HER2 Testing in Endometrial Serous Carcinoma: Time for Standardized Pathology Practice to Meet the Clinical Demand

Molecular and Clinicopathologic Characterization of HER2-overexpressed Squamous Cell Carcinoma of the Cervix

HER2 amplification in cervical cancer has been associated with worse clinical prognosis and a potential favorable response to HER2 inhibitors. Immunohistochemistry for the HER2 receptor is a universally accepted surrogate test for HER2 amplification, but no standardized scoring system currently exists for cervical carcinomas. In this study, we investigated HER2 overexpression in cervical squamous cell carcinoma and correlated it with HER2 amplification using fluorescence in situ hybridization (FISH) and molecular methods. Seventy-two cases of human papillomavirus-associated cervical cancer were retrospectively reviewed, and at least 2 representative tumor sections were stained for HER2. HER2 scoring was performed using the 2018 American Society of Clinical Oncology/College of American Pathologist breast cancer criteria, and cases with equivocal (2+) to positive (3+) expression were analyzed for HER2 amplification using FISH and next-generation sequencing. The average patient age was 50 yrs (range: 27-85 yr), with most patients being African American (73.6%) and diagnosed at FIGO stage I (65.3%). Nineteen (26.4%) had equivocal HER2 expression and 4 (5.5%) showed positive expression. Three of the 4 cases with positive expression had enough tumors for FISH, and all 3 were amplified. Three cases with equivocal expression showed HER2 polysomy on FISH, and none showed HER2 amplification. Late clinical stage, high tumor grade, and regional lymph node metastasis were significantly correlated with HER2 overexpression and HER2 amplification. Next-generation sequencing of the 3 HER2-amplified tumors showed amplification of various genes, including CD274, JAK2, BIRC3, and ERBB2, and a PIK3CA missense mutation. In summary, HER2 immunohistochemistry is a reliable predictive marker of HER2 amplification in cervical cancer.

Trastuzumab deruxtecan (DS-8201a), a HER2-targeting antibody-drug conjugate, demonstrates in vitro and in vivo antitumor activity against primary and metastatic ovarian tumors overexpressing HER2

High-grade serous ovarian cancer (HGSOC) and ovarian clear cell carcinoma (CC), are biologically aggressive tumors endowed with the ability to rapidly metastasize to the abdominal cavity and distant organs. About 10% of HGSOC and 30% of CC demonstrate HER2 IHC 3 + receptor over-expression. We evaluated the efficacy of trastuzumab deruxtecan (T-DXd; DS-8201a), a novel HER2-targeting antibody-drug conjugate (ADC) to an ADC isotype control (CTL ADC) against multiple HGSOC and CC tumor models. Eleven ovarian cancer cell lines including a matched primary and metastatic cell line established from the same patient, were evaluated for HER2 expression by immunohistochemistry and flow cytometry, and gene amplification by fluorescence in situ hybridization assays. In vitro experiments demonstrated T-DXd to be significantly more effective against HER2 3 + HGSOC and CC cell lines when compared to CTL ADC (p < 0.0001). T-DXd induced efficient bystander killing of HER2 non-expressing tumor cells when admixed with HER2 3 + cells. In vivo activity of T-DXd was studied in HER2 IHC 3 + HGSOC and CC mouse xenograft models. We found T-DXd to be significantly more effective than CTL ADC against HER2 3 + HGSOC (KR(CH)31) and CC (OVA10) xenografts with a significant difference in tumor growth starting at day 8 (p = 0.0003 for KR(CH)31, p < 0.0001 for OVA10). T-DXd also conferred a survival advantage in both xenograft models. T-DXd may represent an effective ADC against primary and metastatic HER2-overexpressing HGSOC and CC.

Criteria for assessing evidence for biomarker-targeted therapies in rare cancers-an extrapolation framework

Background

Advances in targeted therapy development and tumor sequencing technology are reclassifying cancers into smaller biomarker-defined diseases. Randomized controlled trials (RCTs) are often impractical in rare diseases, leading to calls for single-arm studies to be sufficient to inform clinical practice based on a strong biological rationale. However, without RCTs, favorable outcomes are often attributed to therapy but may be due to a more indolent disease course or other biases. When the clinical benefit of targeted therapy in a common cancer is established in RCTs, this benefit may extend to rarer cancers sharing the same biomarker. However, careful consideration of the appropriateness of extending the existing trial evidence beyond specific cancer types is required. A framework for extrapolating evidence for biomarker-targeted therapies to rare cancers is needed to support transparent decision-making.

Objectives

To construct a framework outlining the breadth of criteria essential for extrapolating evidence for a biomarker-targeted therapy generated from RCTs in common cancers to different rare cancers sharing the same biomarker.

Design

A series of questions articulating essential criteria for extrapolation.

Methods

The framework was developed from the core topics for extrapolation identified from a previous scoping review of methodological guidance. Principles for extrapolation outlined in guidance documents from the European Medicines Agency, the US Food and Drug Administration, and Australia's Medical Services Advisory Committee were incorporated.

Results

We propose a framework for assessing key assumptions of similarity of the disease and treatment outcomes between the common and rare cancer for five essential components: prognosis of the biomarker-defined cancer, biomarker test analytical validity, biomarker actionability, treatment efficacy, and safety. Knowledge gaps identified can be used to prioritize future studies.

Conclusion

This framework will allow systematic assessment, standardize regulatory, reimbursement and clinical decision-making, and facilitate transparent discussions between key stakeholders in drug assessment for rare biomarker-defined cancers.

High-Grade Endometrial Cancer: Molecular Subtypes, Current Challenges, and Treatment Options

Although many recent advancements have been made in women's health, perhaps one of the most neglected areas of research is the diagnosis and treatment of high-grade endometrial cancer (EnCa). The molecular classification of EnCa in concert with histology was a major step forward. The integration of profiling for mismatch repair deficiency and Human Epidermal Growth Factor 2 (HER2) overexpression, can further inform treatment options, especially for drug resistant recurrent disease. Recent early phase trials suggest that regardless of subtype, combination therapy with agents that have distinct mechanisms of action is a fruitful approach to the treatment of high-grade EnCa. Unfortunately, although the importance of diagnosis and treatment of high-grade EnCa is well recognized, it is understudied compared to other gynecologic and breast cancers. There remains a tremendous need to couple molecular profiling and biomarker development with promising treatment options to inform new treatment strategies with higher efficacy and safety for all who suffer from high-grade recurrent EnCa.

HER2 evaluation for clinical decision making in human solid tumours: pearls and pitfalls

The significant clinical benefits of human epidermal growth factor receptor 2 (HER2)-targeted therapeutic agents have revolutionized the clinical treatment landscape in a variety of human solid tumours. Accordingly, accurate evaluation of HER2 status in these different tumour types is critical for clinical decision making to select appropriate patients who may benefit from life-saving HER2-targeted therapies. HER2 biomarker scoring criteria is different in different organ systems, and close adherence to the corresponding HER2 biomarker testing guidelines and their updates, if available, is essential for accurate evaluation. In addition, knowing the unusual patterns of HER2 expression is also important to avoid inaccurate evaluation. In this review, we discuss the key considerations when evaluating HER2 status in solid tumours for clinical decision making, including tissue handling and preparation for HER2 biomarker testing, as well as pathologist's readout of HER2 testing results in breast carcinomas, gastroesophageal adenocarcinomas, colorectal adenocarcinomas, gynaecologic carcinomas, and non-small cell lung carcinomas.

Colombian consensus for the molecular diagnosis of endometrial cancer

Objective: The Cancer Genome Atlas research program (TCGA) developed the molecular classification for endometrial cancer with prognostic and therapeutic utility, which was replaced by the ProMisE (Proactive Molecular Risk Classifier for Endometrial Cancer) classification by consensus and international guidelines due to its high cost. This article aims to present national recommendations from an expert consensus that allows unification and implementation of the molecular classification for women with endometrial cancer nationwide, with a rational use of resources and technology. Methods: Consensus of 36 experts in clinical oncology, oncological gynecology, pathology, and genetics, with clinical practice in the national territory. The leader group performed a literature review and structuring of questions rated 1 to 9 points. A modified nominal group technique was used. There was a face-to-face meeting with master presentations, deliberative dialogue, and Google Forms (Google LLC, Mountain View, CA, USA) questionnaire voting with analysis and discussion of responses. The non-consensual responses led to a second round of voting. The final manuscript was finally prepared and revised. Results: Seven recommendations were formulated integrating the panelist responses based on evidence, but adjusted to the Colombian context and reality. Recommendation 1. The molecular classification is recommended in all the endometrial cancers using the immunohistochemistry markers as subrogated results from the molecular profile initially proposed in the TCGA classification. Recommendation 2. The sequential test strategy is recommended, starting with the immunohistochemistry markers (p53, MLH1, MSH 2, MSH6, PMS2) simultaneously in all the patients, defining to request POLE (DNA polymerase epsilon) (if available) according to the risk classification based on the surgical piece. Recommendation 3. It is recommended, that the gynecologist oncologist should be the one to request the POLE (if available) according to the final pathology report. This test must be requested for all endometrial cancers stage I-II, except in low risk (stage IA low grade endometrioid histology without linfovascular invasion normal p53) and, stages III-IV without residual disease, without affecting the request of subrogated immunohistochemistry molecular markers upon histology. The consensus proposes that the POLE is requested after the immunohistochemistry and according to the categories in the risk classification established by the 2020 ESGO/ESTRO/ESP guidelines. Recommendation 4. It is recommended to perform immunohistochemistry for hormonal receptors for all women with endometrial cancer and the HER2 in patients with p53abn, simultaneously with the others immunohistochemistry markers. Recommendation 5. It is recommended to perform the immunohistochemistry markers (p53, MLH1, MSH2, MSH6 y PMS2) in an initial endometrial biopsy or curettage when the specimen is adequate and available. In case the initial immunohistochemistry is inconclusive, or there are histological discrepancies between the initial and definitive pathology, it is recommended to repeat the molecular profile in the surgical pathology. The immunohistochemistry markers must be reported in the pathology report according to the CAP (College of American Pathologists) recommendations, independently of the type of sample. Recommendation 6. It is recommended to perform MLH1 promoter methylation testing in patients who exhibit loss of expression of MLH1 in immunohistochemistry whether it is accompanied or not with loss of expression of PMS2. All the patients with deficient MMR (mismatch repair), should be sent for genetic counseling to rule out Lynch syndrome. Recommendation 7. It is recommended to consider the molecular classification in addition to the classical histopathological criteria when making adjuvant judgments, as incorporated by the classification of prognostic groups of the 2020 ESGO/ESTRO/ESP guidelines. Conclusions: It is necessary to implement the molecular classification of endometrial cancer in clinical practice in accordance to the Colombian context, due to its prognostic and probably predictive value. This will enable the characterization of the Colombian population in order to offer individualized guided treatments. This is an academic and nonregulatory document.

Targetable ERBB2/HER2 Mutations in Gynecologic Malignancies: Clinicopathological, Immunohistochemical, and Molecular Correlations

Targeted anti-HER2 therapy has been recently added to the standard treatment recommendations in endometrial serous carcinoma. Current eligibility requires testing for HER2 overexpression and/or gene amplification by immunohistochemistry and by fluorescence in situ hybridization. However, clinical trials have also demonstrated the efficacy of anti-HER2 drugs against activating ERBB2/HER2 mutations in a variety of solid tumor types, and fam-trastuzumab deruxtecan is now approved by the US Food and Drug Administration for HER2-mutant non-small cell lung cancer. This study aimed at evaluating the detailed clinical, histomorphological, immunohistochemical, and molecular characteristics of gynecologic malignancies with ERBB2/HER2 mutations. We identified 16 tumors with 19 ERBB2/HER2 mutations in our departmental archives: 11 endometrial primaries, 2 endocervical adenocarcinomas, 1 ovarian mucinous adenocarcinoma, 1 tubo-ovarian undifferentiated carcinoma, and 1 high-grade endometrioid adenocarcinoma of Mullerian origin. ERBB2/HER2 mutations most often involved the tyrosine kinase domain (52.6%), and the most frequent specific mutation was R678Q (31.6%), involving the juxtamembrane domain. More than half (54.5%) of endometrial carcinomas and half of all tumors were MMR-deficient, resulting from MSH6 loss in all but 2 tumors. None of the tumors (0%) were POLE-mutated, while 18.8% were TP53-mutated. HER2 IHC was negative (score 0 or 1+) in 12 tumors (67%) and equivocal (score 2+) in 4 tumors (33%), whereas none of the tumors were scored as HER2 3+. Score 2+ was associated with R678Q, L755S, I767M mutations, and ERBB2/HER2 rearrangement with a breakpoint in exon 23. Concurrent ERBB2/HER2 amplification was identified in 2 endometrial carcinomas, with HER2/CEP17 ratios of 3.1 and 3.5. We also queried the cBioportal database, which revealed 70 ERBB2/HER2-mutant gynecologic tumors with a total of 77 ERBB2/HER2 mutations, most often involving the active site of the tyrosine kinase domain (n=36; 46.8%), and the most common specific mutation was S310F (n=20; 26%), located in the extracellular domain. Our results provide important details regarding the clinicopathological and molecular associations of potentially actionable ERBB2/HER2 mutations in endometrial carcinoma and other gynecological cancer types and contribute to addressing clinical treatment needs and improving pathology testing recommendations in the future.

Performance of HER2 DAKO HercepTest and Ventana 4B5 immunohistochemical assays on detecting HER2 gene-amplification in uterine serous carcinomas

We compared the performance of two commonly-used HER2 immunohistochemistry (IHC) assays in uterine serous carcinomas (USC), correlating with HER2 gene amplification by fluorescence in-situ hybridization (FISH). Sixty-five USCs were stained by both HercepTest™ and PATHWAY 4B5 assays. FISH was performed by HER2 IQFISH pharmDx. Consensus HER2 IHC scoring was performed, and HER2 testing results were evaluated using USC-specific criteria. Complete concordance between HercepTest and 4B5 assays was achieved in 44/65 tumors (68%). The overall HER2 IHC/FISH concordance was 94% (45/48) by HercepTest and 91% (42/46) by 4B5. All HER2 IHC 3+ cases with HercepTest (n = 6) and 4B5 (n = 4) were gene-amplified, corresponding to specificities of 100%. For cases with IHC 2+, 41% (7/17) by HercepTest and 42% (8/19) by 4B5 had HER2 gene amplification. The sensitivity for HercepTest and 4B5 were 38% and 25%, respectively, at a cut-off of IHC 3+ (P = 0.50), and were 81% and 75%, respectively, at a cut-off of IHC 2+ (P > 0.99). Among HER2 IHC 0-1+ cases, 3/42 cases by HercepTest and 4/42 cases by 4B5 showed amplified FISH results, corresponding to overall false negative rates of 19% for HercepTest and 25% for 4B5. By using USC-specific IHC scoring criteria, both HercepTest and 4B5 assays showed high specificities (100%) for HER2 gene amplification in IHC 3+ cases, high IHC/FISH concordance, and comparable sensitivity for detecting HER2 gene amplification. The notable false negative rates using IHC 2+ as a cut-off for reflexing FISH analysis may warrant consideration for performing FISH in IHC 1+ cases until more data become available.

Implementation of HER2 Testing in Endometrial Cancer, a Summary of Real-World Initial Experience in a Large Tertiary Cancer Center

HER2-targeted therapies have transformed the management of advanced or recurrent serous endometrial cancer (EC), leading to an increased clinical demand for HER2 testing. Despite its adoption in select academic centers, the global extent of such tumor testing is unclear. In this study, we report on the initial two-year experience of HER2 testing at a major academic center with a reference gynecologic oncology service and biomarker reference laboratory. All patients who underwent HER2 testing based on physician discretion, reflex HER2 testing, and reference laboratory requests were included. From February 2021 to October 2023, HER2 testing was performed on 192 tumor tissue samples from 180 EC patients. Serous carcinoma constituted 52% of samples, reflecting diagnostic challenges and limited therapeutic options for advanced EC. HER2 positivity was found in 28% of all cases and 30% of p53-aberrant cases. An immunohistochemistry (IHC) score of 3+ was found in 15% of samples, while IHC 2+ was found in 45% (13% IHC 2+/ISH+ and 32% IHC 2+/ISH-). The newly identified 'HER2-low' category comprised 46% of the samples. Heterogeneity was noted in 42% of HER2-positive cases, with complex patterns in 3%. NGS and HER2 IHC-FISH showed a 24% discordance, attributed to intratumoral heterogeneity, tumor cellularity, a small number of amplified cells, and the HER2/CEP17 ratio near the cut-off. This study offers real-world insights into HER2 testing in EC, highlighting the challenges and underscoring the need for standardized guidelines in specimen handling, proficiency testing, and scoring criteria to enhance patient management and therapeutic decision-making.

Construction of a prognostic model for autophagy in Wilm's tumor

BACKGROUND

Wilm's tumor (WT) is one of the most common childhood urological tumors, ranking second in the incidence of pediatric abdominal tumors. The development of WT is associated with various factors, and the correlation with autophagy is currently unclear.

PURPOSE

To develop a new prognostic model of autophagy-related genes (ATG) for WT.

METHODS

Using the Therapeutically applicable research to generate effective treatments (TARGET) database to screen for differentially expressed ATGs in WT and normal tissues. ATGs were screened for prognostic relevance to WT using one-way and multifactorial Cox regression analyses and prognostic models were constructed. The risk score was calculated according to the model, and the predictive ability of the constructed model was analyzed using the ROC (receiver operating characteristic) curve to verify the significance of the model for the prognosis of WT.

RESULTS

Sixty-eight differentially expressed ATGs were identified by univariate Cox regression analysis, and two critical prognostic ATGs (CXCR4 and ERBB2) were identified by multivariate Cox regression analysis. Patients were divided into high-risk and low-risk groups according to the differential expression of these two ATGs. Kaplan-Meier (KM) curves showed a significant difference in survival time between the two groups. The critical prognostic ATGs were combined with race, age, and stage in a multifactorial regression analysis, and the final prognostic model was produced as a line graph.

CONCLUSION

The prognostic model of autophagy-related genes composed of the CXCR4 gene and ERBB2 gene has a specific predictive value for the prognosis of WT, and the present study provides a clear basis for future research on biomarkers and therapeutic targets.

Human Epidermal Growth Factor Receptor 2 Overexpression/Amplification in Primary Ovarian Endometrioid Carcinoma

Human epidermal growth factor receptor 2 (HER2) expression has become increasingly helpful in predicting responses to anti-HER2 agents in gynecological cancers. This study retrospectively analyzed HER2 expression in 48 primary ovarian endometrioid carcinomas. HER2 immunohistochemistry was performed using the Ventana platform (Clone 4B5 monoclonal predilute) following the manufacturer's protocol. HER2 expression was equivocal (score 2+) by image analysis in 2 cases (4.17%) based on the breast cancer criteria. Fluorescence in situ hybridization was negative for HER2 amplification in one case (International Federation of Gynecology and Obstetrics, grade 1) and positive in the other (International Federation of Gynecology and Obstetrics, grade 3). Our findings contribute to the growing evidence that HER2 is overexpressed in a small proportion of ovarian endometrioid carcinoma, and thus may serve as a potential therapeutic target in selected cases.

HER2/ ERBB2 Immunohistochemical Expression and Copy Number Status in Ovarian Mucinous Tumors

Primary mucinous ovarian carcinoma (MOC) is a rare ovarian epithelial cancer, which is often refractory to chemotherapy. HER2-targeting therapy is being increasingly considered in gynecologic malignancies. Although there have been limited studies examining the HER2 status of such tumors, the criteria for HER2 expression scoring have not been standardized for MOC as it has for other sites. This study aimed to survey immunohistochemical HER2 expression patterns in MOC and its precursor, mucinous borderline tumor in correlation with fluorescence in situ hybridization (FISH). Immunohistochemistry (IHC) for HER2 was performed on 12 cases of MOC and 15 mucinous borderline tumors, including 7 with intraepithelial carcinoma. HER2 expression was quantified using the gastric/gastroesophageal carcinoma protocol. Cases were considered 3+ if the tumor cells displayed strong complete or basolateral/lateral membranous staining in ≥10% of tumor cells. Cases (2+) had weak to moderate staining in ≥10% of tumor cells. Cases (1+) had faint staining in ≥10% of tumor cells. Cases considered 0 had no staining or faint staining in <10% of tumor cells. HER2 expression was also quantified with the endometrial serous carcinoma protocol, which uses a 30% tumor cell positivity cutoff. FISH for HER2 was performed on all 3+ and 2+ and a subset of 1+ cases. Of the MOC cases, 25% were 3+ and 1 mucinous borderline tumor with intraepithelial carcinoma had 3+ staining. All 3+ IHC MOC cases had >30% basolateral membranous staining. HER2 amplification was confirmed by FISH on all 3+ IHC cases and in one 2+ IHC case of MOC. Up to 25% of mucinous ovarian tumors showed HER2 IHC overexpression with an excellent correlation between IHC and FISH using the HER2 scoring protocol for either gastric/gastroesophageal carcinoma or uterine serous carcinoma.

A phase 2 trial of zanidatamab in HER2-overexpressed advanced endometrial carcinoma and carcinosarcoma (ZW25-IST-2)

OBJECTIVE

HER2 overexpression is associated with decreased overall survival in metastatic endometrial cancer. Trastuzumab with chemotherapy has demonstrated efficacy for first-line management of advanced HER2+ endometrial carcinoma, but HER2-directed therapy in the recurrent setting is limited. Zanidatamab (ZW25), a humanized, bispecific antibody that simultaneously binds the 2 distinct HER2 epitopes bound by trastuzumab and pertuzumab, has demonstrated safety and activity in HER2+ tumors. Here, we report the results of a phase 2, open-label study evaluating the efficacy and safety of zanidatamab in patients with HER2+ metastatic endometrial carcinoma/carcinosarcoma who received prior treatment.

METHODS

We enrolled 16 patients with HER2+ endometrial carcinoma/carcinosarcoma after progression on ≤2 lines of therapy on a single-arm phase 2 study of zanidatamab. The primary endpoint was overall response rate (ORR; complete or partial response) by Response Evaluation Criteria in Solid Tumors version 1.1. HER2 immunohistochemistry and fluorescence in situ hybridization (FISH) were performed on pretreatment samples. Intratumor HER2 genetic heterogeneity was assessed.

RESULTS

This study did not meet its primary efficacy endpoint. Although a clinical benefit rate of 37.5% was observed by 24 weeks, only 1 patient achieved a partial response (ORR, 6.2%). Eight patients had HER2 intratumor heterogeneity or lacked HER2 amplification by FISH. Decreased HER2 expression on repeat pretreatment samples was observed in 3 (75%) of 4 patients evaluated.

CONCLUSIONS

We observed a low response rate to zanidatamab in recurrent HER2+ endometrial carcinoma/carcinosarcoma, which may be driven by downregulation of HER2 expression. Repeat HER2 testing should be considered prior to second-line HER2-directed therapy.

CLINICALTRIALS

govidentifier: NCT04513665.

HER2 Status Assessment in Endometrial Serous Carcinoma: Comparative Analysis of Two Proposed Testing and Interpretation Algorithms

HER2 status is now routinely assessed in endometrial serous carcinoma (ESC) due to the reported predictive value of HER2 protein overexpression and/or gene amplification. Herein the authors compare 2 proposed testing and interpretation guidelines for HER2 in ESC. Forty-three consecutive cases of ESC that had been dually tested by both HER2 immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) were interpreted using 2 sets of guidelines. Guideline set 1 (GS1) is the 2018 American Society of Clinical Oncology/College of American Pathologists guidelines for breast cancer. Guideline set 2 (GS2) is a recent proposal that is a slight modification of the enrollment criteria for the clinical trial (NCT01367002) that demonstrated a survival benefit for anti-HER2 therapy in ESC. By IHC, GS1 and GS2, respectively classified 39.5% (17/43) and 28% (12/43) of ESC as HER2-negative, 37.2% (16/43) and 53.4% (23/43) as HER2 equivocal, and 23.2% (10/43) and 18.6% (8/43) as HER2-positive ( P > 0.05 for all). IHC and FISH were highly concordant at the extremes using either set of guidelines, as no cases were found to be IHC3+/FISH-negative or IHC 0-1+/FISH-positive. GS1 and GS2 were comparable regarding the proportion of IHC equivocal cases that were HER2 amplified by FISH (19% vs 23% respectively; [ P = 0.71]). GS1 and GS2 displayed 98% (42/43) concordance regarding the final (IHC and/or FISH-based) classification of tumors as being HER2-positive or negative, and the same 13 cases were ultimately classified as HER2 amplified using either GS1 or GS2. One "discordant" case was classified as HER2-positive using GS2 but HER2-negative using GS1 (HER2 IHC score 2+ using both guidelines, HER2:CEP17 signal ratio of 3, HER2 signal number of 3.4). Six (14%) of the 43 cases (FISH Groups: 2, 3, and 4) would require IHC results to interpret the FISH findings using GS1. Because GS1 requires that the HER2 IHC staining be observed within a homogeneous and contiguous invasive cell population, and this is not a requirement in GS2, GS2 may be better suited for ESC given its frequently heterogeneous staining pattern. Additional studies may be required on the optimal interpretation of problematic dual-probe FISH scenarios in GS2 and the necessity for IHC correlation in such scenarios. Using either set of guidelines, our findings support a reflex testing strategy of restricting FISH testing to cases that are IHC equivocal.

Updates in the Use of Immunohistochemical Stains in Breast and Gynecologic Pathology

CONTEXT.—

The use of immunohistochemical stains in breast and gynecologic pathology has become increasingly complex, with various diagnostic, prognostic, and predictive applications.

OBJECTIVE.—

To provide an update and review of immunohistochemical stains used in the practice of breast and gynecologic pathology. Established and new entities are reviewed, with descriptions of histomorphology and immunohistochemical staining patterns and discussion of interpretive pitfalls.

DATA SOURCES.—

Data were obtained from review of the English-language literature and firsthand experience of the authors in breast and gynecologic pathology.

CONCLUSIONS.—

Many entities in breast and gynecologic pathology benefit from evaluation with various immunohistochemical stains. These studies not only aid in the diagnosis and staging of tumors but also can provide prognostic and predictive information. Updated guidelines for recommended ancillary studies such as mismatch repair, p53, and human epidermal growth factor receptor 2 (HER2) studies in endometrium, as well as estrogen and progesterone receptors and HER2 in breast, are discussed. Finally, the use and interpretation of established and novel immunohistochemical stains are discussed in various breast and gynecologic malignancies.

In Vivo and In Vitro Efficacy of Trastuzumab Deruxtecan in Uterine Serous Carcinoma

Uterine serous carcinoma (USC) is a rare, biologically aggressive variant of endometrial cancer with a high recurrence rate and poor prognosis. HER2 overexpression (3+ positivity) by IHC and/or FISH ERBB2 gene amplification is detected in approximately one-third of patients with USC. Clinical trials incorporating trastuzumab with standard chemotherapy have recently demonstrated improved progression-free and overall survival in advanced-stage or recurrent USC that overexpresses HER2. However, a large number of patients with USC eventually developed resistance to trastuzumab. Trastuzumab deruxtecan (T-DXd) is a novel HER2-directed antibody-drug conjugate with a topoisomerase I inhibitor payload recently approved by the Food and Drug Administration (FDA) for multiple tumor indications. Here, we investigated the in vitro and in vivo efficacy of T-DXd in primary USC cell lines and xenografts with different HER2 expression. T-DXd-induced cell growth suppression in HER2-overexpressing cell lines in vitro, increased early and late apoptosis as assessed by annexin and propidium iodide staining, and, similarly to trastuzumab, T-DXd-induced significant antibody-dependent cellular cytotoxicity in the presence of peripheral blood lymphocytes. While negligible activity was detected against USC cell lines with low HER2 expression, T-DXd demonstrated significant bystander killing against USC tumors with low/negligible HER2 when such cells were admixed with HER2 3+ tumor cells in vitro. T-DXd showed tumor growth suppression in in vivo USC PDX models that overexpress HER2 at 3+ levels, prolonging survival when compared with controls, with minimal toxicity. Future clinical trials are warranted in patients with USC failing trastuzumab treatment.

Response of low HER2-expressing ovarian carcinosarcoma to trastuzumab deruxtecan, a case report

•Treatment options are limited for recurrent ovarian carcinosarcoma (OCS).•A patient with HER2 1 + IHC and negative FISH amplification was treated with trastuzumab deruxtecan.•A durable partial response was achieved, suggesting a possible treatment option for OCS patients with HER2 expression.

HER2 Genetic Intratumor Heterogeneity Is Associated With Resistance to Trastuzumab and Trastuzumab Emtansine Therapy in Recurrent High-Grade Endometrial Cancer

Anti-HER2 targeted therapies have recently demonstrated clinical activity in the treatment of high-grade endometrial carcinomas (ECs), particularly serous carcinomas with HER2 amplification and/or overexpression. Intratumor heterogeneity of HER2 amplification or HER2 genetic intratumor heterogeneity (G-ITH) has been associated with resistance to anti-HER2 therapies in breast and gastroesophageal cancers; however, its clinical relevance in EC is unknown. To characterize HER2 G-ITH in EC, archival specimens from a clinically annotated cohort of 57 ECs treated with trastuzumab or trasutuzmab emtansine in the recurrent (n = 38) or adjuvant (n = 19) setting were subjected to central pathology review, HER2 assessment by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH), and next-generation sequencing. HER2 G-ITH, defined as HER2 amplification in 5% to 50% of tumor cells examined by FISH, was identified in 36% (19/53) of ECs and was associated with lower HER2 copy number and levels of protein expression. HER2 IHC revealed spatially distinct areas of strong expression juxtaposed with areas of low/absent expression in tumors with the "cluster" pattern of G-ITH, whereas the "mosaic" pattern was typically associated with a diffuse admixture of cells with variable levels of HER2 expression. HER2 G-ITH was frequently observed in cases with IHC/FISH or FISH/next-generation sequencing discrepancies and/or with an equivocal/negative FISH result (9/13, 69%). Although the objective response rate to anti-HER2 therapy in recurrent ECs was 52% (13/25) for tumors lacking HER2 G-ITH, none (0%, 0/10) of the patients with HER2 G-ITH achieved a complete or partial response (P = .005). HER2 G-ITH was significantly associated with worse progression-free survival (hazard ratio, 2.88; 95% CI, 1.33-6.27; P = .005) but not overall survival. HER2 IHC score, HER2/CEP17 ratio, HER2 copy number, histologic subtype, and other genetic alterations, including PIK3CA hotspot mutations, were not significantly associated with therapeutic response or survival outcomes. Treatment responses were not restricted to serous carcinomas, supporting consideration of anti-HER2 therapy in patients with HER2-positive high-grade ECs of non-serous histology. Our results demonstrate that HER2 G-ITH is an important determinant of response to trastuzumab and trastuzumab emtansine in EC, providing a rationale for the development of novel therapeutic strategies to target HER2-nonamplified resistant tumor subpopulations, such as HER2 antibody-drug conjugates with bystander effects.

HER2 in uterine serous carcinoma: Current state and clinical perspectives

OBJECTIVES

Uterine cancer has the highest incidence and the second-highest mortality rate among gynecologic malignancies in the United States. Although uterine serous carcinoma (USC) represents less than 10% of endometrial carcinomas, it accounts for a disproportionate 50% of tumor relapses and 40% of endometrial cancer deaths. Over the past decade, clinical trials have focused on finding better treatments for this aggressive subtype of endometrial cancer, especially HER2-targeted therapy.

METHODS

We conducted a literature search in PubMed to expand the understanding of HER2 in USC.

RESULTS

HER2 has been established as an important biomarker with prognostic and therapeutic implications in USC. Intratumoral heterogeneity and lateral/basolateral membranous staining of HER2 as well as high discordance between HER2 immunohistochemistry and in situ hybridization are more common in USC than in breast carcinoma. Therefore, a universal HER2 testing and scoring system more suitable to endometrial cancer is needed and currently under investigation.

CONCLUSIONS

This review discusses the clinical perspective of HER2 overexpression/gene amplification in USC, the distinct HER2 staining pattern and the evaluation of HER2 in USC, the resistance mechanisms of HER2-targeted therapy in HER2-positive cancers, and likely areas of future investigation.

HER-2 overexpression in female genital tract clear cell carcinomas: Evaluation of different scoring guidelines, clinicopathological features and prognostic impact

BACKGROUND

Clear cell carcinoma (CCC) is a rare high-grade adenocarcinoma associated with poor response to platinum-based chemotherapy agents in the female genital tract. Human epidermal growth factor receptor 2 (HER2) overexpression is routinely used as a biomarker for targeted therapy in breast and gastric carcinomas, but its role in CCC remains unclear.

METHODS

In this study, HER2 overexpression was evaluated by immunohistochemistry (IHC) using College of American Pathologists (CAP) HER2 scoring guidelines for breast and endometrial serous carcinoma (ESC) on tissue microarray blocks. In equivocal and positive cases, fluorescence in situ hybridization (FISH) was performed. IHC score 3, and all amplified cases on FISH test were considered positive.

RESULTS

Thirty-six cases of ovarian (OCCC), 36 endometrial (ECCC), and 2 cervical CCC were included. According to ESC and breast scoring guidelines, 20 % and 15.1 % of ECCC and 14.7 % and 6 % of OCCC were HER2 positive, respectively. Both cases of cervical CCC were negative. Scoring based on breast carcinoma guideline showed higher concordance (100 %) with gene amplification results, in comparison with ESC guideline (82.7 %). On multivariate survival analysis, HER2 positive ECCC and OCCC (based on ESC scoring methods) had significantly lower overall and disease-free survivals (OS, DFS) (P < 0.05).

CONCLUSION

HER2 immunoscoring based on ESC guideline can yield a higher sensitivity with relevant clinical and prognostic features in OCCC and ECCC. HER2 can be considered a potential biomarker for targeted therapy and future clinical trials.

Current Laboratory Testing Practices for Assessment of ERBB2/HER2 in Endometrial Serous Carcinoma and Colorectal Carcinoma

CONTEXT.—

Therapy targeted at human epidermal growth factor receptor 2 (HER2; also known as ERBB2) was used initially for breast and gastroesophageal carcinoma and has more recently been adopted for endometrial serous carcinoma (ESC) and colorectal carcinoma (CRC). There is evidence that predictive biomarker testing algorithms for HER2 must be tumor type specific and that an algorithm validated for one tumor type cannot be applied to another.

OBJECTIVE.—

To describe current laboratory practices for HER2 assessment in ESC and CRC.

DESIGN.—

We surveyed laboratories participating in the 2021 College of American Pathologists (CAP) HER2 immunohistochemistry proficiency testing program.

RESULTS.—

The survey was distributed to 1548 laboratories and returned by 1195, of which 83.5% (998) were in the United States. For ESC, 24.0% (287) of laboratories reported performing in-house testing for HER2 by immunohistochemical staining and/or in situ hybridization; of these, 44.3% (127) performed it reflexively on all cases of ESC. The most common criterion for evaluating HER2 was the American Society of Clinical Oncology/CAP 2018 guideline for breast carcinoma (69.0%; 194 of 281), whereas only 16.0% (45) of laboratories used guidelines specific to ESC. For CRC, 20.2% (239 of 1185) of laboratories performed in-house HER2 testing, and 82.0% of these (196) did the test only at the clinician's request. A plurality (49.4%; 115 of 233) used gastroesophageal cancer guidelines when scoring CRC, 30.0% (70) used the CRC scoring system from the HERACLES trial, and 16.3% (38) used the American Society of Clinical Oncology/CAP 2018 guideline for breast carcinoma.

CONCLUSIONS.—

Laboratories vary in their approach to HER2 testing in ESC and CRC. Most laboratories did not report using tumor type-specific recommendations for HER2 interpretation. The lack of standardization could present a challenge to evidence-based practice when considering targeted therapy for these diseases.

New insights for gynecological cancer therapies: from molecular mechanisms and clinical evidence to future directions

Advanced and recurrent gynecological cancers lack effective treatment and have poor prognosis. Besides, there is urgent need for conservative treatment for fertility protection of young patients. Therefore, continued efforts are needed to further define underlying therapeutic targets and explore novel targeted strategies. Considerable advancements have been made with new insights into molecular mechanisms on cancer progression and breakthroughs in novel treatment strategies. Herein, we review the research that holds unique novelty and potential translational power to alter the current landscape of gynecological cancers and improve effective treatments. We outline the advent of promising therapies with their targeted biomolecules, including hormone receptor-targeted agents, inhibitors targeting epigenetic regulators, antiangiogenic agents, inhibitors of abnormal signaling pathways, poly (ADP-ribose) polymerase (PARP) inhibitors, agents targeting immune-suppressive regulators, and repurposed existing drugs. We particularly highlight clinical evidence and trace the ongoing clinical trials to investigate the translational value. Taken together, we conduct a thorough review on emerging agents for gynecological cancer treatment and further discuss their potential challenges and future opportunities.

Development and validation of MRI-based radiomics model to predict recurrence risk in patients with endometrial cancer: a multicenter study

OBJECTIVES

To develop a fusion model based on clinicopathological factors and MRI radiomics features for the prediction of recurrence risk in patients with endometrial cancer (EC).

METHODS

A total of 421 patients with histopathologically proved EC (101 recurrence vs. 320 non-recurrence EC) from four medical centers were included in this retrospective study, and were divided into the training (n = 235), internal validation (n = 102), and external validation (n = 84) cohorts. In total, 1702 radiomics features were respectively extracted from areas with different extensions for each patient. The extreme gradient boosting (XGBoost) classifier was applied to establish the clinicopathological model (CM), radiomics model (RM), and fusion model (FM). The performance of the established models was assessed by the discrimination, calibration, and clinical utility. Kaplan-Meier analysis was conducted to further determine the prognostic value of the models by evaluating the differences in recurrence-free survival (RFS) between the high- and low-risk patients of recurrence.

RESULTS

The FMs showed better performance compared with the models based on clinicopathological or radiomics features alone but with a reduced tendency when the peritumoral area (PA) was extended. The FM based on intratumoral area (IA) [FM (IA)] had the optimal performance in predicting the recurrence risk in terms of the ROC, calibration curve, and decision curve analysis. Kaplan-Meier survival curves showed that high-risk patients of recurrence defined by FM (IA) had a worse RFS than low-risk ones of recurrence.

CONCLUSIONS

The FM integrating intratumoral radiomics features and clinicopathological factors could be a valuable predictor for the recurrence risk of EC patients.

CLINICAL RELEVANCE STATEMENT

An accurate prediction based on our developed FM (IA) for the recurrence risk of EC could facilitate making an individualized therapeutic decision and help avoid under- or over-treatment, therefore improving the prognosis of patients.

KEY POINTS

• The fusion model combined clinicopathological factors and radiomics features exhibits the highest performance compared with the clinicopathological model and radiomics model. • Although higher values of area under the curve were observed for all fusion models, the performance tended to decrease with the extension of the peritumoral region. • Identifying patients with different risks of recurrence, the developed models can be used to facilitate individualized management.

HER2 IHC Expression and Gene Amplification in p53-aberrant High-grade Endometrial Endometrioid Carcinoma Suggests That This Population May Benefit From HER2 Testing and Targeted Therapy

Among gynecologic cancers, uterine serous carcinoma (USC) has been shown to be human epidermal growth factor receptor 2 (HER2) amplified and trastuzumab has been included in the recent National Comprehensive Cancer Network (NCCN) guidelines for treatment of advanced stage or recurrent USC with HER2 overexpression/amplification. There is limited literature suggesting that a subset of high-grade endometrioid carcinomas with aberrant p53 expression may also be HER2 amplified and these patients could benefit from the addition of targeted therapy. We identified 59 p53-aberrant (mismatch repair proficient) FIGO 3 endometrioid carcinomas of the uterus. HER2 immunohistochemistry was performed in all 59 tumors and HER2 fluorescence in situ hybridization (FISH) was performed in 52 of the 59 cases. Four of the 59 cases were HER2 3+ by immunohistochemistry (6.7%), using the American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) 2007, 2013, and 2018 criteria. HER2 FISH was performed in 3 of the 4 cases and was amplified in all 3. Nine, 8, and 7 tumors showed 2+ HER2 staining when applying 2018, 2013, and 2007 criteria, respectively, FISH was performed in 7 tumors and none were amplified. An additional 4 cases did not perfectly meet the 2018 ASCO/CAP criteria but were assigned a score of 2+, none were amplified by HER2 FISH. The remaining 42 cases showed 1+ or no staining for HER2, FISH was successfully performed in 38 tumors and none showed amplification. Approximately half of the tumors fulfilled criteria for HER2-low or HER2-very low (10 HER2-low and 20 HER2-very low). Our data shows that a subset of p53-aberrant high-grade endometrial endometrioid carcinoma express HER2 and these patients may benefit from the addition of targeted therapy. The role of targeted therapy in HER2-low gynecologic carcinoma is currently unexplored.

Discordances in expression of human epidermal growth factor receptor 2 between primary and metastatic uterine carcinosarcoma: A proposal for HER2-targeted therapy specimen selection

Uterine carcinosarcoma (UCS) frequently expresses human epidermal growth factor receptor 2 (HER2) and metastasizes. However, little is known about changes in the HER2 expression status in metastatic lesions and its impact on clinical outcomes. In 41 patients with synchronous or metachronous metastases and matched primary UCSs, we assessed the HER-2 expression using immunohistochemistry and scored it per the 2016 American Society of Clinical Oncology/College of American Pathologists guidelines, modified for UCS. We compared HER2 scores between paired primary and metastatic lesions and reviewed the association between clinicopathological characteristics and impact on overall survival. HER2 scores of 3+, 2+, 1+, and 0 were observed in 12.2 %, 34.2 %, 26.8 %, and 26.8 % of primary tumors, respectively, and 9.8 %, 19.5 %, 43.9 %, and 26.8 % of metastatic tumors, respectively. HER2 intratumoral heterogeneity occurred in 46.3 % and 19.5 % of the primary and metastatic lesions, respectively. The agreement rate of the HER2 score was 34.2 % in the four-tiered scale, while it was 70.7 % in the two-tiered scale (score 0 vs. score ≥ 1+) with fair agreement (к = 0.26). Patients with HER2 discordance showed significantly shorter overall survival (hazard ratios = 2.38, 95 % confidence interval 1.01-5.5, p = 0.049). HER2 discordance was not associated with specific clinicopathological characteristics. Discordance in HER2 status between primary and metastatic tumors in UCS was frequently observed regardless of clinicopathological characteristics and was a poor prognostic factor. Even if one tumor (primary or metastatic) is HER2 negative, HER2 testing of other tumors may be beneficial in terms of patient treatment options.

Trastuzumab deruxtecan (DS-8201a), a HER2-targeting antibody-drug conjugate with topoisomerase I inhibitor payload, shows antitumor activity in uterine and ovarian carcinosarcoma with HER2/neu expression

OBJECTIVES

Carcinosarcomas are highly aggressive gynecologic malignancies containing both carcinomatous and sarcomatous elements with heterogeneous HER2/neu expression and limited therapeutic options. We compared the efficacy of trastuzumab deruxtecan (DS-8201a), a novel HER2/neu-targeting antibody-drug conjugate (ADC) to an ADC isotype control (MAAA-9199) against primary uterine and ovarian carcinosarcomas in vitro and in vivo.

METHODS

Twelve primary carcinosarcoma (CS) cell lines were evaluated for HER2/neu surface expression by immunohistochemistry (IHC) and by flow cytometry, and gene amplification by fluorescence in situ hybridization (FISH) assays. The in vitro experiments included cytotoxicity and bystander killing effect assays on three cell lines of variable HER2/neu expression. In vivo activity was studied in a mouse CS xenograft model of 3+ HER2/neu uterine CS.

RESULTS

In vitro studies showed that DS-8201a was highly effective against uterine and ovarian CS cell lines demonstrating 3+ HER2/neu expression compared to MAAA-9199 control; there was no significant improvement in the 0 HER2/neu CS cell line. However, DS-8201a induced efficient bystander killing of 0 HER2/neu tumor cells when admixed with 3+ HER2/neu cells. In vivo studies confirmed that DS-8201a was more effective than MAAA-9199 in 3+ HER2/neu-expressing CS xenografts.

CONCLUSION

DS-8201a may represent a novel and highly effective ADC against HER2/neu-expressing CS.

Potential biomarkers in endometrial cancer: a narrative review

CONTEXT

Every year, approximately 0.4 million women suffer from endometrial cancer (EC) worldwide and it has become the most common gynecological malignancy. Almost 66% of EC cases are diagnosed at an early stage and can be cured by performing surgery while those at an advanced stage turns out to be fatal. Biomarkers of endometrial cancer would be very valuable for screening of women who are at high risk and in detecting the chance of recurrence of disease.

OBJECTIVE

The current article has reviewed studies published on expression of biomarkers and susceptibility to EC.

METHODS

Google Scholar and PubMed were used as searching platforms and we have majorly considered the literature from last 10 years.

RESULTS

Potential biomarkers of EC identified from various studies were summarised.

HER2 Amplification in p53-Mutated Endometrial Carcinomas

p53-mutated endometrial carcinomas tend to recur and develop distant metastases. Therefore, the detection of new potential therapeutic targets such as HER2 is particularly interesting. In this retrospective study, which considered over 118 endometrial carcinomas, the p53 mutation was detected in 29.6% of cases. In these cases, the HER2 protein profile was studied via immunohistochemistry, and an overexpression of HER2 protein (++ or +++) was noted in 31.4%. The CISH technique was used in these cases to determine if gene amplification was present. In 18% of cases, the technique was not conclusive. Amplification of the HER2 gene was observed in 36.3% of cases and 36.3% of cases showed a polysomal-like aneusomy for centromere 17. Amplification was found in serous carcinomas, clear cell carcinomas and carcinosarcomas, highlighting the future potentiality of HER2-targeted therapies in these variants of aggressive carcinomas.

The Polish Society of Gynecological Oncology Guidelines for the Diagnosis and Treatment of Endometrial Carcinoma (2023)

BACKGROUND

Due to the increasing amount of published data suggesting that endometrial carcinoma is a heterogenic entity with possible different treatment sequences and post-treatment follow-up, the Polish Society of Gynecological Oncology (PSGO) has developed new guidelines.

AIM

to summarize the current evidence for diagnosis, treatment, and follow-up of endometrial carcinoma and to provide evidence-based recommendations for clinical practice.

METHODS

The guidelines have been developed according to standards set by the guideline evaluation tool AGREE II (Appraisal of Guidelines for Research and Evaluation). The strength of scientific evidence has been defined in agreement with The Agency for Health Technology Assessment and Tariff System (AOTMiT) guidelines for scientific evidence classification. The grades of recommendation have been based on the strength of evidence and the level of consensus of the PSGO development group.

CONCLUSION

Based on current evidence, both the implementation of the molecular classification of endometrial cancer patients at the beginning of the treatment sequence and the extension of the final postoperative pathological report of additional biomarkers are needed to optimize and improve treatment results as well as to pave the route for future clinical trials on targeted therapies.

Alarming trends and disparities in high-risk endometrial cancer

PURPOSE OF REVIEW

To summarize the most recent publications highlighting the trends and disparities among patients diagnosed with high-risk endometrial cancer.

RECENT FINDINGS

Endometrial cancer mortality continues to rise, driven by the increasing incidence of high-risk histologic subtypes that accounts for a disproportionate number of endometrial cancer deaths. The lack of progress made in endometrial cancer treatment, particularly of high-risk histologic subtypes, disproportionately affects black women who are more likely to be diagnosed with these aggressive tumor types. Even when accounting for high-risk histology, various factors across the spectrum of care may influence the survival disparities between black and white women, including timely access to guideline-concordant care, clinical trial enrollment, and systemic racism that impacts cancer outcomes.

SUMMARY

In this review, we highlight the disproportionate impact of worsening endometrial cancer mortality and healthcare inequalities contributing to the endometrial cancer survival disparity between black and white women.

The evolving therapeutic landscape of trastuzumab-drug conjugates: Future perspectives beyond HER2-positive breast cancer

A novel class of drugs, antibody-drug conjugates (ADCs), are now rapidly emerging as highly effective treatments for solid tumours. ADCs conjugate conventional chemotherapeutics with highly selective targeted monoclonal antibodies. Anti-HER2 therapies selectively target cancer cells expressing human epidermal growth factor receptor 2 (HER2), among them trastuzumab has been the first HER2-targeting monoclonal antibody to achieve successful results that made it the backbone of anti-HER2 therapies. Trastuzumab drug conjugates (T-DCs), use trastuzumab as a selective antibody to lead cytotoxic drugs inside cancer cells. Trastuzumab-emtansine (T-DM1) and trastuzumab-deruxtecan (T-Dxd) are the two approved T-DCs. T-Dxd along with other five T-DCs represents "second generation ADCs" that has been firstly tested in HER2 positive breast cancer (BC) and then in HER2-low BC and other cancers showing promising results thanks to extraordinary and innovative pharmacokinetic and pharmacodynamic characteristics. The evidence generated so far are establishing them as a completely new class of agents effective in solid cancer treatments but also warrants physicians against unconventional toxicity profiles. The role of T-DCs in HER2-positive BC has been largely reviewed, while in this review, we provided for the first time in literature an overview of trastuzumab drug conjugates (T-DCs) approved and/or in clinical development with a specific focus on their efficacy and safety profile in HER2-low BC and other solid tumours different from BC. We started by analysing T-DCs biological characteristics that underly the differences in T-DCs pharmacodynamics and safety profile, then presented the main evidence on the activity and efficacy of these emerging T-DCs in HER2-low BC and other HER2 overexpressing and/or mutated solid tumours and lastly, we provided an overview of the complex and still evolving scenario in which these compounds should be allocated. A specific focus on possible combination strategies with other drugs such as immunotherapy, chemotherapy and target therapy, to increase T-DCs activity and eventually overcome future upcoming resistance mechanisms, are here also critically reviewed.

Pan-Asian adapted ESMO Clinical Practice Guidelines for the diagnosis, treatment and follow-up of patients with endometrial cancer

The most recent version of the European Society for Medical Oncology (ESMO) Clinical Practice Guidelines for the diagnosis, treatment and follow-up of patients with endometrial cancer was published in 2022. It was therefore decided, by both the ESMO and the Indian Society of Medical and Paediatric Oncology (ISMPO), to convene a virtual meeting in July 2022 to adapt the ESMO 2022 guidelines to take into account the variations in the management of endometrial cancer in Asia. These guidelines represent the consensus opinion of a panel of Asian experts representing the oncological societies of China (CSCO), India (ISMPO), Indonesia (ISHMO), Japan (JSMO), Korea (KSMO), Malaysia (MOS), the Philippines (PSMO), Singapore (SSO), Taiwan (TOS) and Thailand (TSCO). Voting was based on scientific evidence and was conducted independently of the current treatment practices and treatment access constraints in the different Asian countries, which were discussed when appropriate. The aim of this guideline manuscript is to provide guidance for the optimisation and harmonisation of the management of patients with endometrial cancer across the different regions of Asia, drawing on the evidence provided by Western and Asian trials whilst respecting the variations in clinical presentation, diagnostic practices including molecular profiling and disparities in access to therapeutic options, including drug approvals and reimbursement strategies.

The role of HER2 as a therapeutic biomarker in gynaecological malignancy: potential for use beyond uterine serous carcinoma

Human epidermal growth factor receptor 2 (HER2) is a prognostic biomarker and therapeutic target in carcinomas of the breast, stomach and colon. In 2018, clinical trial data confirmed the prognostic and predictive role of HER2 in uterine serous carcinoma, with a demonstrated survival benefit from combined chemotherapy and anti-HER2 targeted therapy in patients with advanced or recurrent disease. Approximately one-third of uterine serous carcinomas demonstrate HER2 protein overexpression and/or gene amplification and HER2 immunohistochemistry, supplemented by in situ hybridisation in equivocal cases, is fast becoming a reflex ancillary test at time of diagnosis. The potential role of HER2 in gynaecological tumours other than uterine serous carcinoma is yet to be firmly established. With the advent of personalised medicine, routine tumour sequencing and pursuit of targeted therapies, this is a field currently under active investigation. Emerging data suggest triaging endometrial carcinomas for HER2 analysis based on molecular classification may be superior to histotype-based testing, with copy-number high/p53 mutant tumours enriched for HER2 overexpression or amplification. Accordingly, many carcinosarcomas and a subset of clear cell and high-grade endometrioid carcinomas may be eligible for HER2 targeted therapy, although any clinical benefit in this context is currently undefined. For ovarian carcinomas, combined data support the role of HER2 as a prognostic biomarker, however its use as a therapeutic target is yet to be elucidated through clinical trials. In the cervix, reported rates of HER2 overexpression vary and are generally low, and currently there is insufficient evidence to justify routine HER2 testing in this context. Limited data suggest HER2 holds promise as a prognostic and predictive biomarker in vulvar Paget disease. Future clinical trials, with pathologist input to develop and refine site-specific scoring criteria, are required to establish what role HER2 might play more broadly in gynaecological cancer care.

The statuses of HER2 expression and mismatch repair in endometrial clear cell carcinoma

High-grade endometrial carcinomas (HGEC) are difficult to classify. With the current use of HER2-based therapy in serous carcinoma, a diagnosis of clear cell carcinoma (CCC) has the potential to exclude patients from receiving therapy. Therefore, we examined HER2 expression in our CCC patients. The preparations of 8 patients with CCC who underwent hysterectomy, bilateral salpingo-oophorectomy, and lymph node dissection were re-evaluated. Patients did not have any prior treatment. Histopathologic parameters that were evaluated include cytoplasmic clearing, nuclear atypia, mitotic activity, hobnail architecture, hyalinized cores, hyaline globules, stratification of epithelial lining papillae, or glandular structures, and highly atypical cell layers. Immunohistochemically, HER2, ER, PR, HNF1β, Napsin A, MLH1, MSH2, MSH6 and PMS2 were applied. HER2 staining pattern, ASCO/CAP protocol used for endometrial carcinom was used. HER2 was positive in 3 of our 8 CCC patients (37.5%). While all of our HER2 + cases were Napsin A and HNF1β positive, MMR proteins were intact and ER and PR were negative. Two patients had wild type p53 and 1 patient had aberrant p53 staining. Considering that there is not always a consensus between SC and CCC, even among gynecopathologists, tumor heterogeneity and different tumor components may exist, and while patients may be diagnosed with CCC and benefit from HER2 therapy, there is also a possibility that they may not benefit from the treatment. The fact that 37.5% of our CCC cases were HER2 + is a finding with strong implications for the therapeutic approach. As a result of our study, in patients with CCC, if MMR is intact and ER-PR is negative, regardless of the p53 staining pattern, HER2 testing may be an objective screening method for patients who are likely to benefit from HER-targeted therapy. Consequently, patients with a diagnosis of CCC can be candidates for future clinical trials of HER2-targeted therapy.

Molecular testing for endometrial cancer: An SGO clinical practice statement

The Cancer Genome Atlas publication first described the genomic landscape of endometrial cancer and characterized these cancers into four molecular subtypes with different prognoses. The Proactive Molecular Classifier for Endometrial Cancer was developed to more easily and inexpensively classify endometrial cancers into four similar molecular subtypes which are termed POLE, mismatch repair deficient, p53 abnormal and no specific molecular profile. Beyond these four subtypes, other molecular biomarkers may influence clinical behavior and response to targeted therapies and include beta-catenin, Her2 amplification, PI3K/mTOR/AKT alterations, L1CAM, hormone receptor expression, tumor mutational burden, and ARID1A. There are numerous clinical trials exploring treatment escalation and de-escalation within the four molecular subtypes as well as matching targeted therapies to specific mutational or biomarker profiles. All endometrial cancers should undergo basic molecular classification that includes assessment of mismatch repair status. POLE and p53 status are prognostic and may become actionable in the future. Clinicians who treat patients with endometrial cancer should understand the role of molecular classification in guiding treatment. The goal of this practice statement is to guide appropriate testing, interpretation, and application of molecular information in endometrial cancer.

PRAME Expression in Endometrioid and Serous Endometrial Carcinoma: A Potential Immunotherapeutic Target and Possible Diagnostic Pitfall

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.

Gene-Expression Profiling of Mucinous Ovarian Tumors and Comparison with Upper and Lower Gastrointestinal Tumors Identifies Markers Associated with Adverse Outcomes

PURPOSE

Advanced-stage mucinous ovarian carcinoma (MOC) has poor chemotherapy response and prognosis and lacks biomarkers to aid stage I adjuvant treatment. Differentiating primary MOC from gastrointestinal (GI) metastases to the ovary is also challenging due to phenotypic similarities. Clinicopathologic and gene-expression data were analyzed to identify prognostic and diagnostic features.

EXPERIMENTAL DESIGN

Discovery analyses selected 19 genes with prognostic/diagnostic potential. Validation was performed through the Ovarian Tumor Tissue Analysis consortium and GI cancer biobanks comprising 604 patients with MOC (n = 333), mucinous borderline ovarian tumors (MBOT, n = 151), and upper GI (n = 65) and lower GI tumors (n = 55).

RESULTS

Infiltrative pattern of invasion was associated with decreased overall survival (OS) within 2 years from diagnosis, compared with expansile pattern in stage I MOC [hazard ratio (HR), 2.77; 95% confidence interval (CI), 1.04-7.41, P = 0.042]. Increased expression of THBS2 and TAGLN was associated with shorter OS in MOC patients (HR, 1.25; 95% CI, 1.04-1.51, P = 0.016) and (HR, 1.21; 95% CI, 1.01-1.45, P = 0.043), respectively. ERBB2 (HER2) amplification or high mRNA expression was evident in 64 of 243 (26%) of MOCs, but only 8 of 243 (3%) were also infiltrative (4/39, 10%) or stage III/IV (4/31, 13%).

CONCLUSIONS

An infiltrative growth pattern infers poor prognosis within 2 years from diagnosis and may help select stage I patients for adjuvant therapy. High expression of THBS2 and TAGLN in MOC confers an adverse prognosis and is upregulated in the infiltrative subtype, which warrants further investigation. Anti-HER2 therapy should be investigated in a subset of patients. MOC samples clustered with upper GI, yet markers to differentiate these entities remain elusive, suggesting similar underlying biology and shared treatment strategies.

Data Set for the Reporting of Endometrial Cancer: Recommendations From the International Collaboration on Cancer Reporting (ICCR)

Endometrial cancer is one of the most common cancers among women. The International Collaboration on Cancer Reporting (ICCR) developed a standardized endometrial cancer data set in 2011, which provided detailed recommendations for the reporting of resection specimens of these neoplasms. A new data set has been developed, which incorporates the updated 2020 World Health Organization Classification of Female Genital Tumors, the Cancer Genome Atlas (TCGA) molecular classification of endometrial cancers, and other major advances in endometrial cancer reporting, all of which necessitated a major revision of the data set. This updated data set has been produced by a panel of expert pathologists and an expert clinician and has been subject to international open consultation. The data set includes core elements which are unanimously agreed upon as essential for cancer diagnosis, clinical management, staging, or prognosis and noncore elements which are clinically important, but not essential. Explanatory notes are provided for each element. Adoption of this updated data set will result in improvements in endometrial cancer patient care.

Association of immunohistochemical profiles with histotypes in endometrial carcinomas

OBJECTIVE

Although a large number of endometrial cancer patients are cured with surgery alone, there are significant numbers of patients with more aggressive variants of endometrial carcinoma for whom the prognosis remains poor. We investigated the effects of prevalence, histotypes, and immunohistochemical profiles on prognostic value in a hospital-based population.

MATERIALS AND METHODS

A retrospective study of surgically resected primary endometrial carcinoma was included. Immunohistochemical stains were performed on formalin-fixed paraffin-embedded tissue microarray sections for β-Catenin, estrogen receptor (ER), progesterone receptor (PR), HER-2, MLH1, MSH2, MSH6, PMS2, and p53.

RESULTS

Loss of mismatch repair expression was detected in 25.4% of samples (29/114, mean age 57 years) of the tumors. The following loss of expression was observed in patients: MLH1/PMS2 in 16.6% of patients, MSH6 in 7.0% of patients, MLH1 in 0.9% of patients, and MSH6/PMS2/MLH1 in 0.9% of patients. Immunohistochemistry of p53 was analyzed for 111 patients. A total of 13 patients (11.7%, mean age 64 years) had p53-abnormal expression (absent, cytoplasmic or diffuse strong positive patterns), and more than half (9/13, 69.2%) had endometrioid histotype. Abnormalities in p53 were significantly associated with histotype (p = 0.001), advanced tumor stage (p = 0.038), death of disease (p = 0.002), PR percentage (p = 0.002), and HER-2 expression (p = 0.018). Immunohistochemical nuclear localization of β-Catenin was detected in 7.1% of the cohort. The combination of p53 and nuclear β-Catenin expressions was not significantly predictive of disease-free or overall survival.

CONCLUSION

The results of this study are useful for management of endometrial cancer in patients with DNA mismatch repair, abnormal p53 expression, or nuclear localization of β-Catenin.

Histopathologic features and molecular genetic landscape of HER2-amplified endometrial carcinomas

HER2 is an established therapeutic biomarker in advanced or recurrent endometrial serous carcinoma. Current clinical guidelines recommend HER2 testing exclusively in this endometrial carcinoma (EC) subtype; however, the full spectrum of ECs harboring HER2 amplification remains ill-defined. The present study characterizes the clinicopathologic and molecular features of HER2-amplified ECs across all histologic subtypes. Retrospective analysis of our institutional cohort of 2,042 ECs subjected to targeted clinical massively parallel sequencing identified 77 (3.8%) cases with HER2 amplification, a group comprised of serous (n = 29), endometrioid (low-grade, n = 2, high-grade, n = 1) and clear cell (n = 4) carcinomas, carcinosarcomas (n = 18) and high-grade ECs with ambiguous features (HGEC, n = 23). A co-existing TP53 mutation was identified in 94% (72/77) of HER2-amplified ECs. Other recurrent genetic alterations included amplification of CCNE1 (22%) and ERBB3 (10%), FBXW7 mutations or deletions (13%), and mutations in PIK3CA (40%) and PPP2R1A (13%). The HER2 immunohistochemistry score was 2+ or 3+ for all evaluable cases (n = 61). Apart from carcinosarcomas, which often showed lower HER2 expression, particularly in the sarcomatous component, HER2 immunohistochemical staining pattern and intensity were similar across EC subtypes. Intratumor heterogeneity in HER2 expression was common and correlated with genetic heterogeneity as detected by fluorescence in-situ hybridization. These results demonstrate the frequent co-occurrence of HER2 amplification with TP53 mutation and high-grade histology, rather than being specific to serous carcinoma, per se. Overall, these findings suggest that HER2 targeted therapy may be more broadly applicable to all high-grade EC histotypes and consideration should be given to expanding therapeutic eligibility.

Endometrial Cancer: An Update on Prognostic Pathologic Features and Clinically Relevant Biomarkers

The prognosis of endometrial cancers has historically been determined by the evaluation of histologic typing, grading, and staging. Recently, molecular classification, pioneered by the 4 prognostic categories from The Cancer Genome Atlas Research Network, has been shown to independently predict the outcome, correlate with biomarker expression, and predict response to adjuvant chemotherapy. In modern-day pathology practice, it has become necessary to integrate the time-honored prognostic pathologic features with molecular classification to optimize patient management. In this review, the significance of the molecular classification of endometrioid carcinomas, the application of practical diagnostic surrogate algorithms, and interpretation of test results will be addressed. Histologic features and theragnostic biomarkers will also be discussed in relation to the molecular subtypes of endometrial cancers.

The Prognostic Effect of HER2 Gene Amplification in High-Grade Endometrial Carcinomas and its Correlation with Protein Overexpression

Introduction. New therapeutic agents and biomarkers are needed for the treatment of aggressive endometrial cancer subtypes. Recently, HER2 has been recommended to be tested routinely in serous endometrial cancers. The aim of this study is to investigate the correlation between HER2 (ERBB2) protein overexpression and HER2 gene amplification and the relationship of HER2 gene amplification with prognosis in cancers with serous morphology. In addition, the concordance of HER2 testing in paired curettage and hysterectomy specimens is also investigated. Methods. Twenty five serous carcinomas and 8 carcinosarcomas with a serous morphology were included in the study. HER2 staining was performed on whole tissue sections by immunohistochemistry (IHC) and fluorescent in situ hybridization (FISH). The system, which was proposed by Fader et al was used to evaluate the stainings. Results. Protein overexpression was detected in 27.3% (n = 9) of the cases, and gene amplification in 30.3% (n = 10). A significant positive correlation was found between the two methods (P < .0001). HER2 IHC revealed a heterogeneous staining pattern, such as intense complete membranous in solid areas, and basolateral in papillary and glandular areas. HER2 gene amplification was significantly associated with shorter overall (P = .005) and disease-free (P = .014) survival. The concordence of the results in curettage and hysterectomy specimens was also significantly high. Conclusion. HER2 is an important prognostic and predictive marker for endometrial cancers with serous morphology. HER2 IHC/ISH testing can be performed by using diagnostic curettage specimens which contain enough viable tumor cells. However, pathologists should be aware of the intratumoral heterogeneity for HER2 staining.

Current Prognostic and Predictive Biomarkers for Endometrial Cancer in Clinical Practice: Recommendations/Proposal from the Italian Study Group

Endometrial carcinoma (EC) is the most common gynecological malignant disease in high-income countries, such as European countries and the USA. The 2020 edition of the World Health Organization (WHO) Classification of Tumors of the Female Genital Tract underlines the important clinical implications of the proposed new histomolecular classification system for ECs. In view of the substantial genetic and morphological heterogeneity in ECs, both classical pthological parameters and molecular classifiers have to be integrated in the pathology report. This review will focus on the most commonly adopted immunohistochemical and molecular biomarkers in daily clinical characterization of EC, referring to the most recent published recommendations, guidelines, and expert opinions.

HER2 Overexpression and Amplification in Uterine Carcinosarcomas With Serous Morphology

Uterine carcinosarcoma (UCS) is an aggressive malignancy with few treatment options. A recent clinical trial has shown an increase in progression-free survival in patients with human epidermal growth factor receptor 2 (HER2)-positive serous endometrial carcinomas treated with anti-HER2-targeted therapies. Few studies have evaluated HER2 expression/amplification in UCS. Similar to serous endometrial carcinoma, the majority of UCS have TP53 mutations and a serous epithelial component, suggesting that UCS may show similar rates of HER2 positivity and therapeutic response. Therefore, we evaluated HER2 expression/amplification in a cohort of UCS over a 5-year period. HER2 immunohistochemistry (IHC) and chromogenic in situ hybridization were performed on tissue microarray and whole tissue sections and scored according to the most recent clinical trial recommendations. Three of 48 UCS (6%) had strong (3+) HER2 IHC expression, and 3 cases (6%) were equivocal (2+). Seven cases (15%) had HER2 amplification by chromogenic in situ hybridization, including all 3 with overexpression and 2 that were equivocal by IHC. Mismatch repair (MMR) protein, p53, and programmed cell death-ligand 1 (PD-L1) expression status was obtained from prior whole section analyses. All HER2-positive cases had a serous morphology and aberrant p53 expression. Only minimal PD-L1 expression was seen in the HER2-positive cases, and none had MMR loss. A subset of UCS with serous morphology have overexpression and/or amplification of HER2, which may predict response to HER2-targeted therapies. HER2-positive UCS may be less susceptible to immune checkpoint inhibition as they uncommonly show MMR deficiency and/or strong PD-L1 expression. Thus, HER2-targeted therapies could be of clinical utility in a subset of UCS without other adjuvant treatment options.

Preferential human epidermal growth factor receptor 2 expression in myometrial and lymphovascular invasion of a uterine carcinosarcoma: A case report

This case report describes a unique pattern of human epidermal growth factor receptor 2 expression in a patient with uterine carcinosarcoma. The endometrial tumor showed biphasic morphology composed of serous carcinoma and a heterologous high-grade sarcoma component. Human epidermal growth factor receptor 2 immunostaining showed positive (3+) expression in foci of myoinvasion, lymphovascular invasion, and lymph node metastasis but was negative in both the endometrial surface tumor and sarcomatous component. Fluorescent in situ hybridization testing for human epidermal growth factor receptor 2 confirmed no amplification within the endometrial surface carcinoma component and amplification of the lymphovascular invasion component. As the use of human epidermal growth factor receptor 2 immunohistochemical evaluation becomes more commonplace for therapeutic consideration in patients with uterine carcinosarcoma, interpretation of the immunohistochemical should be performed preferentially on large tissue sections including both a surface, myoinvasive portions, and suspected areas of lymphovascular invasion and lymph node metastasis.

α-Fetoprotein-Producing Endometrial Carcinoma Is Associated With Fetal Gut-Like and/or Hepatoid Morphology, Lymphovascular Infiltration, TP53 Abnormalities, and Poor Prognosis: Five Cases and Literature Review

The clinicopathological, immunohistochemical, and molecular characteristics of α-fetoprotein (AFP)-producing endometrial carcinoma (AFP+ EC) are poorly understood. From 284 cases of endometrial carcinoma in our pathology archive, we identified five cases (1.8%) of AFP+ EC with fetal gut–like (4/5) and/or hepatoid (2/5) morphology. All cases exhibited lymphovascular infiltration. In addition, 24 cases of endometrial carcinoma with elevated serum AFP levels were retrieved from the literature. The patient age ranged from 44 to 86 years (median: 63). Of 26 cases whose FIGO (International Federation of Gynecology and Obstetrics) stage and follow-up information was available (mean follow-up 24 months), 15 were stage I or II and 11 were stage III or IV. Even in stage I or II disease, death or relapse occurred in more than half of the patients (8/15). Detailed analysis of our five cases revealed that, on immunohistochemistry, AFP+ EC was positive for SALL4 (4/5), AFP (3/5), and HNF1β (4/5) in >50% of neoplastic cells and negative for estrogen and progesterone receptors (5/5), PAX8 (4/5), and napsin A (5/5). Four cases exhibited aberrant p53 immunohistochemistry and were confirmed to harbor TP53 mutations by direct sequencing. No mutation was found in POLE, CTNNB1, or KRAS. In conclusion, AFP+ EC merits recognition as a distinct subtype of endometrial carcinoma, which occurs in 1.8% of endometrial carcinoma cases, are associated with TP53 abnormalities, exhibit lymphovascular infiltration, and can show distant metastasis even when treated in early stage.

High-grade endometrial carcinomas: Morphologic spectrum and molecular classification

High-grade endometrial carcinoma (HGEC) is a heterogeneous group of tumors with various morphologic, genetic, and clinical characteristics. Morphologically, HGEC includes high-grade endometrioid carcinoma, serous carcinoma, clear cell carcinoma, undifferentiated/dedifferentiated carcinoma, and carcinosarcoma. The morphologic classification has been used for prognostication and treatment decisions. However, patient management based on morphologic classification is limited by suboptimal interobserver reproducibility, variable clinical outcomes observed within the same histotype, and frequent discordant histotyping/grading between biopsy and hysterectomy specimens. Recent studies from The Cancer Genome Atlas (TCGA) Research Network established four distinct molecular subtypes: POLE-ultramutated, microsatellite unstable, copy number high, and copy number low groups. Compared to histotyping, the TCGA molecular classification appears superior in risk stratification. The best prognosis is seen in the POLE-ultramutated group and the worst in copy number high group, while the prognosis in the microsatellite unstable and copy number low groups is in between. The TCGA subtyping is more reproducible and shows a better concordance between endometrial biopsy and resection specimens. It has now become apparent that the molecular classification can supplement histotyping in patient management. This article provides an overview of the pathologic diagnosis/differential diagnosis of HGEC and the TCGA classification of endometrial cancers, with the clinical significance and applications of TCGA classification briefly discussed when appropriate.

Mesonephric-like Adenocarcinoma of the Uterine Corpus: Comprehensive Immunohistochemical Analyses Using Markers for Mesonephric, Endometrioid and Serous Tumors

Mesonephric-like adenocarcinoma (MLA) of the uterine corpus is a rare but distinct malignant tumor of the female genital tract, demonstrating a characteristic morphology and unique immunohistochemical profiles and molecular alterations. We conducted immunohistochemical staining (IHC) to make precise differential diagnoses of uterine MLAs from common histological subtypes of endometrial carcinomas. We collected 25 uterine MLAs and performed IHC for GATA3, TTF1, CD10, ER, PR, p16, p53, and HER2. Seventeen cases (68.0%) showed at least moderate nuclear GATA3 immunoreactivity in ≥25% of tumor cells. Most cases expressed TTF1 (17/21, 81.0%) and CD10 (luminal; 17/21, 81.0%). Heterogeneous TTF1 expression was noted in 12 cases. An inverse pattern of GATA3 and TTF1 staining was observed in eight cases (32.0%). Three cases (12.0%) showed moderate-to-strong ER expression in ≥25% of tumor cells, and two cases (8.0%) showed moderate-to-strong PR expression in ≥5% of tumor cells. These hormone receptor-positive MLAs varied in intensity and proportion of GATA3 staining. None of the 25 cases exhibited either diffuse and strong p16 expression or aberrant p53 expression. Five cases (20.0%) showed equivocal HER2 immunoreactivity (score 2+), but HER2 FISH confirmed that none of them exhibited HER2 gene amplification. In summary, a small subset of uterine MLAs displayed atypical IHC results: focal but strong expression of ER or PR, the complete absence of GATA3 immunoreactivity, the concurrent expression of mesonephric and hormone receptors, and the inverse pattern of GATA3 and TTF1 staining. These unusual immunophenotypes may complicate the differential diagnosis of MLA. Moreover, pathologists should be encouraged to interpret the IHC results cautiously.

A Timely Update of Immunohistochemistry and Molecular Classification in the Diagnosis and Risk Assessment of Endometrial Carcinomas

CONTEXT.—

Endometrial carcinoma is the most common gynecologic malignancy in the United States and has been traditionally classified based on histology. However, the distinction of certain histologic subtypes based on morphology is not uncommonly problematic, and as such, immunohistochemical study is often needed. Advances in comprehensive tumor sequencing have provided novel molecular profiles of endometrial carcinomas. Four distinct molecular subtypes with different prognostic values have been proposed by The Cancer Genome Atlas program: polymerase epsilon ultramutated, microsatellite instability hypermutated, copy number low (microsatellite stable or no specific molecular profile), and copy number high (serouslike, p53 mutant).

OBJECTIVE.—

To discuss the utilities of commonly used immunohistochemical markers for the classification of endometrial carcinomas and to review the recent advancements of The Cancer Genome Atlas molecular reclassification and their potential impact on treatment strategies.

DATA SOURCES.—

Literature review and authors' personal practice experience.

CONCLUSIONS.—

The current practice of classifying endometrial cancers is predominantly based on morphology. The use of ancillary testing, including immunohistochemistry, is helpful in the identification, differential diagnosis, and classification of these cancers. New developments such as molecular subtyping have provided insightful prognostic values for endometrial carcinomas. The proposed The Cancer Genome Atlas classification is poised to gain further prominence in guiding the prognostic evaluation for tailored treatment strategies in the near future.