A Population-Based Study of Patients With Small Cell Carcinoma of the Ovary, Hypercalcemic Type, Encompassing a 30-Year Period

CONTEXT.—

Small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is a rare and lethal tumor, characterized by hypercalcemia and early onset and associated with germline and somatic SMARCA4 variants.

OBJECTIVE.—

To identify all known cases of SCCOHT in the Slovenian population from 1991 to 2021 and present genetic testing results, histopathologic findings, and clinical data for these patients. We also estimate the incidence of SCCOHT.

DESIGN.—

We conducted a retrospective analysis of hospital medical records and data from the Slovenian Cancer Registry in order to identify cases of SCCOHT and obtain relevant clinical data. Histopathologic review of tumor samples with assessment of immunohistochemical staining for SMARCA4/BRG1 was undertaken to confirm the diagnosis of SCCOHT. Germline and somatic genetic analyses were performed using targeted next-generation sequencing.

RESULTS.—

Between 1991 and 2021, we identified 7 cases of SCCOHT in a population of 2 million. Genetic causes were determined in all cases. Two novel germline loss-of-function variants in SMARCA4 LRG_878t1:c.1423_1429delTACCTCA p.(Tyr475Ilefs*24) and LRG_878t1:c.3216-1G>T were identified. At diagnosis, patients were ages 21 to 41 and had International Federation of Gynecology and Obstetrics, or FIGO, stage IA-III disease. Outcomes were poor, with 6 of 7 patients dying of disease-related complications within 27 months from diagnosis. One patient had stable disease for 12 months while receiving immunotherapy.

CONCLUSIONS.—

We present genetic, histopathologic, and clinical characteristics for all cases of SCCOHT identified in the Slovenian population during a 30-year period. We report 2 novel germline SMARCA4 variants, possibly associated with high penetrance. We estimate the minimal incidence of SCCOHT to be 0.12 per 1 million per year.

Early-Onset Ovarian Cancer <30 Years: What Do We Know about Its Genetic Predisposition?

Ovarian cancer (OC) is one of the leading causes of cancer-related deaths in women. Most patients are diagnosed with advanced epithelial OC in their late 60s, and early-onset adult OC diagnosed ≤30 years is rare, accounting for less than 5% of all OC cases. The most significant risk factor for OC development are germline pathogenic/likely pathogenic variants (GPVs) in OC predisposition genes (including BRCA1, BRCA2, BRIP1, RAD51C, RAD51D, Lynch syndrome genes, or BRIP1), which contribute to the development of over 20% of all OC cases. GPVs in BRCA1/BRCA2 are the most prevalent. The presence of a GPV directs tailored cancer risk-reducing strategies for OC patients and their relatives. Identification of OC patients with GPVs can also have therapeutic consequences. Despite the general assumption that early cancer onset indicates higher involvement of hereditary cancer predisposition, the presence of GPVs in early-onset OC is rare (<10% of patients), and their heritability is uncertain. This review summarizes the current knowledge on the genetic predisposition to early-onset OC, with a special focus on epithelial OC, and suggests other alternative genetic factors (digenic, oligogenic, polygenic heritability, genetic mosaicism, imprinting, etc.) that may influence the development of early-onset OC in adult women lacking GPVs in known OC predisposition genes.

The effect of a single SMARCA4 exon deletion on RNA splicing: Implications for variant classification

BACKGROUND

Exon deletions are generally considered pathogenic, particularly when they are located out of frame. Here, we describe a pediatric, female patient presenting with hypercalcemia and a small cell carcinoma of the ovary, hypercalcemic type, and carrying a germline de novo SMARCA4 exon 14 deletion.

METHODS

The SMARCA4 deletion was identified by whole genome sequencing, and the effect on the RNA level was examined by gel- and capillary electrophoresis and nanopore sequencing.

RESULTS

The deletion was in silico predicted to be truncating, but RNA analysis revealed two major transcripts with deletion of exon 14 alone or exon 14 through 15, where the latter was located in-frame. Because the patient's phenotype matched that of other patients with pathogenic germline variants in SMARCA4, the deletion was classified as likely pathogenic.

CONCLUSION

We propose to include RNA analysis in classification of single-exon deletions, especially if located outside of known functional domains, as this can identify any disparate effects on the RNA and DNA level, which may have implications for variant classification using the American College of Medical Genetics and Genomics guidelines.

The role of chromatin remodeler SMARCA4/BRG1 in brain cancers: a potential therapeutic target

The chromatin remodeler SMARCA4/BRG1 is a key epigenetic regulator with diverse roles in coordinating the molecular programs that underlie brain tumour development. BRG1 function in brain cancer is largely specific to the tumour type and varies further between tumour subtypes, highlighting its complexity. Altered SMARCA4 expression has been linked to medulloblastoma, low-grade gliomas such as oligodendroglioma, high-grade gliomas such as glioblastoma and atypical/teratoid rhabdoid tumours. SMARCA4 mutations in brain cancer predominantly occur in the crucial catalytic ATPase domain, which is associated with tumour suppressor activity. However, SMARCA4 is opposingly seen to promote tumourigenesis in the absence of mutation and through overexpression in other brain tumours. This review explores the multifaceted interaction between SMARCA4 and various brain cancer types, highlighting its roles in tumour pathogenesis, the pathways it regulates, and the advances that have been made in understanding the functional relevance of mutations. We discuss developments made in targeting SMARCA4 and the potential to translate these to adjuvant therapies able to enhance current methods of brain cancer treatment.

SMARCA4 Mutations in Carcinomas of the Esophagus, Esophagogastric Junction, and Stomach

Deficiency of SMARCA4, a member of the SWI/SNF chromatin remodeling complex, has been described in a subset of undifferentiated gastroesophageal carcinomas with an aggressive clinical course. The full spectrum and frequency of SMARCA4 mutations in gastroesophageal cancer are unknown. We interrogated our institutional database and identified patients with gastroesophageal carcinomas who underwent cancer next-generation sequencing. We classified SMARCA4 mutations, assessed histologic features, and correlated SMARCA4 mutations with SMARCA4 protein expression by immunohistochemistry. SMARCA4 mutations were identified in gastroesophageal carcinomas from 107 (9.1%) of 1174 patients. Forty-nine SMARCA4 mutations, including 26 missense variants and 23 protein-truncating variants, were interpreted as pathogenic in 42 (3.6%) of 1174 patients. Thirty (71%) of 42 cancers with pathogenic SMARCA4 mutations were located in the esophagus or esophagogastric junction, and 12 cancers (29%) were located in the stomach. Sixty-four percent of carcinomas with pathogenic truncating SMARCA4 variants were poorly differentiated or undifferentiated compared with 25% of carcinomas with pathogenic missense variants. Eight of 12 carcinomas with truncating SMARCA4 variants and none of the 7 carcinomas with pathogenic SMARCA4 missense variants showed loss of SMARCA4 expression by immunohistochemistry. Four carcinomas with pathogenic truncating SMARCA4 variants were associated with Barrett esophagus. SMARCA4-mutated gastroesophageal cancers were enriched for APC (31%) and CTNNB1 (14%) mutations and exhibited similar frequency of TP53 (76%) and ARID1A (31%) mutations compared with gastroesophageal cancers without pathogenic SMARCA4 mutations. The median overall survival was 13.6 months for patients who presented with metastasis at diagnosis and 22.7 months for patients without metastasis. Overall, SMARCA4-mutated gastroesophageal cancers exhibit a spectrum of histologic grade, an association with Barrett esophagus, and a concurrent mutational pattern similar to SMARCA4-wild-type gastroesophageal adenocarcinomas. Although SMARCA4-deficient gastroesophageal carcinomas are associated with poorly differentiated and undifferentiated histology, the spectrum of histologic and molecular features suggests overlapping pathogenic pathways with conventional gastroesophageal adenocarcinomas.

Case report of bilateral ovarian fibromas associated with de novo germline variants in PTCH1 and SMARCA4

Background

Ovarian sex cord‐stromal tumors (OSCTs) are rare ovarian tumors that can develop from sex cord, stromal cells, or both. OSCTs can be benign or malignant. Bilateral and/or unilateral ovarian fibromas, a type of OSCT of the stromal cells, have been reported in individuals diagnosed with nevoid basal cell carcinoma syndrome (NBCCS). Calcified ovarian fibromas have been reported in 15–25% of individuals diagnosed with NBCCS while 75% of those cases occur bilaterally. The average age at diagnosis of OSCT/ovarian fibromas in patients with NBCSS is in the second to third decade compared with age 50 in the general population. Ovarian tumors are rare in pediatric populations.

Methods

The patient is a 5‐year‐old female diagnosed with bilateral ovarian fibromas at age 4. Multigene panel for the patient and subsequent targeted molecular evaluation of parents were completed. Histological evaluations on the surgically resected ovaries were performed for microscopic characterization of fibromas.

Results

Germline testing identified de novo heterozygous novel likely pathogenic variants in PTCH1 gene, exon 12 deletion, and an SMARCA4 splicing variant c.2002‐1G > A. Microscopic examination of bilateral tumors was consistent with an ovarian fibroma.

Conclusions

To our knowledge, this is the first report of bilateral benign ovarian fibroma in a child with a diagnosis of nevoid basal cell carcinoma syndrome (NBCCS) with a potential predisposition to Rhabdoid Tumor Predisposition Syndrome (RTPS).

Cytomorphologic features of SMARCA4-deficient non-small cell lung carcinoma and correlation with immunohistochemical and molecular features

BACKGROUND

SMARCA4/BRG1-deficient tumors and those that have loss of SMARCA/BRG1 have been described as various aggressive carcinomas and sarcomas, including a subset of non-small cell lung carcinoma (NSCLC). Cytomorphologic features of NSCLCs are yet to be described. The objective of this study was to evaluate the cytomorphologic features, immunohistochemical profile, and molecular profile of SMARCA4/BRG1-deficient NSCLC (SMARCA4-dNSCLC).

METHODS

The authors retrospectively searched for cases with SMARCA4/BRG1 functional loss alterations, which were identified in molecular studies and further confirmed by immunocytochemistry, and they reviewed the cytomorphologic features. Tumors with BRG1 loss were also stained with an extensive antibody panel. Molecular profiling and clinical information of the identified cases were scrutinized.

RESULTS

In total, 12 cytopathology cases from different anatomic sites were included. All cases showed variable expression of cytokeratin irrespective of type. One-half of cases had glandular features, followed by squamoid features, and poorly differentiated features. The most common cytologic features included sheets or papillary architecture, round or oval cell shapes, nuclear enlargement, moderate-to-marked pleomorphism, and coarse chromatin. Two cases with poorly differentiated cytomorphology had a predominance of single cells, scant cytoplasm, and macronucleoli. Variable expression of epithelial markers was noted in all cases. TP53 was the most frequently co-mutated gene in SMARCA4-dNSLCs.

CONCLUSIONS

This study demonstrates that SMARCA4-dNSCLCs can have a wide spectrum of cytomorphologic features, ranging from a relatively well differentiated adenocarcinoma to a poorly differentiated/undifferentiated carcinoma, with the majority of cases exhibiting some high-grade features, such as mitosis, apoptosis, necrosis, and marked pleomorphism.

SWI/SNF-deficient undifferentiated malignancies: where to draw the line†

Alterations in chromatin remodelling genes are increasingly recognised as drivers of undifferentiated malignancies. In atypical teratoid/rhabdoid tumours (ATRT) and extracranial rhabdoid tumours (ECRT), inactivation of SMARCB1 underlies >95% of cases. In the remainder, the culprit is another SWI-SNF family member, SMARCA4. By contrast, in small cell carcinoma of the ovary hypercalcemic type (SCCOHT), SMARCA4 deficiency is by far the most common driver mechanism, while SMARCB1 alterations are rarely seen. It is unclear why alterations are so heavily weighted towards one or another subunit based on site alone, but both have become essential markers for the diagnosis and management of these undifferentiated lesions. Core SMARCA4-deficient undifferentiated malignancies share an aggressive clinical course and show an overlapping morphologic phenotype. In their study, Andrianteranagna and colleagues used DNA methylation and gene expression profiling to compare two subsets of SMARCA4-deficient malignancies diagnosed as SCCOHT and ECRT. Their work gives further insight into the subtle molecular spectrum of SMARCA4-deficient tumours, and their distinction from ATRT and ECRT with SMARCB1 inactivation. The characterisation of these molecular features is likely to play an important role in the future as we try to establish a clinically meaningful framework for the diagnosis and management of these lesions. This article is protected by copyright. All rights reserved.

Malignant brain tumor in an infant showing histopathological features of yolk sac tumor but genetic and epigenetic features of AT/RT

SMARCA4 pathogenic variants are rarely detected in pediatric brain tumors other than atypical teratoid rhabdoid tumors (AT/RTs) without INI1 deficiency or in some cases of medulloblastoma. Here, we report an atypical intracranial immature teratoma that recurred as a yolk sac tumor with metastatic spinal and lung lesions. Sequencing of the tumor revealed two SMARCA4 variants, including a splice-site variant and a non-synonymous variant of uncertain significance. Additionally, the methylation signature of the tumor was close to that of AT/RTs. Our case might be a yet-unrecognized subtype of pediatric tumors in which inactivation of SMARCA4 contributes to the pathogenesis.

SMARCA4-deficient rhabdoid tumours show intermediate molecular features between SMARCB1-deficient rhabdoid tumours and small cell carcinomas of the ovary, hypercalcaemic type

Extracranial rhabdoid tumours (ECRTs) are an aggressive malignancy of infancy and early childhood. The vast majority of cases demonstrate inactivation of SMARCB1 (ECRT_SMARCB1 ) on a background of a remarkably stable genome, a low mutational burden, and no other recurrent mutations. Rarely, ECRTs can harbour the alternative inactivation of SMARCA4 (ECRT_SMARCA4 ) instead of SMARCB1. However, very few ECRT_SMARCA4 cases have been published to date, and a systematic characterization of ECRT_SMARCA4 is missing from the literature. In this study, we report the clinical, pathological, and genomic features of additional cases of ECRT_SMARCA4 and show that they are comparable to those of ECRT_SMARCB1. We also assess whether ECRT_SMARCB1 , ECRT_SMARCA4 , and small cell carcinomas of the ovary, hypercalcaemic type (SCCOHT) represent distinct or overlapping entities at a molecular level. Using DNA methylation and transcriptomics-based tumour classification approaches, we demonstrate that ECRT_SMARCA4 display molecular features intermediate between SCCOHT and ECRT_SMARCB1 ; however, ECRT_SMARCA4 appear to be more closely related to SCCOHT by DNA methylation. Conversely, both transcriptomics and DNA methylation show a larger gap between SCCOHT and ECRT_SMARCB1 , potentially supporting their continuous separate classification. Lastly, we show that ECRT_SMARCA4 display concomitant lack of SMARCA4 (BRG1) and SMARCA2 (BRM) expression at the protein level, similar to what is seen in SCCOHT. Overall, these results expand our knowledge on this rare tumour type and explore the similarities and differences among entities from the 'rhabdoid tumour' spectrum. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Current recommendations for clinical surveillance and genetic testing in rhabdoid tumor predisposition: a report from the SIOPE Host Genome Working Group

The rhabdoid tumor (RT) predisposition syndromes 1 and 2 (RTPS1 and 2) are rare genetic conditions rendering young children vulnerable to an increased risk of RT, malignant neoplasms affecting the kidney, miscellaneous soft-part tissues, the liver and the central nervous system (Atypical Teratoid Rhabdoid Tumors, ATRT). Both, RTPS1&2 are due to pathogenic variants (PV) in genes encoding constituents of the BAF chromatin remodeling complex, i.e. SMARCB1 (RTPS1) and SMARCA4 (RTPS2). In contrast to other genetic disorders related to PVs in SMARCB1 and SMARCA4 such as Coffin-Siris Syndrome, RTPS1&2 are characterized by a predominance of truncating PVs, terminating transcription thus explaining a specific cancer risk. The penetrance of RTPS1 early in life is high and associated with a poor survival. However, few unaffected carriers may be encountered. Beyond RT, the tumor spectrum may be larger than initially suspected, and cancer surveillance offered to unaffected carriers (siblings or parents) and long-term survivors of RT is still a matter of discussion. RTPS2 exposes female carriers to an ill-defined risk of small cell carcinoma of the ovaries, hypercalcemic type (SCCOHT), which may appear in prepubertal females. RT surveillance protocols for these rare families have not been established. To address unresolved issues in the care of individuals with RTPS and to propose appropriate surveillance guidelines in childhood, the SIOPe Host Genome working group invited pediatric oncologists and geneticists to contribute to an expert meeting. The current manuscript summarizes conclusions of the panel discussion, including consented statements as well as non-evidence-based proposals for validation in the future.

Coffin-Siris Syndrome 4-Related Spectrum in a Young Woman Caused by a Heterozygous SMARCA4 Deletion Detected by High-Resolution aCGH

Coffin-Siris Syndrome 4 is an autosomal dominant congenital malformation syndrome caused by heterozygous mutations in the SMARCA4 gene with its main features being intellectual disability, developmental delay, behavioral abnormalities, and hypoplastic or absent fifth fingernails and fifth distal phalanges. Here, we report a young woman with developmental delay, moderate intellectual disability, and bilateral sensorineural hearing loss, referred for genetic testing. High-resolution chromosomal microarray analysis identified a 428-kb deletion in chromosome 19 which included the SMARCA4 gene. We conclude that haploinsufficiency of SMARCA4 may be a valid pathophysiological mechanism leading to milder Coffin-Siris syndrome phenotypes.

The variability of SMARCA4-related Coffin-Siris syndrome: Do nonsense candidate variants add to milder phenotypes?

SMARCA4 encodes a central ATPase subunit in the BRG1-/BRM-associated factors (BAF) or polybromo-associated BAF (PBAF) complex in humans, which is responsible in part for chromatin remodeling and transcriptional regulation. Variants in this and other genes encoding BAF/PBAF complexes have been implicated in Coffin-Siris Syndrome, a multiple congenital anomaly syndrome classically characterized by learning and developmental differences, coarse facial features, hypertrichosis, and underdevelopment of the fifth digits/nails of the hands and feet. Individuals with SMARCA4 variants have been previously reported and appear to display a variable phenotype. We describe here a cohort of 15 unrelated individuals with SMARCA4 variants from the Coffin-Siris syndrome/BAF pathway disorders registry who further display variability in severity and degrees of learning impairment and health issues. Within this cohort, we also report two individuals with novel nonsense variants who appear to have a phenotype of milder learning/behavioral differences and no organ-system involvement.

A Systematic Literature Review of Whole Exome and Genome Sequencing Population Studies of Genetic Susceptibility to Cancer

The application of next-generation sequencing (NGS) technologies in cancer research has accelerated the discovery of somatic mutations; however, progress in the identification of germline variation associated with cancer risk is less clear. We conducted a systematic literature review of cancer genetic susceptibility studies that used NGS technologies at an exome/genome-wide scale to obtain a fuller understanding of the research landscape to date and to inform future studies. The variability across studies on methodologies and reporting was considerable. Most studies sequenced few high-risk (mainly European) families, used a candidate analysis approach, and identified potential cancer-related germline variants or genes in a small fraction of the sequenced cancer cases. This review highlights the importance of establishing consensus on standards for the application and reporting of variants filtering strategies. It also describes the progress in the identification of cancer-related germline variation to date. These findings point to the untapped potential in conducting studies with appropriately sized and racially diverse families and populations, combining results across studies and expanding beyond a candidate analysis approach to advance the discovery of genetic variation that accounts for the unexplained cancer heritability.

Small-Cell Carcinoma of the Ovary, Hypercalcemic Type-Genetics, New Treatment Targets, and Current Management Guidelines

Small-cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is a rare and highly aggressive ovarian malignancy. In almost all cases, it is associated with somatic and often germline pathogenic variants in SMARCA4, which encodes for the SMARCA4 protein (BRG1), a subunit of the SWI/SNF chromatin remodeling complex. Approximately 20% of human cancers possess pathogenic variants in at least one SWI/SNF subunit. Because of their role in regulating many important cellular processes including transcriptional control, DNA repair, differentiation, cell division, and DNA replication, SWI/SNF complexes with mutant subunits are thought to contribute to cancer initiation and progression. Fewer than 500 cases of SCCOHT have been reported in the literature and approximately 60% are associated with hypercalcemia. SCCOHT primarily affects females under 40 years of age who usually present with symptoms related to a pelvic mass. SCCOHT is an aggressive cancer, with long-term survival rates of 30% in early-stage cases. Although various treatment approaches have been proposed, there is no consensus on surveillance and therapeutic strategy. An international group of multidisciplinary clinicians and researchers recently formed the International SCCOHT Consortium to evaluate current knowledge and propose consensus surveillance and therapeutic recommendations, with the aim of improving outcomes. Here, we present an overview of the genetics of this cancer, provide updates on new treatment targets, and propose management guidelines for this challenging cancer.

Malignant Rhabdoid Tumor, an Aggressive Tumor Often Misclassified as Small Cell Variant of Hepatoblastoma

The clinical management of pediatric liver tumors involves stratification into risk groups. One previously defined, high-risk group of hepatoblastomas is the small cell undifferentiated variant. In light of molecular studies showing SMARCB1 deletion in these tumors, it is now recognized that most small cell, undifferentiated liver tumors represent an aggressive unrelated tumor—the malignant rhabdoid tumor (MRT). SMARCB1 is a member of the chromatin remodeling SWI/SNF complex and encodes the INI1 protein. The histologic diagnosis of MRT is currently based on INI1 negative immunoreactivity and the presence of rhabdoid morphology. INI1-negative small cell liver tumors lacking classic rhabdoid morphology are often misclassified as small cell undifferentiated hepatoblastomas (SCUD-HB), according to the current classification. Pediatric liver tumors diagnosed between 2003–2017 as SCUD-HB (four cases) or MRT (two cases) were identified from the Columbia University Pathology Department Archives. All tumors were associated with normal or low serum alpha fetoprotein levels, and showed an absence of immunohistochemical staining of hepatocellular markers (Hep-par1, Arginase) and loss of INI1 staining. Two cases were initially diagnosed as MRT, one with prominent rhabdoid morphology, the other with predominant small cell morphology. The remaining four cases with small cell morphology were classified as SCUD-HB. Ancillary molecular studies confirmed the loss of SMARCB1, supporting the diagnosis of MRT in all cases, proving morphology an unreliable criterion. It is critical to eliminate the term INI1-negative hepatoblastoma from the current classification scheme, and classify INI1-negative tumors as MRT, particularly since high-risk HB-chemotherapy regimens are not effective for treating MRT.

SMARCA4 inactivation defines a subset of undifferentiated uterine sarcomas with rhabdoid and small cell features and germline mutation association

A rare subset of aggressive SMARCA4-deficient uterine sarcomas has been recently proposed, with only a limited number of cases having been previously described. Here, we identify 16 additional cases of SMARCA4-deficient uterine sarcoma from the database of a large, CLIA-certified and CAP-accredited, reference molecular laboratory, and we expand on their clinicopathological and genomic features. Median patient's age was 49 years (range 32-70). Most tumors were aggressive with distant metastasis. SMARCA4-deficient uterine sarcoma demonstrated predominantly rhabdoid or large epithelioid cells with abundant cytoplasm, but also had varying degrees of small cell and spindle cell morphology. Tumors were microsatellite stable and exhibited no other or only few co-occurring genomic alterations by comprehensive genomic profiling. We discovered one patient, who developed SMARCA4-deficient uterine sarcoma at the age of 55, had a germline SMARCA4 mutation, whose daughter had previously died of small cell carcinoma of the ovary, hypercalcemic type, at the age of 32. Our data support the notion that SMARCA4 inactivation is the driver oncogenic event of a morphologically and molecularly distinct form of uterine sarcoma. Identification of SMARCA4-deficient uterine sarcomas may be clinically important due to their aggressive behavior, germline association, and emerging targeted therapies.

Germline Genetics and Childhood Cancer: Emerging Cancer Predisposition Syndromes and Psychosocial Impacts

PURPOSE OF REVIEW

Germline genetic variants contribute to a substantial proportion of cases of cancer in childhood. The purpose of this review is to describe two emerging pediatric cancer predisposition syndromes, including published surveillance protocols, as well as the psychological impacts related to childhood cancer predisposition.

RECENT FINDINGS

DICER1 syndrome is pleotropic, predisposing to a variety of tumors and likely phenotypically broader than currently realized. Rhabdoid tumor predisposition syndrome carries a risk for development of aggressive malignancies occurring in nearly any tissue. New pediatric hereditary cancer syndromes are likely to be identified as genetic evaluation evolves. Advantages and disadvantages of genetic testing and surveillance protocols need to be discussed with patients and families in a team-based approach, with the input of a genetic counselor holding expertise in pediatric cancer predisposition. Finally, literature on psychosocial impacts of hereditary cancer syndromes in pediatric patients is sparse, necessitating further research.

[Pathological and molecular features of malignancies underlined by BAF complexes inactivation]

BAF complexes are chromatin remodelling complexes made up of 15 subunits which overview transcription regulation. A subset of their subunits are notoriously linked to cancer, with the examples of SMARCB1, SMARCA4, ARID1A/1B and PBRM1. The complexes act as tumor suppressor genes, commonly mutated in a wide array of malignancies with an overrepresentation of sarcomas and tumors of the central nervous system. The recurrent inactivation of their genes points towards their driving role in the tumorigenesis of SMARCB1 in malignant rhabdoid tumors and SMARCA4 in small cell carcinoma of the ovary, hypercalcemic type. These tumors are morphologically similar composed of solid sheets of cells displaying vesicular nuclei dotted with clear chromatin and conspicuous nucleoli. Genomically, they share simple diploid profiles with no other alterations than in the culprit gene. Other mesenchymal tumors, distinct from malignant rhabdoid tumors are associated with BAF alterations, namely epithelioid sarcomas, SMARCA4-deficient thoracic sarcomas. BAF subunits are mostly inactivated through mutations or deletions but also occur through translocations in medullary carcinoma of the kidney and synovial sarcomas. Apart from tumors displaying recurrent alterations of the complexes, some variants or tumor variants display BAF alterations, including epithelioid malignant peripheral nerve sheet tumors and poorly differentiated chordomas. Lastly, some malignancies display low frequency of BAF alterations, in keeping with their passenger role in tumorigenesis with the example of dedifferentiated carcinomas, especially in colon, lung and uterus. BAF complexes alterations correlate with morphological features recognizable by microscopy, paving the way for their routine diagnosis and potential therapeutic prospects.

Remodeling the cancer epigenome: mutations in the SWI/SNF complex offer new therapeutic opportunities

INTRODUCTION

Cancer genome sequencing studies have discovered mutations in members of the SWItch/Sucrose Non-Fermentable (SWI/SNF) chromatin-remodeling complex in nearly 25% of human cancers. The SWI/SNF complex, first discovered in S. cerevisiae, shows strong conservation from yeast to Drosophila to mammals, contains approximately 10-12 subunits and regulates nucleosome positioning through the energy generated by its ATPase subunits. The unexpected finding of frequent mutations in the complex has fueled studies to identify the mechanisms that drive tumor development and the accompanying therapeutic vulnerabilities. Areas covered: In the review, we focus upon the potential roles different SWI/SNF subunit mutations play in human oncogenesis, their common and unique mechanisms of transformation and the potential for translating these mechanisms into targeted therapies for SWI/SNF-mutant tumors. Expert opinion: We currently have limited insights into how mutations in different SWI/SNF subunits drive the development of human tumors. Because the SWI/SNF complex participates in a broad range of normal cellular functions, defining specific oncogenic pathways has proved difficult. In addition, therapeutic options for SWI/SNF-mutant cancers have mainly evolved from high-throughput screens of cell lines with mutations in different subunits. Future studies should follow a more coherent plan to pinpoint common vulnerabilities among these tumors.

Management of Gynecologic Cancers In Relation to Genetic Predisposition

OBJECTIVE

To review hereditary gynecologic cancer syndromes and outline current clinical management considerations.

DATA SOURCES

Retrieved articles and guidelines dated 2013-2018 from PubMed, National Comprehensive Cancer Network, American College of Medical Genetics and Genomics, American College of Obstetricians and Gynecologists, American Cancer Society, National Cancer Institute, Centers for Disease Control and Prevention, and National Institutes of Health databases.

CONCLUSION

Advances in genetic testing technology have allowed for the identification of a growing number of patients with genetic mutations associated with hereditary cancer. Individuals with a hereditary predisposition to cancer may qualify for targeted drug therapies, risk-reducing surgeries, and/or high-risk cancer surveillance depending on the specific gene mutation(s) they harbor. Furthermore, there are clinical implications for relatives.

IMPLICATIONS FOR NURSING PRACTICE

This article is an educational guide for oncology nurses who often play a key role in identifying patients at risk for hereditary cancer, prompting referrals for genetic evaluation, and providing follow-up care for these patients.

An In-Depth Look at Small Cell Carcinoma of the Ovary, Hypercalcemic Type (SCCOHT): Clinical Implications from Recent Molecular Findings

Small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is a highly aggressive cancer in young women. The histogenesis remains unclear although a potential origin of germ cells has been suggested recently. The high throughput next generation sequencing techniques have facilitated the identification of inactivating SMARCA4 mutations as the driver of SCCOHT. These findings may greatly impact on the prevention, diagnosis, molecular classification and treatment of SCCOHTs. The SMARCA4 mutations, typically associated with dual loss of BRG1 and BRM expression, are highly sensitive and specific for the diagnosis of SCCOHT. Germline mutations of SMARCA4 support familial SCCOHT with a critical requirement of genetic counseling and possible prophylactic surgery for carriers. SCCOHT, malignant atypical teratoid/rhabdoid tumors, thoracic sarcomas and some undifferentiated carcinomas harbor rhabdoid morphology and mutations in the SMARC genes, generating an emerging molecular classification of SMARC-mutated tumors. A multi-modality treatment approach consisting of surgery and high dose multi-agent chemotherapy in atypical teratoid/rhabdoid tumors may have potential benefits for SCCOHT patients. Preliminary studies have implicated that the inhibitors targeting EZH2 and the receptor tyrosine kinase, and anti-PD-L1 immunotherapy might be potentially effective for SCCOHT patients. These recent advances on molecular genetics, diagnosis and treatment of SCCOHT address the necessity of multiple institutional collaboration work among oncologist, pathologist, genomic scientist, geneticist, molecular biologist, and pharmacologist.

Ovarian small cell carcinoma in one of a pair of monozygous twins

One of a pair of monozygous twins was diagnosed and died of small cell carcinoma of the ovary of hypercalcemic type (SCCOHT) at the age of 30 years. Her sister remained unaffected and was very concerned about her risk for developing SCCOHT. By performing comprehensive molecular analysis using whole exome sequencing (WES) approach, we showed that the deceased twin's tumour has bi-allelic somatic genetic defects (a pathogenic frameshift deletion in SMARCA4 and LOH on chr19p). Results of WES of constitutional DNA from her unaffected sister were confirmatory. Based on our findings, we concluded that the living twin is not at risk for SCCOHT and does not need to consider preventive oophorectomy.

Cancer Surveillance in Gorlin Syndrome and Rhabdoid Tumor Predisposition Syndrome

Gorlin syndrome and rhabdoid tumor predisposition syndrome (RTPS) are autosomal dominant syndromes associated with an increased risk of childhood-onset brain tumors. Individuals with Gorlin syndrome can manifest a wide range of phenotypic abnormalities, with about 5% of family members developing medulloblastoma, usually occurring in the first 3 years of life. Gorlin syndrome is associated with germline mutations in components of the Sonic Hedgehog pathway, including Patched1 (PTCH1) and Suppressor of fused (SUFU)SUFU mutation carriers appear to have an especially high risk of early-onset medulloblastoma. Surveillance MRI in the first years of life in SUFU mutation carriers is, therefore, recommended. Given the risk of basal cell carcinomas, regular dermatologic examinations and sun protection are also recommended. Rhabdoid tumors (RT) are tumors initially defined by the descriptive "rhabdoid" term, implying a phenotypic similarity with rhabdomyoblasts at the microscopic level. RTs usually present before the age of 3 and can arise within the cranium as atypical teratoid/rhabdoid tumors or extracranially, especially in the kidney, as malignant rhabdoid tumors. However, RTs of both types share germline and somatic mutations in SMARCB1 or, more rarely, SMARCA4, each of which encodes a chromatin remodeling family member. SMARCA4 mutations are particularly associated with small cell carcinoma of the ovary, hypercalcemic type (SCCOHT). The outcome following a diagnosis of any of these tumors is often poor, and the value of surveillance is unknown. International efforts to determine surveillance protocols are underway, and preliminary recommendations are made for carriers of SMARCB1 and SMARCA4 mutations. Clin Cancer Res; 23(12); e62-e67. ©2017 AACRSee all articles in the online-only CCR Pediatric Oncology Series.

The hereditary nature of small cell carcinoma of the ovary, hypercalcemic type: two new familial cases

Small cell carcinoma of the ovary, hypercalcemic type, (SCCOHT) is the most common undifferentiated ovarian cancer in women aged under 40 years. SCCOHT is a monogenic disease, characterized by germline and somatic SMARCA4 mutations. Recent studies have stressed its morphological and clinical similarity to malignant rhabdoid tumours, which are usually caused by mutations in the related gene, SMARCB1. While familial tumours are rare, the incidence of germline mutations is relatively high, with up to 43% of SCCOHTs and 35% of rhabdoid tumours caused by germline mutations in SMARCA4 and SMARCB1, respectively. We report two new familial cases of SCCOHT. Affected members in both families and the associated tumours were found to carry SMARCA4 germline and somatic mutations, respectively, leading to loss of SMARCA4 protein expression in the tumours. Despite the rarity of familial SCCOHT, the high incidence of germline mutations is important to note, as without a family history of the disease, the hereditary nature of SCCOHT may be missed, especially if the mutation was inherited from the father or acquired de novo. The similarity between SCCOHT and rhabdoid tumours should be recognized, as infant carriers of SMARCA4 mutations may be at risk for these tumours in addition to SCCOHT.

Hereditary SWI/SNF complex deficiency syndromes

The SWItch Sucrose non-fermentable (SWI/SNF) complex is a highly conserved multi-subunit complex of proteins encoded by numerous genes mapped to different chromosomal regions. The complex regulates the process of chromatin remodelling and hence plays a central role in the epigenetic regulation of gene expression, cell proliferation and differentiation. During the last three decades, the SWI/SNF complex has been increasingly recognized as a central molecular event driving the initiation and/or progression of several benign and malignant neoplasms of different anatomic origin and having diverse histomorphological appearance. Atypical teratoid/rhabdoid tumors (AT/RT) and renal/extrarenal malignant rhabdoid tumors of childhood, epithelioid sarcoma and small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) represent the most commonly recognized SWI/SNF-driven neoplasms. Approximately one-third of pediatric malignant rhabdoid tumors are linked to germline SWI/SNF alterations (SMARCB1/INI1, rarely SMARCA4) resulting in occasional familial clustering of these highly aggressive malignancies (so-called rhabdoid tumor predisposition syndrome, RTPS, types 1 and 2, respectively). However, more recently, inherited SWI/SNF-deficiency has been linked to several benign syndromic tumors including a subset of familial schwannomatosis (linked to SMARCB1) and multiple meningiomas (linked to SMARCE1) as well as others. Beyond neoplasms, several congenital developmental functional disorders such as Coffin-Siris syndrome and intellectual disability are now known to be SWI/SNF-related. The latter are essentially not associated with SWI/SNF-driven neoplasms, although at least anecdotal cases have documented concurrence of both neoplastic and developmental disorders. This review summarizes the most important SWI/SNF-driven diseases with a main focus on neoplasms.

BAFfling pathologies: Alterations of BAF complexes in cancer

To activate or repress specific genes, chromatin is constantly modified by chromatin-remodeling complexes. Among these complexes, the SWItch/Sucrose Non-Fermenting (SWI/SNF) complex, also referred to as BRG1-Associated Factor (BAF) complex, moves the nucleosome along chromatin using energy provided by ATP hydrolysis. In mammalian organisms, the SWI/SNF complex is composed of 10-15 subunits, depending on cell type, and a defect in one of these subunits can have dramatic consequences. In this review we will focus on the alterations identified in the SWI/SNF (BAF) complex subunits that lead to cancerous pathologies. While SMARCB1 was the first mutated subunit to be reported in a majority of malignant rhabdoid tumors, the advent of next-generation sequencing allowed the discovery of mutations in various SWI/SNF subunits within a broad spectrum of cancers. In most cases, the mutation leads to a loss of expression or to a truncated subunit unable to perform its function. Even though it is now commonly acknowledged that approximately 20% of all cancers present a mutation in a SWI/SNF subunit, some cancers are associated to a specific alteration of a SWI/SNF subunit, which acts either as tumor suppressor genes or as oncogenes, and therefore constitute diagnostic or prognostic biomarkers. Consistently, therapeutic strategies targeting SWI/SNF subunits or the genes affected downstream have been revealed to treat cancers.

Atypical teratoid/rhabdoid tumor with retained INI1 (SMARCB1) expression and loss of BRG1 (SMARCA4)

Atypical teratoid/rhabdoid tumor (AT/RT) is a rare, highly aggressive malignancy of the central nervous system (CNS) usually diagnosed in infancy or childhood, most often characterized by loss of expression of the SMARCB1 gene product integrase interactor 1 (INI1) protein. We report a case of AT/RT in a 3 month old boy with retained expression of INI1 by immunohistochemistry. Additional testing demonstrated loss of expression of the SMARCA4 gene product Brahma-related gene 1 (BRG1) protein by immunohistochemistry, confirmed by next generation sequencing showing a nonsense mutation in SMARCA4. This case illustrates that positivity for INI1 does not rule out a diagnosis of AT/RT, and additional testing, including BRG1/SMARCA4 analysis, is warranted in cases where clinical suspicion is high.

Comprehensive genomic profiling reveals inactivating SMARCA4 mutations and low tumor mutational burden in small cell carcinoma of the ovary, hypercalcemic-type

OBJECTIVE

Small cell carcinoma of the ovary, hypercalcemic-type (SCCOHT) is a rare, extremely aggressive neoplasm that usually occurs in young women and is characterized by deleterious germline or somatic SMARCA4 mutations. We performed comprehensive genomic profiling (CGP) to potentially identify additional clinically and pathophysiologically relevant genomic alterations in SCCOHT.

METHODS

CGP assessment of all classes of coding alterations in up to 406 genes commonly altered in cancer and intronic regions for up to 31 genes commonly rearranged in cancer was performed on 18 SCCOHT cases (16 exhibiting classic morphology and 2 cases exhibiting exclusive a large cell variant morphology). In addition, a retrospective database search for clinically advanced ovarian tumors with genomic profiles similar to SCCOHT yielded 3 additional cases originally diagnosed as non-SCCOHT.

RESULTS

CGP revealed inactivating SMARCA4 alterations and low tumor mutational burden (TMB) (<6mutations/Mb) in 94% (15/16) of SCCOHT with classic morphology. In contrast, both (2/2) cases exhibiting only large cell variant morphology were hypermutated (TMB scores of 90 and 360mut/Mb) and were wildtype for SMARCA4. In our retrospective search, an index ovarian cancer patient harboring inactivating SMARCA4 alterations, initially diagnosed as endometrioid carcinoma, was re-classified as SCCOHT and responded to an SCCOHT chemotherapy regimen.

CONCLUSION

The vast majority of SCCOHT demonstrate genomic SMARCA4 loss with only rare co-occurring alterations. Our data support a role for CGP in the diagnosis and management of SCCOHT and of other lesions with overlapping histological and clinical features, since identifying the former by genomic profile suggests benefit from an appropriate regimen and treatment decisions, as illustrated by an index patient.

Ovarian sex-cord stromal tumours and small cell tumours: Pathological, genetic and management aspects

Non-epithelial ovarian cancers (NEOC) constitute a group of uncommon malignancies and their treatment is still a challenging task. Collectively, these tumours account for about 10% of all ovarian cancers and occur in all age groups from childhood to old-age. They include malignancies of germ cell origin, sex cord-stromal cell origin, and a variety of extremely rare ovarian cancers, such as small-cell carcinomas and sarcomas. Each of these classifications encompasses multiple histologic subtypes. It is imperative that these rare tumours are managed with accurate diagnosis, staging, and treatment, to optimise the outcome. The aetiology and molecular origins of each sub-group of NEOC remain largely unresolved, and international cooperation to promote high quality translational research is crucial. Much effort has been made into researching the molecular mechanisms underlying epithelial ovarian cancers, but far less is known about the genetic changes in NEOC. In this article, it is provided an overview of the current knowledge on the incidence, clinical presentation, pathology, genetics, therapeutic interventions, survival and prognostic factors of adult and juvenile granulosa cell tumours (GrCT), Sertoli-Leydig Cell tumours (SLCT) and small cell carcinoma of the ovary. We also consider future potential therapeutic targets in these rare cancers.

Uterine Tumor Resembling Ovarian Sex Cord Tumor (UTROSCT) Commonly Exhibits Positivity With Sex Cord Markers FOXL2 and SF-1 but Lacks FOXL2 and DICER1 Mutations

Uterine tumor resembling ovarian sex cord tumor (UTROSCT) is a rare neoplasm which morphologically and immunohistochemically exhibits overlap with an ovarian sex cord tumor. Although many of these neoplasms are positive with markers of ovarian sex cord-stromal tumors, staining is often limited and the pathogenesis of UTROSCT is unknown. To further explore the sex cord lineage of UTROSCT, we studied 19 of these neoplasms and examined the expression of 2 recently described markers of ovarian sex cord-stromal tumors, FOXL2, and steroidogenic factor-1. We also undertook FOXL2 and DICER1 mutation analysis in these cases; a somatic missense mutation in codon C134W (402C→G) of FOXL2 gene has been demonstrated in the vast majority (>95%) of ovarian adult granulosa cell tumors and somatic DICER1 mutations are found in approximately 60% of ovarian Sertoli-Leydig cell tumors. Ten of 19 cases (53%) exhibited nuclear immunoreactivity with FOXL2 and 11 of 19 (58%) exhibited nuclear staining with steroidogenic factor-1. Neither FOXL2 nor DICER1 mutations were identified in any case where there was sufficient tumor tissue for analysis (18 and 9 cases, respectively). Despite exhibiting an immunophenotype characteristic of a sex cord-stromal tumor, mutations in FOXL2 and DICER1, the 2 most common mutations hitherto reported in ovarian sex cord-stromal tumors, are not a feature of UTROSCT.

SMARCA4 inactivating mutations cause concomitant Coffin-Siris syndrome, microphthalmia and small-cell carcinoma of the ovary hypercalcaemic type

SMARCA4 chromatin remodelling factor is mutated in 11% of Coffin–Siris syndrome (CSS) patients and in almost all small‐cell carcinoma of the ovary hypercalcaemic type (SCCOHT) tumours. Missense mutations with gain‐of‐function or dominant‐negative effects are associated with CSS, whereas inactivating mutations, leading to loss of SMARCA4 expression, have been exclusively found in SCCOHT. We applied whole‐exome sequencing to study a 15‐year‐old patient with mild CSS who concomitantly developed SCCOHT at age 13 years. Interestingly, our patient also showed congenital microphthalmia, which has never previously been reported in CSS patients. We detected a de novo germline heterozygous nonsense mutation in exon 19 of SMARCA4 (c.2935C > T;p.Arg979*), and a somatic frameshift mutation in exon 6 (c.1236_1236delC;p.Gln413Argfs*88), causing complete loss of SMARCA4 immunostaining in the tumour. The immunohistochemical findings are supported by the observation that the c.2935C > T mutant transcript was detected by reverse transcription polymerase chain reaction at a much lower level than the wild‐type allele in whole blood and the lymphoblastoid cell line of the proband, confirming nonsense‐mediated mRNA decay. Accordingly, immunoblotting demonstrated that there was approximately half the amount of SMARCA4 protein in the proband's cells as in controls. This study suggests that SMARCA4 constitutional mutations associated with CSS are not necessarily non‐truncating, and that haploinsufficiency may explain milder CSS phenotypes, as previously reported for haploinsufficient ARID1B. In addition, our case supports the dual role of chromatin remodellers in developmental disorders and cancer, as well as the involvement of SMARCA4 in microphthalmia, confirming previous findings in mouse models and the DECIPHER database. Finally, we speculate that mild CSS might be under‐recognized in a proportion of SCCOHT patients harbouring SMARCA4 mutations. © 2017 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Loss of SMARCA4 Expression Is Both Sensitive and Specific for the Diagnosis of Small Cell Carcinoma of Ovary, Hypercalcemic Type

Small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is a rare ovarian neoplasm that occurs in young women and has a poor prognosis. The histologic diagnosis of SCCOHT can be challenging due to its rarity and relatively nonspecific histologic features, which range from the classic, first-described small cell morphology to a pattern in which there are large cells with abundant eosinophilic cytoplasm. Many entities can be in the differential diagnosis and to date, immunohistochemical stains have shown no distinctive profile and have been of limited aid. SMARCA4 (also known as BRG1) mutations have recently been reported at high frequency in these tumors. SMARCA4 is an important component of the SWI/SNF complex that regulates gene expression through alteration of nucleosome conformation. Studies to date have suggested that immunohistochemical loss of expression of SMARCA4 is associated with the presence of a SMARCA4 mutation in most cases. In this study, the sensitivity and specificity of the immunohistochemical loss of SMARCA4 expression for the diagnosis of SCCOHT is examined in the context of the differential diagnosis with other primary or metastatic ovarian tumors. All but one of the SCCOHT showed loss of SMARCA4 expression (16/17; 94%), while of 279 other tumors tested, only two tumors (one clear cell carcinoma and one ovarian melanoma) showed loss of SMARCA4 expression. We conclude that SMARCA4 immunohistochemistry is highly sensitive and specific for a diagnosis of SCCOHT and is of clinical utility in the differential diagnosis of poorly differentiated ovarian tumors.

Dual loss of the SWI/SNF complex ATPases SMARCA4/BRG1 and SMARCA2/BRM is highly sensitive and specific for small cell carcinoma of the ovary, hypercalcaemic type

Small cell carcinoma of the ovary, hypercalcaemic type (SCCOHT) is a lethal and sometimes familial ovarian tumour of young women and children. We and others recently discovered that over 90% of SCCOHTs harbour inactivating mutations in the chromatin remodelling gene SMARCA4 with concomitant loss of its encoded protein SMARCA4 (BRG1), one of two mutually exclusive ATPases of the SWI/SNF chromatin remodelling complex. To determine the specificity of SMARCA4 loss for SCCOHT, we examined the expression of SMARCA4 by immunohistochemistry in more than 3000 primary gynaecological tumours. Among ovarian tumours, it was only absent in clear cell carcinoma (15 of 360, 4%). In the uterus, it was absent in endometrial stromal sarcomas (4 of 52, 8%) and high‐grade endometrioid carcinomas (2 of 338, 1%). Recent studies have shown that SMARCA2 (BRM), the other mutually exclusive ATPase of the SWI/SNF complex, is necessary for survival of tumour cells lacking SMARCA4. Therefore, we examined SMARCA2 expression and discovered that all SMARCA4‐negative SCCOHTs also lacked SMARCA2 protein by IHC, including the SCCOHT cell lines BIN67 and SCCOHT1. Among ovarian tumours, the SMARCA4/SMARCA2 dual loss phenotype appears completely specific for SCCOHT. SMARCA2 loss was not due to mutation but rather from an absence of mRNA expression, which was restored by treatment with the histone deacetylase inhibitor trichostatin A. Re‐expression of SMARCA4 or SMARCA2 inhibited the growth of BIN67 and SCCOHT1 cell lines. Our results indicate that SMARCA4 loss, either alone or with SMARCA2, is highly sensitive and specific for SCCOHT and that restoration of either SWI/SNF ATPase can inhibit the growth of SCCOHT cell lines. © 2015 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Small cell carcinoma of the ovary-hypercalcemic type (SCCOHT): A review of 47 cases

OBJECTIVE

Small cell carcinoma of the ovary-hypercalcemic type (SCCOHT) is a rare disease with a poor prognosis. SCCOHT has recently been shown to be associated with SMARCA4 gene mutations as well as molecular and genetic similarities to malignant rhabdoid tumors (MRT). The objective of our study is to describe the clinical characteristics, treatment modalities and outcomes of 47 patients with SCCOHT.

METHODS

We performed a retrospective analysis of 47 patients with SCCOHT evaluated at MD Anderson Cancer Center between 1990 and 2014. Medical records were reviewed for demographic information, pathologic findings, treatment regimens and outcomes.

RESULTS

Median age at diagnosis was 30 years (range 5-46). All patients underwent surgery with unilateral salpingo-oophorectomy (USO) performed in 26 patients (55%), and hysterectomy with bilateral salpingooophorectomy (BSO) in 21 patients (45%). Sixteen patients (34.0%) had stage I disease, six (12.8%) stage II, 23 (48.9%) stage III, and two patients (4.3%) had stage IV disease. Information on adjuvant treatment was available for 43 patients: 83.3% received chemotherapy alone, 9.5% chemotherapy followed by radiotherapy, 2.4% chemoradiation, and 4.8% did not receive any adjuvant therapy. Median follow-up was 13.2 months (range, 0.1 to 210.7) with a median overall survival of 14.9 months. Multi-agent chemotherapy and radiotherapy were associated with a better prognosis.

CONCLUSION

Our findings suggest that aggressive therapy including multi-agent chemotherapy and possibly radiotherapy may extend survival. Further study is needed to improve outcomes in these patients including the adoption of systemic therapies used in MRT as well as the development of novel agents targeting specific mutations.

SMARCA4 inactivation defines a group of undifferentiated thoracic malignancies transcriptionally related to BAF-deficient sarcomas

While investigating cohorts of unclassified sarcomas by RNA sequencing, we identified 19 cases with inactivation of SMARCA4, which encodes an ATPase subunit of BAF chromatin-remodeling complexes. Clinically, the cases were all strikingly similar, presenting as compressive mediastino-pulmonary masses in 30- to 35-year-old adults with a median survival time of 7 months. To help define the nosological relationships of these tumors, we compared their transcriptomic profiles with those of SMARCA4-mutated small-cell carcinomas of the ovary, hypercalcemic type (SCCOHTs), SMARCB1-inactivated malignant rhabdoid tumors (MRTs) and lung carcinomas (of which 10% display SMARCA4 mutations). Gene profiling analyses demonstrated that these tumors were distinct from lung carcinomas but related to MRTs and SCCOHTs. Transcriptome analyses, further validated by immunohistochemistry, highlighted strong expression of SOX2, a marker that supports the differential diagnosis of these tumors from SMARCA4-deficient lung carcinomas. The prospective recruitment of cases confirmed this new category of 'SMARCA4-deficient thoracic sarcomas' as readily recognizable in clinical practice, providing opportunities to tailor their therapeutic management.

Biallelic somatic SMARCA4 mutations in small cell carcinoma of the ovary, hypercalcemic type (SCCOHT)

Small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is a rare, aggressive tumor that primarily affects young women. SCCOHT has recently been identified as a monogenic disorder caused by germline and/or somatic SMARCA4 mutations. We describe a 15-year-old Caucasian female with a SCCOHT harboring a previously unreported somatic mutation in the SMARCA4 gene (c.1757delA; p.K586.fs) with loss of heterozygosity. No germline mutation was identified. Subsequent immunohistochemical staining confirmed loss of SMARCA4 protein. These molecular findings will aid with SCCOHT diagnosis through immunohistochemical staining for SMARCA4 and in the future may have implications for the management of this disease.

Germline SMARCA4 mutations in patients with ovarian small cell carcinoma of hypercalcemic type

BACKGROUND

SMARCA4 mutations have recently been identified as driving lesions of the ovarian small cell carcinoma of hypercalcemic type (SCCHT). Familial occurrence of this neoplasm was described previously.

METHODS

We looked for germline SMARCA4 alterations in eight patients with the SCCHT. DNA was extracted from probands' and their relatives' blood. The SMARCA4 coding sequence, previously found altered in all the tumors, was PCR amplified and sequenced in the germline DNA.

RESULTS

Two patients carried a heterozygous germline SMARCA4 alteration: c.3760G > T and c.2352insG, respectively. The analysis of the probands' next of kins revealed that the c.3760G > T mutation was inherited by the proband and her sister from their father, and the sisters' four children also carried the mutation. The proband's sister was diagnosed with a carcinoma of the parotid gland at age 2. A brother of the other proband was tested negative.

CONCLUSIONS

Our study suggests that some women develop the ovarian SCCHT due to the inherited or possibly de novo-occurring germline alterations in the SMARCA4 gene, however, its penetrance appears limited. Nevertheless, because of high aggressiveness of the SCCHT, a molecular diagnostics of the SMARCA4 gene and careful follow-up should be offered to patients with this cancer and their families.

Rhabdoid tumor predisposition syndrome

Rhabdoid tumors (RT), or malignant rhabdoid tumors, are among the most aggressive and lethal forms of human cancer. They can arise in any location in the body but are most commonly observed in the brain, where they are called atypical teratoid/rhabdoid tumors (AT/RT), and in the kidneys, where they are called rhabdoid tumors of the kidney. The vast majority of rhabdoid tumors present with a loss of function in the SMARCB1 gene, also known as INI1, BAF47, and hSNF5, a core member of the SWI/SNF chromatin-remodeling complex. Recently, mutations in a 2nd locus of the SWI/SNF complex, the SMARCA4 gene, also known as BRG1, were found in rhabdoid tumors with retention of SMARCB1 expression. Familial cases may occur in a condition known as rhabdoid tumor predisposition syndrome (RTPS). In RTPS, germline inactivation of 1 allele of a gene occurs. When the mutation occurs in the SMARCB1 gene, the syndrome is called RTPS1, and when the mutation occurs in the SMARCA4 gene it is called RTPS2. Children presenting with RTPS tend to develop tumors at a younger age, but the impact that germline mutation has on survival remains unclear. Adults who carry the mutation tend to develop multiple schwannomas. The diagnosis of RTPS should be considered in patients with RT, especially if they have multiple primary tumors, and/or in individuals with a family history of RT. Because germline mutations result in an increased risk of carriers developing RT, genetic counseling for families with this condition is recommended.

Loss of the tumor suppressor SMARCA4 in small cell carcinoma of the ovary, hypercalcemic type (SCCOHT)

Small cell carcinoma of the ovary, hypercalcemic type (SCCOHT), is a rare and understudied cancer with a dismal prognosis. SCCOHT's infrequency has hindered empirical study of its biology and clinical management. However, we and others have recently identified inactivating mutations in the SWI/SNF chromatin remodeling gene SMARCA4 with concomitant loss of SMARCA4 protein in the majority of SCCOHT tumors.(1-4) Here we summarize these findings and report SMARCA4 status by targeted sequencing and/or immunohistochemistry (IHC) in an additional 12 SCCOHT tumors, 3 matched germlines, and the cell line SCCOHT-1. We also report the identification of a homozygous inactivating mutation in the gene SMARCB1 in one SCCOHT tumor with wild-type SMARCA4, suggesting that SMARCB1 inactivation may also play a role in the pathogenesis of SCCOHT. To date, SMARCA4 mutations and protein loss have been reported in the majority of 69 SCCOHT cases (including 2 cell lines). These data firmly establish SMARCA4 as a tumor suppressor whose loss promotes the development of SCCOHT, setting the stage for rapid advancement in the biological understanding, diagnosis, and treatment of this rare tumor type.

SWI/SNF chromatin remodeling and human malignancies

The SWI/SNF complexes, initially identified in yeast 20 years ago, are a family of multi-subunit complexes that use the energy of adenosine triphosphate (ATP) hydrolysis to remodel nucleosomes. Chromatin remodeling processes mediated by the SWI/SNF complexes are critical to the modulation of gene expression across a variety of cellular processes, including stemness, differentiation, and proliferation. The first evidence of the involvement of these complexes in carcinogenesis was provided by the identification of biallelic, truncating mutations of the SMARCB1 gene in malignant rhabdoid tumors, a highly aggressive childhood cancer. Subsequently, genome-wide sequencing technologies have identified mutations in genes encoding different subunits of the SWI/SNF complexes in a large number of tumors. SWI/SNF mutations, and the subsequent abnormal function of SWI/SNF complexes, are among the most frequent gene alterations in cancer. The mechanisms by which perturbation of the SWI/SNF complexes promote oncogenesis are not fully elucidated; however, alterations of SWI/SNF genes obviously play a major part in cancer development, progression, and/or resistance to therapy.

Next-generation sequencing: a change of paradigm in molecular diagnostic validation

Next-generation sequencing (NGS) is beginning to show its full potential for diagnostic and therapeutic applications. In particular, it is enunciating its capacity to contribute to a molecular taxonomy of cancer, to be used as a standard approach for diagnostic mutation detection, and to open new treatment options that are not exclusively organ-specific. If this is the case, how much validation is necessary and what should be the validation strategy, when bringing NGS into the diagnostic/clinical practice? This validation strategy should address key issues such as: what is the overall extent of the validation? Should essential indicators of test performance such as sensitivity of specificity be calculated for every target or sample type? Should bioinformatic interpretation approaches be validated with the same rigour? What is a competitive clinical turnaround time for a NGS-based test, and when does it become a cost-effective testing proposition? While we address these and other related topics in this commentary, we also suggest that a single set of international guidelines for the validation and use of NGS technology in routine diagnostics may allow us all to make a much more effective use of resources.