Sorafenib efficacy in ovarian clear cell carcinoma revealed by transcriptome profiling

Predicting Prognosis and Platinum Resistance in Ovarian Cancer: Role of Immunohistochemistry Biomarkers

Ovarian cancer is a lethal reproductive tumour affecting women worldwide. The advancement in presentation and occurrence of chemoresistance are the key factors for poor survival among ovarian cancer women. Surgical debulking was the mainstay of systemic treatment for ovarian cancer, which was followed by a successful start to platinum-based chemotherapy. However, most women develop platinum resistance and relapse within six months of receiving first-line treatment. Thus, there is a great need to identify biomarkers to predict platinum resistance before enrolment into chemotherapy, which would facilitate individualized targeted therapy for these subgroups of patients to ensure better survival and an improved quality of life and overall outcome. Harnessing the immune response through immunotherapy approaches has changed the treatment way for patients with cancer. The immune outline has emerged as a beneficial tool for recognizing predictive and prognostic biomarkers clinically. Studying the tumour microenvironment (TME) of ovarian cancer tissue may provide awareness of actionable targets for enhancing chemotherapy outcomes and quality of life. This review analyses the relevance of immunohistochemistry biomarkers as prognostic biomarkers in predicting chemotherapy resistance and improving the quality of life in ovarian cancer.

Sintilimab combined with bevacizumab in relapsed/persistent ovarian clear cell carcinoma (INOVA): an investigator-initiated, multicentre clinical trial-a study protocol of clinical trial

BACKGROUND

Ovarian clear cell carcinoma (OCCC) has an abysmal prognosis with a median overall survival (OS) of 25.3 months because of a low response to chemotherapy. The 5-year disease-specific survival rate after recurrence is 13.2%, with more than two-thirds of the patients dying within a year. Therefore, it is urgent to explore new therapeutic options for OCCC. Based on the characteristic immune-suppressive tumour microenvironment derived from the gene expression profile of OCCC, the combination of immunoantiangiogenesis therapy might have certain efficacy in recurrent/persistent OCCC. This trial aims to evaluate the efficacy and safety of sintilimab and bevacizumab in patients who have failed platinum-containing chemotherapy with recurrent or persistent OCCC.

METHOD AND ANALYSIS

In this multicentre, single-arm, open-label, investigator-initiated clinical trial, 38 patients will be assigned to receive sintilimab 200 mg plus bevacizumab 15 mg/kg every 3 weeks. The eligibility criteria include histologically diagnosed patients with recurrent or persistent OCCC who have been previously treated with at least one-line platinum-containing chemotherapy; patients with Eastern Cooperative Oncology Group (ECOG) performance status 0-2 with an expected survival greater than 12 weeks. The exclusion criteria include patients previously treated with immune checkpoint inhibitor and patients with contraindications of bevacizumab and sintilimab. The primary endpoint is the objective response rate. The secondary endpoints are progression-free survival, time to response, duration of response, disease control rate, OS, safety and quality of life. Statistical significance was defined as p<0.05.

ETHICS AND DISSEMINATION

This trial was approved by the Research Ethics Commission of Tongji Medical College of Huazhong University of Science and Technology (2020-S337). The protocol of this study is registered at www.

CLINICALTRIALS

gov. The trial results will be published in peer-reviewed journals and at conferences.

TRIAL REGISTRATION NUMBER

NCT04735861; Clinicaltrials. gov.

Frequent DYSF rare variants/mutations in 152 Han Chinese samples with ovarian endometriosis

PURPOSE

Endometriosis is a common chronic gynecological disease greatly affecting women health. Prior studies have implicated that dysferlin (DYSF) aberration might be involved in the pathogenesis of ovarian endometriosis. In the present study, we explore the potential presence of DYSF mutations in a total of 152 Han Chinese samples with ovarian endometriosis.

METHODS

We analyze the potential presence of DYSF mutations by direct DNA sequencing.

RESULTS

A total of seven rare variants/mutations in the DYSF gene in 10 out of 152 samples (6.6%) were identified, including 5 rare variants and 2 novel mutations. For the 5 rare variants, p.R334W and p.G941S existed in 2 samples, p.R865W, p.R1173H and p.G1531S existed in single sample, respectively; for the two novel mutations, p.W352* and p.I1642F, they were identified in three patients. These rare variants/mutations were absent or existed at extremely low frequency either in our 1006 local control women without endometriosis, or in the China Metabolic Analytics Project (ChinaMAP) and Genome Aggregation Database (gnomAD) databases. Evolutionary conservation analysis results suggested that all of these rare variants/mutations were evolutionarily conserved among 11 vertebrate species from Human to Fox. Furthermore, in silico analysis results suggested these rare variants/mutations were disease-causing. Nevertheless, we find no significant association between DYSF rare variants/mutations and the clinical features in our patients. To our knowledge, this is the first report revealing frequent DYSF mutations in ovarian endometriosis.

CONCLUSION

We identified a high frequency of DYSF rare variants/mutations in ovarian endometriosis for the first time. This study suggests a new correlation between DYSF rare variants/mutations and ovarian endometriosis, implicating DYSF rare variants/mutations might be positively involved in the pathogenesis of ovarian endometriosis.

Genomics to immunotherapy of ovarian clear cell carcinoma: Unique opportunities for management

Ovarian clear cell carcinoma (OCCC) is distinctive from other histological types of epithelial ovarian cancer, with genetic/epigenetic alterations, a specific immune-related molecular profile, and epidemiologic associations with ethnicity and endometriosis. These findings allow for the exploration of unique and specific treatments for OCCC. Two major mutated genes in OCCC are PIK3CA and ARID1A, which are frequently coexistent with each other. Other genes' alterations also contribute to activation of the PI3K (e.g. PIK3R1 and PTEN) and dysregulation of the chromatin remodeling complex (e.g. ARID1B, and SMARKA4). Although the number of focal copy number variations is small in OCCC, amplification is recurrently detected at chromosome 20q13.2 (including ZNF217), 8q, and 17q. Both expression and methylation profiling highlight the significance of adjustments to oxidative stress and inflammation. In particular, up-regulation of HNF-1β resulting from hypomethylation contributes to the switch from anaerobic to aerobic glucose metabolism. Additionally, up-regulation of HNF-1β activates STAT3 and NF-κB signaling, and leads to immune suppression via production of IL-6 and IL-8. Immune suppression may also be induced by the increased expression of PD-1, Tim-3 and LAG3. Mismatch repair deficient (microsatellite instable) tumors as found in Lynch syndrome also induce immune suppression in some OCCC. In a recent phase II clinical trial in heavily-treated platinum-resistant ovarian cancer, two out of twenty cases with a complete response to the anti-PD-1 antibody, nivolumab, were OCCC subtypes. Thus, the immune-suppressive state resulting from both genetic alterations and the unique tumor microenvironment may be associated with sensitivity to immune checkpoint inhibitors in OCCC. In this review, we highlight recent update and progress in OCCC from both the genomic and immunologic points of view, addressing the future candidate therapeutic options.

Clear cell carcinomas of the ovary and kidney: clarity through genomics

Clear cell ovarian carcinoma (CCOC) and clear cell renal cell carcinoma (ccRCC) both feature clear cytoplasm, owing to the accumulation of cytoplasmic glycogen. Genomic studies have demonstrated several mutational similarities between these two diseases, including frequent alterations in the chromatin remodelling SWI-SNF and cellular proliferation phosphoinositide 3-kinase-mammalian target of rapamycin pathways, as well as a shared hypoxia-like mRNA expression signature. Although many targeted treatment options have been approved for advanced-stage ccRCC, CCOC patients are still treated with conventional platinum and taxane chemotherapy, to which they are resistant. To determine the extent of similarity between these malignancies, we performed unsupervised clustering of mRNA expression data from these cancers. This review highlights the similarities and differences between these two clear cell carcinomas to facilitate knowledge translation within future research efforts. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Metabolic alterations caused by HNF1β expression in ovarian clear cell carcinoma contribute to cell survival

HNF1β is expressed exclusively in ovarian clear cell carcinoma (OCCC) and not in other ovarian cancers, regarded as a hallmark of this tumor. This implies its central role in the unique character of OCCC, including resistance to chemotherapy, but its exact role and influence in cancer biology or the molecular bases of its function are largely unknown. Using comprehensive metabolome analysis of HNF1β_shRNA-stable cell lines, we show here that HNF1β drastically alters intracellular metabolism, especially in direction to enhance aerobic glycolysis, so called the “Warburg effect”. The consequence of the metabolic change contributed cell survival under stresses such as hypoxia and chemo-reagent, only when sufficient glucose supply was available. Augmented cell survival was based on the reduced ROS activity derived from metabolic alteration such as shift from oxidative phosphorylation to glycolysis and increased intracellular anti-oxidant, glutathione (GSH). One of the cystine transporters, rBAT is likely to play a major role in this GSH increase. These data suggest that HNF1β, possibly induced by stressful microenvironment in the endometriotic cyst, confers survival advantage to the epithelial cells, which leads to the occurrence of OCCC, a chemo-resistant phenotype of ovarian cancer.

Crosstalk between PI3K and Ras pathways via protein phosphatase 2A in human ovarian clear cell carcinoma

Hypoxia-inducible factor-1 (HIF-1) is one of the most promising pharmacological targets for all types of cancer, including ovarian cancer. Ovarian clear cell carcinoma (OCCC) has poor prognosis because of its insensitivity to chemotherapy. To elucidate the characteristics of this troublesome cancer, we examined HIF-1α expression under normoxia or hypoxia in various ovarian cancer cell lines. HIF-1α was highly expressed under normoxia only in RMG-1, an OCCC cell line. To examine whether HIF-1 is involved in the tumorigenesis of RMG-1 cells, we established HIF-1α-silenced cells, RMG-1HKD. The proliferation rate of RMG-1HKD cells was faster than that of RMG-1 cells. Furthermore, the activity of MEK/ERK in the Ras pathway increased in RMG-1HKD cells, whereas that of mTOR in the PI3K pathway did not change. Activation of the Ras pathway was attributable to the increase in phosphorylated MEK via PP2A inactivation. To confirm the crosstalk between the PI3K and Ras pathways in vivo, RMG-1 or RMG-1HKD cells were transplanted into the skin of nude mice with rapamycin (an inhibitor of mTOR), PD98059 (an inhibitor of MEK), or both. RMG-1HKD cells showed higher sensitivity to PD98059 than that observed in RMD-1 cells, whereas the combination therapy resulted in synergistic inhibition of both cells. These findings suggest that inhibition of HIF-1, a downstream target of mTOR in the PI3K pathway, activates the Ras pathway on account of the increase in MEK phosphorylation via PP2A inactivation, and the crosstalk between the 2 pathways could be applied in the combination therapy for HIF-1-overexpressing cancers such as OCCC.

Ovarian clear cell carcinoma meets metabolism; HNF-1β confers survival benefits through the Warburg effect and ROS reduction

Ovarian clear cell carcinoma (OCCC) constitutes one of the subtypes of ovarian cancers, but it has unique clinical, histological and biological characteristics, one of which is chemo-resistance. It is also known to develop from endometriotic cyst, a benign ovarian tumor, at relatively high frequency. Recently, it is becoming well known that most of OCCCs express HNF1β, a transcription factor, which is closely associated with the development of liver, pancreas and kidney, as well as occurrence of familial forms of type 2 diabetes. Expression of HNF1β is now regarded as a hallmark of this tumor. Nevertheless, exact biological function of this gene in OCCC has not been clarified. We have shown in previous studies that microenvironment in endometriotic cysts contains severe oxidative stress and OCCC develops under such stressful environment as stress-resistant tumor, which may lead to chemo-resistance. We also showed that increased expression of HNF1β facilitates glucose uptake and glycolysis, which is known as Warburg effect. In the previous issue of this journal, by using comprehensive metabolome analysis, we report that HNF1β actually reduces and protects themselves from internal oxidative stress by dramatically changing cellular metabolism. In this article, we review the relevance and significance of cancer-specific metabolism and how they are associated with biological characteristics of OCCC via expression of HNF1β, along with future clinical implications of targeting cancer-specific metabolism.

Antiangiogenic agents in gynecological cancer: State of art and perspectives of clinical research

Vascular endothelial growth factor [VEGF] pathway, which plays a key role in angiogenesis, may be blocked by either extracellular interference with VEGF itself (bevacizumab [BEV] or aflibercept), or intracytoplasmic inhibition of VEGF receptor (pazopanib, nintedanib, cediranid, sunitinib and sorafenib). An alternative approach is represented by trebananib, a fusion protein that prevents the interaction of angiopoietin [Ang]-1 and Ang-2 with Tie2 receptor on vascular endothelium. The combination of antiangiogenic agents, especially BEV, and chemotherapy is a rational therapeutic option for primary or recurrent ovarian carcinoma. However, it will be difficult to accept that it represents the new standard treatment, until biological characterization of ovarian carcinoma has not identified subsets of tumors with different responsiveness to BEV. Anti-angiogenesis is an interesting target also for recurrent cervical or endometrial cancer, but nowadays the use of anti-angiogenic agents in these malignancies should be reserved to patients enrolled in clinical trials.

Epigenetic determinants of ovarian clear cell carcinoma biology

Targeted approaches have revealed frequent epigenetic alterations in ovarian cancer, but the scope and relation of these changes to histologic subtype of disease is unclear. Genome-wide methylation and expression data for 14 clear cell carcinoma (CCC), 32 non-CCC and four corresponding normal cell lines were generated to determine how methylation profiles differ between cells of different histological derivations of ovarian cancer. Consensus clustering showed that CCC is epigenetically distinct. Inverse relationships between expression and methylation in CCC were identified, suggesting functional regulation by methylation, and included 22 hypomethylated (UM) genes and 276 hypermethylated (HM) genes. Categorical and pathway analyses indicated that the CCC-specific UM genes were involved in response to stress and many contain hepatocyte nuclear factor (HNF) 1-binding sites, while the CCC-specific HM genes included members of the estrogen receptor alpha (ERalpha) network and genes involved in tumor development. We independently validated the methylation status of 17 of these pathway-specific genes, and confirmed increased expression of HNF1 network genes and repression of ERalpha pathway genes in CCC cell lines and primary cancer tissues relative to non-CCC specimens. Treatment of three CCC cell lines with the demethylating agent Decitabine significantly induced expression for all five genes analyzed. Coordinate changes in pathway expression were confirmed using two primary ovarian cancer datasets (p < 0.0001 for both). Our results suggest that methylation regulates specific pathways and biological functions in CCC, with hypomethylation influencing the characteristic biology of the disease while hypermethylation contributes to the carcinogenic process.

Clear cell carcinoma of ovary and uterus

Clear cell carcinomas of the female genital tract are rare tumours with a fearsome reputation for having poor responses to conventional platinum-based chemotherapy and poor prognosis. However, it is now clear that early-stage ovarian clear cell carcinoma has an excellent prognosis and may not require any adjuvant therapy. In addition, radiotherapy may also have a key role to play in adjuvant management of clear cell tumours. Identification of patients who truly do not need adjuvant chemotherapy is important. The past 3 years has seen a significant improvement in our understanding of clear cell carcinoma biology-in particular, the role of mutations in the chromatin remodelling gene ARID1A as key drivers that are common to clear cell carcinomas of ovarian and endometrial origin. Moreover, gynaecological clear cell carcinomas appear to share many features with renal clear cell tumours, suggesting a common pathogenesis. This raises the possibility of clinical trials that include patients with clear cell tumours from different organs of origin. Dissecting the role of disordered chromatin organisation in clear cell carcinoma pathogenesis is a key priority. Finally, the role of endometriosis and the attendant chronic inflammation are recognised. The inflammatory cytokine interleukin-6 appears to play a key role in clear cell carcinoma biology and is an excellent potential therapeutic target.

Recent concepts of ovarian carcinogenesis: type I and type II

Type I ovarian tumors, where precursor lesions in the ovary have clearly been described, include endometrioid, clear cell, mucinous, low grade serous, and transitional cell carcinomas, while type II tumors, where such lesions have not been described clearly and tumors may develop de novo from the tubal and/or ovarian surface epithelium, comprise high grade serous carcinomas, undifferentiated carcinomas, and carcinosarcomas. The carcinogenesis of endometrioid and clear cell carcinoma (CCC) arising from endometriotic cysts is significantly influenced by the free iron concentration, which is associated with cancer development through the induction of persistent oxidative stress. A subset of mucinous carcinomas develop in association with ovarian teratomas; however, the majority of these tumors do not harbor any teratomatous component. Other theories of their origin include mucinous metaplasia of surface epithelial inclusions, endometriosis, and Brenner tumors. Low grade serous carcinomas are thought to evolve in a stepwise fashion from benign serous cystadenoma to a serous borderline tumor (SBT). With regard to high grade serous carcinoma, the serous tubal intraepithelial carcinomas (STICs) of the junction of the fallopian tube epithelium with the mesothelium of the tubal serosa, termed the “tubal peritoneal junction” (TPJ), undergo malignant transformation due to their location, and metastasize to the nearby ovary and surrounding pelvic peritoneum. Other theories of their origin include the ovarian hilum cells.

Two cases of recurrent ovarian clear cell carcinoma treated with sorafenib

Sorafenib is an oral multikinase inhibitor targeting Raf and other kinases. The anti-tumor effect of sorafenib is thought to be mediated through its inhibition of the RAS-Raf-Erk pathway, as well as its inhibition of VEGFR and PDGFR. Sorafenib has been effective at treating patients with renal cell carcinoma (RCC). Ovarian clear cell carcinoma (OCCC) is a chemoresistant subtype of ovarian cancer. OCCC is represented by cells with clear cytoplasm that resemble those observed in RCC. Using a microarray database, the gene expression profile of OCCC was similar to that of RCC. The effects of sorafenib against human OCCC are unknown. Therefore, we used sorafenib to treat two patients with recurrent chemoresistant OCCC, and observed good effect in both of them without severe side effects. We believe that sorafenib is an effective agent against OCCC. Given the chemoresistant nature of this tumor, this drug appears to be very valuable.

The potential of sunitinib as a therapy in ovarian cancer

INTRODUCTION

Sunitinib malate (SU11248; Sutent®; Pfizer, Inc., New York) is a multi-kinase inhibitor currently approved for use in advanced renal cell carcinoma (RCC), imatinib-resistant/-intolerant gastrointestinal stromal tumours and progressive, well-differentiated pancreatic neuroendocrine tumours in patients with unresectable, locally advanced or metastatic disease.

AREAS COVERED

This article describes the mechanism of action and of the pharmacokinetics of sunitinib; further, it summarizes Phase I and II trials on the clinical efficacy, tolerability and safety of this agent in the setting of ovarian cancer (OC) treatment.

EXPERT OPINION

On the basis of the current literature, sunitinib has shown modest antitumour activity and acceptable toxicity. Studies investigating the impact of horizontal and vertical combinations should represent a priority of future research. Although clinical Phase II trials on the use of sunitinib in the treatment of OC demonstrated an acceptable profile of AEs, a greater comprehension of the toxicity of this compound is recommended.

Hepatocyte nuclear factor-1β (HNF-1β) promotes glucose uptake and glycolytic activity in ovarian clear cell carcinoma

Ovarian clear cell carcinoma (OCCC) is a morphologically and biologically distinct subtype of ovarian carcinomas that often arises in ovarian endometriosis. We previously reported that a unique carcinogenic environment, especially iron-induced oxidative stress in endometriotic cysts may promote development of OCCC. We also identified a gene expression profile characteristic of OCCC (the "OCCC signature"). This 320-gene OCCC signature is enriched in genes associated with stress response and sugar metabolism. However, the biological implication of this profile is unclear. In this study, we have focused on the biological role of the HNF-1β gene within the OCCC signature, which was previously shown to be overexpressed in OCCC. Suppression of HNF-1β in the HNF-1β-overexpressing human ovarian cancer cell line RMG2 using short hairpin RNA resulted in a significant increase in proliferation. It also facilitated glucose uptake, glycolytic activity, and lactate secretion along with increased expression of the glucose transporter-1 (GLUT-1) gene and several key enzymes in the glycolytic process. Conversely, forced expression of HNF-1β in the serous ovarian cancer cell line, Hey, resulted in slowed cellular growth and repressed glycolytic activity. These data suggest that HNF-1β represses cell growth, and at the same time, it promotes aerobic glycolysis which is known as the "Warburg effect." As the Warburg effect is regarded as a characteristic metabolic process in cancer which may contribute to cell survival under hypoxic conditions or in a stressful environment, overexpression of HNF-1β may play an inevitable role in the occurrence of OCCC in stressful environment.

Angiogenesis-related pathways in the pathogenesis of ovarian cancer

Ovarian Cancer represents the most fatal type of gynecological malignancies. A number of processes are involved in the pathogenesis of ovarian cancer, especially within the tumor microenvironment. Angiogenesis represents a hallmark phenomenon in cancer, and it is responsible for tumor spread and metastasis in ovarian cancer, among other tumor types, as it leads to new blood vessel formation. In recent years angiogenesis has been given considerable attention in order to identify targets for developing effective anti-tumor therapies. Growth factors have been identified to play key roles in driving angiogenesis and, thus, the formation of new blood vessels that assist in "feeding" cancer. Such molecules include the vascular endothelial growth factor (VEGF), the platelet derived growth factor (PDGF), the fibroblast growth factor (FGF), and the angiopoietin/Tie2 receptor complex. These proteins are key players in complex molecular pathways within the tumor cell and they have been in the spotlight of the development of anti-angiogenic molecules that may act as stand-alone therapeutics, or in concert with standard treatment regimes such as chemotherapy. The pathways involved in angiogenesis and molecules that have been developed in order to combat angiogenesis are described in this paper.

A Case of Stage III c Ovarian Clear Cell Carcinoma: The Role for Predictive Biomarkers and Targeted Therapies

Ovarian cancer treatment presently does not reflect molecular differences in histologic subtype. Ovarian clear cell carcinoma (OCCC) exhibits several differences in terms of molecular pathogenesis and tumor behavior from the more common, chemosensitive, serous carcinomas, which makes OCCC a candidate for targeted therapies. A 53-year-old Japanese woman was diagnosed with stage IIIc ovarian clear cell adenocarcinoma with marked chemoresistance to conventional regimens. She demonstrated a partial response to a multikinase inhibitor. The tumor was resistant to PI3K/mTOR pathway inhibitors despite harboring a PIK3CA mutation. The present case suggests a role for targeted therapies in the treatment of OCCC and a need for the identification of biomarkers that will predict response to targeted therapies.

Recent alcohol consumption and risk of incident ovarian carcinoma: a pooled analysis of 5,342 cases and 10,358 controls from the Ovarian Cancer Association Consortium

BACKGROUND

Studies evaluating the association between alcohol intake and ovarian carcinoma (OC) are inconsistent. Because OC and ovarian borderline tumor histologic types differ genetically, molecularly and clinically, large numbers are needed to estimate risk associations.

METHODS

We pooled data from 12 case-control studies in the Ovarian Cancer Association Consortium comprising 5,342 OC cases, 1,455 borderline tumors and 10,358 controls with quantitative information on recent alcohol intake to estimate odds ratios (OR) and 95% confidence intervals (CI) according to frequencies of average daily intakes of beer, wine, liquor and total alcohol.

RESULTS

Total alcohol intake was not associated with all OC: consumption of >3 drinks per day compared to none, OR=0.92, 95% CI=0.76-1.10, P trend=0.27. Among beverage types, a statistically non-significant decreased risk was observed among women who consumed >8 oz/d of wine compared to none (OR=0.83, 95% CI=0.68-1.01, P trend=0.08). This association was more apparent among women with clear cell OC (OR, 0.43; 95% CI, 0.22-0.83; P trend=0.02), although based on only 10 cases and not statistically different from the other histologic types (P value for statistical heterogeneity between histologic types = 0.09). Statistical heterogeneity of the alcohol- and wine-OC associations was seen among three European studies, but not among eight North American studies. No statistically significant associations were observed in separate analyses evaluating risk with borderline tumors of serous or mucinous histology. Smoking status did not significantly modify any of the associations.

CONCLUSIONS

We found no evidence that recent moderate alcohol drinking is associated with increased risk for overall OC, or that variation in risk is associated strongly with specific histologic types. Understanding modifiable causes of these elusive and deadly cancers remains a priority for the research community.

Significance of vascular endothelial growth factor in growth and peritoneal dissemination of ovarian cancer

Vascular endothelial growth factor (VEGF) is a key regulator of angiogenesis which drives endothelial cell survival, proliferation, and migration while increasing vascular permeability. Playing an important role in the physiology of normal ovaries, VEGF has also been implicated in the pathogenesis of ovarian cancer. Essentially by promoting tumor angiogenesis and enhancing vascular permeability, VEGF contributes to the development of peritoneal carcinomatosis associated with malignant ascites formation, the characteristic feature of advanced ovarian cancer at diagnosis. In both experimental and clinical studies, VEGF levels have been inversely correlated with survival. Moreover, VEGF inhibition has been shown to inhibit tumor growth and ascites production and to suppress tumor invasion and metastasis. These findings have laid the basis for the clinical evaluation of agents targeting VEGF signaling pathway in patients with ovarian cancer. In this review, we will focus on VEGF involvement in the pathophysiology of ovarian cancer and its contribution to the disease progression and dissemination.

Utility of vascular endothelial growth factor inhibitors in the treatment of ovarian cancer: from concept to application

Despite recent advances in the management of ovarian cancer, it remains the most lethal gynecologic malignancy. Vascular endothelial growth factor (VEGF) has been shown to play a pivotal role in the progression of ovarian cancer leading to the eventual development of malignant ascites. On this basis, agents rendering VEGF ineffective by neutralizing VEGF (bevacizumab), blocking its receptors (aflibercept), or interfering with the postreceptor signaling pathways (sunitinib) provide us with the rational treatment options. These agents are generally used in combination with the standard chemotherapeutic drugs. Here, we discuss the basis of and the logic behind the use of these agents in the treatment of epithelial ovarian cancer, as well as their evaluation in different preclinical and clinical studies.

Ovarian clear cell carcinoma as a stress-responsive cancer: influence of the microenvironment on the carcinogenesis and cancer phenotype

Although it is well known that ovarian endometriosis occasionally gives rise to ovarian cancers with specific histology such as endometrioid and clear cell carcinomas, its etiology is not fully understood. We have shown that a stressful microenvironment within the endometriotic cyst may lead to cancer development by inducing unique gene expressions, which potentially serves as a molecular marker for treatment modality. In this review, by referring to other articles in this field, we explore how the carcinogenic microenvironment affects the phenotype and gene expression of a cancer, and how we can develop new treatment based on this concept.