Small Cell Carcinoma Of The Ovary, Hypercalcemic Type Research Articles

Small cell carcinoma of the ovary of hypercalcaemic type: a clinicopathological analysis of sixteen cases

Objective: To investigate the clinicopathological, molecular pathological features, and family genetic pedigree of small cell carcinoma of the ovary, hypercalcemic type (SCCOHT). Methods: A total of 16 cases of SCCOHT diagnosed in Obstetrics and Gynecology Hospital of Fudan University from January 2013 to January 2023 were collected. The clinicopathologic features, SMARCA4/2/B1 protein expression, outcomes and SMARCA4 gene detection were reported. A follow-up study was also carried out. Results: The average age at diagnosis was 28.7 years (range 17-38 years). The preoperative calcium level was evaluated in 3 of 6 patients. The tumor was unilateral in all 16 cases, ranged from 8 to 26 cm (average 15.8 cm) in the greatest dimension. Extraovarian spread was present in 7 cases. In 10 cases, the tumors were initially misinterpreted as other ovarian neoplasms. BRG1 and BRM expression by immunohistochemistry were all lost in detected cases, while INI1 exhibited retained nuclear expression. All BRM-negative SCCOHTs also lacked BRG1 protein,but retained INI1 expression. SCCOHTs were only focally positive for EMA, CKpan, Calretinin, SALL4, and diffusely positive for WT1. Two of nine cases exhibited mutation-type p53 immunoreactivity. Ki-67 index was 58% on an average. ER, PR, FOXL2, α-inhibin, chromogranin A and LCA were negative in all the cases. SMARCA4 sequencing was available in 8 cases of SCCOHT, which revealed a germline SMARCA4 mutation in one patient, and others carried somatic mutation. Furthermore, two daughters, mother and an aunt of a patient with germline mutation were reported to be SMARCA4 mutation carriers. Follow-up was available for 15 patients, and the 6-month, 1-year and 2-year survival rate was 65.8%, 45.1%, and 22.6%, respectively. For patients in FIGO stages Ⅱ+Ⅲ, 6-month, 1-year survival rate was 53.6% and 35.7% respectively, compared to 80% (6-month) and 60% (1-year) in patients of staged I (P=0.358). Conclusions: With dismal prognosis of SCCOHT, accurate diagnosis is necessary. The typical age distribution, a panel of various staining results, especially concomitant loss of BRG1 and BRM may be of diagnostic aid and can be used to distinguish SCCOHT from its histological mimics. After the diagnosis of SCCOHT, genetic testing and genetic counseling are recommended.

Clinicopathological Characteristics of Small Cell Carcinoma of the Ovary, Hypercalcemic Type – a case Series

Abstract Introduction/Objective Small cell carcinoma of the ovary hypercalcemic type (SCCOHT) is a rare (<0.01%) and aggressive ovarian tumor primarily affecting young women (median of approximately 24 years), characterized by rapid growth, early metastasis, and association with hypercalcemia in two-thirds of cases. The diagnosis of SCCOHT is challenging due to its rarity and lack of specific clinical symptoms or biomarkers. Our study aims to delineate the clinicopathologic characteristics of SCCOHT based on our case series and add to the existing knowledge. Methods/Case Report A retrospective review of University of Pennsylvania Health system pathology database was conducted from 2012 to 2024. Our study identified four patients diagnosed with SCCOHT. Clinical information and histopathologic characteristics were reviewed. Results (if a Case Study enter NA) Among the four patients identified, the median age was 24 years, with a median tumor size of 14.5 cm, and all patients presented with weight loss, abdomen bloating, and elevated CA125 levels. Notably, two patients exhibited hypercalcemia, while one initially presented with normal calcium levels but developed hypercalcemia during disease recurrence. One patient maintained normal calcium levels throughout. Surgical intervention involved bilateral salpingo-oophorectomy in all cases, with pathological staging revealing two patients at pT1a, one at pT1c, and one at pT3c. Histopathological analysis consistently revealed similar morphology, including solid and cystic necrotic neoplasms with diffuse growth or nests/cords of undifferentiated small cells, which displaying vesicular chromatin and prominent nucleoli. Immunohistochemical staining demonstrated loss of BRG1 (SMARCA4) expression in two patients and diffuse positivity for WT1 in all patietns, while negative for cytokeratin, germ cell markers, and melanocytic markers. Genetic test revealed SMARCA4 mutation (p.E 717*, c.3169-1G>A) in one patient. Conclusion Small cell carcinoma of the ovary, hypercalcemic type, presents a diagnostic and therapeutic challenge due to its rarity and aggressive nature. Adequate treatment options are currently limited, highlighting the critical need for further research and development of targeted therapies in SCCOHT. Testing for mutations in the SMARCA4 gene is essential for accurate diagnosis of SCCOHT and may uncover new avenues for treatment and management strategies.

Using cancer phenotype sex-specificity to enable unbiased penetrance estimation of SMARCA4 pathogenic variants for small cell carcinoma of the ovary, hypercalcemic type (SCCOHT)

PurposeSmall cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is an extremely rare, highly aggressive cancer (mean age of onset, 24 years). Nearly all cases are associated with somatic or germline pathogenic variants (GPVs) in SMARCA4. Early bilateral oophorectomy is recommended for unaffected females with a SMARCA4 GPV. However, the penetrance of SMARCA4 GPVs for SCCOHT is highly uncertain and subject to ascertainment bias. MethodsLeveraging the early-onset, sex-specific, highly morbid nature of SCCOHT, we hypothesized that the penetrance for SCCOHT could be quantified from the deficit in SMARCA4 GPVs in females compared with males in UK Biobank, a population cohort for which recruitment was restricted to those age 40 to 69. We also analyzed pedigrees ascertained internationally by the Montreal-based SCCOHT-SMARCA4 Registry. ResultsWe observed SMARCA4 GPVs in 8/210,182 (0.0038%) female and 18/179,210 (0.0100%) male participants in UK Biobank (P = .028), representing a male:female odds ratio of 2.64 (95%CI 1.09-7.02), implying a penetrance of 62% for SCCOHT (given the absence of other SMARCA4-related female-specific early morbid diseases). A deficit of GPVs in females in UK Biobank was also demonstrated for BRCA1 and TP53. ConclusionOur findings support bilateral oophorectomy in early adulthood as a rational choice for at-risk females with SMARCA4 GPVs.

Aberrant SWI/SNF Complex Members Are Predominant in Rare Ovarian Malignancies-Therapeutic Vulnerabilities in Treatment-Resistant Subtypes.

SWI/SNF (SWItch/Sucrose Non-Fermentable) is the most frequently mutated chromatin-remodelling complex in human malignancy, with over 20% of tumours having a mutation in a SWI/SNF complex member. Mutations in specific SWI/SNF complex members are characteristic of rare chemoresistant ovarian cancer histopathological subtypes. Somatic mutations in ARID1A, encoding one of the mutually exclusive DNA-binding subunits of SWI/SNF, occur in 42-67% of ovarian clear cell carcinomas (OCCC). The concomitant somatic or germline mutation and epigenetic silencing of the mutually exclusive ATPase subunits SMARCA4 and SMARCA2, respectively, occurs in Small cell carcinoma of the ovary, hypercalcaemic type (SCCOHT), with SMARCA4 mutation reported in 69-100% of SCCOHT cases and SMARCA2 silencing seen 86-100% of the time. Somatic ARID1A mutations also occur in endometrioid ovarian cancer (EnOC), as well as in the chronic benign condition endometriosis, possibly as precursors to the development of the endometriosis-associated cancers OCCC and EnOC. Mutation of the ARID1A paralogue ARID1B can also occur in both OCCC and SCCOHT. Mutations in other SWI/SNF complex members, including SMARCA2, SMARCB1 and SMARCC1, occur rarely in either OCCC or SCCOHT. Abrogated SWI/SNF raises opportunities for pharmacological inhibition, including the use of DNA damage repair inhibitors, kinase and epigenetic inhibitors, as well as immune checkpoint blockade.

MR imaging diagnosis of small-cell carcinoma of the ovary, hypercalcemic type: A case report and literature review.

Small-cell carcinoma of the ovary, hypercalcemic type (SCCOHT), is a rare and aggressive gynecological tumor. We retrospectively analyzed the clinical manifestations and imaging findings of this patient and analyzed the relevant literature, with the aim of improving the ability of radiologists to differentiate SCCOHT from other ovarian tumors. We report a case of 36-year-old woman who was diagnosed with SCCOHT. MRI suggested a malignant tumor of the left ovary. The immunohistochemical markers shows SMARCA4 negativity. Notably, hypercalcemia was not detected. Microscopically, it was consistent with the large-cell variants. Despite its rarity, SCCOHT should still be considered in the differential diagnosis of ovarian malignancies. When a young female patient presents with a large unilateral tumor on MRI with a predominant solid component and significant enhancement on the contrast enhanced scans, along with hypercalcemia, SCCOHT should be considered.

Hypercalcemic Ovarian Carcinoma (Small Cell Carcinoma of the Ovary, Hypercalcemic Type (SCCOHT)): A Case Series and Review of Literature of a Rare Malignancy.

Small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is one of the rare and aggressive cancers occurring mainly in adolescents and young women. It accounts for less than 0.01% of all ovarian malignancies, with around 500 cases reported to date in the medical literature. It has been postulated that these cases could be due to genetic alterations, and in 2014, studies discovered that SCCOHT is characterized by both germline and somatic deleterious mutations in SMARCA4. In this case series, we report two cases diagnosed with carcinoma ovary and found to be having mutations in SMARCA4. The patients in this case series were relatively young and both had germline SMARCA4 mutation. The first patient had FIGO stage IV disease and the second patient had FIGO stage III disease. The first patient started with paclitaxel plus carboplatin and the second patient started with gemcitabine plus docetaxel. One patient succumbed to disease within 1year and another patient is alive at present with progression of disease. SCCOHT is very aggressive and needs diagnosis and treatment at an early stage. Early diagnosis and proper treatment may prolong survival. There is a need for evaluation of the possible role of targeted systemic therapeutic options as the conventional regimens are rarely sufficient.

Small Cell Carcinoma of the Ovary, Hypercalcemic Type (SCCOHT) - Current State of knowledge

Small Cell Carcinoma of the Ovary, Hypercalcemic Type (SCCOHT) - Current State of knowledge

Clinical characteristics and status of treatment of small-cell carcinoma of the ovary, hypercalcemic type in the Chinese population: a meta-analysis.

This study aimed to comprehensively analyze the clinical characteristics and treatment status of Chinese small cell carcinoma of the ovary hypercalcemic type (SCCOHT) patients, providing insights into this unique population and comparing findings with international literature. Through a meta-analysis, we collected data from published case reports and records from the Obstetrics & Gynecology Hospital of Fudan University. Demographic information, clinical presentations, tumor attributes, treatment modalities, and survival outcomes were extracted and examined alongside relevant global studies. The analysis encompassed 80 Chinese SCCOHT patients, of which 62 from 33 previously reported literatures, and the other 18 were from Obstetrics & Gynecology Hospital of Fudan University. In 62 cases with stage information, A total of 25 tumors were International Federation of Gynecology and Obstetrics stage I, 3 were stage II, 19 were stage III, and 15 were stage IV. Most patients received surgery and chemotherapy, but regimens were varied. Median follow-up was 10 months (range=4-120). Elevated carbohydrate antigen 125 and serum calcium levels were consistent findings. Recurrence rates were notable, especially among stage I patients. Platinum-based chemotherapy, paclitaxel and carboplatin (n=11, 13.4%), constituted common treatment regimens. This study observed demographic and clinical similarities with international datasets. And the findings emphasize the urgency for innovative therapeutic approaches to improve outcomes in SCCOHT patients. Continued research efforts are essential to enhance the knowledge surrounding this rare malignancy and to optimize its clinical management.

Dedifferentiated and Undifferentiated Ovarian Carcinoma: An Aggressive and Molecularly Distinct Ovarian Tumor Characterized by Frequent SWI/SNF Complex Inactivation

Dedifferentiated and undifferentiated ovarian carcinomas (DDOC/UDOC) are rare neoplasms defined by the presence of an undifferentiated carcinoma. In this study, we detailed the clinical, pathological, immunohistochemical, and molecular features of a series of DDOC/UDOC. We collected a multi-institutional cohort of 23 DDOC/UDOC and performed immunohistochemistry for core switch/sucrose nonfermentable (SWI/SNF) complex proteins (ARID1A, ARID1B, SMARCA4, and SMARCB1), mismatch repair (MMR) proteins, and p53. Array-based genome-wide DNA methylation and copy number variation analyses were performed on a subset of cases with comparison made to a previously reported cohort of undifferentiated endometrial carcinoma (UDEC), small cell carcinoma of the ovary, hypercalcemic type (SCCOHT), and tubo-ovarian high-grade serous carcinoma (HGSC). The age of all 23 patients with DDOC/UDOC ranged between 22 and 71 years (with an average age of 50 years), and a majority of them presented with extraovarian disease (16/23). Clinical follow-up was available for 19 patients. Except for 2 patients, the remaining 17 patients died from disease, with rapid disease progression resulting in mortality within a year in stage II–IV settings (median disease-specific survival of 3 months). Eighteen of 22 cases with interpretable immunohistochemistry results showed loss of expression of core SWI/SNF protein(s) that are expected to result in SWI/SNF complex inactivation as 10 exhibited coloss of ARID1A and ARID1B, 7 loss of SMARCA4, and 1 loss of SMARCB1. Six of 23 cases were MMR-deficient. Two of 20 cases exhibited mutation-type p53 immunoreactivity. Methylation profiles showed coclustering of DDOC/UDOC with UDEC, which collectively were distinct from SCCOHT and HGSC. However, DDOC/UDOC showed an intermediate degree of copy number variation, which was slightly greater, compared with SCCOHT but much less compared with HGSC. Overall, DDOC/UDOC, like its endometrial counterpart, is highly aggressive and is characterized by frequent inactivation of core SWI/SNF complex proteins and MMR deficiency. Its molecular profile overlaps with UDEC while being distinct from SCCOHT and HGSC.

Establishment and characterization of a novel cell line (SCCOHT-CH-1) and PDX models derived from Chinese patients of small cell ovarian carcinoma of the hypercalcemic type

Small cell carcinoma of the ovary hypercalcemic type (SCCOHT) is a rare and aggressive malignancy that poses a significant clinical challenge due to its grim prognosis. Unfortunately, only three SCCOHT cell lines are currently available for scientific research. In this study, we have successfully established a novel SCCOHT cell line from a recurrent lesion of a SCCOHT patient, named SCCOHT-CH-1. We comprehensively characterized the novel cell line by employing techniques such as morphological observation, CCK-8 assay, Transwell assay, clone formation assay, short tandem repeat sequence (STR) analysis, karyotype analysis, immunohistochemical staining, western blot assay, and xenograft tumor formation assay. SCCOHT-CH-1 cells were small circular and had a unique STR profile. The population-doubling time of SCCOHT-CH-1 was 33.02 h. The cell line showed potential migratory and invasive ability. Compared with another SCCOHT cell line COV434, SCCOHT-CH-1 exhibited higher expression of AKT, VIM, and CCND1. At the same time, SCCOHT-CH-1 has the ability of tumorigenesis in vivo. We also successfully constructed three patient-derived xenograft (PDX) models of SCCOHT, which were pathologically diagnosed to be consistent with the primary tumor, accompanied by loss of SAMRCA4 protein expression. The establishment of SCCOHT-CH-1 cell line and PDX models from Chinese people represent a pivotal step toward unraveling the molecular mechanism of SCCOHT and fostering the development of targeted interventions to tackle this challenging malignancy.

Small Cell Carcinoma of the Ovary, Hypercalcemic Type (SCCOHT): Patient Characteristics, Treatment, and Outcome-A Systematic Review.

Small-cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is a rare aggressive ovarian malignancy mainly affecting children, adolescents, and young adults. Since the discovery of mutations in the SMARCA4 gene in 2014, SCCOHT has become the subject of extensive investigation. However, international uniform treatment guidelines for SCCOHT are lacking and the outcome remains poor. The aim of this systematic review is to generate an overview of all reported patients with SCCOHT from 1990 onwards, describing the clinical presentation, genetic characteristics, treatment, and outcome. A systematic search was performed in the databases Embase, Medline, Web of Science, and Cochrane for studies that focus on SCCOHT. Patient characteristics and treatment data were extracted from the included studies. Survival was estimated using Kaplan-Meier's methodology. To assess the difference between survival, the log-rank test was used. To quantify the effect of the FIGO stage, the Cox proportional hazard regression model was estimated. The chi-squared test was used to study the association between the FIGO stage and the surgical procedures. Sixty-seven studies describing a total of 306 patients were included. The median patient age was 25 years (range 1-60 years). The patients mostly presented with non-specific symptoms such as abdominal pain and sometimes showed hypercalcemia and elevated CA-125. A great diversity in the diagnostic work-up and therapeutic approaches was reported. The chemotherapy regimens were very diverse, all containing a platinum-based (cisplatin or carboplatin) backbone. Survival was strongly associated with the FIGO stage at diagnosis. SCCOHT is a rare and aggressive ovarian cancer, with a poor prognosis, and information on adequate treatment for this cancer is lacking. The testing of mutations in SMARCA4 is crucial for an accurate diagnosis and may lead to new treatment options. Harmonization and international collaboration to obtain high-quality data on diagnostic investigations, treatment, and outcome are warranted to be able to develop international treatment guidelines to improve the survival chances of young women with SCCOHT.

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

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. 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. 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. 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. 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.

Abstract 2577: Pre-cancerous ovarian cells harboring a familial SMARCA4 mutation acquire in vitro phenotypes associated with transformation in SSCOHT

Abstract Introduction: Small Cell Carcinoma of the Ovary, Hypercalcemic Type (SCCOHT) is an extremely rare but deadly ovarian cancer associated with mutations in the SMARCA4 gene. Using a unique population of ovarian cells derived from a familial carrier of an SCCOHT-associated SMARCA4 mutation, we sought to determine if non-cancerous cells would spontaneously transform during in vitro culture, thereby providing a model system for studying formation of SCCOHT. Methods: Ovarian cells derived from a familial carrier of a SMARCA4 mutation (P590, SMARCA4. c.3081+1G>T) were serially passaged in vitro and interrogated for acquisition of phenotypes consistent with cellular transformation. Loss of contact-dependent inhibition was interrogated with focus-forming assays in confluent monolayers. The ability of cells to escape anoikis and grow independently as spheroids was tested in attachment-free growth conditions using both single and aggregate spheroid growth assays. Senescence-associated β-galactosidase (SA-β-gal), cellular necrosis, and cellular apoptosis was also measured. All experiments were conducted in parallel with an age-matched cell population derived from a benign ovarian surgery (P583). In experiments to determine if these differences could be attributed to loss of functional SMARCA4, non-mutant P583 cells were cultured in the presence of the SWI/SNF inhibitor BRM014 and interrogated in focus-forming and attachment-free growth assays. Results: P590 cells passaged over 12 twelve times (approx. 40 cell divisions) continued to proliferate in culture. In contrast, non-mutant P583 cells failed to grow beyond 11-12 passages. With prolonged culture, P590 cells lost expression of SMARCA4 protein, while P583 cells retained SMARCA4 expression. P590 cells grown to confluency spontaneously formed foci of multicellular aggregates, while P583 cells did not. In attachment-free culture conditions, P590 cells readily formed spheroids from both early-passage and late-passage cells. In contrast, P583 formed small spheroids that failed to expand in culture. Surprisingly, both P590 and P583 cells displayed elevated SA-β-gal staining, with neither cell populations showing elevated necrosis or apoptosis markers. Treating P583 cells with BRM014 increased focus formation and spheroid growth similar to that of mutant cells. Conclusions: SCCOHT is extremely rare, with very few representative samples useful for developing early-stage markers or improved therapeutics. Long-term culture of ovarian cells harboring inactivated forms of SMARCA4 result in the acquisition of several phenotypes consistent with early stages of cellular transformation. Our data suggest that mutating or inactivating SMARCA4 in non-transformed ovarian cells may be a way to create novel research tools for studying formation of SCCOHT. This work was supported by DoD award W81XWH-21-1-0512 Citation Format: Sonali Joshi, Shawn Campbell, Yukie Bean, Tanja Pejovic, Adam Krieg. Pre-cancerous ovarian cells harboring a familial SMARCA4 mutation acquire in vitro phenotypes associated with transformation in SSCOHT [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2577.

Abstract 3277: SWI/SNF inactivation vulnerability

Abstract Genetic inactivation in specific SWI/SNF complex members induce sensitivity to the inhibition of KDM6A/UTX and KDM6B/JMJD3 in cancer. Despite the genetic inactivation of the tumor suppressor SMARCA4 is frequently found in cancer, there are no therapies that effectively target SMARCA4-deficient tumors. In our previous work, we reported that unlike the cells with activated MYC oncogene, cells with SMARCA4 inactivation are refractory to the histone deacetylase inhibitor, SAHA, leading to the aberrant accumulation of H3K27me3. In this context, SMARCA4 deficient cells showed an impaired transactivation and significantly reduced levels of the histone H3K27me3 specific demethylases, KDM6A/UTX and KDM6B/JMJD3, and their inhibition compromises cell viability specifically in SMARCA4 mutant cells. Furthermore, the in vivo administration of KDM6s inhibitor (GSK-J4) to mice orthotopically implanted with SMARCA4 mutant lung cancer cell lines or primary tumors of small cell carcinoma of the ovary, hypercalcemic type (SCCOHT), showed a strong anti-tumor effect, highlighting the vulnerability of the SMARCA4 deficient tumors to KDM6s inhibition as a biomarker that could be exploited for treating SMARCA4-mutant cancer patients (Romero OA, Vilarrubi A, et al. SMARCA4 deficient tumors are vulnerable to KDM6A/UTX and KDM6B/JMJD3 blockade. Nat Comm 12, 4319, 2021). Considering our previous observations, and due to the biological role of SMARCA4 as a core component of the SWI/SNF chromatin-remodeling complex, whose members are genetically inactivated in approximately 20% of all human cancers, we wanted to determine the potential response to KDM6s inhibitors in a context of genetic alterations in genes encoding for the other subunits of this remodeling complex. For this propose, we have integrated state of the art technology like genome-wide chromatin modification analysis (ChIP-seq) and transcriptome analysis (RNA-seq), using human cancer cell lines and preclinical models of different cancer types with genetic inactivation at different SWI/SNF-complex members, including mouse models such as orthoxenografts, to design a personalized epigenetic treatment based on the genetic background. Our results showed that, like SMARCA4 deficient cells, specific mutations at some, but not all, SWI/SNF components induce refractoriness to SAHA, aberrant increase of H3K27me3 mark and sensitizes cancer cells to KDM6 inhibitor accompanied with significantly reduced levels of KDM6A and KDM6B expression. These results suggest a strong functional relationship between KDM6A/6B activity and the SWI/SNF-complex, in the control of gene expression and cancer development. These results will be of great value for the stratification of tumors according to their genetic background for tailored treatments, opening the possibility to use SWI/SNF mutations as potential biomarkers for personalized epigenetic-based therapeutics in cancer. Citation Format: Andrea Vilarrubi, Fernando Setien, Eva Pros, Pedro P. Medina, Antonio Gomez, Alberto Villanueva, Octavio A. Romero, Montse Sanchez-Cespedes. SWI/SNF inactivation vulnerability [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3277.

The value of SOX2 in the differential diagnosis of SMARCA4 (BRG1)-deficient uterine neoplasms

SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily A, member 4 (SMARCA4/BRG1)-deficient undifferentiated uterine sarcoma (SDUS) is a recently described uterine sarcoma. It is characterized by predominantly rhabdoid or large epithelioid cells with abundant cytoplasm and varying components of small and spindle cells, resembling the 'large cell variant' of small cell carcinoma of the ovary, hypercalcemic type (SCCOHT). In addition, SMARCA4-inactivating mutations have been described as the driver mutations in SDUS. However, undifferentiated endometrial carcinoma (UDEC) and dedifferentiated endometrial carcinoma(DDEC) may show some clinical and morphological overlaps with SDUS, and about 20% of reported UDEC/DDEC cases also have loss expression of SMARCA4. SDUS is a very aggressive disease and universally lethal in all reported cases. Differentiating SDUS from UDEC/DDEC is relevant for the prognosis, pathogenesis, and possible targeted therapies for the disease. In this study, we compared the clinical, morphological, immunohistochemical, and molecular characteristics of 10 tumors including 2 SDUS, 2 SCCOHT, 1 uterine carcinoma with neuroendocrine differentiation (UDEC?), and 5 UDEC/DDEC. All 5 UDEC/DDEC cases showed strong and diffuse nuclear positivity for SOX2, while all SCCOHT and SDUS cases were completely negative. We concluded that SOX2 could be a useful marker for the differential diagnosis between SDUS and UDEC/DDEC.

Multi-modality therapies for advanced small cell carcinoma of the ovary, hypercalcemic type (SCCOHT): three case reports and literature review

Background: Small-cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is a rare but highly undifferentiated, aggressive malignancy that primarily affects young women. Most SCCOHT patients present with advanced disease and have a very poor prognosis. Although several therapeutic regimens have been proposed, there is no consensus on the optimal treatment strategy. Case: Herein, we describe three cases of advanced-stage SCCOHT aged from16 to 36 treated with cytoreductive surgery and chemotherapy with or without immune checkpoint blockade treatment. With different strategy, the patients showed utterly different outcomes. Conclusion: The cases highlight the importance of prompt diagnosis as well as early, aggressive, and combined modality treatment of SCCOHT. We believe that improved therapies could result in more young patients surviving SCCOHT.

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 (ATRTs) and extracranial rhabdoid tumours (ECRTs), 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 hypercalcaemic 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, Cyrta 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. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

SMARCA4 deficient tumours are vulnerable to KDM6A/UTX and KDM6B/JMJD3 blockade

Despite the genetic inactivation of SMARCA4, a core component of the SWI/SNF-complex commonly found in cancer, there are no therapies that effectively target SMARCA4-deficient tumours. Here, we show that, unlike the cells with activated MYC oncogene, cells with SMARCA4 inactivation are refractory to the histone deacetylase inhibitor, SAHA, leading to the aberrant accumulation of H3K27me3. SMARCA4-mutant cells also show an impaired transactivation and significantly reduced levels of the histone demethylases KDM6A/UTX and KDM6B/JMJD3, and a strong dependency on these histone demethylases, so that its inhibition compromises cell viability. Administering the KDM6 inhibitor GSK-J4 to mice orthotopically implanted with SMARCA4-mutant lung cancer cells or primary small cell carcinoma of the ovary, hypercalcaemic type (SCCOHT), had strong anti-tumour effects. In this work we highlight the vulnerability of KDM6 inhibitors as a characteristic that could be exploited for treating SMARCA4-mutant cancer patients.

Atypical teratoid/rhabdoid tumors (ATRTs) with SMARCA4 mutation are molecularly distinct from SMARCB1-deficient cases

Atypical teratoid/rhabdoid tumors (ATRTs) are very aggressive childhood malignancies of the central nervous system. The underlying genetic cause are inactivating bi-allelic mutations in SMARCB1 or (rarely) in SMARCA4. ATRT-SMARCA4 have been associated with a higher frequency of germline mutations, younger age, and an inferior prognosis in comparison to SMARCB1 mutated cases. Based on their DNA methylation profiles and transcriptomics, SMARCB1 mutated ATRTs have been divided into three distinct molecular subgroups: ATRT-TYR, ATRT-SHH, and ATRT-MYC. These subgroups differ in terms of age at diagnosis, tumor location, type of SMARCB1 alterations, and overall survival. ATRT-SMARCA4 are, however, less well understood, and it remains unknown, whether they belong to one of the described ATRT subgroups. Here, we examined 14 ATRT-SMARCA4 by global DNA methylation analyses. We show that they form a separate group segregating from SMARCB1 mutated ATRTs and from other SMARCA4-deficient tumors like small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) or SMARCA4 mutated extra-cranial malignant rhabdoid tumors. In contrast, medulloblastoma (MB) samples with heterozygous SMARCA4 mutations do not group separately, but with established MB subgroups. RNA sequencing of ATRT-SMARCA4 confirmed the clustering results based on DNA methylation profiling and displayed an absence of typical signature genes upregulated in SMARCB1 deleted ATRT. In summary, our results suggest that, in line with previous clinical observations, ATRT-SMARCA4 should be regarded as a distinct molecular subgroup.

Re-assigning the histologic identities of COV434 and TOV-112D ovarian cancer cell lines

ObjectiveThe development of effective cancer treatments depends on the availability of cell lines that faithfully recapitulate the cancer in question. This study definitively re-assigns the histologic identities of two ovarian cancer cell lines, COV434 (originally described as a granulosa cell tumour) and TOV-112D (originally described as grade 3 endometrioid carcinoma), both of which were recently suggested to represent small cell carcinoma of the ovary, hypercalcemic type (SCCOHT), based on their shared gene expression profiles and sensitivity to EZH2 inhibitors. MethodsFor COV434 and TOV-112D, we re-reviewed the original pathology slides and obtained clinical follow-up on the patients, when available, and performed immunohistochemistry for SMARCA4, SMARCA2 and additional diagnostic markers on the original formalin-fixed, paraffin-embedded (FFPE) clinical material, when available. For COV434, we further performed whole exome sequencing and validated SMARCA4 mutations by Sanger sequencing. We studied the growth of the cell lines at baseline and upon re-expression of SMARCA4 in vitro for both cell lines and evaluated the serum calcium levels in vivo upon injection into immunodeficient mice for COV434 cells. ResultsThe available morphological, immunohistochemical, genetic, and clinical features indicate COV434 is derived from SCCOHT, and TOV-112D is a dedifferentiated carcinoma. Transplantation of COV434 into mice leads to increased serum calcium level. Re-expression of SMARCA4 in either COV434 and TOV-112D cells suppressed their growth dramatically. ConclusionsCOV434 represents a bona fide SCCOHT cell line. TOV-112D is a dedifferentiated ovarian carcinoma cell line.