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Drug resistance is one of the major factors associated with poor outcome of cancer patients. Treatment of Ewing sarcoma (EwS), an aggressive neoplasm mainly affecting children, adolescents and young adults, is associated with therapy failure and tumor relapse in 30-80% of the cases. Thus, it supports the need to explore the mechanisms modulating drug activity. Here, we describe a novel mechanism of drug sensitivity based on the role of EWS::FLI1 in R-loop metabolism. Our results demonstrate that EWS::FLI1 promotes R-loop formation favoring the interaction between DHX9 and elongating RNA polymerase II. In addition, we discovered that EWS::FLI1 kidnaps DHX9 preventing the resolution of TOP1 poisoning-associated R-loops. Our findings indicate that R-loops accumulation promotes replicative stress, genome instability and cell sensitivity to SN-38. Collectively, these results uncover a novel mechanism behind EwS sensitivity to genotoxic agents, with relevant implications for EwS treatment.

[Background] To assess the cost-effectiveness of using next-generation sequencing (NGS) compared to sequential single-testing (SST) for molecular diagnostic and treatment of patients with advanced non-small cell lung cancer (NSCLC) from a Spanish single-center perspective, the Hospital Universitario Virgen del Rocio (HUVR)., [Research design and methods] A decision-tree model was developed to assess the alterations detection alterations and diagnostic cost in patients with advanced NSCLC, comparing NGS versus SST. Model inputs such as testing, positivity rates, or treatment allocation were obtained from the literature and the clinical practice of HUVR experts through consultation. Several sensitivity analyses were performed to test the robustness of the model., [Results] Using NGS for molecular diagnosis of a 100-patients hypothetical cohort, 30 more alterations could be detected and 3 more patients could be enrolled in clinical-trials than using SST. On the other hand, diagnostic costs were increased up to €20,072 using NGS instead of SST. Using NGS time-to-results would be reduced from 16.7 to 9 days., [Conclusions] The implementation of NGS at HUVR for the diagnostic of patients with advanced NSCLC provides significant clinical benefits compared to SST in terms of alterations detected, treatment with targeted-therapies and clinical-trial enrollment, and could be considered a cost-effective strategy., This work was funded by Roche Farma S.A.

Supplementary Table 1. Primers sequences

Supplementary Figure S4. Trabectedin activity on neural differentiation in EWS.

Ewing Sarcoma (ES) shows several deregulated autocrine loops mediating cell survival and proliferation. Therefore, their blockade is a promising therapeutic approach. We previously reported the in vitro effect of insulin-like growth factor 1 receptor (IGF1R)/KIT pathway blockade on ES cell lines, and we now extend our observations to changes induced by this treatment in interacting proteins/networks. A proteomic analysis revealed that Heat Shock Protein (HSP)90 was differentially expressed between ES cell lines sensitive and resistant to specific IGF1R/KIT inhibitors. We therefore inhibited HSP90 with 17-allylamino-17-demethoxygeldanamycin (17-AAG) and siRNA, and observed that ES cell line growth and survival were reduced, especially in the resistant cell lines. Conversely, HSP90 induced–expression conferred resistance to anti-IGF1R/KIT treatment in the sensitive cell lines. 17-AAG treatment induced HSP90 client protein degradation, including AKT, KIT, or IGF1R, by inhibiting their physical interaction with HSP90. Xenograft models developed with A673 ES cell line confirmed that HSP90 inhibition, alone or combined with IGF1R inhibition, significantly reduced tumor growth and expression of client proteins. Remarkably, using two independent clinical sample sets, we have found that nearly half of IGF1R-positive tumors also show HSP90 overexpression. This delineates a subset of patients that could benefit from combination of anti-HSP90 agents when considering IGF1R-targeting therapies. Importantly, sensitivity to drugs such as ADW/IMA depends not only on the levels of expression and basal activation of IGF1R/KIT, but also, and for the first time reported in ES, on the development of the stress response mechanism. Accordingly, HSP90 expression could be a predictive factor of response to IGF1R-targeting therapies. [Cancer Res 2008;68(15):6260–70]

Supplementary Methods, Table 1, Figures 1-8 from A Pivotal Role for Heat Shock Protein 90 in Ewing Sarcoma Resistance to Anti-Insulin-like Growth Factor 1 Receptor Treatment: In vitro and In vivo Study

Background and objectives: Bone tumours are relatively rare and, as a consequence, treatment in a centre with expertise is required. Current treatment guidelines also recommend review by a specialised pathologist. Here we report on international consensus-based datasets for the pathology reporting of biopsy and resection specimens of bone sarcomas. The datasets were produced under the auspices of the International Collaboration on Cancer Reporting (ICCR), a global alliance of major (inter-)national pathology and cancer organisations. Methods and results: According to the ICCR's process for dataset development, an international expert panel consisting of pathologists, an oncologic orthopaedic surgeon, a medical oncologist, and a radiologist produced a set of core and noncore data items for biopsy and resection specimens based on a critical review and discussion of current evidence. All professionals involved were bone tumour experts affiliated with tertiary referral centres. Commentary was provided for each data item to explain the rationale for selecting it as a core or noncore element, its clinical relevance, and to highlight potential areas of disagreement or lack of evidence, in which case a consensus position was formulated. Following international public consultation, the documents were finalised and ratified, and the datasets, including a synoptic reporting guide, were published on the ICCR website. Conclusion:These first international datasets for bone sarcomas are intended to promote high-quality, standardised pathology reporting. Their widespread adoption will improve the consistency of reporting, facilitate multidisciplinary communication, and enhance comparability of data, all of which will help to improve management of bone sarcoma patients.

Ewing Sarcoma (EWS) is an aggressive bone and soft tissue tumor that mainly affects children, adolescents, and young adults. The standard therapy, including chemotherapy, surgery, and radiotherapy, has substantially improved the survival of EWS patients with localized disease. Unfortunately, this multimodal treatment remains elusive in clinics for those patients with recurrent or metastatic disease who have an unfavorable prognosis. Consistently, there is an urgent need to find new strategies for patients that fail to respond to standard therapies. In this regard, in the last decade, treatments targeting epigenetic dependencies in tumor cells and the immune system have emerged into the clinical scenario. Additionally, recent advances in nanomedicine provide novel delivery drug systems, which may address challenges such as side effects and toxicity. Therefore, therapeutic strategies stemming from epigenetics, immunology, and nanomedicine yield promising alternatives for treating these patients. In this review, we highlight the most relevant EWS preclinical and clinical studies in epigenetics, immunotherapy, and nanotherapy conducted in the last five years., This work was supported by FIS-FEDER PI2000003 to E.d.Á.C.; L.H.-P. is supported by the Consejería de Salud y Familias, Junta de Andalucía (RH-0047-2021).

Nanoparticle albumin-bound paclitaxel (nab-paclitaxel) shows potent preclinical anticancer activity in pediatric solid tumors such as Ewing sarcoma, rhabdomyosarcoma and neuroblastoma, but responses in clinical trials have been modest. In this work, we aimed to discover a rational biomarker-based approach to select the right candidate patients for this treatment. We assessed the efficacy of nab-paclitaxel in 27 patient-derived xenografts (PDX), including 14 Ewing sarcomas, five rhabdomyosarcomas and several other pediatric solid tumors. Response rate (partial or complete response) was remarkable in rhabdomyosarcomas (four of five) and Ewing sarcomas (four of 14). We addressed several predictive factors of response to nab-paclitaxel such as the expression of the secreted protein acidic and rich in cysteine (SPARC), chromosomal stability of cancer cells and expression of antiapoptotic members of the B-cell lymphoma-2 (Bcl-2) family of proteins such as Bcl-2, Bcl-xL, Bcl-W and Mcl-1. Protein (immunoblotting) and gene expression of SPARC correlated positively, while immunoblotting and immunohistochemistry expression of Bcl-2 correlated negatively with the efficacy of nab-paclitaxel in Ewing sarcoma PDX. The negative correlation of Bcl-2 immunoblotting signal and activity was especially robust (r = 0.8352; P = 0.0007; Pearson correlation). Consequently, we evaluated pharmacological strategies to inhibit Bcl-2 during nab-paclitaxel treatment. We observed that the Bcl-2 inhibitor venetoclax improved the activity of nab-paclitaxel in highly resistant Bcl-2-expressing Ewing sarcoma PDX. Overall, our results suggest that low Bcl-2 expression could be used to select patients with Ewing sarcoma sensitive to nab-paclitaxel, and Bcl-2 inhibitors could improve the activity of this drug in Bcl-2-expressing Ewing sarcoma.

Nuestra hipótesis es que el aprendizaje de los alumnos mejorará si: i) se in- tegran mejor los contenidos procedimentales con los conceptuales a lo largo de Ciclos de Mejora en Aula (CIMA) que rompan la dicotomía tradicional entre clases teóricas y seminarios/prácticas, y si, además, ii) los alumnos desarrollan un papel activo en el aprendizaje de los contenidos estructurantes, mediante la realización de actividades en el aula, basadas en actividades que el estudiante ha trabajado de forma no presencial. Para llevar a cabo este proyecto hemos empleado la me- todología de CIMA, realizada en el Programa de Formación e Innovación Docente del Profesorado (FIDOP), pero la hemos combinado con el modelo de clase/aula inversa. La evaluación de la actividad, según la técnica de escaleras de aprendi- zaje y evaluación, opiniones de los alumnos, y autoevaluación, plantea algunos posibles puntos de mejora, pero sugiere que la intervención ha sido acertada en líneas generales. Palabras clave: Medicina, anatomía patológica, docencia universitaria, desa- rrollo profesional docente, Clase inversa.

Undifferentiated small round cell sarcomas (SRCSs) of bone and soft tissue comprise a heterogeneous group of highly aggressive tumours associated with a poor prognosis, especially in metastatic disease. SRCS entities mainly occur in the third decade of life and can exhibit striking disparities regarding preferentially affected sex and tumour localization. SRCSs comprise new entities defined by specific genetic abnormalities, namely EWSR1-non-ETS fusions, CIC-rearrangements or BCOR genetic alterations, as well as EWSR1-ETS fusions in the prototypic SRCS Ewing sarcoma. These gene fusions mainly encode aberrant oncogenic transcription factors that massively rewire the transcriptome and epigenome of the as yet unknown cell or cells of origin. Additional mutations or copy number variants are rare at diagnosis and, depending on the tumour entity, may involve TP53, CDKN2A and others. Histologically, these lesions consist of small round cells expressing variable levels of CD99 and specific marker proteins, including cyclin B3, ETV4, WT1, NKX3-1 and aggrecan, depending on the entity. Besides locoregional treatment that should follow standard protocols for sarcoma management, (neo)adjuvant treatment is as yet ill-defined but generally follows that of Ewing sarcoma and is associated with adverse effects that might compromise quality of life. Emerging studies on the molecular mechanisms of SRCSs and the development of genetically engineered animal models hold promise for improvements in early detection, disease monitoring, treatment-related toxicity, overall survival and quality of life., T.G.P.G. was supported by the Matthias-Lackas Foundation, the Dr. Leopold and Carmen Ellinger Foundation, the German Cancer Aid (DKH-70114278 and DKH-70114111), the Gert und Susanna Mayer Foundation, the Boehringer-Ingelheim Foundation, the Federal Ministry of Education and Research (BMBF: SMART-CARE; HEROES-AYA), the Deutsche Forschungsgemeinschaft (DFG-458891500), the SMARCB1 association, and the Barbara und Wilfried Mohr Foundation. F.C.-A. was supported by grants from the Barbara & Hubertus Trettner Foundation, and the Dr. Rolf M. Schwiete Foundation, and the German Cancer Aid.