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This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Highlights d Undifferentiated sarcomas contain biologically relevant molecular subgroups d Identification of mismatch repair deficiency open up alternate avenues for therapy d Pseudohaploidization is a recurrent event in undifferentiated sarcomas d Copy-number signatures are useful for inferring states of sarcoma evolution

Metastatic spread is the single-most powerful predictor of poor outcome in Ewing sarcoma (ES). Therefore targeting pathways that drive metastasis has tremendous potential to reduce the burden of disease in ES. We previously showed that activation of the ERBB4 tyrosine kinase suppresses anoikis, or detachment-induced cell death, and induces chemoresistance in ES cell lines in vitro. We now show that ERBB4 is transcriptionally overexpressed in ES cell lines derived from chemoresistant or metastatic ES tumours. ERBB4 activates the PI3K-Akt cascade and focal adhesion kinase (FAK), and both pathways contribute to ERBB4-mediated activation of the Rac1 GTPase in vitro and in vivo. ERBB4 augments tumour invasion and metastasis in vivo, and these effects are blocked by ERBB4 knockdown. ERBB4 expression correlates significantly with reduced disease-free survival, and increased expression is observed in metastatic compared to primary patient-matched ES biopsies. Our findings identify a novel ERBB4-PI3K-Akt-FAK-Rac1 pathway associated with aggressive disease in ES. These results predict that therapeutic targeting of ERBB4, alone or in combination with cytotoxic agents, may suppress the metastatic phenotype in ES.

Epithelioid hemangioendothelioma (EHE) is an ultra-rare, translocated, vascular sarcoma. EHE clinical behavior is variable, ranging from that of a low-grade malignancy to that of a high-grade sarcoma and it is marked by a high propensity for systemic involvement. No active systemic agents are currently approved specifically for EHE, which is typically refractory to the antitumor drugs used in sarcomas. The degree of uncertainty in selecting the most appropriate therapy for EHE patients and the lack of guidelines on the clinical management of the disease make the adoption of new treatments inconsistent across the world, resulting in suboptimal outcomes for many EHE patients. To address the shortcoming, a global consensus meeting was organized in December 2020 under the umbrella of the European Society for Medical Oncology (ESMO) involving >80 experts from several disciplines from Europe, North America and Asia, together with a patient representative from the EHE Group, a global, disease-specific patient advocacy group, and Sarcoma Patient EuroNet (SPAEN). The meeting was aimed at defining, by consensus, evidence-based best practices for the optimal approach to primary and metastatic EHE. The consensus achieved during that meeting is the subject of the present publication.

No abstract

11502 Background: Five-year survival of RR-ES is about 15%. Several chemotherapy regimens are used, but without robust evidence. rEECur, the first randomised controlled trial in this setting, is defining a standard of care, balancing efficacy and toxicity. Methods: Patients aged 4 to 50 with RR-ES and fit to receive chemotherapy were randomised between topotecan & cyclophosphamide (TC), irinotecan & temolozomide (IT), gemcitabine & docetaxel (GD) or high-dose ifosfamide (IFOS). Primary outcome measure was objective response (OR) after 4 cycles by RECIST 1.1. Secondary outcomes included PFS, OS and toxicity. A probability-based Bayesian approach was used with multiple pairwise comparisons. At the first interim analysis patients allocated to GD had worse OR and PFS than the other arms and accrual to the GD arm was halted. The second interim assessment was planned to determine which arm should be closed when at least 75 evaluable patients had been recruited to the remaining arms and evaluated for the primary outcome measure. Results: 366 patients (87% RECIST-evaluable), recruited between 18/12/14 and 17/12/19, were randomised to TC (n=124), IT (118), GD (72) and IFOS (53). Median age was 20 years (range 4-49). Patients had: refractory disease (19%), first recurrence (66%), > first recurrence (14%). Initial disease site was bone in (66%). Sites of progression were: primary site only (16%) pleuropulmonary only (32%), other metastatic (52%). At median follow up of 9.2 months, outcome in the IT arm was: response rate 20%, median PFS 4.7 months (95% CI: 3.4 to 5.7), median OS 13.9 months (95% CI: 10.6 to 18.1). The table shows, for each pairwise comparison of IT with the other open arms (randomly labelled A and B to maintain blinding), the probabilities that OR, PFS and OS were better for X than for each other arm (RR = risk ratio, HR = hazard ratio). For OR, PFS and OS, all comparisons favoured arms A and B. The main grade 3/4 adverse events (% patients with an event) for IT (left hand values) compared with A and B pooled were: vomiting (6% v 1%), nausea (6% v 0%), diarrhoea (17% v 0%), fatigue (3% v 1%) and febrile neutropenia (3% v 24%). Conclusions: The first randomised trial in RR-ES has shown that IT, used as a control arm in planned and ongoing randomised phase II studies in RR-ES, is less effective than A and B in achieving tumour shrinkage or prolonging PFS and OS. The remaining two arms are continuing to recruit patients. Clinical trial information: ISRCTN36453794 . [Table: see text]