Intensity Harmonization Techniques Influence Radiomics Features and Radiomics-based Predictions in Sarcoma Patients

International audienceIntensity harmonization techniques (IHT) are mandatory to homogenize multicentric MRIs before any quantitative analysis because signal intensities (SI) do not have standardized units. Radiomics combine quantification of tumors' radiological phenotype with machine-learning to improve predictive models, such as metastasticrelapse-free survival (MFS) for sarcoma patients. We post-processed the initial T2weighted-imaging of 70 sarcoma patients by using 5 IHTs and extracting 45 radiomics features (RFs), namely: classical standardization (IHTstd), standardization per adipose tissue SIs (IHTfat), histogram-matching with a patient histogra

BAF complex deregulation in epithelioid sarcomas and their genetic variants

Les sarcomes épithélioides sont caractérisés dans 85% des cas par une perte d'expression nucléaire de la protéine SMARCB1, codée par un gène suppresseur de tumeurs situés en 22q11 impliqué dans la génèse des tumeurs rhabdoides malignes. L'exploration par BAC-FISH (Bacterial Artificial Chromosome- Fluorescence In Situ Hybridization) d'une série de 40 sarcomes épithélioides a permis d'établir que cette perte d'expression était secondaire dans 85% des cas à des délétions homozygotes et a mis en évidence le premier cas de sarcome épithélioide associé à une délétion germinale de SMARCB1, altération jusqu'alors uniquement identifiée dans les tumeurs rhabdoides malignes. Nous avons par la suite testé le gène suppresseur de tumeurs SMARCA4 comme gène candidat impliqué dans les sarcomes épithélioides SMARCB1-conservés à partir d'une série rétrospective de 16 cas. SMARCA4 code la sous-unité ATPase du complexe BAF dont SMARCB1 représente une sous unité. Ce screening initial a permis d'identifier 6 cas de sarcomes SMARCA4-inactivés dont la localisation était exclusivement thoracique et dont les caractéristiques clinique et anatomopathologique stéréotypées ont permis le recrutement prospectif et rétrospectif de nouveaux cas. L'étude par RNA-sequencing d'une fraction de notre cohorte (n=13/19) a confirmé leur homogénéité transcriptomique et souligné leur parenté avec les tumeurs rhabdoides SMARCB1 et SMARCA4 déficientes. L'absence de mutation germinale fréquente (n=1/11) a fait proposer le terme de sarcome thoracique SMARCA4-déficient (SMARCA4-DTS) en proscrivant l'utilisation du qualificatif « rhabdoide ». La parenté transcriptomique de ces tumeurs laisse entrevoir des vulnérabilités thérapeutiques communes qui restent à identifierEpithelioid sarcomas (ES) display loss of SMARCB1 nuclear expression in 85% of cases. SMARCB1 is encoded by a tumor suppressor gene located in 22q11 which was first linked to cancer in malignant rhabdoid tumors. While investigating a series of 40 epithelioid sarcomas with BAC-FISH (Bacterial Artificial Chromosome-Fluorescence In Situ Hybridization), we demonstrated that SMARCB1 loss in ES occurred through genomic deletions in 85% of cases. We were also able to highlight the first case of ES associated with a heterozygous SMARCB1 deletion in the germ line, which feature was previously thought to be restricted to malignant rhadboid tumors (MRT). We subsequently investigated a series of 16 SMARCB1-retained ES to identify its underlying culprit gene with a focus on the candidate tumor suppressor gene SMARCA4. SMARCA4 encodes one of the ATPase subunit of BAF complexes. Interestingly, SMARCB1 is also a core submit of these complexes which regulate chromatin remodeling. We were able to identify a set of 6 cases displaying SMARCA4 inactivation with this discovery cohort. The review of medical records highlighted these cases had similar presentation : all tumors presented with large compressive and aggressive mediastinopulmonary masses. We further recruited 13 cases based on these characteristics including 5 prospective cases. The characterization of their transcriptomes by RNA-sequencing (n=13/19) confirmed their remarkable homogeneity, all our samples clustering together with MRT. However our variant diverge from malignant rhabdoid tumors as it lacks SMARCA4 alteration in the germline (n=0/11) and displays complex polyploidy genetic profiles. We therefore called this new tumor variant “SMARCA4-deficient thoracic sarcoma” (SMARCA4-DTS). The transcriptomic vicinity of SMARCA4-DTS and MRT let foresee they share common therapeutic vulnerabilitie

Etude in vitro de la voie de signalisation mTOR dans les sarcomes à génomique complexe

Les sarcomes sont des tumeurs malignes mésenchymateuses hétérogènes. Leur caractérisation biologique a permis d'identifier des groupes distincts sur le plan moléculaire parmi lesquels les "sarcomes à génomique complexe" réprésente environ 40%. Ces sarcomes présentent des profils génomiques très réarrangés témoignant d'une forte instabilité génomique. Ils affectent principalement les adultes, leur pronostic est réservé aux stades avancés et métastatiques. L'étude de grandes séries a souligné la fréquence d'altérations génomiques comme les délétions en I Oq comportant le locus du gène suppresseur de tumeur PTEN. Les modèles murins Pten déficients développent des carcinomes et des sarcomes dont la croissance est stimulée via l'axe de signalisation P13K AKT-mTOR. Les inhibiteurs de mTOR stoppent la croissance tumorale des tumeurs murines et certaines lignées cellulaires humaines Pten déficientes. Nous avons étudié le potentiel thérapeutique de cet axe de signalisation dans les sarcomes à génomique complexe en sélectionnant des lignées de sarcome dérivant de tumeurs humaines présentant ou non une délétion hétérozygote de PTEN. Nous avons évalué le niveau d'activation du pathway par western blot sans et sous traitement et mesuré les effets antiprolifératif et proapoptotique d'inhibiteurs de mTOR (Rapamycine, RAD001, PP242) et d'anticorps monoclonaux anti-IGF-1 R (R1507, R7072). Les lignées de sarcome étudiées présentent des niveaux d'activité hétérogène de la voie mTOR en western blot. Les protéines P-p70S6K et P-S6RP sont fortement exprimées dans les lignées PTEN délétées. Les rapalogues (rapamycine, RADOOI) n'induisent qu'un effet antiprolifératif modeste, de type cytostatique. Le TORKinib testé (PP242) induit un effet antiprolifératif marqué conjointement associé à une induction apoptotique. La forte activité du PP242 pourrait s'expliquer par l'inhibition spécifique du complexe TOR2 et de l'inhibition complète de TORC1. Toutefois les lignées PTEN délétées ne sont pas sensibilisées à l'action des inhibiteurs de mTOR. Ces résultats concordent avec des données expérimentales récentes démontrant les limites du concept d' addiction oncogénique . Une même altération génomique contribue différemment à la tumorigénèse en fonction du stade de l'oncogénèse et des altérations génomiques associées. Ces résultats soulignent l'importance des études pré cliniques développant une approche génomique fonctionnelle et visant à caractériser les conséquences d'altérations génomiques concomittantes sur le phénotype tumoral, pour pouvoir in fine identifier des biomarqueurs prédictifs de réponse à une thérapie ciblée.ROUEN-BU Médecine-Pharmacie (765402102) / SudocSudocFranceF

Hémangioendothéliome épithélioïde

International audienc

ATR Inhibition Broadly Sensitizes Soft-Tissue Sarcoma Cells to Chemotherapy Independent of Alternative Lengthening Telomere (ALT) Status

International audienceOnly few drugs have shown activity in patients with advanced soft-tissue and the median overall survival is only 18 months. Alterations of genes involved in the DNA damage repair pathway have been associated with sarcoma risk and prognosis. ATR plays a crucial role in maintaining genomic integrity by responding to a large spectrum of DNA damage, including double strand breaks (DSBs) that interfere with replication. The objective of this study is to evaluate the pre-clinical activity of ATR inhibition in soft tissue sarcomas (STS). We explored the ability of the ATR inhibitor, VE-822, to prevent chemotherapy-induced intra-S-phase checkpoint activation and evaluated the antitumor potential of this combination in vitro and in vivo in STS cell lines and in a patient-derived xenograft model. The combination of VE-822 and gemcitabine in vitro was synergistic, inhibited cell proliferation, induced apoptosis, and accumulated in the S phase of the cell cycle with higher efficacy than either single agent alone. The combination also resulted in enhanced γH2AX intranuclear accumulation as a result of DNA damage induction. These effects were unrelated to the alternative lengthening of telomeres pathway. In vivo, the combination of VE-822 and gemcitabine significantly enhanced tumor growth inhibition and progression-free survival in an aggressive model of undifferentiated pleomorphic sarcoma. The combination of ATR inhibitor and chemotherapy is beneficial in pre-clinical models of soft-tissue sarcoma and deserves further exploration in the clinical setting

Activity of trabectedin and the PARP inhibitor rucaparib in soft-tissue sarcomas

Abstract Background Trabectedin has recently been approved in the USA and in Europe for advanced soft-tissue sarcoma patients who have been treated with anthracycline-based chemotherapy without success. The mechanism of action of trabectedin depends on the status of both the nucleotide excision repair (NER) and homologous recombination (HR) DNA repair pathways. Trabectedin results in DNA double-strand breaks. We hypothesized that PARP-1 inhibition is able to perpetuate trabectedin-induced DNA damage. Methods We explored the effects of combining a PARP inhibitor (rucaparib) and trabectedin in a large panel of soft-tissue sarcoma (STS) cell lines and in a mouse model of dedifferentiated liposarcoma. Results The combination of rucaparib and trabectedin in vitro was synergistic, inhibited cell proliferation, induced apoptosis, and accumulated in the G2/M phase of the cell cycle with higher efficacy than either single agent alone. The combination also resulted in enhanced γH2AX intranuclear accumulation as a result of DNA damage induction. In vivo, the combination of trabectedin and rucaparib significantly enhanced progression-free survival with an increased percentage of tumor necrosis. Conclusion The combination of PARP inhibitor and trabectedin is beneficial in pre-clinical models of soft-tissue sarcoma and deserves further exploration in the clinical setting

Identifying and targeting cancer stem cells in leiomyosarcoma: prognostic impact and role to overcome secondary resistance to PI3K/mTOR inhibition

Abstract Background Leiomyosarcoma (LMS) is one of the most frequent soft tissue sarcoma subtypes and is characterized by a consistent deregulation of the PI3K/mTOR pathway. Cancer stem cells (CSCs) have been poorly studied in soft tissue sarcomas. In this study, we aimed to evaluate the association between CSCs, the outcome of LMS patients, and the resistance to PI3K/mTOR pathway inhibition. Methods We investigated the relationships between aldehyde dehydrogenase 1 (ALDH1) expression, a cancer stem cell marker, and the outcome of LMS patients in two independent cohorts. We assessed the impact of CSCs in resistance to PI3K/mTOR pathway inhibition using LMS cell lines, a xenograft mouse model, and human tumor samples. Results We found that enhanced ALDH1 activity is a hallmark of LMS stem cells and is an independent prognostic factor. We also identified that secondary resistance to PI3K/mTOR pathway inhibition was associated with the expansion of LMS CSCs. Interestingly, we found that EZH2 inhibition, a catalytic component of polycomb repressive complex which plays a critical role in stem cell maintenance, restored sensitivity to PI3K/mTOR pathway inhibition. Importantly, we confirmed the clinical relevance of our findings by analyzing tumor samples from patients who showed secondary resistance after treatment with a PI3Kα inhibitor. Conclusions Altogether, our findings suggest that CSCs have a strong impact on the outcome of patients with LMS and that combining PI3K/mTOR and EZH2 inhibitors may represent a promising strategy in this setting

Genetic variant of SRF-rearranged myofibroma with a misleading nuclear expression of STAT6 and STAT6 involvement as 3′ fusion partner

International audiencePediatric neoplasms with a myofibroblastic differentiation are frequent in children, in particular myofibroma. Recently, a novel deep soft tissue myofibroblastic neoplasm has been described with high cellularity, a smooth muscle phenotype and SRF-RELA fusion. We report the case of a 15-year-old boy who presented with a tumor of the deep soft tissue of the arm, with overlapping histological features with the recently described SRF-RELA group of myofibromas but differing by the presence of calcifications, a novel SRF-STAT6 fusion transcript and nuclear expression of STAT6. No local recurrence nor distant metastasis was detected at the current follow-up of 29 months. The clinical relevance of this novel fusion requires further investigations