Epigenetic silencing of MLH1 in endometrial cancers is associated with larger tumor volume, increased rate of lymph node positivity and reduced recurrence-free survival.

To determine the relationship between mismatch repair (MMR) classification and clinicopathologic features including tumor volume, and explore outcomes by MMR class in a contemporary cohort. Single institution cohort evaluating MMR classification for endometrial cancers (EC). MMR immunohistochemistry (IHC)±microsatellite instability (MSI) testing and reflex MLH1 methylation testing was performed. Tumors with MMR abnormalities by IHC or MSI and MLH1 methylation were classified as epigenetic MMR deficiency while those without MLH1 methylation were classified as probable MMR mutations. Clinicopathologic characteristics were analyzed. 466 endometrial cancers were classified; 75% as MMR proficient, 20% epigenetic MMR defects, and 5% as probable MMR mutations. Epigenetic MMR defects were associated with advanced stage, higher grade, presence of lymphovascular space invasion, and older age. MMR class was significantly associated with tumor volume, an association not previously reported. The epigenetic MMR defect tumors median volume was 10,220mm3 compared to 3321mm3 and 2,846mm3, for MMR proficient and probable MMR mutations respectively (P<0.0001). Higher tumor volume was associated with lymph node involvement. Endometrioid EC cases with epigenetic MMR defects had significantly reduced recurrence-free survival (RFS). Among advanced stage (III/IV) endometrioid EC the epigenetic MMR defect group was more likely to recur compared to the MMR proficient group (47.7% vs 3.4%) despite receiving similar adjuvant therapy. In contrast, there was no difference in the number of early stage recurrences for the different MMR classes. MMR testing that includes MLH1 methylation analysis defines a subset of tumors that have worse prognostic features and reduced RFS.

Cosgrove CM ，Cohn DE ，Hampel H ，Frankel WL ，Jones D ，McElroy JP ，Suarez AA ，Zhao W ，Chen W ，Salani R ，Copeland LJ ，O'Malley DM ，Fowler JM ，Yilmaz A ，Chassen AS ，Pearlman R ，Goodfellow PJ ，Backes FJ ... -  《-》

Clinicopathologic characteristics and outcomes of endometrial Cancer patients with mismatch repair deficiency in the era of universal Lynch syndrome screening.

To evaluate clinicopathologic characteristics and survival impact associated with mismatch repair (MMR) deficient subgroups of endometrial cancer (EC) in patients undergoing universal screening for Lynch Syndrome. A retrospective cohort study using a prospectively maintained gynecologic oncology registry of patients who underwent surgery for EC was conducted. All pathology specimens underwent tumor testing using immunohistochemistry for MMR deficiency with reflex MLH1 promotor methylation testing. Tumors were classified as MMR-I (intact MMR expression), MMR-DM (MMR deficient due to MLH1 methylation), and MMR-DU (MMR deficient without MLH1 methylation). Univariate and multivariate analysis performed to determine factors associated with MMR-DM. Progression-free survival (PFS) and overall survival (OS) analyzed by stage and endometrioid subgroup. From 2012 to 2016, 1018 EC patients were identified and screened. Overall, 71.6% were classified as MMR-I, 23.8% MMR-DM, and 4.6% MMR-DU. In comparison to MMR-DU, MMR-DM tumors were associated with older age, postmenopausal status, lymphovascular space invasion, and pure endometrioid histology. Compared to MMR-I, MMR-DM tumors were associated with older age, endometrioid histology, lymphovascular space invasion, and higher grade on multivariable analysis. There was no difference in PFS and OS between the three groups overall. In patients with endometrioid EC, MMR-DM tumors were associated with lower PFS vs. MMR-I (HR:2.51, CI:1.54, 4.10, P < 0.001). This effect persisted for stage I/II endometrioid EC (HR 2.66, CI:1.34, 5.26 p = 0.005). No difference in PFS or OS was noted among stage III/IV endometrioid tumors. MMR deficiency is associated with adverse prognostic factors and worse PFS among endometrioid tumors, particularly in early stage EC. MMR testing outside of LS screening has prognostic value, warranting consideration for inclusion as a biomarker in prospective clinical trials.

Carr C ，Son J ，Yao M ，Priyadarshini A ，Marquard J ，Vargas R ，Michener C ，AlHilli MM ... -  《-》

Combined Microsatellite Instability, MLH1 Methylation Analysis, and Immunohistochemistry for Lynch Syndrome Screening in Endometrial Cancers From GOG210: An NRG Oncology and Gynecologic Oncology Group Study.

The best screening practice for Lynch syndrome (LS) in endometrial cancer (EC) remains unknown. We sought to determine whether tumor microsatellite instability (MSI) typing along with immunohistochemistry (IHC) and MLH1 methylation analysis can help identify women with LS. ECs from GOG210 patients were assessed for MSI, MLH1 methylation, and mismatch repair (MMR) protein expression. Each tumor was classified as having normal MMR, defective MMR associated with MLH1 methylation, or probable MMR mutation (ie, defective MMR but no methylation). Cancer family history and demographic and clinical features were compared for the three groups. Lynch mutation testing was performed for a subset of women. Analysis of 1,002 ECs suggested possible MMR mutation in 11.8% of tumors. The number of patients with a family history suggestive of LS was highest among women whose tumors were classified as probable MMR mutation (P = .001). Lynch mutations were identified in 41% of patient cases classified as probable mutation (21 of 51 tested). One of the MSH6 Lynch mutations was identified in a patient whose tumor had intact MSH6 expression. Age at diagnosis was younger for mutation carriers than noncarriers (54.3 v 62.3 years; P < .01), with five carriers diagnosed at age > 60 years. Combined MSI, methylation, and IHC analysis may prove useful in Lynch screening in EC. Twenty-four percent of mutation carriers presented with ECs at age > 60 years, and one carrier had an MSI-positive tumor with no IHC defect. Restricting Lynch testing to women diagnosed at age < 60 years or to women with IHC defects could result in missing a substantial fraction of genetic disease.

Goodfellow PJ ，Billingsley CC ，Lankes HA ，Ali S ，Cohn DE ，Broaddus RJ ，Ramirez N ，Pritchard CC ，Hampel H ，Chassen AS ，Simmons LV ，Schmidt AP ，Gao F ，Brinton LA ，Backes F ，Landrum LM ，Geller MA ，DiSilvestro PA ，Pearl ML ，Lele SB ，Powell MA ，Zaino RJ ，Mutch D ... -  《-》

Characterization of mismatch-repair/microsatellite instability-discordant endometrial cancers.

Mismatch-repair (MMR)/microsatellite instability (MSI) status has therapeutic implications in endometrial cancer (EC). The authors evaluated the concordance of testing and factors contributing to MMR expression heterogeneity. Six hundred sixty-six ECs were characterized using immunohistochemistry (IHC), MSI testing, and mut-L homolog 1 (MLH1) methylation. Select samples underwent whole-transcriptome analysis and next-generation sequencing. MMR expression of metastatic/recurrent sites was evaluated. MSI testing identified 27.3% of cases as MSI-high (n = 182), MMR IHC identified 25.1% cases as MMR-deficient (n = 167), and 3.8% of cases (n = 25) demonstrated discordant results. A review of IHC staining explained discordant results in 18 cases, revealing subclonal loss of MLH1/Pms 1 homolog 2 (PMS2) (n = 10) and heterogeneous MMR IHC (mut-S homolog 6 [MSH6], n = 7; MLH1/PMS2, n = 1). MSH6-associated Lynch syndrome was diagnosed in three of six cases with heterogeneous expression. Subclonal or heterogeneous cases had a 38.9% recurrence rate (compared with 16.7% in complete MMR-deficient cases and 9% in MMR-proficient cases) and had abnormal MMR IHC results in all metastatic recurrent sites (n = 7). Tumors with subclonal MLH1/PMS2 demonstrated 74 differentially expressed genes (determined using digital spatial transcriptomics) when stratified by MLH1 expression, including many associated with epithelial-mesenchymal transition. Subclonal/heterogeneous MMR IHC cases showed epigenetic loss in 66.7%, germline mutations in 16.7%, and somatic mutations in 16.7%. MMR IHC reported as intact/deficient missed 21% of cases of Lynch syndrome. EC with subclonal/heterogeneous MMR expression demonstrated a high recurrence rate, and metastatic/recurrent sites were MMR-deficient. Transcriptional analysis indicated an increased risk for migration/metastasis, suggesting that clonal MMR deficiency may be a driver for tumor aggressiveness. Reporting MMR IHC only as intact/deficient, without reporting subclonal and heterogeneous staining, misses opportunities for biomarker-directed therapy. Endometrial cancer is the most common gynecologic cancer, and 20%-40% of tumors have a defect in DNA proofreading known as mismatch-repair (MMR) deficiency. These results can be used to guide therapy. Tests for this defect can yield differing results, revealing heterogeneous (mixed) proofreading capabilities. Tumors with discordant testing results and mixed MMR findings can have germline or somatic defects in MMR genes. Cells with deficient DNA proofreading in tumors with mixed MMR findings have DNA expression profiles linked to more aggressive characteristics and cancer spread. These MMR-deficient cells may drive tumor behavior and the risk of spreading cancer.

Riedinger CJ ，Esnakula A ，Haight PJ ，Suarez AA ，Chen W ，Gillespie J ，Villacres A ，Chassen A ，Cohn DE ，Goodfellow PJ ，Cosgrove CM ... -  《-》

Clinicopathologic Significance of Mismatch Repair Defects in Endometrial Cancer: An NRG Oncology/Gynecologic Oncology Group Study.

The clinicopathologic significance of mismatch repair (MMR) defects in endometrioid endometrial cancer (EEC) has not been definitively established. We undertook tumor typing to classify MMR defects to determine if MMR status is prognostic or predictive. Primary EECs from NRG/GOG0210 patients were assessed for microsatellite instability (MSI), MLH1 methylation, and MMR protein expression. Each tumor was assigned to one of four MMR classes: normal, epigenetic defect, probable mutation (MMR defect not attributable to MLH1 methylation), or MSI-low. The relationships between MMR classes and clinicopathologic variables were assessed using contingency table tests and Cox proportional hazard models. A total of 1,024 tumors were assigned to MMR classes. Epigenetic and probable mutations in MMR were significantly associated with higher grade and more frequent lymphovascular space invasion. Epigenetic defects were more common in patients with higher International Federation of Gynecology and Obstetrics stage. Overall, there were no differences in outcomes. Progression-free survival was, however, worse for women whose tumors had epigenetic MMR defects compared with the MMR normal group (hazard ratio, 1.37; P < .05; 95% CI, 1.00 to 1.86). An exploratory analysis of interaction between MMR status and adjuvant therapy showed a trend toward improved progression-free survival for probable MMR mutation cases. MMR defects in EECs are associated with a number of well-established poor prognostic indicators. Women with tumors that had MMR defects were likely to have higher-grade cancers and more frequent lymphovascular space invasion. Surprisingly, outcomes in these patients were similar to patients with MMR normal tumors, suggesting that MMR defects may counteract the effects of negative prognostic factors. Altered immune surveillance of MMR-deficient tumors, and other host/tumor interactions, is likely to determine outcomes for patients with MMR-deficient tumors.

McMeekin DS ，Tritchler DL ，Cohn DE ，Mutch DG ，Lankes HA ，Geller MA ，Powell MA ，Backes FJ ，Landrum LM ，Zaino R ，Broaddus RD ，Ramirez N ，Gao F ，Ali S ，Darcy KM ，Pearl ML ，DiSilvestro PA ，Lele SB ，Goodfellow PJ ... -  《-》