Distinct IDH1/2-associated Methylation Profile and Enrichment of TP53 and TERT Mutations Distinguish Dedifferentiated Chondrosarcoma from Conventional Chondrosarcoma

Methylation Analysis Reveals Epigenetic Congruence Between Bone Sarcomas With H3-3A Mutations and Malignant Giant Cell Tumors of Bone

Hotspot mutations in H3-3A gene are key drivers in giant cell tumor of bone (GCTB). Rare primary bone sarcomas also harbor this mutation, but their clinicopathologic characteristics and molecular profiles, as well as their relationship to conventional and malignant GCTB (MGCTB) and high-grade conventional osteosarcoma (HGOS), are largely undefined. Herein, we present a series of 10 H3-3A mutated bone sarcomas (BSH3-3A) with a comparative clinicopathologic, mutational, and epigenetic analysis with conventional GCTB, MGCTB, and HGOS. BSH3-3A comprised of 6 high-grade osteosarcomas, 4 undifferentiated pleomorphic sarcoma of bone and occurred in 7 women and 3 men with a mean age of 46 years (28-74 years). The tumors involved femur (n = 4), talus (n = 2), spine (n = 2), pelvis (n = 1), and 1 unknown site. Epiphysis involvement was noted in 2 femoral tumors. In majority of the cases, BSH3-3A showed cellular proliferation of epithelioid and/or spindle cells, hyperchromatic nuclei, and conspicuous pleomorphism with or without osteoid production. One case exhibited both low- and high-grade osteosarcoma components. The mutational profile of BSH3-3A was different than that of conventional HGOS with significantly less frequent TP53 mutations. The genomic index, which reflects the degree of genomic complexity, was also significantly lower in BSH3-3A compared with HGOS, yet higher than GCTB. DNA methylation analysis revealed that most BSH3-3A and MGCTB cases form a distinct cluster, positioned near but separate from GCTB, and clearly separated from HGOS. Differential methylation analysis revealed that BSH3-3A exhibited the highest degree of similarity to MGCTB in comparison to HGOS and GCTB. Survival analysis showed that outcomes for BSH3-3A do not differ significantly from those observed in HGOS or MGCTB. Finally, BSH3-3A tumors, although radiologically and histologically identical to high-grade bone sarcomas lacking H3-3A mutations, display epigenetic features similar to MGCTB and have a significantly less complex genomic profile than HGOS, despite comparable clinical outcomes.

Role of malate dehydrogenase 1 and isocitrate dehydrogenase 1 and their posttranslational modifications in diseases

Malate dehydrogenase 1 (MDH1) and isocitrate dehydrogenase 1 (IDH1) are two crucial enzymes in the process of energy metabolism. MDH1 plays a crucial role in the malate-aspartate shuttle in the cytoplasm by utilizing the coenzyme NAD/NADH to catalyze the interconversion of malate and oxaloacetate. IDH1 utilizes the coenzyme NADP/NADPH to facilitate the reciprocal transformation between isocitrate and α-ketoglutarate and plays a significant role in the metabolic processes of carbohydrates, lipids, and proteins in the liver. MDH1 and IDH1, along with their posttranslational modifications such as methylation and acetylation can influence the development of many diseases. This article reviews the function of MDH1, IDH1, and their posttranslational changes in various illnesses, aiming to offer new perspectives on disease diagnosis and therapy.

Cartilage Forming Tumors of the Skeleton

Cartilage-forming tumors are a broad and diverse group of neoplasms frequently affecting the skeleton. Distinguishing between the members of this group is important because of significant differences in treatment and prognosis. Accurate diagnosis can be challenging because of similarities in their clinical, radiographic, and pathologic features. Immunohistochemistry and molecular tools are helpful in select instances. Therefore, careful evaluation and correlation of these features are essential in arriving at the correct diagnosis and appropriate patient management. This review provides an overview of the current literature, emphasizing helpful features in diagnosis.

[Rare forms of dedifferentiated chondrosarcomas: About 3 cases]

Conventional chondrosarcoma is the most common primary malignant bone tumor in adults. Dedifferentiated chondrosarcomas represent 10 to 15% of conventional chondrosarcomas and constitute a high-grade subtype with a poor prognosis, with a 5-year survival rate of 24%. These tumors are characterized by a mutation in one of the isocitrate dehydrogenase (IDH) 1 or 2 genes in 70% of cases. Histological diagnosis requires a biphasic morphology combining a low-grade conventional chondrosarcoma component with a high-grade non-cartilaginous sarcomatoid component. In the literature, this dedifferentiated component most often corresponds to an osteosarcoma or an undifferentiated sarcomatous component. This article describes three cases of dedifferentiated chondrosarcomas: two with bone localization and one with laryngeal cartilaginous localization presenting a rare dedifferentiation component, either epithelial or rhabdomyosarcomatous, which may pose a diagnostic challenge, particularly in micro-biopsy samples. The mechanism of dedifferentiation is still poorly understood, and the origin of the dedifferentiated component remains controversial.

Chondrosarcoma: New Molecular Insights, Challenges in Near-Patient Preclinical Modeling, and Therapeutic Approaches

Chondrosarcoma (CS), the second most common malignant bone tumor after osteosarcoma, accounts for 20-30% of all malignant bone tumors. It mainly affects adults, middle-aged, and elderly people. The CS family includes various entities displaying peculiar biological, genetic, and epigenetic characteristics and clinical behaviors. Conventional CS is the most common subtype. High-grade, dedifferentiated, and mesenchymal CS, as well as unresectable and metastatic CS, exhibit poor prognoses due to their intrinsic resistance to radiotherapy and chemotherapy, underscoring the urgent need for novel therapeutic strategies. CS research is dealing with several challenges. Experimental studies can rely on animal and patient-derived models, but the paucity of representative near-patient preclinical models has hampered predictive drug screening research. This review describes the main clinical and molecular features of CS subtypes, discussing recent data on the genetic alterations and molecular mechanisms involved in CS pathogenesis and progression. The review provides an overview of the current in vitro and in vivo CS models, discusses their advantages and limitations, and highlights the recent efforts in the development of new targeted therapies against CS dependencies, including IDH1/2 mutations, NAD+ dependency, and SIRT1-HIF-2α axis, or exploring DR5 targeting, antiangiogenic therapies, epigenetic drugs, and immunological approaches. All such strategies, in combination with advanced preclinical modeling and personalized multi-omic profiling, hold promise for improving the survival of patients with advanced CS.

IDH1/2 Mutations in Cancer: Unifying Insights and Unlocking Therapeutic Potential for Chondrosarcoma

Chondrosarcomas, a rare form of bone sarcomas with multiple subtypes, pose a pressing clinical challenge for patients with advanced or metastatic disease. The lack of US Food and Drug Administration (FDA)-approved medications underscores the urgent need for further research and development in this area. Patients and their families face challenges as there are no systemic therapeutic options available with substantial effectiveness. A significant number (50-80%) of chondrosarcomas have a mutation in the isocitrate dehydrogenase (IDH) genes. This review focuses on IDH-mediated pathogenesis and recent pharmacological advances with novel IDH inhibitors, explores their potential therapeutic value, and proposes potential future avenues for clinical trials combining IDH inhibitors with other systemic agents for chondrosarcomas.

Nivolumab and sunitinib in patients with advanced bone sarcomas: A multicenter, single-arm, phase 2 trial

BACKGROUND

Herein, we present the results of the phase 2 IMMUNOSARC study (NCT03277924), investigating sunitinib and nivolumab in adult patients with advanced bone sarcomas (BS).

METHODS

Progressing patients with a diagnosis of BS were eligible. Treatment was comprised of sunitinib (37.5 mg/day on days 1-14, 25 mg/day afterword) plus nivolumab (3 mg/kg every 2 weeks). Primary end point was progression-free survival rate (PFSR) at 6 months based on central radiology review. Secondary end points were overall survival (OS), overall response rate (ORR) by Response Evaluation Criteria in Solid Tumors (RECIST) v1.1, and safety.

RESULTS

A total of 46 patients were screened, 40 patients entered the study, and 38 underwent central radiological review and were evaluable for primary end point. Median age was 47 years (range, 21-74). Histologies include 17 (43%) osteosarcoma, 14 chondrosarcoma (35%, 10 conventional, four dedifferentiated [DDCS]), eight (20%) Ewing sarcoma, and one (2%) undifferentiated pleomorphic sarcoma. The PFSR at 6 months was 42% (95% confidence interval [CI], 27-58). With a median follow-up of 39.8 months (95% CI, 37.9-41.7), the median PFS and OS were 3.8 months (95% CI, 2.7-4.8) and 11.9 months (95% CI, 5.6-18.2). ORR by RECIST was 5%, with two of 38 partial responses (one of four DDCS and one of 17 osteosarcoma), 19 of 38 (50%) stable disease, and 17 of 38 (45%) progressions. Grade ≥3 adverse events were neutropenia (six of 40, 15%), anemia (5/40, hypertension (6/40, 15%), 12.5%), ALT/AST elevation (5/40, 12.5%), and pneumonitis (1/40, 2.5%). Seventeen percent of patients discontinued treatment due to toxicity, including a treatment-related grade 5 pneumonitis CONCLUSION: The trial met its primary end point in the BS cohort with >15% of patients progression-free at 6 months. However, the toxicity profile of this regimen was relevant.

Global research development of chondrosarcoma from 2003 to 2022: a bibliometric analysis

Background

Chondrosarcomas are common primary malignant bone tumors; however, comprehensive bibliometric analysis in this field has not yet been conducted. Therefore, this study aimed to explore the research hotspots and trends in the field of chondrosarcoma through bibliometric analysis to help researchers understand the current status and direction of research in the field.

Methods

Articles and reviews related to chondrosarcoma published between 2003 and 2022 were retrieved from the Web of Science. Countries, institutions, authors, journals, references, and keywords in this field were visualized and analyzed using CtieSpace and VOSviewer software.

Results

Between 2003 and 2022, 4,149 relevant articles were found. The number of articles published on chondrosarcoma has increased significantly annually, mainly from 569 institutions in China and the United States, and 81 in other countries. In total, 904 authors participated in the publication of studies related to chondrosarcomas. Over the past 20 years, articles on chondrosarcoma have been published in 958 academic journals, with Skeletal Radiology having the highest number of publications. Furthermore, keywords such as "gene expression," "radiotherapy," "experience," and "apoptosis" have been popular in recent years.

Conclusion

Over the past 20 years, the global trend in chondrosarcoma research has primarily been clinical research, with basic research as a supplement. In the future, communication and exchange between countries and institutions should be strengthened. Further, the future main research hotspots in the field of chondrosarcoma include mutated genes and signaling pathways, precision surgical treatment, proton therapy, radiation therapy, chemotherapy, immunotherapy, and other aspects.

A personalized medicine approach identifies enasidenib as an efficient treatment for IDH2 mutant chondrosarcoma

BACKGROUND

Sarcomas represent an extensive group of malignant diseases affecting mesodermal tissues. Among sarcomas, the clinical management of chondrosarcomas remains a complex challenge, as high-grade tumours do not respond to current therapies. Mutations in the isocitrate dehydrogenase (IDH) 1 and 2 genes are among the most common mutations detected in chondrosarcomas and may represent a therapeutic opportunity. The presence of mutated IDH (mIDH) enzymes results in the accumulation of the oncometabolite 2-HG leading to molecular alterations that contribute to drive tumour growth.

METHODS

We developed a personalized medicine strategy based on the targeted NGS/Sanger sequencing of sarcoma samples (n = 6) and the use of matched patient-derived cell lines as a drug-testing platform. The anti-tumour potential of IDH mutations found in two chondrosarcoma cases was analysed in vitro, in vivo and molecularly (transcriptomic and DNA methylation analyses).

FINDINGS

We treated several chondrosarcoma models with specific mIDH1/2 inhibitors. Among these treatments, only the mIDH2 inhibitor enasidenib was able to decrease 2-HG levels and efficiently reduce the viability of mIDH2 chondrosarcoma cells. Importantly, oral administration of enasidenib in xenografted mice resulted in a complete abrogation of tumour growth. Enasidenib induced a profound remodelling of the transcriptomic landscape not associated to changes in the 5 mC methylation levels and its anti-tumour effects were associated with the repression of proliferative pathways such as those controlled by E2F factors.

INTERPRETATION

Overall, this work provides preclinical evidence for the use of enasidenib to treat mIDH2 chondrosarcomas.

FUNDING

Supported by the Spanish Research Agency/FEDER (grants PID2022-142020OB-I00; PID2019-106666RB-I00), the ISC III/FEDER (PI20CIII/00020; DTS18CIII/00005; CB16/12/00390; CB06/07/1009; CB19/07/00057); the GEIS group (GEIS-62); and the PCTI (Asturias)/FEDER (IDI/2021/000027).

Dedifferentiated Chondrosarcoma from Molecular Pathology to Current Treatment and Clinical Trials

Dedifferentiated chondrosarcoma (DDCS) is a rare subtype of chondrosarcoma, a primary cartilaginous malignant neoplasm. It accounts for up to 1-2% of all chondrosarcomas and is generally associated with one of the poorest prognoses among all chondrosarcomas with the highest risk of metastasis. The 5-year survival rates range from 7% to 24%. DDCS may develop at any age, but the average presentation age is over 50. The most common locations are the femur, pelvis humerus, scapula, rib, and tibia. The standard treatment for localised disease is surgical resection. Most patients are diagnosed in unresectable and advanced stages, and chemotherapy for localised and metastatic dedifferentiated DDCS follows protocols used for osteosarcoma.

The spectrum and significance of secondary (co-occurring) genetic alterations in sarcomas: the hallmarks of sarcomagenesis

Bone and soft tissue tumors are generally classified into complex karyotype sarcomas versus those with recurrent genetic alterations, often in the form of gene fusions. In this review, we provide an overview of important co-occurring genomic alterations, organized by biological mechanisms and covering a spectrum of genomic alteration types: mutations (single-nucleotide variations or indels) in oncogenes or tumor suppressor genes, copy number alterations, transcriptomic signatures, genomic complexity indices (e.g. CINSARC), and complex genomic structural variants. We discuss the biological and prognostic roles of these so-called secondary or co-occurring alterations, arguing that recognition and detection of these alterations may be significant for our understanding and management of mesenchymal tumors. On a related note, we also discuss major recurrent alterations in so-called complex karyotype sarcomas. These secondary alterations are essential to sarcomagenesis via a variety of mechanisms, such as inactivation of tumor suppressors, activation of proliferative signal transduction, telomere maintenance, and aberrant regulation of epigenomic/chromatin remodeling players. The use of comprehensive genomic profiling, including targeted next-generation sequencing panels or whole-exome sequencing, may be incorporated into clinical workflows to offer more comprehensive, potentially clinically actionable information. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.