Cheng‐Han Lee

GREB1 ‐rearranged uterine tumour shares a common DNA methylation signature with ESR1 ‐rearranged UTROSCT

Background and objectives GREB1 ‐rearranged uterine tumours encompass a group of uterine mesenchymal tumours with varied histologic appearances. The fusion partners to GREB1 include NCOA1‐3, SS18 and NR4A3 . Given that some GREB1 ‐rearranged uterine tumours exhibit histologic features of uterine tumours resembling ovarian sex cord tumour (UTROSCT), there is a general belief that GREB1 ‐rearranged uterine mesenchymal tumours are part of the UTROSCT family. Methods In this study, we applied global DNA methylation and copy number analyses to a series of 10 GREB1‐ rearranged uterine tumours and 21 classic UTROSCTs (7 of which were molecularly confirmed to harbour ESR1::NCOA2/3 fusions). Results We found that GREB1 ‐rearranged uterine tumors show an overlap in their global methylation profiles with UTROSCT, including ESR1::NCOA2/3 positive cases. Together, these tumours form a DNA methylation cluster separate from uterine smooth muscle tumours (leiomyomas and leiomyosarcomas), endometrial stromal sarcomas (low‐grade and high‐grade), embryonal rhabdomyosarcoma and SMARCA4‐deficient uterine sarcomas. However, despite their epigenetic similarity, there were two notable differences. First, GREB1 ‐rearranged uterine tumours as a group displayed a greater degree of genomic complexity with more extensive copy number alterations than conventional UTROSCTs, including those harbouring ESR1::NCOA2/3 . Second, GREB1 ‐rearranged uterine tumours frequently lacked overt sex cord morphology: while all 7 ESR1::NCOA2/3 UTROSCTs demonstrated corded, nested, trabecular and/or tubular/sertoliform patterns, only 1 GREB1 ‐rearranged uterine tumour displayed a prominent trabecular pattern, with the remaining cases showing exclusively or predominantly diffuse/solid growth. Conclusions Overall, our findings confirm that GREB1 ‐rearranged uterine tumours are part of the UTROSCT spectrum, though they frequently exhibit a more diffuse growth pattern and a higher degree of genomic instability.

A 5‐marker immunohistochemical panel of CK17 , MEP1A , PAX8 , SMAD4 , and CDX2 to distinguish ovarian mucinous carcinoma from metastatic pancreatic ductal adenocarcinoma

Aims Metastatic pancreatic adenocarcinoma (PDAC), albeit uncommon, may involve the ovary, and distinction from primary ovarian mucinous tumours (OMT) poses a diagnostic challenge. Our aim was to develop an ancillary immunohistochemical (IHC) panel to aid in diagnosis and to validate the morphological features of metastatic PDAC. Methods and results Six IHC markers (CDX2, CK17, MEP1A, MUC2, PAX8, SMAD4) selected based on a literature review were stained on tissue microarrays containing 256 PDAC, 102 mucinous ovarian carcinomas (MC) and 58 mucinous borderline ovarian tumours (MBOT). Detailed morphological features were reviewed in 16 ovarian metastases from PDAC, 25 MC, and 9 MBOT. We confirmed that tumours with a size less than 13 cm, bilaterality, ovarian surface involvement, low‐power nodularity, infiltrative invasion, pseudomyxoma ovarii despite cystadenoma or borderline areas, and moderate nuclear atypia should raise suspicion for metastatic PDAC and prompt evaluation with the recommended IHC panel. A 5‐marker panel consisting of CK17, MEP1A, PAX8, SMAD4, and CDX2 had an overall accuracy of 91.8% (95% CI 88.8%–94.3%) using recursive partitioning, with the highest weight resting on CK17. CK17 was expressed in 80.9% of PDAC compared to 18.6% of MC and 1.7% of MBOT, respectively. Conclusions This is the first ancillary IHC panel to distinguish between PDAC and OMT with high accuracy. These results inform further studies on diagnostic workflows tailored to the complexity of metastatic presentations of tumours at the ovary.

Infiltrative pattern of invasion is independently associated with shorter survival and desmoplastic stroma markers FAP and THBS2 in mucinous ovarian carcinoma

AimsMucinous ovarian carcinoma (MOC) is a rare ovarian cancer histotype with generally good prognosis when diagnosed at an early stage. However, MOC with the infiltrative pattern of invasion has a worse prognosis, although to date studies have not been large enough to control for covariables. Data on reproducibility of classifying the invasion pattern are limited, as are molecular correlates for infiltrative invasion. We hypothesized that the invasion pattern would be associated with an aberrant tumour microenvironment.Methods and resultsFour subspecialty pathologists assessed interobserver reproducibility of the pattern of invasion in 134 MOC. Immunohistochemistry on fibroblast activation protein (FAP) and THBS2 was performed on 98 cases. Association with survival was tested using Cox regression. The average interobserver agreement for the infiltrative pattern was moderate (kappa 0.60, agreement 86.3%). After reproducibility review, 24/134 MOC (18%) were determined to have the infiltrative pattern and this was associated with a higher risk of death, independent of FIGO stage, grade, and patient age in a time‐dependent manner (hazard ratio [HR] = 10.2, 95% confidence interval [CI] 3.0–34.5). High stromal expression of FAP and THBS2 was more common in infiltrative MOC (FAP: 60%, THBS2: 58%, both P < 0.001) and associated with survival (multivariate HR for FAP: 1.5 [95% CI 1.1–2.1] and THBS2: 1.91 [95% CI 1.1–3.2]).ConclusionsThe pattern of invasion should be included in reporting for MOC due to the strong prognostic implications. We highlight the histological features that should be considered to improve reproducibility. FAP and THBS2 are associated with infiltrative invasion in MOC.

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.

Endometrial neuroendocrine carcinoma and undifferentiated carcinoma are distinct entities with overlap in neuroendocrine marker expression

AimsDedifferentiated endometrial carcinomas (DDECs)/undifferentiated endometrial carcinomas (UDECs) frequently harbour genomic activation of switch/sucrose non‐fermentable (SWI/SNF)‐complex proteins, and can show histological overlap with neuroendocrine carcinoma (NEC). The aim of this study was to compare the extent of the expression of neuroendocrine markers, SWI/SNF proteins and mismatch repair (MMR) proteins in DDEC/UDEC and NEC.Methods and resultsThe extent of expression of synaptophysin, chromogranin, CD56, ARID1A, ARID1B, SMARCA4, SMARCB1 and MMR proteins was evaluated by immunohistochemistry on 44 SWI/SNF‐deficient DDECs/UDECs and 15 NECs. Thirty‐three of 44 (75%) DDECs/UDECs showed expression of at least one neuroendocrine marker, with 18 of 44 (41%) expressing two or more neuroendocrine markers, whereas all 15 NECs showed expression of at least one neuroendocrine marker, with 14 of 15 (93%) expressing two or more neuroendocrine markers. Neuroendocrine marker expression in DDECs/UDECs was typically focal when present, with average extents of 17%, 4% and 8% for synaptophysin, chromogranin and CD56 in the positive cases, respectively, in contrast to 73%, 40% and 62% in the positive NEC cases, respectively. All 15 NECs showed intact expression of SWI/SNF‐complex proteins, except for one that showed isolated loss of ARID1A. Thirty‐eight of 44 DDECs/UDECs were MMR‐abnormal (34 with loss of MLH1 and PMS2, and four with loss of PMS2 alone), whereas all NECs retained MMR protein expression.ConclusionsOur study demonstrates frequent but typically focal neuroendocrine marker expression in SWI/SNF‐deficient DDECs/UDECs, whereas NECs typically express two or more neuroendocrine markers, with diffuse expression of at least one marker. ARID1B, SMARCA4 and SMARCB1 immunohistochemistry can be used to aid in the differentiation between DDEC/UDEC and NEC.

Treatment and outcomes in undifferentiated and dedifferentiated endometrial carcinoma

Undifferentiated and dedifferentiated endometrial carcinoma is a rare type of uterine malignancy. This study assesses disease characteristics, treatment and survival outcomes in patients with undifferentiated and dedifferentiated endometrial carcinoma treated at BC Cancer. All patients diagnosed with undifferentiated and dedifferentiated endometrial carcinoma between 2000 and 2019 at BC Cancer were reviewed centrally. Clinical, pathologic, treatment and outcomes were reviewed retrospectively. The Kaplan-Meier method was used to evaluate overall survival (OS) and disease-free survival (DFS). Multivariable analysis was performed using Cox regression analysis. Fifty-two patients were included, 33% had undifferentiated carcinoma and 67% dedifferentiated carcinoma. Sixty-nine percent of those who had mismatch repair (MMR) testing of their tumor had an abnormal profile. The 5-year DFS was 80% (95% confidence interval [CI]=71%-89%) for stage I/II, 29% (95% CI=28%-40%) for stage III and 10% (95% CI 1%-19%) for stage IV. The 5-year OS was 84% (95% CI=75%-92%) for stage I/II, 38% (95% CI=26%-50%) for stage III and 12% (95% CI=1%-24%) for stage IV. Multivariate analysis showed that receiving adjuvant chemotherapy, adjuvant radiotherapy, lower stage and better Eastern Cooperative Group performance status were associated with improved DFS (p<0.05). Patients with stage I/II undifferentiated and dedifferentiated endometrial carcinoma had excellent survival outcomes, those with stage III/IV had worse outcomes, similar to previously reported. Adjuvant chemotherapy and radiotherapy were associated with improved DFS. MMR testing should be performed for these patients due to the high incidence of abnormal profiles.

CCNE1 and survival of patients with tubo‐ovarian high‐grade serous carcinoma: An Ovarian Tumor Tissue Analysis consortium study

AbstractBackgroundCyclin E1 (CCNE1) is a potential predictive marker and therapeutic target in tubo‐ovarian high‐grade serous carcinoma (HGSC). Smaller studies have revealed unfavorable associations for CCNE1 amplification and CCNE1 overexpression with survival, but to date no large‐scale, histotype‐specific validation has been performed. The hypothesis was that high‐level amplification of CCNE1 and CCNE1 overexpression, as well as a combination of the two, are linked to shorter overall survival in HGSC.MethodsWithin the Ovarian Tumor Tissue Analysis consortium, amplification status and protein level in 3029 HGSC cases and mRNA expression in 2419 samples were investigated.ResultsHigh‐level amplification (&gt;8 copies by chromogenic in situ hybridization) was found in 8.6% of HGSC and overexpression (&gt;60% with at least 5% demonstrating strong intensity by immunohistochemistry) was found in 22.4%. CCNE1 high‐level amplification and overexpression both were linked to shorter overall survival in multivariate survival analysis adjusted for age and stage, with hazard stratification by study (hazard ratio [HR], 1.26; 95% CI, 1.08‐1.47, p = .034, and HR, 1.18; 95% CI, 1.05‐1.32, p = .015, respectively). This was also true for cases with combined high‐level amplification/overexpression (HR, 1.26; 95% CI, 1.09‐1.47, p = .033). CCNE1 mRNA expression was not associated with overall survival (HR, 1.00 per 1‐SD increase; 95% CI, 0.94‐1.06; p = .58). CCNE1 high‐level amplification is mutually exclusive with the presence of germline BRCA1/2 pathogenic variants and shows an inverse association to RB1 loss.ConclusionThis study provides large‐scale validation that CCNE1 high‐level amplification is associated with shorter survival, supporting its utility as a prognostic biomarker in HGSC.

NOTCH Signaling Limits the Response of Low-Grade Serous Ovarian Cancers to MEK Inhibition

Abstract Low-grade serous ovarian cancer (LGSOC) is a rare subtype of epithelial ovarian cancer with high fatality rates in advanced stages due to its chemoresistant properties. LGSOC is characterized by activation of MAPK signaling, and recent clinical trials indicate that the MEK inhibitor (MEKi) trametinib may be a good treatment option for a subset of patients. Understanding MEKi-resistance mechanisms and subsequent identification of rational drug combinations to suppress resistance may greatly improve LGSOC treatment strategies. Both gain-of-function and loss-of-function CRISPR-Cas9 genome-wide libraries were used to screen LGSOC cell lines to identify genes that modulate the response to MEKi. Overexpression of MAML2 and loss of MAP3K1 were identified, both leading to overexpression of the NOTCH target HES1, which has a causal role in this process as its knockdown reversed MEKi resistance. Interestingly, increased HES1 expression was also observed in selected spontaneous trametinib-resistant clones, next to activating MAP2K1 (MEK1) mutations. Subsequent trametinib synthetic lethality screens identified SHOC2 downregulation as being synthetic lethal with MEKis. Targeting SHOC2 with pan-RAF inhibitors (pan-RAFis) in combination with MEKi was effective in parental LGSOC cell lines, in MEKi-resistant derivatives, in primary ascites cultures from patients with LGSOC, and in LGSOC (cell line–derived and patient-derived) xenograft mouse models. We found that the combination of pan-RAFi with MEKi downregulated HES1 levels in trametinib-resistant cells, providing an explanation for the synergy that was observed. Combining MEKis with pan-RAFis may provide a promising treatment strategy for patients with LGSOC, which warrants further clinical validation.

Concurrent RB1 Loss and BRCA Deficiency Predicts Enhanced Immunologic Response and Long-term Survival in Tubo-ovarian High-grade Serous Carcinoma

Abstract Purpose: The purpose of this study was to evaluate RB1 expression and survival across ovarian carcinoma histotypes and how co-occurrence of BRCA1 or BRCA2 (BRCA) alterations and RB1 loss influences survival in tubo-ovarian high-grade serous carcinoma (HGSC). Experimental Design: RB1 protein expression was classified by immunohistochemistry in ovarian carcinomas of 7,436 patients from the Ovarian Tumor Tissue Analysis consortium. We examined RB1 expression and germline BRCA status in a subset of 1,134 HGSC, and related genotype to overall survival (OS), tumor-infiltrating CD8+ lymphocytes, and transcriptomic subtypes. Using CRISPR-Cas9, we deleted RB1 in HGSC cells with and without BRCA1 alterations to model co-loss with treatment response. We performed whole-genome and transcriptome data analyses on 126 patients with primary HGSC to characterize tumors with concurrent BRCA deficiency and RB1 loss. Results: RB1 loss was associated with longer OS in HGSC but with poorer prognosis in endometrioid ovarian carcinoma. Patients with HGSC harboring both RB1 loss and pathogenic germline BRCA variants had superior OS compared with patients with either alteration alone, and their median OS was three times longer than those without pathogenic BRCA variants and retained RB1 expression (9.3 vs. 3.1 years). Enhanced sensitivity to cisplatin and paclitaxel was seen in BRCA1-altered cells with RB1 knockout. Combined RB1 loss and BRCA deficiency correlated with transcriptional markers of enhanced IFN response, cell-cycle deregulation, and reduced epithelial–mesenchymal transition. CD8+ lymphocytes were most prevalent in BRCA-deficient HGSC with co-loss of RB1. Conclusions: Co-occurrence of RB1 loss and BRCA deficiency was associated with exceptionally long survival in patients with HGSC, potentially due to better treatment response and immune stimulation.

Endometrial carcinoma and immune escape: prognostic relevance of HLA class I loss in NSMP subtype

Aims This study aims to define and characterize human leukocyte antigen class I (HLA‐I) expression in a consecutive series of molecularly classified endometrial carcinomas (ECs), and to evaluate its association with clinicopathologic features, spatial cancer–immune phenotypes and patient prognosis, with a focus on the NSMP (no specific molecular profile) subtype. Methods and results HLA‐I expression was assessed by immunohistochemistry on whole tissue sections from 208 ECs, classified into POLE ‐mutated, MMR‐deficient (MMRd), p53‐abnormal (p53abn) and NSMP subtypes. Loss of HLA‐I was identified in 31% of cases and was associated with adverse features including high‐grade, aggressive histotypes, deep myometrial invasion, substantial lymphovascular space invasion (LVSI), extensive tumour necrosis and an ‘excluded’ immune phenotype. While HLA‐I loss showed no significant prognostic impact in POLE , MMRd or p53abn tumours, it significantly correlated with worse disease‐free survival in NSMP tumours ( P  &lt; 0.001). Multivariate analysis confirmed HLA‐I loss as an independent prognostic factor in early‐stage NSMP ECs, in addition to substantial LVSI, presence of lymph node metastases and spatial cancer–immune phenotypes. Integration of HLA‐I status improved the performance of predictive models over time. Conclusions HLA‐I loss defines a biologically aggressive subgroup within NSMP ECs and is associated with adverse clinicopathologic and immune features. Assessment of HLA‐I expression could refine risk stratification in NSMP ECs, a group traditionally lacking robust prognostic markers and may help identify patients who could benefit from intensified clinical surveillance and future immunomodulatory treatment strategies.