Multiregion exome sequencing of ovarian immature teratomas reveals 2N near-diploid genomes, paucity of somatic mutations, and extensive allelic imbalances shared across mature, immature, and disseminated components

Characterization of testicular embryonic-type neuroectodermal tumor and embryonic-type neuroectodermal tissue admixed with mature neuro-glial tissue using a broad immunohistochemical panel

Embryonic-type neuroectodermal tumor (ENT) is a somatic-type malignancy characterized by overgrowth of embryonic-type neuroectodermal tissue (EtNT). In germ cell tumors, EtNT is frequently intermingled with other components that may exhibit significant morphologic overlap [mature neuro-glial tissue (MNGT), nephroblastomatous tissues, and primitive endodermal-type glands]. Therefore, the quantification of EtNT (crucial for the diagnosis of ENT) can be challenging. In this study, we investigated the immunohistochemical profile of ENT, EtNT, and MNGT using a broad immunohistochemical panel. We found that SOX2 was the most sensitive marker for EtNT (100%), but it also stained MNGT (28.6%). GFAP and S100 were relatively sensitive (71.4%) and highly specific (GFAP 100%, S100 85.8%) for MNGT, whereas synaptophysin stained both. Combining our results with those of previous studies, we propose that a combination of SOX11, SOX2, GFAP, S100, AFP, villin, CDX2, PAX8, and nuclear WT1 may help to identify and quantify EtNT in germ cell tumors.

A rare germline BMP15 missense mutation causes hereditary ovarian immature teratoma in human

Ovarian immature teratomas (OITs) are malignant tumors originating from the ovarian germ cells that mainly occur during the first 30 y of a female's life. Early age of onset strongly suggests the presence of susceptibility gene mutations for the disease yet to be discovered. Whole exon sequencing was used to screen pathogenic mutations from pedigrees with OITs. A rare missense germline mutation (C262T) in the first exon of the BMP15 gene was identified. In silico calculation suggested that the mutation could impair the formation of mature peptides. In vitro experiments on cell lines confirmed that the mutation caused an 84.7% reduction in the secretion of mature BMP15. Clinical samples from OIT patients also showed a similar pattern of decrease in the BMP15 expression. In the transgenic mouse model, the spontaneous parthenogenetic activation significantly increased in oocytes carrying the T allele. Remarkably, a mouse carrying the T allele developed the phenotype of OIT. Oocyte-specific RNA sequencing revealed that abnormal activation of the H-Ras/MAPK pathway might contribute to the development of OIT. BMP15 was identified as a pathogenic gene for OIT which improved our understanding of the etiology of OIT and provided a potential biomarker for genetic screening of this disorder.

Adolescent and Young Adult Germ Cell Tumors: Epidemiology, Genomics, Treatment, and Survivorship

Innovations in the care of adolescent and young adult (AYA) germ cell tumors (GCTs) are needed for one of the most common AYA cancers for which treatment has not significantly changed for several decades. Testicular GCTs (TGCTs) are the most common cancers in 15- to 39-year-old men, and ovarian GCTs (OvGCTs) are the leading gynecologic malignancies in women younger than 25 years. Excellent outcomes, even in widely metastatic disease using cisplatin-based chemotherapy, can be achieved since Einhorn and Donohue's landmark 1977 study in TGCT. However, as the severity of accompanying late effects (ototoxicity, neurotoxicity, cardiovascular disease, second malignant neoplasms, nephrotoxicity, and others) has emerged, efforts to deintensity treatment and find alternatives to cisplatin have taken on new urgency. Current innovations include the collaborative design of clinical trials that accrue GCTs across all ages and both sexes, including adolescents (previously on pediatric trials), and OvGCT (previously on gynecologic-only trials). Joint trials accrue larger sample sizes at a faster rate and therefore evaluate new approaches more rapidly. These joint trials also allow for biospecimen collection to further probe GCT etiology and underlying mechanisms of tumor growth, thus providing new therapeutic options. This AYA approach has been fostered by The Malignant Germ Cell International Consortium, which includes over 115 GCT disease experts from pediatric, gynecologic, and genitourinary oncologies in 16 countries. Trials in development incorporate, to our knowledge, for the first time, molecular risk stratification and precision oncology approaches on the basis of specific GCT biology. This collaborative AYA approach pioneering successfully in GCT could serve as a model for impactful research for other AYA cancer types.

Molecular features for timely cancer diagnosis and treatment - tumors of the ovary, fallopian tube and endometrium

Gynecologic pathology has moved, within only a few years, from being a diagnostic area devoid of molecular testing into a diagnostic discipline in which such analyses are becoming routine. The direct relevance of molecular characterization to the choice of treatment of patients with carcinomas originating in both the uterus and adnexae makes it likely that such testing will only expand along with our understanding of the molecular make-up of these tumors. As a consequence, gynecologic pathologists have become an integral part of patient management, rather than lab personnel providing external services.In parallel, molecular testing is expanding as a tool for diagnosing rare tumors affecting these organs, including soft tissue tumors, sex cord-stromal tumors and germ cell tumors, as well as other rare entities. Increased knowledge in this area bears directly on the ability to diagnose these tumors in a reproducible manner, as well as recognize and consult on genetic diseases. Hopefully, despite the inherent difficulty in studying rare cancers, it will also translate into new therapeutic options for the malignant ones among these rare cancers.

An Overview of Advances in Rare Cancer Diagnosis and Treatment

Cancer stands as the leading global cause of mortality, with rare cancer comprising 230 distinct subtypes characterized by infrequent incidence. Despite the inherent challenges in addressing the diagnosis and treatment of rare cancers due to their low occurrence rates, several biomedical breakthroughs have led to significant advancement in both areas. This review provides a comprehensive overview of state-of-the-art diagnostic techniques that encompass new-generation sequencing and multi-omics, coupled with the integration of artificial intelligence and machine learning, that have revolutionized rare cancer diagnosis. In addition, this review highlights the latest innovations in rare cancer therapeutic options, comprising immunotherapy, targeted therapy, transplantation, and drug combination therapy, that have undergone clinical trials and significantly contribute to the tumor remission and overall survival of rare cancer patients. In this review, we summarize recent breakthroughs and insights in the understanding of rare cancer pathophysiology, diagnosis, and therapeutic modalities, as well as the challenges faced in the development of rare cancer diagnosis data interpretation and drug development.

Ovarian Immature Teratoma With Nodal Gliomatosis: A Case Report and Literature Review

Gliomatosis involving lymph nodes (nodal gliomatosis) is rarely encountered in association with an ovarian teratoma, with 12 cases previously reported. We report this rare occurrence in a 23-yr-old female with an ovarian immature teratoma. The ovary contained a grade 3 immature teratoma, with immature neuroepithelium. A subcapsular liver mass contained metastatic immature teratoma with neuroepithelium. The omentum and peritoneum contained mature glial tissue, consistent with gliomatosis peritonei with no evidence of immature elements. One pelvic lymph node contained multiple nodules of mature glial tissue, diffusely positive for glial fibrillary acidic protein, in keeping with nodal gliomatosis. In reporting this case, we review prior reports of nodal gliomatosis.

Benign and Malignant Ovarian Teratomas: Multimodality Imaging Findings With Histopathologic Correlation

ABSTRACT

The purpose of this article is to provide a comprehensive review of the imaging findings along with histopathologic correlation of mature (benign) teratomas and malignant ovarian teratomas, which include both immature teratomas and malignant degeneration of mature teratomas. The radiologist's ability to provide an accurate diagnosis plays an essential role in guiding the interdisciplinary care of patients with malignant teratomas and improving their outcomes.

Overcoming Barriers to Tumor Genomic Profiling through Direct-to-Patient Outreach

PURPOSE

To overcome barriers to genomic testing for patients with rare cancers, we initiated a program to offer free clinical tumor genomic testing worldwide to patients with select rare cancer subtypes.

EXPERIMENTAL DESIGN

Patients were recruited through social media outreach and engagement with disease-specific advocacy groups, with a focus on patients with histiocytosis, germ cell tumors (GCT), and pediatric cancers. Tumors were analyzed using the MSK-IMPACT next-generation sequencing assay with the return of results to patients and their local physicians. Whole-exome recapture was performed for female patients with GCTs to define the genomic landscape of this rare cancer subtype.

RESULTS

A total of 333 patients were enrolled, and tumor tissue was received for 288 (86.4%), with 250 (86.8%) having tumor DNA of sufficient quality for MSK-IMPACT testing. Eighteen patients with histiocytosis have received genomically guided therapy to date, of whom 17 (94%) have had clinical benefit with a mean treatment duration of 21.7 months (range, 6-40+). Whole-exome sequencing of ovarian GCTs identified a subset with haploid genotypes, a phenotype rarely observed in other cancer types. Actionable genomic alterations were rare in ovarian GCT (28%); however, 2 patients with ovarian GCTs with squamous transformation had high tumor mutational burden, one of whom had a complete response to pembrolizumab.

CONCLUSIONS

Direct-to-patient outreach can facilitate the assembly of cohorts of rare cancers of sufficient size to define their genomic landscape. By profiling tumors in a clinical laboratory, results could be reported to patients and their local physicians to guide treatment. See related commentary by Desai and Subbiah, p. 2339.

Molecular Biology of Pediatric and Adult Ovarian Germ Cell Tumors: A Review

Ovarian germ cell tumors (OGCTs) are rare in adults; indeed, they occur predominantly in children, adolescents, and young adults, and they account for approximately 11% of cancer diagnoses in these groups. Because OGCTs are rare tumors, our current understanding of them is sparse; this is because few studies have investigated the molecular basis of pediatric and adult cancers. Here, we review the etiopathogenesis of OGCTs in children and adults, and we address the molecular landscape of these tumors, including integrated genomic analysis, microRNAs, DNA methylation, the molecular implications of treatment resistance, and the development of in vitro and in vivo models. An elucidation of potential molecular alterations may provide a novel field for understanding the pathogenesis, tumorigenesis, diagnostic markers, and genetic peculiarity of the rarity and complexity of OGCTs.

Immature Teratoma: Diagnosis and Management-A Review of the Literature

An immature teratoma is a germinal malignant tumor composed of three germ cell layers, occurring more frequently in young women. It is the second most frequent among the malignant germinal tumors after dysgerminoma, and it is the only neoplasm with germ cells that are histologically graded. Even if we do not have a consensus regarding its therapeutical management, it has a good prognosis, with an excellent overall survival rate and good fertility preservation. More studies are needed regarding the necessity of adjuvant chemotherapy in pediatric oncology, and because of chemotherapy's long-term adverse effects, surveillance or a targeted treatment is preferred, but the main therapy is fertility-sparing surgery. Special attention should be given to the genetic mapping of the histological pieces for patient risk stratification due to its value in prognosis and future treatment.

Mature and immature ovarian teratomas share methylation profiles of imprinted genes: a MS-MLPA analysis

Immature teratomas are a subset of ovarian teratomas, and the pathogenic relationship between mature and immature ovarian teratomas is unclear. Mature ovarian teratomas are parthenogenetic tumors that arise from a single oocyte/ovum, whereas the origin of immature ovarian teratomas has not been extensively investigated. Since parthenogenetic tumors contain only maternal genomes, genome imprinting in these tumors usually follows a maternal pattern. DNA methylation is among the most important mechanisms of genome imprinting. Therefore, we analyzed the methylation profile of imprinted genes by performing methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) of 25 imprinting control regions (ICRs) in 10 imprinted genes/gene clusters from formalin-fixed, paraffin-embedded samples obtained from 4 immature ovarian teratomas, 8 mature ovarian teratomas, and 4 ovarian yolk sac tumors (YSTs). Both the immature and mature components showed similar methylation levels in each ICR in immature teratomas. Overall, immature ovarian teratomas showed maternal methylation patterns of imprinted genes in concordance with their parthenogenetic origin. However, they also showed aberrant methylation levels in a few imprinted genes, suggesting that genome imprinting in immature teratomas may partially differ from that in mature teratomas. Microscopic foci of YST were seen in one immature teratoma; the YST component also showed a maternal methylation pattern, unlike the pure YSTs that showed irregular patterns. Thus, teratoma-associated YST and pure YST may have different pathogenic mechanisms.

Characterization of immature ovarian teratomas through single-cell transcriptome

Introduction

Immature ovarian teratomas are a type of malignant germ cell tumor composed of complicated cell types and are characterized by pathological features of immature neuroectodermal tubules/rosettes. However, there is a lack of understanding of patient-derived immature ovarian teratomas (PDT) at the single cell level. Moreover, whether stem cell lines derived from immature teratomas (CDT) can be used as models for research on PDT remains to be elucidated.

Methods

Single-cell RNA sequencing (scRNA-seq) and subsequent bioinformatic analysis was performed on three patient-derived immature ovarian teratomas (PDT) samples to reveal the heterogeneity, evolution trajectory, and cell communication within the tumor microenvironment of PDT. Validations were conducted in additional seven samples through multiplex immunofluorescence.

Result

A total of qualified 22,153 cells were obtained and divided into 28 clusters, which can match to the scRNA-seq annotation of CDT as well as human fetal Cell Atlas, but with higher heterogeneity and more prolific cell-cell crosstalk. Radial glia cells (tagged by SOX2) and immature neuron (tagged by DCX) exhibited mutually exclusive expression and differentiated along distinct evolutionary trajectory from cycling neural progenitors. Proportions of these neuroectodermal cell subtypes may play important roles in PDT through contributing to the internal heterogeneity of PDTs. Moreover, the immune cells in PDTs were infiltrated rather than teratoma-derived, with more abundant macrophage in immature neuron than those in radial glia cells, and the infiltrated macrophage subtypes (i.e., M1 and M2) were significantly correlated to clinical grade. Overall, suppressed evolution process and transcriptome regulation in neuroectodermal cells, reduced cell-cell crosstalk, higher M1/M2 proportion ratio, and enhanced T cell effects in tumor microenvironment are enriched in patients with favorable prognosis.

Discussion

This study provides a comprehensive profile of PDT at the single cell level, shedding light on the heterogeneity and evolution of neuroectodermal cells within PDTs and the role of immune cells within the tumor microenvironment. Also, our findings highlight the potential usage of CDTs as a model for research on PDT.

Human chorionic gonadotropin elevation in gliomatosis peritonei complicated with immature teratoma: A case report and review of the literature

RATIONALE

Gliomatosis peritonei (GP) refers to the implantation of glial tissue on the visceral and parietal peritoneal surface, often associated with immature teratoma. It is a rare condition and the pathogenesis is not fully understood. In addition, the indistinguishable radiological appearance of immature and mature teratomas, and limited pathology samples make an accurate diagnosis difficult in most cases. More importantly, patients are also at risk of recurrence after surgery. This report aims to describe the process of diagnosis and treatment of GP with immature teratoma.

PATIENT CONCERNS

The patient, a 38-year-old woman presented with GP complicated with immature teratoma after laparoscopic ovarian cyst excision.

DIAGNOSES

On physical examination, a 15 cm-pelvic mass, with poor mobility, was palpated. And tumor marker demonstrated a moderate increase in α-fetoprotein and carbohydrate antigen 125. We suspected malignancy according to the comprehensive preoperative evaluation, the postoperative pathology revealed an immature teratoma of the left ovary and complicated with gliomatosis peritonei. Three months after the second surgery, possible recurrence of immature teratoma was considered and the patient underwent the third laparotomy. But the postoperative pathology indicated mature teratoma and mature glial components in the pelvic lesions.

INTERVENTIONS AND OUTCOME

The patient underwent 2 more surgical resections after the initial resection and 3 cycles of bleomycin, etoposide, and cisplatin regimen chemotherapy. She was regularly followed up in the outpatient after surgery, and no recurrence has been reported in the pelvic cavity till date.

LESSON

The case illuminated that the primary diagnosis of GP complicated with immature teratoma is critical but highly challenging for both gynecologists and pathologists and more attention should be paid to "GP complicated with immature cystic teratoma" patients to avoid inappropriate treatment.

Characterization of rare histological subtypes of ovarian cancer based on molecular profiling

OBJECTIVE

Pan-cancer analysis across The Cancer Genome Atlas has revealed the molecular profiles of major types of carcinomas. High-grade serous carcinomas (HGSCs) have been characterized; however, in ovarian cancer, the profile of carcinoma with minor histopathological changes remains unclear. This study aimed to perform the molecular profiling of rare malignant ovarian tumors, including non-epithelial tumors (NETs; germ cell tumors and sex cord tumors) and clear cell carcinoma (CCC), to determine how they differ from the major HGSCs.

METHODS

Sixty-nine malignant ovarian tumors surgically resected at the Shizuoka Cancer Center between January 2014 and March 2019 were classified based on their histopathological types. The germline and somatic mutations in these carcinomas, including NETs, were determined using next-generation sequencing. Gene expression analysis was performed to investigate the major pathways of drug resistance, which is a characteristic of CCC.

RESULTS

NETs harbored copy-neutral loss of heterozygosity, accompanied by a high homologous recombination deficiency score; germline mutations of PALB2 and BARD1 were identified in two patients with NET. In chemoresistant CCC, the epithelial-mesenchymal transition pathway was activated regardless of ABC transporter expression.

CONCLUSION

This study revealed some genomic characteristics of rare malignant ovarian tumors, including NETs and CCC.

Delayed DNA replication in haploid human embryonic stem cells

Haploid human embryonic stem cells (ESCs) provide a powerful genetic system but diploidize at high rates. We hypothesized that diploidization results from aberrant DNA replication. To test this, we profiled DNA replication timing in isogenic haploid and diploid ESCs. The greatest difference was the earlier replication of the X Chromosome in haploids, consistent with the lack of X-Chromosome inactivation. We also identified 21 autosomal regions that had delayed replication in haploids, extending beyond the normal S phase and into G2/M. Haploid-delays comprised a unique set of quiescent genomic regions that are also underreplicated in polyploid placental cells. The same delays were observed in female ESCs with two active X Chromosomes, suggesting that increased X-Chromosome dosage may cause delayed autosomal replication. We propose that incomplete replication at the onset of mitosis could prevent cell division and result in re-entry into the cell cycle and whole genome duplication.

Molecular genetic evidence supporting diverse histogenic origins of germ cell tumors

Germ cell tumors (GCTs) originate during the histogenesis of primordial germ cells to mature gametes. Previous studies identified five histogenic mechanisms in ovarian mature teratomas (type I: failure of meiosis I; type II: failure of meiosis II; type III: duplication of the genome of a mature gamete; type IV: no meiosis; and type V: fusion of two different ova), but those of other GCTs remain elusive. In this study, we analyzed 84 GCTs of various pathologic types to identify the histogenesis using single-nucleotide polymorphism array by analyzing copy-neutral loss of heterozygosity (CN-LOH) and copy number alterations (CNAs). We detected types I and II in ovarian teratomas, type III in ovarian teratomas and yolk sac tumors (YSTs), and type IV in all GCT types. The GCTs with multiple-type histogenesis (I-IV) (ovarian mature/immature teratomas and YST) show meiotic CN-LOH with scant CNAs. Type IV-only GCTs are either with mitotic CN-LOH and abundant CNAs (seminoma, dysgerminoma, testicular mixed GCTs) or with scant CNAs and no CN-LOH (pediatric testicular and mediastinal teratomas). The development sequences of CN-LOH and CNA are different between the multiple type (I-IV) GCTs and type IV-only GCTs. We analyzed two different histologic areas in eight GCTs (one mature teratoma with a mucin-secreting adenoma, two immature teratomas, and five mixed GCTs). We found that GCTs (mature teratoma, immature teratoma, and mixed GCT) showed different genomic alterations between histologic areas, suggesting that genomic differences within a GCT could accompany histologic differentiation. Of note, we found evidence for collision tumors in a mixed GCT. Our data indicate that GCTs may have various histogenesis and intratumoral genomic differences, which might provide important information for the identification of GCTs, especially for those with different histologic areas. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Clonal evidence for the development of neuroblastoma with extensive copy-neutral loss of heterozygosity arising in a mature teratoma

Mature teratomas are usually benign tumors that rarely undergo malignant transformation. We report an advanced neuroblastoma arising in a mature teratoma of the ovary. Whole-exome sequencing identified extensive copy-neutral loss of heterozygosity (LOH) in both neuroblastoma and teratoma elements, suggesting that the neuroblastoma evolved from the teratoma. In addition, several truncating germline heterozygous variants in tumor suppressor genes, including RBL2 and FBXW12, became homozygous as a result of LOH. Collectively, we speculate that extensive LOH in teratoma cells may force heterozygous germline variants to become homozygous, which, in turn, may contribute to the development of neuroblastoma with the acquisition of additional chromosomal changes.

Single nucleotide polymorphism array and cytogenetic analyses of ovarian teratomas in children

Teratomas are the most common tumors in the ovary during childhood. Previous studies suggested that they may be derived from germ cells at any developmental stage from premeiotic oogonia through meiotic oocytes to post-meiotic ova. The majority of mature teratomas reveal normal karyotypes and immature teratomas show higher frequency of chromosomal abnormalities. We analyzed fresh tissue samples from 25 primary ovarian teratomas and three extraovarian deposits using whole genome single nucleotide polymorphism (SNP) array and karyotype. SNP array detected five patterns of copy neutral loss of heterozygosity (CN-LOH): failure of meiosis I (type I) in 12 tumors, failure of meiosis II (type II) in six tumors, endoreduplication of a haploid ovum (type III) in two tumors, premeiotic error (type IV) in four tumors, and both meiotic I and meiotic II errors in one tumor (type V). Three tumors with type I error had a single chromosome showing meiotic II error, and two tumors with type II error had a single chromosome showing premature sister-chromatid separation in meiosis I. Lack of recombination in multiple chromosomes in meiosis I were common, chromosomes 17, 7, 8, 21, and 22 were most commonly involved. Abnormal karyotypes were observed in four teratomas including +3, del(3q), +7, +8, +12, and i(18q). The extraovarian deposits revealed the same CN-LOH pattern as the primary teratoma. In summary, SNP array reveals the origin of ovarian teratoma and we propose a new mechanism that consecutive meiotic I and II errors occur frequently in ovarian teratomas.

Molecular Pathways and Targeted Therapies for Malignant Ovarian Germ Cell Tumors and Sex Cord-Stromal Tumors: A Contemporary Review

Non-epithelial ovarian tumors are heterogeneous and account for approximately 10% of ovarian malignancies. The most common subtypes of non-epithelial ovarian tumors arise from germ cells or sex cord and stromal cells of the gonads. These tumors are usually detected at an early stage, and management includes surgical staging and debulking. When indicated for advanced disease, most respond to chemotherapy; however, options for patients with refractory disease are limited, and regimens can be associated with significant toxicities, including permanent organ dysfunction, secondary malignancies, and death. Targeted therapies that potentially decrease chemotherapy-related adverse effects and improve outcomes for patients with chemotherapy-refractory disease are needed. Here, we review the molecular landscape of non-epithelial ovarian tumors for the purpose of informing rational clinical trial design. Recent genomic discoveries have uncovered recurring somatic alterations and germline mutations in subtypes of non-epithelial ovarian tumors. Though there is a paucity of efficacy data on targeted therapies, such as kinase inhibitors, antibody–drug conjugates, immunotherapy, and hormonal therapy, exceptional responses to some compounds have been reported. The rarity and complexity of non-epithelial ovarian tumors warrant collaboration and efficient clinical trial design, including high-quality molecular characterization, to guide future efforts.