Quantitative next-generation sequencing-based analysis indicates progressive accumulation of microsatellite instability between atypical hyperplasia/endometrial intraepithelial neoplasia and paired endometrioid endometrial carcinoma

Endometrial Carcinomas With Subclonal Loss of Mismatch Repair Proteins: A Clinicopathologic and Genomic Study

Subclonal loss of mismatch repair (MMR) proteins has been described in a small subset of endometrial carcinomas (ECs), but the genomic basis for this phenomenon has received limited attention. Herein, we retrospectively evaluated all ECs with MMR immunohistochemistry (n=285) for subclonal loss, and in those (n=6), performed a detailed clinicopathologic and genomic comparison of the MMR-deficient and MMR-proficient components. Three tumors were FIGO stage IA, and one each stage IB, II, and IIIC2. Patterns of subclonal loss were as follows: (1) 3 FIGO grade 1 endometrioid carcinomas with subclonal MLH1/PMS2, MLH1 promoter hypermethylation, and no MMR gene mutations; (2) POLE -mutated FIGO grade 3 endometrioid carcinoma with subclonal PMS2, and PMS2 and MSH6 mutations limited to the MMR-deficient component; (3) dedifferentiated carcinoma with subclonal MSH2/MSH6, as well as complete loss of MLH1/PMS2, MLH1 promoter hypermethylation, and PMS2 and MSH6 mutations in both components; (4) dedifferentiated carcinoma with subclonal MSH6, and somatic and germline MSH6 mutations in both components, but with a higher allele frequency in MMR-deficient foci. Recurrences occurred in 2 patients, one consisted of the MMR-proficient component from a FIGO 1 endometrioid carcinoma, while the other was from the MSH6 -mutated dedifferentiated endometrioid carcinoma. At the last follow-up (median: 44 mo), 4 patients were alive and disease-free and 2 were alive with disease. In summary, subclonal MMR loss reflects subclonal and often complex genomic and epigenetic alterations, which may have therapeutic implications and therefore must be reported when present. In addition, subclonal loss can occur in both POLE -mutated and Lynch syndrome-associated ECs.

Highly Sensitive Microsatellite Instability and Immunohistochemistry Assessment in Endometrial Aspirates as a Tool for Cancer Risk Individualization in Lynch Syndrome

Women with Lynch syndrome (LS) are at increased risk of endometrial cancer (EC), among other tumors, and are characterized by mismatch repair (MMR) deficiency and microsatellite instability (MSI). While risk-reducing gynecological surgeries are effective in decreasing EC incidence, doubts arise regarding the appropriate timing of the surgery. We explored the usefulness of highly-sensitive MSI (hs-MSI) assessment in endometrial aspirates for the individualization of gynecological surveillance in LS carriers. Ninety-three women with LS, 25 sporadic EC patients (9 MMR-proficient and 16 MMR-deficient), and 30 women with benign gynecological disease were included in this study. Hs-MSI was assessed in prospectively collected endometrial aspirates in 67 LS carriers, EC cases, and controls. MMR, PTEN, ARID1A, and PAX2 expression patterns were evaluated in LS samples. Follow-up aspirates from eight LS carriers were also analyzed. Elevated hs-MSI scores were detected in all aspirates from MMR-deficient EC cases (3 LS and 16 sporadic), being negative in aspirates from controls and MMR-proficient EC cases. Positive hs-MSI scores were also detected in all four LS aspirates reported as complex hyperplasia. High hs-MSI was also present in 10 of 49 aspirates (20%) from LS carriers presenting a morphologically normal endometrium, where MMR expression loss was detected in 69% of the samples. Interestingly, the hs-MSI score was positively correlated with MMR-deficient gland density and the presence of MMR-deficient clusters, colocalizing with PTEN and ARID1A expression loss. High hs-MSI scores and clonality were evidenced in two samples collected up to four months before EC diagnosis; hs-MSI scores increased over time in five LS carriers, whereas they decreased in a patient with endometrial hyperplasia after progestin therapy. In LS carriers, elevated hs-MSI scores were detected in aspirates from premalignant and malignant lesions and normal endometrium, correlating with MMR protein loss. Hs-MSI assessment and MMR immunohistochemistry may help individualize EC risk assessment in women with LS.

Clinicopathologic Evaluation and Molecular Profiling of Recurrent Stage IA Endometrial Endometrioid Carcinoma: A Case-control Study

Most low-grade, early-stage endometrial endometrioid carcinomas (EEC) have an excellent prognosis; however, recurrences occur in a small subset with several studies reporting an increase in CTNNB1 exon 3 mutations in this population. Herein we evaluated 10 recurrent low-grade (FIGO 1 or 2), early-stage (FIGO IA) EECs matched to 10 nonrecurrent EECs to further characterize their clinicopathologic features and molecular phenotype. Cases were matched to controls based on size, grade, and depth of invasion. All tumors were evaluated for specific clinicopathologic parameters followed by next-generation sequencing using a 1213 gene panel. Recurrent EECs demonstrated no significant clinicopathologic differences when compared with nonrecurrent EECs, in terms of age, body mass index, pattern of invasion, presence of endometrial atypical hyperplasia/endometrioid intraepithelial neoplasia, associated metaplastic changes, peritumoral lymphocytes, mitoses, and tumor-infiltrating lymphocytes. Both cohorts also showed a similar number of pathogenic mutations, including CTNNB1 exon 3 mutations, as well as tumor mutational burden and microsatellite profiles. Although in this particular study, the lack of correlation between CTNNB1 exon 3 mutation and recurrence might be secondary to a small sample size, it also suggests the presence of other contributing factors. Thus, it helps set the foundation for larger series incorporating whole genome, transcriptome, proteome, and epigenome analyses to answer this clinically important question.

The Role of Immunohistochemistry Markers in Endometrial Cancer with Mismatch Repair Deficiency: A Systematic Review

The objective of this systematic review was to summarize our current knowledge of the role of immunohistochemistry (IHC) markers for identifying mismatch repair-deficient (MMRd) tumors in endometrial cancer (EC). Identification of MMRd tumors, which occur in 13% to 30% of all ECs, has become critical for patients with colorectal and endometrial cancer for therapeutic management, clinical decision making, and prognosis. This review was conducted by two authors applying the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines using the following terms: “immunohistochemistry and microsatellite instability endometrial cancer” or “immunohistochemistry and mismatch repair endometrial cancer” or “immunohistochemistry and mismatch repair deficient endometrial cancer”. Among 596 retrieved studies, 161 fulfilled the inclusion criteria. Articles were classified and presented according to their interest for the diagnosis, prognosis, and theragnostics for patients with MMRd EC. We identified 10, 18, and 96 articles using IHC expression of two, three, or four proteins of the MMR system (MLH1, MSH2, MHS6, and PMS2), respectively. MLH1 promoter methylation was analyzed in 57 articles. Thirty-four articles classified MMRd tumors with IHC markers according to their prognosis in terms of recurrence-free survival (RFS), overall survival (OS), stage, grade, and lymph node invasion. Theragnostics were studied in eight articles underlying the important concentration of PD-L1 in MMRd EC. Even though the role of IHC has been challenged, it represents the most common, robust, and cheapest method for diagnosing MMRd tumors in EC and is a valuable tool for exploring novel biotherapies and treatment modalities.

Uterine PEComas: correlation between melanocytic marker expression and TSC alterations/TFE3 fusions

Uterine PEComas often present a diagnostic challenge as they share morphological and immunohistochemical features with smooth muscle tumors. Herein we evaluated a series of 19 uterine PEComas to compare the degree of melanocytic marker expression with their molecular profile. Patients ranged from 32-77 (median 48) years, with six tumors classified as malignant based on the modified gynecologic-specific prognostic algorithm. All patients with malignant PEComas were alive with disease or dead  of disease at last follow-up, while all those of uncertain malignant potential were alive and well (median follow-up, 47 months).Seventeen of 19 (89%) PEComas harbored either a TSC1 or TSC2 alteration. One of the two remaining tumors showed a TFE3 rearrangement, but the other lacked alterations in all genes evaluated. All showed at least focal (usually strong) positivity for HMB-45, with 15/19 (79%) having >50% expression, while the tumor lacking TSC or TFE3 alterations was strongly positive in 10% of cells. Melan-A and MiTF were each positive in 15/19 (79%) tumors, but staining extent and intensity were much more variable than HMB-45. Five of six (83%) malignant PEComas also harbored alterations in TP53, ATRX, or RB1, findings not identified in any tumors of uncertain malignant potential. One malignant PEComa was microsatellite-unstable/mismatch repair protein-deficient.In summary, TSC alterations/TFE3 fusions and diffuse (>50%) HMB-45 expression are characteristic of uterine PEComas. In morphologically ambiguous mesenchymal neoplasms with myomelanocytic differentiation, especially those with metastatic or recurrent disease, next-generation sequencing is recommended to evaluate for TSC alterations; as such, patients can be eligible for targeted therapy.

Circular RNA hsa_circ_0011324 is involved in endometrial cancer progression and the evolution of its mechanism

Endometrial cancer (EC) is one of the most common gynecological tumors with an increasing incidence. CircRNA plays an essential regulatory role in EC. Our objective was to investigate the potential mechanism of circRNAs derived SPOC Domain Containing 1 (SPOCD1) in EC progression. Seven circRNAs from SPOCD1 were analyzed by circBase and their expression was verified by quantitative real-time polymerase chain reaction. Only the expression of hsa_circ_0011324 was significantly increased in cancer tissues. The cell lines Ishikawa and RL95-2 which interfered with or overexpressed hsa_circ_0011324 were constructed and cell functions were tested. Results revealed hsa_circ_0011324 overexpression promoted cell proliferation, migration, and invasion; while silence of hsa_circ_0011324 had opposite effect on cell functions. RNA22 website and Targetscan website were applied to analyze downstream genes regulated by hsa_circ_0011324. Then, the expression of downstream genes was detected in EC tissues. Results indicated hsa-miR-497/16-5p expression were down-regulated, and mechanistic target of rapamycin kinase (mTOR) was up-regulated in EC. Furthermore, hsa_circ_0011324 regulated mTOR expression and cell functions by affecting hsa-miR-497/16-5p. And the potential mechanism was hsa_circ_0011324 competes with mTOR to directly bind to hsa-miR-497/16-5p. In conclusion, hsa_circ_0011324 could sponge hsa-miR-497/16-5p targeted mTOR to participate in EC progress. Our study may provide a new therapeutic target for EC.

Histopathologic diagnosis of endometrial precancers: Updates and future directions

Early detection of endometrial cancer, especially its precancers, remains a critical and evolving issue in patient management and the quest to decrease mortality due to endometrial cancer. Due to many factors such as specimen fragmentation, the confounding influence of endogenous or exogenous hormones, and variable or overlapping histologic features, identification of bona fide endometrial precancers and their reliable discrimination from benign mimics remains one of the most challenging areas in diagnostic pathology. At the same time, the diagnosis of endometrial precancer, or the presence of suspicious but subdiagnostic features in an endometrial biopsy, can lead to long clinical follow-up with multiple patient visits and serial endometrial sampling, emphasizing the need for accurate diagnosis. Our understanding of endometrial precancers and their diagnosis has improved due to systematic investigations into morphologic criteria, the molecular genetics of endometrial cancer and their precursors, the validation of novel biomarkers and their use in panels, and more recent methods such digital image analysis. Although precancers for both endometrioid and non-endometrioid carcinomas will be reviewed, emphasis will be placed on the former. We review these advances and their relevance to the histopathologic diagnosis of endometrial precancers, and the recently updated 2020 World Health Organization (WHO) Classification of Female Genital Tumors.

Atypical Endometrial Hyperplasia, Low-grade: "Much ADO About Nothing"

Atypical endometrial hyperplasia (AEH) is considered a precursor of endometrioid carcinoma. The 2020 World Health Organization (WHO) classification divides endometrial hyperplasia into 2 categories: hyperplasia without atypia and atypical hyperplasia/endometrioid intraepithelial neoplasia (EIN); however, this classification does not consider the degree of nuclear atypia. We graded nuclear atypia for estimating the risk of finding carcinoma at hysterectomy. Also, we investigated genes involved in endometrial carcinogenesis including mismatch repair (MMR) genes and ARID1A, PIK3CA, PTEN, KRAS, and CTNNB1. We reviewed 79 biopsies of AEH from 79 patients who underwent hysterectomy within a 1-year interval. Intraobserver and interobserver agreement of grading nuclear atypia and the relationship between the grade of nuclear atypia at biopsy and the findings at hysterectomy were evaluated. Immunohistochemistry for MMR status was performed in all cases and targeted sequencing in 11. Using low-grade versus high-grade nuclear atypia, κ values ranged from 0.74 to 0.91 (89% to 96%) and from 0.72 to 0.81 (87% to 91%) for the intraobserver and the interobserver agreement, respectively. The degree of nuclear atypia at biopsy was highly predictive of the findings at hysterectomy (P=1.6×10-15). Of 53 patients with low-grade AEH, none had carcinoma at hysterectomy, whereas 6 (6/26; 23%) with high-grade AEH in the biopsy also had high-grade AEH in the uterus and 16 (16/26; 61%) had FIGO grade 1 carcinoma. MMR deficiency was found in 3 of the 79 patients. None of the genes showed a mutational load significantly associated with the degree of nuclear atypia. In summary, our data show high reproducibility within and between observers for the diagnosis of low-grade and high-grade AEH. Most cases of AEH had low-grade nuclear atypia and neither high-grade AEH nor carcinoma was encountered in the corresponding hysterectomy specimens.

Characterization of Clonal Evolution in Microsatellite Unstable Metastatic Cancers through Multiregional Tumor Sequencing

Microsatellites are short, repetitive segments of DNA, which are dysregulated in mismatch repair-deficient (MMRd) tumors resulting in microsatellite instability (MSI). MSI has been identified in many human cancer types with varying incidence, and microsatellite instability-high (MSI-H) tumors often exhibit increased sensitivity to immune-enhancing therapies such as PD-1/PD-L1 inhibition. Next-generation sequencing (NGS) has permitted advancements in MSI detection, and recent computational advances have enabled characterization of tumor heterogeneity via NGS. However, the evolution and heterogeneity of microsatellite changes in MSI-positive tumors remains poorly described. We determined MSI status in 6 patients using our previously published algorithm, MANTIS, and inferred subclonal composition and phylogeny with Canopy and SuperFreq. We developed a simulated annealing-based method to characterize microsatellite length distributions in specific subclones and assessed the evolution of MSI in the context of tumor heterogeneity. We identified three to eight tumor subclones per patient, and each subclone exhibited MMRd-associated base substitution signatures. We noted that microsatellites tend to shorten over time, and that MMRd fosters heterogeneity by introducing novel mutations throughout the disease course. Some microsatellites are altered among all subclones in a patient, whereas other loci are only altered in particular subclones corresponding to subclonal phylogenetic relationships. Overall, our results indicate that MMRd is a substantial driver of heterogeneity, leading to both MSI and subclonal divergence. IMPLICATIONS: We leveraged subclonal inference to assess clonal evolution based on somatic mutations and microsatellites, which provides insight into MMRd as a dynamic mutagenic process in MSI-H malignancies.

Next-generation sequencing analysis of endometrial screening liquid-based cytology specimens: a comparative study to tissue specimens

Background

Liquid-based cytology (LBC) is now a widely used method for cytologic screening and cancer diagnosis. Since the cells are fixed with alcohol-based fixatives, and the specimens are stored in a liquid condition, LBC specimens are suitable for genetic analyses.

Methods

Here, we established a small cancer gene panel, including 60 genes and 17 microsatellite markers for next-generation sequencing, and applied to residual LBC specimens obtained by endometrial cancer screening to compare with corresponding formalin-fixed paraffin-embedded (FFPE) tissues.

Results

A total of 49 FFPE and LBC specimens (n = 24) were analyzed, revealing characteristic mutations for endometrial cancer, including PTEN, CTNNB1, PIK3CA, and PIK3R1 mutations. Eight cases had higher scores for both tumor mutation burden (TMB) and microsatellite instability (MSI), which agree with defective mismatch repair (MMR) protein expression. Paired endometrial LBC, and biopsied and/or resected FFPE tissues from 7 cases, presented almost identical mutations, TMB, and MSI profiles in all cases.

Conclusion

These findings demonstrate that our ad hoc cancer gene panel enabled the detection of therapeutically actionable gene mutations in endometrial LBC and FFPE specimens. Endometrial cancer LBC specimens offer an alternative and affordable source of molecular testing materials.

Mutational profile of endometrial hyperplasia and risk of progression to endometrioid adenocarcinoma

BACKGROUND

Endometrial hyperplasia is a precursor to endometrioid adenocarcinoma (EMC), the most common uterine cancer. The likelihood of progression to carcinoma may be evaluated by histologic subclassification of endometrial hyperplasia, although these subclasses are subjective and only modestly reproducible among pathologists. Patient care would be improved by a more objective test to predict the risk of cancer progression.

METHODS

Next-generation sequencing was performed on archived endometrial biopsy specimens from a retrospective cohort of women with endometrial hyperplasia. Cases were considered to be either progressing if the patient subsequently developed EMC or resolving if the patient had a subsequent negative tissue sampling or no cancer during medium-term follow-up (32 patients: 15 progressing and 17 resolving). Somatic mutations in endometrial hyperplasia were assessed for enrichment in progressing cases versus resolving cases, with an emphasis on genes commonly mutated in EMC.

RESULTS

Several mutations were more common in progressing hyperplasia than resolving hyperplasia, although significant overlap was observed between progressing and resolving cases. Mutations included those in PTEN, PIK3CA, and FGFR2, genes commonly mutated in EMC. Mutations in ARID1A and MYC were seen only in progressing hyperplasia, although these were uncommon; this limited diagnostic sensitivity. Progressing hyperplasia demonstrated an accumulation of mutations in oncogenic signaling pathways similarly to endometrial carcinoma.

CONCLUSIONS

Because of mutational differences between progressing and nonprogressing hyperplasia, mutational analysis may predict the risk of progression from endometrial hyperplasia to EMC.