Mesenchymal chondrosarcoma diagnosed on FISH for HEY1-NCOA2 fusion gene

Mesenchymal Chondrosarcoma from Diagnosis to Clinical Trials

Mesenchymal chondrosarcoma (MCS) is a rare subtype of chondrosarcoma with a poor prognosis. Although these tumors are sensitive to radiotherapy/chemotherapy, the standard treatment for localized MCS is only surgical resection, and there are no established treatment guidelines for patients with advanced and metastatic MCS. Due to the low incidence of MCS, the pathology of these tumors is still unknown, and other therapeutic options are lacking. Some studies show the potential role of the PDGF/PPI3K/AKT, PKC/RAF/MEK/ERK, and pRB pathways, and BCL2 overexpression in the pathogenesis of MCS. These findings provide an opportunity to use protein kinases and BCL2 inhibitors as potential therapy in MCS. In this review, we summarize the current knowledge about MCS diagnosis and treatment options. We show the immunological and molecular biomarkers used in the diagnosis of MCS. In addition, we discuss the known prognostic and predictive factors in MCS. Finally, we present the novel trends, including targeted therapies and ongoing clinical trials using protein kinase inhibitors and the death receptor 5 (DR5) agonist, which may be the focus of future MCS treatment studies.

Genomic profiling identifies genes and pathways dysregulated by HEY1-NCOA2 fusion and shines a light on mesenchymal chondrosarcoma tumorigenesis

Mesenchymal chondrosarcoma is a rare, high‐grade, primitive mesenchymal tumor. It accounts for around 2–10% of all chondrosarcomas and mainly affects adolescents and young adults. We previously described the HEY1–NCOA2 as a recurrent gene fusion in mesenchymal chondrosarcoma, an important breakthrough for characterizing this disease; however, little study had been done to characterize the fusion protein functionally, in large part due to a lack of suitable models for evaluating the impact of HEY1–NCOA2 expression in the appropriate cellular context. We used iPSC‐derived mesenchymal stem cells (iPSC‐MSCs), which can differentiate into chondrocytes, and generated stable transduced iPSC‐MSCs with inducible expression of HEY1–NCOA2 fusion protein, wildtype HEY1 or wildtype NCOA2. We next comprehensively analyzed both the DNA binding properties and transcriptional impact of HEY1–NCOA2 expression by integrating genome‐wide chromatin immunoprecipitation sequencing (ChIP‐seq) and expression profiling (RNA‐seq). We demonstrated that HEY1–NCOA2 fusion protein preferentially binds to promoter regions of canonical HEY1 targets, resulting in transactivation of HEY1 targets, and significantly enhances cell proliferation. Intriguingly, we identified that both PDGFB and PDGFRA were directly targeted and upregulated by HEY1‐NCOA2; and the fusion protein, but not wildtype HEY1 or NCOA2, dramatically increased the level of phospho‐AKT (Ser473). Our findings provide a rationale for exploring PDGF/PI3K/AKT inhibition in treating mesenchymal chondrosarcoma. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Interstitial Deletions Generating Fusion Genes

A fusion gene is the physical juxtaposition of two different genes resulting in a structure consisting of the head of one gene and the tail of the other. Gene fusion is often a primary neoplasia-inducing event in leukemias, lymphomas, solid malignancies as well as benign tumors. Knowledge about fusion genes is crucial not only for our understanding of tumorigenesis, but also for the diagnosis, prognostication, and treatment of cancer. Balanced chromosomal rearrangements, in particular translocations and inversions, are the most frequent genetic events leading to the generation of fusion genes. In the present review, we summarize the existing knowledge on chromosome deletions as a mechanism for fusion gene formation. Such deletions are mostly submicroscopic and, hence, not detected by cytogenetic analyses but by array comparative genome hybridization (aCGH) and/or high throughput sequencing (HTS). They are found across the genome in a variety of neoplasias. As tumors are increasingly analyzed using aCGH and HTS, it is likely that more interstitial deletions giving rise to fusion genes will be found, significantly impacting our understanding and treatment of cancer.

Intracranial extra-axial mesenchymal chondrosarcoma in a 16-month-old patient with a literature review of pediatric patients

Mesenchymal chondrosarcoma is a rare high-grade malignant subtype of chondrosarcoma that is characterized by undifferentiated, round, or spindled mesenchymal cells, interspersed with islands of hyaline cartilage. We report a primary intracranial extra-axial mesenchymal chondrosarcoma in a 16-month-old patient with a review of the literature focusing on intracranial extra-axial MCs with or without skull involvement in pediatric patients, including differential diagnosis. The patient was admitted with a swelling in the right temporooccipital region. There was intracranial extra-dural extension of the mass, which abuts the neural parenchyma without any invasion. A complete tumor resection was performed. Pathological diagnosis was mesenchymal chondrosarcoma. The patient was free of symptoms after surgery.

Primary mesenchymal chondrosarcoma of the kidney without HEY1-NCOA2 and IRF2BP2-CDX1 fusion: A case report and review

Mesenchymal chondrosarcoma (MC) of the kidney is rare. To the best of our knowledge, the current report is the first case of a giant extraskeletal MC that arose primarily from the right kidney and mimicked renal cell carcinoma at the locally advanced stage (cT3bN0) with vena cava thrombus and multiple pulmonary arterial tumor emboli. Additionally, the literature on renal EMC is reviewed and the possibilities of oncogenic heterogeneity are discussed. A 64-year-old woman was admitted to Yamagata University Hospital for sudden onset of asymptomatic gross hematuria. CT revealed a 90 mm renal mass without calcification in the right kidney and tumor thrombus extending to the inferior vena cava. Radical nephrectomy with thrombectomy was performed. Lung metastasis was detected 2 months later. The patient received systemic chemotherapy, which was only marginally effective. She died of the malignancy 8 months after surgery. Microscopic examination of the tumor revealed typical histology of MC and a lack of HEY1-NCOA2 and IRF2BP2-CDX1 gene fusions in the tumor tissues. Not all MC patients may exhibit chromosomal alterations in the tumor, suggesting the presence of genetically heterogeneous pathways of MC oncogenesis. Further studies are required to confirm the present findings and reinforce the molecular diagnosis of MC.

Mesenchymal Chondrosarcoma: a Review with Emphasis on its Fusion-Driven Biology

Mesenchymal chondrosarcoma is a rare but deadly form of chondrosarcoma that typically affects adolescents and young adults. While curative intent is possible for patients with localized disease, few options exist for patients in the unresectable/metastatic setting. Thus, it is imperative to understand the fusion-driven biology of this rare malignant neoplasm so as to lead to the future development of better therapeutics for this disease. This manuscript will briefly review the clinical and pathologic features of mesenchymal chondrosarcoma followed by an appraisal of existing data linked to the fusions, HEY1-NCOA2 and IRF2BP2-CDX1, and the associated downstream pathways.

An update on mesenchymal tumours of the orbit with an emphasis on the value of molecular/cytogenetic testing

Mesenchymal tumours of the orbit are uncommon. Beyond childhood primary sarcomas are extremely rare and the literature is limited to case reports and short case series. However there is a diverse assortment of benign and malignant soft tissue tumours that may involve the orbit. Techniques to identify tumour specific cytogenetic or molecular genetic abnormalities often resulting in over- expressed proteins are becoming an increasingly important ancillary technique for these tumours. This review focuses on 3 specific areas: 1. Orbital mesenchymal tumours where cytogenetics are important to reach the correct diagnosis. The majority of these are chromosomal translocations that often result in a fusion gene and protein product; 2. Orbital mesenchymal tumours where cytogenetics are important to identify patients who will do well versus those with a poorer prognosis. This is turn helps with therapeutic options. In some tumours e.g. synovial sarcoma the chromosomal translocations can occur with 2 different regions resulting in different fusion products that carry a different prognosis. Alternatively whilst the majority of alveolar rhadomyosarcomas are fusion positive a minority are fusion negative with a better prognosis; 3. Orbital mesenchymal tumours where the identification of specific cytogenetic abnormalities has resulted in overexpression of specfic proteins which are diagnostically useful biomarkers for immunohistochemistry.

Advances in chromosomal translocations and fusion genes in sarcomas and potential therapeutic applications

Chromosomal translocations and fusion genes are very common in human cancer especially in subtypes of sarcomas, such as rhabdomyosarcoma, Ewing's sarcoma, synovial sarcoma and liposarcoma. The discovery of novel chromosomal translocations and fusion genes in different tumors are due to the advancement of next-generation sequencing (NGS) technologies such as whole genome sequencing. Recently, many novel chromosomal translocations and gene fusions have been identified in different types of sarcoma through NGS approaches. In addition to previously known sarcoma fusion genes, these novel specific fusion genes and associated molecular events represent important targets for novel therapeutic approaches in the treatment of sarcomas. This review focuses on recent advances in chromosomal translocations and fusion genes in sarcomas and their potential therapeutic applications in the treatment of sarcomas.

Pancreatic involvement by mesenchymal chondrosarcoma harboring the HEY1-NCOA2 gene fusion

Mesenchymal chondrosarcoma (MC) is an aggressive small, round, blue cell tumor with chondrogenic differentiation that typically arises in bony sites. Approximately, a third of these tumors develop in extraskeletal sites such as the meninges, and somatic soft tissue. The MCs are well-circumscribed, lobulated masses, with focal calcification. Histologically, 2 distinct populations of neoplastic cells characterize MC: sheets of primitive small, round, blue cells surrounding islands of well-developed hyaline cartilage with mature chondrocytes in lacunae. Involvement of the gastrointestinal tract and pancreas by primary or metastatic MC is a relatively rare occurrence. We identified 8 patients with MC in our departmental archives from 1990 to 2015, two of which had pancreatic involvement. The patients were young women who developed masses in the distal pancreas. Molecular testing demonstrated that both tumors harbored the recently described HEY1-NCOA2 gene fusion. These cases illustrate that pancreatic involvement can occur in MC, and the demonstration of HEY1-NCOA2 fusion can be helpful to confirm the diagnosis.