Tandem high-dose chemotherapy strategy as first-line treatment of primary disseminated multifocal Ewing sarcomas in children, adolescents and young adults

High-dose chemotherapy for Ewing sarcoma and Rhabdomyosarcoma: A systematic review by the Australia and New Zealand sarcoma association clinical practice guidelines working party

INTRODUCTION

Patients with high-risk or metastatic Ewing sarcoma (ES) and rhabdomyosarcoma (RMS) have a guarded prognosis. High-dose chemotherapy (HDT) with autologous stem cell transplant (ASCT) has been evaluated as a treatment option to improve outcomes. However, survival benefits remain unclear, and treatment is associated with severe toxicities.

METHODS

A systematic review was conducted, using the population, intervention, comparison outcome (PICO) model, to evaluate whether utilization of HDT/ASCT impacts the outcome of patients with ES and RMS compared to standard chemotherapy alone, as part of first line treatment or in the relapse setting. Medline, Embase and Cochrane Central were queried for publications from 1990 to October 2022 that evaluated event-free survival (EFS), overall survival (OS), and toxicities. Each study was screened by two independent reviewers for suitability. A qualitative synthesis of the results was performed.

RESULTS

Of 1,172 unique studies screened, 41 studies were eligible for inclusion with 29 studies considering ES, 10 studies considering RMS and 2 studies considering both. In ES patients with high-risk localised disease who received HDT/ASCT after VIDE chemotherapy, consolidation with melphalan-based HDT/ASCT as first line therapy conveyed an EFS and OS benefit over standard chemotherapy consolidation. Efficacy of HDT/ASCT using a VDC/IE backbone, which is now standard care, has not been established. Survival benefits are not confirmed for ES patients with metastatic disease at initial diagnosis. For relapsed/refractory ES, four retrospective studies report improvement in outcomes with HDT/ASCT with the greatest evidence in patients who demonstrate a treatment response before HDT, and in patients under the age of 14. In RMS, there is no proven survival benefit of HDT/ASCT in primary localised, metastatic or relapsed disease.

CONCLUSION

Prospective randomised trials are required to determine the utility of HDT/ASCT in ES and RMS. Selected patients with relapsed ES could be considered for HDT/ASCT.

Ewing Sarcoma Drug Therapy: Current Standard of Care and Emerging Agents

Ewing sarcoma is a translocation-associated sarcoma mainly impacting adolescents and young adults. The classic translocation (EWSR1::FLI1) leads to a fusion oncoprotein that functions as an aberrant transcription factor. As such, the oncogenic driver of this disease has been difficult to target pharmacologically and, therefore, the systemic therapies used to treat patients with Ewing sarcoma have typically been non-selective cytotoxic chemotherapy agents. The current review highlights recent clinical trials from the last decade that provide the evidence base for contemporary drug therapy for patients with Ewing sarcoma, while also highlighting novel therapies under active clinical investigation in this disease. We review recent trials that have led to the establishment of interval-compressed chemotherapy as an international standard for patients with newly diagnosed localized disease. We further highlight recent trials that have shown a lack of demonstrable benefit from high-dose chemotherapy or IGF-1R inhibition for patients with newly diagnosed metastatic disease. Finally, we provide an overview of chemotherapy regimens and targeted therapies used in the management of patients with recurrent Ewing sarcoma.

Outcomes of Pediatric Patients With Metastatic Ewing Sarcoma Treated With Interval Compression

BACKGROUND

Interval compression (IC), a regimen of alternating vincristine/doxorubicin/cyclophosphamide and ifosfamide/etoposide every 2 weeks, improves survival for localized Ewing sarcoma (ES), with uncertain effect on metastatic disease.

MATERIALS AND METHODS

We reviewed the charts of pediatric patients with metastatic ES treated with IC at our center between January 2013 and March 2020. We calculated event-free survival and overall survival (OS) and used log-rank tests for univariate comparisons.

RESULTS

We identified 34 patients 2.7 to 17.1 years of age (median: 11.6 y). Twenty-six patients (76%) had pulmonary metastases, and 14 (41%) had extrapulmonary metastases. All patients received local control therapy: surgery only (n=7, 21%), radiotherapy only (n=18, 53%), or both (n=9, 26%). The estimated 3-year OS and event-free survival were 62%±9% and 39%±9%, respectively. Patients with pulmonary-only and extrapulmonary metastasis had a 3-year OS of 88%±8% and 27%±13%, respectively ( P =0.0074). Age group (above vs. below 12 y), or primary tumor site did not affect survival, but local control therapy did (surgery only, 83%±15%; combined surgery and radiation, 30%±18%; radiation only, 15%±10%; P =0.048).

CONCLUSION

IC yielded similar outcomes for patients with metastatic ES to other reported regimens. We suggest including this approach to other blocks of therapy.

Short-term and long-term prognostic value of histological response and intensified chemotherapy in osteosarcoma: a retrospective reanalysis of the BO06 trial

OBJECTIVES

Cure rate models accounting for cured and uncured patients, provide additional insights into long and short-term survival. We aim to evaluate the prognostic value of histological response and chemotherapy intensification on the cure fraction and progression-free survival (PFS) for the uncured patients.

DESIGN

Retrospective analysis of a randomised controlled trial, MRC BO06 (EORTC 80931).

SETTING

Population-based study but proposed methodology can be applied to other trial designs.

PARTICIPANTS

A total of 497 patients with resectable highgrade osteosarcoma, of which 118 were excluded because chemotherapy was not started, histological response was not reported, abnormal dose was reported or had disease progression during treatment.

INTERVENTIONS

Two regimens with the same anticipated cumulative dose (doxorubicin 6×75 mg/m²/week; cisplatin 6×100 mg/m²/week) over different time schedules: every 3 weeks in regimen-C and every 2 weeks in regimen-DI.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome is PFS computed from end of treatment because cure, if it occurs, may happen at any time during treatment. A mixture cure model is used to study the effect of histological response and intensified chemotherapy on the cure status and PFS for the uncured patients.

RESULTS

Histological response is a strong prognostic factor for the cure status (OR 3.00, 95% CI 1.75 to 5.17), but it has no clear effect on PFS for the uncured patients (HR 0.78, -95% CI 0.53 to 1.16). The cure fractions are 55% (46%-63%) and 29% (22%-35%), respectively, among patients with good and poor histological response (GR, PR). The intensified regimen was associated with a higher cure fraction among PR (OR 1.90, 95% CI 0.93 to 3.89), with no evidence of effect for GR (OR 0.78, 95% CI 0.38 to 1.59).

CONCLUSIONS

Accounting for cured patients is valuable in distinguishing the covariate effects on cure and PFS. Estimating cure chances based on these prognostic factors is relevant for counselling patients and can have an impact on treatment decisions.

TRIAL REGISTRATION NUMBER

ISRCTN86294690.

Heterogeneous Circulating Tumor Cells in Sarcoma: Implication for Clinical Practice

Simple Summary

The present review is aimed to discuss the relevance of assaying for the presence and isolation of circulating tumor cells (CTCs) in patients with sarcoma. Just a few studies have been performed to detect and enumerate viable CTCs in sarcoma and a majority of them still represent proof-of-concept studies, while more frequently tumor cells have been detected in the circulation by using the PCR-based method. Nevertheless, recent advances in technologies allowed detection of epithelial–mesenchymal transitioned CTCs from patients with mesenchymal malignancies, despite results being mostly preliminary. The possibility to identify CTCs holds a great promise for both applications of liquid biopsy in sarcoma for precision medicine, and for research purposes to pinpoint the mechanism of the metastatic process through the characterization of tumor mesenchymal cells. Coherently, clinical trials in sarcoma have been designed accordingly to detect CTCs, for diagnosis, identification of novel therapeutic targets and resistance mechanisms of systemic therapies, and patient stratification.

Abstract

Bone and soft tissue sarcomas (STSs) represent a group of heterogeneous rare malignant tumors of mesenchymal origin, with a poor prognosis. Due to their low incidence, only a few studies have been reported addressing circulating tumor cells (CTCs) in sarcoma, despite the well-documented relevance for applications of liquid biopsy in precision medicine. In the present review, the most recent data relative to the detection and isolation of viable and intact CTCs in these tumors will be reviewed, and the heterogeneity in CTCs will be discussed. The relevance of epithelial–mesenchymal plasticity and stemness in defining the phenotypic and functional properties of these rare cells in sarcoma will be highlighted. Of note, the existence of dynamic epithelial–mesenchymal transition (EMT)-related processes in sarcoma tumors has only recently been related to their clinical aggressiveness. Also, the presence of epithelial cell adhesion molecule (EpCAM)-positive CTC in sarcoma has been weakly correlated with poor outcome and disease progression, thus proving the existence of both epithelial and mesenchymal CTC in sarcoma. The advancement in technologies for capturing and enumerating all diverse CTCs phenotype originating from these mesenchymal tumors are presented, and results provide a promising basis for clinical application of CTC detection in sarcoma.

Augmented Antitumor Activity for Novel Dual PI3K/BDR4 Inhibitors, SF2523 and SF1126 in Ewing Sarcoma

Ewing sarcoma (ES) is the second most common pediatric bone cancer. Despite recent advances in the treatment, patients with metastatic tumors have dismal prognosis and hence novel therapies are urgently needed to combat this cancer. A recent study has shown that phosphoinositide-3 kinase (PI3K) inhibitors can synergistically increase sensitivity to bromodomain and extraterminal domain inhibitors in ES cells and therefore combined inhibition of PI3K and bromodomain and extraterminal domain bromodomain proteins might provide benefit in this cancer. Herein, we have investigated the efficacy of dual PI3K/BRD4 inhibitors, SF2523 and SF1126, for their antitumor activity in ES cell lines. The effect of SF1126 and SF2523 on cell viability and PI3K signaling was assessed on a panel of human ES cell lines. To evaluate the antitumor activity of SF1126, A673 cells were injected intrafemorally into RAG-2-/- mice and treated with 50 mg/kg SF1126 6 days per week, for 30 days. Both SF1126 and SF2523 decreased cell survival and inhibited phosphorylation of AKT in human ES cell lines. In vivo, SF1126 showed a significant reduction in tumor volume. These results suggest that dual PI3K/BRD4 inhibitor, SF1126, has antitumor activity in ES models.

Prognostic and therapeutic factors influencing the clinical outcome of metastatic Ewing sarcoma family of tumors: A retrospective report from the Japan Ewing Sarcoma Study Group

BACKGROUND

The prognosis of patients with metastatic Ewing sarcoma family of tumors (ESFT) remains poor.

PROCEDURE

We retrospectively analyzed 57 patients diagnosed with metastatic ESFT between 2000 and 2018 to identify prognostic and therapeutic factors affecting the clinical outcome.

RESULTS

The 3-year overall survival (OS) rate of the entire cohort was 46.8% (95% confidence interval [CI], 33.0-59.4%). Treatment-related death was not observed. Multivariate analysis identified stem cell transplantation (SCT), response to first-line chemotherapy, and bone metastasis as independent risk factors for OS. Objective response rate to first-line chemotherapy was 65.1% in the 43 evaluable patients. There was no significant difference in the response to different types of first-line chemotherapy. Among patients with lung metastasis alone, the 3-year OS rate was higher in 13 patients who received local treatment than in four who did not, although the difference was not significant.

CONCLUSIONS

One possible reason for the high OS rates was the absence of treatment-related mortality even in patients receiving SCT, which could be attributed to advances in the management of post-SCT complications. Novel first-line chemotherapy strategies need to be established to improve the disease status prior to SCT in a higher proportion of patients.

Double-conditioning regimen consisting of high-dose thiotepa and melphalan with autologous stem cell rescue for high-risk pediatric solid tumors: A second report

BACKGROUND

Pediatric patients with high-risk, relapsed, or refractory solid tumors have a poor prognosis. We have previously reported a dose-finding experience of high-dose chemotherapy consisting of thiotepa and melphalan ("double-conditioning regimen"). Using doses derived from that study, we have treated patients since 2005. We now report a retrospective review of patients treated by this fixed dose.

PROCEDURE

We reviewed 50 patients (median 4 years; range 0-15 years) with high-risk or relapsed/refractory solid tumors treated by this dose-fixed, double-conditioning regimen from April 2005 to May 2014. Doses were thiotepa 800 mg/m² and melphalan 280 mg/m² for children ≥2 years of age, and 32 mg/kg and 6 mg/kg, respectively, for children <2 years of age. Further, doses were reduced according to creatinine clearance with poor renal function.

RESULTS

Nonhematological toxicity was mainly gastrointestinal-grade 3 mucositis (n = 41) and grade 3-4 diarrhea (n = 10). Neurological, renal, and endothelial cell toxicity and sinusoidal obstruction syndrome were not observed. There were two toxic deaths (interstitial viral pneumonia). This regimen demonstrated antitumor activity against several types of tumors. Although the frequency of gastrointestinal toxicity was high, other severe toxicity was not observed.

CONCLUSIONS

Our double-conditioning regimen was very well tolerated and demonstrated antitumor activity. We are moving forward with multi-institutional trials now.

Method to measure the mismatch between target and achieved received dose intensity of chemotherapy in cancer trials: a retrospective analysis of the MRC BO06 trial in osteosarcoma

OBJECTIVES

In cancer studies, the target received dose intensity (tRDI) for any regimen, the intended dose and time for the regimen, is commonly taken as a proxy for achieved RDI (aRDI), the actual individual dose and time for the regimen. Evaluating tRDI/aRDI mismatches is crucial to assess study results whenever patients are stratified on allocated regimen. The manuscript develops a novel methodology to highlight and evaluate tRDI/aRDI mismatches.

DESIGN

Retrospective analysis of a randomised controlled trial, MRC BO06 (EORTC 80931).

SETTING

Population-based study but proposed methodology can be applied to other trial designs.

PARTICIPANTS

A total of 497 patients with resectable high-grade osteosarcoma, of which 19 were excluded because chemotherapy was not started or the estimated dose was abnormally high (>1.25 × prescribed dose).

INTERVENTIONS

Two regimens with the same anticipated cumulative dose (doxorubicin 6×75 mg/m²/week; cisplatin 6×100 mg/m²/week) over different time schedules: every 3 weeks in regimen-C and every 2 weeks in regimen-DI. PRIMARY AND SECONDARY OUTCOME MEASURES: tRDI distribution was measured across groups of patients derived from k-means clustering of treatment data. K-means creates groups of patients who are aRDI-homogeneous. The main outcome is the proportion of tRDI values in groups of homogeneous aRDI.

RESULTS

For nearly half of the patients, there is a mismatch between tRDI and aRDI; for 21%, aRDI was closer to the tRDI of the other regimen.

CONCLUSIONS

For MRC BO06, tRDI did not predict well aRDI. The manuscript offers an original procedure to highlight the presence of and quantify tRDI/aRDI mismatches. Caution is required to interpret the effect of chemotherapy-regimen intensification on survival outcome at an individual level where such a mismatch is present.The study relevance lies in the use of individual realisation of the intended treatment, which depends on individual delays and/or dose reductions reported throughout the treatment.

TRIAL REGISTRATION NUMBER

ISRCTN86294690.

A novel method to address the association between received dose intensity and survival outcome: benefits of approaching treatment intensification at a more individualised level in a trial of the European Osteosarcoma Intergroup

PURPOSE

There is lack of consensus on the prognostic value of received high dose intensity in osteosarcoma survivorship. Many studies have not shown a clear survival benefit when dose intensity is increased. The aim of this study is to go beyond chemotherapy intensification by arm-wide escalation of intended dose and/or compression of treatment schedule, while conversely addressing the relationship between treatment intensity and survival at the patient level. The study focusses on the difference in outcome results, based on a novel, progressively more individualised approach to dose intensity.

METHODS

A retrospective analysis of data from MRC BO06/EORTC 80931 randomised controlled trial for treatment of osteosarcoma was conducted. Three types of post hoc patient groups are formed using the intended regimen: the individually achieved cumulative dose and time on treatment, and the increase of individual cumulative dose over time. Event-free survival is investigated and compared in these three stratifications.

RESULTS

The strata of intended regimen and achieved treatment yields equivalent results. Received cumulative dose over time produces groups with evident different survivorship characteristics. In particular, it highlights a group of patients with an estimated 3-year event-free survival much larger (more than 10%) than other patient groups. This group mostly contains patients randomised to an intensified regimen. In addition, adverse events reported by that group show the presence of increased preoperative myelotoxicity.

CONCLUSIONS

The manuscript shows the benefits of analyzing studies by using longitudinal data, e.g. recorded per cycle. This has impact on the drafting of future trials by showing why such a level of detail is needed for both treatment and adverse event data. The novel method proposed, based on cumulative dose received over time, shows that longitudinal treatment data might be used to link survival outcome with drug metabolism. This is particularly valuable when pharmacogenetics data for metabolism of cytotoxic agents are not collected.

TRIAL REGISTRATION

ISRCTN86294690.

Pazopanib maintenance therapy after tandem high-dose chemotherapy for disseminated Ewing sarcoma

The dismal prognosis of patients with disseminated Ewing sarcoma necessitates the development of novel treatment strategies. Pazopanib is an oral multi-targeted tyrosine kinase inhibitor that is active against advanced soft tissue sarcoma. However, the clinical activity and feasibility of pazopanib for treating Ewing sarcoma remain poorly understood. Moreover, clinical information on the use of tandem high-dose chemotherapy for Ewing sarcoma is limited. A 14-year-old boy with Ewing sarcoma was transferred to our hospital for treatment. Magnetic resonance imaging, computed tomography scans, and bone scintigraphy revealed multiple lesions in the pubis, ilium, ischium, femur, rib, cranial bone, thoracic vertebrae, sacrum, obturator muscle, adductor magnus muscle, testicular cord, and lungs. Bone scintigraphy after intensive chemotherapies confirmed that multiple abnormal accumulations were still present in the cranial bone and pubis. Subsequently, the patient received tandem high-dose chemotherapy including topotecan, and radiotherapy. Abnormal accumulations have disappeared in bone scintigraphy. Subsequently, pazopanib maintenance therapy was initiated. Despite the presence of innumerable lesions at diagnosis, the patient has been in near-complete remission for the past 1 year with pazopanib administration. This confirms that adding pazopanib maintenance therapy after tandem high-dose chemotherapy is a therapeutic option for cases with disseminated Ewing sarcoma.

Bone marrow involvement identifies a subgroup of advanced Ewing sarcoma patients with fatal outcome irrespective of therapy in contrast to curable patients with multiple bone metastases but unaffected marrow

Purpose

Advanced Ewing sarcomas have poor prognosis. They are defined by early relapse (<24 months after diagnosis) and/or by metastasis to multiple bones or bone marrow (BM). We analyzed risk factors, toxicity and survival in advanced Ewing sarcoma patients treated with the MetaEICESS vs. EICESS92 protocols.

Design

Of 44 patients, 18 patients were enrolled into two subsequent MetaEICESS protocols between 1992 and 2014, and compared to outcomes of 26 advanced Ewing sarcoma patients treated with EICESS 1992 between 1992 and 1996. MetaEICESS 1992 consisted of induction chemotherapy, whole body imaging directed radiotherapy to the primary tumor and metastases, tandem high-dose chemotherapy and autologous rescue. In MetaEICESS 2007 this treatment was complemented by allogeneic stem cell transplantation. EICESS 1992 comprised induction chemotherapy, local therapy to the primary tumor only followed by consolidation chemotherapy.

Results

In MetaEICESS 8/18 patients survived in complete remission vs. 2/26 in EICESS 1992 (p<0.05). Survival did not differ between MetaEICESS 2007 and MetaEICESS 1992. Three MetaEICESS patients died of complications, all in MetaEICESS 1992. After exclusion of patients succumbing to treatment related complications (n=3), 7/10 patients survived without BM involvement, in contrast to 0/5 patients with BM involvement. This was confirmed in a multivariate analysis. There was no correlation between BM involvement and the number of metastases at diagnosis.

Conclusion

The MetaEICESS protocols yield long-term disease-free survival in patients with advanced Ewing sarcoma. Allogeneic stem cell transplantation was not associated with increased death of complications. Bone marrow involvement is a risk factor distinct from multiple bone metastases.

Sinusoidal obstruction syndrome/veno-occlusive disease after high-dose intravenous busulfan/melphalan conditioning therapy in high-risk Ewing Sarcoma

This mono-institutional observational study was conducted to determine incidence, severity, risk factors, and outcome of sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD) in high-risk Ewing sarcoma (ES) patients treated with intravenous busulfan and melphalan (BU-MEL) followed by autologous stem cell transplantation (ASCT). During the past 10 years, 75 consecutive ES patients resulted evaluable for the analysis. After diagnosis of SOS/VOD, defibrotide therapy was started as soon as the medication was available. The variables analyzed as potential risk factors were: gender, patient's age at diagnosis, primary tumor site, disease stage, and prior radiation therapy (RT) given, focusing on RT liver exposure. The median age at diagnosis was 18.8 years. Five patients developed moderate to severe SOS/VOD (cumulative incidence, 6.67%). None of 32 pediatric patients (≤17 years) developed SOS/VOD (p = 0.0674). In univariate analysis, prior RT liver exposure resulted statistically significant (p = 0.0496). There was one death due to severe SOS/VOD. This study reports the largest series of high-risk ES patients treated with intravenous BU-MEL before ASCT. The incidence of SOS/VOD was lower when compared with other studies that used oral busulfan. Any prior RT liver exposure should be avoided. Earlier defibrotide treatment confirms to be effective.

A Retrospective Multicentric Study of Ewing Sarcoma Family of Tumors in Patients Older Than 50: Management and Outcome

Ewing's sarcoma family of tumors (EFTs) is a group of rare and aggressive tumors. Data on EFTs in patients (pts) ≥ 50 years are limited and these pts are often not eligible for clinical trials. Some, but not all, studies have reported inferior outcome for older pts with EFTs. We conducted an IRB-approved retrospective analysis among centers of the French Sarcoma Group on pts diagnosed with EFTs at age ≥50 between 2000 and 2012. Clinical features, treatment modality and outcomes were analyzed. Seventy-seven pts were identified, including 36 females (46.8%) and the median age at diagnosis was 56 years (range: 50-86). The primary tumor was located in soft tissue in 59 pts (76.6%). Fifty-six pts (72.7%) had localized disease, among them 49 (87.5%) received chemotherapy in addition to local therapy. Their estimated 3-yr OS and event-free survival (EFS) rates were respectively 73.3% and 62.2%. Recurrence occurred in 43 pts. The estimated 3-yr OS rate was 37% in pts with metastatic disease at presentation. EFTs in pts ≥50 years are more likely to originate from soft tissue and their outcomes appear to be worse than that of younger pts treated with modern protocols.

Size-based detection of sarcoma circulating tumor cells and cell clusters

Metastatic disease is the most important factor in determining the survival of sarcoma patients. Since sarcoma metastasis is predominantly hematogenous, we hypothesized that detection and quantification of circulating tumor cells (CTCs) could reflect response to therapy and risk of metastatic relapse. We evaluated the presence of CTCs using a novel animal model and in the blood of patients with high grade sarcomas utilizing the CellSieve™ size-based low pressure microfiltration system. Sarcoma CTCs were identified based on antibody staining patterns and nuclear morphology. Additionally, RNA was extracted from the CTCs for molecular analysis including demonstration of an EWS-FLI1 translocation, identification of a previously unrecognized p53 mutation in a patient with Ewing sarcoma, and single cell RNA sequencing of CTC from a child with alveolar rhabdomyosarcoma. In mouse xenograft models, the presence of CTC correlates with disease burden and with clinically silent metastases. In human patients, CTCs were readily detected at diagnosis, decreased with successful treatment, and were detectable in the blood of patients with no radiographic evidence of disease prior to the development of overt metastasis. Although evaluation of CTC is established in the care of patients with carcinomas, this technology has yet to be effectively applied to the evaluation and treatment of sarcoma patients. Our work demonstrates that the CellSieve™ microfiltration system can be used to study the biology of CTC in both mouse models and human sarcoma patients, with the potential for application to the monitoring of disease response and prediction of metastatic relapse.

High-Dose Chemotherapy and Autologous Stem Cell Transplantation in Children with High-Risk or Recurrent Bone and Soft Tissue Sarcomas

Despite increasing evidence that high-dose chemotherapy and autologous stem cell transplantation (HDCT/auto-SCT) might improve the survival of patients with high-risk or recurrent solid tumors, therapy effectiveness for bone and soft tissue sarcoma treatment remains unclear. This study retrospectively investigated the feasibility and effectiveness of HDCT/auto-SCT for high-risk or recurrent bone and soft tissue sarcoma. A total of 28 patients (18 high-risk and 10 recurrent) underwent single or tandem HDCT/auto-SCT between October 2004 and September 2014. During follow-up of a median 15.3 months, 18 patients exhibited disease progression and 2 died of treatment-related toxicities (1 veno-occlusive disease and 1 sepsis). Overall, 8 patients remained alive and progression-free. The 3-year overall survival (OS) and event-free survival (EFS) rates for all 28 patients were 28.7% and 26.3%, respectively. In the subgroup analysis, OS and EFS rates were higher in patients with complete or partial remission prior to HDCT/auto-SCT than in those with worse responses (OS, 39.1% vs. 0.0%, P = 0.002; EFS, 36.8% vs. 0.0%, P < 0.001). Therefore, careful selection of patients who can benefit from HDCT/auto-SCT and maximal effort to reduce tumor burden prior to treatment will be important to achieve favorable outcomes in patients with high-risk or recurrent bone and soft tissue sarcomas.

Investigational therapies for Ewing sarcoma: a search without a clear finding

INTRODUCTION

Ewing sarcoma family tumors (ESFT) are a group of aggressive diseases, characterized histologically by small, round, blue cells and genetically by translocation involving EWS and ETS partner genes. The current treatment of localized Ewing sarcoma (ES) requires a multi-disciplinary approach, including multidrug chemotherapy, administrated before and after local treatment, surgery and radiation therapy. Unfortunately, the cure rate of metastatic or refractory/recurrent disease is still very poor.

AREAS COVERED

In this review, the authors summarize the new types of therapy and strategies aimed to improve the prognosis or cure ES. Herein, the authors discuss several preclinical and phase I-II studies with new-targeted therapies. The most studied therapies are insulin-like growth factor receptor (IGF1R) inhibitors but have limited efficacy. Other strategies include Mammalian Target of Rapamycin (mTOR) Inhibition, poly ADP ribose polymerase (PARP) inhibition, vascular endothelial growth factor (VEGF) inhibition, tyrosine kinase inhibitors and telomerase inhibitors, all with limited effectiveness.

EXPERT OPINION

Future treatment strategies should combine one or more targeted therapies with conventional chemotherapy. Some combined modality treatments are under clinical study. However, treatment breakthroughs are still needed to improve the relatively poor prognosis of recurrent/metastatic ESFT.