The Correlation of Histopathologic Parameters With Mismatch Repair Protein-deficient Subgroups and MLH1 Methylation in Endometrial Carcinomas.

There are limited data regarding the correlation of clinical and pathologic parameters with mismatch repair (MMR) protein-deficient subgroups and methylation status. In this study, we analyzed the status of MMR proteins in resection specimens of 198 consecutive endometrial carcinomas and the methylation status in tumors with MLH1 and PMS2 deficiency. We, therefore, assessed the correlation of clinical and pathologic parameters with MMR protein-deficient subgroups. Univariate analysis revealed that deeper myometrial invasion and the presence of tumor-associated lymphocytes were more frequently observed in tumors with MMR protein deficiency ( P =0.023 and 0.001, respectively). The multivariate logistic regression analysis revealed that only the presence of tumor-associated lymphocytes was significantly associated with MMR protein deficiency ( P =0.002, odds ratio=2.674, 95% confidence interval=1.418-5.045). We also compared MLH1 and PMS2 deficiency with other protein deficiency regarding clinical and pathologic parameters. Furthermore, we compared MLH1 methylated tumors with MMR protein-deficient nonmethylated tumors regarding clinical and pathologic parameters. MLH1 was methylated in 51 of 54 tumors with MLH1 and PMS2 deficiency. In univariate analysis, a larger tumor size was significantly associated with MLH1 and PMS2 deficiency and with MLH1 methylation ( P =0.004 and 0.005, respectively). The multivariate logistic regression analysis revealed that a larger tumor size was significantly associated with MLH1 and PMS2 deficiency and MLH1 methylation ( P =0.002, odds ratio=14.222, 95% confidence interval=2.560-79.026, P =0.008, odds ratio=22.222, 95% confidence interval=2.220-222.395, respectively). Our results showed a slightly higher rate of MLH1 and PMS2 deficiency (34.3%) than in previous studies. This may likely be due to ethnic differences in frequency of various mutations.

Soylemez T ，Kir G ，Olgun ZC ，Dur SR ，Tosun MI ，Ankarali H ，Demircan B ，Kaya IA ，Karateke A ... -  《-》

PD-L1 Expression in Mismatch Repair-deficient Endometrial Carcinoma and Tumor-associated Immune Cells: Differences Between MLH1 Methylated and Nonmethylated Subgroups.

Mismatch repair (MMR)-deficient endometrial carcinomas show increased programmed cell death-ligand 1 (PD-L1) expression compared with MMR-intact endometrial carcinomas, but there are limited data regarding PD-L1 expression between sporadic and inherited carcinomas exhibiting MMR loss. Most of the studies investigating PD-L1 expression in endometrial carcinoma have used tissue microarrays and did not examine all tumor blocks. In this study, we analyzed the expression of PD-L1 in resection specimens of 176 consecutive endometrial carcinomas using all tumor blocks; we compared PD-L1 expression in MMR-deficient endometrial carcinomas, including the MLH1 and PMS2-loss subgroup, and the other MMR-loss subgroups (MSH2 and MSH6, isolated PMS2, and isolated MSH6), with the MMR-intact subgroup. MLH1 methylation was performed in tumors with MLH1 and PMS2 loss. Tumor cell (TC) and tumor-associated immune cell (IC) PD-L1 positivity with a 1% cutoff was observed in 21% (n=37) and 66.5% (n=117) of cases, respectively, and with a 5% cutoff in 5.1% (n=9) and 39.8% (n=70) of cases, respectively. MMR protein deficiency was a statistically significant parameter associated with IC PD-L1 positivity, with 1% and 5% cutoffs on multivariate analysis [odds ratio (OR)=5.236, 95% confidence interval (CI)=2.075-13.211, P=0.001, and OR=3.702, 95% CI=1.759-7.791, P=0.001, respectively]. The multivariate analysis showed that IC PD-L1 positivity, using both 1% and 5% cutoffs, was significantly associated with the MLH1 and PMS2 loss compared with the MMR protein-intact subgroup (MLH1 and PMS2 loss for 1% cutoff: OR=5.104, 95% CI=1.876-13.881, P=0.001, and for 5% cutoff: OR=3.322, 95% CI=1.540-7.166, P=0.002). Squamous differentiation was an independent predictor for TC PD-L1 positivity, with a 5% cutoff (OR=6.102, 95% CI=1.280-10.096, P=0.026). Larger tumor size was an independent predictive factor for IC PD-L1 positivity with a 1% cutoff (OR=6.757, 95% CI=1.569-29.109, P=0.010). Overall, 48 (92.3%) of 52 MLH1 methylated tumors showed IC PD-L1 positivity with 1% cutoff, and 34 (65.4%) of 52 MLH1 methylated tumors showed IC PD-L1 positivity with 5% cutoff. Our results show a higher rate of IC PD-L1 positivity than in previous studies. This is likely due in part to the use of all tumor blocks. MLH1 and PMS2 loss was an independent predictive factor for IC PD-L1 positivity, with both 1% and 5% cutoffs. Using univariate analysis, we observed decreased disease-free survival for IC PD-L1 positivity ≥5%. Our study results should now be tested and proven in larger cohorts, with longer follow-up data.

Kir G ，Olgun ZC ，Soylemez T ，Aydin A ，Demircan B ，Kaya IA ，McCluggage WG ... -  《-》

Tumor mismatch repair immunohistochemistry and DNA MLH1 methylation testing of patients with endometrial cancer diagnosed at age younger than 60 years optimizes triage for population-level germline mismatch repair gene mutation testing.

Buchanan DD ，Tan YY ，Walsh MD ，Clendenning M ，Metcalf AM ，Ferguson K ，Arnold ST ，Thompson BA ，Lose FA ，Parsons MT ，Walters RJ ，Pearson SA ，Cummings M ，Oehler MK ，Blomfield PB ，Quinn MA ，Kirk JA ，Stewart CJ ，Obermair A ，Young JP ，Webb PM ，Spurdle AB ... -  《-》

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.

Kurpiel B ，Thomas MS ，Mubeen M ，Ring KL ，Modesitt SC ，Moskaluk CA ，Mills AM ... -  《-》

Clinicopathological significance of deficient DNA mismatch repair and MLH1 promoter methylation in endometrioid endometrial carcinoma.

Pasanen A ，Loukovaara M ，Bützow R 《-》