Comparison of breast and gastric HER2 immunohistochemistry (IHC) scoring criteria in the assessment of endometrial carcinoma.

HER2 overexpression and amplification occur in a subset of endometrial serous carcinomas (ESC) and carcinosarcomas, but HER2 testing remains unsettled due to the lack of tumor-specific guidelines. We retrospectively evaluated 113 tumors with serous morphology (95 ESC, 4 mixed carcinomas, 13 carcinosarcomas) diagnosed between 2001 and 2022 at two tertiary centers. HER2 immunohistochemistry was assessed using four scoring systems: ASCO/CAP 2007 breast, ASCO/CAP 2023 breast, ASCO/CAP/ASCP 2016 gastric, and an ESC-specific algorithm. All equivocal and discordant cases underwent in situ hybridization (ISH). HER2 positivity ranged from 15% with the 2007 breast and ESC-specific systems to 20% with the 2023 breast and 24% with the gastric criteria, and it was significantly associated with patient age > 70years (p = 0.016). Concordance was excellent between the 2007 breast and ESC-specific systems (K = 0.98), good between the 2023 breast and 2007/ESC systems (K = 0.71-0.73), and excellent between the 2023 breast and gastric criteria (K = 0.95). Eight discordant tumors were resolved by ISH, confirming ERBB2 amplification in five. Intratumoral heterogeneity was observed in 13 cases (12%), including one carcinosarcoma with focal gene amplification. The prevalence of HER2-low tumors varied markedly, from 16 (14%) with gastric criteria to 26 (23%) with ESC-specific scoring. These findings demonstrate that the choice of scoring system substantially impacts HER2 classification in ESC. While 2007 breast and ESC-specific criteria remain the only ones validated for trastuzumab, gastric criteria are required for trastuzumab-deruxtecan eligibility. Standardized, therapy-specific algorithms integrating IHC and ISH are essential to optimize patient selection, including candidates with HER2-low tumors.

Expression of a novel oncofetal mRNA-binding protein IMP3 in endometrial carcinomas: diagnostic significance and clinicopathologic correlations

BackgroundIt is unclear whether uterine carcinosarcoma (UCS) is more aggressive than endometrial serous carcinoma (SC) and clear cell carcinoma (CCC).ObjectivesTo compare the prognosis of UCS to that of endometrial SC and CCC, through a systematic review and meta‐analysis.MethodsFour electronic databases were searched from January 2000 to October 2020. All studies assessing hazard ratio (HR) for death in UCS vs SC and/or CCC. HRs for death with 95% confidence interval were extracted and pooled by using a random‐effect model. A significant P‐value <0.05 was adopted.ResultsSix studies with 11 029 patients (4995 with UCS, 4634 with SC, 1346 with CCC and 54 with either SC or CCC) were included. UCS showed a significantly worse prognosis than SC/CCC both overall (HR = 1.51; P = 0.008) and at early stage (HR = 1.58; P < 0.001). Similar results were found for UCS vs SC (HR = 1.53; P < 0.001) and UCS vs CCC (HR = 1.60; P < 0.001).ConclusionsCompared to SC and CCC, UCS has a significantly worse prognosis, with a 1.5–1.6‐fold increased risk of death. This might justify a more aggressive treatment for UCS compared to SC and CCC. Further studies are necessary to define the prognostic impact of different molecular subgroups.

Competing endogenous RNA (ceRNA) network is dysregulated in the initiation and progression of tumors. In the present study, we explored the regulatory mechanism of ceRNA in endometrial carcinoma (EC) and the potential key molecules with potential value in the diagnosis, treatment, and prognosis of EC. The long noncoding RNAs (lncRNAs) and messenger RNAs (mRNAs) expression profiles (552 EC tissues and 35 nontumor tissues) and microRNAs (miRNAs) expression profiles (546 EC tissues and 33 nontumor tissues) were downloaded from The Cancer Genome Atlas database to identify differentially expressed RNAs (DERNAs) in EC. An integrated bioinformatics analysis was used to construct an EC-specific ceRNA network and select key molecules. As a result, 96 differentially expressed lncRNAs (DElncRNAs), 29 differentially expressed miRNAs (DEmiRNAs), and 77 differentially expressed mRNAs (DEmRNAs) were identified. An EC-specific ceRNA network was built based on nine DElncRNAs significantly associated with overall survival. CCNB1 was found as a key gene in EC through the weighted gene coexpression network analysis and protein-protein interaction network analysis. Our ceRNA network showed C2orf48 and LINC00483 might upregulate CCNB1 via competing with miR-183. In addition, we found a subnetwork which contained survival-associated DERNAs (AC110491.1, LINC00483-miR-192-GRHL1). The results of reverse transcription quantitative polymerase chain reaction supported the relative expressions of C2orf48, LINC00483 were upregulated and that of AC110491.1 was downregulated in EC. We further found C2orf48 was upregulated in serous EC, endometrioid EC, and mixed serous and endometrioid EC. LINC00483 was upregulated in mixed serous and endometrioid EC compared with that in the normal tissues according to UALCAN database. In addition, candidate small molecular drugs were screened out by ConnectivityMap based on the 77 DEmRNAs in the ceRNA network. Eventually, C2orf48, LINC00483, and AC110491.1 were identified as three key lncRNAs in EC.

Trends in actionable mutations for recurrent ovarian and endometrial cancer at a single institution

High-resolution copy number analysis of clear cell endometrial carcinoma

Homologous recombination deficient endometrial serous carcinoma: implications for PARPi therapy

Background: Endometrioid and serous carcinomas of the uterus, the two most common histological types of endometrial carcinoma, have been shown to have distinct clinicopathological characteristics and to be underpinned by distinct constellations of molecular aberrations. We sought to define the biological processes that govern the clinical behavior of endometrial cancers based on their transcriptomic characteristics as defined by RNA-sequencing. Material and Methods: RNA-sequencing-based gene expression and clinicopathological data from 323 endometrial cancers were retrieved from The Cancer Genome Atlas (TCGA). Sixteen prototype genes representative of different biological processes that would likely play a role in endometrial and other hormone-driven cancers were defined. TCGA RNA-sequencing data were used to determine the transcription module of each prototype gene. The expression of prototype genes and modules and their association with outcome was assessed in univariate and multivariate survival models in the whole cohort, and in specific subtypes, including endometrioid vs serous, grade 1, 2 and 3 cancers, and the genomic subtypes as described in the TCGA study. Results: The clinical behavior of endometrial cancers was found to be associated with hormone receptor signaling, PI3K pathway signaling and DNA mismatch repair processes. Furthermore, when adjusted for the known prognostic clinicopathological parameters, we found that MSH6 mRNA expression was independently associated with the outcome of patients with endometrial cancer. At variance with other hormone-driven tumors, such as breast cancer, the level of expression of proliferation-related genes was not a predictor of outcome in patients with endometrial cancers. The biological processes governing the outcome of endometrioid and serous endometrial cancers were shown to be distinct; whilst in endometrioid carcinomas hormone receptor, PI3K and DNA mismatch repair modules were associated significantly with outcome in univariate analysis, the clinical behavior of serous cancers was significantly associated with the expression of the apoptosis-related gene CASP3 and Wnt signaling (CTNNB1). When stratified according to grade, the PLAU prototype gene and its invasion module were found to be significantly associated with the survival of patients with grade 3 endometrial cancer, but not of those with grade 1 or 2 cancers. Conclusion: Our data suggest that stratification of endometrial cancers according to histological type (i.e. endometrioid vs serous) and potentially grade may be of importance for the design of clinical trials testing targeted therapeutics as these parameters define subgroups of endometrial cancers that not only have distinct genetic aberrations but also distinct molecular pathways that define the outcome of patients with this disease. Citation Format: Britta Weigelt, Christophe Lemetre, Charlotte K.Y. Ng, Salvatore Piscuoglio, Jorge S. Reis-Filho. The clinical behavior of endometrioid and serous endometrial carcinomas is governed by distinct biological processes. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1544. doi:10.1158/1538-7445.AM2014-1544

To understand the role of and differences in molecular alterations between endometrial and ovarian endometrioid adenocarcinomas. We investigated the microsatellite status of 26 ovarian endometrioid adenocarcinomas (OVEMs), 42 endometrial endometrioid adenocarcinomas (EMCAs), and 19 concurrent (endometrial and ovarian) endometrioid adenocarcinomas. We evaluated the expression of the mismatch repair proteins, PTEN and ARID1A, and mutations of PTEN, KRAS, CTNNB1, and PIK3CA. High levels of microsatellite instability (MSI-H) were present in one of 26 OVEMs, 12 of 42 EMCAs, and four of 19 concurrent endometrioid adenocarcinomas. Only four of 19 concurrent endometrioid adenocarcinomas showed identical molecular alterations in their endometrial and ovarian components. Loss of ARID1A or loss of PTEN expression, and MSI-H, were more common in EMCAs than OVEMs (P = 0.044, P = 0.004, and P = 0.012, respectively). MSI-H in endometrial endometrioid adenocarcinomas was also related to loss of ARID1A expression (P < 0.001). In the cohort of MSI-H endometrioid adenocarcinomas involving the endometrium (n = 16), MSH6-deficient cases showed higher frequencies of CTNNB1 and PIK3CA mutations (P = 0.008 and P = 0.036, respectively), but lower frequencies of KRAS mutation (P = 0.011), than PMS2-deficient cases. The different frequencies of molecular genetic alterations between endometrial endometrioid adenocarcinomas and ovarian endometrioid adenocarcinomas imply that distinct processes may be involved in their tumorigenesis or tumour progression.

5574 Background: Treatment options in recurrent endometrial carcinoma (EC) are limited. Endometrioid EC shows alterations in PTEN, a possible biomarker of response to PARP inhibitors (PARPi). Similarly, homologous recombination deficiency (HRd), a biomarker of response to PARPi in ovarian cancer, is associated with serous EC harbouring TP53 mutations. Preclinical EC models have shown synergy between combining a PARPi and immune checkpoint inhibitor (ICI). Methods: A pilot multi-centre, non-randomized, phase II trial enrolled patients (pts) with recurrent serous or endometrioid EC in two consecutive cohorts (NCT03016338). In the first cohort (C1) pts received niraparib 200 or 300 mg qd, based on baseline body weight and platelet count, in 4 week (w) cycles. In the second cohort (C2) niraparib was given with dostarlimab 500 mg q 3 w for 4 cycles, followed by 1000 mg q 6 w thereafter. There was no limit on prior lines of therapy. Prior ICI was not allowed in C2. Primary endpoint was clinical benefit rate (CBR; complete, partial response or stable disease ≥16w). Secondary endpoints included toxicity assessment and ORR. CT scans were performed q 8 w. Potential biomarkers were assessed in archival tissue by IHC (PTEN, p53, MMR, PDL-1 [threshold 1%]) and a NGS panel (including TP53, PTEN, POLE and other HRd genes). Tumour mutational burden-high (TMBh) was defined as top 20% mutation load. Results: In C1, 25 pts were enrolled (23 evaluable for response). Median age was 69 years old, 64% had serous EC, 72% were platinum resistant (PlatR) and median prior therapies was 2 (range 1-4). Median number of cycles was 3. The CBR was 20% (95% CI: 9-39) and median clinical benefit (CB) duration was 5.3 (1.8-7.2) months. The ORR was 1/23 (4%; 0-20). Related grade (g) ≥3 AEs ≥10% were anemia (24%), fatigue (16%) and thrombocytopenia (16%). In C2, 22 pts were enrolled (all evaluable) and two continue on-treatment. Median age was 64 years old, 46% had serous EC, 68% were PlatR and median prior therapies was 2 (1-6). Three pts had MMR deficient (MMRd) tumors (14%) and one pt a POLE mutation (5%). Median number of cycles was 3. The CBR was 31.8% (16-53) and median CB duration was 6.8 months (3.7-9.5). The ORR was 3/22 (14%; 3-35), out of the three responders one had MMRd and one a POLE mutation. Related g≥3 AEs ≥10% were anemia (27%) and neutropenia (14%). No significant correlation was detected between CB and IHC markers (PTEN, p53, MMR, PDL-1), or NGS ( PTEN, TP53, HRd TMBh) in C1 and C2. Conclusions: Niraparib as single agent for treatment in a PlatR enriched recurrent EC population showed modest activity with clinical benefit rate at 16w of 20%. The combination of niraparib and dostarlimab showed a clinical benefit rate at 16w of 31.8% in a predominantly PlatR recurrent EC. PTEN loss by IHC or NGS, and alterations in HRd genes did not correlate with clinical benefit. Clinical trial information: NCT03016338.

Endometrial serous carcinoma (ESC) and FIGO (International Federation of Gynecology and Obstetrics) grade 3 endometrioid adenocarcinoma (EC) are high-grade endometrial tumors that have different clinical and morphologic attributes. Alteration of p53 tumor suppressor protein function has been implicated in the pathogenesis of both tumors, although the mechanisms may differ. We sought to investigate this difference by comparing immunohistochemical expression of p53 and mdm2. p53 immunoreactivity often correlates with gene mutation, whereas increased mdm2 expression is linked to complex formation with wild-type p53 resulting in its inactivation. Twenty cases of ESC and 21 cases of EC were evaluated and an immunoreactivity score (IRS) was assigned using both the percentage of cells stained and the intensity of staining. The overall IRSs were significantly different in ESCs versus ECs for both p53 and mdm2 (p < 0.001 and p < 0.01, respectively). Strong mean immunoreactivity for p53 was detected in 15 (75%) ESCs as compared to only weak mean immunoreactivity in 17 (81%) ECs. Conversely, for mdm2 expression, 17 (81%) ECs had moderate mean immunoreactivity whereas 9 (45%) ESCs showed only weak mean immunoreactivity. mdm2 expression more closely correlated with p53 expression in ECs than in ESCs. In ECs, mdm2 was detected in 16 of 17 (94%) p53-positive tumors but in only 1 of 3 (33%) p53-negative tumors (p < 0.025). In ESCs, mdm2 was detected in 9 of 15 (60%) p53-positive tumors but in none of the 5 p53-negative tumors (p < 0.10). Overall, our results demonstrate an inverse relationship between the expression of p53 and mdm2 in ESC versus high-grade EC. Specifically, strong p53 immunoreactivity is associated with weak mdm2 expression-in ESC and weak p53 expression is associated with moderate mdm2 expression in EC. These results suggest different pathogenetic pathways resulting in loss of normal p53 function in these two tumors: by p53 gene mutation (strong p53 overexpression) in ESCs, or by mdm2 complex formation and inactivation of p53 in high-grade ECs.

TP53 status is the most important prognostic biomarker in endometrial carcinoma. We asked the question whether p53 mutated endometrial endometrioid carcinomas grade 3 (EEC3) or endometrial serous carcinomas (ESC), the latter ubiquitously harboring TP53 mutation, have different outcomes. TP53 mutation status was assessed by surrogate p53 immunohistochemistry on 326 EEC3 and ESC from 2 major cancer centers in Canada. Mutant-type p53 expression, including overexpression, complete absence, or cytoplasmic expression, was distinguished from the wild-type pattern. Statistical associations with clinico-pathological parameter, other key biomarkers, and survival analyses were performed. P53 mutant-type immunohistochemistry was observed in all 126 ESC and in 47/200 (23.5%) EEC3. ESC and p53 mutated EEC3 had an unfavorable outcome compared with p53 wild-type EEC3 (hazard ratio=2.37, 95% confidence interval=1.48-3.80, P=0.003, hazard ratio=2.19, 95% confidence interval=1.16-4.12, P=0.016, respectively) in multivariable analyses adjusted for age, stage, center, and presence of lymph-vascular invasion. There was no significant difference in survival between ESC and p53 mutated EEC3 in multivariable analysis. Furthermore, p53 mutated EEC3 and ESC almost completely overlapped in univariate survival analysis when mismatch repair (MMR)-deficient cases were excluded, which suggests that EEC3 harboring combined MMR deficiency and TP53 mutations behave more according to the MMR status. Significant differences between p53 mutated MMR-proficient EEC3 and ESC in PTEN and p16 expression status remained. p53 mutated, MMR-proficient EEC3 and ESC have overlapping survival significantly different from p53 wild-type EEC3, which justifies a similar treatment with current non-targeted standard therapy. Although this is so, separate classification should continue due to biological differences that will become important for future targeted therapy.

Preferentially expressed antigen in melanoma (PRAME) is a cancer testes antigen initially employed as a diagnostic marker for melanoma. Although negative in most normal tissues, its expression has been reported in benign endometrial glands. Additionally, PRAME expression has been identified in a growing list of solid and hematologic malignancies and is of interest as a predictive biomarker, as cancer vaccination strategies and adoptive T-cell transfer targeting this molecule are under clinical investigation; additionally, PRAME may identify candidates for retinoid therapy. However, expression of PRAME has not been well-studied in endometrial cancers. We herein evaluate PRAME expression in endometrial carcinomas to better characterize its limitations as a diagnostic melanoma marker as well as its potential as a predictive biomarker in endometrial carcinomas. PRAME expression was evaluated in 256 endometrioid (n=235) and serous (n=21) endometrial carcinomas via tissue microarray. In all, 89% (227/256) demonstrated some degree of nuclear PRAME expression, including 88% (207/235) of endometrioid carcinomas and 95% (20/21) of serous carcinomas. Diffuse (>50%) expression was observed in 70% (179/256) of all cases, including 69% (163/235) of endometrioid carcinomas and 76% (16/21) of serous carcinomas. There was no association between degree of expression and grade, mismatch repair protein status, or stage. The widespread expression of PRAME in endometrial carcinomas suggests this marker should not be interpreted as specific for melanoma in this context. However PRAME may have utility as a predictive biomarker in endometrial cancer, and expansion of testing of PRAME-based therapies to endometrioid and serous endometrial carcinomas may lead to new therapeutic options for these endometrial cancer subtypes.

Endometrial carcinomas - Challenges and updates on selected topics.

Endometrial serous carcinoma (ESC) represents the most aggressive subtype of endometrial carcinoma (EC). According to The Cancer Genome Atlas (TCGA), ESC exhibits a genomic profile characterised by frequent TP53 mutations and somatic copy-number alterations (SCNA). Several studies have suggested the role of intratumour heterogeneity (ITH) in tumour progression and therapy resistance, highlighting ITH as a challenge for personalised medicine. ITH is described as the co-existence of clonal and subclonal cellular populations within a single tumour. To date, the extent and prevalence of ITH in ESC have not been fully evaluated. The aim of this study was to address ITH analysis in ESC. We performed a descriptive integrated molecular approach using targeted sequencing and multiplex ligation-dependent probe amplification (MLPA) to identify mutations and SCNA patterns, respectively. Eight ESC were examined, selecting three tumour regions per case and their corresponding normal tissue. For targeted sequencing a gene panel of 40 genes based on TCGA and other survey data was performed. For MLPA different probe mixes were used to detect SCNA in 106 genes. Analysis of mutations and SCNA were performed in each sample and comparative analysis of the three tumour regions was also conducted. Targeted sequencing showed that mutations in TP53, PIK3CA and PPP2R1A were ubiquitous in all tumour regions. Moreover, MLPA results demonstrated a high frequency of SCNA, according to the already known presence of genomic instability in ESC. Unlike the homogeneous distribution of somatic mutations, SCNA exhibited ITH affecting targetable genes such as ERBB2. Our study suggests that somatic gene copy-number alterations are the main source of ITH in ESC.