Mucinous tumours of the ovary

Update on Prognostic and Predictive Markers in Mucinous Ovarian Cancer

This review includes state-of-the-art prognostic and predictive factors of mucinous ovarian cancer (MOC), a rare tumor. Clinical, pathological, and molecular features and treatment options according to prognosis are comprehensively discussed. Different clinical implications of MOC are described according to the The International Federation of Gynecology and Obstetrics (FIGO) stage: early MOC (stage I-II) and advanced MOC (stage III-IV). Early MOC is characterized by a good prognosis. Surgery is the mainstay of treatment. Fertility-sparing surgery could be performed in patients who wish to become pregnant and that present low recurrence risk of disease. Adjuvant chemotherapy is not recommended, except in patients with high-risk clinical and pathological features. Regarding the histological features, an infiltrative growth pattern is the major prognostic factor of MOC. Furthermore, novel molecular biomarkers are emerging for tailored management of early-stage MOC. In contrast, advanced MOC is characterized by poor survival. Radical surgery is the cornerstone of treatment and adjuvant chemotherapy is recommended, although the efficacy is limited by the intrinsic chemoresistance of these tumors. Several molecular hallmarks of advanced MOC have been described in recent years (e.g., HER2 amplification, distinct methylation profiles, peculiar immunological microenvironment), but target therapy for these rare tumors is not available yet.

Trefoil factor family proteins as potential diagnostic markers for mucinous invasive ovarian carcinoma

Introduction

Ovarian cancer (OC) is the leading cause of gynecological cancer-related death. Of the main OC histologic subtypes, invasive mucinous carcinomas (MC) account for only 3% of OC cases and are frequently associated with favorable prognosis. Nevertheless, MCs differ greatly from the other OC histotypes in clinical, pathological, and biological behavior. However, the origin and molecular pathogenesis of MC are not yet fully understood. Therefore, identification of novel diagnostic markers could potentially facilitate early diagnosis of OC, particularly the MC histotype, thereby leading to the development of histotype-specific treatment regimens and improved survival rates.

Methods

In the present study, Trefoil factor gene family members (TFF1, TFF2 and TFF3) were identified as MC histotype-specific biomarkers using RNA sequencing (RNA-seq) data for 95 stage I-II OCs. The diagnostic value of TFF1, TFF2 and TFF3 was then evaluated by immunohistochemistry on 206 stage I-II OCs stratified by histotype (high-grade serous carcinoma [HGSC], endometrioid carcinoma [EC], clear cell carcinoma [CCC], and MC).

Results

We showed significantly elevated intracytoplasmic protein expression levels for TFF1, TFF2 and TFF3 in MC samples, thereby revealing an association between expression of Trefoil factor gene family members and the MC histotype. Taken together, these findings suggest that the TFF proteins may play a pivotal role in tumor initiation and progression for the MC histotype.

Conclusion

Taken together, these findings suggest that the TFF proteins may play a pivotal role in tumor initiation and progression for the MC histotype. Moreover, these novel histotype-specific diagnostic biomarkers may not only improve patient stratification of early-stage ovarian carcinomas but may also be candidates for the development of molecular targeted therapies.

Options for the Treatment of Mucinous Ovarian Carcinoma

OPINION STATEMENT

Complete surgical resection is the gold-standard treatment for all mucinous ovarian carcinoma (MOC) cases. Advanced-stage disease is often additionally treated with adjuvant platinum-based chemotherapy; however, these were developed largely against the more common high-grade serous ovarian carcinoma and have low efficacy in treating MOC. More effective therapeutics are needed to treat late-stage and platinum-resistant tumors; however, traditional drug development and clinical trial paradigms are a major challenge for such a rare disease. New approaches to support evidence-based treatment decisions are required, such as registry trials. Recently, a number of targeted therapies have emerged as viable treatment options in other cancer types, and for some of these, the actionable tumor mutations are also seen in MOC. Thus, a promising alternative approach to provide benefit to current MOC patients involves DNA sequencing to identify a tumor's unique mutational profile and allow matching to available targeted agents. Such a pipeline can involve special approval to administer a drug already approved for clinical use in other cancer types to a given MOC patient, or their inclusion in existing ongoing clinical trials, such as basket trials encompassing patients with tumors from a range of anatomical sites. Implementation of such personalized medicine can be boosted using improved pre-clinical models, where through a clinical research collaboration a patient's own tumor cells can be used to a test a range of putative therapies prior to administration in the clinic, enabling selection of the available pharmaceutical/s that give any given patient the best possible chance of cancer remission.

The Protein Landscape of Mucinous Ovarian Cancer: Towards a Theranostic

MOC is a rare histotype of epithelial ovarian cancer, and current management options are inadequate for the treatment of late stage or recurrent disease. A shift towards personalised medicines in ovarian cancer is being observed, with trials targeting specific molecular pathways, however, MOC lags due to its rarity. Theranostics is a rapidly evolving category of personalised medicine, encompassing both a diagnostic and therapeutic approach by recognising targets that are expressed highly in tumour tissue in order to deliver a therapeutic payload. The present review evaluates the protein landscape of MOC in recent immunohistochemical- and proteomic-based research, aiming to identify potential candidates for theranostic application. Fourteen proteins were selected based on cell membrane localisation: HER2, EGFR, FOLR1, RAC1, GPR158, CEACAM6, MUC16, PD-L1, NHE1, CEACAM5, MUC1, ACE2, GP2, and PTPRH. Optimal proteins to target using theranostic agents must exhibit high membrane expression on cancerous tissue with low expression on healthy tissue to afford improved disease outcomes with minimal off-target effects and toxicities. We provide guidelines to consider in the selection of a theranostic target for MOC and suggest future directions in evaluating the results of this review.

The utility of PAX8 and SATB2 immunohistochemical stains in distinguishing ovarian mucinous neoplasms from colonic and appendiceal mucinous neoplasm

Objectives

It is challenging to distinguish between primary ovarian mucinous tumors and metastatic mucinous neoplasms from the lower gastrointestinal tract, including appendiceal tumors. A combination of PAX8 and SATB2 immunohistochemical stains can be used as a diagnostic tool to distinguish between these cases.

Results

Immunostaining for SATB2, PAX8, CK7, CK20 and CDX2 was performed on 50 ovarian mucinous neoplasms (OMN) (39 cystadenomas, 4 borderline and 7 adenocarcinomas), 63 mucinous colorectal carcinoma (CRC), and 9 appendiceal mucinous neoplasms (AMN) [8 low grade appendiceal mucinous neoplasms (LAMN) and 1 adenocarcinoma]. PAX8 was positive in 32% of OMN and negative in all CRC and AMN cases. SATB2 was expressed in 2.0% of OMN, 77.8% of AMN, and 49.2% of CRC cases. CK7 was positive in 78.0% of OMN, 33.3% of AMN, and 9.5% of CRC cases. CK20 was expressed in 24.0% of OMN, 88.9% of OMN, and 87.3% of CRC cases. CDX2 was positive in 14.0% of OMN, 100% of AMN, and 90.5% of CRC cases. PAX8 can differentiate between OMN and AMN with high specificity but low sensitivity. CDX2 is the most sensitive marker for CRC and AMN, whereas SATB2 has better specificity.

PRKRA/PACT Expression Promotes Chemoresistance of Mucinous Ovarian Cancer

For mucinous ovarian cancer (MOC), standard platinum-based therapy is largely ineffective. We sought to identify possible mechanisms of oxaliplatin resistance of MOC and develop strategies to overcome this resistance. A kinome-based siRNA library screen was carried out using human MOC cells to identify novel targets to enhance the efficacy of chemotherapy. In vitro and in vivo validations of antitumor effects were performed using mouse MOC models. Specifically, the role of PRKRA/PACT in oxaliplatin resistance was interrogated. We focused on PRKRA, a known activator of PKR kinase, and its encoded protein PACT because it was one of the five most significantly downregulated genes in the siRNA screen. In orthotopic mouse models of MOC, we observed a significant antitumor effect of PRKRA siRNA plus oxaliplatin. In addition, expression of miR-515-3p was regulated by PACT-Dicer interaction, and miR-515-3p increased the sensitivity of MOC to oxaliplatin. Mechanistically, miR-515-3p regulated chemosensitivity, in part, by targeting AXL. The PRKRA/PACT axis represents an important therapeutic target in MOC to enhance sensitivity to oxaliplatin.

Recent Insights into Mucinous Ovarian Carcinoma

Ovarian mucinous tumors represent a group of rare neoplasms with a still undefined cell of origin but with an apparent progression from benign to borderline to carcinoma. Even though these tumors are different from the other histological subtypes of epithelial ovarian neoplasms, they are still treated with a similar chemotherapeutic approach. Here, we review its pathogenesis, molecular alterations, (differential) diagnosis, clinical presentation and current treatment, and how recent molecular and biological information on this tumor might lead to better and more specific clinical management of patients with mucinous ovarian carcinoma.

Mucinous epithelial ovarian carcinoma

Mucinous tumours involving the ovary may be benign, borderline, or malignant. Malignant tumours may be primary or metastatic. Differentiation between primary and metastatic involvement of the ovary is critical for optimal patient management. Even among skilled pathologists, this distinction can be problematic, as can the distinction between borderline ovarian tumour of intestinal type and well-differentiated invasive primary mucinous ovarian carcinoma. Primary invasive mucinous ovarian carcinoma and mucinous carcinoma metastatic to the ovary do have distinct patterns of macroscopic and microscopic involvement which will reveal the correct diagnosis in many cases. There are also well-recognized patterns of immunohistochemical staining that can further assist in this differentiation. As a result of the application of these histopathological techniques, the incidence of primary invasive mucinous epithelial carcinoma has fallen over recent years from ∼12% to ∼3%. However, even in recent multicentre clinical trials such as GOG 182, expert pathological review suggests that ∼60% of tumours originally classified as primary invasive mucinous carcinomas were in fact metastatic tumours to the ovary. Review of outcome data for patients with mucinous carcinoma entered into multicentre trials suggests that this subtype of disease has a particularly poor prognosis in comparison with other subtypes of ovarian carcinoma. Historically, patients with mucinous epithelial ovarian carcinoma (mEOC) have been treated in the same way as other subtypes of ovarian carcinoma. While there is undoubtedly a response rate to platinum-based chemotherapy, retrospective reviews of individual centre experience suggest that this is substantially lower than for high-grade papillary serous carcinoma and in the order of only 30%-40%. The mEOC trial was established to investigate the possibility that the combination of capecitabine and oxaliplatin (chemotherapy drugs more commonly used in colorectal carcinoma) may be superior to conventional carboplatin and paclitaxel chemotherapy. In a 2 × 2 factorial design, there was also a randomization to bevacizumab. Unfortunately, this trial closed early, 5 years after initiation having recruited just 50 of a proposed 322 patients. mEOC is now characterized as a type I tumour with an identifiable stepwise progression from a premalignant lesion, through non-invasive, to invasive malignancy. Molecular characterization of mEOC reveals it to be distinct from other subtypes of the disease with a KRAS mutation occurring in 40%-50% of patients. Other gene abnormalities including HER2 amplification in ∼19% also occur. This raises the possibility of the use of targeted molecular therapies which with molecular analysis of individual patient tumours could form the basis of a future clinical trial. It is, however, clear that if trials are to be conducted in this rare subtype of disease, they will need to be truly international in nature and carefully designed, possibly using an adaptive stepwise approach and will require an appropriate level of funding with a realistic assessment of likely recruitment. Associated translational research will clearly be essential.

Mucinous ovarian cancer: A therapeutic review

Mucinous ovarian cancer represents approximately 3% of epithelial ovarian cancers (EOC). Despite this seemingly low prevalence, it remains a diagnostic and therapeutic conundrum that has resulted in numerous attempts to adopt novel strategies in managing this disease. Anecdotally, there has been a prevailing notion that established gold standard systemic regimens should be substituted for those utilised in cancers such as gastrointestinal (GI) malignancies; tumours that share more biological similarities than other EOC subtypes. This review summarises the plethora of small studies which have adopted this philosophy and influenced the design of the multinational GOG142 study, which was ultimately terminated due to poor accrual. To date, there is a paucity of evidence to support delivering 'GI style' chemotherapy for mucinous ovarian cancer over and above carboplatin-paclitaxel doublet therapy. Hence there is an urge to develop studies focused on targeted therapeutic agents driven by refined mutational analysis and conducted within the context of harmonised international collaborations.

Early stage primary ovarian mucinous carcinoma: Outcome-based clinicopathological study in comparison with serous carcinoma

OBJECTIVE

To compare clinicopathological characteristics and survival rates between patients with primary ovarian mucinous carcinoma and those with primary ovarian serous carcinoma.

METHODS

This retrospective study reviewed archival tumour specimens, originally diagnosed as primary ovarian mucinous carcinoma, using refined histological criteria. All patients were contacted to establish survival status. Clinicopathological characteristics and patient survival data were compared with a group of control patients with primary ovarian serous carcinoma.

RESULTS

Of the 33 patients originally diagnosed with primary ovarian mucinous carcinoma, this diagnosis was only confirmed in 18. Primary ovarian mucinous carcinoma was more commonly associated with early International Federation of Gynecology and Obstetrics tumour stages and low-grade histology than primary ovarian serous carcinoma. Patients with primary ovarian mucinous carcinoma had a significantly higher overall 5-year survival rate than those with primary ovarian serous carcinoma (12/12 [100%] versus 14/24 [58%]). Kaplan-Meier survival plots demonstrated that patients with primary ovarian mucinous carcinoma had a survival advantage over patients with primary ovarian serous carcinoma.

CONCLUSIONS

Primary ovarian mucinous carcinomas are frequently low-grade, stage I tumours and have an excellent prognosis.

Molecular biology of gynecological cancer

Cancer is a pathological condition in which the balance between cell growth and death is disordered. Various molecules have been reported to be involved in the oncogenic process of invasion, metastasis and resistance to treatment. An exponential growth in the collection of genomic and proteomic data in the past 20 years has provided major advances in understanding the molecular mechanisms of human cancer, which has been applied to diagnostic and treatment strategies. Targeted therapies have been developed and adopted, particularly for advanced, refractory or recurrent cancers, depending on individual molecular profiles. The aim of the present review is to provide a report of the current literature regarding the molecular biology of gynecological cancers.

Medical treatment of early stage and rare histological variants of epithelial ovarian cancer

Epithelial ovarian cancer is often considered a single pathological entity, but increasing evidence suggests that it is rather a group of different neoplasms, each with unique pathological characteristics, molecular features, and clinical behaviours. This heterogeneity accounts for the different sensitivity to antineoplastic drugs and makes the treatment of ovarian tumours a challenge. For early-stage disease, as well as for heavily pre-treated patients with recurrent ovarian cancer, the benefit of chemotherapy remains uncertain. Clear-cell, mucinous, low-grade serous, and endometrioid carcinomas show different molecular characteristics, which require different therapeutic approaches. In the era of personalised cancer medicine, understanding the pathogenesis and the genetic background of each subtype of epithelial ovarian tumour may lead to a tailored therapy, maximising the benefits of specific treatments and possibly reducing the side effects. Furthermore, personal factors, such as the patient's performance status, should be taken into account in the management of ovarian cancer, with the aim of safeguarding the patients' quality of life.

Mucinous tumors of the ovary: current thoughts on diagnosis and management

Mucinous tumors of the ovary represent a spectrum of neoplastic disorders, including benign mucinous cystadenoma, pseudomyxoma peritonei, mucinous tumors of low malignant potential (borderline), and invasive mucinous ovarian carcinoma. These tumors are related closely to each other and are distinct from other histologic subtypes of epithelial ovarian neoplasms from a clinical, histologic, and molecular standpoint. A continuum appears to be present from benign to borderline to malignant, which is different from other types of epithelial ovarian cancer. Mutational profiles are also distinct, as KRAS mutations are common, but p53 and BRCA mutations are infrequent. These characteristics lead to specific biologic behavior and guide both clinical management and research efforts in patients with mucinous ovarian tumors.

Gynecologic Cancer InterGroup (GCIG) consensus review for mucinous ovarian carcinoma

Mucinous carcinomas of the ovary can be primary or metastatic in origin. Improvements in the pathological diagnosis have increased the ability to distinguish between primary and metastatic ovarian cancers and shown that primary mucinous carcinomas are a rare subtype of ovarian cancer. Most tumors are diagnosed at an early stage, and the prognosis after surgery is good. Advanced or recurrent mucinous carcinoma of the ovary responds poorly to current cytotoxic treatments, and the prognosis is poor. Here, we review the guidelines for surgery and the results of treatment of advanced and recurrent disease. Chemotherapy with platinum and paclitaxel is currently used to treat advanced disease, but the effect of these drugs is modest, and new treatments are needed.

Serum CA19-9 as a predictor of malignancy in primary ovarian mucinous tumors: a matched case-control study

Background

This study was designed to investigate the clinical characteristics correlated with serum CA19-9 elevation in primary mucinous ovarian tumors and to evaluate the role of serum CA19-9 in predicting borderline or malignant tumors.

Material/Methods

We retrospectively identified 27 women with pathologically-confirmed primary ovarian mucinous neoplasms (16 borderline and 11 malignant), who had been preoperatively checked for serum CA19-9 and CA125 levels. The control group was established by 1:2 matching for age among all women with pathologically-confirmed benign mucinous tumors over the same time period. The associations of the serum CA19-9 elevation and clinical characteristics, including tumor pathology, were evaluated.

Results

Serum CA19-9 was more frequently elevated in borderline or malignant than benign tumors (57.9% vs. 16.7%, P=0.001), although the mean value of serum CA19-9 was not significantly different among histological subtypes. CA19-9 elevation was correlated with large tumor size (largest diameter ≥15 cm; p=0.028), serum CA125 elevation (p=0.006), and tumor pathology (borderline or malignant tumors; p=0.001). Other clinical characteristics, including parity, menopause, bilateral tumor involvement, and torsion were not correlated with CA19-9 elevation. Multivariate analysis revealed that tumor pathology was the only independent factor for CA19-9 elevation in primary ovarian mucinous tumors (odds ratio 3.842, 95% CI 1.277–11.558, p=0.017). Interestingly, subgroup analysis in women with normal serum CA 125 level revealed that CA19-9 was significantly correlated with borderline and malignant tumors but not with benign tumors (odds ratio 6.3, 95% CI 1.438–19.648, p=0.014).

Conclusions

Serum CA19-9 can be a useful complementary marker in differentiating benign from borderline or malignant mucinous tumors in the ovaries, particularly when serum CA125 level is not elevated.

Targeting SRC and tubulin in mucinous ovarian carcinoma

PURPOSE

To investigate the antitumor effects of targeting Src and tubulin in mucinous ovarian carcinoma.

EXPERIMENTAL DESIGN

The in vitro and in vivo effects and molecular mechanisms of KX-01, which inhibits Src pathway and tubulin polymerization, were examined in mucinous ovarian cancer models.

RESULTS

In vitro studies using RMUG-S and RMUG-L cell lines showed that KX-01 inhibited cell proliferation, induced apoptosis, arrested the cell cycle at the G2-M phase, and enhanced the cytotoxicity of oxaliplatin in the KX-01-sensitive cell line, RMUG-S. In vivo studies showed that KX-01 significantly decreased tumor burden in RMUG-S and RMUG-L mouse models relative to untreated controls, and the effects were greater when KX-01 was combined with oxaliplatin. KX-01 alone and in combination with oxaliplatin significantly inhibited tumor growth by reducing cell proliferation and inducing apoptosis in vivo. PTEN knock-in experiments in RMUG-L cells showed improved response to KX-01. Reverse phase protein array analysis showed that in addition to blocking downstream molecules of Src family kinases, KX-01 also activated acute stress-inducing molecules.

CONCLUSION

Our results showed that targeting both the Src pathway and tubulin with KX-01 significantly inhibited tumor growth in preclinical mucinous ovarian cancer models, suggesting that this may be a promising therapeutic approach for patients with mucinous ovarian carcinoma.

Antibody-based immunotherapy for ovarian cancer: where are we at?

Cytoreductive surgery and chemotherapy continue to be the mainstay of ovarian cancer treatment. However, as mortality from advanced ovarian cancer remains very high, novel therapies are required to be integrated into existing treatment regimens. Immunotherapy represents an alternative and rational therapeutic approach for ovarian cancer based on a body of evidence supporting a protective role of the immune system against these cancers, and on the clinical success of immunotherapy in other malignancies. Whether or not immunotherapy will have a role in the future management of ovarian cancer is too early to tell, but research in this field is active. This review will discuss recent clinical developments of selected immunotherapies for ovarian cancer which fulfil the following criteria: (i) they are antibody-based, (ii) target a distinct immunological pathway, and (iii) have reached the clinical trial stage. Specifically, the focus is on Catumaxomab (anti-EpCAM×anti-CD3), Abagovomab, Oregovomab (anti-CA125), Daclizumab (anti-CD25), Ipilimumab (anti-CTLA-4), and MXD-1105 (anti-PD-L1). Catumaxomab has reached phase III clinical trials and exhibits promise with reports, showing that it can cause a significant and sustained reduction in ascites. Phase I-III clinical trials continue to be conducted on the other antibodies, some of which have had encouraging reports. We will also provide our perspective on the future of immunotherapy for ovarian cancer, and how it may be best employed in treatment regimens.

Ovarian cancer: in search of better marker systems based on DNA repair defects

Ovarian cancer is the fifth most common female cancer in the Western world, and the deadliest gynecological malignancy. The overall poor prognosis for ovarian cancer patients is a consequence of aggressive biological behavior and a lack of adequate diagnostic tools for early detection. In fact, approximately 70% of all patients with epithelial ovarian cancer are diagnosed at advanced tumor stages. These facts highlight a significant clinical need for reliable and accurate detection methods for ovarian cancer, especially for patients at high risk. Because CA125 has not achieved satisfactory sensitivity and specificity in detecting ovarian cancer, numerous efforts, including those based on single and combined molecule detection and “omics” approaches, have been made to identify new biomarkers. Intriguingly, more than 10% of all ovarian cancer cases are of familial origin. BRCA1 and BRCA2 germline mutations are the most common genetic defects underlying hereditary ovarian cancer, which is why ovarian cancer risk assessment in developed countries, aside from pedigree analysis, relies on genetic testing of BRCA1 and BRCA2. Because not only BRCA1 and BRCA2 but also other susceptibility genes are tightly linked with ovarian cancer-specific DNA repair defects, another possible approach for defining susceptibility might be patient cell-based functional testing, a concept for which support came from a recent case-control study. This principle would be applicable to risk assessment and the prediction of responsiveness to conventional regimens involving platinum-based drugs and targeted therapies involving poly (ADP-ribose) polymerase (PARP) inhibitors.