HMGA2 is the partner of MDM2 in well-differentiated and dedifferentiated liposarcomas whereas CDK4 belongs to a distinct inconsistent amplicon

Discovery of a dual-target DYRK2 and HDAC8 inhibitor for the treatment of hepatocellular carcinoma

Dual-specificity tyrosine phosphorylation-regulated kinase 2 (DYRK2) and histone deacetylase 8 (HDAC8) have been shown to be associated with the development of several cancers. Here, we identified a dual-target DYRK2/HDAC8 inhibitor (DYC-1) through a combined virtual screening protocol. DYC-1 exhibited nanomolar inhibitory activity against both DYRK2 (IC50 = 5.27 ± 0.13 nM) and HDAC8 (IC50 = 8.06 ± 0.47 nM). Molecular dynamics simulations showed that DYC-1 had positive binding stability with DYRK2 and HDAC8. Importantly, the cytotoxicity assay indicated that DYC-1 exhibited superior antiproliferative activity against human liver cancer, especially SK-HEP-1 cells, and had no significant inhibition on normal liver cells. Moreover, DYC-1 showed a strong inhibitory effect on the growth of SK-HEP-1 xenograft tumors with no significant side effects. These data suggest that DYC-1 is a high-efficacy and low-toxic antitumor agent for the treatment of hepatocellular carcinoma.

An overview on liposarcoma subtypes: Genetic alterations and recent advances in therapeutic strategies

Liposarcoma (LPS) is a rare malignancy of adipocytic differentiation. According to World Health Organization classification, LPS comprises of four principle subtypes Atypical lipomatous tumor/Well-differentiated liposarcoma (ATL/WDLPS), Dedifferentiated liposarcoma (WDLPS), Myxoid liposarcoma (MLPS), and Pleomorphic liposarcoma (PLPS). Each subtype can develop at any location and shows distinct clinical behavior and treatment sensitivity. ATL/ WDLPS subtype has a higher incidence rate, low recurrence, and is insensitive to radiation and chemotherapy. DDLPS is the focal progression of WDLPS, which is aggressive and highly metastasizing. MLPS is sensitive to radiation and chemotherapy, with a higher recurrence rate and metastasis. PLPS subtype is highly metastasizing, has a poor prognosis, and exhibiting higher recurrence rate. Initial histological analysis provides information for the characterization of LPS subtypes', further molecular and genetic analysis provides certain subtype specifications, such as gene amplifications and gene fusions. Such molecular genetic alterations will be useful as therapeutic targets in various cancers, including the LPS subtypes. A wide range of novel therapeutic agents based on genetic alterations that aim to target LPS subtypes specifically are under investigation. This review summarizes the LPS subtype classification, their molecular genetic characteristics, and the implications of genetic alterations in therapeutics.

Opportunity in Complexity: Harnessing Molecular Biomarkers and Liquid Biopsies for Personalized Sarcoma Care

Due to their rarity and complexity, sarcomas represent a substantial therapeutic challenge. However, the incredible diversity within and across sarcoma subtypes presents an opportunity for personalized care to maximize efficacy and limit toxicity. A deeper understanding of the molecular alterations that drive sarcoma development and treatment response has paved the way for molecular biomarkers to shape sarcoma treatment. Genetic, transcriptomic, and protein biomarkers have become critical tools for diagnosis, prognostication, and treatment selection in patients with sarcomas. In the future, emerging biomarkers like circulating tumor DNA analysis offer the potential to improve early detection, monitoring response to treatment, and identifying mechanisms of resistance to personalize sarcoma treatment. Here, we review the current state of molecular biomarkers for sarcomas and highlight opportunities and challenges for the implementation of new technologies in the future.

DDIT3-amplified or low-polysomic pleomorphic sarcomas without MDM2 amplification: Clinicopathological review and immunohistochemical profile of nine cases

Several high-grade pleomorphic sarcoma cases that cannot be classified into any existing established categories have been reported. These cases were provisionally classified into undifferentiated pleomorphic sarcoma (UPS). Some dedifferentiated liposarcoma (DDLS) cases may also have been classified into the UPS category due to the absence of MDM2 amplification or an atypical lipomatous tumor/well-differentiated liposarcoma component. We retrieved and reviewed 77 high-grade pleomorphic sarcoma cases, initially diagnosed as UPS in 66 cases and DDLS in 11 cases. Fluorescence in situ hybridization (FISH) analyses of DDIT3 and MDM2 were performed for available cases. Of the cases successfully subjected to DDIT3 FISH (n = 56), nine (7 UPS and 2 DDLS) showed DDIT3 amplification but no MDM2 amplification. Two UPS cases showed both telomeric (5') and centromeric (3') amplification of DDIT3 or low polysomy of chromosome 12, whereas 5 UPS and 2 DDLS cases showed 5'-predominant DDIT3 amplification. Histopathologically, all cases showed UPS-like proliferation of atypical pleomorphic tumor cells. Immunohistochemically, only one case showed focal nuclear positivity for DDIT3, supporting the previous finding that DDIT3 expression was not correlated with DDIT3 amplification. All three cases with focal MDM2 expression involved 5'-predominant amplification, two of which showed DDLS-like histological features. The majority of cases (7/9) showed decreased expression in p53 staining, suggesting that DDIT3 amplification regulates the expression of TP53 like MDM2. From a clinicopathological perspective, we hypothesize that DDIT3-amplified sarcoma, especially with 5'-predominant amplification, can be reclassified out of the UPS category.

Uterine MEIS1::NCOA2 Fusion Sarcoma With Lung Metastasis: A Case Report and Review of the Literature

MEIS1::NCOA1/2 fusion sarcomas are a recently described novel entity arising in a variety of locations with a predilection for the genitourinary tract and gynecologic organs. Despite multiple locoregional recurrences, these tumors are thought to behave in a low-grade malignant manner. Here we report a uterine MEIS1::NCOA2 fusion sarcoma with lung metastasis. The patient was a 47-yr-old woman with a history of abnormal uterine bleeding who was found to have a myometrial mass confirmed by pathology to be uterine sarcoma. The tumor was predominantly composed of monotonous spindle cells with scant cytoplasm, crowded nuclei, and brisk mitotic activity, growing in a fascicular and streaming pattern. The morphologic and immunophenotypic features were nonspecific and a diagnosis of high-grade uterine sarcoma with a differential of leiomyosarcoma versus high-grade endometrial stromal sarcoma was rendered. At the 27-mo follow-up, the patient was found to have a lung metastasis consisting of a monotonous round cell sarcoma. A retrospective RNA-based and DNA-based next-generation sequencing of the primary uterine sarcoma revealed a MEIS1::NCOA2 gene fusion, a c.94G>C/p.D32H mutation in exon 3 of CTNNB1 gene, HMGA2 , and CDK4 gene amplification, and an intermediate/marginal level of MDM2 gene amplification. Polymerase chain reaction-based molecular analysis further demonstrated that the MEIS1::NCOA2 gene fusion and CTNNB1 somatic mutation were also present in the lung metastasis. This case represents the first case of such gynecologic sarcoma with distant (lung) metastasis, and the second metastatic case among all reported MEIS1::NCOA1/2 fusion sarcomas, highlighting the malignant metastatic potential of this emerging entity. Our case also indicates that HMGA2/CDK4/MDM2 region amplification and CTNNB1 somatic mutation might be recurrent genetic events in this rare sarcoma subtype.

MDM2-p53 in liposarcoma: The need for targeted therapies with novel mechanisms of action

Well-differentiated and dedifferentiated liposarcomas (WDLPS and DDLPS) are rare tumors that arise from lipocytes in soft tissue. There is a high unmet need in patients with these liposarcomas given poor outcomes, particularly for DDLPS. WDLPS and DDLPS share important genetic and histological characteristics - most notably, the amplification of the 2 genes MDM2 and CDK4. Both genes are considered oncogenes because of their ability to shut down tumor suppressor pathways. There are multiple therapeutic approaches that aim to target MDM2 and CDK4 activity for the purpose of restoring intrinsic tumor suppressor cellular response and terminating oncogenesis. However, current understanding of the molecular mechanisms involved in WDLPS and DDLPS pathology is limited. In recent years, significant efforts have been made to refine and implement targeted therapy for this patient population. The use of patient-derived cell and tumor xenograft models has been an important tool for recapitulating WDLPS and DDLPS biology. These models also offer valuable insights for drug development and drug combination studies. Here we offer a review of the current understanding of WDLPS and DDLPS biology and its therapeutic implications.

Unveiling the role of GAS41 in cancer progression

GAS41, a member of the human YEATS domain family, plays a pivotal role in human cancer development. It serves as a highly promising epigenetic reader, facilitating precise regulation of cell growth and development by recognizing essential histone modifications, including histone acetylation, benzoylation, succinylation, and crotonylation. Functional readouts of these histone modifications often coincide with cancer progression. In addition, GAS41 functions as a novel oncogene, participating in numerous signaling pathways. Here, we summarize the epigenetic functions of GAS41 and its role in the carcinoma progression. Moving forward, elucidating the downstream target oncogenes regulated by GAS41 and the developing small molecule inhibitors based on the distinctive YEATS recognition properties will be pivotal in advancing this research field.

Extremely Rare Type of Breast Cancer-Dedifferentiated Breast Liposarcoma-Diagnosis and Treatment

Primary liposarcoma of the breast is an uncommon soft tissue malignant tumor, comprising only 0.003% of all malignant breast tumors. The main differential diagnosis of this mass consists of malignant phyllodes tumor and metaplastic breast carcinoma. The objective of this paper is to report a case of dedifferentiated breast liposarcoma, therapeutic approach and outcome. We present a case of a 79-year-old woman complaining of a large mass in her left breast which had increased in size over the last 6 months. Physical examination revealed an enlarged left breast, and a total body CT scan showed a large tumor in contact with the musculature of the anterior thoracic wall, with no metastatic lesions. The histopathology report of a fine needle biopsy described a high-grade sarcoma. The Oncological Tumor Board recommended neoadjuvant radiotherapy sessions and reevaluation by MRI and CT scans. The patient underwent radical mastectomy with latissimus dorsi myo-cutaneous flap reconstruction. The final histopathology diagnosis was a grade 3 dedifferentiated liposarcoma (FNCLCC), with certain response to radiotherapy and positive MDM2, CDK4 markers. The postoperative period was uneventful; 12 months after surgery, the follow-up CT scan showed multiple pulmonary lesions with metastatic characteristics. Liposarcoma is a very rare type of breast cancer, and the most important treatment for breast sarcoma is surgery, the role of axillary lymph node removal, chemotherapy and radiotherapy still being controversial. Considering such cases are scarce and the development of surgical guidelines is difficult, reporting any new case is crucial.

A century of retroperitoneal soft-tissue sarcoma research: From single center experience to precision oncology? A bibliometric analysis of past, present, and future perspectives

BACKGROUND

Increasing publication numbers in the biomedical field led to an improvement of patient care in many aspects but are challenging for scientists when integratively processing data of their fields. Using bibliometric analyses, the present study assesses the productivity and predominant topics in retroperitoneal soft-tissue sarcoma (RPS) research across the past 122 years, thereby identifying crucial questions to address in future RPS research.

METHODS

Using the Web of Science Core Collection, 1018 RPS-associated publications from 1900 to 2022 were identified and analyzed regarding key bibliometric variables using the Bibliometrix R package and the VOSviewer software.

RESULTS

A continuous increase in RPS-associated publication numbers can be noticed over the time, which is strongly pronounced from 2005 onwards, and is characterized by a multinationally driven collaborative clinical research focus. The research primarily reflects progression regarding surgical techniques, histology-based therapy, radiotherapy regimens, and identification of prognostic clinicopathological factors. This progression is accompanied with improved overall survival of RPS patients. However, a paucity of RPS-specific basic/translational research indicates that such research might be additionally needed to better understand the pathophysiology of RPS and with that to enable the development of personalized therapies and to further improve patient outcome.

CONCLUSION

Increasing publication numbers of multinationally driven clinical RPS research are accompanied with improved overall survival of RPS patients, highlighting the importance of international collaborations to facilitate future clinical trials. However, this bibliometric analysis reveals a lack of RPS-specific basic/translational research which is needed to further improve patient outcome in the context of precision oncology.

Mechanistic insights into genomic structure and functions of a novel oncogene YEATS4

As a novel oncogene, the role of YEATS domain-containing protein 4 (YEATS4) in the occurrence, development, and treatment of tumors is now beginning to be appreciated. YEATS4 plays an important role in regulating DNA repair during replication. The upregulation of YEAST4 promotes DNA damage repair and prevents cell death, whereas its downregulation inhibits DNA replication and induces apoptosis. Additionally, accumulating evidence indicates that the aberrant activation of YEATS4 leads to changes in drug resistance, epithelial-mesenchymal transition and also in the migration and invasion capacity of tumor cells. Therefore, specific inhibition of the expression or activity of YEATS4 protein may be an effective strategy for inhibiting the proliferation, motility, differentiation, and/or survival of tumor cells. Taken together, YEATS4 has emerged as a potential target for multiple cancers and is an attractive protein for the development of small-molecule inhibitors. However, research on YEAST4 in tumor-related fields is limited and its biological functions, metabolism, and the regulatory mechanism of YEATS4 in numerous cancers remain undetermined. This review comprehensively and extensively summarizes the functions, structure and oncogenic roles of YEATS4 in cancer progression and aims to further contribute to the study of its underlying molecular mechanism and targeted drugs.

New developments in the pathology and molecular biology of retroperitoneal sarcomas

Retroperitoneal sarcomas (RPS) refer to a heterogeneous group of malignancies of mesenchymal origin developing from retroperitoneal tissues and vessels. The most frequent RPS are well differentiated/dedifferentiated liposarcomas and leiomyosarcomas, but other rare histological subtypes can be observed. Over the last decade, significant advances have been made in the pathological and molecular characterization of sarcomas. These advances have led to major changes in their diagnostic management as well as in the development of new therapeutic strategies based on tumor biology and microenvironment. This review describes the current knowledge and recent findings in the pathology and molecular biology of the most frequent RPS subtypes.

Treatment of De-Differentiated Liposarcoma in the Era of Immunotherapy

Well-differentiated/de-differentiated liposarcoma (WDLPS/DDLPS) is one of the most common histologic subtypes of soft tissue sarcoma (STS); however, treatment options remain limited. WDLPS and DDLPS both exhibit the characteristic amplification of chromosome region 12q13-15, which contains the genes CDK4 and MDM2. DDLPS exhibits higher amplification ratios of these two and carries additional genomic lesions, including the amplification of chromosome region 1p32 and chromosome region 6q23, which may explain the more aggressive biology of DDLPS. WDLPS does not respond to systemic chemotherapy and is primarily managed with local therapy, including multiple resections and debulking procedures whenever clinically feasible. In contrast, DDLPS can respond to chemotherapy drugs and drug combinations, including doxorubicin (or doxorubicin in combination with ifosfamide), gemcitabine (or gemcitabine in combination with docetaxel), trabectedin, eribulin, and pazopanib. However, the response rate is generally low, and the response duration is usually short. This review highlights the clinical trials with developmental therapeutics that have been completed or are ongoing, including CDK4/6 inhibitors, MDM2 inhibitors, and immune checkpoint inhibitors. This review will also discuss the current landscape in assessing biomarkers for identifying tumors sensitive to immune checkpoint inhibitors.

Epigenomic and transcriptomic landscaping unraveled candidate repositioned therapeutics for non-functioning pituitary neuroendocrine tumors

PURPOSE

Non-functioning pituitary neuroendocrine tumors are challengingly diagnosed tumors in the clinic. Transsphenoidal surgery remains the first-line treatment. Despite the development of state-of-the-art techniques, no drug therapy is currently approved for the treatment. There are also no randomized controlled trials comparing therapeutic strategies or drug therapy for the management after surgery. Therefore, novel therapeutic interventions for the therapeutically challenging NF-PitNETs are urgently needed.

METHODS

We integrated epigenome and transcriptome data (both coding and non-coding) that elucidate disease-specific signatures, in addition to biological and pharmacological data, to utilize rational pathway and drug prioritization in NF-PitNETs. We constructed an epigenome- and transcriptome-based PPI network and proposed hub genes. The signature-based drug repositioning based on the integration of multi-omics data was performed.

RESULTS

The construction of a disease-specific network based on three different biological levels revealed DCC, DLG5, ETS2, FOXO1, HBP1, HMGA2, PCGF3, PSME4, RBPMS, RREB1, SMAD1, SOCS1, SOX2, YAP1, ZFHX3 as hub proteins. Signature-based drug repositioning using hub proteins yielded repositioned drug candidates that were confirmed in silico via molecular docking. As a result of molecular docking simulations, palbociclib, linifanib, trametinib, eplerenone, niguldipine, and zuclopenthixol showed higher binding affinities with hub genes compared to their inhibitors and were proposed as potential repositioned therapeutics for the management of NF-PitNETs.

CONCLUSION

The proposed systems' biomedicine-oriented multi-omics data integration for drug repurposing to provide promising results for the construction of effective clinical therapeutics. To the best of our knowledge, this is the first study reporting epigenome- and transcriptome-based drug repositioning for NF-PitNETs using in silico confirmations.

MDM2 for the practicing pathologist: a primer

The mouse double minute 2 (MDM2) gene is located on the long arm of chromosome 12 and is the primary negative regulator of p53. The MDM2 gene encodes an E3 ubiquitin-protein ligase that mediates the ubiquitination of p53, leading to its degradation. MDM2 enhances tumour formation by inactivating the p53 tumour suppressor protein. The MDM2 gene also has many p53-independent functions. Alterations of MDM2 may occur through various mechanisms and contribute to the pathogenesis of many human tumours and some non-neoplastic diseases. Detection of MDM2 amplification is used in the clinical practice setting to help diagnose multiple tumour types, including lipomatous neoplasms, low-grade osteosarcomas and intimal sarcoma, among others. It is generally a marker of adverse prognosis, and MDM2-targeted therapies are currently in clinical trials. This article provides a concise overview of the MDM2 gene and discusses practical diagnostic applications pertaining to human tumour biology.

Targeting cyclin-dependent kinases in sarcoma treatment: Current perspectives and future directions

Effective treatment of advanced/metastatic bone and soft tissue sarcomas still represents an unmet medical need. Recent advances in targeted therapies have highlighted the potential of cyclin-dependent kinases (CDK) inhibitors in several cancer types, including sarcomas. CDKs are master regulators of the cell cycle; their dysregulation is listed among the "hallmarks of cancer" and sarcomas are no exception to the rule. In this review, we report both the molecular basis, and the potential therapeutic implications for the use of CDK inhibitors in sarcoma treatment. What is more, we describe and discuss the possibility and biological rationale for combination therapies with conventional treatments, target therapy and immunotherapy, highlighting potential avenues for future research to integrate CDK inhibition in sarcoma treatment.

Targeting the MDM2-p53 pathway in dedifferentiated liposarcoma

Dedifferentiated liposarcoma (DDLPS) is an aggressive adipogenic cancer with poor prognosis. DDLPS tumors are only modestly sensitive to chemotherapy and radiation, and there is a need for more effective therapies. Genetically, DDLPS is characterized by a low tumor mutational burden and frequent chromosomal structural abnormalities including amplification of the 12q13-15 chromosomal region and the MDM2 gene, which are defining features of DDLPS. The MDM2 protein is an E3 ubiquitin ligase that targets the tumor suppressor, p53, for proteasomal degradation. MDM2 amplification or overexpression in human malignancies is associated with cell-cycle progression and worse prognosis. The MDM2-p53 interaction has thus garnered interest as a therapeutic target for DDLPS and other malignancies. MDM2 binds p53 via a hydrophobic protein interaction that is easily accessible with synthetic analogues. Multiple agents have been developed, including Nutlins such as RG7112 and small molecular inhibitors including SAR405838 and HDM201. Preclinical in vitro and animal models have shown promising results with MDM2 inhibition, resulting in robust p53 reactivation and cancer cell death. However, multiple early-phase clinical trials have failed to show a benefit with MDM2 pathway inhibition for DDLPS. Mechanisms of resistance are being elucidated, and novel inhibitors and combination therapies are currently under investigation. This review provides an overview of these strategies for targeting MDM2 in DDLPS.

Amplification of CDK4 and MDM2: a detailed study of a high-risk neuroblastoma subgroup

In neuroblastoma, MYCN amplification and 11q-deletion are important, although incomplete, markers of high-risk disease. It is therefore relevant to characterize additional alterations that can function as prognostic and/or predictive markers. Using SNP-microarrays, a group of neuroblastoma patients showing amplification of one or multiple 12q loci was identified. Two loci containing CDK4 and MDM2 were commonly co-amplified, although amplification of either locus in the absence of the other was observed. Pharmacological inhibition of CDK4/6 with ribociclib or abemaciclib decreased proliferation in a broad set of neuroblastoma cell lines, including CDK4/MDM2-amplified, whereas MDM2 inhibition by Nutlin-3a was only effective in p53^wild-type cells. Combined CDK4/MDM2 targeting had an additive effect in p53^wild-type cell lines, while no or negative additive effect was observed in p53^mutated cells. Most 12q-amplified primary tumors were of abdominal origin, including those of intrarenal origin initially suspected of being Wilms' tumor. An atypical metastatic pattern was also observed with low degree of bone marrow involvement, favoring other sites such as the lungs. Here we present detailed biological data of an aggressive neuroblastoma subgroup hallmarked by 12q amplification and atypical clinical presentation for which our in vitro studies indicate that CDK4 and/or MDM2 inhibition also could be beneficial.

Noncanonical roles of p53 in cancer stemness and their implications in sarcomas

Impairment of the prominent tumor suppressor p53, well known for its canonical role as the "guardian of the genome", is found in almost half of human cancers. More recently, p53 has been suggested to be a crucial regulator of stemness, orchestrating the differentiation of embryonal and adult stem cells, suppressing reprogramming into induced pluripotent stem cells, or inhibiting cancer stemness (i.e., cancer stem cells, CSCs), which underlies the development of therapy-resistant tumors. This review addresses these noncanonical roles of p53 and their implications in sarcoma initiation and progression. Indeed, dysregulation of p53 family proteins is a common event in sarcomas and is associated with poor survival. Additionally, emerging studies have demonstrated that loss of wild-type p53 activity hinders the terminal differentiation of mesenchymal stem cells and leads to the development of aggressive sarcomas. This review summarizes recent findings on the roles of aberrant p53 in sarcoma development and stemness and further describes therapeutic approaches to restore normal p53 activity as a promising anti-CSC strategy to treat refractory sarcomas.

Co-Targeting of MDM2 and CDK4/6 with Siremadlin and Ribociclib for the Treatment of Patients with Well-Differentiated or Dedifferentiated Liposarcoma: Results From a Proof-of-Concept, Phase Ib Study

PURPOSE

Well-differentiated (WDLPS) and dedifferentiated (DDLPS) liposarcoma are characterized by co-amplification of the murine double minute-2 (MDM2) and cyclin-dependent kinase-4 (CDK4) oncogenes. Siremadlin, a p53-MDM2 inhibitor, was combined with ribociclib, a CDK4/6 inhibitor, in patients with locally advanced/metastatic WDLPS or DDLPS who had radiologically progressed on, or despite, prior systemic therapy.

METHODS

In this proof-of-concept, phase Ib, dose-escalation study, patients received siremadlin and ribociclib across different regimens until unacceptable toxicity, disease progression, and/or treatment discontinuation: Regimen A (4-week cycle: siremadlin once daily [QD] and ribociclib QD, [2 weeks on, 2 weeks off]); Regimen B (3-week cycle: siremadlin once every 3 weeks; ribociclib QD [2 weeks on, 1 week off]); Regimen C (4-week cycle: siremadlin once every 4 weeks; ribociclib QD [2 weeks on, 2 weeks off]). The primary objective was to determine the maximum tolerated dose and/or recommended dose for expansion (RDE) of siremadlin plus ribociclib in one or more regimens.

RESULTS

As of 16 October 2019 (last patient last visit), 74 patients had enrolled. Median duration of exposure was 13 (range, 1-174) weeks. Dose-limiting toxicities occurred in 10 patients, most of which were Grade 3/4 hematologic events. The RDE was siremadlin 120 mg every 3 weeks plus ribociclib 200 mg QD (Regimen B). Three patients achieved a partial response, and 38 achieved stable disease. One patient (Regimen C) died as a result of treatment-related hematotoxicity.

CONCLUSION

Siremadlin plus ribociclib demonstrated manageable toxicity and early signs of antitumor activity in patients with advanced WDLPS or DDLPS.

Expression of FRS2 in atypical lipomatous tumor/well-differentiated liposarcoma and dedifferentiated liposarcoma: an immunohistochemical analysis of 182 cases with genetic data

Background

The fibroblast growth factor receptor substrate 2 (FRS2) gene is located close to MDM2 and CDK4 within the 12q13-15 chromosomal region. FRS2 gene was recently found to be consistently amplified in atypical lipomatous tumor (ALT)/well-differentiated liposarcoma (WDL) and dedifferentiated liposarcoma (DDL), suggesting the detection of FRS2 amplification could be a diagnostic tool for ALT/WDL/DDLs. However, the expression of FRS2 protein and diagnostic value of FRS2 immunohistochemistry (IHC) has not been evaluated in a large cohort of ALT/WDL/DDLs.

Methods

A SNOMED search of hospital surgical pathology files from January 2007 to July 2020 identified 182 ALT/WDL/DDLs with available materials. FRS2 fluorescence in situ hybridization (FISH) and IHC were performed on 182 ALT/WDL/DDLs and 64 control samples. The expression of FRS2 was also compared with that of classic immunomarkers (MDM2 and CDK4) of this tumor entity.

Results

This study included 91 ALT/WDLs and 91 DDLs. The FISH results showed 172 of 182 (94.5%) cases were FRS2-amplified, and 10 cases were FRS2-nonamplified. Immunostaining results showed 171 (94.0%) ALT/WDL/DDLs were positive for FRS2 and 11 cases (6.0%) were FRS2-immunonegative. In 172 FRS2-amplified cases, 166 (96.5%) were FRS2-immunopositive, and 6 (3.5%) were negative. Among 10 FRS2-nonamplified ALT/WDL/DDL cases, 5 cases were FRS2-immunonegative, and 5 tumors displayed 1+ staining for this marker. In 64 control cases, none of them exhibited FRS2 amplification. Forty-seven (73.5%) control cases were negative for FRS2 immunostaining, while 17 cases (26.5%) were FRS2-immunopositive. Fifteen of these false positive samples (15/17, 88.2%) showed 1+ positivity and only 2 cases (2/17, 11.8%) displayed 2+ positivity. In ALT/WDL/DDLs, the sensitivity of FRS2 immunostaining was slightly lower than MDM2 (FRS2 vs. MDM2: 94.0% vs 100.0%) and CDK4 (FRS2 vs. CDK4: 94.0% vs 97.0%). However, the specificity of FRS2 (73.5%) was slightly higher than that of MDM2 (67.8%) and CDK4 (64.4%).

Conclusion

This study indicated that FRS2 IHC had relatively good consistency with FRS2 FISH, suggesting that FRS2 immunostaining could be utilized as an additional screening tool for the diagnosis of ALT/WDL/DDL. It must be emphasized that MDM2/CDK4/FRS2 especially MDM2 FISH remains the gold standard and the most recommended method to diagnose this entity.

Establishment and Characterization of NCC-DDLPS4-C1: A Novel Patient-Derived Cell Line of Dedifferentiated Liposarcoma

Dedifferentiated liposarcoma (DDLPS) is a highly malignant sarcoma characterized by the co-amplification of MDM2 and CDK4. Although systemic chemotherapy is recommended for unresectable or metastatic cases, DDLPS is insensitive to conventional chemotherapy, leading to an unfavorable prognosis. Therefore, novel treatment methods are urgently required. Patient-derived cell lines are essential in preclinical studies. Recently, large-scale screening studies using a number of cell lines have been actively conducted for the development of new therapeutic drugs. However, the DDLPS cell line cannot be obtained from public cell banks owing to its rarity, hindering screening studies. As such, novel DDLPS cell lines need to be established. Accordingly, this study aimed to establish a novel DDLPS cell line from surgical specimens. The cell line was named NCC-DDLPS4-C1. NCC-DDLPS4-C1 cells retained copy number alterations corresponding to the original tumors. Further, the cells demonstrated constant growth, spheroid formation, and equivalent invasiveness to MG63 osteosarcoma cells. We also conducted drug screening and integrated the results with those of the previously reported DDLPS cell lines. Consequently, we identified the histone deacetylase inhibitor romidepsin as a novel candidate drug. In conclusion, the NCC-DDLPS4-C1 cell line is a useful tool for the basic study of DDLPS.

The molecular landscape of well differentiated retroperitoneal liposarcoma

Well differentiated liposarcoma (WD-LPS) is a relatively rare tumour, with fewer than 50 cases occurring per year in the UK. These tumours are both chemotherapy- and radiotherapy-resistant and present a significant treatment challenge requiring radical surgery. Little is known of the molecular landscape of these tumours and no current targets for molecular therapy exist. We aimed to carry out a comprehensive molecular characterisation of WD-LPS via whole genome sequencing, RNA sequencing, and methylation array analysis. A recurrent mutation within exon 1 of FOXD4L3 was observed (chr9:70,918,189A>T; c.322A>T; p.Lys108Ter). Recurrent mutations were also observed in Wnt signalling, immunity, DNA repair, and hypoxia-associated genes. Recurrent amplification of HGMA2 was observed, although this was in fact part of a general amplification of the region around this gene. Recurrent gene fusions in HGMA2, SDHA, TSPAN31, and MDM2 were also observed as well as consistent rearrangements between chromosome 6 and chromosome 12. Our study has demonstrated a recurrent mutation within FOXD4L3, which shows evidence of interaction with the PAX pathway to promote tumourigenesis. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Lessons learnt from MDM2 fluorescence in-situ hybridisation analysis of 439 mature lipomatous lesions with an emphasis on atypical lipomatous tumour/well-differentiated liposarcoma lacking cytological atypia

AIMS

Amplification of the murine double minute-2 (MDM2) gene, which is usually detected with fluorescence in-situ hybridisation (FISH), is the key driving event for atypical lipomatous tumours (ALTs)/well-differentiated liposarcomas (WDLs). We sought to determine the concordance between the histopathological findings and MDM2 FISH in the diagnosis of ALT/WDL, and to identify the histological features of MDM2-amplified tumours lacking classic atypia.

METHODS AND RESULTS

We performed a retrospective analysis of all mature lipomatous lesions subjected to MDM2 FISH analysis at our institution. MDM2 FISH analysis was performed on 439 mature lipomatous lesions: 364 (82.9%) were negative and 75 (17%) were positive. In 17 of 75 (22.6%) ALTs/WDLs, cytological atypia was not identified on initial histological assessment, thus favouring lipoma. On review, these cases shared common histological features, consisting of a very low number of relatively small stromal cells within the tumour lobules, with mildly coarse chromatin and oval nuclei, admixed with unremarkable adipocytes in a tumour background devoid of fibroconnective septa, areas of fibrosis, or blood vessels. These cells matched the cells in which FISH showed MDM2 amplification. In contrast, 13 cases (3.5%) regarded as suspicious for ALT/WDL on the basis of histology lacked MDM2 amplification and were reclassified following the FISH findings.

CONCLUSIONS

We conclude that a subset of lipoma-like ALTs/WDLs are not associated with any of the features typically described in ALT/WDL. Our study also showed that tumours >100 mm are more likely to be ALT/WDL; however, a history of recurrence or concerning clinical/radiological features was not significantly associated with classification as ALT/WDL.

Clinical Application of Chromosome Microarray Analysis in the Diagnosis of Lipomatous Tumors

Well-differentiated liposarcoma/atypical lipomatous tumor (WDLS/ALT) and dedifferentiated liposarcoma (DDLS) have characteristic supernumerary ring and giant marker chromosomes involving the chromosomal region 12q13-15 which contains MDM2 (12q15), CDK4 (12q14.1), HMGA2 (12q14.3), YEATS4 (12q15), CPM (12q15), and FRS2 (12q15). Detecting MDM2 amplification by fluorescence in situ hybridization (FISH) is considered to be the gold standard for the diagnosis of WDLS/ALT and DDLS. In this study, formalin fixed paraffin embedded clinical specimens (16 liposarcomas and 19 benign lipomatous tumors) were used to detect MDM2 amplification and other chromosomal alterations in WDLS/ALT and DDLS by single nucleotide polymorphism-based chromosome microarray (CMA). All 16 liposarcomas showed MDM2 amplification with a MDM2/cep12 ratio from 2.4 to 8.4 by CMA. Ten (62.5%) of these cases had CDK4/cep12 ratio ≥2.0. All the cases without CDK4 amplification were from the thigh. The MDM2/cep12 ratio of all the benign lipomatous tumors (19/19) was within the normal limits. Twenty-one of the 35 benign lipomatous tumors and liposarcomas were also tested for MDM2 amplification by FISH. All the FISH results were consistent with the CMA results (100%). Along with MDM2 amplification, all 16 liposarcomas (100%) also showed amplification of YEATS4, CPM and FRS2. Only 11 of 16 (69%) cases showed HMGA2 amplification. In conclusion, this study demonstrated that CMA on routine formalin fixed paraffin embedded tissue is a sensitive and specific clinical test for detection of MDM2 gene amplification. Moreover, CMA allows simultaneous detection of genomic changes of interest including CDK4 and others, which provides enriched information for diagnosing lipomatous tumors.

Biology and Management of Dedifferentiated Liposarcoma: State of the Art and Perspectives

Dedifferentiated liposarcoma (DDL) is defined as the transition from well-differentiated liposarcoma (WDL)/atypical lipomatous tumor (ALT) to non-lipogenic sarcoma, which arises mostly in the retroperitoneum and deep soft tissue of proximal extremities. It is characterized by a supernumerary ring and giant marker chromosomes, both of which contain amplified sequences of 12q13-15 including murinedouble minute 2 (MDM2) and cyclin-dependent kinase 4 (CDK4) cell cycle oncogenes. Detection of MDM2 (and/or CDK4) amplification serves to distinguish DDL from other undifferentiated sarcomas. Recently, CTDSP1/2-DNM3OS fusion genes have been identified in a subset of DDL. However, the genetic events associated with dedifferentiation of WDL/ALT remain to be clarified. The standard treatment for localized DDL is surgery, with or without radiotherapy. In advanced disease, the standard first-line therapy is an anthracycline-based regimen, with either single-agent anthracycline or anthracycline in combination with the alkylating agent ifosfamide. Unfortunately, this regimen has not necessarily led to a satisfactory clinical outcome. Recent advances in the understanding of the pathogenesis of DDL may allow for the development of more-effective innovative therapeutic strategies. This review provides an overview of the current knowledge on the clinical presentation, pathogenesis, histopathology and treatment of DDL.

The utility of fluorescence in situ hybridization (FISH) in determining DNA damage-inducible transcript 3 (DDIT3) amplification in dedifferentiated liposarcomas - an important diagnostic pitfall

BACKGROUND AND OBJECTIVE

Dedifferentiated liposarcoma (DDLPS) is characterized by non-lipogenic sarcoma fields coexisting with adipocyte-rich well-differentiated areas. Amplification of the 12q13-15 region includes the MDM2 and DDIT3 genes. MDM2 amplification is considered a genetic hallmark of DDLPS, while DDIT3 is typically rearranged in myxoid liposarcoma. Recent studies showed that DDIT3 amplification is associated with myxoid liposarcoma-like (LPS-like) morphology in DDLPS. Our study aimed to evaluate the status of MDM2 and DDIT3 by FISH in DDLPS and correlate it with MLPS-like features.

MATERIAL AND METHODS

Six patients with MLPS-like morphology DDLPS were investigated pathologically, immunohistochemically, and genetically. The control groups of patients with classical DDLPS morphology and well-differentiated liposarcoma (WDLPS) were established and molecularly assessed as well. Fluorescence in situ hybridization (FISH) used in routine diagnostics was performed to determine the status of MDM2 and DDIT3 genes.

RESULTS

The patient's mean age was 64 (range from 43 to 85 years) with a 5:4 male to female ratio. Tumors were localized retroperitoneally (15) and extra-retroperitoneally (3). All cases demonstrated amplification of the 12q15 region containing MDM2 gene and co-amplification of the 5' DDIT3 FISH Probe representing DDIT3 telomeric tag. However, we did not find the relation of myxoid LPS-like morphology with DDIT3 amplification as previously reported.

CONCLUSIONS

The biopsy material from DDLPS with myxoid areas can be misclassified as myxoid liposarcoma. Indeed, according to the histological image, DDIT3 status may be evaluated first. In these cases, we show that the DDIT3 telomeric tag amplification assessed by FISH, is a common, nonspecific feature, which is also found in classical DDLPS and WDLPS. Therefore, we believe that co-amplification of DDIT3 and MDM2 may be considered a spectrum of the 12q13-15 region amplification due to the specification of FISH methodology.

Development of potent dimeric inhibitors of GAS41 YEATS domain

GAS41 is an emerging oncogene overexpressed and implicated in multiple cancers, including non-small cell lung cancer (NSCLC). GAS41 is a dimeric protein that contains the YEATS domain, which is involved in the recognition of lysine-acylated histones. Here, we report the development of GAS41 YEATS inhibitors by employing a fragment-based screening approach. These inhibitors bind to GAS41 YEATS domain in a channel constituting a recognition site for acylated lysine on histone proteins. To enhance inhibitory activity, we developed a dimeric analog with nanomolar activity that blocks interactions of GAS41 with acetylated histone H3. Our lead compound engages GAS41 in cells, blocks proliferation of NSCLC cells, and modulates expression of GAS41-dependent genes, validating on-target mechanism of action. This study demonstrates that disruption of GAS41 protein-protein interactions may represent an attractive approach to target lung cancer cells. This work exemplifies the use of bivalent inhibitors as a general strategy to block challenging protein-protein interactions.

Surgical Diagnosis and Treatment of Primary Retroperitoneal Liposarcoma

Background: Primary retroperitoneal liposarcoma (PRPLS) is the most common soft tissue sarcoma of the retroperitoneum with high recurrence rate and short overall survival (OS).

Methods: A retrospective review of 51 patients with PRPLS, treated between September 1, 2009 and November 30, 2020, was conducted to evaluate clinical outcomes of PRPLS resection. Patient demographics, histopathologic subtypes, overall survival (OS), progression-free survival (PFS), disease recurrence rate, and tumor stage were reviewed and analyzed. Univariate analysis was done to identify factors potentially affecting OS and PFS of PRPLS patients. Multivariate Cox proportional hazards analysis was used to evaluate the impact of various clinicopathological factors on OS and PFS of PRPLS patients.

Results: Fifty-one PRPLS patients (28 Males, 23 Females; mean age 56.25 years) were evaluated. There was no significant effect of age, gender, contiguous organ resection, degree of differentiation and tumor size on the OS and PFS of the patients. Univariate analysis showed that negative surgical margin and early tumor stage significantly correlated with OS and PFS (all P < 0.001). Multivariate analysis showed that tumor stage [hazard ratio (HR) = 1.177, P = 0.001] was an independent predictors of poor progression-free survival, and surgical margins [HR = 4.0674 P = 0.038] and tumor stage [HR = 1.167 P = 0.001] were identified as independent predictors of poor overall survival.

Conclusion: Negative surgical margin is a prognostic factor of OS, and can prolong the postoperative survival time of PRPLS patients. Tumor stage is a prognostic factor for OS and PFS, and can influence the survival of PRPLS patients. Earlier tumor stages of PRPLS are associated with significantly better outcomes.

A Rapid and Cost-Effective Gene Expression Assay for the Diagnosis of Well-Differentiated and Dedifferentiated Liposarcomas

Histologic examination neither reliably distinguishes benign lipomas from atypical lipomatous tumor/well-differentiated liposarcoma, nor dedifferentiated liposarcoma from other pleomorphic sarcomas, entities with different prognoses and management. Molecular confirmation of pathognomonic 12q13-15 amplifications leading to MDM2 overexpression is a diagnostic gold standard. Currently the most commonly used assay for this purpose is fluorescence in situ hybridization (FISH), but this is labor intensive. This study assessed whether newer NanoString-based technology could allow for more rapid and cost-efficient diagnosis of liposarcomas on standard formalin-fixed tissues through gene expression. Leveraging large-scale transcriptome data from The Cancer Genome Atlas, 20 genes were identified, most from the 12q13-15 amplicon, that distinguish dedifferentiated liposarcoma from other sarcomas and can be measured within a single NanoString assay. Using 21 cases of histologically ambiguous low-grade adipocytic tumors with available MDM2 amplification status, a machine learning-based analytical pipeline was built that assigns a given sample as negative or positive for liposarcoma based on quantitative gene expression. The effectiveness of the assay was validated on an independent set of 100 sarcoma samples (including 40 incident prospective cases), where histologic examination was considered insufficient for clinical diagnosis. The NanoString assay had a 93% technical success rate, and an accuracy of 97.8% versus an MDM2 amplification FISH gold standard. NanoString had a considerably faster turnaround time and was cheaper than FISH.

Prognostic significance of the MDM2/HMGA2 ratio and histological tumor grade in dedifferentiated liposarcoma

Dedifferentiated liposarcoma (DDLPS) is a relatively common soft tissue sarcoma that results from the progression of well-differentiated liposarcoma (WDLPS). This study aimed to investigate the progression process and to clarify the pathological and genetic factors related to poor prognosis in DDLPS. In 32 DDLPS cases and five WDLPS cases, genetic factors were analyzed by custom comparative genomic hybridization (CGH) array, which was designed to densely cover gene regions known to be frequently amplified in WD/DDLPS. The analyses comparing primary and metastatic lesions and those comparing histologically different areas in the same tumor revealed intra-tumoral genetic heterogeneity and progression. According to a prognostic analysis comparing the good-prognosis and the poor-prognosis groups, we selected MDM2 and HMGA2 as candidate genes associated with poor and good prognosis, respectively. The ratios of the amplification or gain levels of MDM2 and HMGA2 expressed in log ratios (log[MDM2/HMGA2] = log[MDM2]-log[HMGA2]) were significantly associated with prognosis. An amplification or gain level of MDM2 that was more than twice that of HMGA2 (MDM2/HMGA2 > 2, log[MDM2/HMGA2] > 1) was strongly related to poor OS (P < .001) and poor distant metastasis-free survival (DMFS) (P < .001). In the pathological analysis of 44 cases of DDLPS, histological tumor grade, cellular atypia, and MDM2 immunoreactivity were related to overall survival (OS), while HMGA2 immunoreactivity tended to be associated with OS. Cellular atypia was also associated with DMFS. In conclusion, histological grade and MDM2 expression were determined to be prognostically important, and the MDM2/HMGA2 amplification or gain ratio was found to have significant prognostic value by the custom CGH array analysis.

Establishment and characterization of NCC-DDLPS1-C1: a novel patient-derived cell line of dedifferentiated liposarcoma

Dedifferentiated liposarcoma (DDLPS) is one of the four subtypes of liposarcomas; it is characterized by the amplification of the 12q13-15 region, which includes MDM2 and CDK4 genes. DDLPS has an extremely high local recurrence rate and is refractory to chemotherapy and radiation, which leads to poor prognosis. Therefore, a novel therapeutic strategy should be urgently established for improving the prognosis of DDLPS. Although patient-derived cell lines are important tools for basic research, there are no DDLPS cell lines available from public cell banks. Here, we report the establishment of a novel DDLPS cell line. Using the surgically resected tumor tissue from a patient with DDLPS, we established a cell line and named it NCC-DDLPS1-C1. The NCC-DDLPS1-C1 cells contained 12q13-15, 1p32, and 1q23 amplicons and highly expressed MDM2 and CDK4 proteins. NCC-DDLPS-C1 cells exhibited constant growth, spheroid formation, aggressive invasion, and tumorigenesis in mice. By screening a drug library, we identified that the proteasome inhibitor, bortezomib, had inhibitory effects on the proliferation of NCC-DDLPS1-C1 cells. We concluded that the NCC-DDLPS1-C1 cell line may serve as a useful tool for basic and pre-clinical studies of DDLPS.

The DYRK Family of Kinases in Cancer: Molecular Functions and Therapeutic Opportunities

DYRK (dual-specificity tyrosine-regulated kinases) are an evolutionary conserved family of protein kinases with members from yeast to humans. In humans, DYRKs are pleiotropic factors that phosphorylate a broad set of proteins involved in many different cellular processes. These include factors that have been associated with all the hallmarks of cancer, from genomic instability to increased proliferation and resistance, programmed cell death, or signaling pathways whose dysfunction is relevant to tumor onset and progression. In accordance with an involvement of DYRK kinases in the regulation of tumorigenic processes, an increasing number of research studies have been published in recent years showing either alterations of DYRK gene expression in tumor samples and/or providing evidence of DYRK-dependent mechanisms that contribute to tumor initiation and/or progression. In the present article, we will review the current understanding of the role of DYRK family members in cancer initiation and progression, providing an overview of the small molecules that act as DYRK inhibitors and discussing the clinical implications and therapeutic opportunities currently available.

A review of retroperitoneal liposarcoma genomics

Retroperitoneal liposarcomas are rare tumours that carry a poorer prognosis than their extremity counterparts. Within their subtypes - well differentiated (WDL), dedifferentiated (DDL), myxoid (MLS) and pleomorphic (PLS) - they exhibit a diverse genomic landscape. With recent advances in next generation sequencing, the number of studies exploring this have greatly increased. The recent literature has deepened our understanding of the hallmark MDM2/CDK4 amplification in WDL/DDL and addressed concerns about toxicity and resistance when targeting this. The FUS-DDIT3 fusion gene remains the primary focus of interest in MLS with additional potential targets described. Whole genome sequencing has driven identification of novel genes and pathways implicated in WDL/DDL outside of the classic 12q13-15 amplicon. Due to their rarity; anatomical location and histologic subtype are infrequently mentioned when reporting the results of these studies. Reports can include non-adipogenic or extremity tumours, making it difficult to draw specific retroperitoneal conclusions. This narrative review aims to provide a summary of retroperitoneal liposarcoma genomics and the implications for therapeutic targeting.

Dedifferentiated Liposarcoma: Systemic Therapy Options

OPINION STATEMENT

Over the last several years, the systemic treatment landscape for dedifferentiated liposarcoma (DDLPS) has notably expanded. Historically, systemic therapy options have been limited to cytotoxic chemotherapy agents, including doxorubicin, ifosfamide, gemcitabine, and docetaxel, that were shown to have efficacy in unselected populations of patients with soft tissue sarcomas. More recently, however, there have been phase II and III trials establishing clinical benefit of the cytotoxic agents trabectedin and eribulin along with the tyrosine kinase inhibitor pazopanib in patients with advanced liposarcoma and DDLPS. Additionally, there are several investigational targeted therapies that have incorporated advances in the understanding of DDLPS disease biology, exploiting the fact that nearly all such tumors include highly amplified expression of MDM2 and CDK4. Recent clinical trials have supported the benefit of the CDK4 inhibitor abemaciclib and the nuclear export inhibitor selinexor and support continued development of anti-MDM2 therapies, with particular attention to the bone marrow toxicity and resultant thrombocytopenia that has thus far limited their use. In contrast, the checkpoint inhibitors pembrolizumab and nivolumab remain of questionable benefit, although these immunotherapy drugs may have a role when combined with other therapeutic agents. Ongoing phase III trials will clarify the role of these novel agents. Future directions include directly comparing current standard-of-care options and newer therapies, developing synergistic combinations of novel agents, and evaluating their role in patients with localized DDLPS.

Liposarcoma: Advances in Cellular and Molecular Genetics Alterations and Corresponding Clinical Treatment

Liposarcoma is a malignant tumor of mesenchymal origin with significant tissue diversity. It is composed of adipocytes with different degrees of differentiation and different degrees of heteromorphosis. It is not sensitive to traditional radiotherapy and chemotherapy and has a poor prognosis. In recent years, with the rapid development of basic immunology, molecular genetics and tumor molecular biology, the histological classification of liposarcoma has become increasingly clear. More and more new methods and technologies, such as gene expression profile analysis, the whole genome sequencing, miRNA expression profile analysis and RNA sequencing, have been successfully applied to liposarcoma, bringing about a deeper understanding of gene expression changes and molecular pathogenic mechanisms in the occurrence and development of liposarcoma. This study reviews the present research status and progress of cellular and molecular alterations of liposarcoma and corresponding clinical treatment progress.

Integrated exome and RNA sequencing of dedifferentiated liposarcoma

The genomic characteristics of dedifferentiated liposarcoma (DDLPS) that are associated with clinical features remain to be identified. Here, we conduct integrated whole exome and RNA sequencing analysis in 115 DDLPS tumors and perform comparative genomic analysis of well-differentiated and dedifferentiated components from eight DDLPS samples. Several somatic copy-number alterations (SCNAs), including the gain of 12q15, are identified as frequent genomic alterations. CTDSP1/2-DNM3OS fusion genes are identified in a subset of DDLPS tumors. Based on the association of SCNAs with clinical features, the DDLPS tumors are clustered into three groups. This clustering can predict the clinical outcome independently. The comparative analysis between well-differentiated and dedifferentiated components identify two categories of genomic alterations: shared alterations, associated with tumorigenesis, and dedifferentiated-specific alterations, associated with malignant transformation. This large-scale genomic analysis reveals the mechanisms underlying the development and progression of DDLPS and provides insights that could contribute to the refinement of DDLPS management.

Understanding the genomic features of dedifferentiated liposarcoma (DDLPS) is likely to uncover new options for management. Here, the authors reveal three prognostic groups, and highlight molecular markers associated with malignant transformation.

RETROPERITONEAL NON-ORGAN LIPOSARCOMAS: THE MODERN CONCEPT

Objective:to conduct a systematic literature review of the published studies on retroperitoneal non-organ liposarcomas.

Material and Methods.A literature search was performed using Pubmed, Elibrary, COSMIC databases. The data of retrospective and prospective clinical trials were analyzed. Results. The article reviews contemporary data on epidemiology, classification, clinicalmorphological and molecular-genetic characteristics, as well as diagnosis and treatment of retroperitoneal non-organ liposarcomas. Conclusion. Retroperitoneal sarcomas account for about 13 % of all types of soft tissue sarcomas. Liposarcoma is the most common retroperitoneal mesenchymal tumor. Diagnosis and treatment of non-organ retroperitoneal liposarcoma remain challenging due to poor long-term treatment outcomes. As experience is gained with the diagnosis and treatment of retroperitoneal nonorganic liposarcomas, changes occur in the system of understanding the problem that determines the strategy for providing medical care in this category of patients. The article presents modern concept of retroperitoneal non-organ liposarcomas.

[Tumors with predominantly adipocytic morphology]

More than 20% of soft-tissue tumors belong to the group of adipocytic neoplasms. Difficulties may occur in the differential diagnosis of lipomas versus atypical lipomatous tumors/well-differentiated liposarcomas, in the distinction of dedifferentiated liposarcomas from other soft-tissue sarcoma entities and in the detailed subtyping of liposarcomas. Especially in biopsies, the correct diagnosis and grading may be hampered due to limited tissue. Because of the ever-increasing molecular-pathological knowledge of soft-tissue tumors and the rising distribution of molecular diagnostic assays in institutes of pathology, differential diagnosis has been facilitated, as more than 90% of adipocytic tumors carry more or less specific genomic alterations. In the following, the most important subtypes of adipocytic tumors are described morphologically and genomically.

Using biology to guide the treatment of sarcomas and aggressive connective-tissue tumours

Sarcomas are a heterogeneous group of malignancies that arise from cells of a mesenchymal origin. Surgery forms the mainstay of the treatment of most patients with localized sarcoma and might be followed or preceded by chemotherapy and/or radiotherapy. In the metastatic setting, systemic treatments tend to improve survival and control symptoms. However, the adverse events and sometimes disappointing outcomes associated with these empirical approaches to treatment indicate a need for new approaches. The advent of next-generation sequencing (NGS) has enabled more targeted treatment of many malignancies based on the presence of specific alterations. NGS analyses of sarcomas have revealed the presence of many alterations that can be targeted using therapies that are already used in patients with other forms of cancer. In this Review, we describe the genomic alterations considered to define specific nosological subgroups of sarcoma and whose contribution to oncogenesis provides a biological rationale for the use of a specific targeted therapy. We also report several less successful examples that should guide researchers and clinicians to better define the extent to which the identification of driver molecular alterations should influence the development of novel treatments.

Well-differentiated liposarcoma and dedifferentiated liposarcoma: An updated review

Well-differentiated liposarcoma (WDL)/atypical lipomatous tumor and dedifferentiated liposarcoma (DDL) together comprise the largest subgroup of liposarcomas, and constitute a histologic and behavioral spectrum of one disease. WDL and DDL typically occur in middle-aged to older adults, particularly within the retroperitoneum or extremities. WDL closely resembles mature adipose tissue, but typically shows fibrous septation with variable nuclear atypia and enlargement. WDL does not metastasize, but can dedifferentiate to DDL, which is associated with more aggressive clinical behavior, with a greater propensity for local recurrence and the capacity for metastasis. Although distant metastasis is rarer in DDL compared with other pleomorphic sarcomas, behavior is related to location, with a significantly worse outcome in retroperitoneal tumors. DDL typically has the appearance of undifferentiated pleomorphic or spindle cell sarcoma, and is usually a non-lipogenic sarcoma that is adjacent to WDL, occurs as a recurrence of WDL or which can arise de novo. WDL and DDL share similar background genetic aberrations; both are associated with high-level amplifications in the chromosomal 12q13-15 region, which includes the CDK4 and MDM2 cell cycle oncogenes. In addition, DDL harbor further genetic changes, particularly 6q23 and 1p32 coamplifications. While surgical excision remains the treatment mainstay with limited medical options for patients with aggressive recurrent disease or metastases, novel targeted therapies towards the gene products of chromosome 12 are being evaluated. This review summarizes the pathology of WDL and DDL, discussing morphology, immunohistochemistry, genetics and the differential diagnosis.

Molecular updates in adipocytic neoplasms✰

Adipocytic neoplasms include a diversity of both benign tumors (lipomas) and malignancies (liposarcomas), and each tumor type is characterized by its own unique molecular alterations driving tumorigenesis. Work over the past 30 years has established the diagnostic utility of several of these characteristic molecular alterations (e.g. MDM2 amplification in well- and dedifferentiated liposarcoma, FUS/EWSR1-DDIT3 gene fusions in myxoid liposarcoma, RB1 loss in spindle cell/pleomorphic lipoma). More recent studies have focused on additional molecular alterations which may have therapeutic or prognostic impact. This review will summarize several of the important molecular findings in adipocytic tumors that have been described over the past 10 years.

A contemporary review of myxoid adipocytic tumors

Myxoid adipocytic tumors encompass a broad heterogeneous group of benign and malignant adipocytic tumors, which are typically myxoid (e.g. myxoid liposarcoma, lipoblastoma and lipoblastoma-like tumor of the vulva) or may occasionally appear predominantly myxoid (e.g. pleomorphic liposarcoma, atypical lipomatous tumor, dedifferentiated liposarcoma, chondroid lipoma, spindle cell/pleomorphic lipoma, atypical spindle cell lipomatous tumor and atypical pleomorphic lipomatous tumor). There have been significant advances in recent years in classification and understanding the pathogenesis of adipocytic tumors, based on the correlation of histologic, immunohistochemical, and cytogenetic/molecular findings. Despite these advances, the morphologic diagnosis and accurate classification of a myxoid adipocytic tumor can be challenging due to major morphologic overlap between myxoid adipocytic and non-adipocytic tumors. This article will provide a review on the currently known morphological, immunohistochemical and molecular features of myxoid adipocytic tumors and their differential diagnosis.

Co-expression of MDM2 and CDK4 in transformed human mesenchymal stem cells causes high-grade sarcoma with a dedifferentiated liposarcoma-like morphology

Amplification and overexpression of MDM2 and CDK4 are well-known diagnostic criteria for well-differentiated liposarcoma (WDLPS)/dedifferentiated liposarcoma (DDLPS). Although it was reported that the depletion of MDM2 or CDK4 decreased proliferation in DDLPS cell lines, whether MDM2 and CDK4 induce WDLPS/DDLPS tumorigenesis remains unclear. We examined whether MDM2 and/or CDK4 cause WDLPS/DDLPS, using two types of transformed human bone marrow stem cells (BMSCs), 2H and 5H, with five oncogenic hits (overexpression of hTERT, TP53 degradation, RB inactivation, c-MYC stabilization, and overexpression of HRAS^v12). In vitro functional experiments revealed that the co-overexpression of MDM2 and CDK4 plays a key role in tumorigenesis by increasing cell growth and migration and inhibiting adipogenic differentiation potency when compared with the sole expression of MDM2 or CDK4. Using mouse xenograft models, we found that the co-overexpression of MDM2 and CDK4 in 5H cells with five additional oncogenic mutations can cause proliferative sarcoma with a DDLPS-like morphology in vivo. Our results suggest that the co-overexpression of MDM2 and CDK4, along with multiple genetic factors, increases the tendency for high-grade sarcoma with a DDLPS-like morphology in transformed human BMSCs by accelerating their growth and migration and blocking their adipogenic potential.

Clinical Utility of In Situ Hybridization Assays in Head and Neck Neoplasms

Head and neck pathology present a unique set of challenges including the morphological diversity of the neoplasms and presentation of metastases of unknown primary origin. The detection of human papillomavirus and Epstein-Barr virus associated with squamous cell carcinoma and newer entities like HPV-related carcinoma with adenoid cystic like features have critical prognostic and management implications. In salivary gland neoplasms, differential diagnoses can be broad and include non-neoplastic conditions as well as benign and malignant neoplasms. The detection of specific gene rearrangements can be immensely helpful in reaching the diagnosis in pleomorphic adenoma, mucoepidermoid carcinoma, secretory carcinoma, hyalinizing clear cell carcinoma and adenoid cystic carcinoma. Furthermore, molecular techniques are essential in diagnosis of small round blue cell neoplasms and spindle cell neoplasms including Ewing sarcoma, rhabdomyosarcoma, synovial sarcoma, biphenotypic sinonasal sarcoma, dermatofibrosarcoma protuberans, nodular fasciitis and inflammatory myofibroblastic tumor. The detection of genetic rearrangements is also important in lymphomas particularly in identifying 'double-hit' and 'triple-hit' lymphomas in diffuse large B cell lymphoma. This article reviews the use of in situ hybridization in the diagnosis of these neoplasms.

Solitary fibrous tumor

Solitary fibrous tumor (SFT) is a rare tumor of mesenchymal origin that account for less than 2% of all soft tissue masses. Initially identified in the pleura, SFT has been identified in multiple anatomic locations and can arise anywhere in the body. The varying histologic features along with non-specific means of identification have led SFT to be associated with several different names. Over the last several decades, sustained advances through research and technology have led to more reliable methods for differentiating this distinct soft tissue tumor. Advances specifically in immunohistochemistry and molecular diagnostics have identified CD34 as the most consistent marker in SFT, however even this lacks specificity to conclusively narrow down the broad differential for exact identification. More recently the discovery of the NAB2-STAT6 fusion gene has led to more precise diagnosis of SFT. Like many other soft tissue tumors, surgical management is the mainstay of treatment for SFT with emphasis on obtaining tumor-negative margins. Radiation therapy and chemotherapy regimens have not demonstrated global effectiveness, and thus no standardized treatments have been identified. Given the rarity of SFT and current supportive evidence for therapies, management should be focused on tumor extirpation. Nonetheless, individualized therapy, determined within a multidisciplinary setting should be considered.

Mesenchymal Neoplasms of the Genitourinary System: A Selected Review with Recent Advances in Clinical, Diagnostic, and Molecular Findings

Mesenchymal neoplasms of the genitourinary (GU) tract often pose considerable diagnostic challenges due to their wide morphologic spectrum, relative rarity, and unexpected incidence at GU sites. Soft tissue tumors arise throughout the GU tract, whether from adventitia surrounding or connective tissues within the kidneys, urinary bladder, and male and female genital organs. This selected article focuses on a subset of these lesions, ranging from benign to malignant and encompassing a range of patterns of mesenchymal differentiation, where recent scholarship has lent greater insight into their clinical, molecular, or diagnostic features.

Diagnostic Immunohistochemistry for Soft Tissue and Bone Tumors: An Update

Although some soft tissue and bone tumors can be identified based on histologic features alone, immunohistochemistry plays a critical diagnostic role for most mesenchymal tumor types. The discovery of recurrent genomic alterations in many benign and malignant mesenchymal neoplasms has added important biologic insights and expanded the spectrum of some diagnostic subgroups. Some tumors are defined by unique genomic alterations, whereas others share abnormalities that are not tumor-specific and can be observed in a sometimes broad range of biologically unrelated neoplasms. We herein focus on novel immunohistochemical markers, based on molecular genetic alterations, which are particularly useful in the diagnostic workup of selected groups of soft tissue and bone tumors, including recently described entities, specifically round cell sarcomas (Ewing sarcoma, CIC-rearranged sarcoma, and BCOR-rearranged sarcoma), vascular tumors (epithelioid hemangioma, epithelioid hemangioendothelioma, and pseudomyogenic hemangioendothelioma), SMARCB1-deficient neoplasms, adipocytic tumors (spindle cell/pleomorphic lipoma, atypical spindle cell lipomatous tumor, and conventional atypical lipomatous tumor), giant cell-rich bone tumors (giant cell tumor of bone and chondroblastoma), and biphenotypic sinonasal sarcoma. Given the complex nature of sarcoma classification, and the rarity of many mesenchymal tumor types, careful integration of clinical presentation, imaging features, histology, immunophenotype, and cytogenetic/molecular alterations is crucial for accurate diagnosis of soft tissue and bone tumors.

Integrated genetic and epigenetic analysis of myxofibrosarcoma

Myxofibrosarcoma (MFS) is a common adult soft tissue sarcoma characterized by an infiltrative growth pattern and a high local recurrence rate. Here we report the genetic and epigenetic landscape of MFS based on the results of whole-exome sequencing (N = 41), RNA sequencing (N = 29), and methylation analysis (N = 41), using 41 MFSs as a discovery set, and subsequent targeted sequencing of 140 genes in the entire cohort of 99 MFSs and 17 MFSs' data from TCGA. Fourteen driver genes are identified, including potentially actionable therapeutic targets seen in 37% of cases. There are frequent alterations in p53 signaling (51%) and cell cycle checkpoint genes (43%). Other conceivably actionable driver genes including ATRX, JAK1, NF1, NTRK1, and novel oncogenic BRAF fusion gene are identified. Methylation patterns cluster into three subtypes associated with unique combinations of driver mutations, clinical outcomes, and immune cell compositions. Our results provide a valuable genomic resource to enable the design of precision medicine for MFS.

Myxofibrosarcoma occurs in adults and is associated with high local relapse. Here, based on exome/transcriptome sequencing and DNA methylation analysis, the authors identify driver genes and methylation clusters associated with unique combinations of mutations, outcomes, and immune cell compositions.