The early evolutionary landscape of osteosarcoma provides clues for targeted treatment strategies

Osteosarcomas are aggressive primary tumors of bone that are typically detected in locally advanced stages; however, which genetic mutations drive the cancer before its clinical detection remain unknown. To identify these events, we performed longitudinal genome-sequencing analysis of 12 patients with metastatic or refractory osteosarcoma. Phylogenetic and molecular clock analyses were carried out next to identify actionable mutations, and these were validated by integrating data from additional 153 osteosarcomas and pre-existing functional evidence from mouse PDX models. We found that the earliest and thus clinically most promising mutations affect the cell cycle G1 transition, which is guarded by cyclins D3, E1, and cyclin-dependent kinases 2, 4, and 6. Cell cycle G1 alterations originate no more than a year before the primary tumor is clinically detected and occur in >90% and 50% of patients of the discovery and validation cohorts, respectively. In comparison, other cancer driver mutations could be acquired at any evolutionary stage and often do not become pervasive. Consequently, our data support that the repertoire of actionable mutations present in every osteosarcoma cell is largely limited to cell cycle G1 mutations. Since they occur in mutually exclusive combinations favoring either CDK2 or CDK4/6 pathway activation, we propose a new genomically-based algorithm to direct patients to correct clinical trial options

Brown Tumors Belong to the Spectrum of KRAS-driven Neoplasms

Brown tumors are rare and generally self-limiting mass lesions of bone occurring in the context of hyperparathyroidism. Although commonly regarded as endocrine-driven tumor-like lesions, we detected pathogenic hotspot KRAS mutations in 10/16 brown tumors (62%) with similar frequencies found in cases affecting the peripheral and axial skeleton. Pathogenic mutations in other driver genes of the RAS-MAPK pathway were not identified. Our findings suggest brown tumors to represent true neoplasms driven by the activation of the RAS-MAPK signaling pathway. The frequent regression of brown tumors after normalization of hyperparathyroidism points to a second hit mediated by endocrine stimulation to be required for tumor development. Our findings underline the pathogenic relation of brown tumors to nonossifying fibroma and giant cell granuloma of the jaws which both appear histologically similar to brown tumors and are also driven by RAS-MAPK signaling pathway activation

Evaluation of optogene transfer for the treatment of a canine model of inherited retinal dystrophies

La cécité ou la très grande malvoyance peut résulter de différentes pathologies comme les dystrophies rétiniennes héréditaires (DRH) caractérisées par la perte des photorécepteurs. Une des approches pour traiter les DRH est la thérapie génique spécifique, c’est à dire le remplacement du gène défectueux par un gène sain. Des études chez des modèles animaux de DRH ont démontré l’efficacité de la thérapie géniques spécifique, et conduit au lancement d’essais cliniques.Malgré des résultats encourageants, la thérapie génique spécifique n’est pas toujours applicable, en particulier quand la dégénérescence est trop avancée ou si le gène muté est inconnu. Pour traiter tous les cas de DRH, un nouvel axe de thérapie génique est envisagé : le transfert d’optogène.Cette stratégie consiste à réactiver la rétine devenue aveugle par l’expression de protéines photosensibles dans la rétine. Notre objectif est d'évaluer l'efficacité du transfert d'optogène chez un modèle canin naturellement déficient pour le gène Rpe65, provoquant une forme sévère de DRH proche de celles retrouvées chez l’homme. La stratégie thérapeutique retenue est : L'injection intravitréenne, après vitrectomie, d'un vecteur recombinant dérivé du virus adéno-associé de sérotype2 (rAAV2/2), portant le transgène optogénétique sous contrôle d'un promoteur fort et spécifique des tissus neuronaux : hSyn. Le but de ce projet est de transduire efficacement les cellules ganglionnaires rétiniennes d'un modèle canin déficient pour le gène Rpe65 et d'évaluer la photosensibilité des cellules transduites.Inherited retinal diseases (IRD) affect about 2 million people worldwide, leading to severe visual impairment.Specific gene addition therapy is one of the most promising strategies to treat these patients. Howevermany of them are not eligible for specific gene therapy,such as.1) Patients with unknown deficient genes.2) Patients beyond the therapeutic window.3) Patients whose the deficient gene is too large forAAV encapsidation.4) Patients undergoing a dominant form of IRD.Therefore, the aim of this project is to develop analternative strategy, independent of the mutation and the retinal degeneration kinetic: the optogene transfer. In context of IRD, it will consist to convert survivingretinal ganglion cells into sensitive light cells followingthe transfer of ChR2 or Opn4 optogene. Several rodentmodels of IRD have been successfully treated usingthese optogenes. Nevertheless, this approach hasnever been evaluated in large animal models. The objective of our study will be to define the feasibility ofoptogene transfer to restore vision in blind patients by evaluating the safety and the efficacy of AAV-mediated gene transfer of ChR2, eNpHR or Opn4, after vitrectomy, in ganglion cells of a canine model of IRD, the Rpe65-deficient dog

Metastasizing chondroblastoma: a rare bone tumor no longer supported by the WHO classification.

According to the World Health Organization (WHO) classification, tumors showing hematogenous spread in less than 2% of cases are categorized as "rarely metastasizing" and constitute a group of neoplasms of intermediate malignancy. Since its introduction in 2002, chondroblastoma has been considered one of the prototypic examples of this category of lesions. In the fifth and only recently published edition of the WHO classification of bone and soft tissue tumors, however, chondroblastoma was re-classified from rarely metastasizing to benign due to the rarity of cases with systemic spread. Here, we present a remarkable case of a 54-year-old male who presented with an expansile tumor in his left acromion that was diagnosed as chondroblastoma following biopsy. Three years later a local recurrence was noted during routine follow-up and a bone scan detected hypermetabolic lesions in a rib and the thoracic spine. Over time, he developed multifocal skeletal spread as well as soft tissue and pulmonary metastases, which histologically all revealed conventional chondroblastoma morphology and the highly specific H3-3B point mutation (p.Lys36Met). Thirteen years after initial diagnosis he is currently treated with experimental immunotherapy and shows stable but disseminated disease. Our case highlights that although metastasizing chondroblastoma is rare, potential systemic spread should be kept in mind in patients with chondroblastoma despite the new WHO classification

La prise de responsabilité des jeunes et les associations: Courcelles, une pédagogie de l'engagement

National audienceLes acteurs associatifs se plaignent souvent, et de façon récurrente, de l’absence de jeunes ou de militants, sans pour autant, basculer vers une analyse des mécanismes qui permettraient, à des jeunes, de devenir des membres de l’association, engagés et porteurs du projet.Le propos est ici différent. Parler de la prise de responsabilité comme d’un processus, envisager la prise de responsabilité en tant que telle, consiste à passer dans un autre registre, celui d’un processus dans lequel l’individu prend à sa charge et se voit confié, une responsabilité, c’est-à-dire quelque chose qu’il assumera mais aussi quelque chose qu’on choisit de lui confier à la hauteur des capacités qu’on lui prête.En passant par différentes phases, plus ou moins réfléchies avant ce travail, les personnes expérimentent à l’occasion de différentes situations leur capacité à prendre en charge des tâches, des réalisations, face aux autres. Amener les personnes à entrer dans ces situations, à y éprouver la possibilité d’y faire ce qui est attendu, sont différentes modalités permettant que progressivement, avec des niveaux d’implication singuliers, le projet lui-même de l’association se trouve pris en considération.La prise de responsabilité comme processus se révèle être un chemin sur lequel les protagonistes prennent conscience des leviers à prendre en compte pour que le sens du projet de l’association puisse se poursuivre, et donc aussi, des choses qu’il ne faut pas modifier au risque sinon de voir l’ensemble du fonctionnement remis en cause. De nombreuses situations vécues, analysées, discutées, débattues sont nécessaires pour s’approprier les choses mais aussi pour les faire exister. Nous proposons dans cet ouvrage de raconter avec des vignettes et des réflexions théoriques les différentes étapes identifiées, leur contenu, les formes d’accompagnement mises en place, les voies de re-médiation et de recours, et finalement, comment l’association donne du pouvoir d’agir aux jeunes qui forment la force vive de ce projet

Metastatic mesenchymal chondrosarcoma showing a sustained response to cabozantinib: A case report

Mesenchymal chondrosarcoma is a rare and aggressive sarcoma subtype with high risk for distant metastases and poor prognosis. Currently NCCN- and ESMO-Guidelines recommend using Ewing sarcoma protocols as standard treatment. Nevertheless, in localized disease overall 5-year survival rates are below 50% whereas in metastatic spread median progression-free survival rates of only 5 months can be expected. Here we present a patient with metastatic osseous spread of mesenchymal chondrosarcoma that showed a sustained clinical improvement and a good partial response on imaging over a period of one year when treated with the multi-tyrosine kinase inhibitor cabozantinib. Although we cannot explain the exact mechanism underlying this treatment effect, tumors with similar genetic patterns might respond to the same therapy as well. Keywords: cabozantinib; case report; mesenchymal chondrosarcoma; metastatic disease; p16 loss; tyrosine kinase inhibitors

NTRK fusions in osteosarcoma are rare and non-functional events

Neurotrophic tyrosine receptor kinase (NTRK) fusions are promising molecular targets that have been described in a broad range of malignant tumours. Fusions commonly lead to the expression of chimeric proteins with constitutive tyrosine kinase activation that drives tumorigenesis. Despite a low prevalence among most solid tumours (<1%), the first encouraging results with pan-NTRK tyrosine kinase inhibitors (TKIs) such as larotrectinib or entrectinib stimulated the search for eligible patients. Here, we report the first three cases of osteosarcoma harbouring NTRK fusions, among 113 patients sequenced. It is also the first report on NTRK fusions within a tumour type characterised by highly rearranged genomes and abundant passenger mutations. Whereas the presence of NTRK gene fusions in many tumours is considered to be one of the main driver events for tumour progression, the three chimeric transcripts described here appear non-functional and likely represent randomly occurring passenger alterations. Particularly in tumours with complex karyotypes, it may therefore be advisable to specifically investigate the fusion transcripts for functional impact before considering targeted treatment approaches using pan-NTRK TKIs

Methylation and copy number profiling : emerging tools to differentiate osteoblastoma from malignant mimics?

Rearrangements of the transcription factors FOS and FOSB have recently been identified as the genetic driver event underlying osteoid osteoma and osteoblastoma. Nuclear overexpression of FOS and FOSB have since then emerged as a reliable surrogate marker despite limitations in specificity and sensitivity. Indeed, osteosarcoma can infrequently show nuclear FOS expression and a small fraction of osteoblastomas seem to arise independent of FOS/FOSB rearrangements. Acid decalcification and tissue preservation are additional factors that can negatively influence immunohistochemical testing and make diagnostic decision-making challenging in individual cases. Particularly aggressive appearing osteoblastomas, also referred to as epithelioid osteoblastomas, and osteoblastoma-like osteosarcoma can be difficult to distinguish, underlining the need for additional markers to support the diagnosis. Methylation and copy number profiling, a technique well established for the classification of brain tumors, might fill this gap. Here, we set out to comprehensively characterize a series of 77 osteoblastomas by immunohistochemistry, fluorescence in-situ hybridization as well as copy number and methylation profiling and compared our findings to histologic mimics. Our results show that osteoblastomas are uniformly characterized by flat copy number profiles that can add certainty in reaching the correct diagnosis. The methylation cluster formed by osteoblastomas, however, so far lacks specificity and can be misleading in individual cases

AAV-mediated Gene Therapy Halts Retinal Degeneration in PDE6β-deficient Dogs

International audienceWe previously reported that subretinal injection of AAV2/5 RK.cpde6β allowed long-term preservation of photoreceptor function and vision in the rod-cone dysplasia type 1 (rcd1) dog, a large animal model of naturally occurring PDE6β deficiency. The present study builds on these earlier findings to provide a detailed assessment of the long-term effects of gene therapy on the spatiotemporal pattern of retinal degeneration in rcd1 dogs treated at 20 days of age. We analyzed the density distribution of the retinal layers and of particular photoreceptor cells in 3.5-year-old treated and untreated rcd1 dogs. Whereas no rods were observed outside the bleb or in untreated eyes, gene transfer halted rod degeneration in all vector-exposed regions. Moreover, while gene therapy resulted in the preservation of cones, glial cells and both the inner nuclear and ganglion cell layers, no cells remained in vector-unexposed retinas, except in the visual streak. Finally, the retinal structure of treated 3.5-year-old rcd1 dogs was identical to that of unaffected 4-month-old rcd1 dogs, indicating near complete preservation. Our findings indicate that gene therapy arrests the degenerative process even if intervention is initiated after the onset of photoreceptor degeneration, and point to significant potential of this therapeutic approach in future clinical trials

Vitrectomy Before Intravitreal Injection of AAV2/2 Vector Promotes Efficient Transduction of Retinal Ganglion Cells in Dogs and Nonhuman Primates

International audienceRecombinant adeno-associated virus (AAV) has emerged as a promising vector for retinal gene delivery to restore visual function in certain forms of inherited retinal dystrophies. Several studies in rodent models have shown that intravitreal injection of the AAV2/2 vector is the optimal route for efficient retinal ganglion cell (RGC) transduction. However, translation of these findings to larger species, including humans, is complicated by anatomical differences in the eye, a key difference being the comparatively smaller volume of the vitreous chamber in rodents. Here, we address the role of the vitreous body as a potential barrier to AAV2/2 diffusion and transduction in the RGCs of dogs and macaques, two of the most relevant preclinical models. We intravitreally administered the AAV2/2 vector carrying the CMV-eGFP reporter cassette in dog and macaque eyes, either directly into the vitreous chamber or after complete vitrectomy, a surgical procedure that removes the vitreous body. Our findings suggest that the vitreous body appears to trap the injected vector, thus impairing the diffusion and transduction of AAV2/2 to inner retinal neurons. We show that vitrectomy before intravitreal vector injection is an effective means of overcoming this physical barrier, improving the transduction of RGCs in dog and macaque retinas. These findings support the use of vitrectomy in clinical trials of intravitreal gene transfer techniques targeting inner retinal neurons