Translational Surgery

: 2017  |  Volume : 2  |  Issue : 1  |  Page : 14--18

Advances in multi-therapies for the treatment of Ewing's sarcoma

Lei Zhang, Xing Zhou, Xiaozhou Liu, Chengjun Li, Sujia Wu 
 Department of Orthopedics, School of Medicine, Jinling Hospital, Nanjing University, Nanjing, Jiangsu, China

Correspondence Address:
Sujia Wu
Department of Orthopedics, School of Medicine, Jinling Hospital, Nanjing University, Nanjing 210002, Jiangsu


Ewing's sarcoma (ES) is a type of bone and soft tissue tumor that is highly invasive and primarily occurs in children and adolescents. In recent years, with the combination chemotherapy, surgery, and radiotherapy, prognosis, and quality of life have significantly improved. The overall survival (OS) rate is 65%–75%. However, metastasis and recurrence after surgical resection are still the main determinants of mortality. The OS rate in these patients is <30%. Exploring the pathogenesis of ES and looking for effective targeted therapies are the primary focus of many research teams. A global effort to improve the clinical efficacy of chemotherapy while reducing the toxic side effects, has led to further advances. We summarize the current multidisciplinary treatment advances in ES, with an emphasis on molecular targeted therapy and immunotherapy.

How to cite this article:
Zhang L, Zhou X, Liu X, Li C, Wu S. Advances in multi-therapies for the treatment of Ewing's sarcoma.Transl Surg 2017;2:14-18

How to cite this URL:
Zhang L, Zhou X, Liu X, Li C, Wu S. Advances in multi-therapies for the treatment of Ewing's sarcoma. Transl Surg [serial online] 2017 [cited 2020 Feb 29 ];2:14-18
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Full Text


Ewing's sarcoma (ES) is a poorly differentiated small round cell malignant tumor, mainly occurring in children and adolescents. Its incidence is only second to osteosarcoma. Surgical resection combined with chemotherapy and radiation results in a 5-year overall survival (OS) rate was 61%–78%.[1] Recurrence and extrapulmonary metastasis correlate with poor prognosis.[2] The 5-year OS was 23% in patients who relapsed after combined therapy.[3] When compared with patients with systemic multiple metastases, the outcomes of patients with lung-only metastasis was significantly improved, 3-year event-free survival (EFS) and OS were 45.19% and 60.7%, respectively.[4] Currently, chemotherapy drugs for ES include: Vincristine (VCR), cyclophosphamide (CTX), actinomycin D (ACTD), adriamycin (ADR), ifosfamide (IFO), and etoposide (VP-16). Specific chemotherapy regimens largely depend on clinical trials conducted by national and international cooperative organizations. Retrospective studies have detailed improved outcomes for differing stages, highlighting successful chemotherapy strategies. Radiation therapy plays an important role in the treatment for ES as well.

Two decades ago, it was found that a chromosome translocation t (11;22) (q24;q12) commonly occurred in ES. As an abnormal transcription factor, the fusion protein EWS-FLI1 could induce the expression of a variety of target genes thus promoting tumorigenesis.[5] Increasing interest in the immune responses of ES patients has led to the investigation of cell-based immunotherapies and cancer vaccines. Further knowledge gained from multi-center clinical trials and related genetic studies on ES will surely contribute to the design of new biological therapies, provide individualized treatment models, and implement new experimental studies.

 Chemotherapy Plan for Ewing's Sarcoma Patients

Chemotherapy plan for nonmetastatic Ewing's sarcoma patients

Combined neoadjuvant chemotherapy, surgical resection, and radiotherapy have improved the survival rate of ES patients significantly. Factors which affect the prognosis of the nonmetastatic patient include: tumor stage, volume of the tumor, and lesion site.[6] Histologic and radiologic response to chemotherapy are regarded as independent predictors for prognosis and may determine the chemotherapy plan.[7] In 1970, cytotoxic drugs, such as VCR (V), ACTD (A), CTX (D) and ADR (C) were used to improve the life quality of ES. The 5-year recurrence-free survival rate was 60% with chemotherapy. In addition, chemotherapy significantly reduced recurrence and metastatic risks in patients with nonpelvic sites of disease.[8] After 1980, IFO (I) and VP-16 (E) were added in the treatment of ES. Grier et al.[9] indicated the addition of IFO (I) and VP-16 (E) to VDCA, improved 5-year EFS (69% vs. 54%) and OS (72% vs. 61%) significantly compared to the control group. The randomized controlled trial termed European Intergroup Cooperative Sarcoma Study 92 was carried out to compare the efficacy of regimens VAIC versus VADC in standard-risk patients (localized lesion, volume <100 mL). The results showed that the efficacy of IFO and CTX were equivalent. However, the adverse side effects of CTX (leukopenia, thrombocytopenia, mucositis) were higher than IFO.[10] Results of the Euro-EWING99-R1 trial addressed the possibility that CTX might replace IFO in the consolidation stage when treating standard-risk patients (histologic response <10% or volume <200 mL). The long-term assessment of kidney function and gonadal toxicity is ongoing. The results will provide important guidance for clinical treatment strategies.[11] Granulocyte colony-stimulating factor not only allows for an increase in dose of chemotherapy drugs but also shortens the interval of treatment.[12] The study carried out by Children Oncology Group (COG) showed that ES patients who received standard doses of VDC/IE over 48 weeks compared to a dose-intensified regimen of VDC/IE over 30 weeks, did not have an improved 5-year EFS.[13] Subsequent studies carried out by COG confirmed that nonmetastatic patients who received VDC/IE chemotherapy every 2 weeks compared to 3 week intervals, had improved 5-year EFS (73% vs. 65%).[14]

Chemotherapy plan for the Ewing's sarcoma patients with recurrence and metastasis

ES patients who suffer from recurrence and metastasis have a poor prognosis. There is currently no uniform treatment plan. The 5-year survival rate was 24% in patients with local recurrence.[15] Grier et al.[9] suggested that the therapeutic effect in patients with metastasis was not significant with the combination of IE and VDCA. Taking chemotherapy-drug sensitivity and dose-dependency of the ES tumor into account, McTiernan et al.[16] claimed that conventional chemotherapy was synergic with busulfan or melphalan high-dose chemotherapy after autologous bone marrow or peripheral blood stem cell transplantation and that survival rates of patients with recurrence or refractory ES, were improved. They noted an improved 2-year EFS of 42.5% and a 5-year EFS of 38.2%.

The Euro-EWING 99 R3 trial was designed to evaluate multidisciplinary treatment for patients with multiple metastases. Patients received 6-cycle VIDE, 1-cycle VIA, surgery or radiotherapy, and high-dose chemotherapy following autologous stem cell transplantation. The 5-year EFS of children under 14 years old was 46%. Patients' age, volume of the tumor, the type of tumor metastasis (single bone metastasis, bone marrow metastasis, lung metastasis) and other risk factors were used to design the prognostic scoring system.[17] The Italian Sarcoma Group and the Scandinavian Sarcoma Group cooperative study revealed that ES patients with single lung or single bone metastases who received bone marrow transplantation with busulfan or melphalan combined with whole lung irradiation, had a 5-year EFS of 43%.[18] Rasper et al.[19] showed that patients who received high-dose chemotherapy followed by autologous stem cell rescue could decrease the risk of long-term adverse events. The multivariate regression analysis indicated patients who received conventional second-line chemotherapy compared to patients who received high-dose chemotherapy, with a Hazard ratio of 2.90 (95% confidence interval 1.41–6.0).

Retrospective studies and Phase II/III trials conducted by international cooperative organizations are ongoing. Some are evaluating the long-term efficacy and toxicity in patients who have received combination chemotherapy including topotecan, and ACTD, irinotecan, temozolomide, docetaxel, and gemcitabine.

 Radiotherapy for Ewing's Sarcoma

The sensitivity of ES to radiotherapy has led to this modality becoming one of the most important ways to achieve local control and prevent tumor recurrence. Compared with surgery alone, radiation has a higher risk of local failure, independent of the type of the model used for local control, and not related significantly to EFS, OS, or distant failure.[21] An accurate radiotherapy guideline is lacking for both intrinsic patient factors (age, tumor size, location, local control, or metastasis) and external factors (radiotherapy dose, technology, pre- versus post-operative radiation). La et al.[22] proved the efficacy of radiotherapy for local control in ES patients with nonmetastatic disease. Tumor metastasis was considered a very important factor for prognosis, revealing 3-year EFS for nonmetastatic disease compared to metastatic disease as 70% and 21%, respectively. In a retrospective analysis, Schuck et al.[23] analyzed 153 cases of ES patients who received postoperative radiotherapy within 60 days compared to those irradiated after 60 days. Patients who received early postoperative radiotherapy had a higher local control rate, but the difference was not statistically significant (the 5-year LC 98% vs. 92%). When evaluating radiotherapy in adult patients (age ≥18 years old) suffering from ES, Casey et al.[24] pointed out that the prognostic factors and outcomes in adult patients were similar to adolescent outcomes. The 5-year EFS and OS of nonmetastatic patients were 44% and 66%, respectively. Another study by the same author indicated radiotherapy was effective in ES patients with bone metastases, reporting a 3-year EFS of 16%. The radiotherapy dose, fractionation, and technology type did not impact the effects of local control at the irradiated site.[25] In a study on 198 cases of thoracic nonmetastatic ES patients, Bedetti et al.[26] suggested that complete resection was still the best modality for chest ES patients. Radiotherapy was only useful in patients with incomplete resection. Choi et al.[27] pointed out that provided the tumor diameter was ≤8 cm, early-stage patients could be treated with chemotherapy and radiotherapy. Otherwise, a combination of surgery and radiotherapy was necessary. A large study by COG indicated that while radiotherapy alone increased the risk of local recurrence, surgery combined with radiotherapy is a reasonable choice for specific patients at an appropriate time.[21]

 Molecular Studies on Targeted Therapies for Ewing's Sarcoma Patients

Glioma-associated oncogene homolog 1

Glioma-Associated Oncogene Homolog 1 (GLI1) is an important downstream transcription factor of the canonical Hedgehog pathway that directly activates the transcription of cancer genes. Zwerner et al.[28] proposed that NIH3T3 cells expressing EWS/FLI1 give increase to a malignant phenotype with an increased level of GLI1. When GLI1 was knocked out, the number of cells transforming into the malignant phenotype was reduced. This suggests that GLI1 might play an important role in the maintenance of a malignant phenotype induced by EWS/FLI1. Beauchamp et al.[29] confirmed that the expression of the GLI1 gene was directly under the targeted control of EWS/FLI1. EWS/FLI1 increases the expression of the GLI1 protein by inducing the transcription of GLI1 thereby stimulating the proliferation of tumor cells. Inhibiting GLI1 protein expression could reduce the proliferation of ES tumor family (ESFT) cells. In addition, Joo et al.[30] found that ES cells expressed GLI1 at a high level. They also confirmed that EWS/FLI1 could regulate GLI1 expression in ES cells (TC71). Therefore, inhibiting the expression of GLI1 with a targeted drug could be a theoretical basis for the treatment of ES. Antineoplastic arsenic trioxide (ATO) has been found to suppress human cancer cell growth and tumor development in mice by inhibiting GLI1.[31] Some related reports pointed out that ATO combined with the chemotherapy drug (VP-16 and paclitaxel) had a low toxicity profile and may be feasible for the treatment of ES and osteosarcoma.[32]

Forkhead box

Forkhead box (FOX) proteins were confirmed to participate in the regulation of cell cycle, proliferation, differentiation, metabolism, and apoptosis.[33] The FOX sub-types (FOXO) was found to inhibit the cancer gene. Yang et al.[34] found that in ES cells with an increase in EWS/FLI1 protein expression, FOXO1 expression decreased. Thus, they suggested EWS/FLI1 protein might combine with the upstream enhancing factors to inhibit FOXO1 expression. Induction of FOXO1 expression in ES cells (A673 and SKNMC) led to cell differentiation dysfunction and decreased the ability of soft agar colony formation. Niedan et al.[35] found that FOXO1 subcellular localization and transcriptional activity were indirectly regulated by EWS/FLI1. Methylimino selenium acid (MSA) could activate the expression of endogenous FOXO1 in ES cells and induce the apoptosis of tumor cells. In an orthotropic mouse xenotransplantation model of ES, MSA could significantly inhibit tumor growth. MSA has also been confirmed to be associated with chemotherapeutic drugs (VP-16, doxorubicin) for the treatment of ES, suggesting a potential therapeutic use of MSA.[36] Among the four kinds of ES cell lines, Christensen et al.[37] found that EWS/FLI1 could up-regulate the expression level of FOXM1. The knockdown experiments confirmed that the decreasing expression of FOXM1 significantly inhibited the anchorage-independent growth ability of ES cell lines. Thiostrepton could also inhibit the expression of FOXM1. The ES mice transplantation model found that thiostrepton inhibited EWS/FLI1 expression at the level of mRNA and protein.[38] The studies reviewed above suggest the FOX gene family might be used as an effective target point in treating ES.

Immune cell-based immunotherapies

The ESFT specific antigens have been identified as targets for cytotoxic T-lymphocytes (CTL). However, peptides derived from fusion proteins induced weak CTL activity against ES cells. Efforts to improve antigen processing and regulate the interactions between ES and T cells have been a focus of ES-directed immunotherapies. The adoptive transfer of CTL specific for the modified peptide YLNPSVDSV could improve the survival of mice with established ES xenografts. When stimulated with YLNPSVDSV peptide, human peripheral blood mononuclear cells have the potential to induce the CTL-killing.[39] Lipase I (LIPI, membrane-associated phospholipase A1-β) is one of the cancer/testis antigens with high specificity for ESFT. CTL specific for LIPI-derived peptides LDYTDAKFV and NLLKHGASL are shown to lyse HLA-A2 positive ESFT cells in vitro.[40]

Integration of natural killer cell-based combination immunotherapy is proposed as a novel way to treat ES by Ahn et al.[41] When the insulin-like growth factor-1 receptor (IGF-1R)-specific antibody is present, NK cell activation is significantly superior. Jamitzky et al.[42] discovered that IGF-1R inhibition could effectively reduce the ES cell viability without affecting the expression of immune-modulatory and major histocompatibility complex molecules. Another study noted that combination of the histone deacetylase inhibitors and interleukin-15-mediated activation of NK cells could improve the immune recognition of chemotherapy-resistant ES.[43]

Cancer vaccines

The oncolytic virus has the ability to infect and kill tumor cells selectively while sparing normal tissues. A systemic delivery of vesicular stomatitis virus (VSVΔM51) resulted in both tumor-specific killing of resistant ES cells and a significant delay in tumor growth in ES-bearing mice according to one study.[44] The FANG immunotherapy comprises autologous tumor cells transfected with the rhGMCSF transgene and the RNAibi-shRNA furin. The safety profile and immune responses were characterized in patients with advanced or metastatic ES who were treated with FANG autologous immunotherapy. One-year actual survival of 73% for FANG-treated patients compared to 23% in those not treated with FANG were reported. The long-term follow-up results showed a survival benefit without evidence of significant toxicity.[45],[46]

 Other Novel Molecular Studies

Currently, there is no accurate or reliable biological indicator to predict prognosis in ES patients. Research surrounding AXL, a member of the tyrosine kinase family, found that AXL has a role in tumor formation, invasion, and metastasis. Fleuren et al.[47] indicated that patients with low AXL expression survived longer than those with high AXL expression (191 months vs. 69 months, P = 0.026).In vitro experiments showed that the AXL inhibitor BGB324 might inhibit ES cell activity and migratory ability. BGB324 may also improve the sensitivity of ES-4 drug resistant cells to ADR and VCR.

Marino et al.[48] found that nonmetastatic ES patients with high miR-34 expression have significantly higher EFS and OS. Likewise, expression of miR-34 in metastatic patients compared to early-stage tumor patients is low. Multi-factor COX regression analysis showed that low miR-34 expression, incomplete necrosis, and a high level of lactate dehydrogenase were confirmed as independent risk factors that impact patient prognosis. Therefore, miR-34 could be used as a basis for stratification of early stage ES patients.

ES patients are vulnerable to distant metastasis, suggesting that micrometastases are present despite early staging by clinical factors. By using nano-materials and microfluidic techniques, we can measure patient, circulating tumor cells, tumor exosomes, and tumor DNA.[49],[50],[51] By utilizing these methods, we might more promptly ascertain the efficacy of various treatment modalities for these patients.


Neoadjuvant chemotherapy, surgery, and radiotherapy significantly improve the survival rate of nonmetastatic ES patients. However, the prognosis in ES patients who suffer from recurrent or metastatic disease remains poor. Clinical trials, retrospective studies, and planned long-term follow-ups were conceived to optimize the combination of chemotherapy drugs, the drug cycles, the order of drug use, and drug dosing to achieve optimal efficacy and decrease toxic responses. Additional studies confirm that bone marrow transplantation or stem cell transplantation, combined with high-dose chemotherapy, is effective in patients with recurrence and metastasis. Although radiotherapy may increase the possibility of local injury and secondary tumor formation, the adjuvant role of radiation therapy in the systematic treatment for patients is well established. The EWS/FLI1 fusion protein appears essential for ES tumor development. Attempts to influence tumor biology by regulating EWS/FLI1 upstream or downstream target genes expression is underway. Novel targeted drug therapies are under investigation. Immunotherapies for ES include immune cell-based immunotherapies and cancer vaccines. In the future, the combination of chemotherapy, surgery, radiotherapy, targeted therapy, and immunotherapy may become commonplace for ES.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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