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.

A prospective model of care for breast cancer rehabilitation : bone health and arthralgias

Musculoskeletal health can be compromised by breast cancer treatment. In particular, bone loss and arthralgias are prevalent side effects experienced by women treated with chemotherapy and/or adjuvant endocrine therapy. Bone loss leads to osteoporosis and related fractures, while arthralgias threaten quality of life and compliance to treatment. Because the processes that lead to these musculoskeletal problems are initiated when treatment begins, early identification of women who may be at higher risk of developing problems, routine monitoring of bone density and pain at certain stages of treatment, and prudent application of therapeutic interventions are key to preventing and/or minimizing musculoskeletal sequelae. Exercise may be a particularly suitable intervention strategy because of its potential to address a number of impairments; it may slow bone loss, appears to reduce joint pain in noncancer conditions, and improves other breast cancer outcomes. Research efforts continue in the areas of etiology, measurement, and treatment of bone loss and arthralgias. The purpose of this review is to provide an overview of the current knowledge on the management and treatment of bone loss and arthralgias in breast cancer survivors and to present a framework for rehabilitation care to preserve musculoskeletal health in women treated for breast cancer.

Breast cancer stem cells and epithelial mesenchymal plasticity : implications for chemoresistance

Tumour heterogeneity is a key characteristic of cancer and has significant implications relating to tumour response to chemotherapy as well as patient prognosis and potential relapse. It is being increasingly accepted that tumours are clonal in origin, suggestive of a tumour arising from a deregulated or mutated cell. Cancer stem cells (CSC) possess these capabilities, and with appropriate intracellular triggers and/or signalling from extracellular environments, can purportedly differentiate to initiate tumour formation. Additionally through epithelial mesenchymal plasticity (EMP), where cells gain and maintain characteristics of both epithelial and mesenchymal cell types, epithelial-derived tumour cells have been shown to de-differentiate to acquire cancer stem attributes, which also impart chemotherapy resistance. This new paradigm places EMP centrally in the process of tumour progression and metastasis, as well as modulating drug response to current forms of chemotherapy. Furthermore, EMP and CSCs have been identified in cancers arising from different tissue types making it a possible generic therapeutic target in cancer biology. Using breast cancer (BrCa) as an example, we summarise here the current understanding of CSCs, the role of EMP in cancer biology - especially in CSCs and different molecular subtypes, and the implications this has for current and future cancer treatment strategies.

Dormant but migratory tumour cells in desmoplastic stroma of invasive ductal carcinomas

Mortality in breast cancer is linked to metastasis and recurrence yet there is no acceptable biological model for cancer relapse. We hypothesise that there might exist primary tumour cells capable of escaping surgery by migration and resisting radiotherapy and chemotherapy to cause cancer recurrence. We investigated this possibility in invasive ductal carcinoma (IDC) tissue and observed the presence of solitary primary tumour cells (SPCs) in the dense collagen stroma that encapsulates intratumoural cells (ICs). In IDC tissue sections, collagen was detected with either Masson's Trichrome or by second harmonics imaging. Cytokeratin-19 (CK-19) and vimentin (VIM) antibodies were, respectively, used to identify epithelial-derived tumour cells and to indicate epithelial to mesenchymal transition (EMT). Confocal/multiphoton microscopy showed that ICs from acini were mainly CK-19 +ve and were encapsulated by dense stromal collagen. Within the stroma, SPCs were detected by their staining for both CK-19 and VIM (confirming EMT). ICs and SPCs were subsequently isolated by laser capture microdissection followed by multiplex tandem-PCR studies. SPCs were found to be enriched for pro-migratory and anti-proliferative genes relative to ICs. In vitro experiments using collagen matrices at 20 mg/cm 3, similar in density to tumour matrices, demonstrated that SPC-like cells were highly migratory but dormant, phenotypes that recapitulated the genotypes of SPCs in clinical tissue. These data suggest that SPCs located at the breast cancer perimeter are invasive and dormant such that they may exceed surgical margins and resist local and adjuvant therapies. This study has important connotations for a role of SPCs in local recurrence.

The effectiveness of information-sharing interventions as a means to reduce anxiety in families waiting for surgical patients undergoing an elective surgical procedure : a systematic review protocol

Review question/objective What are the most effective information sharing strategies used to reduce anxiety in families of patients undergoing elective surgery? This review seeks to synthesize the best available evidence in relation to the most effective information-sharing intervention to reduce anxiety for families waiting for patients undergoing an elective surgical procedure. The specific objectives are to review the effectiveness of evidence of interventions designed to reduce the anxiety of families waiting whilst their loved one undergoes a surgical intervention. A variety of interventions exist and include surgical nurse liaison services, intraoperative reporting either by face-to-face or telephone delivery, informational cards, visual information screens, and intraoperative paging devices for families. Inclusion criteria Types of participants All studies of family members over 18 years of age waiting for patients undergoing an elective surgical procedure will be included, including those waiting for both adult and paediatric patients. Studies of families waiting for other patient populations, eg emergency surgery, chemotherapy or intensive care patients will be excluded. Types of intervention(s)/phenomena of interest All information-sharing Interventions for families of patients undergoing an elective surgical procedure will be included, including but not limited to: surgical nurse liaison services, in-person intraoperative reporting, visual information screens, paging devices, informational cards and telephone delivery of intraoperative progress reports. Interventions that take place during the intraoperative phase of care only will be included in the review. Preadmission information sharing interventions will be excluded. Types of outcomes The outcomes of interest include: Primary outcome: the level of anxiety amongst family members or close relatives whilst waiting for patients undergoing surgery, as measured by a validated instrument (such as the S-Anxiety portion of the State-Trait Anxiety Inventory).4 Secondary outcomes: family satisfaction and other measurements that may be considered indicators of stress and anxiety, such as mean arterial pressure (MAP) and heart rate.

Cisplatin treatment of primary and metastatic epithelial ovarian carcinomas generates residual cells with mesenchymal stem cell-like profile

Epithelial mesenchymal transition (EMT) and cancer stem cells (CSC) have been associated with resistance to chemotherapy. Eighty percent of ovarian cancer patients initially respond to platinum-based combination therapy but most return with recurrence and ultimate demise. To better understand such chemoresistance we have assessed the potential role of EMT in tumor cells collected from advanced-stage ovarian cancer patients and the ovarian cancer cell line OVCA 433 in response to cisplatin in vitro. We demonstrate that cisplatin-induced transition from epithelial to mesenchymal morphology in residual cancer cells correlated with reduced E-cadherin, and increased N-cadherin and vimentin expression. The mRNA expression of Snail, Slug, Twist, and MMP-2 were significantly enhanced in response to cisplatin and correlated with increased migration. This coincided with increased cell surface expression of CSC-like markers such as CD44, α2 integrin subunit, CD117, CD133, EpCAM, and the expression of stem cell factors Nanog and Oct-4. EMT and CSC-like changes in response to cisplatin correlated with enhanced activation of extracellular signal-regulated kinase (ERK)1/2. The selective MEK inhibitor U0126 inhibited ERK2 activation and partially suppressed cisplatin-induced EMT and CSC markers. In vivo xenotransplantation of cisplatin-treated OVCA 433 cells in zebrafish embryos demonstrated significantly enhanced migration of cells compared to control untreated cells. U0126 inhibited cisplatin-induced migration of cells in vivo, suggesting that ERK2 signaling is critical to cisplatin-induced EMT and CSC phenotypes, and that targeting ERK2 in the presence of cisplatin may reduce the burden of residual tumor, the ultimate cause of recurrence in ovarian cancer patients.

Role of intratumoural heterogeneity in cancer drug resistance : molecular and clinical perspectives

Drug resistance continues to be a major barrier to the delivery of curative therapies in cancer. Historically, drug resistance has been associated with over-expression of drug transporters, changes in drug kinetics or amplification of drug targets. However, the emergence of resistance in patients treated with new-targeted therapies has provided new insight into the complexities underlying cancer drug resistance. Recent data now implicate intratumoural heterogeneity as a major driver of drug resistance. Single cell sequencing studies that identified multiple genetically distinct variants within human tumours clearly demonstrate the heterogeneous nature of human tumours. The major contributors to intratumoural heterogeneity are (i) genetic variation, (ii) stochastic processes, (iii) the microenvironment and (iv) cell and tissue plasticity. Each of these factors impacts on drug sensitivity. To deliver curative therapies to patients, modification of current therapeutic strategies to include methods that estimate intratumoural heterogeneity and plasticity will be essential.

The biology of breast tumor progression : acquisition of hormone independence and resistance to cytotoxic drugs

Many breast tumors appear to follow a predictable clinical pattern, being initially responsive to endocrine therapy and to cytotoxic chemotherapy but ultimately exhibiting a phenotype resistant to both modalities. Using the MCF-7 human breast cancer cell line as an example of an 'early' phenotype (estrogen and progesterone receptor positive, steroid responsive, low metastatic potential), we have isolated and characterized a series of hormone-independent but hormone-responsive variants (MIII and MCF7/LCC1). However, these variants remain responsive to both antiestrogens and cytotoxic drugs (methotrexate and colchicine). MIII and MCF7/LCCl cells appear to mimic some of the critical aspects of the early progression to a more aggressive phenotype. An examination of the phenotype of these cells suggests that some hormone-independent breast cancer cells are derived from hormone-dependent parental cells. The development of a hormone-independent phenotype can arise independently of acquisition of a cytotoxic drug resistant phenotype.

Fatty acid synthesis and pyruvate metabolism pathways remain active in dihydroartemisinin induced dormant ring stages of Plasmodium falciparum

Artemisinin (ART) based combination therapy (ACT) is used as the first line treatment of uncomplicated falciparum malaria worldwide. However, despite high potency and rapid action there is a high rate of recrudescence associated with ART monotherapy or ACT long before the recent emergence of ART resistance. ART induced ring stage dormancy and recovery has been implicated as possible cause of recrudescence; however, little is known about the characteristics of dormant parasites including whether dormant parasites are metabolically active. We investigated the transcription of 12 genes encoding key enzymes in various metabolic pathways in P. falciparum during dihydroartemisinin (DHA) induced dormancy and recovery. Transcription analysis showed an immediate down regulation for 10 genes following exposure to DHA, but continued transcription of 2 genes encoding apicoplast and mitochondrial proteins. Transcription of several additional genes encoding apicoplast and mitochondrial proteins, particularly genes encoding enzymes in pyruvate metabolism and fatty acid synthesis pathways, were also maintained. Additions of inhibitors for biotin acetyl CoA carbozylase and enoyl-acyl carrier reductase of the fatty acid synthesis pathways delayed the recovery of dormant parasites by 6 and 4 days, respectively following DHA treatment. Our results demonstrate most metabolic pathways are down regulated in DHA induced dormant parasites. In contrast fatty acid and pyruvate metabolic pathways remain active. These findings highlight new targets to interrupt recovery of parasites from ART-induced dormancy and to reduce the rate of recrudescence following ART treatment.

Irradiation, cisplatin, and 5-azacytidine upregulate cytomegalovirus promoter in tumors and muscles: Implementation of non-invasive fluorescence imaging

Purpose: The cytomegalovirus (CMV) promoter is one of the most commonly used promoters for expression of transgenes in mammalian cells. The aim of our study was to evaluate the role of methylation and upregulation of the CMV promoter by irradiation and the chemotherapeutic agent cisplatin in vivo using non-invasive fluorescence in vivo imaging. Procedures: Murine fibrosarcoma LPB and mammary carcinoma TS/A cells were stably transfected with plasmids encoding CMV and p21 promoter-driven green fluorescent protein (GFP) gene. Solid TS/A tumors were induced by subcutaneous injection of fluorescent tumor cells, while leg muscles were transiently transfected with plasmid encoding GFP under the control of the CMV promoter. Cells, tumors, and legs were treated either by DNA methylation inhibitor 5-azacytidine, irradiation, or cisplatin. GFP expression was determined using a fluorescence microplate reader in vitro and by non-invasive fluorescence imaging in vivo. Results: Treatment of cells, tumors, and legs with 5-azacytidine (re)activated the CMV promoter. Furthermore, treatment with irradiation or cisplatin resulted in significant upregulation of GFP expression both in vitro and in vivo. Conclusions: Observed alterations in the activity of the CMV promoter limit the usefulness of this widely used promoter as a constitutive promoter. On the other hand, inducibility of CMV promoters can be beneficially used in gene therapy when combined with standard cancer treatment, such as radiotherapy and chemotherapy. © 2010 The Author(s).

Anti-proliferative and cytotoxic activity of pentadactylin isolated from Leptodactylus labyrinthicus on melanoma cells

Nowadays, the emergence of resistance to the current available chemotherapeutic drugs by cancer cells makes the development of new agents imperative. The skin secretion of amphibians is a natural rich source of antimicrobial peptides (AMP), and researchers have shown that some of these wide spectrum molecules are also toxic to cancer cells. The aim of this study was to verify a putative anticancer activity of the AMP pentadactylin isolated for the first time from the skin secretion of the frog Leptodactylus labyrinthicus and also to study its cytotoxic mechanism to the murine melanoma cell line B16F10. The results have shown that pentadactylin reduces the cell viability of B16F10 cells in a dose-dependent manner. It was also cytotoxic to normal human fibroblast cells; nevertheless, pentadactylin was more potent in the first case. The studies of action mechanism revealed that pentadactylin causes cell morphology alterations (e.g., round shape and shrinkage morphology), membrane disruption, DNA fragmentation, cell cycle arrest at the S phase, and alteration of mitochondrial membrane potential, suggesting that B16F10 cells die by apoptosis. The exact mechanism that causes reduction of cell viability and cytotoxicity after treatment with pentadactylin is still unknown. In conclusion, as cancer cells become resilient to death, it is worthwhile the discovery of new drugs such as pentadactylin that induces apoptosis.

Inhibition of the JAK2/STAT3 pathway in ovarian cancer results in the loss of cancer stem cell-like characteristics and a reduced tumor burden

Background Current treatment of ovarian cancer patients with chemotherapy leaves behind a residual tumor which results in recurrent ovarian cancer within a short time frame. We have previously demonstrated that a single short-term treatment of ovarian cancer cells with chemotherapy in vitro resulted in a cancer stem cell (CSC)-like enriched residual population which generated significantly greater tumor burden compared to the tumor burden generated by control untreated cells. In this report we looked at the mechanisms of the enrichment of CSC-like residual cells in response to paclitaxel treatment. Methods The mechanism of survival of paclitaxel-treated residual cells at a growth inhibitory concentration of 50% (GI50) was determined on isolated tumor cells from the ascites of recurrent ovarian cancer patients and HEY ovarian cancer cell line by in vitro assays and in a mouse xenograft model. Results Treatment of isolated tumor cells from the ascites of ovarian cancer patients and HEY ovarian cancer cell line with paclitaxel resulted in a CSC-like residual population which coincided with the activation of Janus activated kinase 2 (JAK2) and signal transducer and activation of transcription 3 (STAT3) pathway in paclitaxel surviving cells. Both paclitaxel-induced JAK2/STAT3 activation and CSC-like characteristics were inhibited by a low dose JAK2-specific small molecule inhibitor CYT387 (1 μM) in vitro. Subsequent, in vivo transplantation of paclitaxel and CYT387-treated HEY cells in mice resulted in a significantly reduced tumor burden compared to that seen with paclitaxel only-treated transplanted cells. In vitro analysis of tumor xenografts at protein and mRNA levels demonstrated a loss of CSC-like markers and CA125 expression in paclitaxel and CYT387-treated cell-derived xenografts, compared to paclitaxel only-treated cell-derived xenografts. These results were consistent with significantly reduced activation of JAK2 and STAT3 in paclitaxel and CYT387-treated cell-derived xenografts compared to paclitaxel only-treated cell derived xenografts. Conclusions This proof of principle study demonstrates that inhibition of the JAK2/STAT3 pathway by the addition of CYT387 suppresses the ‘stemness’ profile in chemotherapy-treated residual cells in vitro, which is replicated in vivo, leading to a reduced tumor burden. These findings have important implications for ovarian cancer patients who are treated with taxane and/or platinum-based therapies. Keywords: Ovarian carcinoma, Cancer stem cell, Metastasis, Ascites, Chemoresistance, Recurrence, JAK2/STAT3 pathway

Targeted disruption of the JAK2/STAT3 pathway in combination with systemic administration of paclitaxel inhibits the priming of ovarian cancer stem cells leading to a reduced tumor burden

Chemotherapy resistance associated with recurrent disease is the major cause of poor survival of ovarian cancer patients. We have recently demonstrated activation of the JAK2/STAT3 pathway and the enhancement of a cancer stem cell (CSC)-like phenotype in ovarian cancer cells treated in vitro with chemotherapeutic agents. To elucidate further these mechanisms in vivo,we used a two-tiered paclitaxel treatment approach in nude mice inoculated with ovarian cancer cells. In the first approach, we demonstrate that a single intraperitoneal administration of paclitaxel in mice 7 days after subcutaneous transplantation of the HEY ovarian cancer cell line resulted in a significant increase in the expression of CA125, Oct4, and CD117 in mice xenografts compared to control mice xenografts which did not receive paclitaxel. In the second approach, mice were administered once weekly with paclitaxel and/or a daily dose of the JAK2-specific inhibitor, CYT387, over 4weeks. Mice receiving paclitaxel only demonstrated a significant decrease in tumor volume compared to control mice. At the molecular level, mouse tumors remaining after paclitaxel administration showed a significant increase in the expression of Oct4 and CD117 coinciding with a significant activation of the JAK2/STAT3 pathway compared to control tumors. The addition of CYT387 with paclitaxel resulted in the suppression of JAK2/STAT3 activation and abrogation of Oct4 and CD117 expression in mouse xenografts. This coincided with significantly smaller tumors in mice administered CYT387 in addition to paclitaxel, compared to the control group and the group of mice receiving paclitaxel only. These data suggest that the systemic administration of paclitaxel enhances Oct4- and CD117-associated CSC-like marker expression in surviving cancer cells in vivo, which can be suppressed by the addition of the JAK2-specific inhibitor CYT387, leading to a significantly smaller tumor burden. These novel findings have the potential for the development of CSC-targeted therapy to improve the treatment outcomes of ovarian cancer patients.

Treatment with the vascular disruptive agent OXi4503 induces an immediate and widespread epithelial to mesenchymal transition in the surviving tumor

Epithelial to mesenchymal transition (EMT) is considered an important mechanism in tumor resistance to drug treatments; however, in vivo observation of this process has been limited. In this study we demonstrated an immediate and widespread EMT involving all surviving tumor cells following treatment of a mouse model of colorectal liver metastases with the vascular disruptive agent OXi4503. EMT was characterized by significant downregulation of E-cadherin, relocation and nuclear accumulation of b-catenin as well as significant upregulation of ZEB1 and vimentin. Concomitantly, significant temporal upregulation in hypoxia and the pro-angiogenic growth factors hypoxia-inducible factor 1-alpha, hepatocyte growth factor, vascular endothelial growth factor and transforming growth factor-beta were seen within the surviving tumor. The process of EMT was transient and by 5 days after treatment tumor cell reversion to epithelial morphology was evident. This reversal, termed mesenchymal to epithelial transition (MET) is a process implicated in the development of new metastases but has not been observed in vivo histologically. Similar EMT changes were observed in response to other antitumor treatments including chemotherapy, thermal ablation, and antiangiogenic treatments in our mouse colorectal metastasis model and in a murine orthotopic breast cancer model after OXi4503 treatment. These results suggest that EMT may be an early mechanism adopted by tumors in response to injury and hypoxic stress, such that inhibition of EMT in combination with other therapies could play a significant role in future cancer therapy.

Chemotherapeutic compounds targeting the DNA double-strand break repair pathways : the good, the bad, and the promising

The repair of DNA double-strand breaks (DSBs) is a critical cellular mechanism that exists to ensure genomic stability. DNA DSBs are the most deleterious type of insult to a cell’s genetic material and can lead to genomic instability, apoptosis, or senescence. Incorrectly repaired DNA DSBs have the potential to produce chromosomal translocations and genomic instability, potentially leading to cancer. The prevalence of DNA DSBs in cancer due to unregulated growth and errors in repair opens up a potential therapeutic window in the treatment of cancers. The cellular response to DNA DSBs is comprised of two pathways to ensure DNA breaks are repaired: homologous recombination and non-homologous end joining. Identifying chemotherapeutic compounds targeting proteins involved in these DNA repair pathways has shown promise as a cancer therapy for patients, either as a monotherapy or in combination with genotoxic drugs. From the beginning, there have been a number of chemotherapeutic compounds that have yielded successful responses in the clinic, a number that have failed (CGK-733 and iniparib), and a number of promising targets for future studies identified. This review looks in detail at how the cell responds to these DNA DSBs and investigates the chemotherapeutic avenues that have been and are currently being explored to target this repair process.