Isolated Loss of PMS2 Immunohistochemical Expression is Frequently Caused by Heterogenous MLH1 Promoter Hypermethylation in Lynch Syndrome Screening for Endometrial Cancer Patients

Immune checkpoint markers and tumour mutation burden in Wilms tumour: a study of 59 cases

Wilms tumour (WT) is the most common renal tumour in children, and studies of immune checkpoint inhibitors (ICIs) treatment and markers are limited in number. In this study we investigated the ICIs' related immune landscape by examining the expression of PD-L1, PD-1, CD8 and DNA mismatch repair (MMR) proteins by immunohistochemistry (IHC), tumour mutation burden (TMB), and correlations with histology and clinical outcome. Positive PD-L1 (SP263) expression was defined as modified combined positive score (CPS) ≥1. A total of 59 WTs (from 2000 to 2017), including eight (14.0%) with anaplasia, from 46 patients were analysed (45 primary and 14 metastatic). Thirteen WTs (13/59, 22%) were positive for PD-L1 (8 primary, 5 metastatic; CPS 1.11-3.42). Positive PD-L1 expression was associated with diffuse anaplasia (p<0.05) and significantly shorter progression-free survival (p<0.05) among WTs with favourable histology (n=39). CD8+ lymphocytes were present in all analysed WTs. A subset of CD8+ cells co-expressed PD-1, which was associated with favourable histology and treatment. MMR IHC stains identified two (2/18, 11%) WTs with isolated PMS2 loss. All six WTs analysed for TMB showed low mutation burden. We found CD8+ lymphocytes in all analysed WTs and identified a fraction of WT (17.8% of primary and 35.8% of metastatic) with positive PD-L1 CPS, suggesting potential response to ICIs in some patients.

A comparative analysis of MMR immunohistochemistry panels: Evaluating the utility of four-protein versus two-protein panels in endometrial cancer patients

AIMS

This study aimed to assess the accuracy of a two-protein panel for mismatch repair (MMR) immunohistochemistry (IHC) compared to a four-protein panel in a cohort of endometrial cancer patients.

METHODS

The study included patients diagnosed with endometrial cancer between January 2018 and December 2023 with patients underwent MMR IHC staining for the four-protein panel (MSH2, MSH6, MLH1, and PMS2) serving as the reference standard. Various combinations of two proteins were examined and evaluated for their accuracy against the four-protein panel. Sensitivity, negative predictive value (NPV), and negative likelihood ratio were calculated for each combination. McNemar's test was performed to assess discordance, and receiver operating characteristic (ROC) curves were generated to evaluate diagnostic accuracy.

RESULTS

Of 593 patients, MMR deficiency defined as at least one protein loss was observed in 146 patients (24.62%). When compared with four-protein panel, the highest sensitivity was observed with the MSH6/PMS2 combination (99.32%), followed sequentially by MSH6/MLH1 (97.26%), MSH2/PMS2 (93.15%), MSH2/MLH1 (91.10%), MLH1/PMS2 (79.45%), and MSH2/MSH6 (21.92%). The MSH6/PMS2 combination also demonstrated the best NPV of 99.78% and negative likelihood ratio of 0.01, while MSH6/MLH1 showed satisfactory NPV of 99.11% and negative likelihood ratio of 0.03. McNemar's test revealed no statistical difference between the four-protein panel and the MSH6/PMS2 panel (p = 1.000), and the MSH6/MLH1 panel (p = 0.125).

CONCLUSIONS

The two-protein panel, particularly MSH6/PMS2, offers high sensitivity and negative predictive value, suggesting its potential as a cost-effective alternative to the four-protein panel in MMR testing for endometrial cancer patients.

DNA mismatch repair system regulates the expression of PD-L1 through DNMTs in cervical cancer

BACKGROUND

Cervical cancer (CC) is a potential clinical application of PD-1/PD-L1 inhibitor. We aimed to study the mechanism of DNA mismatch repair (MMR) system regulating the expression of PD-L1 in CC through DNA methyltransferase (DNMTs).

METHODS

We collected pathological specimens from 118 cases of CC to analyze the relationship between PD-L1 expression and DNMTs in different MMR states. RNA interference (RNAi) technique was used to simulate the formation of CC cell line with MMR deficiency (dMMR) state, and subcutaneous tumor formation experiment was carried out in nude mice to verify the relationship between PD-L1 expression and DNMTs in MMR state.

RESULTS

The PD-L1 positive rate in 118 cases of CC was 58.47%, while the microsatellite instability (MSI) status accounted for 5.93%. There was a significant difference in the expression of PD-L1 between patients within the dMMR and MMR proficient (pMMR) groups (χ2 = 21.405, P < 0.001). Subcutaneous inoculation after infection of Siha cells led to successful tumorigenesis in nude mice, accompanied by a significant increase in the level of PD-L1 expression in the mouse tumors, while the expression level of MLH1 and MSH2 protein decreased significantly. We also found that PD-L1 expression was closely related to the expression of DNMTs.

CONCLUSION

PD-L1 is universal expressed on the surface of CC cells, dMMR status enhances the expression of PD-L1 on the surface of CC cells, dMMR states of CC are related to the demethylation status of the PD-L1 gene promoter region.

A tumor focused approach to resolving the etiology of DNA mismatch repair deficient tumors classified as suspected Lynch syndrome

Routine screening of tumors for DNA mismatch repair (MMR) deficiency (dMMR) in colorectal (CRC), endometrial (EC) and sebaceous skin (SST) tumors leads to a significant proportion of unresolved cases classified as suspected Lynch syndrome (SLS). SLS cases (n = 135) were recruited from Family Cancer Clinics across Australia and New Zealand. Targeted panel sequencing was performed on tumor (n = 137; 80×CRCs, 33×ECs and 24xSSTs) and matched blood-derived DNA to assess for microsatellite instability status, tumor mutation burden, COSMIC tumor mutational signatures and to identify germline and somatic MMR gene variants. MMR immunohistochemistry (IHC) and MLH1 promoter methylation were repeated. In total, 86.9% of the 137 SLS tumors could be resolved into established subtypes. For 22.6% of these resolved SLS cases, primary MLH1 epimutations (2.2%) as well as previously undetected germline MMR pathogenic variants (1.5%), tumor MLH1 methylation (13.1%) or false positive dMMR IHC (5.8%) results were identified. Double somatic MMR gene mutations were the major cause of dMMR identified across each tumor type (73.9% of resolved cases, 64.2% overall, 70% of CRC, 45.5% of ECs and 70.8% of SSTs). The unresolved SLS tumors (13.1%) comprised tumors with only a single somatic (7.3%) or no somatic (5.8%) MMR gene mutations. A tumor-focused testing approach reclassified 86.9% of SLS into Lynch syndrome, sporadic dMMR or MMR-proficient cases. These findings support the incorporation of tumor sequencing and alternate MLH1 methylation assays into clinical diagnostics to reduce the number of SLS patients and provide more appropriate surveillance and screening recommendations.

Characteristics of Mismatch Repair-Deficient Colon Cancer in Relation to Mismatch Repair Protein Loss, Hypermethylation Silencing, and Constitutional and Biallelic Somatic Mismatch Repair Gene Pathogenic Variants

BACKGROUND

Mismatch repair-deficient colon cancer is heterogeneous. Differentiating inherited constitutional variants from somatic genetic alterations and gene silencing is important for surveillance and genetic counseling.

OBJECTIVE

This study aimed to determine the extent to which the underlying mechanism of loss of mismatch repair influences molecular and clinicopathologic features of microsatellite instability-high colon cancer.

DESIGN

This is a retrospective analysis.

SETTINGS

This study was conducted at a comprehensive cancer center.

PATIENTS

Patients with microsatellite instability-high colon cancer of stage I, II, or III were included.

INTERVENTION

Patients underwent a curative surgical resection.

MAIN OUTCOME MEASURES

The main outcome measures were hypermethylation of the MLH1 promoter, biallelic inactivation, constitutional pathogenic variants, and loss of specific mismatch repair proteins.

RESULTS

Of the 157 identified tumors with complete genetic analysis, 66% had hypermethylation of the MLH1 promoter, 18% had constitutional pathogenic variants, (Lynch syndrome), 11% had biallelic somatic mismatch repair gene pathogenic variants, and 6% had unexplained high microsatellite instability. The distribution of mismatch repair loss was as follows: MLH1 and PMS2 co-loss, 79% of the tumors; MSH2 and MSH6 co-loss, 10%; MSH6 alone, 3%; PMS2 alone, 2%; other combinations, 2%; no loss, 2%. Tumor mutational burden was lowest in MLH1- and PMS2-deficient tumors. MSH6-deficient tumors had the lowest levels of tumor-infiltrating lymphocytes, lowest MSI scores, and fewest frameshift deletions. Patients with MLH1 promoter hypermethylation were significantly more likely to be older and female and to have right-sided colon lesions than patients with biallelic inactivation. Mutation was the most prevalent second hit in tumors with biallelic inactivation and tumors of patients with Lynch syndrome.

LIMITATIONS

This study was limited by potential selection or referral bias, missing data for some patients, and relatively small sizes of some subgroups.

CONCLUSIONS

Clinical characteristics of mismatch repair-deficient colon cancer vary with the etiology of microsatellite instability, and its molecular characteristics vary with the affected mismatch repair protein. See Video Abstract at http://links.lww.com/DCR/B984 .

CARACTERSTICAS DEL CNCER DE COLON CON DEFICIENCIA EN LA REPARACIN DE ERRORES DE EMPAREJAMIENTO EN RELACIN CON LA PRDIDA DE PROTENAS MMR, SILENCIAMIENTO DE LA HIPERMETILACIN Y LAS VARIANTES PATGENAS SOMTICAS DE GENES MMR CONSTITUCIONAL Y BIALLICO

ANTECEDENTES:El cáncer de colon deficiente en la reparación de errores de emparejamiento es heterogéneo. La diferenciación de las variantes constitucionales heredadas de las alteraciones genéticas somáticas y el silenciamiento de genes es importante para la vigilancia y el asesoramiento genético.OBJETIVO:Determinar hasta qué punto el mecanismo subyacente de pérdida de reparación de desajustes influye en las características moleculares y clinicopatológicas del cáncer de colon con alta inestabilidad de microsatélites.DISEÑO:Análisis retrospectivo.ESCENARIO:Centro integral de cáncer.PACIENTES:Pacientes con cáncer de colon con inestabilidad de microsatélites alta en estadio I, II, o III.INTERVENCIÓN:Resección quirúrgica con intención curativa.PRINCIPALES RESULTADOS Y MEDIDAS:Hipermetilación del promotor MLH1, inactivación bialélica, variante patógena constitucional y pérdida de proteínas específicas reparadoras de desajustes.RESULTADOS:De los 157 tumores identificados con un análisis genético completo, el 66 % tenía hipermetilación del promotor MLH1, el 18 % tenía una variante patogénica constitucional (síndrome de Lynch), el 11 % tenía variantes patogénicas somáticas bialélicas de algún gen MMR y el 6 % tenía una alta inestabilidad de microsatélites sin explicación. La distribución de la pérdida según la proteína de reparación del desajuste fue la siguiente: pérdida conjunta de MLH1 y PMS2, 79 % de los tumores; co-pérdida de MSH2 y MSH6, 10%; MSH6 solo, 3%; PMS2 solo, 2%; otras combinaciones, 2%; sin pérdida, 2%. La carga mutacional del tumor fue más baja en los tumores deficientes en MLH1 y PMS2. Los tumores con deficiencia de MSH6 tenían los niveles más bajos de linfocitos infiltrantes de tumores, las puntuaciones más bajas del sensor de IMS y la menor cantidad de deleciones por cambio de marco. Los pacientes con hipermetilación del promotor MLH1 tenían significativamente más probabilidades de ser mayores y mujeres y de tener lesiones en el colon derecho que los pacientes con inactivación bialélica. La mutación fue el segundo golpe más frecuente en tumores con inactivación bialélica y tumores de pacientes con síndrome de Lynch.LIMITACIONES:Sesgo potencial de selección o referencia, datos faltantes para algunos pacientes y tamaños relativamente pequeños de algunos subgrupos.CONCLUSIONES:Las características clínicas del cáncer de colon deficiente en reparación de desajustes varían con la etiología de la inestabilidad de microsatélites, y sus características moleculares varían con la proteína de reparación de desajustes afectada. Vea Resumen de video en http://links.lww.com/DCR/B984 . (Traducción-Dr. Felipe Bellolio ).

An exploration of gastric cancer with heterogeneous mismatch repair status

Survival benefits or symptom alleviation from immune checkpoint blockade therapy can be seen in microsatellite instability-high (MSI-H) cases. However, genetic heterogeneity within a specific subgroup of MSI-H tumors may be associated with poor response and prognosis. We investigated the molecular changes and microsatellite status of the cases with heterogeneous MMR protein staining by polymerase chain reaction (PCR) and next-generation sequencing (NGS). Data from 3723 patients with gastric cancer were retrospectively analyzed to determine the mismatch repair (MMR) status by performing immunohistochemical staining of four major MMR proteins (MLH1, PMS2, MSH2, and MSH6). When heterogeneous MMR protein staining result was positive, PCR and NGS were performed. Heterogeneous MMR protein staining was observed in 12 cases. In microsatellite stable (MSS) cases, TP53 mutation appeared to accompany heterogeneous staining (HS) of MLH1. However, TP53 variation was not observed with MSI-H occurrence. Cases showing heterogeneous MSH6 protein staining revealed MSH6 mutations. Some cases with the same MMR protein staining set had varying MSI results. In one case whose primary and metastatic foci presented MLH1-HS and PMS2-HS, the microsatellite status was classified as MSS and MSI-H, respectively. Moreover, HS was also found in multiple biopsies and surgical specimens. This study found a preliminary relationship between heterogeneously stained MSH6 or MLH1 proteins and their gene mutations, as well as between MSI-H/TP53 - and MSS/TP53 + tumors. The microsatellite status of patients with heterogeneous MMR protein staining is unpredictable. Given the heterogeneity of mismatch repair, microsatellite status should be assessed for all specimens if sufficient specimens can be obtained.

A tumor focused approach to resolving the etiology of DNA mismatch repair deficient tumors classified as suspected Lynch syndrome

Routine screening of tumors for DNA mismatch repair (MMR) deficiency (dMMR) in colorectal (CRC), endometrial (EC) and sebaceous skin (SST) tumors leads to a significant proportion of unresolved cases classified as suspected Lynch syndrome (SLS). SLS cases (n=135) were recruited from Family Cancer Clinics across Australia and New Zealand. Targeted panel sequencing was performed on tumor (n=137; 80xCRCs, 33xECs and 24xSSTs) and matched blood-derived DNA to assess for microsatellite instability status, tumor mutation burden, COSMIC tumor mutational signatures and to identify germline and somatic MMR gene variants. MMR immunohistochemistry (IHC) and MLH1 promoter methylation were repeated. In total, 86.9% of the 137 SLS tumors could be resolved into established subtypes. For 22.6% of these resolved SLS cases, primary MLH1 epimutations (2.2%) as well as previously undetected germline MMR pathogenic variants (1.5%), tumor MLH1 methylation (13.1%) or false positive dMMR IHC (5.8%) results were identified. Double somatic MMR gene mutations were the major cause of dMMR identified across each tumor type (73.9% of resolved cases, 64.2% overall, 70% of CRC, 45.5% of ECs and 70.8% of SSTs). The unresolved SLS tumors (13.1%) comprised tumors with only a single somatic (7.3%) or no somatic (5.8%) MMR gene mutations. A tumor-focused testing approach reclassified 86.9% of SLS into Lynch syndrome, sporadic dMMR or MMR-proficient cases. These findings support the incorporation of tumor sequencing and alternate MLH1 methylation assays into clinical diagnostics to reduce the number of SLS patients and provide more appropriate surveillance and screening recommendations.

Potential biomarkers in endometrial cancer: a narrative review

CONTEXT

Every year, approximately 0.4 million women suffer from endometrial cancer (EC) worldwide and it has become the most common gynecological malignancy. Almost 66% of EC cases are diagnosed at an early stage and can be cured by performing surgery while those at an advanced stage turns out to be fatal. Biomarkers of endometrial cancer would be very valuable for screening of women who are at high risk and in detecting the chance of recurrence of disease.

OBJECTIVE

The current article has reviewed studies published on expression of biomarkers and susceptibility to EC.

METHODS

Google Scholar and PubMed were used as searching platforms and we have majorly considered the literature from last 10 years.

RESULTS

Potential biomarkers of EC identified from various studies were summarised.

An unusual non‑metastatic, mismatch repair‑deficient primary gastric squamous cell carcinoma presenting as a large, exophytic, bleeding tumor: A case report

Primary gastric squamous cell carcinoma (GSCC) is an extremely rare malignancy with a poor prognosis. Despite the improved knowledge regarding its pathogenesis and biology, the treatment options remain limited. The present study reported on the unique case of a mismatch repair-deficient (dMMR) primary GSCC in a 79-year-old woman reporting fatigue and symptoms of upper gastrointestinal tract bleeding. Physical examination revealed abdominal pain at palpation. Gastroscopy revealed a large, exophytic, bleeding tumor. Medical imaging confirmed a mushroom-like polyp in the lumen of the stomach, with no signs of disease spread. Total gastrectomy and D2 lymphadenectomy were performed. Pathological examination of the post-operational material confirmed a well-differentiated SCC invading the mucosa, submucosa and muscle layer. There were no signs of dissemination observed in any of the 32 excised lymph nodes. Notably, according to the last follow-up, the patient remains well, supporting the 5-year GSCC survival rate statistics. To the best of our knowledge, this is the first such GSCC case reported in the Surgical Oncology Outpatient Clinic (Copernicus Memorial Hospital, Lodz, Poland) and these findings add to the limited data on GSCC. Although this is a very rare condition, it should always be considered during the process of diagnosis of gastric tumors.

Pulmonary Artery Intimal Sarcoma in a Patient with Lynch Syndrome: Response to an Immune Checkpoint Inhibitor

Intimal sarcoma is an extremely rare mesenchymal tumor arising in the great vessels. To date, intimal sarcoma has not been reported in patients with Lynch syndrome (LS), even though this syndrome lacks DNA mismatch repair ability genetically and is prone to various malignancies. This patient was diagnosed with LS by the Revised Amsterdam Criteria II, and she suffered from intimal sarcoma in the left pulmonary artery. She had a germline missense variant of PMS2 (c.1399G>A, pV467I) which is classified as a variant of unknown significance. In her intimal sarcoma, PMS2 expression was decreased. Additionally, it exhibited microsatellite instability and a high tumor mutational burden (69 mutations/Mb) which are features of mismatch repair deficiency, although PMS2 (c.1399G>A, pV467I) missense is a variant of unknown significance. The metastatic lesions of intimal sarcoma in this patient responded heterogeneously to pembrolizumab, an immune checkpoint inhibitor. Cytotoxic agents and radiation were also effective for some metastatic lesions, but some lesions, including her liver metastases, were resistant. The hypermutable nature of the LS genotype might acquire resistance to an immune checkpoint inhibitor and other cytotoxic agents such as occurred with her liver metastases.

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.

Microsatellite Instability Assessment by Immunohistochemistry in Acute Myeloid Leukemia: A Reappraisal and Review of the Literature

BACKGROUND

Microsatellite instability (MSI) is caused by defects in DNA mismatch repair (MMR) components. Inactivation of any MMR gene(s), including hMLH1, hMSH2, hMSH6, and hPMS2, can result in MSI. Immunohistochemistry (IHC) is a sensitive and specific screening tool for MSI that can detect loss of expression of one or more MMR components. Of the four MMR markers, hMLH1 and hMSH2 are considered most informative of MSI status. There has been renewed interest in MSI status in view of its favorable association with response to immune checkpoint inhibitors in some cancers. MMR expression patterns in acute myeloid leukemia (AML) have not been evaluated systematically.

METHODS

We used clinically-validated IHC assays to assess the expression of hMLH1, hMSH2, hMSH6, and/or hPMS2 in formalin-fixed paraffin-embedded tissue sections of bone marrow core biopsies from patients diagnosed with AML. Mutation profiling was performed using next-generation sequencing to assess for mutations in MMR genes.

RESULTS

The study group included 236 patients with AML, including a cohort treated on a clinical trial of azacitidine and nivolumab (NCT02397720). In addition, hMSH6, and/or hPMS2 expression was assessed in 99 AML patients with diploid karyotype. All patients, except two, had retained expression of all MMR markers assessed: One patient from the azacytidine+nivolumab group had zonal patchy loss of staining of hMLH1 and, to a lesser extent, a similar staining pattern of hMSH2; and one patient from the AML with diploid karyotype group had loss of hMSH2 but retained expression of hMLH1, hMSH6 and hPMS2. In addition, a retrospective analysis on a separate cohort of 139 patients with primary AML, on which next generation sequencing profiling was performed, identified 14 cases with alterations in MMR genes.

CONCLUSION AND REMARKS

MMR loss is a rare event in AML, thus does not appear to underlie response patterns to anti-PD1 therapy.

Risk assessment and genetic counseling for Lynch syndrome - Practice resource of the National Society of Genetic Counselors and the Collaborative Group of the Americas on Inherited Gastrointestinal Cancer

Identifying individuals who have Lynch syndrome involves a complex diagnostic workup that includes taking a detailed family history and a combination of various tests such as immunohistochemistry and/or molecular which may be germline and/or somatic. The National Society of Genetic Counselors and the Collaborative Group of the Americas on Inherited Gastrointestinal Cancer have come together to publish this practice resource for the evaluation of Lynch syndrome. The purpose of this practice resource was to provide guidance and a testing algorithm for Lynch syndrome as well as recommendations on when to offer testing. This practice resource does not replace a consultation with a genetics professional. This practice resource includes explanations in support of this and a summary of background data. While this practice resource is not intended to serve as a review of Lynch syndrome, it includes a discussion of background information and cites a number of key publications which should be reviewed for a more in-depth understanding. This practice resource is intended for genetic counselors, geneticists, gastroenterologists, surgeons, medical oncologists, obstetricians and gynecologists, nurses, and other healthcare providers who evaluate patients for Lynch syndrome.

Reporting Subclonal Immunohistochemical Staining of Mismatch Repair Proteins in Endometrial Carcinoma in the Times of Ever-Changing Guidelines

CONTEXT.—

The current College of American Pathologists reporting guideline for mismatch repair protein (MMRP) immunohistochemistry for Lynch syndrome (LS) screening considers the presence of any positive nuclear staining as intact MMRP expression. This would include tumors with combined areas of subclonal retention and loss of MMRP staining.

OBJECTIVE.—

To evaluate the clinical significance of reporting subclonal staining patterns of MMRP immunohistochemistry in endometrial carcinoma.

DESIGN.—

We retrospectively reviewed 455 consecutive MMRP immunohistochemistry results of endometrial carcinoma in hysterectomy specimens from 2012 through 2017 and identified cases with subclonal MMRP staining. These results were correlated with the patient's personal and family history of LS-associated carcinoma, MLH1 promoter methylation status, and LS genetic testing.

RESULTS.—

Subclonal staining of MMRP was seen in 48 of 455 cases (10.5%) on review. Thirty cases demonstrated isolated subclonal staining and were reported by pathologists as follows: subclonal (n = 5), complete MMRP loss (n = 4), and intact MMRP (n = 21). Eighteen cases had subclonal staining in combination with complete loss of other MMRP. Cases reported as subclonal or complete MMRP loss had appropriate clinical follow-up. Two of 2 cases with isolated subclonal MSH6 loss tested positive for LS. One of 3 cases with isolated subclonal MLH1/PMS2 loss was negative for MLH1 promoter methylation; LS genetic testing was not performed because of cost.

CONCLUSIONS.—

Our study reveals that LS germline mutation can be detected in endometrial carcinoma patients whose tumors display sole subclonal MMRP staining. Our results stress the importance of reporting subclonal staining patterns to ensure appropriate clinical follow-up.

MLH1/PMS2-deficient Endometrial Carcinomas in a Universally Screened Population: MLH1 Hypermethylation and Germline Mutation Status

MLH1/PMS2 loss due to epigenetic hypermethylation of the MLH1 promoter is the most common cause of mismatch repair deficiency in endometrial carcinoma, and typically provides reassurance against an associated germline mutation. To further characterize the genetic features of MLH1/PMS2-deficient endometrial cancers, the departmental database was searched for cases with dual MLH1/PMS2 loss and retained MSH2/6 expression which underwent MLH1 hypermethylation testing. Genetic testing results were obtained when available. One hundred seventeen endometrial cancers met inclusion criteria: 100 (85%) were MLH1-hypermethylated, 3 (3%) were low-level/borderline, 7 (6%) were nonmethylated, and 7 (6%) were insufficient for testing. Sixteen cases (12 MLH1-hypermethylated, 3 nonmethylated, and 1 insufficient for testing) underwent germline testing, 6 of which (37.5%) demonstrated germline variants of unknown significance (VUS) (MSH6, PMS2, POLD1, BRIP1, RAD51D, CHEK2) but no known deleterious mutations. Notably, however, the patients harboring the MSH6 and PMS2 germline VUS had clinical features concerning for Lynch syndrome. One nonmethylated, germline-normal case underwent somatic tumor testing, and demonstrated a somatic MLH1 mutation. In summary, MLH1-hypermethylation accounts for the vast majority of MLH1/PMS2-deficient cancers in a universally screened population, although MLH1 somatic and germline mutations can occur. Occasionally, patients with MLH1-hypermethlated tumors also bear germline VUS in other mismatch repair genes as well as genes implicated in other hereditary cancer syndromes, but their clinical relevance is unclear. Family and personal cancer histories must always be evaluated to determine the need for germline testing in women with loss of MLH1/PMS2, even in the setting of hypermethylation.

Mismatch Repair Deficiency and Somatic Mutations in Human Sinonasal Tumors

Simple Summary

Sinonasal carcinomas are rare tumors with an overall poor prognosis. Due to limitations in local therapeutic approaches, systemic neo-adjuvant or adjuvant therapies are becoming increasingly important in order to improve patient outcome. This study aimed to examine potentially therapeutic targetable molecular alterations in different sinonasal tumors, including deficiency in mismatch repair proteins and microsatellite instability as well as driver mutations. According to our results, immunohistochemical (IHC) analysis of mismatch repair (MMR) proteins and sequencing-based panel analysis should be integrated into the diagnostics of clinically aggressive inverted sinonasal papilloma (ISP) and sinonasal squamous cell carcinoma (SNSCC) in order to enable the therapeutic possibility of a targeted therapy.

Abstract

Due to limitations in local therapy approaches for sinonasal tumors, improvement in systemic therapies plays a pivotal role for prolongation of the patient’s survival. The aim of this study was to examine potential biomarkers, including deficiency in mismatch repair proteins (dMMR)/microsatellite instability (MSI-H) in sinonasal cancers and their precancerous lesions. A comprehensive analysis of 10 sinonasal cancer cell lines by whole exome sequencing, screening 174 sinonasal tumors by immunohistochemistry (IHC) for mismatch repair deficiency and next generation sequencing (NGS) of 136 tumor samples revealed a dMMR/MSI-H sinonasal squamous cell carcinoma (SNSCC) cell line based on a somatic missense mutation in MLH1 and an overall frequency of dMMR/MSI-H SNSCC of 3.2% (4/125). Targetable EGFR mutations were found in 89.3% (25/28) of inverted sinonasal papilloma (ISP) and in 60% (6/10) of ISP-associated carcinomas. While PIK3CA and EGFR mutations were not mutually exclusive, KRAS mutated tumors were an EGFR-wildtype. The effect of potential driver mutations in FGFR2, FGFR3, BRAF, HRAS, MAP2K1, PTEN, NOTCH1 and CARD11 need further investigation. Our results suggest that biomarker testing, including MMR-IHC and NGS panel analysis, should be integrated into the diagnostics of clinically aggressive ISPs and SNSCC to assess prognosis and facilitate therapeutic decisions.

The prevalence of DNA microsatellite instability in anaplastic thyroid carcinoma - systematic review and discussion of current therapeutic options

INTRODUCTION

Anaplastic thyroid carcinoma is a rare, rapidly progressing, highly aggressive thyroid malignancy. Responses to immune checkpoint inhibitors in mismatch repair-deficient/microsatellite instability-high tumours of other locations have shown promising results, and with the extended approval of the PD-1 receptor inhibitor pembrolizumab by the Food and Drug Administration, also anaplastic thyroid cancer (ATC) requires analysis for microsatellite instability (MSI) status.

MATERIAL AND METHODS

Systematic research for relevant literature was conducted in different databases. Prevalence, detection methods, and the potential prognostic/predictive value of MSI in view of the available targeted therapies were of special focus.

RESULTS

Selected citations revealed the prevalence of MSI in 7.4%, with mutations in the MSH2 gene (33%) being the most frequent, followed by MSH6 (25%) and MLH1 (16.7%) occurring in the following combinations: MLH1-MSH2 (8.3%), MSH2-MSH6 (8.3%), and MLH3-MSH5 (8.3%). No mutations in the PMS2 gene were reported. Sixty-six co-mutations in 9 cases were found, with TP53 (88.9%), NF1 (44.4 %), ATM (33.3%), and RB1 (33.3%) being the most frequent. No RAS mutations were noted. Survival ranged between 2.8 and 48 months, and patient age varied between 49 and 84 years. There are insufficient and heterogenous data concerning the predictive or prognostic value of mismatch repair-deficient/microsatellite instability status.

CONCLUSIONS

Tumour molecular profiling is fundamental in ATC for predictive, prognostic, as well as therapeutic reasons, and analysis of MSI status is strongly suggested because a small subgroup show the MSI signature and might profit from recently approved targeted therapies.

MLH1 promoter hypermethylation predicts poorer prognosis in mismatch repair deficiency endometrial carcinomas

Objective

The antitumor effects of anti-PD-1 antibody against mismatch repair deficiency (MMR-D)-associated cancers have been reported. MMR-D is found in approximately 20%–30% of endometrial carcinomas (ECs) and frequently occurs due to MLH1 promoter hypermethylation (MLH1-PHM). ECs with MLH1-PHM are classified according to the molecular screening of Lynch syndrome (LS), but few detailed reports are available. The purpose of this study was to clarify the clinical features of EC with MLH1-PHM.

Methods

Immunohistochemistry of MMR proteins (MLH1, MSH2, MSH6, and PMS2) was performed on specimens from 527 ECs treated at our university hospital from 2003 to 2018. MLH1 methylation analysis was added to cases with MLH1/PMS2 loss. ECs were classified as follows: cases that retained MMR proteins as “MMR-proficient;” cases with MLH1/PMS2 loss and MLH1-PHM as “met-EC;” and cases with other MMR protein loss and MLH1/PMS2 loss without MLH1-PHM as “suspected-LS.” The clinical features, including long-term prognosis, of each group, were analyzed.

Results

Accordingly, 419 (79.5%), 65 (12.3%), and 43 (8.2%) cases were categorized as “MMR-proficient,” “suspected-LS,” and “met-EC,” respectively. Significantly, “met-EC” had a lower proportion of grade 1 tumors (37.5%) and a higher proportion of stage III/IV tumors (37.2%) than the other groups. The overall and progression-free survival of “met-EC” were significantly worse than those of “suspected-LS” in all cases.

Conclusion

In ECs with MMR-D, “met-ECs” were a subgroup with a poorer prognosis than “suspected-LS.” “Met-ECs” would be the main target for anti-PD-1 antibody treatment, and its clinical susceptibility should be verified individually.

Comprehensive analysis of DNA mismatch repair-deficient gastric cancer in a Japanese hospital-based population

BACKGROUND

The attention on mismatch repair-deficient (dMMR) gastric cancer has increased in this era of anti-PD-1 blockade therapy; however, the prevalence and molecular genetics of patients with dMMR gastric cancer have not been completely investigated.

METHODS

Immunohistochemistry of MMR proteins (MLH1, MSH2, MSH6 and PMS2) was performed on formalin-fixed paraffin-embedded sections prepared from resected primary gastric cancers of 513 consecutive patients. Genetic and/or epigenetic alterations of the MMR genes were also investigated.

RESULTS

Loss of expression of one or more MMR proteins was observed in 58 patients (11.3%); 54 patients showed loss of MLH1/PMS2, 3 patients showed loss of MLH1/PMS2/MSH6 and 1 patient showed loss of PMS2 alone. Among these 58 patients, 55 showed hypermethylation of the promoter region of MLH1. Genetic testing revealed that the remaining three patients had Lynch syndrome (n = 1) or Lynch-like syndrome (n = 2). A total of 15 patients (25.9% of all patients with dMMR gastric cancer and 2.9% of all patients with gastric cancer), including 11 patients with stage I-III dMMR gastric cancer who had recurrence and 4 patients with stage IV dMMR gastric cancer, are potential candidates for the use of anti-PD-1 blockades.

CONCLUSIONS

This is the first study to investigate the frequency and molecular genetic mechanisms of dMMR gastric cancer comprehensively, focusing on the benefit of using PD-1 blockades. Our observations will be beneficial in the clinical practice of metastatic gastric cancer.

Testing strategies for Lynch syndrome in people with endometrial cancer: systematic reviews and economic evaluation

BACKGROUND

Lynch syndrome is an inherited genetic condition that is associated with an increased risk of certain cancers. The National Institute for Health and Care Excellence has recommended that people with colorectal cancer are tested for Lynch syndrome. Routine testing for Lynch syndrome among people with endometrial cancer is not currently conducted.

OBJECTIVES

To systematically review the evidence on the test accuracy of immunohistochemistry- and microsatellite instability-based strategies to detect Lynch syndrome among people who have endometrial cancer, and the clinical effectiveness and the cost-effectiveness of testing for Lynch syndrome among people who have been diagnosed with endometrial cancer.

DATA SOURCES

Searches were conducted in the following databases, from inception to August 2019 - MEDLINE ALL, EMBASE (both via Ovid), Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials (both via Wiley Online Library), Database of Abstracts of Reviews of Effects, Health Technology Assessment Database (both via the Centre for Reviews and Dissemination), Science Citation Index, Conference Proceedings Citation Index - Science (both via Web of Science), PROSPERO international prospective register of systematic reviews (via the Centre for Reviews and Dissemination), NHS Economic Evaluation Database, Cost-Effectiveness Analysis Registry, EconPapers (Research Papers in Economics) and School of Health and Related Research Health Utilities Database. The references of included studies and relevant systematic reviews were also checked and experts on the team were consulted.

REVIEW METHODS

Eligible studies included people with endometrial cancer who were tested for Lynch syndrome using immunohistochemistry- and/or microsatellite instability-based testing [with or without mutL homologue 1 (MLH1) promoter hypermethylation testing], with Lynch syndrome diagnosis being established though germline testing of normal (non-tumour) tissue for constitutional mutations in mismatch repair. The risk of bias in studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool, the Consolidated Health Economic Reporting Standards and the Philips' checklist. Two reviewers independently conducted each stage of the review. A meta-analysis of test accuracy was not possible because of the number and heterogeneity of studies. A narrative summary of test accuracy results was provided, reporting test accuracy estimates and presenting forest plots. The economic model constituted a decision tree followed by Markov models for the impact of colorectal and endometrial surveillance, and aspirin prophylaxis with a lifetime time horizon.

RESULTS

The clinical effectiveness search identified 3308 studies; 38 studies of test accuracy were included. (No studies of clinical effectiveness of endometrial cancer surveillance met the inclusion criteria.) Four test accuracy studies compared microsatellite instability with immunohistochemistry. No clear difference in accuracy between immunohistochemistry and microsatellite instability was observed. There was some evidence that specificity of immunohistochemistry could be improved with the addition of methylation testing. There was high concordance between immunohistochemistry and microsatellite instability. The economic model indicated that all testing strategies, compared with no testing, were cost-effective at a willingness-to-pay threshold of £20,000 per quality-adjusted life-year. Immunohistochemistry with MLH1 promoter hypermethylation testing was the most cost-effective strategy, with an incremental cost-effectiveness ratio of £9420 per quality-adjusted life-year. The second most cost-effective strategy was immunohistochemistry testing alone, but incremental analysis produced an incremental cost-effectiveness ratio exceeding £130,000. Results were robust across all scenario analyses. Incremental cost-effectiveness ratios ranged from £5690 to £20,740; only removing the benefits of colorectal cancer surveillance produced an incremental cost-effectiveness ratio in excess of the £20,000 willingness-to-pay threshold. A sensitivity analysis identified the main cost drivers of the incremental cost-effectiveness ratio as percentage of relatives accepting counselling and prevalence of Lynch syndrome in the population. A probabilistic sensitivity analysis showed, at a willingness-to-pay threshold of £20,000 per quality-adjusted life-year, a 0.93 probability that immunohistochemistry with MLH1 promoter hypermethylation testing is cost-effective, compared with no testing.

LIMITATIONS

The systematic review excluded grey literature, studies written in non-English languages and studies for which the reference standard could not be established. Studies were included when Lynch syndrome was diagnosed by genetic confirmation of constitutional variants in the four mismatch repair genes (i.e. MLH1, mutS homologue 2, mutS homologue 6 and postmeiotic segregation increased 2). Variants of uncertain significance were reported as per the studies. There were limitations in the economic model around uncertainty in the model parameters and a lack of modelling of the potential harms of gynaecological surveillance and specific pathway modelling of genetic testing for somatic mismatch repair mutations.

CONCLUSION

The economic model suggests that testing women with endometrial cancer for Lynch syndrome is cost-effective, but that results should be treated with caution because of uncertain model inputs.

FUTURE WORK

Randomised controlled trials could provide evidence on the effect of earlier intervention on outcomes and the balance of benefits and harms of gynaecological cancer surveillance. Follow-up of negative cases through disease registers could be used to determine false negative cases.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42019147185.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Evidence Synthesis programme and will be published in full in Health Technology Assessment; Vol. 25, No. 42. See the NIHR Journals Library website for further project information.

Diagnosis of Lynch Syndrome and Strategies to Distinguish Lynch-Related Tumors from Sporadic MSI/dMMR Tumors

Simple Summary

Microsatellite instability (MSI) is a hallmark of Lynch syndrome (LS)-related tumors but is not specific, as most of MSI/mismatch repair-deficient (dMMR) tumors are sporadic. Therefore, the identification of MSI/dMMR requires additional diagnostic tools to identify LS. In this review, we address the hallmarks of LS and present recent advances in diagnostic and screening strategies to identify LS patients. We also discuss the pitfalls associated with current strategies, which should be taken into account in order to improve the diagnosis of LS.

Abstract

Microsatellite instability (MSI) is a hallmark of Lynch syndrome (LS)-related tumors but is not specific to it, as approximately 80% of MSI/mismatch repair-deficient (dMMR) tumors are sporadic. Methods leading to the diagnosis of LS have considerably evolved in recent years and so have tumoral tests for LS screening and for the discrimination of LS-related to MSI-sporadic tumors. In this review, we address the hallmarks of LS, including the clinical, histopathological, and molecular features. We present recent advances in diagnostic and screening strategies to identify LS patients. We also discuss the pitfalls associated with the current strategies, which should be taken into account to improve the diagnosis of LS and avoid inappropriate clinical management.

Prevalence and molecular characteristics of DNA mismatch repair deficient endometrial cancer in a Japanese hospital-based population

BACKGROUND

The prevalence and molecular characteristics of defective DNA mismatch repair endometrial cancers in the Japanese population have been underexplored. Data supporting clinical management of patients with Lynch-like syndrome and germline variant of uncertain significance of mismatch repair genes are still lacking.

METHODS

Immunohistochemistry of mismatch repair proteins (MLH1, MSH2, MSH6 and PMS2) was performed on formalin-fixed paraffin-embedded sections prepared from resected primary endometrial cancers in 395 women with a median age of 59 years. Genetic and/or epigenetic alterations of the mismatch repair genes were also investigated.

RESULTS

Loss of expression of one or more mismatch repair proteins was observed in 68 patients (17.2%). A total of 17 out of 68 patients (25%, 4.3% of all cases) were identified as candidates for genetic testing for Lynch syndrome after excluding 51 patients with MLH1 hypermethylated cancer. Fourteen of these 17 patients subjected to genetic testing were found to have Lynch syndrome (n = 5), germline variant of uncertain significance (n = 2) or Lynch-like syndrome (n = 7). Compared with patients with Lynch syndrome, those with germline variant of uncertain significance and Lynch-like syndrome tended to demonstrate an older age at the time of endometrial cancer diagnosis (P = 0.07), less fulfillment of the revised Bethesda guidelines (P = 0.09) and lower prevalence of Lynch syndrome-associated tumors in their first-degree relatives (P = 0.01).

CONCLUSIONS

This study provides useful information for management in patients with DNA mismatch repair endometrial cancer. Specifically, cancer surveillance as recommended in patients with Lynch syndrome might not be necessary in patients with germline variant of uncertain significance and Lynch-like syndrome and their relatives.

Clinicopathological features of mismatch repair protein expression patterns in colorectal cancer

Microsatellite instability (MSI) is reflective of a deficient mismatch repair (dMMR) system, which is mostly associated with the methylation of mismatch repair (MMR) genes and BRAF mutations in sporadic colorectal cancers (CRCs). We performed a retrospective study to analyze the clinicopathological features of dMMR CRCs and their association with the BRAF V600E mutation. The incidence of dMMR CRCs in our cohort was 7.4 % (118/1603). Immunohistochemistry (IHC) revealed four common dMMR IHC patterns in 116 dMMR CRCs from 110 patients. dMMR type 1 (MLH1-/PMS2-) CRCs were the most frequent pattern, usually showing typical proximal location and MSI histology. The BRAF V600E mutation was almost exclusively observed in dMMR type 1 (32 of 72) and dMMR type 2 (PMS- only, 7 of 18) CRCs (p = 0.001). Patients with dMMR type 3 (MSH2-/MSH6-) CRCs were usually diagnosed at younger ages (p < 0.001) and had the strongest family history of Lynch syndrome-associated tumors (p = 0.002). dMMR type 3 CRCs frequently presented at advanced stages (p = 0.005) with perineural invasion (p = 0.021). We also found a significant positive association of dMMR type 1 and type 3 with advanced stages of CRC, whereas dMMR types 2 and 4 (MSH6- only) were usually diagnosed at early stages of CRC (p < 0.001). In conclusion, BRAF V600E mutations almost exclusively occurred in dMMR type 1 and 2 CRCs. Patterns of MMR protein expression display distinct associations with tumor staging and age at diagnosis.

Universal Mismatch Repair Protein Screening in Upper Tract Urothelial Carcinoma

OBJECTIVES

Universal screening of upper tract urothelial carcinoma (UTUC) for Lynch syndrome by mismatch repair (MMR) protein immunohistochemistry (IHC) has been recommended by some investigators. Herein, we assess this recommendation retrospectively by simulating its performance on a retrospective, unselected cohort of UTUCs, with comparison to the established setting of colorectal and endometrial adenocarcinoma.

METHODS

We assessed for complete loss of MMR protein (MLH1, MSH2, MSH6, and PMS2) IHC in 74 consecutive cases of UTUC and then tabulated clinical and pathologic factors. MMR findings from same-institution colorectal and endometrial adenocarcinomas were tabulated for comparison.

RESULTS

We observed loss of at least one MMR protein in 12% in our UTUC cohort (three MSH2/MSH6, three MSH6 only, one MLH1/PMS2, and two PMS2 only). Of these nine cases (seven males, two females, median age 67 years, five associated with colorectal adenocarcinoma), at least three (4% of the overall cohort) proved to be Lynch syndrome. Overall, MMR loss in UTUC was comparable to colorectal (11%; 50 of 471 cases) and endometrial (12%; 12 of 101 cases) adenocarcinomas.

CONCLUSIONS

The rate of MMR loss observed in UTUC was comparable to that in the established setting of colorectal and endometrial adenocarcinomas, supporting universal UTUC screening at our institution and others.

Next generation sequencing to decipher concurrent loss of PMS2 and MSH6 in colorectal cancer

Background

Immunohistochemistry (IHQ) is commonly used for the detection of mismatch repair proteins deficiency (MMRD). One very infrequent abnormal pattern of MMR protein expression is the loss of PMS2 and MSH6, with intact expression of MLH1 and MSH2.

Case presentation

We review the frequency of this MMRD IHC pattern among 108 colorectal (CRCs) and 35 endometrial cancers in our files with loss of expression of at least one protein, and present two CRCs showing loss of PMS2 and MSH6 protein expression (1.9% of CRCs). NGS analysis of these tumours identified PMS2 mutations (R134* germline mutation in one tumour and M1R and c.1239delA somatic mutation in the other) as the primary event and somatic MSH6 mutation (c.3261dupC) as the secondary event in both tumours.

Conclusions

This study suggests that Next Generation Sequencing (NGS) tumour analysis should be considered in the algorithm of Lynch syndrome screening to detect MMR gen somatic mutation in inconclusive cases.

MMR deficiency in urothelial carcinoma of the bladder presents with temporal and spatial homogeneity throughout the tumor mass

BACKGROUND

Microsatellite instability (MSI), a hypermutator phenotype described in many cancers, has emerged as a predictive biomarker for immune checkpoint inhibitor therapy. Cancer heterogeneity represents a potential obstacle for the analysis of predicitive biomarkers. MSI has been reported in bladder cancer, but data on the possible extent of intratumoral heterogeneity are lacking.

METHODS

To study MSI heterogeneity in bladder cancer, a tissue microarray (TMA) comprising 598 muscle-invasive urothelial carcinomas of the bladder was utilized to screen for MSI by immunhistochemistry with antibodies for MLH1, PMS2, MSH2, and MSH6.

RESULTS

In 9 cases suspicious for MSI, MMR status was further evaluated by large section examination and polymerase chain reaction (PCR)-based analysis of microsatellites ("Bethesda panel") resulting in the identification of 5 validated MSI cases from 448 interpretable cancers (prevalence 1.1%). MMR deficiency always involved PMS2 loss, in 3 cases with additional loss or reduction of MLH1 expression. Four cancers were MSI-high and 1 was MSI-low in the PCR analysis. Parallel sequencing revealed an inactivating MLH1 mutation in 1 tumor but no further known pathogenic MMR gene mutations were found. Immunostaining of all available 72 cancer-containing tissue blocks of the 5 confirmed bladder cancer with MSI including prior and subsequent biopsies showed complete homogeneity of the MMR protein defects and the status of the 4 MMR proteins did not markedly change in sequential resections. In all 4 cases with noninvasive precursor lesions, MSI was also detectable.

CONCLUSION

These data suggest that MSI occurs early in invasive bladder cancer and immunohistochemical MMR analysis on limited biopsy material is sufficient to estimate MMR status of the entire cancer mass.

Comparison of screening strategies for Lynch syndrome in patients with newly diagnosed endometrial cancer: a prospective cohort study in China

Background

The prevalence of Lynch syndrome and screening strategies for this disorder in Chinese patients with endometrial cancer have seldom been investigated. Such data would be essential for the screening, prevention, genetic counseling, and treatment of Lynch syndrome. The purpose of this prospective study was to determine the accuracy of the mismatch repair (MMR) protein immunohistochemistry (IHC), microsatellite instability (MSI) test, and clinical diagnostic criteria in screening for Lynch syndrome-associated endometrial cancer (LS-EC) in a prospective Chinese cohort.

Methods

All patients with newly diagnosed endometrial cancer (EC) were evaluated using clinical diagnostic criteria (Amsterdam II criteria and the revised Bethesda guidelines), MSI test, and IHC of MMR proteins in tumor tissues. For all patients, the screening results were compared with results of germline sequencing for pathogenic variants of MMR genes.

Results

Between December 2017 and August 2018, a total of 111 unselected patients with newly diagnosed EC were enrolled. Six patients (5.4%) harbored a pathogenic germline mutation of MMR genes: 1 had a mutation in MutL homolog 1 (MLH1), 2 in MutS homolog 2 (MSH2), and 3 in MutS homolog 6 (MSH6). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for identifying LS-EC were 33.3%, 88.6%, 14.3%, and 95.9%, for the clinical criteria, 66.7%, 75.0%, 14.3%, and 97.3% for IHC of MMR proteins, 100%, 89.9%, 33.3%, and 100% for MSI test, and 100%, 72.4%, 20.0% and 100% for combined IHC and MSI test, respectively. The combination of IHC and MSI test had higher sensitivity and PPV than the clinical criteria (p = 0.030). MSI test and IHC were highly concordant for LS-EC screening (73/77, 94.8%).

Conclusion

The accuracy of the combination of IHC of MMR proteins and MSI test for screening LS among Chinese patients with EC was superior to that of the clinical criteria.

Trial registration NCT03291106. Registered on September 25, 2017

Immunohistochemical Expression of MMR Proteins with Clinicopathological Correlation in Colorectal Cancer in Egypt

BACKGROUND

Microsatellite instability (MSI) is the genetic pathway underlying 15% of sporadic colorectal carcinoma (CRC) and hereditary non-polyposis CRC. MSI-H CRC has a distinct clinicopathological characteristic including excess mucin and signet ring component, proximal colon, Crohn's like reaction, lymphocytic infiltration, and better survival.

AIM

This research aims to screen Egyptian CRC patients for MSI status by IHC testing of expression of the MMR proteins in correlation to its clinicopathological features.

MATERIAL AND METHODS

Immunohistochemistry study for mismatch repair proteins (MMR) was done on 115 cases of CRC. Their expressions were assessed and correlated to clinicopathological parameters in an attempt to obtain the most significant predictors of MSI.

RESULTS

MSI (low and high) represents 67% of the study cases. The most frequent expression pattern was combined loss of MLH, and PMS2 (38% of MSI) followed by a combined loss of MSH2, and MSH6 (29% of MSI). There was significant correlation of expression pattern of MMR proteins with the laterality, lymphovascular emboli, perineural invasion, grade, T stage, N stage, signet ring component, tumor infiltrating lymphocyte, and peritumoral lesion (0.014, 0.035, 0.012, 0.033, 0.013, 0.000, 0.041, 0.012, and 0.009 respectively). Proximal location (right sided) and lower grade, higher nodal stage, and marked TIL were selected as predictors of MS-H CRC (0.005, 0.031, 0.025, and 0.000 respectively).

CONCLUSION

All clinicopathological and histological parameters should be assessed in CRC for the sake of predicting MSI. The optimal approach to MSI evaluation is (IHC) assessment of MMR proteins.

The proportion of endometrial cancers associated with Lynch syndrome: a systematic review of the literature and meta-analysis

Purpose

Endometrial cancer (EC) is often the sentinel cancer in women with Lynch syndrome (LS). However, efforts to implement universal LS screening in EC patients have been hampered by a lack of evidence detailing the proportion of EC patients that would be expected to screen positive for LS.

Methods

Studies were identified by electronic searches of Medline, Embase, Cochrane CENTRAL and Web of Science. Proportions of test positivity were calculated by random and fixed-effects meta-analysis models. I² score was used to assess heterogeneity across studies.

Results

Fifty-three studies, including 12,633 EC patients, met the inclusion criteria. The overall proportion of endometrial tumors with microsatellite instability or mismatch repair (MMR) deficiency by immunohistochemistry (IHC) was 0.27 (95% confidence interval [CI] 0.25–0.28, I²: 71%) and 0.26 (95% CI 0.25–0.27, I²: 88%), respectively. Of those women with abnormal tumor testing, 0.29 (95% CI 0.25–0.33, I²: 83%) had LS-associated pathogenic variants on germline testing; therefore around 3% of ECs can be attributed to LS. Preselection of EC cases did increase the proportion of germline LS diagnoses.

Conclusion

The current study suggests that prevalence of LS in EC patients is approximately 3%, similar to that of colorectal cancer patients; therefore our data support the implementation of universal EC screening for LS.

Lynch Syndrome: From Screening to Diagnosis to Treatment in the Era of Modern Molecular Oncology

Lynch syndrome is a hereditary cancer predisposition syndrome caused by germline alterations in the mismatch repair genes and is the most common etiology of hereditary colorectal cancer. While Lynch syndrome was initially defined by the clinical Amsterdam criteria, these criteria lack the sensitivity needed for clinical utility. This review covers the evolution of screening for Lynch syndrome from the use of tumor microsatellite instability and/or somatic alterations in mismatch repair protein expression by immunohistochemistry to the newest methods using next-generation sequencing. Additionally, it discusses the clinical implications of the diagnosis of Lynch syndrome as it affects cancer therapeutics and the role of screening in noncolorectal Lynch-associated cancers. As molecular oncology continues to evolve, it is crucial to remain current on the increasing complexity of Lynch syndrome diagnostics and treatment options.

Clinicopathologic and Molecular Characteristics of Synchronous Colorectal Carcinoma With Mismatch Repair Deficiency

Synchronous colorectal carcinoma (CRC) is a unique disease associated with a high prevalence (∼35%) of microsatellite instability and occasionally with Lynch syndrome. The clinicopathologic and molecular features of synchronous CRC are poorly understood, particularly in Japanese patients. We examined 118 Japanese patients (236 tumors) with synchronous CRC and 117 Japanese patients (117 tumors) with solitary CRC with immunohistochemical staining for TP53 and mismatch repair (MMR) protein (MLH1, MSH2, PMS2, and MSH6) and mutation analyses of KRAS and BRAF genes. The results revealed no significant differences in clinicopathologic, histologic, and molecular findings between the synchronous and solitary CRC groups. Among the 118 synchronous CRC patients, 15 (12.7%) showed loss of MMR protein(s) expression in at least 1 tumor, whereas 103 (87.3%) showed intact expression of all 4 MMR proteins in both tumors. Of note, all patients with MMR deficiency had excellent prognoses. The 15 patients were further subdivided into 2 groups: the Concordant group, with concordant MMR loss (n=9, 7.6%) and the Discordant group, with discordant MMR loss (n=6, 5.1%). The Concordant patients showed concurrent MLH1/PMS2 loss (n=3), concurrent MSH2/MSH6 loss (n=4) and isolated MSH6 loss (n=2) in both tumors, whereas the Discordant patients showed concurrent MLH1/PMS2 loss (n=2), isolated PMS2 loss (n=2) and isolated MSH6 loss (n=2) in a single tumor. On the basis of the MMR expression pattern and BRAF mutation, the Concordant and Discordant groups were suspected to include Lynch syndrome, Lynch-like syndrome and sporadic MLH1 promoter hypermethylated CRC. In addition, KRAS mutation was present in only 1 tumor in a single patient in each group. In conclusion, the frequency of MMR protein deficiency in synchronous CRC in the Japanese population may be lower compared with the reported data from Western populations. MMR protein loss and KRAS and BRAF mutations in synchronous CRCs were heterogenous even in an individual patient.

A potpourri of pathogenetic pathways in endometrial carcinoma with a focus on Lynch Syndrome

Endometrial carcinoma is the most frequently occurring female genital tract malignancy in developed nations, with a rising annual incidence. Endometrioid endometrial carcinoma (EEC), the most common histological variant, differs in morphologic and molecular characteristics from serous carcinomas but morphological distinction of high-grade EECs from serous carcinomas may prove difficult. Thus, molecular categorization of tumors may allow for better tumor classification with greater insight into the underlying biology of endometrial carcinomas with new therapeutic options. Microsatellite instability (MSI) is a commonly occurring molecular aberration in EECs and has been identified in most Lynch Syndrome (LS) associated tumors. This tumor syndrome predisposes afflicted individuals to a myriad of tumors including endometrial carcinoma. Herein, the molecular signature of endometrial tumors as well as LS, and its clinical manifestations are reviewed. Understanding of the pathogenetic pathways allows for greater comprehension of occurrences at a molecular level which are then appreciated at a cellular and tissue level, by the histopathologist. The molecular classification of endometrial tumors allows for further targeted therapeutic options for affected patients. Screening tests for patients with suspected LS enables surveillance of other tumors in the affected patient and her family with the potential to decrease morbidity and mortality. It is envisioned that this overview will allow for enhanced comprehension of genetic pathways by practicing pathologists, oncologists, gynecologists and other members of the multidisciplinary team, all of whom are involved in the management of the patient with an endometrial malignancy.

Heterogenous loss of mismatch repair (MMR) protein expression: a challenge for immunohistochemical interpretation and microsatellite instability (MSI) evaluation

Immunohistochemistry (IHC) for mismatch repair (MMR) proteins is used to identify MMR status: being diffusely positive (intact/retained nuclear staining) or showing loss of nuclear tumour staining (MMR protein deficient). Four colonic adenocarcinomas and a gastric adenocarcinoma with associated dysplasia that displayed heterogenous IHC staining patterns in at least one of the four MMR proteins were characterised by next‐generation sequencing (NGS). In order to examine a potential molecular mechanism for these staining patterns, the respective areas were macrodissected, analysed for microsatellite instability (MSI) and investigated by NGS and multiplex ligation‐dependent probe amplification (MLPA) analysis of MLH1, MSH2, MSH6 and PMS2 genes, including MLH1 methylation analysis. One colonic adenocarcinoma showed heterogenous MSH6 IHC staining and molecular analysis demonstrated increasing allelic burden of two MSH6 frameshift variants (c.3261delC and c.3261dupC) in areas with MSH6 protein loss compared to areas where MSH6 was retained. Two colonic adenocarcinomas with heterogenous MLH1 staining showed no differences in sequence variants. In one of these cases, however, MLH1 was hypermethylated in the area of MLH1 loss. Another colon carcinoma with heterogenous PMS2 staining (but with retained MSH6) showed both MSH6 c.3261dupC and 3260_3261dupCC where PMS2 protein was lost and only c.3261dupC where PMS2 was retained. The gastric carcinoma showed complete loss of MSH6 in dysplastic foci, while the underlying invasive carcinoma showed retention of MSH6. Both these areas, however, were MSI‐high and showed the same MSH6 variant: c.3261delC. The gastric dysplasia additionally showed MSH6 c.3261dupC. In four of the five cases where MMR protein was lost, these areas were MSI‐high. Heterogenous MMR IHC (focal and/or zonal within the same tumour or between invasive and dysplastic preinvasive areas) is not always due to artefact and is invariably related to MSI‐high status in the areas of loss. An interesting aspect to this study is the presence of MSH6 somatic mutations irrespective of whether MSH6 IHC staining was intact or lost.

Peritumoral granulomatous reaction in endometrial carcinoma: association with DNA mismatch repair protein deficiency, particularly loss of PMS2 expression

AIMS

The observation of peritumoral granulomatous reactions (PGRs) in two endometrial carcinomas (ECs) with a PMS2-deficient/MLH1-intact expression pattern led us to investigate whether PGRs in EC were specifically associated with DNA mismatch repair (MMR) protein deficiency, particularly PMS2 loss.

METHODS AND RESULTS

Hysterectomy specimens from 22 MMR protein-intact and 54 MMR protein-deficient ECs were reviewed with specific attention to the presence of a PGR and a tumour-associated lymphoid reaction [including tumour-infiltrating lymphocytes (TILs) and stromal lymphoid infiltrates]. The MMR protein-deficient ECs included 22 cases with combined MLH1/PMS2 loss, 11 with combined MSH2/MSH6 loss, 11 with isolated MSH6 loss, and 10 with PMS2 loss but intact MLH1 staining (including the two 'index' cases). Overall, PGRs were identified in seven of 54 (13%) MMR protein-deficient ECs, five of which showed a PMS2-deficient/MLH1-intact immunophenotype; three of these patients had germline PMS2 mutations and one additional patient had a germline MSH6 mutation. None of the MMR protein-intact tumours showed a PGR. Although five of the seven PGR-positive ECs had a high-grade histological component, six were stage I. Most ECs with PGRs also showed TILs and stromal lymphoid reactions, similarly to MMR protein-deficient ECs in general.

CONCLUSIONS

MMR protein-deficient ECs, particularly those with PMS2 loss, occasionally show PGRs in addition to stromal lymphoid infiltrates and TILs. Therefore, PGRs could be considered to constitute a histological prompt for consideration of Lynch syndrome. The potential prognostic significance of PGRs in EC requires further study.

Limited impact of intratumour heterogeneity on molecular risk assignment in endometrial cancer

Introduction

Individual prediction of tumour behaviour based on molecular markers may refine adjuvant treatment strategies in endometrial cancer (EC). As these molecular alterations are determined in a small tumour fraction, high intratumour heterogeneity may interfere with correct risk prediction. This study aimed to investigate to which extent intratumour heterogeneity exists for molecular markers and whether it affects the molecular risk assignment in EC.

Methods

Forty-nine ECs (three tumour blocks/case) were selected with alterations in POLE (n=10), CTNNB1 (n=8), p53 (n=10), mismatch repair (n=11), L1CAM (n=10), and ECs without any of these markers (n=9). Nine ECs carried more than one molecular marker. All 147 blocks were analysed for POLE exonuclease domain and CTNNB1 exon 3 mutations, and for p53, mismatch repair and L1CAM protein expression. All blocks were assigned to a favourable, intermediate or unfavourable risk group, based on a molecular risk assignment.

RESULTS

Concordance between the three tumour blocks for POLE and CTNNB1 mutational status, and p53, mismatch repair and L1CAM protein expression was found in 100% (48/48), 95.9% (47/49), 93.9% (46/49), 98.0% (48/49), and 91.8% (45/49) of tumours, respectively. These discordances were found in a total of nine cases (18.4%). The intratumour heterogeneity impacted the risk assignment in five cases (10.2%).

Conclusion

Intratumour heterogeneity of prognostic molecular markers in EC without morphologic heterogeneity is uncommon among three tumour fractions, affecting the molecular risk allocation in a limited number of cases. This low intratumour heterogeneity facilitates the implementation of the molecular risk assignment, advocating its use in clinical decision making.

Immunohistochemical Pitfalls: Common Mistakes in the Evaluation of Lynch Syndrome

At least 15% of colorectal cancers diagnosed in the United States are deficient in mismatch repair mechanisms. Most of these are sporadic, but approximately 3% of colorectal cancers result from germline alterations in mismatch repair genes and represent Lynch syndrome. It is critical to identify patients with Lynch syndrome to institute appropriate screening and surveillance for patients and their families. Exclusion of Lynch syndrome in sporadic cases is equally important because it reduces anxiety for patients and prevents excessive spending on unnecessary surveillance. Immunohistochemistry is one of the most widely used screening tools for identifying patients with Lynch syndrome.

Clinical characteristics of Lynch-like cases collaterally classified by Lynch syndrome identification strategy using universal screening in endometrial cancer

OBJECTIVE

Lynch syndrome (LS), an autosomal-dominant inherited disorder, increases the risk for LS-associated cancers (LS-AC). Molecular LS assessment for all cases is referred to as universal screening (U/S) and is recommended for endometrial cancer (EC) and colorectal cancer. Lynch-like cases (LL) lack LS-pathogenic mutations despite being suspected as LS by U/S, but have been poorly investigated in EC. The aim of this study was to capture the features of LL in EC and to devise LL management in EC.

METHODS

U/S, consisting of immunohistochemistry and reflex methylation analysis, was applied to 348 Asian ECs, and sporadic cancer (SC) cases were screened out. Genetic testing was offered to "suspected-LS" cases selected by U/S. The features of the LS, LL, and SC groups were recorded and compared.

RESULTS

U/S screened 306 ECs as SC. The recurrence rates of suspected-LS and SC cases were 14.3% (6/42) and 26.5% (81/306), respectively. Of the 42 suspected-LS cases, 10 were identified as LS, 17 were classified as LL, and 15 did not undergo genetic testing. In the LS group, the frequency of personal history (50%) and family history (100%) of LS-AC were prominent. Of note, the prevalence of family history of LS-AC and gastric cancer was significantly higher in the LL group than in the SC group (76.5% vs. 38.6% and 47.1% vs. 25.2%, respectively).

CONCLUSIONS

Herein, we report the features of LL classified by LS identification via U/S in Asian EC. LL should be candidates for tailored surveillance based on regionality and family history.

AGO Austria recommendation on screening and diagnosis of Lynch syndrome (LS)

Purpose

This manuscript reports the consensus recommendations on screening and diagnosis of Lynch syndrome (LS) in patients with endometrial or ovarian cancer as well as on possible preventive measures in effectively LS-diagnosed women. The recommendations are issued by the Austrian Arbeitsgemeinschaft für Gynäkologische Onkologie (AGO) of the Österreichischen Gesellschaft für Gynäkologie und Geburtshilfe (OEGGG) after consultation of the most recent and relevant literature and following deliberation by the Genetic Task-Force convoked May, 2015 by the AGO Council.

Results and conclusion

The Austrian AGO recommends immunohistochemical tissue screening for type-I and type-II endometrial cancers in all patients below the age of 70 years, and for all endometrioid and clear-cell ovarian cancers independently of the patient’s age. If needed immunohistochemistry should be complemented by tissue MLH1 promotor hypermethylation testing and/or microsatellite instability (MSI) analysis. The diagnosis LS requires confirmation through identification of a germline mutation by a molecular genetic examination in the mismatch repair genes using the patient’s blood. This should be performed without preceding tissue screening when in LS-associated cancer patients the family history fulfills the Amsterdam II or the revised Bethesda criteria. In LS-diagnosed women, the age for prophylactic surgery should be set flexibly based on an informed consent. Regarding the monitoring of these women, chemo-preventive measures as well as screening procedures either to avoid or to early detect LS-related tumors are discussed with a special light on their specific limitations.

BRIP1 coding variants are associated with a high risk of hepatocellular carcinoma occurrence in patients with HCV- or HBV-related liver disease

The molecular mechanisms of hepatocellular carcinoma (HCC) carcinogenesis are still not fully understood. DNA repair defects may influence HCC risk. The aim of the study was to look for potential genetic variants of DNA repair genes associated with HCC risk among patients with alcohol- or viral-induced liver disease. We performed four case-control studies on 2,006 European- (Derivation#1 and #2 studies) and African-ancestry (Validation#1 and #2 studies) patients originating from several cohorts in order to assess the association between genetic variants on DNA repair genes and HCC risk using a custom array encompassing 94 genes. In the Derivation#1 study, the BRIP1 locus reached array-wide significance (Chi-squared SV-Perm, P=5.00×10^-4) among the 253 haplotype blocks tested for their association with HCC risk, in patients with viral cirrhosis but not among those with alcoholic cirrhosis. The BRIP1 haplotype block included three exonic variants (rs4986763, rs4986764, rs4986765). The BRIP1 'AAA' haplotype was significantly associated with an increased HCC risk [odds ratio (OR), 2.01 (1.19-3.39); false discovery rate (FDR)-P=1.31×10^-2]. In the Derivation#2 study, results were confirmed for the BRIP1 'GGG' haplotype [OR, 0.53 (0.36-0.79); FDR-P=3.90×10^-3]. In both Validation#1 and #2 studies, BRIP1 'AAA' haplotype was significantly associated with an increased risk of HCC [OR, 1.71 (1.09-2.68); FDR-P=7.30×10^-2; and OR, 6.45 (4.17-9.99); FDR-P=2.33×10^-19, respectively]. Association between the BRIP1 locus and HCC risk suggests that impaired DNA mismatch repair might play a role in liver carcinogenesis, among patients with HCV- or HBV-related liver disease.