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

Abstract

Objective The antitumor effects of anti-PD-1 antibody against mismatch repair deficiency (MMR-D)-associated cancers have been reported. MMR-D is found in approximately 20%–30% of endometrial carcinomas (ECs) and frequently occurs due to MLH1 promoter hypermethylation ( MLH1 -PHM). ECs with MLH1 -PHM are classified according to the molecular screening of Lynch syndrome (LS), but few detailed reports are available. The purpose of this study was to clarify the clinical features of EC with MLH1 -PHM. Methods Immunohistochemistry of MMR proteins (MLH1, MSH2, MSH6, and PMS2) was performed on specimens from 527 ECs treated at our university hospital from 2003 to 2018. MLH1 methylation analysis was added to cases with MLH1/PMS2 loss. ECs were classified as follows: cases that retained MMR proteins as “MMR-proficient;” cases with MLH1/PMS2 loss and MLH1 -PHM as “met-EC;” and cases with other MMR protein loss and MLH1/PMS2 loss without MLH1 -PHM as “suspected-LS.” The clinical features, including long-term prognosis, of each group, were analyzed. Results Accordingly, 419 (79.5%), 65 (12.3%), and 43 (8.2%) cases were categorized as “MMR-proficient,” “suspected-LS,” and “met-EC,” respectively. Significantly, “met-EC” had a lower proportion of grade 1 tumors (37.5%) and a higher proportion of stage III/IV tumors (37.2%) than the other groups. The overall and progression-free survival of “met-EC” were significantly worse than those of “suspected-LS” in all cases. Conclusion In ECs with MMR-D, “met-ECs” were a subgroup with a poorer prognosis than “suspected-LS.” “Met-ECs” would be the main target for anti-PD-1 antibody treatment, and its clinical susceptibility should be verified individually.

Noninvasive detection of microsatellite instability in patients with endometrial cancer

“…To validate our approach, the UAs from a total cohort of 90 patients with EC were interrogated using the ddPCR assay, being 64.44% classified as MSI‐H after the analysis. In 8 of the 34 of these MSI‐H tumors we found a genetic cause of the MSI status, being the remaining cases probably associated to epigenetic regulation, in line with the percentages expected of sporadic and Lynch‐associated MSI tumors 34,35 . Importantly, this patients' cohort was enriched in MMR deficient tumors with the purpose to technically validate our analytic approach, therefore, the results obtained should be interpreted taking into account that in a real‐world cohort the rate of MSI tumors will be about the 30% 35 .…”

“…In 8 of the 34 of these MSI-H tumors we found a genetic cause of the MSI status, being the remaining cases probably associated to epigenetic regulation, in line with the percentages expected of sporadic and Lynch-associated MSI tumors. 34,35 Importantly, this patients' cohort was enriched in MMR deficient tumors with the purpose to technically validate our analytic approach, therefore, the results obtained should be interpreted taking into account that in a real-world cohort the rate of MSI tumors will be about the 30%. 35 The cohort is also enriched in high-risk tumors since they have a greater clinical interest as potential future recurrent cases that could be treated and monitored based on our non-invasive approach.…”

Molecular classification of endometrial cancer of Chinese population.

“…Immunohistochemistry (IHC) was performed on 5-µm thick sections of a representative formalin-xed, para n-embedded (FFPE) tumor tissue, which was descripted in the manufacturer's instructions [9]. FFPE tissue sections were rehydrated in xylene and gradient concentration alcohol, and antigens were retrieved by heating the sections in EDTA (pH 9.0) for 15 min at 100°C.…”

“…Endogenous peroxidase activity was blocked with H 2 O 2 and the sections were incubated with primary antibodies diluted 1:100 or 1:200 at 4°C overnight, followed by incubation with secondary antibodies at room temperature for 30min. The sections were stained with 3,3′-diaminobenzidine (DAB) as the chromogen (ZLI-9019, Origene, USC), followed by staining with prediluted anti-MMR/P53 antibody (clone PA0057, Leica, USA) [9][10][11]. The negative control was a matched rabbit IgG.…”

“…The overexpression and complete absence of p53 staining and the cytoplasmic pattern of p53 staining also recognized as a distinct abnormal expression pattern (aberrant/mutation-type). Except for the above, other p53 staining patterns are considered normal/wild type patterns [9][10][11].…”