG in a PDOX model.

Comprehensive analysis of multi Ewing sarcoma microarray datasets identifies several prognosis biomarkers

Ewing sarcoma (ES) is a common primary malignancy in children and adolescents. Progression of treatment methods hasn't contributed a lot to the imrovement of prognosis. To identify potential prognostic biomarkers, a meta-analysis pipeline of multi-gene expression datasets for ES from the Gene Expression Omnibus (GEO) was performed. Three datasets were screened and differential expression genes (DEGs) in ES samples compared with normal tissues were identified through limma package and subjected to network analysis. As a result, 1,470 DEGs were obtained which were mainly involved in biological processes associated with immune response and transcription regulation. Network analysis obtained 22 core genes with high network degree and fold change. Kaplan-Meier analysis based on ES datasets from The Cancer Genome Atlas identified five genes, including glycogen phosphorylase, muscle-associated, myocyte-specific enhancer factor 2C, tripartite motif containing 63, budding uninhibited by benzimidazoses1 and Ras GTPase-activating protein 1, whose altered expression profiles are significantly associated with survival. Changes of their expression values were further confirmed through RT-qPCR in ES cell and normal cell lines. Those genes may be considered as potential prognostic biomarkers of ES and should be helpful for its early diagnosis and treatment.

Cell-to-cell heterogeneity of EWSR1-FLI1 activity determines proliferation/migration choices in Ewing sarcoma cells

Ewing sarcoma is characterized by the expression of the chimeric EWSR1-FLI1 transcription factor. Proteomic analyses indicate that the decrease of EWSR1-FLI1 expression leads to major changes in effectors of the dynamics of the actin cytoskeleton and the adhesion processes with a shift from cell-to-cell to cell-matrix adhesion. These changes are associated with a dramatic increase of in vivo cell migration and invasion potential. Importantly, EWSR1-FLI1 expression, evaluated by single-cell RT-ddPCR/immunofluorescence analyses, and activity, assessed by expression of EWSR1-FLI1 downstream targets, are heterogeneous in cell lines and in tumours and can fluctuate along time in a fully reversible process between EWSR1-FLI1^high states, characterized by highly active cell proliferation, and EWSR1-FLI1^low states where cells have a strong propensity to migrate, invade and metastasize. This new model of phenotypic plasticity proposes that the dynamic fluctuation of the expression level of a dominant oncogene is an intrinsic characteristic of its oncogenic potential.

The second European interdisciplinary Ewing sarcoma research summit--A joint effort to deconstructing the multiple layers of a complex disease

Despite multimodal treatment, long term outcome for patients with Ewing sarcoma is still poor. The second “European interdisciplinary Ewing sarcoma research summit” assembled a large group of scientific experts in the field to discuss their latest unpublished findings on the way to the identification of novel therapeutic targets and strategies. Ewing sarcoma is characterized by a quiet genome with presence of an EWSR1-ETS gene rearrangement as the only and defining genetic aberration. RNA-sequencing of recently described Ewing-like sarcomas with variant translocations identified them as biologically distinct diseases. Various presentations adressed mechanisms of EWS-ETS fusion protein activities with a focus on EWS-FLI1. Data were presented shedding light on the molecular underpinnings of genetic permissiveness to this disease uncovering interaction of EWS-FLI1 with recently discovered susceptibility loci. Epigenetic context as a consequence of the interaction between the oncoprotein, cell type, developmental stage, and tissue microenvironment emerged as dominant theme in the discussion of the molecular pathogenesis and inter- and intra-tumor heterogeneity of Ewing sarcoma, and the difficulty to generate animal models faithfully recapitulating the human disease. The problem of preclinical development of biologically targeted therapeutics was discussed and promising perspectives were offered from the study of novel in vitro models. Finally, it was concluded that in order to facilitate rapid pre-clinical and clinical development of novel therapies in Ewing sarcoma, the community needs a platform to maintain knowledge of unpublished results, systems and models used in drug testing and to continue the open dialogue initiated at the first two Ewing sarcoma summits.

Management of Ewing sarcoma family of tumors: Current scenario and unmet need

Ewing sarcoma family tumors (ESFT) are heterogeneous, aggressive group of disease with peak incidence in adolescent and young adults. The outcome has been improved dramatically from 10% with surgery and radiotherapy alone to 65%-70% now, in localized disease, with the introduction of chemotherapy. Chemotherapy regimen evolved from single agent to multiagent with effort of many cooperative clinical trials over decades. The usual treatment protocol include introduction of multi-agent chemotherapy in neoadjuvant setting to eradicate systemic disease with timely incorporation of surgery and/or radiotherapy as local treatment modality and further adjuvant chemotherapy to prevent recurrence. Risk adapted chemotherapy in neoadjuvant and adjuvant setting along with radiotherapy has been used in many international collaborative trials and has resulted in improved outcome, more so in patients with localized disease. The role of high dose chemotherapy with stem cell rescue is still debatable. The outcome of patients with metastatic disease is dismal with long term outcome ranges from 20%-40% depending on the sites of metastasis and intensity of treatment. There is a huge unmet need to improve outcome further, more so in metastatic setting. Novel therapy targeting the molecular pathways and pathogenesis of ESFT is very much required. Here we have discussed the current standard of management in patients with ESFT, investigational targeted or novel therapies along with future promises.

The Macrophage Inhibitor CNI-1493 Blocks Metastasis in a Mouse Model of Ewing Sarcoma through Inhibition of Extravasation

Metastatic Ewing Sarcoma carries a poor prognosis, and novel therapeutics to prevent and treat metastatic disease are greatly needed. Recent evidence demonstrates that tumor-associated macrophages in Ewing Sarcoma are associated with more advanced disease. While some macrophage phenotypes (M1) exhibit anti-tumor activity, distinct phenotypes (M2) may contribute to malignant progression and metastasis. In this study, we show that M2 macrophages promote Ewing Sarcoma invasion and extravasation, pointing to a potential target of anti-metastatic therapy. CNI-1493 is a selective inhibitor of macrophage function and has shown to be safe in clinical trials as an anti-inflammatory agent. In a xenograft mouse model of metastatic Ewing Sarcoma, CNI-1493 treatment dramatically reduces metastatic tumor burden. Furthermore, metastases in treated animals have a less invasive morphology. We show in vitro that CNI-1493 decreases M2-stimulated Ewing Sarcoma tumor cell invasion and extravasation, offering a functional mechanism through which CNI-1493 attenuates metastasis. These data indicate that CNI-1493 may be a safe and effective adjuvant agent for the prevention and treatment of metastatic Ewing Sarcoma.

Ewing Sarcoma: Current Management and Future Approaches Through Collaboration

Ewing sarcoma (ES) is an aggressive sarcoma of bone and soft tissue occurring at any age with a peak incidence in adolescents and young adults. The treatment of ES relies on a multidisciplinary approach, coupling risk-adapted intensive neoadjuvant and adjuvant chemotherapies with surgery and/or radiotherapy for control of the primary site and possible metastatic disease. The optimization of ES multimodality therapeutic strategies has resulted from the efforts of several national and international groups in Europe and North America and from cooperation between pediatric and medical oncologists. Successive first-line trials addressed the efficacy of various cyclic combinations of drugs incorporating doxorubicin, vincristine, cyclophosphamide, ifosfamide, etoposide, and dactinomycin and identified prognostic factors now used to tailor therapies. The role of high-dose chemotherapy is still debated. Current 5-year overall survival for patients with localized disease is 65% to 75%. Patients with metastases have a 5-year overall survival < 30%, except for those with isolated pulmonary metastasis (approximately 50%). Patients with recurrence have a dismal prognosis. The many insights into the biology of the EWS-FLI1 protein in the initiation and progression of ES remain to be translated into novel therapeutic strategies. Current options and future approaches will be discussed.

Cellular immunotherapy strategies for Ewing sarcoma

Ewing sarcoma is a rare cancer of bone and soft tissues defined by a specific chromosomal rearrangement. Preclinical development of immunological treatment strategies includes expansion of T cells with native or grafted T-cell receptor specificities for Ewing sarcoma-associated intracellular antigens, and T-cell engineering with chimeric antigen receptors targeting surface antigens. In vitro preactivated NK cells may also have activity in this cancer. Major challenges are the heterogeneity of antigen expression in individual Ewing sarcomas, and the coexpression of most candidate targets on normal cells. Moreover, homing of therapeutic effector cells to both primary and metastatic tumor sites and adequate function within the immunosuppressive tumor microenvironment will have to be ensured to allow for effective immune targeting of this cancer.

Bone- and cartilage-forming tumors and ewing sarcoma: an update with a gnathic emphasis

Over the past decade, there have been remarkable advances in bone tumor pathology. Insights into the genetic basis and pathobiology of many tumor types have impacted diagnosis, classification, and treatment. However, because gnathic lesions may comprise only a small proportion of cases overall for many tumors, clinicopathologic features and management considerations specific to this subset may be overlooked. Here we provide a summary of recent developments in the following tumor types: osteosarcoma (OS), chondrosarcoma (CS), osteoid osteoma (OO), osteoblastoma (OB), and Ewing sarcoma (ES). In particular, we will give special consideration to cases arising in the jaws.

Gene expression profiling of peripheral blood cells: new insights into Ewing sarcoma biology and clinical applications

Ewing sarcoma (ES) is a group of highly aggressive small round cell tumors of bone or soft tissue with high metastatic potential and low cure rate. ES tumors are associated with a rapid osteolysis and necrosis. The currently accepted clinical prognostic parameters do not accurately predict survival of high-risk patients. Moreover, neither the subtype of EWS-FLI1/ERG in the tumor, nor the detection of fusion transcripts in the peripheral blood (PB) samples, has prognostic value in ES patients. We evaluated the prevalence of circulating tumor cells (CTCs) in 34 adult ES patients. Since CTCs were confirmed in only small subset of patients, we further explored the expression profiles of PB leukocytes using a panel of genes associated with immune system status and increased tumor invasiveness. Moreover, we analyzed the alterations of the routine blood tests in the examined cohort of patients and correlated our findings with the clinical outcome. A uniform decrease in ZAP70 expression in PB cells among all ES patients, as compared to healthy individuals, was observed. Monocytosis and the abnormal expression of CDH2 and CDT2 genes in the PB cells significantly correlated with poor prognosis in ES patients. Our study supports the previously proposed hypothesis of systemic nature of ES. Based on the PB cell expression profiles, we propose a mechanism by which immune system may be involved in intensification of osteoclastogenesis and disease progression in ES patients. Moreover, we demonstrate the prognostic value of molecular PB testing at the time of routine histopathological diagnosis.

[Chemotherapeutic concepts for bone sarcomas]

BACKGROUND

Osteosarcoma and Ewing sarcoma are the most common chemosensitive sarcomas of the bone.

AIM

Development in chemotherapeutic concepts as well as current and future treatment strategies in osteosarcoma and Ewing sarcoma are presented.

METHODS

A PubMed search for "Osteosarcoma" and "Ewing sarcoma" was performed, and pertinent results were summarized.

RESULTS

In both osteosarcoma and Ewing sarcoma, outcomes achieved with multimodal treatment concepts combining conventional chemotherapy and local treatment have reached a plateau of about 70% for 5-year survival rates.

DISCUSSION

Improved insights into the molecular biology and genetics of the diseases as well as insights into the interactions between sarcoma cells and the micro-environment and the immune system are necessary to identify novel therapeutic targets in bone sarcomas. Because of the rarity of the diseases, multinational cooperation is essential to evaluate novel therapies in prospective randomized trials.

In vitro antitumor effect of sodium butyrate and zoledronic acid combined with traditional chemotherapeutic drugs: a paradigm of synergistic molecular targeting in the treatment of Ewing sarcoma

Histone deacetylase inhibitors and bisphosphonates have a promising future in the treatment of cancer as targeted anticancer drugs, particularly when used together or in combination with other cytotoxic agents. However, the effects of these combined treatments have not yet been systematically evaluated in Ewing sarcoma. The in vitro effects on cellular proliferation, viability and survival were investigated in two Ewing sarcoma cell lines, SK-ES-1 and RD-ES. The cell lines were treated with sodium butyrate, a histone deacetylase inhibitor and zoledronic acid, a bisphosphonate, alone, together or in combination with chemotherapeutic drugs recommended for clinical treatment of Ewing sarcoma. The data demonstrated that the combination of sodium butyrate and zoledronic acid had a synergistic cytotoxic effect at 72 h following treatment, persisting for 10-14 days post-treatment, in both cell lines tested. All combinations between sodium butyrate or zoledronic acid and the traditional antineoplastic drugs (doxorubicin, etoposide and vincristine) demonstrated a synergistic cytotoxic effect at 72 h in SK-ES-1 and RD-ES cells, except for the combinations of sodium butyrate with vincristine and of zoledronic acid with doxorubicin, which showed only an additive effect in RD-ES cell lines as compared to each agent alone. These acute effects observed in both Ewing sarcoma cell lines were confirmed by the clonogenic assay. The present data suggest that combining histone deacetylase inhibitors and bisphosphonates with traditional chemotherapeutic drugs is a promising therapeutic strategy for the treatment of Ewing sarcoma, and provides a basis for further studies in this field.

The role of SIOP as a platform for communication in the global response to childhood cancer

Since the year 2000, there has been a 35% annual decrease in mortality among children under the age of five worldwide. The decrease is mainly attributed to the decrease in childhood epidemic infections, for example, due to vaccination programs. In the near future, this decrease will draw attention to paediatric non-communicable diseases (NCDs), and cancer is one of the most common. Access to care for children with cancer and survival rates have improved dramatically in high-income countries. However, it is important that a global perspective addresses problems in developing countries in particular. To meet this challenge, it is critical that emphasis is placed on demands such as access to care and drugs that are known to be effective, and which can be safely administered in resource-limited settings. Additionally, cancer registries and improved health care structures that include care for children with cancer, are paramount for further progress to increase awareness and the survival of children with cancer. The purpose of this paper is to describe current worldwide interventions to improve childhood cancer from the perspective of the International Society of Paediatric Oncology (SIOP). This global perspective will serve as an introduction to a series of papers from six SIOP continental branches, which will highlight the specific and/or common issues related to children with cancer worldwide. To strengthen the communication among and synergistic effects of various paediatric cancer stakeholders, SIOP could serve as a global platform for a proposed Global Paediatric Cancer Network through the interaction of its continental branches and partner collaborations.

Optimal management of Ewing sarcoma family of tumors: recent developments in systemic therapy

The Ewing sarcoma family of tumors (ESFT) is defined by cell surface expression of CD99 and a translocation involving EWS and an ETS partner. Cytotoxic chemotherapy remains the benchmark of first- and second-line therapy, and although the majority of patients with localized disease are cured, almost one third of patients relapse or progress from their disease. Moreover, cure remains elusive in most patients who present with distant metastases. In recent years, the ESFT literature has been dominated by reports of attempts at modulating the insulin-like growth factor (IGF) receptor (IGFR). Unfortunately, three phase II studies examining inhibiting antibodies to IGFR-1 published disappointing results. Whether these results were due to failure to modulate the pathway or other limitations in study design and/or patient selection remain unclear. Other novel strategies currently being investigated in ESFT include tyrosine kinase, mammalian target of rapamycin (mTOR), and poly(ADP-ribose) polymerase (PARP) inhibitors.

Molecular mechanisms of ETS transcription factor-mediated tumorigenesis

The E26 transformation-specific (ETS) family of transcription factors is critical for development, differentiation, proliferation and also has a role in apoptosis and tissue remodeling. Changes in expression of ETS proteins therefore have a significant impact on normal physiology of the cell. Transcriptional consequences of ETS protein deregulation by overexpression, gene fusion, and modulation by RAS/MAPK signaling are linked to alterations in normal cell functions, and lead to unlimited increased proliferation, sustained angiogenesis, invasion and metastasis. Existing data show that ETS proteins control pathways in epithelial cells as well as stromal compartments, and the crosstalk between the two is essential for normal development and cancer. In this review, we have focused on ETS factors with a known contribution in cancer development. Instead of focusing on a prototype, we address cancer associated ETS proteins and have highlighted the diverse mechanisms by which they affect carcinogenesis. Finally, we discuss strategies for ETS factor targeting as a potential means for cancer therapeutics.

Biomarkers in Ewing Sarcoma: The Promise and Challenge of Personalized Medicine. A Report from the Children's Oncology Group

A goal of the COG Ewing Sarcoma (ES) Biology Committee is enabling identification of reliable biomarkers that can predict treatment response and outcome through the use of prospectively collected tissues and correlative studies in concert with COG therapeutic studies. In this report, we aim to provide a concise review of the most well-characterized prognostic biomarkers in ES, and to provide recommendations concerning design and implementation of future biomarker studies. Of particular interest and potentially high clinical relevance are studies of cell-cycle proteins, sub-clinical disease, and copy number alterations. We discuss findings of particular interest from recent biomarker studies and examine factors important to the success of identifying and validating clinically relevant biomarkers in ES. A number of promising biomarkers have demonstrated prognostic significance in numerous retrospective studies and now need to be validated prospectively in larger cohorts of equivalently treated patients. The eventual goal of refining the discovery and use of clinically relevant biomarkers is the development of patient specific ES therapeutic modalities.