Prognostic significance of POLE proofreading mutations in endometrial cancer

Molecular-based classification algorithm for endometrial carcinoma categorizes ovarian endometrioid carcinoma into prognostically significant groups

The Cancer Genome Atlas classification divides endometrial carcinoma in biologically distinct groups, and testing for p53, mismatch repair proteins (MMR), and polymerase ɛ (POLE) exonuclease domain mutations has been shown to predict the molecular subgroup and clinical outcome. While abnormalities in these markers have been described in ovarian endometrioid carcinoma, their role in predicting its molecular profile and prognosis is still not fully explored. Patients with ovarian endometrioid carcinomas treated surgically in a 14-year period were selected. Only tumors with confirmation of endometrioid histology and negative WT1 and Napsin-A were included. POLE mutational analysis and immunohistochemistry for p53, MLH1, MSH2, MSH6, and PMS2 was performed in formalin-fixed, paraffin-embedded tissue. Following the molecular classifier proposed for endometrial carcinoma (Br J Cancer2015;113:299-310), cases were classified as POLE mutated, MMR abnormal, p53 abnormal, and p53 wild type. Clinicopathologic information was recorded, including patient outcome. In all, 72 cases were included, distributed as follows: 7 (10%) POLE mutated; 6 (8%) MMR abnormal; 17 (24%) p53 abnormal; and 42 (58%) p53 wild type. The molecular classification correlated with disease-free survival in multivariate analysis (P=0.003), independently of tumor grade and stage. Correlation with overall survival approached statistical significance (P=0.051). POLE-mutated and MMR-abnormal tumors had excellent survival, whereas p53-abnormal tumors had significantly higher rates of recurrence and death. Ovarian endometroid carcinoma can be classified in clinically meaningful subgroups by testing for molecular surrogates, akin to endometrial cancer. MMR and POLE alterations seem to identify a subset of ovarian endometrioid carcinomas with excellent outcome; conversely, abnormal p53 carries a worse prognosis. In the era of personalized medicine, the use of these markers in the routine evaluation of ovarian endometrioid tumors should be considered.

Prognostic Significance of POLE Exonuclease Domain Mutations in High-Grade Endometrioid Endometrial Cancer on Survival and Recurrence: A Subanalysis

OBJECTIVE

POLE mutations in high-grade endometrioid endometrial cancer (EEC) have been associated with improved survival. We sought to investigate the prevalence of POLE tumor mutation and its prognostic significance on outcomes and clinical applications in a subanalysis of women with high-grade EEC from a previously described cohort of 544 EEC patients in which POLE mutation status and survival outcomes were assessed.

METHODS

Polymerase chain reaction amplification and Sanger sequencing were used to test for POLE mutations in 72 tumors. Associations between POLE mutation, demographic and clinicopathologic features, and survival were investigated with Cox proportional hazard models.

RESULTS

POLE mutations were identified in 7 (9.7%) of 72 grade 3 EECs. No significant differences in the clinicopathologic features between those with POLE mutations and those without were identified. Adjusted for age, a decreased risk of recurrence was suggested in patients with a POLE mutation (adjusted hazard ratio, 0.37; 95% confidence interval, 0.09-1.55), as well as decreased risk of death (adjusted hazard ratio, 0.19; 95% confidence interval, 0.03-1.42).

CONCLUSIONS

POLE mutations in tumors of women with grade 3 EEC are associated with a lower risk of recurrence and death, although not statistically significant because of high variability in these estimates. These findings, consistent with recently published combined analyses, support POLE mutation status as a noteworthy prognostic marker and may favor a change in the treatment of women with grade 3 EECs, particularly in those with early-stage disease, in which omission of adjuvant therapy and decreased surveillance could possibly be appropriate.

Assessing Tumor-Infiltrating Lymphocytes in Solid Tumors: A Practical Review for Pathologists and Proposal for a Standardized Method from the International Immuno-Oncology Biomarkers Working Group: Part 2: TILs in Melanoma, Gastrointestinal Tract Carcinomas, Non-Small Cell Lung Carcinoma and Mesothelioma, Endometrial and Ovarian Carcinomas, Squamous Cell Carcinoma of the Head and Neck, Genitourinary Carcinomas, and Primary Brain Tumors

Assessment of the immune response to tumors is growing in importance as the prognostic implications of this response are increasingly recognized, and as immunotherapies are evaluated and implemented in different tumor types. However, many different approaches can be used to assess and describe the immune response, which limits efforts at implementation as a routine clinical biomarker. In part 1 of this review, we have proposed a standardized methodology to assess tumor-infiltrating lymphocytes (TILs) in solid tumors, based on the International Immuno-Oncology Biomarkers Working Group guidelines for invasive breast carcinoma. In part 2 of this review, we discuss the available evidence for the prognostic and predictive value of TILs in common solid tumors, including carcinomas of the lung, gastrointestinal tract, genitourinary system, gynecologic system, and head and neck, as well as primary brain tumors, mesothelioma and melanoma. The particularities and different emphases in TIL assessment in different tumor types are discussed. The standardized methodology we propose can be adapted to different tumor types and may be used as a standard against which other approaches can be compared. Standardization of TIL assessment will help clinicians, researchers and pathologists to conclusively evaluate the utility of this simple biomarker in the current era of immunotherapy.

Potential role of radiation therapy in augmenting the activity of immunotherapy for gynecologic cancers

Immune checkpoint inhibitors have become an area of intense interest in oncology and are actively being studied in a variety of cancer types with a wide range of success. In vitro data suggest mechanisms by which radiation can activate the immune system, and ongoing studies are exploring the potential interaction of checkpoint inhibitors with radiotherapy in both preclinical and clinical settings. Gynecologic malignancies are a heterogeneous group of tumors with varying prognoses, intrinsic immunogenicity, and potential for response to immune-based therapies. In this review, we focus on the rationale for immunotherapy and opportunities for augmentation by photon radiotherapy in cancers of the cervix, endometrium, and ovary.

Checkpoint inhibitors in endometrial cancer: preclinical rationale and clinical activity

CONTEXT

Treatment of advanced and recurrent endometrial cancer (EC) is still an unmet need for oncologists and gynecologic oncologists. The Cancer Genome Atlas Research Network (TCGA) recently provided a new genomic classification, dividing EC in four subgroups. Two types of EC, the polymerase epsilon (POLE)-ultra-mutated and the microsatellite instability-hyper-mutated (MSI-H), are characterized by a high mutation rate providing the rationale for a potential activity of checkpoint inhibitors.

MATERIALS AND METHODS

We analyzed all available evidence supporting the role of tumor microenvironment (TME) in EC development and the therapeutic implications offered by immune checkpoint inhibitors in this setting. We performed a review on Pubmed with Mesh keywords 'endometrial cancer' and the name of each checkpoint inhibitor discussed in the article. The same search was operated on clinicaltrial.gov to identify ongoing clinical trials exploring PD-1/PD-L1 and CTLA-4 axis in EC, particularly focusing on POLE-ultra-muted and MSI-H cancer types.

RESULTS

POLE-ultra-mutated and MSI-H ECs showed an active TME expressing high number of neo-antigens and an elevated amount of tumor infiltrating lymphocytes (TILs). Preliminary results from a phase-1 clinical trial (KEYNOTE-028) demonstrated antitumor activity of Pembrolizumab in EC. Moreover, both Pembrolizumab and Nivolumab reported durable clinical responses in POLE-ultra-mutated patients.

CONCLUSIONS

Immune checkpoint inhibitors are an attractive option in POLE-ultra-mutated and MSI-H ECs. Future investigations in these subgroups include combinations of checkpoints inhibitors with chemotherapy and small tyrosine kinase inhibitors (TKIs) to enhance a more robust intra-tumoral immune response.

POLE somatic mutations in advanced colorectal cancer

Despite all the knowledge already gathered, the picture of somatic genetic changes in colorectal tumorigenesis is far from complete. Recently, germline and somatic mutations in the exonuclease domain of polymerase epsilon, catalytic subunit (POLE) gene have been reported in a small subset of microsatellite‐stable and hypermutated colorectal carcinomas (CRCs), affecting the proofreading activity of the enzyme and leading to misincorporation of bases during DNA replication. To evaluate the role of POLE mutations in colorectal carcinogenesis, namely in advanced CRC, we searched for somatic mutations by Sanger sequencing in tumor DNA samples from 307 cases. Microsatellite instability and mutation analyses of a panel of oncogenes were performed in the tumors harboring POLE mutations. Three heterozygous mutations were found in two tumors, the c.857C>G, p.Pro286Arg, the c.901G>A, p.Asp301Asn, and the c.1376C>T, p.Ser459Phe. Of the POLE‐mutated CRCs, one tumor was microsatellite‐stable and the other had low microsatellite instability, whereas KRAS and PIK3CA mutations were found in one tumor each. We conclude that POLE somatic mutations exist but are rare in advanced CRC, with further larger studies being necessary to evaluate its biological and clinical implications.

Mixed endometrial carcinomas with a "low-grade serous"-like component: a clinicopathologic, immunohistochemical, and molecular genetic study

Recently, we reported 2 mixed endometrioid endometrial carcinomas with a "low-grade serous"-like component, which does not fit into any of the 4 molecular groups described by The Cancer Genome Atlas. To understand the nature of these tumors, we have done an immunohistochemical and molecular genetic study of these 2 cases and added a third case. Immunoreactivity for p53, ER, Ki67, WT1, MLH1, PMS2, MSH2, and MSH6 was assessed. Targeted next-generation sequencing for somatic mutations, including genes commonly implicated in carcinogenesis including TP53, KRAS, and PIK3CA, and Sanger sequencing for PTEN and POLE were also performed. All patients were nulliparous and had morbid obesity. Their tumors showed a micropapillary component that resembled that of ovarian low-grade serous carcinoma and merged with villoglandular endometrioid carcinoma. The invasive tumor glands exhibited a microcystic, elongated, or fragmented pattern and contained psammoma bodies. Two tumors showed aberrant p53 expression, and all 3 were positive for ER. All showed KRAS mutations, and TP53 mutations were found in 2 cases. One patient developed peritoneal carcinomatosis, one patient is alive with disease, and another died of a brain tumor. The third patient, whose tumor was confined to the uterus (stage IA), is alive without evidence of disease, but she has been followed for only 6 months. Mixed endometrial carcinomas with a "low-grade" serous-like component exhibit a morphologic spectrum of endometrioid and serous differentiation with microcystic, elongated, or fragmented features; ER expression; KRAS and TP53 mutations; and aggressive behavior.

Blinded histopathological characterisation of POLE exonuclease domain-mutant endometrial cancers: sheep in wolf's clothing

AIMS

POLE exonuclease domain mutations identify a subset of endometrial cancer (EC) patients with an excellent prognosis. The use of this biomarker has been suggested to refine adjuvant treatment decisions, but the necessary sequencing is not widely performed and is relatively expensive. Therefore, we aimed to identify histopathological and immunohistochemical characteristics to aid in the detection of POLE-mutant ECs.

METHODS AND RESULTS

Fifty-one POLE-mutant endometrioid, 67 POLE-wild-type endometrioid and 15 POLE-wild-type serous ECs were included (total N = 133). An expert gynaecopathologist, blinded to molecular features, evaluated each case (two or more slides) for 16 morphological characteristics. Immunohistochemistry was performed for p53, p16, MLH1, MSH2, MSH6, and PMS2. POLE-mutant ECs were characterised by a prominent immune infiltrate: 80% showed peritumoral lymphocytes and 59% showed tumour-infiltrating lymphocytes, as compared with 43% and 28% of POLE-wild-type endometrioid ECs, and 27% and 13% of their serous counterparts (P < 0.01, all comparisons). Of POLE-mutant ECs, 33% contained tumour giant cells; this proportion was significantly higher than that in POLE-wild-type endometrioid ECs (10%; P = 0.003), but not significantly different from that in serous ECs (53%). Serous-like features were as often (focally) present in POLE-mutant as in POLE-wild-type endometrioid ECs (6-24%, depending on the feature). The majority of POLE-mutant ECs showed wild-type p53 (86%), negative/focal p16 (82%) and normal mismatch repair protein expression (90%).

CONCLUSIONS

A simple combination of morphological and immunohistochemical characteristics (tumour type, grade, peritumoral lymphocytes, MLH1, and p53 expression) can assist in prescreening for POLE exonuclease domain mutations in EC, increasing the probability of a mutation being detected from 7% to 33%. This facilitates the use of this important prognostic biomarker in routine pathology.

TP53 Mutational Spectrum in Endometrioid and Serous Endometrial Cancers

Endometrial carcinomas (ECs) are heterogeneous at the genetic level. Although TP53 mutations are highly recurrent in serous endometrial carcinomas (SECs), these are also present in a subset of endometrioid endometrial carcinomas (EECs). Here, we sought to define the frequency, pattern, distribution, and type of TP53 somatic mutations in ECs by performing a reanalysis of the publicly available data from The Cancer Genome Atlas (TCGA). A total of 228 EECs (n=186) and SECs (n=42) from the TCGA data set, for which an integrated genomic characterization was performed, were interrogated for the presence and type of TP53 mutations, and for mutations in genes frequently mutated in ECs. TP53 mutations were found in 15% of EECs and 88% of SECs, and in 91% of copy-number-high and 35% of polymerase (DNA directed), epsilon, catalytic subunit (POLE) integrative genomic subtypes. In addition to differences in prevalence, variations in the type and pattern of TP53 mutations were observed between histologic types and between integrative genomic subtypes. TP53 hotspot mutations were significantly more frequently found in SECs (46%) than in EECs (15%). TP53-mutant EECs significantly more frequently harbored a co-occurring PTEN mutation than TP53-mutant SECs. Finally, a subset of TP53-mutant ECs (22%) was found to harbor frameshift or nonsense mutations. Given that nonsense and frameshift TP53 mutations result in distinct p53 immunohistochemical results that require careful interpretation, and that EECs and SECs display different patterns, types, and distributions of TP53 mutations, the use of the TP53/p53 status alone for the differential diagnosis of EECs and SECs may not be sufficient.

The genetic landscape of endometrial clear cell carcinomas

Clear cell carcinoma of the endometrium is a rare type of endometrial cancer that is generally associated with an aggressive clinical behaviour. Here, we sought to define the repertoire of somatic genetic alterations in endometrial clear cell carcinomas (ECCs), and whether ECCs could be classified into the molecular subtypes described for endometrial endometrioid and serous carcinomas. We performed a rigorous histopathological review, immunohistochemical analysis and massively parallel sequencing targeting 300 cancer-related genes of 32 pure ECCs. Eleven (34%), seven (22%) and six (19%) ECCs showed abnormal expression patterns for p53, ARID1A, and at least one DNA mismatch repair (MMR) protein, respectively. Targeted sequencing data were obtained from 30 of the 32 ECCs included in this study, and these revealed that two ECCs (7%) were ultramutated and harboured mutations affecting the exonuclease domain of POLE. In POLE wild-type ECCs, TP53 (46%), PIK3CA (36%), PPP2R1A (36%), FBXW7 (25%), ARID1A (21%), PIK3R1 (18%) and SPOP (18%) were the genes most commonly affected by mutations; 18% and 11% harboured CCNE1 and ERBB2 amplifications, respectively, and 11% showed DAXX homozygous deletions. ECCs less frequently harboured mutations affecting CTNNB1 and PTEN but more frequently harboured PPP2R1A and TP53 mutations than non-POLE endometrioid carcinomas from The Cancer Genome Atlas (TCGA). Compared to endometrial serous carcinomas (TCGA), ECCs less frequently harboured TP53 mutations. When a surrogate model for the molecular-based TCGA classification was used, all molecular subtypes previously identified in endometrial endometrioid and serous carcinomas were present in the ECCs studied, including POLE, MMR-deficient, copy-number high (serous-like)/p53 abnormal, and copy-number low (endometrioid)/p53 wild-type, which were significantly associated with disease-free survival in univariate analysis. These findings demonstrate that ECCs constitute a histologically and genetically heterogeneous group of tumours with varying outcomes. Furthermore, our data suggest that the classification of ECCs as being generally 'high-grade' or 'type II' tumours may not be warranted. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Hypermutated tumours in the era of immunotherapy: The paradigm of personalised medicine

Immune checkpoint inhibitors have demonstrated unprecedented clinical activity in a wide range of cancers. Significant therapeutic responses have recently been observed in patients presenting mismatch repair-deficient (MMRD) tumours. MMRD cancers exhibit a remarkably high rate of mutations, which can result in the formation of neoantigens, hypothesised to enhance the antitumour immune response. In addition to MMRD tumours, cancers mutated in the exonuclease domain of the catalytic subunit of the DNA polymerase epsilon (POLE) also exhibit an ultramutated genome and are thus likely to benefit from immunotherapy. In this review, we provide an overview of recent data on hypermutated tumours, including MMRD and POLE-mutated cancers, with a focus on their distinctive clinicopathological and molecular characteristics as well as their immune environment. We also discuss the emergence of immune therapy to treat these hypermutated cancers, and we comment on the recent Food and Drug Administration approval of an immune checkpoint inhibitor, the programmed cell death 1 antibody (pembrolizumab, Keytruda), for the treatment of patients with metastatic MMRD cancers regardless of the tumour type. This breakthrough represents a turning point in the management of these hypermutated tumours and paves the way for broader strategies in immunoprecision medicine.

Novel SOX17 frameshift mutations in endometrial cancer are functionally distinct from recurrent missense mutations

Extensive genomic profiling for endometrioid endometrial carcinoma (EEC) has pointed to genes and pathways important in uterine development as critical mediators of endometrial tumorigenesis. SOX17 is a developmental transcription factor necessary for proper endoderm formation that has been implicated as a tumor suppressor and shown to modulate WNT signaling. SOX17 mutation analysis in 539 primary EECs revealed frequent missense and frameshift mutations with an overall 11.5% mutation rate. More than half the mutations identified were frameshifts (32 of 62), and the hotspot missense changes, p.Ala96Gly and p.Ser403Ile, were seen in 14 tumors. None of the cases with a mutation had a second SOX17 mutation or evidence of allelic loss. Immunofluorescence microscopy performed on primary samples showed that there were no changes in SOX17 protein expression associated with mutation. Low/absent SOX17 staining was significantly associated with advanced stage, high tumor grade and reduced recurrence-free survival. Functional assessment of the two hotspot missense mutations and three representative frameshift mutations showed that SOX17-A96G and SOX17-S403I have transcriptional activities similar to SOX17 wild-type (WT), whereas none of the frameshift mutant proteins showed transcriptional activity. Forced expression of SOX17-WT, -A96G or -S403I in EC cell lines moderately increased β-catenin mediated transcription, which contrasts with previous data showing SOX17 is an inhibitor of TCF/β-catenin signaling. The proliferation of EC cell lines was expectedly reduced by transfection with SOX17-WT, and further reduced by SOX17-A96G and SOX17-S403I. These data implicate SOX17 mutation as a selected event in EEC, with clear differences between the missense and frameshift mutations.

Molecular Pathology: Predictive, Prognostic, and Diagnostic Markers in Uterine Tumors

This article focuses on the diagnostic, prognostic, and predictive molecular biomarkers in uterine malignancies, in the context of morphologic diagnoses. The histologic classification of endometrial carcinomas is reviewed first, followed by the description and molecular classification of endometrial epithelial malignancies in the context of histologic classification. Taken together, the molecular and histologic classifications help clinicians to approach troublesome areas encountered in clinical practice and evaluate the utility of molecular alterations in the diagnosis and subclassification of endometrial carcinomas. Putative prognostic markers are reviewed. The use of molecular alterations and surrogate immunohistochemistry as prognostic and predictive markers is also discussed.

Endometrial cancer gene panels: clinical diagnostic vs research germline DNA testing

Endometrial cancer is the most common gynecological cancer, but is nevertheless uncommon enough to have value as a signature cancer for some hereditary cancer syndromes. Commercial multigene testing panels include up to 13 different genes annotated for germline DNA testing of patients with endometrial cancer. Many other genes have been reported as relevant to familial endometrial cancer from directed genome-wide sequencing studies or multigene panel testing, or research. This review assesses the evidence supporting association with endometrial cancer risk for 32 genes implicated in hereditary endometrial cancer, and presents a summary of rare germline variants in these 32 genes detected by analysis of quasi-population-based endometrial cancer patients from The Cancer Genome Atlas project. This comprehensive investigation has led to the conclusion that convincing evidence currently exists to support clinical testing of only six of these genes for diagnosis of hereditary endometrial cancer. Testing of endometrial cancer patients for the remaining genes should be considered in the context of research studies, as a means to better establish the level of endometrial cancer risk, if any, associated with genetic variants that are deleterious to gene or protein function. It is acknowledged that clinical testing of endometrial cancer patients for several genes included on commercial panels may provide actionable findings in relation to risk of other cancers, but these should be considered secondary or incidental findings and not conclusive evidence for diagnosis of inherited endometrial cancer. In summary, this review and analysis provides a comprehensive report of current evidence to guide the selection of genes for clinical and research gene testing of germline DNA from endometrial cancer patients.

Mixed and Ambiguous Endometrial Carcinomas: A Heterogenous Group of Tumors With Different Clinicopathologic and Molecular Genetic Features

Besides endometrioid, serous, and clear cell carcinomas, there are endometrial carcinomas exhibiting mixed and ambiguous morphologic features. We have analyzed the immunophenotype (p53, p16, β-catenin, ER, HNF-1B, MLH1, and Ki-67) and mutational status (PTEN, KRAS, PIK3CA, and POLE) of 7 mixed carcinomas and 13 ambiguous carcinomas, all of them classified initially as mixed carcinomas. Only 2 of the 7 (28%) mixed carcinomas showed different immunophenotypes in different components. All but 2 tumors (5/7, 71%) overexpressed p53 and p16 and were negative for ER. Both carcinomas (2/7, 28%) showed a prominent micropapillary component that resembled an ovarian low-grade serous carcinoma and merged with villoglandular endometrioid carcinoma. The ambiguous carcinomas exhibited glandular architecture, high nuclear grade, and overlapping features of endometrioid and serous carcinomas. All tumors overexpressed p53 and p16, and the majority of cases (12/13, 92%) were negative for ER. KRAS mutations were identified in 3 of 7 (42%) mixed carcinomas, including the 2 cases with a "low-grade" serous-like component. PIK3CA mutations occurred in 2 (2/13, 15%) ambiguous carcinomas and PTEN mutations in 1 (1/7, 14%) mixed and 1 (1/13, 8%) ambiguous carcinoma. POLE exonuclease domain mutations were encountered in a case of mixed undifferentiated and well-differentiated (dedifferentiated) carcinoma. Two of the 7 (29%) mixed endometrial carcinomas and 5 of the 13 (38%) ambiguous carcinomas had extended beyond the pelvis (stages III and IV). Two of the 7 (29%) patients with mixed endometrial carcinoma and 6 of 12 (50%) patients with ambiguous endometrial carcinoma were alive with disease or had died of tumor. Our results show that, biologically, many so-called mixed carcinomas represent serous carcinomas with ambiguous morphology. Our series include 2 true mixed endometrial carcinomas with a "low-grade serous"-like component, microcystic, elongated, or fragmented features, KRAS mutations, and aggressive behavior.

DNA Damage and Repair Biomarkers of Immunotherapy Response

DNA-damaging agents are widely used in clinical oncology and exploit deficiencies in tumor DNA repair. Given the expanding role of immune checkpoint blockade as a therapeutic strategy, the interaction of tumor DNA damage with the immune system has recently come into focus, and it is now clear that the tumor DNA repair landscape has an important role in driving response to immune checkpoint blockade. Here, we summarize the mechanisms by which DNA damage and genomic instability have been found to shape the antitumor immune response and describe clinical efforts to use DNA repair biomarkers to guide use of immune-directed therapies.Significance: Only a subset of patients respond to immune checkpoint blockade, and reliable predictive biomarkers of response are needed to guide therapy decisions. DNA repair deficiency is common among tumors, and emerging experimental and clinical evidence suggests that features of genomic instability are associated with response to immune-directed therapies. Cancer Discov; 7(7); 675-93. ©2017 AACR.

[Current prerequisites for a molecular genetic classification of endometrial cancer]

The review analyzes current investigators' data on the introduction of an additional endometrial cancer classification based on the results of molecular and genetic studies. This necessity is dictated by clinical observations, according to which the genetic profile of the tumors may not correspond to their morphological structure, which considerably changes patient management tactics. The existing dualistic model of carcinogenesis makes it possible to identify and describe the characteristic molecular features of the tumors in terms of their histological structure. The review also analyzes the concept of 4 new endometrial cancer subgroups: ultramutated, hypermutated, copy-number low, and copy-number high (serous-like). It gives the results of investigations of the molecular and genetic characteristics of each subgroup. Particular attention is paid to the role of POLE gene mutations in the ultramutated subgroup. Different theories justifying a good prognosis in these patients are considered. The molecular characteristics of endometrial cancer versus tumors of other organs are compared. The potential benefits of introducing the new classification, which allow one to change approaches to stratifying the risk for this disease, are presented.

Replicative DNA polymerase defects in human cancers: Consequences, mechanisms, and implications for therapy

The fidelity of DNA replication relies on three error avoidance mechanisms acting in series: nucleotide selectivity of replicative DNA polymerases, exonucleolytic proofreading, and post-replicative DNA mismatch repair (MMR). MMR defects are well known to be associated with increased cancer incidence. Due to advances in DNA sequencing technologies, the past several years have witnessed a long-predicted discovery of replicative DNA polymerase defects in sporadic and hereditary human cancers. The polymerase mutations preferentially affect conserved amino acid residues in the exonuclease domain and occur in tumors with an extremely high mutation load. Thus, a concept has formed that defective proofreading of replication errors triggers the development of these tumors. Recent studies of the most common DNA polymerase variants, however, suggested that their pathogenicity may be determined by functional alterations other than loss of proofreading. In this review, we summarize our current understanding of the consequences of DNA polymerase mutations in cancers and the mechanisms of their mutator effects. We also discuss likely explanations for a high recurrence of some but not other polymerase variants and new ideas for therapeutic interventions emerging from the mechanistic studies.

The Genomic Heterogeneity of FIGO Grade 3 Endometrioid Carcinoma Impacts Diagnostic Accuracy and Reproducibility

The Cancer Genome Atlas (TCGA) identified 4 groups of endometrial carcinomas based on an integrated genomic characterization: POLE ultramutated (POLE), microsatellite instability-high, copy number-low (CN-L), and copy number-high (CN-H). In that study, CN-H comprised all of the serous carcinoma cases and 25% of all International Federation of Gynecology and Obstetrics (FIGO) Grade 3 endometrioid carcinoma cases. In this study, 2 expert gynecologic pathologists undertook a morphologic reassessment of the FIGO Grade 3 endometrioid carcinoma subset of the TCGA study cohort, including an analysis for evidence of serous differentiation. Interobserver variability κvalues are reported for the histologic evaluation of all 4 genomic clusters, and diagnostic discrepancies are discussed. Overall, there were 55 agreements, 6 disagreements, and 14 deferrals. Of the 75 cases analyzed, 6 cases had a consensus morphologic diagnosis of serous carcinoma, but only 2 of these cases had a serous carcinoma genotype, whereas the remaining 4 cases were genotypically endometrioid carcinoma. For the CN-H group, 2 of 15 cases were serous carcinoma by morphology and genotype, whereas at least 1 pathologist interpreted the remaining 13 cases as endometrioid carcinoma. The interobserver agreement rate was highest in the CN-L group (90%; κ=0.9), compared with the other genomic groups (POLE: 62%, κ=0.55; microsatellite instability-high: 78%, κ=0.74; and CN-H: 53%, κ=0.48). Our review confirms that most high-grade endometrial carcinomas diagnosed by TCGA as FIGO Grade 3 endometrioid carcinoma are indeed endometrioid carcinomas by morphology and genotype, and that the reproducibility of histologic diagnosis between pathologists varies between the TCGA-integrated genomic clusters.

The changing landscape of gynaecological cancer diagnosis: implications for histopathological practice in the 21st century

The era of molecular medicine has led to dramatically improved understanding of the genetic events that give rise to different types of cancers. In the case of gynaecological malignancies, this has resulted in distinct shifts in how these tumours are diagnosed in routine surgical pathology practice, with an increased emphasis on accurate subtype diagnosis. This has happened across all sites in the gynaecological tract and for most cell types, but in ways that are site-specific and may appear to be subtle, as in most instances the diagnostic terminology has not changed. For example, the diagnosis of clear cell carcinoma of the ovary is still in use, but the diagnostic criteria and clinical implications are different in 2017 from what they were in 2000. As a result, there can be a failure to appreciate how important these changes are and the resulting necessity of incorporating them into our daily practice. In this review we will describe changes in diagnostic surgical pathology occasioned by improved understanding of molecular events during pathogenesis, for cancers of ovary/tube, endometrium, cervix and vulva, and highlight how current practice differs from that of only a few years ago.

Chromatin remodelling and DNA repair genes are frequently mutated in endometrioid endometrial carcinoma

In developed countries, endometrial carcinoma is the most common cancer that affects the female genital tract. Endometrial carcinoma is divided into two main histological types, type I or endometrioid and type II or non-endometrioid, each of which have characteristic, although not exclusive, molecular alterations and mutational profiles. Nevertheless, information about the implication and relevance of some of these genes in this disease is lacking. We sought here to identify new recurrently mutated genes in endometrioid cancers that play a role in tumourigenesis and that influence the clinical outcome. We focused on low-grade, non-ultramutated tumours as these tumours have a worse prognosis than the ultramutated POLE-positive endometrioid endometrial carcinomas (EECs). We performed exome-sequencing of 11 EECs with matched normal tissue and subsequently validated 15 candidate genes in 76 samples. For the first time, we show that mutations in chromatin remodelling-related genes (KMT2D, KMT2C, SETD1B and BCOR) and in DNA-repair-related genes (BRCA1, BRCA2, RAD50 and CHD4) are frequent in this subtype of endometrial cancer. The alterations to these genes occurred with frequencies ranging from 35.5% for KMT2D to 10.5% for BRCA1 and BCOR, with some showing a tendency toward co-occurrence (RAD50-KMT2D and RAD50-SETD1B). All these genes harboured specific mutational hotspots. In addition, the mutational status of KMT2C, KMT2D and SETD1B helps to predict the degree of myometrial invasion, a critical prognostic feature. These results highlight the possible implication of these genes in this disease, creating opportunities for new therapeutic approaches.

Polymerase ε (POLE) ultra-mutation in uterine tumors correlates with T lymphocyte infiltration and increased resistance to platinum-based chemotherapy in vitro

OBJECTIVE

Up to 12% of all endometrial-carcinomas (EC) harbor DNA-polymerase-ε-(POLE) mutations. It is currently unknown whether the favorable prognosis of POLE-mutated EC is derived from their low metastatic capability, extraordinary number of somatic mutations thus imparting immunogenicity, or a high sensitivity to chemotherapy.

METHODS

Polymerase-chain-reaction-amplification and Sanger-sequencing were used to test for POLE exonuclease-domain-mutations (exons 9-14) 131 EC. Infiltration of CD4+ and CD8+ T-lymphocytes (TIL) and PD-1-expression in POLE-mutated vs POLE wild-type EC was studied by immunohistochemistry (IHC) and the correlations between survival and molecular features were investigated. Finally, primary POLE-mutated and POLE-wild-type EC cell lines were established and compared in-vitro for their sensitivity to chemotherapy.

RESULTS

Eleven POLE-mutated EC (8.5%) were identified. POLE-mutated tumors were associated with improved progression-free-survival (P<0.05) and displayed increased numbers of CD4+ (44.5 vs 21.8; P=0.001) and CD8+ (32.8 vs 13.5; P<0.001) TILs when compared to wild-type POLE EC. PD-1 receptor was overexpressed in TILs from POLE-mutated vs wild-type-tumors (81% vs 28%; P<0.001). Primary POLE tumor cell lines were significantly more resistant to platinum-chemotherapy in-vitro when compared to POLE-wild-type tumors (P<0.004).

CONCLUSIONS

POLE ultra-mutated EC are heavily infiltrated with CD4+/CD8+ TIL, overexpress PD-1 immune-check-point (i.e., features consistent with chronic antigen-exposure), and have a better prognosis when compared to other molecular subtypes of EC patients. POLE-mutated tumor-cell lines are resistant to platinum-chemotherapy in-vitro suggesting that the better prognosis of POLE-patients is not secondary to a higher sensitivity to chemotherapy but likely linked to enhanced immunogenicity.

Cancer predisposition syndromes: lessons for truly precision medicine

Cancer predisposition syndromes are typically uncommon, monogenic, high-penetrance disorders. Despite their rarity, they have proven to be highly clinically relevant in directing cancer prevention strategies. As such, they share notable similarities with an expanding class of low-frequency somatic mutations that are associated with a striking prognostic or predictive effect in the tumours in which they occur. In this review, we highlight these commonalities, with particular reference to mutations in the proofreading domain of replicative DNA polymerases. These molecular phenotypes may occur as either germline or somatic events, and in the latter case, have been shown to confer a favourable prognosis and potential increased benefit from immune checkpoint inhibition. We note that incorporation of these variants into clinical management algorithms will help refine patient management, and that this will be further improved by the inclusion of other germline variants, such as those that determine the likelihood of benefit or toxicity from anti-neoplastic therapy. Finally, we propose that such integrated patient and tumour profiling will be essential if we are to deliver truly precision medicine for cancer patients, but in a similar way to rare germline mutations, we must ensure that we identify and utilize rare somatic mutations with strong predictive and prognostic effects. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Molecular approaches for classifying endometrial carcinoma

Endometrial carcinoma is the most common cancer of the female genital tract. This review article discusses the usefulness of molecular techniques to classify endometrial carcinoma. Any proposal for molecular classification of neoplasms should integrate morphological features of the tumors. For that reason, we start with the current histological classification of endometrial carcinoma, by discussing the correlation between genotype and phenotype, and the most significant recent improvements. Then, we comment on some of the possible flaws of this classification, by discussing also the value of molecular pathology in improving them, including interobserver variation in pathologic interpretation of high grade tumors. Third, we discuss the importance of applying TCGA molecular approach to clinical practice. We also comment on the impact of intratumor heterogeneity in classification, and finally, we will discuss briefly, the usefulness of TCGA classification in tailoring immunotherapy in endometrial cancer patients. We suggest combining pathologic classification and the surrogate TCGA molecular classification for high-grade endometrial carcinomas, as an option to improve assessment of prognosis.

Predicted neoantigen load in non-hypermutated endometrial cancers: Correlation with outcome and tumor-specific genomic alterations

Elevated neoantigen load has been previously correlated with improved outcome and response to immune checkpoint blockade in various tumor types. In endometrial cancer, previous studies of neoantigen load prediction have shown that the hypermutated MSI and POLE-mutated tumors harbor significantly higher predicted neoantigen load compared to the hypomutated CN-low/endometrioid and CN-high/serous-like tumors. Here, we report that predicted neoantigen load may be a prognostic factor in hypomutated endometrial cancers, both in CN-low/endometrioid and CN-high/serous-like tumors. Specifically, in the TCGA dataset, CN-low/endometrioid tumors with neoantigen load in the highest tertile were associated with significantly improved progression free survival (PFS) (p = 0.031), while CN-high/serous-like tumors with neoantigen load in the lowest tertile were associated with worse PFS (p = 0.041). Importantly, certain tumor-specific genomic alterations were enriched in tumors with lower neoantigen load, including CTNNB1 mutations in CN-low/endometrioid tumors and MYC amplification and PIK3CA mutations in CN-high/serous-like tumors. These findings suggest that predicted neoantigen load and specific genomic alterations (such as CTNNB1 mutations, MYC amplification and PIK3CA mutations) may be biomarkers of response to immunotherapy in hypomutated endometrial cancers, and argues that these exploratory biomarkers should be incorporated in clinical trials of immune checkpoint blockade in this disease.

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Neoantigen load is associated with outcome in hypomutated endometrial cancers.

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CTNNB1 mutations are enriched in CN-low/endometrioid tumors with low neoantigen load.

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MYC amplification and PIK3CA mutations are enriched in CN-high/serous-like tumors with low neoantigen load.

New classification of endometrial cancers: the development and potential applications of genomic-based classification in research and clinical care

Endometrial carcinoma (EC) is the fourth most common cancer in women in the developed world. Classification of ECs by histomorphologic criteria has limited reproducibility and better tools are needed to distinguish these tumors and enable a subtype-specific approach to research and clinical care. Based on the Cancer Genome Atlas, two research teams have developed pragmatic molecular classifiers that identify four prognostically distinct molecular subgroups. These methods can be applied to diagnostic specimens (e.g., endometrial biopsy) with the potential to completely change the current risk stratification systems and enable earlier informed decision making. The evolution of genomic classification in ECs is shared herein, as well as potential applications and discussion of the essential research still needed in order to optimally integrate molecular classification in to current standard of care.

Immunological profiling of molecularly classified high-risk endometrial cancers identifies POLE-mutant and microsatellite unstable carcinomas as candidates for checkpoint inhibition

High-risk endometrial cancer (EC) is an aggressive disease for which new therapeutic options are needed. Aims of this study were to validate the enhanced immune response in highly mutated ECs and to explore immune profiles in other EC subgroups. We evaluated immune infiltration in 116 high-risk ECs from the TransPORTEC consortium, previously classified into four molecular subtypes: (i) ultramutated POLE exonuclease domain-mutant ECs (POLE-mutant); (ii) hypermutated microsatellite unstable (MSI); (iii) p53-mutant; and (iv) no specific molecular profile (NSMP). Within The Cancer Genome Atlas (TCGA) EC cohort, significantly higher numbers of predicted neoantigens were demonstrated in POLE-mutant and MSI tumors compared with NSMP and p53-mutants. This was reflected by enhanced immune expression and infiltration in POLE-mutant and MSI tumors in both the TCGA cohort (mRNA expression) and the TransPORTEC cohort (immunohistochemistry) with high infiltration of CD8⁺ (90% and 69%), PD-1⁺ (73% and 69%) and PD-L1⁺ immune cells (100% and 71%). Notably, a subset of p53-mutant and NSMP cancers was characterized by signs of an antitumor immune response (43% and 31% of tumors with high infiltration of CD8⁺ cells, respectively), despite a low number of predicted neoantigens. In conclusion, the presence of enhanced immune infiltration, particularly high numbers of PD-1 and PD-L1 positive cells, in highly mutated, neoantigen-rich POLE-mutant and MSI endometrial tumors suggests sensitivity to immune checkpoint inhibitors.

Somatic POLE proofreading domain mutation, immune response, and prognosis in colorectal cancer: a retrospective, pooled biomarker study

BACKGROUND

Precision cancer medicine depends on defining distinct tumour subgroups using biomarkers that may occur at very modest frequencies. One such subgroup comprises patients with exceptionally mutated (ultramutated) cancers caused by mutations that impair DNA polymerase epsilon (POLE) proofreading.

METHODS

We examined the association of POLE proofreading domain mutation with clinicopathological variables and immune response in colorectal cancers from clinical trials (VICTOR, QUASAR2, and PETACC-3) and colorectal cancer cohorts (Leiden University Medical Centre 1 and 2, Oslo 1 and 2, Bern, AMC-AJCC-II, and Epicolon-1). We subsequently investigated its association with prognosis in stage II/III colorectal cancer by Cox regression of pooled individual patient data from more than 4500 cases from these studies.

FINDINGS

Pathogenic somatic POLE mutations were detected in 66 (1·0%) of 6517 colorectal cancers, and were mutually exclusive with mismatch repair deficiency (MMR-D) in the 6277 cases for whom both markers were determined (none of 66 vs 833 [13·4%] of 6211; p<0·0001). Compared with cases with wild-type POLE, cases with POLE mutations were younger at diagnosis (median 54·5 years vs 67·2 years; p<0·0001), were more frequently male (50 [75·8%] of 66 vs 3577 [55·5%] of 6445; p=0·0010), more frequently had right-sided tumour location (44 [68·8%] of 64 vs 2463 [39·8%] of 6193; p<0·0001), and were diagnosed at an earlier disease stage (p=0·006, χ2 test for trend). Compared with mismatch repair proficient (MMR-P) POLE wild-type tumours, POLE-mutant colorectal cancers displayed increased CD8+ lymphocyte infiltration and expression of cytotoxic T-cell markers and effector cytokines, similar in extent to that observed in immunogenic MMR-D cancers. Both POLE mutation and MMR-D were associated with significantly reduced risk of recurrence compared with MMR-P colorectal cancers in multivariable analysis (HR 0·34 [95% CI 0·11-0·76]; p=0·0060 and 0·72 [0·60-0·87]; p=0·00035), although the difference between the groups was not significant.

INTERPRETATION

POLE proofreading domain mutations identify a subset of immunogenic colorectal cancers with excellent prognosis. This association underscores the importance of rare biomarkers in precision cancer medicine, but also raises important questions about how to identify and implement them in practice.

FUNDING

Cancer Research UK, Academy of Medical Sciences, Health Foundation, EU, ERC, NIHR, Wellcome Trust, Dutch Cancer Society, Dutch Digestive Foundation.

Genetic predisposition to colorectal cancer: Implications for treatment and prevention

Colorectal cancer (CRC) is the third most common cancer diagnosed in men and women and approximately 5% of cases are associated with identifiable germline mutations associated with hereditary cancer syndromes. Lifetime risks for CRC can approach 50%-80% for mutation carriers in the absence of endoscopic and/or surgical intervention, and early identification of at-risk individuals can guide clinical interventions for cancer prevention and treatment. Personal and family history and molecular phenotype of CRC tumors are used in determining which patients should be referred for clinical genetic evaluation. Outcomes of genetic testing performed using next-generation sequencing (NGS) multigene panels suggest there can be significant overlap in clinical features among the various hereditary cancer syndromes. This review summarizes new developments in diagnosis and management of patients with genetic predisposition to CRC.

Important molecular genetic markers of colorectal cancer

Colorectal cancer (CRC) ranks third in the incidences of cancer morbidity and mortality worldwide. CRC is rather heterogeneous with regard to molecular genetic characteristics and pathogenic pathways. A wide spectrum of biomarkers is used for molecular subtype determination, prognosis, and estimation of sensitivity to different drugs in practice. These biomarkers can include germline and somatic mutations, chromosomal aberrations, genomic abnormalities, gene expression alterations at mRNA or protein level and changes in DNA methylation status. In the present review we discuss the most important and well-studied CRC biomarkers, and their potential clinical significance and current approaches to molecular classification of colorectal tumors.

Rare cancers: a sea of opportunity

Rare cancers, as a collective, account for around a quarter of all cancer diagnoses and deaths. Historically, they have been divided into two groups: cancers defined by their unusual histogenesis (cell of origin or differentiation state)--including chordomas or adult granulosa cell tumours--and histologically defined subtypes of common cancers. Most tumour types in the first group are still clinically and biologically relevant, and have been disproportionately important as sources of insight into cancer biology. By contrast, most of those in the second group have been shown to have neither defining molecular features nor clinical utility. Omics-based analyses have splintered common cancers into a myriad of molecularly, rather than histologically, defined subsets of common cancers, many of which have immediate clinical relevance. Now, almost all rare cancers are either histomolecular entities, which often have pathognomonic mutations, or molecularly defined subsets of more common cancers. The presence of specific genetic variants provides rationale for the testing of targeted drugs in rare cancers. However, in addition to molecular alterations, it is crucial to consider the contributions of both mutation and cell context in the development, biology, and behaviour of these cancers. Patients with rare cancers are disadvantaged because of the challenge of leading clinical trials in this setting due to poor accrual. However, the number of patients with rare cancers will only increase as more molecular subsets of common cancers are identified, necessitating a shift in the focus of clinical trials and research into these cancer types, which, by epidemiological definitions, will become rare tumours.

CD8 down-regulation on cytotoxic T lymphocytes of patients with endometrioid endometrial carcinomas

Carcinogenesis is a multistep process in which cancer cells and tumor stroma cells play important roles. T lymphocytes are immune constituents of tumor stroma and play a crucial function in anti-tumor response. By immunohistochemistry and flow cytometry, we studied T cytotoxic (CTLs) and T helper lymphocyte distribution and percentage in the tumor microenvironment and peripheral blood from 35 patients with endometrioid endometrial carcinomas (EEC). We also studied 23 healthy donors' blood samples as a control group. Tumor and non-tumoral endometrium samples were obtained. Immunohistochemistry revealed a high number of CTLs and T helper lymphocytes in the tumor stroma of myoinvasive EECs. T lymphocytes were mostly located in the invasive front. By flow cytometry, the percentages of CTLs and T helper lymphocytes were significantly higher in the tumor compared with the non-neoplastic endometrium (P = .0492 and P = .002). The mean fluorescence intensity of CD8 staining was lower in the tumor compared to the non-neoplastic endometrium (P = .001). There was also reduction of the mean fluorescence intensity of CD8 staining on peripheral blood from patients with grade 3 EECs compare to the peripheral blood from healthy donors (P = .0093). No alterations in the expression of granzymes A and B were found in the CTLs from the EEC cases. Finally, in a proteome profiler cytokine array we found that the growth differentiation factor 15 (GDF15) increased in blood in parallel to the tumor grade. EECs are capable of down-regulating CD8 expression of CTLs. Most likely, this effect is mediated by a soluble molecule present in plasma and is not a result of anergy or exhaustion state.

Tumor genotype and immune microenvironment in POLE-ultramutated and MSI-hypermutated Endometrial Cancers: New candidates for checkpoint blockade immunotherapy?

Endometrial Cancer (EC) is still a challenge for gynecological oncologists because the treatment of the advanced disease remains an unmet need for patients. The Cancer Genome Atlas Research Network (TCGA) recently provided a comprehensive genomic and transcriptomic analysis of EC, offering a new classification of the disease, based on genetic features, which defines four subgroups of cancer rather than the two traditionally recognized. In the molecular classification two types of EC, the polymerase epsilon (POLE)-ultramutated and the microsatellite instability (MSI)-hypermutated, seem to present an enhanced immune microenvironment and a high mutation burden. The blockade of the immune checkpoints is an innovative approach that has largely demonstrated to be effective in solid malignancies, such as lung, renal and melanoma; it acts by reducing the cancer-induced immune-suppression through inhibition of the PD-1/PD-L1 (Programmed Death and PD-Ligand) axis. All available evidence supporting an over-expression of the PD-1/PD-L1 pathway in EC has been reviewed. In particular in the POLE and MSI ECs an up-regulation of this pathway was found, aiming to suggest a rationale for testing the PD-1/PD-L1 immunotherapy in these cancer subgroups.

Increased incidence of FBXW7 and POLE proofreading domain mutations in young adult colorectal cancers

BACKGROUND

The incidence and outcomes of patients with colorectal cancer (CRC) varies by age. Younger patients tend to have sporadic cancers that are not detected by screening and worse survival. To understand whether genetic differences exist between age cohorts, the authors sought to characterize unique genetic alterations in patients with CRC.

METHODS

In total, 283 patients who were diagnosed with sporadic CRC between 1998 and 2010 were identified and divided by age into 2 cohorts-ages ≤45 years (the younger cohort) and ≥65 years (the older cohort)-and targeted exome sequencing was performed. The Fisher exact test was used to detect differences in mutation frequencies between the 2 groups. Whole exome sequencing was performed on 21 additional younger patient samples for validation. Findings were confirmed in The Cancer Genome Atlas CRC data set.

RESULTS

In total, 246 samples were included for final analysis (195 from the older cohort and 51 from the younger cohort). Mutations in the FBXW7 gene were more common in the younger cohort (27.5% vs 9.7%; P = .0022) as were mutations in the proofreading domain of polymerase ε catalytic subunit (POLE) (9.8% vs 1%; P = .0048). There were similar mutation rates between cohorts with regard to TP53 (64.7% vs 61.5%), KRAS (43.1% vs 46.2%), and APC (60.8% vs 73.8%). BRAF mutations were numerically more common in the older cohort, although the difference did not reach statistical significance (2% vs 9.7%; P = .082).

CONCLUSIONS

In this retrospective study, a unique genetic profile was identified for younger patients who have CRC compared with patients who are diagnosed at an older age. These findings should be validated in a larger study and could have an impact on future screening and treatment modalities for younger patients with CRC. Cancer 2016. © 2016 American Cancer Society. Cancer 2016;122:2828-2835. © 2016 American Cancer Society.

SLUG expression is an indicator of tumour recurrence in high-grade endometrial carcinomas

AIMS

To investigate how SNAIL and SLUG were involved in the nature of high-grade endometrial carcinomas (grade 3 endometrioid carcinoma, serous carcinoma and clear cell carcinoma), we analysed the correlation of their expression status with clinicopathological characteristics and evaluated their prognostic significance.

METHODS AND RESULTS

We performed immunohistochemical staining in 52 high-grade endometrial carcinomas. Expression status of SNAIL and SLUG was classified into a high expression (positive in more than 50% of the tumour cells) and a low expression. Thirteen cases (25%) showed a high expression of SLUG, whereas all 52 cases showed a low expression of SNAIL. High expression of SLUG was correlated significantly with tumour recurrence (P = 0.0203) and aberrant p53 expression (P = 0.000559). Overall survival was worse in patients with high SLUG expression at all stages (P = 0.0327) and in those who underwent adjuvant therapy (P = 0.00963). Among the patients with complete tumour resection, high SLUG expression was associated with worse recurrence-free survival (RFS) in the patients at all stages (P = 0.00264), at stages III/IV (P = 0.0146), and who underwent adjuvant therapy (P = 0.000743). SLUG expression was identified as an independent factor of RFS by multivariate analysis (hazard ratio 5.938, 95% confidence interval 1.251-28.18, P = 0.025).

CONCLUSIONS

SLUG expression could be correlated with TP53 mutational status and could be involved in therapeutic resistance resulting in tumour recurrence. A high expression level of SLUG can be an indicator of recurrence and a therapeutic target for long-term remission in high-grade endometrial carcinomas.

Molecular Analysis of Mixed Endometrial Carcinomas Shows Clonality in Most Cases

Mixed endometrial carcinoma refers to a tumor that comprises 2 or more distinct histotypes. We studied 18 mixed-type endometrial carcinomas-11 mixed serous and low-grade endometrioid carcinomas (SC/EC), 5 mixed clear cell and low-grade ECs (CCC/EC), and 2 mixed CCC and SCs (CCC/SC), using targeted next-generation sequencing and immunohistochemistry to compare the molecular profiles of the different histotypes present in each case. In 16 of 18 cases there was molecular evidence that both components shared a clonal origin. Eight cases (6 EC/SC, 1 EC/CCC, and 1 SC/CCC) showed an SC molecular profile that was the same in both components. Five cases (3 CCC/EC and 2 SC/EC) showed a shared endometrioid molecular profile and identical mismatch-repair protein deficiency in both components. A single SC/EC case harbored the same POLE exonuclease domain mutation in both components. One SC/CCC and 1 EC/CCC case showed both shared and unique molecular features in the 2 histotype components, suggesting early molecular divergence from a common clonal origin. In 2 cases, there were no shared molecular features, and these appear to be biologically unrelated synchronous tumors. Overall, these results show that the different histologic components in mixed endometrial carcinomas typically share the same molecular aberrations. Mixed endometrial carcinomas most commonly occur through morphologic mimicry, whereby tumors with serous-type molecular profile show morphologic features of EC or CCC, or through underlying deficiency in DNA nucleotide repair, with resulting rapid accrual of mutations and intratumoral phenotypic heterogeneity. Less commonly, mixed endometrial carcinomas are the result of early molecular divergence from a common progenitor clone or are synchronous biologically unrelated tumors (collision tumors).

Reducing Overtreatment in Gynecologic Oncology: The Case for Less in Endometrial and Ovarian Cancer

A growing awareness of the harms of overtreatment in cancer care has reached physicians, patients, health policy makers, and medical researchers. Overtreatment exposes patients to the risk of adverse events from procedures or medications that were not necessary. This review examines common practices in gynecologic malignancies that are unlikely to produce direct benefit to patients with these malignancies, but are likely to produce harms. Specifically, we will explore the utility of lymphadenectomy and adjuvant radiation for women with early-stage endometrial cancer; and screening for recurrence and continuous chemotherapy for advanced-stage ovarian cancer patients.

Progesterone receptor expression is associated with longer overall survival within high-grade histotypes of endometrial carcinoma: A Canadian high risk endometrial cancer consortium (CHREC) study

OBJECTIVE

To assess the association of hormone receptor expression with outcome in high-grade endometrial carcinomas.

METHODS

This study included three sites participating in the Canadian High Risk Endometrial Cancer (CHREC) consortium. Sections from tissue microarrays containing cases with a diagnosis of endometrioid grade 3 (EC3) and endometrial serous carcinoma (ESC) were assessed for estrogen (ER) and progesterone receptor (PR) expression by immunohistochemistry. Expression was considered present if >1% of tumor cell nuclei were labeled. Associations with overall survival were assessed.

RESULTS

ER expression was present in 168/216 (78%) of EC3 and 124/192 (65%) of ESC. PR expression was present in 148/212 (70%) of EC3 and 83/196 (42%) of ESC. PR expression was significantly associated with favorable overall survival in EC3 and ESC (log rank, p=0.018 and p=0.0024) but ER expression was not. PR expression was significantly associated with favorable overall survival in EC3 independent of age, stage, center and lymph-vascular invasion (hazard ratio=0.457, 95% CI 0.257-0.811, p=0.0075) as well as in stage I and II ESC (hazard ratio=0.266, 95% CI 0.094-0.750, p=0.0123).

CONCLUSION

Our data provide support for the assessment of the PR expression status in EC3 and ESC. Future work will be required to determine how PR expression may be incorporated into management of patients with EC3 and ESC.

Improved Risk Assessment by Integrating Molecular and Clinicopathological Factors in Early-stage Endometrial Cancer-Combined Analysis of the PORTEC Cohorts

PURPOSE

Recommendations for adjuvant treatment for women with early-stage endometrial carcinoma are based on clinicopathologic features. Comprehensive genomic characterization defined four subgroups: p53-mutant, microsatellite instability (MSI), POLE-mutant, and no specific molecular profile (NSMP). We aimed to confirm the prognostic capacity of these subgroups in large randomized trial populations, investigate potential other prognostic classifiers, and integrate these into an integrated molecular risk assessment guiding adjuvant therapy.

EXPERIMENTAL DESIGN

Analysis of MSI, hotspot mutations in 14 genes including POLE, protein expression of p53, ARID1a, β-catenin, L1CAM, PTEN, ER, and PR was undertaken on 947 available early-stage endometrioid endometrial carcinomas from the PORTEC-1 and -2 trials, mostly high-intermediate risk (n = 614). Prognostic value was determined using univariable and multivariable Cox proportional hazard models. AUCs of different risk stratification models were compared.

RESULTS

Molecular analyses were feasible in >96% of the patients and confirmed the four molecular subgroups: p53-mutant (9%), MSI (26%), POLE-mutant (6%), and NSMP (59%). Integration of prognostic molecular alterations with established clinicopathologic factors resulted in a stronger model with improved risk prognostication. Approximately 15% of high-intermediate risk patients had unfavorable features (substantial lymphovascular space invasion, p53-mutant, and/or >10% L1CAM), 50% favorable features (POLE-mutant, NSMP being microsatellite stable, and CTNNB1 wild-type), and 35% intermediate features (MSI or CTNNB1-mutant).

CONCLUSIONS

Integrating clinicopathologic and molecular factors improves the risk assessment of patients with early-stage endometrial carcinoma. Assessment of this integrated risk profile is feasible in daily practice, and holds promise to reduce both overtreatment and undertreatment. Clin Cancer Res; 22(16); 4215-24. ©2016 AACR.

Loss of switch/sucrose non-fermenting complex protein expression is associated with dedifferentiation in endometrial carcinomas

Dedifferentiated endometrial carcinoma is an aggressive type of endometrial cancer that contains a mix of low-grade endometrioid and undifferentiated carcinoma components. We performed targeted sequencing of eight dedifferentiated carcinomas and identified somatic frameshift/nonsense mutations in SMARCA4, a core ATPase of the switch/sucrose non-fermenting (SWI/SNF) complex, in the undifferentiated components of four tumors. Immunohistochemical analysis confirmed the loss of SMARCA4 in the undifferentiated component of these four SMARCA4-mutated cases, whereas the corresponding low-grade endometrioid component showed retained SMARCA4 expression. An expanded survey of other members of the SWI/SNF complex showed SMARCB1 loss in the undifferentiated component of two SMARCA4-intact tumors, and all SMARCA4- or SMARCB1-deficient tumors showed concomitant loss of expression of SMARCA2. We subsequently examined the expression of SMARCA2, SMARCA4, and SMARCB1 in an additional set of 22 centrally reviewed dedifferentiated carcinomas and 31 grade 3 endometrioid carcinomas. Combining the results from the index and the expansion set, 15 of 30 (50%) of the dedifferentiated carcinomas examined showed either concurrent SMARCA4 and SMARCA2 loss (37%) or concurrent SMARCB1 and SMARCA2 loss (13%) in the undifferentiated component. The loss of SMARCA4 or SMARCB1 was mutually exclusive. All 31 grade 3 endometrioid carcinomas showed intact expression of these core SWI/SNF proteins. The majority (73%) of the SMARCA4/SMARCA2-deficient and half of SMARCB1/SMARCA2-deficient undifferentiated component developed in a mismatch repair-deficient molecular context. The observed spatial association between SWI/SNF protein loss and histologic dedifferentiation suggests that inactivation of these core SWI/SNF proteins may contribute to the development of dedifferentiated endometrial carcinoma.

Mechanisms and Consequences of Cancer Genome Instability: Lessons from Genome Sequencing Studies

During tumor evolution, cancer cells can accumulate numerous genetic alterations, ranging from single nucleotide mutations to whole-chromosomal changes. Although a great deal of progress has been made in the past decades in characterizing genomic alterations, recent cancer genome sequencing studies have provided a wealth of information on the detailed molecular profiles of such alterations in various types of cancers. Here, we review our current understanding of the mechanisms and consequences of cancer genome instability, focusing on the findings uncovered through analysis of exome and whole-genome sequencing data. These analyses have shown that most cancers have evidence of genome instability, and the degree of instability is variable within and between cancer types. Importantly, we describe some recent evidence supporting the idea that chromosomal instability could be a major driving force in tumorigenesis and cancer evolution, actively shaping the genomes of cancer cells to maximize their survival advantage.

Prognostic significance of L1CAM expression and its association with mutant p53 expression in high-risk endometrial cancer

Studies in early-stage, predominantly low- and intermediate-risk endometrial cancer have demonstrated that L1 cell adhesion molecule (L1CAM) overexpression identifies patients at increased risk of recurrence, yet its prognostic significance in high-risk endometrial cancer is unclear. To evaluate this, its frequency, and the relationship of L1CAM with the established endometrial cancer biomarker p53, we analyzed the expression of both markers by immunohistochemistry in a pilot series of 116 endometrial cancers (86 endometrioid, 30 non-endometrioid subtype) with high-risk features (such as high tumor grade and deep myometrial invasion) and correlated results with clinical outcome. We used The Cancer Genome Atlas (TCGA) endometrial cancer series to validate our findings. Using the previously reported cutoff of 10% positive staining, 51/116 (44%) tumors were classified as L1CAM-positive, with no significant association between L1CAM positivity and the rate of distant metastasis (P=0.195). However, increasing the threshold for L1CAM positivity to 50% resulted in a reduction of the frequency of L1CAM-positive tumors to 24% (28/116), and a significant association with the rate of distant metastasis (P=0.018). L1CAM expression was strongly associated with mutant p53 in the high-risk and TCGA series (P<0.001), although a substantial fraction (36% of endometrioid, 10% of non-endometrioid morphology) of p53-mutant endometrial cancers displayed <10% L1CAM positivity. Moreover, 30% of p53-wild-type non-endometrioid endometrial cancers demonstrated diffuse L1CAM staining, suggesting p53-independent mechanisms of L1CAM overexpression. In conclusion, the previously proposed threshold for L1CAM positivity of >10% does not predict prognosis in high-risk endometrial cancer, whereas an alternative threshold (>50%) does. L1CAM expression is strongly, but not universally, associated with mutant p53, and may be strong enough for clinical implementation as prognostic marker in combination with p53. The high frequency of L1CAM expression in high-risk endometrial cancers suggests that it may also be a promising therapeutic target in this tumor subset.

A panoply of errors: polymerase proofreading domain mutations in cancer

Although it has long been recognized that the exonucleolytic proofreading activity intrinsic to the replicative DNA polymerases Pol δ and Pol ε is essential for faithful replication of DNA, evidence that defective DNA polymerase proofreading contributes to human malignancy has been limited. However, recent studies have shown that germline mutations in the proofreading domains of Pol δ and Pol ε predispose to cancer, and that somatic Pol ε proofreading domain mutations occur in multiple sporadic tumours, where they underlie a phenotype of 'ultramutation' and favourable prognosis. In this Review, we summarize the current understanding of the mechanisms and consequences of polymerase proofreading domain mutations in human malignancies, and highlight the potential utility of these variants as novel cancer biomarkers and therapeutic targets.

Mutation spectrum of POLE and POLD1 mutations in South East Asian women presenting with grade 3 endometrioid endometrial carcinomas

OBJECTIVE

Somatic POLE mutations have been found in a subset of endometrioid ECs particularly in FIGO grade 3 tumors while POLD1 mutations are reportedly rare in ECs. While it has been suggested that POLE mutation confers good prognosis, the data remains conflicting. Our study aims to determine the mutation spectrum of somatic and germline POLE and POLD1 gene mutations in South East Asian (SEA) women with FIGO grade 3 endometrioid ECs.

METHODS

Forty-seven patients diagnosed with FIGO grade 3 endometrioid EC, diagnosed between 2009 and 2013 were included. Next generation sequencing (NGS) using formalin fixed embedded (FFPE) tissue was utilized to sequence tumor and matched normal tissue. Tumors were also assessed for other clinicopathologic and microsatellite status phenotype. Survival curves for pathogenic somatic POLE mutated and wild-type tumors were estimated by Kaplan-Meier method.

RESULTS

Pathogenic POLE (somatic or germline) and POLD1 (germline) mutations were detected in 29.7% (14/47) and 4.3% (2/47) patients, respectively. Three pathogenic germline mutations; one POLE and two POLD1 mutations were novel. Pathogenic germline and somatic POLE and POLD1 mutations were associated with 100% recurrence free survival. In contrast, among the wild-type POLE and POLD1 patients, 25% (8/32) had recurrence with 15.6% (5/32) subsequently dying of the disease. Somatic POLE-mutated tumors were more commonly associated with microsatellite stable (MSS) ECs (83% vs 49%; p=0.04) and peritumoral lymphocytic infiltration (75% vs 42%; p=0.05). All tumors with tumoral infiltrating lymphocytes exhibited peritumoral lymphocytic infiltrate but not vice versa.

CONCLUSION

Mutations in POLE and POLD1 in SEA women with grade 3 endometrioid ECs are associated with improved recurrence free survival. Notably, germline mutations in either POLE/POLD1 were seen in 8.5% of patients who will require appropriate genetic counseling regarding risk of developing colorectal carcinoma and on the need for additional surveillance for colonic changes. MSS and peritumoral lymphocytic infiltration may be useful histological features for distinguishing POLE mutated grade 3 endometrioid ECs.