Ovarian cancer immunotherapy: opportunities, progresses and challenges

CD4+CCR8+ Tregs in ovarian cancer: a potential effector Tregs for immune regulation

BACKGROUND

Tregs are key drivers of immunosuppression in solid tumors. As an important chemokine receptor on Tregs, the regulatory effect of CCR8 on tumor immunity has received more and more attention. However, the current research on CCR8 in the immune microenvironment of ovarian cancer has not been clear.

METHODS

Bioinformatics analysis was used to compare the transcriptome differences between CD4+ T cells in the peripheral circulation and infiltrated in ovarian tumor tissues. RT-PCR was used to detect the expression levels of chemokine receptor-related differential genes on CD4+ T cells in peripheral blood and ovarian tumor tissues. Multiparameter flow cytometry was used to detect the proportion and phenotypic characteristics of CD4+CCR8+ Tregs and CD4+CCR8- Tregs in different sample types. The expression level of CCR8 ligands was detected at multiple levels. To explore the important role of CCR8-CCL1 and CCR8-CCL18 axis in the migration and invasion of CD4+CCR8+ Tregs into ovarian tumor tissues by establishing a chemotaxis system in vitro.

RESULTS

In this study, significantly different gene expression profiles were found between peripheral circulating CD4+ T cells and infiltrating CD4+ T cells in ovarian tumor tissues, in which chemokine-chemokine receptor signaling pathway was significantly enriched in all three groups of differential genes. The expression level of CCR8 in infiltrating CD4+ T cells of ovarian cancer tissue was significantly higher than that in peripheral blood of healthy controls and ovarian cancer patients, and high expression of CCR8 was significantly correlated with advanced tumor stage and poor differentiation. CD4+CCR8+ Tregs are the main type of infiltrating CD4+ Tregs in ovarian tumor tissues, which have stronger immunosuppressive phenotypes, secrete more inhibitory cytokines and have stronger proliferation ability. The ligands CCL1 and CCL18 corresponding to CCR8 were significantly overexpressed in ovarian tumor tissues, and the CCR8-CCL1 and CCR8-CCL18 axis played a key role in the migration and infiltration of CD4+CCR8+ Tregs into ovarian tumor tissues.

CONCLUSIONS

The results of this study may help to understand the phenotypic characteristics and recruitment process of Tregs in the tumor, and provide new ideas for improving the immunosuppressive status of the ovarian cancer microenvironment.

Cancer Immunoediting: Elimination, Equilibrium, and Immune Escape in Solid Tumors

Emphasizing the dynamic processes between cancer and host immune system, the initially discovered concept of cancer immunosurveillance has been replaced by the current concept of cancer immunoediting consisting of three phases: elimination, equilibrium, and escape. Solid tumors composed of both cancer and host stromal cells are an example how the three phases of cancer immunoediting functionally evolve and how tumor shaped by the host immune system gets finally resistant phenotype. The elimination, equilibrium, and escape have been described in this chapter in details, including the role of immune surveillance, cancer dormancy, disruption of the antigen-presenting machinery, tumor-infiltrating immune cells, resistance to apoptosis, as well as the function of tumor stroma, microvesicles, exosomes, and inflammation.

Enhancing delivery of small molecule and cell-based therapies for ovarian cancer using advanced delivery strategies

Ovarian cancer is the most lethal gynecological malignancy with a global five-year survival rate of 30-50%. First-line treatment involves cytoreductive surgery and administration of platinum-based small molecules and paclitaxel. These therapies were traditionally administered via intravenous infusion, although intraperitoneal delivery has also been investigated. Initial clinical trials of intraperitoneal administration for ovarian cancer indicated significant improvements in overall survival compared to intravenous delivery, but this result is not consistent across all studies performed. Recently cell-based immunotherapy has been of interest for ovarian cancer. Direct intraperitoneal delivery of cell-based immunotherapies might prompt local immunoregulatory mechanisms to act synergistically with the delivered immunotherapy. Based on this theory, pre-clinical in vivo studies have delivered these cell-based immunotherapies via the intraperitoneal route, with promising results. However, successful intraperitoneal delivery of cell-based immunotherapy and clinical adoption of this technique will depend on overcoming challenges of intraperitoneal delivery and finding the optimal combinations of dose, therapeutic and delivery route. We review the potential advantages and disadvantages of intraperitoneal delivery of cell-based immunotherapy for ovarian cancer and the pre-clinical and clinical work performed so far. Potential advanced delivery strategies, which might improve the efficacy and adoption of intraperitoneal delivery of therapy for ovarian cancer, are also outlined.

microRNA-1271-5p/TIAM1 suppresses the progression of ovarian cancer through inactivating Notch signaling pathway

Objective

Ovarian cancer (OC) has been regarded as the most malignant gynecological neoplasm and often confers grave outcomes owing to the frequent metastasis and high recurrence. A previous study has demonstrated that miR-1271-5p is implicated in OC progression, however, the possible mechanism of it remains unknown. The purpose of this investigation was to explore how miR-1271-5p regulates the progression of OC.

Methods

Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases were employed to analyze the differentially expressed miRNAs or genes as well as their corresponding prognostic values. miR-1271-5p expression in OC cells was examined by qRT-PCR. Cell counting kit 8 (CCK-8), colony formation, and transwell tests were conducted to evaluate the proliferation, migration and invasion potentials. Bioinformatics prediction and luciferase activity analysis were utilized to predict and verify the target gene of miR-1271-5p. Western blot assay was carried out to measure protein expression.

Results

miR-1271-5p was significantly decreased in OC and its down-regulation was associated with the grave outcome of OC patients. Upregulation of miR-1271-5p inhibited cell viability, but miR-1271-5p knockdown promoted the proliferation of OC cells. TIAM1 was a direct target gene of miR-1271-5p and expressed in OC tissues at higher level. High expression of TIAM1 induced the poorer prognosis of patients with OC. Further functional analyses showed that the suppressive role of miR-1271-5p on OC cell malignant behaviors was overturned by the upregulation of TIAM1. The protein levels of Cyclin D1, HES1, NOTCH and NUMB were remarkably changed due to the abnormal expression of miR-1271-5p and TIAM1.

Conclusion

To sum up, miR-1271-5p inhibits proliferation, invasion and migration of OC cells by directly repressing TIAM1 to inactivate the Notch signaling pathway, which provides an alternative therapeutic candidate for the advancement of OC treatment.

MiR-217 Inhibits M2-Like Macrophage Polarization by Suppressing Secretion of Interleukin-6 in Ovarian Cancer

Ovarian cancer is one of the most deadly cancers with rapid proliferation and poor prognosis among patients. Therapies focusing on regulation of tumor immunity and microenvironments are developing. MiR-217 was dysregulated in cancer progress and plays important roles in tumorigenesis and metastasis. However, the role of miR-217 in regulation of macrophage polarization and its underlying molecular mechanism remain unclear. The expression of miR-217 in ovarian cancerous tissues and cell lines were assessed by qRT-PCR. And we detected the staining of CD86 and CD206 via flow-cytometry and the levels of Arg-1 and CCR2 by western-blot in order to evaluate M2 macrophage polarization. The targeting regulation of miR-217 on pro-inflammatory factor IL-6 was assessed by dual-luciferase reporter assay and western-blot. ELISA assay was used to evaluate the secretion of IL-6 and IL-10 of cells. MiR-217 was found to be downregulated in ovarian cancerous tissues and cell lines. This downregulation correlated with an increased expression of the IL-6, Arg-1, CCR2, and CD206 gene. The overexpression of miR-217 in SKOV3 cells can inhibit the polarization of macrophages towards an M2-like phenotype. We also found that IL-6 was validated to induce M2 macrophage polarization and its secretion in SKOV-3 cells was inhibited by miR-217 directly. Moreover, we revealed that miR-217 suppressed M2 macrophage polarization partly thought JAK/STAT3 signal pathway. Taken together, these findings indicate that miR-217 inhibits tumor-induced M2 macrophage polarization through targeting of IL-6 and regulation JAK3/STAT3 signaling pathway, which may provide a potential therapeutic target for treating ovarian cancer.

Kallikrein-related peptidases protein expression in lymphoid tissues suggests potential implications in immune response

OBJECTIVES

Kallikrein-related peptidases (KLKs) are a subgroup of 15 secreted chymotrypsin- and trypsin-like serine proteases that have been reported to possess novel functions in innate immunity and inflammation. Since the potential role of KLKs in immunity has not been studied in detail at the protein level, we examined the expression pattern of 12 members of the KLK family in immune-related tissues.

DESIGN & METHODS

Protein expression in tissue extracts was evaluated using immunoassays (ELISA). Immunohistochemistry (IHC) was performed on representative sections of tonsil and lymph nodes to determine the cellular localization of the KLK family members.

RESULTS

ELISA profiling of KLK3-KLK15 (except KLK12) revealed higher protein levels in the tonsil, compared to the lymph nodes and spleen. Relatively high protein levels in the tonsil were observed for KLK7, KLK9, KLK10 and KLK13. Expression of these KLKs was significantly lower in lymph nodes and spleen. IHC analysis in tonsil unveiled that KLK9 and KLK10 were differentially expressed in lymphoid cells. KLK9 was strongly expressed in the germinal center of lymphoid follicles where activated B-cells reside, whereas KLK10 was expressed in the follicular dendritic cells (FDCs) that are vital for maintaining the cycle of B cell maturation.

CONCLUSION

Overall, our study revealed the possible implications of KLK expression and regulation in the immune cells of lymphoid tissues.

Modulation of double-stranded RNA pattern recognition receptor signaling in ovarian cancer cells promotes inflammatory queues

Inflammation and cancer are inter-related, and both pro- and anti-tumorigenic effects are possible in different contexts, highlighting the importance of characterizing specific inflammatory pathways in distinct tumor types. Malignant cells and non-cancerous cells such as fibroblasts, infiltrating leukocytes (i.e., dendritic cells [DC], macrophages, or lymphocytes) and endothelial cells, in combination with the extracellular matrix, constitute the tumor microenvironment (TME). In the last decades, the role of the TME in cancer progression has gained increased attention and efforts directed at abrogating its deleterious effects on anti-cancer therapies have been ongoing. In this context, we investigated the potential of mouse and human ovarian cancer cells to produce inflammatory factors in response to pathogen recognition receptor (PRR) signaling, which might help to shape the biology of the TME. We determined that mouse ovarian tumors generate chemokines that are able to interact with receptors harbored by tumor-associated DCs. We also found that dsRNA triggers significant pro-inflammatory cytokine up-regulation in both human and mouse ovarian tumor cell lines, and that several PRR can simultaneously contribute to the stimulated inflammatory response displayed by these cells. Thus, dsRNA-activated PRRs may not only constitute potentially relevant drug targets for therapies aiming to prevent inflammation associated with leukocyte recruitment, or as co-adjuvants of therapeutic treatments, but also might have a role in development of nascent tumors, for example via activation of cancer cells by microbial molecules associated to pathogens, or with those appearing in circulation due to dysbiosis.

MicroRNA-508 suppresses epithelial-mesenchymal transition, migration, and invasion of ovarian cancer cells through the MAPK1/ERK signaling pathway

Ovarian cancer (OC) is the sixth most common cancer in women worldwide. Despite advances in detection and therapies, it still represents the most lethal gynecologic malignancy in the industrialized countries. Unfortunately, the molecular events that lead to the development of this highly aggressive disease remain largely unknown. The study explored the ability of microRNA-508 (miR-508) to influence proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) in OC cells. We quantified the level of miR-508 cancer tissues with corresponding adjacent normal tissues collected from 84 patients with OC. Human OC cells SKOV3 and A2780 were treated with negative control (NC), miR-508 mimics, miR-508 inhibitors, and miR-508 inhibitors + a specific MAPK/ERK kinase inhibitor (PD98059) to validate the interaction between miR-508 and MAPK/ERK signaling. The miR-508 expression level was lower while MAPK1 and ERK expression levels were higher in the cancer tissues than in the adjacent normal tissues. Dual-luciferase reporter assay indicated MAPK1 as a target gene of miR-508. The miR-508 mimics reduced the expression of MAPK1, p-MAPK1, ERK, p-ERK and Vimentin, inhibited cell proliferation, migration and invasion, and increased the expression of E-cadherin, while the miR-508 inhibitors resulted in an opposed trend in OC cells. The effects of miR-508 inhibitors on OC cells were lost when the MAPK1/ERK signaling pathway was inhibited by PD98059. Collectively, our data indicate that miR-508 plays a tumor suppressor role in the development and progression of OC and may be a novel therapeutic target against OC.

Improving cancer detection through combinations of cancer and immune biomarkers: a modelling approach

Background

Early cancer diagnosis is one of the most important challenges of cancer research, since in many cancers it can lead to cure for patients with early stage diseases. For epithelial ovarian cancer (which is the leading cause of death among gynaecologic malignancies) the classical detection approach is based on measurements of CA-125 biomarker. However, the poor sensitivity and specificity of this biomarker impacts the detection of early-stage cancers.

Methods

Here we use a computational approach to investigate the effect of combining multiple biomarkers for ovarian cancer (e.g., CA-125 and IL-7), to improve early cancer detection.

Results

We show that this combined biomarkers approach could lead indeed to earlier cancer detection. However, the immune response (which influences the level of secreted IL-7 biomarker) plays an important role in improving and/or delaying cancer detection. Moreover, the detection level of IL-7 immune biomarker could be in a range that would not allow to distinguish between a healthy state and a cancerous state. In this case, the construction of solution diagrams in the space generated by the IL-7 and CA-125 biomarkers could allow us predict the long-term evolution of cancer biomarkers, thus allowing us to make predictions on cancer detection times.

Conclusions

Combining cancer and immune biomarkers could improve cancer detection times, and any predictions that could be made (at least through the use of CA-125/IL-7 biomarkers) are patient specific.

The immunopeptidomic landscape of ovarian carcinomas

Immunotherapies, particularly checkpoint inhibitors, have set off a revolution in cancer therapy by releasing the power of the immune system. However, only little is known about the antigens that are essentially presented on cancer cells, capable of exposing them to immune cells. Large-scale HLA ligandome analysis has enabled us to exhaustively characterize the immunopeptidomic landscape of epithelial ovarian cancers (EOCs). Additional comparative profiling with the immunopeptidome of a variety of benign sources has unveiled a multitude of ovarian cancer antigens (MUC16, MSLN, LGALS1, IDO1, KLK10) to be presented by HLA class I and class II molecules exclusively on ovarian cancer cells. Most strikingly, ligands derived from mucin 16 and mesothelin, a molecular axis of prognostic importance in EOC, are prominent in a majority of patients. Differential gene-expression analysis has allowed us to confirm the relevance of these targets for EOC and further provided important insights into the relationship between gene transcript levels and HLA ligand presentation.

Potential role of radiation therapy in augmenting the activity of immunotherapy for gynecologic cancers

Immune checkpoint inhibitors have become an area of intense interest in oncology and are actively being studied in a variety of cancer types with a wide range of success. In vitro data suggest mechanisms by which radiation can activate the immune system, and ongoing studies are exploring the potential interaction of checkpoint inhibitors with radiotherapy in both preclinical and clinical settings. Gynecologic malignancies are a heterogeneous group of tumors with varying prognoses, intrinsic immunogenicity, and potential for response to immune-based therapies. In this review, we focus on the rationale for immunotherapy and opportunities for augmentation by photon radiotherapy in cancers of the cervix, endometrium, and ovary.

Tissue and plasma levels of galectins in patients with high grade serous ovarian carcinoma as new predictive biomarkers

Galectins are moving closer to center stage in detecting glycosylation aberration in cancer cells. Here, we have investigated the expression of galectins in ovarian cancer (OC) and examined their potential as biomarkers in tissues and blood plasma samples of high grade serous ovarian carcinoma (HGSC) patients. In tissues, we found that increased protein expression of stromal gal-1 and epithelial gal-8/9 was associated with a poor response to treatment of HGSC patients. Gal-8/9 were both independent predictors of chemoresistance and overall survival (OS), respectively. This galectin signature increased the predictive value of the cancer antigen 125 (CA125) on 5-year disease-free survival (DFS), post-chemotherapy treatment and 5-year OS. In CA125^LOW patients, epithelial gal-9 was associated with a lower 5-year OS while stromal gal-1 and epithelial gal-8 were both associated with a lower 5-year DFS. Such negative predictive value of gal-8 and gal-9 was also found using plasma samples. In both cases, high plasma levels of gal-8 and gal-9 was associated with a lower OS and DFS. Overall, these data suggest that galectins may be promising biomarkers to identify subgroups of HGSC patients with poorer prognosis. Our study also contributes to better define the heterogeneity of the disease.

Relationship between HER2 and JAK/STAT-SOCS3 signaling pathway and clinicopathological features and prognosis of ovarian cancer

OBJECTIVE

The study aims to explore the relationship between expressions of HER2 and JAK/STAT3-SOCS3 signaling pathway and clinicopathological features and prognosis of ovarian cancer (OC).

METHODS

A total of 136 OC patients were collected. Immunohistochemistry was applied to measure the expressions of STAT3, p-STAT3, SOCS3, HER2 and p-HER2 in the tumor tissues and adjacent normal tissues. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the mRNA expressions of HER2, SOCS3 and STAT3 and western blotting was applied for protein expressions of HER2, p-HER2, SOCS3, STAT3 and p-STAT3 in the tumor tissues and adjacent normal tissues. Flow cytometry was used for the cell apoptosis in the blank, afatinib (A), ruxolitinib (R) and afatinib + ruxolitinib (A + R) groups. Follow-up was performed to explore relationship of HER2, SOCS3, and STAT3 expressions with survival time of OC patients.

RESULTS

HER2, p-HER2, STAT3, and p-STAT3 expressions were higher while SOCS3 expression was lower in the tumor tissues. The positive expressions of STAT3, HER2, p-HER2 and p-STAT3 were lower while the positive expression of SOCS3 was higher in the adjacent normal tissues. The expressions of HER2, SOCS3, and p-STAT3 were associated with clinical stage and lymph node metastasis (LNM), and STAT3 expression has correlation with histological grade and LNM. The mRNA and protein expressions of HER2, STAT3 and p-STAT3 in the tumor tissues were higher than those in the adjacent normal tissues, but SOCS3 expression was significantly decreased. The positive expressions of HER2, p-HER2 and STAT3, the negative expression of SOCS3 and pathological stages were important risk factors for the prognosis of patients with OC.

CONCLUSION

Our study showed that the expressions of HER2, STAT3, and SOCS3 are associated with the progression of OC, and higher expressions of HER2 and STAT3 and lower expression of SOCS3 predict poor prognosis of OC.

Interleukin-10 and prostaglandin E2 have complementary but distinct suppressive effects on Toll-like receptor-mediated dendritic cell activation in ovarian carcinoma

Dendritic cells (DC) have the potential to instigate a tumour-specific immune response, but their ability to prime naïve lymphocytes depends on their activation status. Thus, for tumour immunotherapy to be effective, the provision of appropriate DC activation stimuli such as Toll-like receptor (TLR) agonists is crucial in order to overcome immunosuppression associated with the tumour microenvironment. To address this, we investigated how ovarian carcinoma (OC)-associated ascites impedes activation of DC by TLR agonists. Our results show that ascites reduces the TLR-mediated up-regulation of CD86 and partially inhibits the production of the pro-inflammatory cytokines interleukin 6 (IL-6), IL-12 and tumour necrosis factor α (TNFα) in monocyte-derived DC from healthy controls. We further observe an impaired T cell stimulatory capacity of DC upon activation with TLR agonists in the presence of ascites, indicating that their functionality is affected by the immunosuppressive factors. We identify IL-10 and prostaglandin E2 (PGE₂) as the pivotal immunosuppressive components in OC-associated ascites compromising TLR-mediated DC activation. Interestingly, IL-10 is present in both ascites from patients with malignant OC and in peritoneal fluid from patients with benign ovarian conditions and both fluids have similar ability to reduce TLR-mediated DC activation. However, depletion of IL-10 from ascites revealed that the presence of paracrine IL-10 is not crucial for ascites-mediated suppression of DC activation in response to TLR activation. Unlike IL-10, PGE₂ is absent from peritoneal fluid of patients with benign conditions and selectively reduces TNFα induction in response to TLR-mediated activation in the presence of OC-associated ascites. Our study highlights PGE₂ as an immunosuppressive component of the malignant OC microenvironment rendering PGE₂ a potentially important target for immunotherapy in OC.

Production and Characterization of a Novel Monoclonal Antibody Against Human Sortilin

Sortilin, as a member of Vps10p-domain sorting receptor family, is overexpressed in a number of malignancies, including ovarian carcinoma. Antibodies against sortilin may contribute to further clarification of sortilin functional activities in signal transduction, intracellular sorting of proteins, and endocytosis. The aim of this study was to produce a monoclonal antibody against a synthetic peptide derived from extracellular N-terminal region of sortilin to be used as a tool for investigating sortilin characteristics in ovarian carcinoma. A synthetic peptide derived from the last 50 amino acids of extracellular domain of sortilin protein was selected and conjugated to keyhole limpet hemocyanin and used to immunize mice. The anti-sortilin monoclonal antibody (MAb), clone 2D8, was purified from supernatant of final hybridoma clone using peptide-affinity chromatography column. Reactivity of antibody with the immunizing peptide was assessed in ELISA. Furthermore, flow cytometry and Western blot analyses were used to investigate the reactivity of antibody with its target in a panel of ovarian carcinoma cell lines or tissues. MAb 2D8 was able to recognize the coated immunizing peptide in ELISA and detect its protein target, sortilin, in flow cytometry and Western blot analyses. The achieved data suggest that the developed monoclonal antibody may be applicable as a research tool for detection of sortilin protein in Western blot as well as flow cytometry tests.

Targeting AMPK signaling in combating ovarian cancers: opportunities and challenges

The development and strategic application of effective anticancer therapies have turned out to be one of the most critical approaches of managing human cancers. Nevertheless, drug resistance is the major obstacle for clinical management of these diseases especially ovarian cancer. In the past years, substantial studies have been carried out with the aim of exploring alternative therapeutic approaches to enhance efficacy of current chemotherapeutic regimes and reduce the side effects caused in order to produce significant advantages in overall survival and to improve patients' quality of life. Targeting cancer cell metabolism by the application of AMP-activated protein kinase (AMPK)-activating agents is believed to be one of the most plausible attempts. AMPK activators such as 5-aminoimidazole-4-carboxamide 1-β-d-ribofuranoside, A23187, metformin, and bitter melon extract not only prevent cancer progression and metastasis but can also be applied as a supplement to enhance the efficacy of cisplatin-based chemotherapy in human cancers such as ovarian cancer. However, because of the undesirable outcomes along with the frequent toxic side effects of most pharmaceutical AMPK activators that have been utilized in clinical trials, attentions of current studies have been aimed at the identification of replaceable reagents from nutraceuticals or traditional medicines. However, the underlying molecular mechanisms of many nutraceuticals in anticancer still remain obscure. Therefore, better understanding of the functional characterization and regulatory mechanism of natural AMPK activators would help pharmaceutical development in opening an area to intervene ovarian cancer and other human cancers.

IL‑6 and IL‑8 enhance factor H binding to the cell membranes

The aim of the present study was to assess the role of interleukin (IL)-6 and IL-8 on the expression of fluid-phase complement inhibitor, factor H (FH), and FH-like protein 1 (FHL-1), in the A2780 ovarian carcinoma cell line. This cell line does not normally produce IL-6, however, is IL-6 responsive due to the presence of receptor for IL-6. The presence of FH and FHL-1 in the cell lysates was confirmed by western blotting. The levels of FH and FHL-1 in the medium were determined by enzyme-linked immunosorbent assay. To evaluate gene expression, reverse transcription-quantitative polymerase chain reaction was performed. The cellular localization of FH and FHL-1 in ovarian cancer cells was assessed by immunofluorescence. The present study revealed that FH, contrary to FHL-1, was secreted by ovarian cancer cells, however, this process was independent of IL stimulation. No significant differences were observed in the concentration of FH in the control cells, when compared with the samples treated with IL-6/IL-8. The results of western blotting revealed that the protein expression levels of FH and FHL-1 were not regulated by IL-6 and IL-8 in a dose-dependent manner. Immunofluorescence analysis confirmed that the A2780 ovarian cancer cell line expressed both membrane bound and intracellular forms of FH and FHL-1. The present data revealed that the A2780 cells expressed and secreted FH protein and are also able to bind FH and FHL-1. This may influence the efficiency of complement mediated immunotherapy.

Newly recruited CD11b+, GR-1+, Ly6C(high) myeloid cells augment tumor-associated immunosuppression immediately following the therapeutic administration of oncolytic reovirus

Tumor-associated immunosuppression aids cancer cells to escape immune-mediated attack and subsequent elimination. Recently, however, many oncolytic viruses, including reovirus, have been reported to overturn such immunosuppression and promote the development of a clinically desired antitumor immunity, which is known to promote favorable patient outcomes. Contrary to this existing paradigm, in this article we demonstrate that reovirus augments tumor-associated immunosuppression immediately following its therapeutic administration. Our data show that reovirus induces preferential differentiation of highly suppressive CD11b(+), Gr-1(+), Ly6C(high) myeloid cells from bone marrow hematopoietic progenitor cells. Furthermore, reovirus administration in tumor-bearing hosts drives time-dependent recruitment of CD11b(+), Gr-1(+), Ly6C(high) myeloid cells in the tumor milieu, which is further supported by virus-induced increased expression of numerous immune factors involved in myeloid-derived suppressor cell survival and trafficking. Most importantly, CD11b(+), Gr-1(+), Ly6C(high) myeloid cells specifically potentiate the suppression of T cell proliferation and are associated with the absence of IFN-γ response in the tumor microenvironment early during oncotherapy. Considering that the qualitative traits of a specific antitumor immunity are largely dictated by the immunological events that precede its development, our findings are of critical importance and must be considered while devising complementary interventions aimed at promoting the optimum efficacy of oncolytic virus-based anticancer immunotherapies.

Ovarian cancer from an immune perspective

Despite major advances in the treatment of ovarian cancer over the past two decades, it is still an incurable disease and requires the development of better treatment strategies. In recent years, we have developed a greater understanding of tumor immunology and the interactions between tumors and the immune system. This has led to the emergence of cancer immunotherapy as the fourth treatment modality in cancer. In this article, we address the principles of immunotherapy and different approaches that have been investigated over the past decade and discuss the future of immune therapy in ovarian cancer.

Inhibition of HDAC1 and DNMT1 modulate RGS10 expression and decrease ovarian cancer chemoresistance

RGS10 is an important regulator of cell survival and chemoresistance in ovarian cancer. We recently showed that RGS10 transcript expression is suppressed during acquired chemoresistance in ovarian cancer. The suppression of RGS10 is due to DNA hypermethylation and histone deacetylation, two important mechanisms that contribute to silencing of tumor suppressor genes during cancer progression. Here, we fully investigate the molecular mechanisms of epigenetic silencing of RGS10 expression in chemoresistant A2780-AD ovarian cancer cells. We identify two important epigenetic regulators, HDAC1 and DNMT1, that exhibit aberrant association with RGS10 promoters in chemoresistant ovarian cancer cells. Knockdown of HDAC1 or DNMT1 expression, and pharmacological inhibition of DNMT or HDAC enzymatic activity, significantly increases RGS10 expression and cisplatin-mediated cell death. Finally, DNMT1 knock down also decreases HDAC1 binding to the RGS10 promoter in chemoresistant cells, suggesting HDAC1 recruitment to RGS10 promoters requires DNMT1 activity. Our results suggest that HDAC1 and DNMT1 contribute to the suppression of RGS10 during acquired chemoresistance and support inhibition of HDAC1 and DNMT1 as an adjuvant therapeutic approach to overcome ovarian cancer chemoresistance.

The effect of sortilin silencing on ovarian carcinoma cells

BACKGROUND

Our preliminary data on the protein expression of SORT1 in ovarian carcinoma tissues showed that sortilin was overexpressed in ovarian carcinoma patients and cell lines, while non-malignant ovaries expressed comparably lower amount of this protein. In spite of diverse ligands and also different putative functions of sortilin (NTR3), the function of overexpressed sortilin in ovarian carcinoma cells is an intriguing subject of inquiry. The aim of this study was, therefore, to investigate the functional role of sortilin in survival of ovarian carcinoma cell line.

METHODS

Expression of sortilin was knocked down using RNAi technology in the ovarian carcinoma cell line, Caov-4. Silencing of SORT1 expression was assessed using real-time qPCR and Western blot analyses. Apoptosis induction was evaluated using flow cytometry by considering annexin-V FITC binding. [(3)H]-thymidine incorporation assay was also used to evaluate cell proliferation capacity.

RESULTS

Real-time qPCR and Western blot analyses showed that expression of sortilin was reduced by nearly 70-80% in the siRNA transfected cells. Knocking down of sortilin expression resulted in increased apoptosis (27.5±0.48%) in siRNA-treated ovarian carcinoma cell line. Sortilin silencing led to significant inhibition of proliferation (40.1%) in siRNA-transfected Caov-4 cells as compared to mock control-transfected counterpart (p < 0.05).

CONCLUSION

As it was suspected from overexpression of sortilin in ovarian tumor cells, a cell survival role for sortilin can be deduced from these results. In conclusion, the potency of apoptosis induction via silencing of sortilin expression in tumor cells may introduce sortilin as a potential candidate for developing a novel targeted therapy in patients with ovarian carcinoma.

Cancer immunotherapy: are we there yet?

The immune system is the built-in host defense mechanism against infectious agents as well as cancer. Protective immunity against cancer was convincingly demonstrated in the 1940s with syngeneic animal models (JNCI 18:769-778, 1976; Cancer Immun 1:6, 2001). Since then, the last century’s dream has been to effectively prevent and cure cancers by immunological means. This dream has slowly but surely become a reality (Nature 480:480-489, 2011). The successful examples of immunoprophylaxis and therapy against cancers include: (i) targeted therapy using monoclonal antibodies (Nat Rev Cancer 12:278-287, 2012); (ii) allogeneic hematopoietic stem cell transplantion to elicit graft-versus-cancer effect against a variety of hematopoietic malignancies (Blood 112:4371-4383, 2008); (iii) vaccination for preventing cancers with clear viral etiology such as hepatocellular carcinoma and cervical cancer (Cancer J Clin 57:7-28, 2007; NEJM 336:1855-1859, 1997); (iv) T cell checkpoint blockade against inhibitory pathways including targeting CTLA-4 and PD-1 inhibitory molecules for the treatment of melanoma and other solid tumors (NEJM 363:711-723, 2010; NEJM 366:2443-2454, 2012; NEJM 369:122-133, 2013; NEJM 366:2455-2465, 2012); (v) antigen-pulsed autologous dendritic cell vaccination against prostate cancer (NEJM 363:411-422, 2010); and (vi) the transfer of T cells including those genetically engineered with chimeric antigen receptors allowing targeting of B cell neoplasms (NEJM 365:725-733, 2011; NEJM 368:1509-1518, 2013; Blood 118:4817-4828, 2013; Sci Transl Med 5:177ra138, 2013).

This article provides an overview on the exciting and expanding immunological arsenals against cancer, and discusses critical remaining unanswered questions of cancer immunology. The inherent specificity and memory of the adaptive immune response towards cancer will undoubtedly propel cancer immunotherapy to the forefront of cancer treatment in the immediate near future. Study of the fundamental mechanisms of the immune evasion of cancer shall also advance the field of immunology towards the development of effective immunotherapeutics against a wide spectrum of human diseases.

Gemcitabine enhances the efficacy of reovirus-based oncotherapy through anti-tumour immunological mechanisms

BACKGROUND

Reovirus preferentially infects and kills cancer cells and is currently undergoing clinical trials internationally. While oncolysis is the primary mode of tumour elimination, increasing evidence illustrates that reovirus additionally stimulates anti-tumour immunity with a capacity to target existing and possibly relapsing cancer cells. These virus-induced anti-tumour immune activities largely determine the efficacy of oncotherapy. On the other hand, anti-viral immune responses can negatively affect oncotherapy. Hence, the strategic management of anti-tumour and anti-viral immune responses through complementary therapeutics is crucial to achieve the maximum anti-cancer benefits of oncotherapy.

METHODS

Intra-peritoneal injection of mouse ovarian surface epithelial cells (ID8 cells) into wild-type C57BL/6 mice was treated with a therapeutic regimen of reovirus and/or gemcitabine and then analysed for prolonged survival, disease pathology, and various immunological parameters. Furthermore, in vitro analyses were conducted to assess apoptosis, viral spread, and viral production during reovirus and/or gemcitabine treatment.

RESULTS

We demonstrate that reovirus and gemcitabine combination treatment postpones peritoneal carcinomatosis development and prolongs the survival of cancer-bearing hosts. Importantly, these anti-cancer benefits are generated through various immunological mechanisms, including: (1) inhibition of myeloid-derived suppressor cells recruitment to the tumour microenvironment, (2) downmodulation of pro-MDSC factors, and (3) accelerated development of anti-tumour T-cell responses.

CONCLUSION

The complementation of reovirus with gemcitabine further potentiates virus-initiated anti-cancer immunity and enhances the efficacy of oncotherapy. In the context of ongoing clinical trials, our findings represent clinically relevant information capable of enhancing cancer outcomes.

HER2 expression beyond breast cancer: therapeutic implications for gynecologic malignancies

HER2 or ErbB2 is a member of the epidermal growth factor family and is overexpressed in subsets of breast, ovarian, gastric, colorectal, pancreatic, and endometrial cancers. HER2 regulates signaling through several pathways (Ras/Raf/mitogen-activated protein kinase and phosphatidylinositol-3 kinase/protein kinase B/mammalian target of rapamycin pathways) associated with cell survival and proliferation. HER2-overexpressed and/or gene-amplified tumors are generally regarded as biologically aggressive neoplasms. In breast, cervical, endometrial, and ovarian cancer, there have been several studies linking the amplification of the c-erbB2 gene with chemoresistance and overall poor survival. Tyrosine kinase inhibitors and immunotherapy with monoclonal antibodies targeting HER2 hold promise for patients harboring these aggressive neoplasms. Trastuzumab combined with cytotoxic chemotherapy agents or conjugated with radioactive isotopes is currently being investigated in clinical trials of several tumor types.

Increased CD70 expression is associated with clinical resistance to cisplatin-based chemotherapy and poor survival in advanced ovarian carcinomas

Background

CD70 has been regarded as a novel potential therapeutic target for multiple cancers. In this study, we characterized the expression of the CD70 protein in ovarian carcinomas and assessed its clinical-pathological prognostic value.

Materials and methods

The expression of CD70 in advanced ovarian cancer specimens was assessed by immunohistochemistry. Our results indicated that 16 out of 92 (17.4%) advanced ovarian serous carcinoma tumors showed a high level of CD70 expression. Furthermore, CD70 overexpression was significantly associated with cisplatin-based chemotherapy responses. The high CD70 expression subgroup demonstrated a higher incidence of chemotherapy resistance than the low CD70 subgroup (68.8% versus 25.0%, P = 0.001). Furthermore, univariate analysis conducted on subsets of ovarian carcinoma indicated that high CD70 expression was also associated with decreased survival rates; retained significance was observed on multivariate analysis.

Conclusion

Given the elevated expression of CD70 and its relationship with drug resistance and poor prognosis, our findings suggest that a minor proportion of ovarian carcinomas with CD70 overexpression might be a candidate for the emerging anti-CD70 antibody drug conjugates or therapeutic anti-CD70 antibodies.

Dendritic cell immunotherapy in ovarian cancer

Ovarian cancer is one of the most frequent gynecological malignancies. However, as there is no effective screening method to detect early disease, it is usually only diagnosed when already widespread in the abdomen. The majority of patients diagnosed with advanced-stage disease will relapse and require additional therapy. In the search for additional effective treatments for the management of recurrent disease, researchers have focused on the potential usefulness of immunotherapeutic modulation by administering autologous immune cells, such as dendritic cells (DCs), to stimulate antitumor host responses. With the ultimate goal of improved survival, this review addresses mechanisms in ovarian cancer that may limit the expansion of antitumor immunity, discusses the parameters to be considered for optimal DC immunotherapy, outlines evaluation methodology used to monitor the success of treatment regimens and reviews reported DC immunotherapy trials in ovarian cancer.

Expression of MAGE-C1/CT7 and selected cancer/testis antigens in ovarian borderline tumours and primary and recurrent ovarian carcinomas

MAGE-C1/CT7, NY-ESO-1, GAGE and MAGE-A4 are members of the cancer/testis (CT) antigen family, which have been proposed as potential targets for cancer immunotherapy. To determine the prevalence and biologic relevance of the novel CT antigen MAGE-C1/CT7 and other antigens, 36 ovarian borderline tumours (BTs), 230 primary ovarian carcinomas (OCs) and 80 recurrent OCs were immunohistochemically analysed using the monoclonal antibodies CT7-33 (MAGE-C1/CT7), E978 (NY-ESO-1), clone 26 (GAGE) and 57B (MAGE-A4). Positivity of at least one CT antigen was present in 39.5 % (81/205) of primary OC and in 50 % (26/52) of all recurrences. Expression of the novel CT antigen MAGE-C1/CT7 was most commonly seen with positivity in 24.5 % of primary and 35.1 % of recurrent OC. MAGE-A4, GAGE and NY-ESO-1 expressions were seen in 22.7, 13.9 and 7.1 % of primary and 22.6, 17.5 and 8.9 % of recurrent OC, respectively. Analysis of histological subtypes (serous, endometrioid, clear cell, mucinous and transitional) exhibited variable expression with negativity in all mucinous OC. High-grade serous OC revealed CT antigen expression in 5.6 to 28 % with MAGE-C1/CT7 being the most frequent, but without correlation with stage or overall survival. MAGE-C1/CT7 expression and coexpression of CT antigens were significantly correlated with grade of endometrioid OC. None of the BT showed CT antigen expression. No significant correlation was seen with stage, overall survival or response to chemotherapy. In summary, CT antigens are expressed in a certain subset of OC with no expression in BT or OC of mucinous histology. These findings may have implications for the design of polyvalent vaccination strategies for ovarian carcinomas.

Tumor Inhibition by DepoVax-Based Cancer Vaccine Is Accompanied by Reduced Regulatory/Suppressor Cell Proliferation and Tumor Infiltration

A successful cancer vaccine needs to overcome the effects of immune-suppressor cells such as Treg lymphocytes, suppressive cytokine-secreting Tr1 cells, and myeloid-derived suppressor cells (MDSCs), while enhancing tumor-specific immune responses. Given the relative poor efficacy associated with current cancer vaccines, a novel vaccine platform called DepoVax^TM (DPX) was developed. C3 tumor-challenged mice were immunized with HPV-E7 peptide in DPX- or conventional-emulsion- (CE-) based vaccine. While control mice showed marked increase in Treg/MDSCs in spleen and blood, in mice treated with DPX-E7 the levels remained similar to tumor-free naive mice. Such differences were also seen within the tumor. Antigen-specific IL10-secreting CD4/CD8 T cells and TGF-β⁺CD8⁺ T cell frequencies were increased significantly in CE-treated and control mice in contrast to DPX-E7-immunized mice. Analysis of tumor-infiltrating cells revealed higher frequency of suppressor cells in untreated controls than in DPX-E7 group while the converse was true for tumor-infiltrating CD8 T cells. Immunization of tumor-bearing HLA-A2 transgenic mice with human vaccine DPX-0907, a peptide-based vaccine for breast/ovarian/prostate cancers, showed efficient induction of immune response to cancer peptides despite the presence of suppressor cells. Thus, this study provides the rationale for using DPX-based cancer vaccines in immune-suppressed cancer patients, to induce effective anticancer immunity.

Immunotherapy in ovarian cancer

Ovarian cancer is the most deadly gynecologic malignancy, with more than 15,000 deaths anticipated in 2012. While approximately 80% of patients will respond to frontline chemotherapy, more than 60% of patients will experience disease recurrence and only 44% will be alive at 5 y. Host anti-tumor immune responses are associated with a significant improvement in overall survival for women with ovarian cancer. By bolstering these responses, it may therefore be possible to significantly influence the prognosis of women with this lethal disease. In this review, we will focus on innovative immune-based strategies which are currently being investigated in the treatment of ovarian cancer.

Ovarian serous carcinoma: recent concepts on its origin and carcinogenesis

Recent morphologic and molecular genetic studies have led to a paradigm shift in our conceptualization of the carcinogenesis and histogenesis of pelvic (non-uterine) serous carcinomas. It appears that both low-grade and high-grade pelvic serous carcinomas that have traditionally been classified as ovarian in origin, actually originate, at least in a significant subset, from the distal fallopian tube. Clonal expansions of the tubal secretory cell probably give rise to serous carcinomas, and the degree of ciliated conversion is a function of the degree to which the genetic hits deregulate normal differentiation. In this article, the authors review the evidentiary basis for aforementioned paradigm shift, as well as its potential clinical implications.

Current management and novel agents for malignant melanoma

Advanced malignant melanoma remains a challenging cancer. Over the past year, there have been 3 agents approved for treatment of melanoma by Food and Drug Administration. These include pegylated interferon alpha-2b for stage III melanoma, vemurafenib for unresectable or metastatic melanoma with BRAF V600E mutation, and ipilimumab for treatment of unresectable or metastatic melanoma. This review will also update on the development of novel agents, including tyrosine kinase inhibitors and adoptive cellular therapy.

Human tumour immune evasion via TGF-β blocks NK cell activation but not survival allowing therapeutic restoration of anti-tumour activity

Immune evasion is now recognized as a key feature of cancer progression. In animal models, the activity of cytotoxic lymphocytes is suppressed in the tumour microenvironment by the immunosuppressive cytokine, Transforming Growth Factor (TGF)-β. Release from TGF-β-mediated inhibition restores anti-tumour immunity, suggesting a therapeutic strategy for human cancer. We demonstrate that human natural killer (NK) cells are inhibited in a TGF-β dependent manner following chronic contact-dependent interactions with tumour cells in vitro. In vivo, NK cell inhibition was localised to the human tumour microenvironment and primary ovarian tumours conferred TGF-β dependent inhibition upon autologous NK cells ex vivo. TGF-β antagonized the interleukin (IL)-15 induced proliferation and gene expression associated with NK cell activation, inhibiting the expression of both NK cell activation receptor molecules and components of the cytotoxic apparatus. Interleukin-15 also promotes NK cell survival and IL-15 excluded the pro-apoptotic transcription factor FOXO3 from the nucleus. However, this IL-15 mediated pathway was unaffected by TGF-β treatment, allowing NK cell survival. This suggested that NK cells in the tumour microenvironment might have their activity restored by TGF-β blockade and both anti-TGF-β antibodies and a small molecule inhibitor of TGF-β signalling restored the effector function of NK cells inhibited by autologous tumour cells. Thus, TGF-β blunts NK cell activation within the human tumour microenvironment but this evasion mechanism can be therapeutically targeted, boosting anti-tumour immunity.

The comprehensive assessment of local immune status of ovarian cancer by the clustering of multiple immune factors

The aim of this study was to evaluate the local immune status of human ovarian cancers by the comprehensive analysis of tumor-infiltrating immune cells and immunosuppressive factors, and to elucidate the local immunity in clinical course. The numbers of CD1α+, CD4+, CD8+, CD57+, forkhead box P3+ and programmed cell death-1+ cells were counted, and the intensity of immunosuppressive factors, such as programmed cell death-1 ligand (PD-L)1, PD-L2, cyclooxygenase (COX)-1, COX-2 and transforming growth factor β1, were evaluated in 70 ovarian cancer specimens stained by immunohistochemistry. Then hierarchical clustering of these parameters showed the four clusters into ovarian cancer cases. Cluster 1, which had significantly better prognosis than the others, was characterized by high infiltration of CD4+ and CD8+ cells. In conclusion the comprehensive analysis of local immune status led to subdivide ovarian cancers into groups with better or worse prognoses and may guide precise understanding of the local immunity.

Myofibrillogenesis regulator 1 (MR-1) is a novel biomarker and potential therapeutic target for human ovarian cancer

Background

Myofibrillogenesis regulator 1 (MR-1) is overexpressed in human cancer cells and plays an essential role in cancer cell growth. However, the significance of MR-1 in human ovarian cancer has not yet been explored. The aim of this study was to examine whether MR-1 is a predictor of ovarian cancer and its value as a therapeutic target in ovarian cancer patients.

Methods

Reverse-transcription polymerase chain reaction (PCR) and quantitative real-time PCR were used to detect MR-1 mRNA levels in tissue samples from 26 ovarian cancer patients and 25 controls with benign ovarian disease. Anti-MR-1 polyclonal antibodies were prepared, tested by ELISA and western blotting, and then used for immunohistochemical analysis of the tissue samples. Adhesion and invasion of 292T cells was also examined after transfection of a pMX-MR-1 plasmid. Knockdown of MR-1 expression was achieved after stable transfection of SKOV3 cells with a short hairpin DNA pGPU6/GFP/Neo plasmid against the MR-1 gene. In addition, SKOV3 cells were treated with paclitaxel and carboplatin, and a potential role for MR-1 as a therapeutic target was evaluated.

Results

MR-1 was overexpressed in ovarian cancer tissues and SKOV3 cells. 293T cells overexpressed MR-1, and cellular spread and invasion were enhanced after transfection of the pMX-MR-1 plasmid, suggesting that MR-1 is critical for ovarian cancer cell growth. Knockdown of MR-1 expression inhibited cell adhesion and invasion, and treatment with anti-cancer drugs decreased its expression in cancer cells. Taken together, these results provide the first evidence of the cellular and molecular mechanisms by which MR-1 might serve as a novel biological marker and potential therapeutic target for ovarian cancer.

Conclusions

MR-1 may be a biomarker for diagnosis of ovarian cancer. It may also be useful for monitoring of the effects of anti-cancer therapies. Further studies are needed to clarify whether MR-1 is an early diagnostic marker for ovarian cancer and a possible therapeutic target.

Indoleamine 2,3-dioxygenase and immune tolerance in ovarian cancer

PURPOSE OF REVIEW

Ovarian cancer is the leading cause of cancer death among gynecologic malignancies despite significant advances in cytoreductive surgery and chemotherapy, and novel therapeutic approaches are urgently needed. Immunotherapy is one of these strategies; however, its clinical applications have shown limited efficacy. This may be attributed to tumor-induced immune tolerance, and much attention has been paid to overcoming these immune resistance mechanisms. This review focuses on the immunoregulatory enzyme indoleamine 2,3-dioxygenase (IDO) and shows the role of IDO and its clinical potential in ovarian cancer.

RECENT FINDINGS

IDO suppresses the proliferation of effector T cells or natural killer cells and their killer functions. In ovarian cancer, high IDO expression in tumor cells was correlated with a reduced number of tumor-infiltrating lymphocytes. The IDO expression was also correlated with advanced surgical stage and impaired survival. Preclinical studies in mice demonstrated that oral administration of IDO inhibitors suppressed peritoneal dissemination and potentiated the antitumor efficacy of chemotherapeutic agents.

SUMMARY

IDO induces immune tolerance and promotes ovarian cancer progression. Tumoral IDO expression is correlated with impaired clinical outcome. IDO inhibition may therefore be a promising strategy to restore host antitumor immunity and to enhance the antitumor potential of current chemotherapy or immunotherapy for advanced ovarian cancer.

Altered protein expression in serum from endometrial hyperplasia and carcinoma patients

BACKGROUND

Endometrial carcinoma is one of the most common gynecological malignancies in women. The diagnosis of the disease at early or premalignant stages is crucial for the patient's prognosis. To date, diagnosis and follow-up of endometrial carcinoma and hyperplasia require invasive procedures. Therefore, there is considerable demand for the identification of biomarkers to allow non-invasive detection of these conditions.

METHODS

In this study, we performed a quantitative proteomics analysis on serum samples from simple endometrial hyperplasia, complex endometrial hyperplasia, atypical endometrial hyperplasia, and endometrial carcinoma patients, as well as healthy women. Serum samples were first depleted of high-abundance proteins, labeled with isobaric tags (iTRAQ), and then analyzed via two-dimensional liquid chromatography and tandem mass spectrometry. Protein identification and quantitation information were acquired by comparing the mass spectrometry data against the International Protein Index Database using ProteinPilot software. Bioinformatics annotation of identified proteins was performed by searching against the PANTHER database.

RESULTS

In total, 74 proteins were identified and quantified in serum samples from endometrial lesion patients and healthy women. Using a 1.6-fold change as the benchmark, 12 proteins showed significantly altered expression levels in at least one disease group compared with healthy women. Among them, 7 proteins were found, for the first time, to be differentially expressed in atypical endometrial hyperplasia. These proteins are orosomucoid 1, haptoglobin, SERPINC 1, alpha-1-antichymotrypsin, apolipoprotein A-IV, inter-alpha-trypsin inhibitor heavy chain H4, and histidine-rich glycoprotein.

CONCLUSIONS

The differentially expressed proteins we discovered in this study may serve as biomarkers in the diagnosis and follow-up of endometrial hyperplasia and endometrial carcinoma.

Polyclonal antitumor immunoglobulin may play a role in ovarian cancer adjuvant therapy

Currently, surgery plus adjuvant chemotherapy are the mainstay of care in the treatment of ovarian cancer. Although this therapeutic strategy has been considered as "golden standard" regimen with profound impact on survival improvement, several obstacles have been encountered, such as chemotherapy drug resistance and disease relapse. Residual cancer cells in the abdominal cavity and vessels are considered as the main cause of disease relapse. New treatment options attempt to yield higher survival rate in patients. Monoclonal antibodies such as Trastuzumab and Cetuximab showed promising effects on several solid tumors. But for epithelial ovarian cancer, modalities of intravenous monoclonal antibody monotherapy have not achieved expected results as they have in the treatments of breast and colorectal cancer. Relatively low expression of matched receptors on ovarian cancer cells, as well as the intravenous delivery with less efficacy of intra-abdominal antibody accumulation, may account for lack of efficacy of monoclonal antibody on ovarian cancer. So we hypothesize that polyvalent antibodies boosted from rabbit by inoculating human tumor cells could deplete ovarian cancer cells through intraperitoneal route. The mechanisms may include interrupting ligand-receptor binding and thus result in blockage of intracellular signaling pathways such as EGFR and HER2 signal transduction, and possibly may also involve antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity.

Targeted treatment of recurrent platinum-resistant ovarian cancer: current and emerging therapies

With advances in surgical techniques and chemotherapeutic agents, mortality rates from epithelial ovarian cancer (EOC) have slightly decreased over the last 30 years. However, EOC still ranks as the most deadly gynecologic cancer with an overall 5-year survival rate of 45%. Prognosis is especially disappointing for women with platinum-resistant disease, where 80% of patients will fail to respond to available therapies. Emerging treatment strategies have sub-sequently focused on targets which are integral to tumor growth and metastasis. In this review, we will focus on those innovative agents currently under investigation in clinical trials.