Characterization of TP53-wildtype tubo-ovarian high-grade serous carcinomas: rare exceptions to the binary classification of ovarian serous carcinoma

Molecular Pathology of Ovarian Epithelial Neoplasms: Predictive, Prognostic, and Emerging Biomarkers

This review focuses on the diagnostic, prognostic, and predictive molecular biomarkers in ovarian epithelial neoplasms in the context of their morphologic classifications. Currently, most clinically actionable molecular findings are reported in high-grade serous carcinomas; however, the data on less common tumor types are rapidly accelerating. Overall, the advances in genomic knowledge over the last decade highlight the significance of integrating molecular findings with morphology in ovarian epithelial tumors for a wide-range of clinical applications, from assistance in diagnosis to predicting response to therapy.

Molecular characteristics of tubo-ovarian carcinosarcoma at different anatomic locations

Carcinosarcoma (CS) is an uncommon and clinically aggressive malignancy. The objective of the present study was to characterize the molecular features of CS at various anatomic locations, including serous effusions. Specimens (n = 32) consisted of 25 biopsies/surgical resection specimens and 7 serous effusions (6 peritoneal, 1 pleural) from 25 patients. Fresh-frozen cell pellets and surgical specimens underwent targeted next-generation sequencing covering 50 unique genes. A total of 31 mutations were found in 25 of the 32 tumors studied, of which 1 had 3 mutations, 4 had 2 different mutations, and 20 had a single mutation. The most common mutations were in TP53 (n = 25 in 24 tumors; 1 tumor with 2 different mutations), with less common mutations found in RB1 (n = 2), MET (n = 1), KRAS (n = 1), PTEN (n = 1), and KIT (n = 1). Patient-matched specimens harbored the same TP53 mutation. Tumors with no detected mutations were more common in serous effusion specimens (3/7; 43%) compared with surgical specimens (4/25; 16%). In conclusion, the molecular landscape of CS is dominated by TP53 mutations, reinforcing the observation that the majority of these tumors develop from high-grade serous carcinoma. Whether CS cells in serous effusions differ from their counterparts in solid lesions remains uncertain.

Diagnostic roles of PAX8 immunohistochemistry in ovarian tumors

OBJECTIVE

This study aimed to elucidate the diagnostic roles of PAX8 immunohistochemistry in various ovarian tumors.

METHODS

We searched through the PubMed database and selected the eligible studies to perform the meta-analysis. The PAX8 immunohistochemical expression rates of various ovarian tumors, including primary and metastatic carcinomas, were analyzed. In addition, the subgroup analysis based on tumor behaviors was performed.

RESULTS

The PAX8 expression rates were 0.056 (95% confidence interval [CI] 0.008-0.307), 0.400 (95% CI 0.228-0.600), 0.741 (95% CI 0.578-0.857), and 0.738 (95% CI 0.666-0.799) in normal ovary and benign, borderline, and malignant ovarian tumors, respectively. The PAX8 expression rates of serous and transitional cell carcinomas were 0.937 (95% CI 0.882-0.967) and 0.918 (95% CI 0.841-0.959). In addition, the PAX8 expression rate of mucinous carcinomas was 0.393 (95% CI 0.285-0.512). However, metastatic carcinomas showed a significantly lower PAX8 expression rate than primary ovarian cancers (P < 0.001 in the meta-regression test). In cytologic specimens, PAX8 expression rates of serous and endometrioid carcinomas were 0.905 (95% CI 0.832-0.948) and 0.714 (95% CI 0.327-0.928), respectively.

CONCLUSION

PAX8 expression rate was significantly higher in serous ovarian tumors than in mucinous ovarian tumors. In addition, PAX8 expression rates were significantly higher in primary ovarian cancers than in metastatic carcinomas.

A comprehensive immunohistochemical analysis of 26 markers in 250 cases of serous ovarian tumors

BACKGROUND

We examined a large cohort of serous tubo-ovarian tumors with 26 immunohistochemical markers, with the aim to assess their value for differential diagnosis and prognosis.

METHODS

Immunohistochemical analyses with 26 immunomarkers were performed on 250 primary tubo-ovarian tumors including 114 high grade serous carcinomas (HGSC), 97 low grade serous carcinomas (LGSC), and 39 serous borderline tumors (micropapillary variant, mSBT). The associations of overall positivity with clinicopathological characteristics were evaluated using the chi-squared test or Fisher's Exact test.

RESULTS

We found significantly different expression of p53, p16, ER, PR, PTEN, PAX2, Mammaglobin, RB1, Cyclin E1, stathmin, LMP2, L1CAM, CD44, and Ki67 in HGSCs compared to LGSCs. No significant differences were found between LGSC and mSBT. None of the other included markers (PAX8, ARID1A, HNF1B, Napsin A, CDX2, SATB2, MUC4, BRG1, AMACR, TTF1, BCOR, NTRK) showed any differences between the investigated serous tumors. Regarding the prognosis, only PR and stathmin showed a statistically significant prognostic meaning in LGSCs, with better overall survival (OS) and recurrence-free survival (RFS) in cases positive for PR, and worse outcome (RFS) for stathmin. None of the study markers showed prognostic significance in HGSCs.

CONCLUSION

We provided an extensive immunohistochemical analysis of serous ovarian/tubo-ovarian tumors. Although we found some differences in the expression of some markers in HGSCs compared to LGSCs, only p53, p16, and Ki67 seem to be useful in real diagnostic practice. We also suggested the best discriminative cut-off for Ki67 (10% of positive tumor cells) for distinguishing HGSC from LGSC. We found prognostic significance of PR and stathmin in LGSCs. Moreover, the high expression of stathmin could also be of predictive value in ovarian carcinomas as target-specific anti-stathmin effectors are potential therapeutic targets.

PTEN Deficiency in Tubo-Ovarian High-Grade Serous Carcinoma is Associated with Poor Progression-Free Survival and is Mutually Exclusive with CCNE1 Amplification

As a critical tumor suppressor, PTEN has gained much attention in cancer research. Emerging evidence suggests an association between PTEN status and clinical outcome in certain tumors, and may be predictive of response to several therapies. However, the significance of PTEN deficiency in tubo-ovarian high-grade serous carcinomas (HGSCs) is still poorly understood. We evaluated PTEN expression in HGSCs and determined its clinical relevance. A cohort of 76 HGSC specimens was profiled using tissue microarray. Immunohistochemistry (IHC) of PTEN, ER, PR, AR, CD8, FOXP3, and PD-L1 was performed. Targeted gene panel testing by massively parallel sequencing was performed in 51 cases. PTEN deficiency (complete or subclonal loss) detected by IHC was identified in 13 of the 62 HGSCs (21%) and was significantly correlated with reduced expression of ER and worse first progression-free survival (P < .05) but not with PD-L1 expression, the density of intratumoral T lymphocytes, or overall survival. In our cohort, tumor progression within 1 year of PARP inhibitor therapy was found more frequently in PTEN-deficient cases than in PTEN-intact cases (100% vs 52%). Molecular profiling showed that intragenic mutation or deletion was not the predominant mechanism for PTEN inactivation in HGSCs. In addition, CCNE1 amplification was found to be mutually exclusive with PTEN deficiency at both protein and DNA levels. An analysis of the genomic data from 1702 HGSC samples deposited with The Cancer Genome Atlas database obtained from cBioPortal confirmed the low rate of detection of PTEN gene alterations and the mutually exclusive nature of PTEN loss and CCNE1 amplification in HGSCs. These findings indicate that PTEN deficiency defines a distinct clinically significant subgroup of HGSCs with a tendency for ER negativity, wild-type CCNE1 status, inferior clinical outcomes, and potential drug resistance. These tumors may benefit from PI3K pathway inhibitors in combination with other ovarian cancer regimens, which deserves further investigation.

Homologous Recombination Deficiency and Ovarian Cancer Treatment Decisions: Practical Implications for Pathologists for Tumor Typing and Reporting

Clinical testing for homologous repair (HR) deficiency (HRD) in ovarian cancers has emerged as a means to tailor the use of poly(ADP-ribose)polymerase (PARP) inhibitor therapy to the patients most likely to respond. The currently available HRD tests evaluate tumor tissue for genomic evidence of impairment of the HR pathway of DNA damage repair, which, if present, renders the tumor vulnerable to PARP inhibitors in conjunction with platinum chemotherapy. Germline or somatic mutation of BRCA1/2 is a major contributor HRD. Thus, tubo-ovarian/peritoneal high-grade serous carcinoma (HGSC) is enriched by HRD. After highlighting the general concepts underlying HRD testing and PARP inhibitor therapy, this review discusses practical roles for pathologists to maximize the opportunities for eligible patients with ovarian cancer to benefit from HRD testing, chiefly by applying contemporary diagnostic criteria for ovarian cancer tumor typing and navigating through potential pitfalls of tumor types that may mimic HGSC but are unlikely to harbor HRD.

The Many Faces of Serous Neoplasms and Related Lesions of the Female Pelvis: A Review

Ovarian serous tumors and related lesions are one of the most common conditions of the female genital tract. While ovarian high-grade serous carcinoma carries high mortality and adverse prognosis, most other serous lesions have better clinical behavior. In recent years, significant progress has been made in understanding the nature and histogenesis of these lesions that has contributed to better and more precise clinical management. Most of the high-grade serous carcinomas involve the ovaries and/or peritoneum, although in most cases, their origin seems to be in the fallopian tube. This view is supported by the recognition of precursor lesions in the fallopian tube, such as p53 signature and serous tubular in situ carcinoma. This paper presents salient morphologic, immunohistochemical, and molecular data related to serous tumors and related lesions of the female pelvis and discusses the histogenetic interrelationship among these lesions in light of current knowledge.

Molecular mechanisms of platinum‑based chemotherapy resistance in ovarian cancer (Review)

Cisplatin is one of the most effective chemotherapy drugs for ovarian cancer, but resistance is common. The initial response to platinum‑based chemotherapy is as high as 80%, but in most advanced patients, final relapse and death are caused by acquired drug resistance. The development of resistance to therapy in ovarian cancer is a significant hindrance to therapeutic efficacy. The resistance of ovarian cancer cells to chemotherapeutic mechanisms is rather complex and includes multidrug resistance, DNA damage repair, cell metabolism, oxidative stress, cell cycle regulation, cancer stem cells, immunity, apoptotic pathways, autophagy and abnormal signaling pathways. The present review provided an update of recent developments in our understanding of the mechanisms of ovarian cancer platinum‑based chemotherapy resistance, discussed current and emerging approaches for targeting these patients and presented challenges associated with these approaches, with a focus on development and overcoming resistance.

Prognostic significance of intra-tumoral budding in high-grade serous ovarian carcinomas

Intra-tumoral budding (ITB) has been well demonstrated to be an independent risk factor for adverse outcomes in colorectal carcinoma. This study investigated the prognostic significance of ITB in high-grade serous ovarian carcinomas (HGSOCs). The medical records and slides of 84 SOCs, including 13 with neoadjuvant chemotherapy (NAC), were retrospectively reviewed. The histopathologic examination with scoring of p53 expression showed them to be 80 HGSOCs and 4 low-grade serous ovarian carcinomas (LGSOCs). ITB was found in 64 (80.0%) of the 80 HGSOCs and 1 (25.0%) of 4 LGSOCs. The presence of ITB in HGSOC was significantly correlated with a higher level of CA125, an advanced 2014 FIGO stage, the presence of Lymph node metastasis, and the presence of lymphovascular space invasion (LVSI). The median progression-free survival (PFS) was 18 months in patients with HGSOC with ITB and 36 months in patients with HGSOC without ITB (P = 0.006), and their median overall survival (OS) was 50 months and 60 months (P = 0.060). The multivariate analysis revealed that ITB was not an independent prognostic factor. ITB is a cost-effective prognostic indicator for patients with HGSOC and ITB in ovarian tumor tissue is considered a useful histological biomarker of the progression of HGSOCs.

The Potential Use of Mesenchymal Stem Cells and Their Derived Exosomes for Orthopedic Diseases Treatment

Musculoskeletal disorders (MSDs) are conditions that can affect muscles, bones, and joints. These disorders are very painful and severely limit patients' mobility and are more common in the elderly. MSCs are multipotent stem cells isolated from embryonic (such as the umbilical cord) and mature sources (such as adipose tissue and bone marrow). These cells can differentiate into various cells such as osteoblasts, adipocytes, chondrocytes, NP-like cells, Etc. Due to MSC characteristics such as immunomodulatory properties, ability to migrate to the site of injury, recruitment of cells involved in repair, production of growth factors, and large amount production of extracellular vesicles, these cells have been used in many regenerative-related medicine studies. Also, MSCs produce different types of EVs, such as exosomes, to the extracellular environment. Exosomes reflect MSCs' characteristics and do not have cell therapy-associated problems because they are cell-free. These vesicles carry proteins, nucleic acids, and lipids to the host cell and change their function. This review focuses on MSCs and MSCs exosomes' role in repairing dense connective tissues such as tendons, cartilage, invertebrate disc, bone fracture, and osteoporosis treatment.

Human iPSC-derived fallopian tube organoids with BRCA1 mutation recapitulate early-stage carcinogenesis

Germline pathogenic mutations in BReast CAncer (BRCA1) genes are thought to drive normal fallopian tube epithelial (FTE) cell transformation to high-grade serous ovarian cancer. No human models capture the sequence of events for disease initiation and progression. Here, we generate induced pluripotent stem cells (iPSCs) from healthy individuals and young ovarian cancer patients with germline pathogenic BRCA1 mutations (BRCA1^mut). Following differentiation into FTE organoids, BRCA1^mut lines exhibit cellular abnormalities consistent with neoplastic transformation compared to controls. BRCA1^mut organoids show an increased production of cancer-specific proteins and survival following transplantation into mice. Organoids from women with the most aggressive ovarian cancer show the greatest pathology, indicating the potential value to predict clinical severity prior to disease onset. These human FTE organoids from BRCA1^mut carriers provide a faithful physiological in vitro model of FTE lesion generation and early carcinogenesis. This platform can be used for personalized mechanistic and drug screening studies.

Yucer et al. generate a human BRCA1 mutant iPSC-derived fallopian tube organoid model, which recapitulates BRCA1 mutant ovarian carcinogenesis in vitro and shows tumors in vivo. This model provides a biologically relevant platform to validate drugs and a basis for personalized early detection and preventative strategies for women carrying BRCA1 mutations.

Somatic intronic TP53 c.375+5G mutations are a recurrent but under-recognized mode of TP53 inactivation

TP53 is one of the most ubiquitously altered genes in human cancer. The biological impact of rare variants, particularly those located within noncoding regions, remains poorly understood. From interrogation of clinical massively parallel sequencing data from over 55,000 tumors, which included 23,330 tumors with known TP53 mutations, TP53 intron 4 nucleotide substitutions at position c.375+5G were identified in 45 tumors (0.2% of TP53‐mutated cancers), comprising cancers of different organ sites. Loss‐of‐heterozygosity or a second‐hit somatic TP53 mutation was observed in 34 of 40 (85%) informative cases. RT‐PCR analysis showed the c.375+5G>T variant to be associated with aberrantly spliced TP53 mRNA transcripts with concomitant loss of the normal transcript. Immunohistochemical staining for p53 was performed on a representative subset of tumors with TP53 c.375+5G variants (n = 14), all of which showed loss of protein expression (100%; n = 13 complete loss, n = 1 subclonal loss). Our data are consistent with classification of TP53 c.375+5G variants as deleterious intronic mutations that interfere with proper mRNA splicing, ultimately resulting in loss of expression of functional p53 protein. The clinical scenario of a tumor with loss of p53 immunohistochemical staining, yet lacking a detectable TP53 exonic mutation, should therefore prompt consideration of splice‐altering intronic variants.

Molecular Pathology of Ovarian Epithelial Neoplasms: Predictive, Prognostic, and Emerging Biomarkers

This review focuses on the diagnostic, prognostic, and predictive molecular biomarkers in ovarian epithelial neoplasms in the context of their morphologic classifications. Currently, most clinically actionable molecular findings are reported in high-grade serous carcinomas; however, the data on less common tumor types are rapidly accelerating. Overall, the advances in genomic knowledge over the last decade highlight the significance of integrating molecular findings with morphology in ovarian epithelial tumors for a wide-range of clinical applications, from assistance in diagnosis to predicting response to therapy.

MDM2 amplification in malignant Brenner tumors may play a role in progression to malignancy and aid in separation from urothelial and other ovarian carcinomas

Malignant Brenner tumor (MBT) is diagnosed in the setting of invasive high-grade carcinoma with urothelial-like morphology and the presence of an adjacent benign Brenner tumor (BBT) or borderline Brenner tumor (BLBT). MDM2 amplification was recently detected by next-generation sequencing on a small number of MBTs, potentially significant for future targeted therapy. Experience is limited, however, and evaluation of widely available MDM2 immunohistochemistry (IHC) has not been performed to determine clinical utility. After confirming all diagnoses morphologically and immunohistochemically, we performed MDM2 IHC on 4 MBTs, 3 BLBTs, 26 BBTs, 142 high-grade serous carcinomas (HGSC), 6 ovarian endometrioid carcinomas (OEC) with urothelial-like morphology, and 49 high-grade urothelial carcinomas (HGUC). MDM2 IHC was considered positive with diffuse (>25%) nuclear reactivity; in cases of patchy staining (10-25% nuclear reactivity), MDM2 was considered equivocal. Positive staining in <10% of cells was considered negative. In cases with positive or equivocal staining, MDM2 amplification was evaluated by fluorescence in-situ hybridization (FISH). Three MBTs (75%) showed diffuse nuclear reactivity for MDM2 by IHC, a finding corroborated by amplification of MDM2 in all three cases. One MBT and 2 BLBTs showed equivocal MDM2 IHC, but all three were negative for MDM2 amplification. The final BLBT, as well as all BBTs, HGSC, OEC, and HGUC, were negative for MDM2. In conclusion, our limited cohort confirms MDM2 amplification in MBT and suggests that MDM2 IHC may have an influence in rare diagnostically challenging cases.

Mutated p53 in HGSC-From a Common Mutation to a Target for Therapy

Simple Summary

Ovarian high-grade serous cancer (HGSC), the most common and the deadliest subtype of epithelial ovarian cancer, is characterized by frequent mutations in the TP53 tumor suppressor gene, encoding for the p53 protein in nearly 100% of cases. This makes p53 the focus of many studies trying to understand its role in HGSC. The aim of our review paper is to provide updates on the latest findings related to the role of mutant p53 in HGSC. This includes the clinical outcomes of TP53 mutations in HGSC, upstream regulators and downstream effectors of p53, its function in the earliest stages of HGSC development and in the interplay between the tumor cells and their microenvironment. We summarize with the likelihood of p53 mutants to serve as biomarkers for early diagnosis and as targets for therapy in HGSC.

Abstract

Mutations in tumor suppressor gene TP53, encoding for the p53 protein, are the most ubiquitous genetic variation in human ovarian HGSC, the most prevalent and lethal histologic subtype of epithelial ovarian cancer (EOC). The majority of TP53 mutations are missense mutations, leading to loss of tumor suppressive function of p53 and gain of new oncogenic functions. This review presents the clinical relevance of TP53 mutations in HGSC, elaborating on several recently identified upstream regulators of mutant p53 that control its expression and downstream target genes that mediate its roles in the disease. TP53 mutations are the earliest genetic alterations during HGSC pathogenesis, and we summarize current information related to p53 function in the pathogenesis of HGSC. The role of p53 is cell autonomous, and in the interaction between cancer cells and its microenvironment. We discuss the reduction in p53 expression levels in tumor associated fibroblasts that promotes cancer progression, and the role of mutated p53 in the interaction between the tumor and its microenvironment. Lastly, we discuss the potential of TP53 mutations to serve as diagnostic biomarkers and detail some more advanced efforts to use mutated p53 as a therapeutic target in HGSC.

Can TP53 variant negative be high-grade serous ovarian carcinoma? A case series

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TP53 variant negative high-grade serous ovarian cancer is rare and can still show p53 abnormal immunohistochemistry.

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Diagnostic and therapeutic considerations include pathologic, molecular and clinical domains.

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Genetic reassessment through more comprehensive assays should be considered to ensure no missed rare or complex variants.

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Presence of BRCA mutations can occur in TP53 variant high-grade serous ovarian cancer.

Immunohistochemical Biomarkers as a Surrogate of Molecular Analysis in Ovarian Carcinomas: A Review of the Literature

The term "ovarian carcinoma" encompasses at least five different malignant neoplasms: high-grade serous carcinoma, low-grade serous carcinoma, endometrioid carcinoma, mucinous carcinoma, and clear cell carcinoma. These five histotypes demonstrated distinctive histological, molecular, and clinical features. The rise of novel target therapies and of a tailored oncological approach has demanded an integrated multidisciplinary approach in the setting of ovarian carcinoma. The need to implement a molecular-based classification in the worldwide diagnostic and therapeutic setting of ovarian cancer demanded a search for easy-to-use and cost-effective molecular-surrogate biomarkers, relying particularly on immunohistochemical analysis. The present review focuses on the role of immunohistochemistry as a surrogate of molecular analysis in the everyday diagnostic approach to ovarian carcinomas.