Clinical Application of Poly(ADP-Ribose) Polymerase Inhibitors in High-Grade Serous Ovarian Cancer

: High-grade serous ovarian cancer is characterized by genomic instability, with one half of all tumors displaying defects in the important DNA repair pathway of homologous recombination. Given the action of poly(ADP-ribose) polymerase (PARP) inhibitors in targeting tumors with deficiencies in this repair pathway by loss of BRCA1/2, ovarian tumors could be an attractive population for clinical application of this therapy. PARP inhibitors have moved into clinical practice in the past few years, with approval from the Food and Drug Administration (FDA) and European Medicines Agency (EMA) within the past 2 years. The U.S. FDA approval of olaparib applies to fourth line treatment in germline BRCA-mutant ovarian cancer, and European EMA approval to olaparib maintenance in both germline and somatic BRCA-mutant platinum-sensitive ovarian cancer. In order to widen the ovarian cancer patient population that would benefit from PARP inhibitors, predictive biomarkers based on a clear understanding of the mechanism of action are required. Additionally, a better understanding of the toxicity profile is needed if PARP inhibitors are to be used in the curative, rather than the palliative, setting. We reviewed the development of PARP inhibitors in phase I-III clinical trials, including combination trials of PARP inhibitors and chemotherapy/antiangiogenics, the approval for these agents, the mechanisms of resistance, and the outstanding issues, including the development of biomarkers and the rate of long-term hematologic toxicities with these agents.

IMPLICATIONS FOR PRACTICE: The poly(ADP-ribose) polymerase (PARP) inhibitor olaparib has recently received approval from the Food and Drug Administration (FDA) and European Medicines Agency (EMA), with a second agent (rucaparib) likely to be approved in the near future. However, the patient population with potential benefit from PARP inhibitors is likely wider than that of germline BRCA mutation-associated disease, and biomarkers are in development to enable the selection of patients with the potential for clinical benefit from these agents. Questions remain regarding the toxicities of PARP inhibitors, limiting the use of these agents in the prophylactic or adjuvant setting until more information is available. The indications for olaparib as indicated by the FDA and EMA are reviewed.

Obesity induced by high-fat diet promotes insulin resistance in the ovary

Besides the effects on peripheral energy homeostasis, insulin also has an important role in ovarian function. Obesity has a negative effect on fertility, and may play a role in the development of the polycystic ovary syndrome in susceptible women. Since insulin resistance in the ovary could contribute to the impairment of reproductive function in obese women, we evaluated insulin signaling in the ovary of high-fat diet-induced obese rats. Female Wistar rats were submitted to a high-fat diet for 120 or 180 days, and the insulin signaling pathway in the ovary was evaluated by immunoprecipitation and immunoblotting. At the end of the diet period, we observed insulin resistance, hyperinsulinemia, an increase in progesterone serum levels, an extended estrus cycle, and altered ovarian morphology in obese female rats. Moreover, in female obese rats treated for 120 days with the high-fat diet, the increase in progesterone levels occurred together with enhancement of LH levels. The ovary from high-fat-fed female rats showed a reduction in the insulin receptor substrate/phosphatidylinositol 3-kinase/AKT intracellular pathway, associated with an increase in FOXO3a, IL1B, and TNF alpha protein expression. These changes in the insulin signaling pathway may have a role in the infertile state associated with obesity. Journal of Endocrinology (2010) 206, 65-74

Effect of total abdominal hysterectomy on ovarian blood supply in women of reproductive age

Objective. The purpose of this study was to evaluate the effect of total abdominal hysterectomy on ovarian blood supply using transvaginal color Doppler ultrasonography in women of reproductive age. Methods. This prospective study included 61 women aged 40 years or younger who were divided into 2 groups: group 1, comprising 31 patients who underwent total abdominal hysterectomy (TAH), and group 2, comprising 30 women with no abnormalities. Inclusion criteria included normal ovarian function at baseline, with basal follicle-stimulating hormone levels of less than 15 mUI/mL, normal body weight, no tobacco use, and no history of laparotomy or ovarian disease. Ovarian arterial blood supply by determination of the pulsatility index (PI) on Doppler analysis and ovarian volume on transvaginal ultrasonography were assessed at baseline and at 6 and 12 postoperative months. The Student t test, profile analysis, and Friedman and Mann-Whitney tests were used in the statistical analysis of data. Results. Statistical analysis of baseline data revealed that both groups were homogeneous. At months 6 and 12, greater ovarian volumes and lower PI values were observed in patients who underwent TAH (P < .05). By the end of the study, in 8 of the 31 patients who underwent TAH (25.5%), benign ovarian cysts were observed. in the control group, all the parameters studied remained unchanged. Conclusions. The reduced PI values observed on Doppler ultrasonography suggested a decrease in the resistance flow in the ovarian arteries in women of reproductive age who underwent TAH.

Ovarian and uterine periovulatory Doppler ultrasonography in bitches

Este trabalho teve como objetivo descrever as características ultrassonográficas uterinas e ovarianas, e dopplervelocimétricas das suas artérias nos dias periovulatórios em cadelas. Quinze ciclos estrais em 10 animais foram avaliados. As características ultrassonográficas, índices de resistência (IR) e índices de pulsatilidade (IP) do útero e dos ovários em cada animal foram registrados 5 dias antes e depois da ovulação (D0). Os dados foram analisados estatisticamente e os resultados foram expressos em média ± erro padrão da média (P<0,05). Como resultados as características ultrassonográficas uterinas foram semelhantes em todos os ciclos e dias avaliados, tendo o corpo uterino um diâmetro médio de 0,85±0,02cm. Foi observado um aumento no volume dos ovários e nos diâmetros dos folículos, tendo os ovários um volume de 0,64±0,06cm³, e a cavidade dos folículos um diâmetro de 0,46±0,01cm no dia da ovulação. Após a ovulação, foi observado colapso dos folículos somente em alguns ciclos. A perfusão sanguínea uterina diminuiu dois dias antes da ovulação e permaneceu inalterada até a ovulação. Após a ovulação, houve um aumento gradual na perfusão das artérias uterinas e ovarianas, direcionando o fluxo de sangue para os ovários e aumentando a perfusão da artéria intra-ovariana um dia após a ovulação. Conclui-se que características específicas são observadas na imagem ultrassonográfica uterina e ovariana, e dopplervelocimétricas de suas artérias nos dias periovulatórios, e quando associadas permitem estimar com mais precisão o dia da ovulação.

Empirical chemosensitivity testing in a spheroid model of ovarian cancer using a microfluidics-based multiplex platform.

The use of biomarkers to infer drug response in patients is being actively pursued, yet significant challenges with this approach, including the complicated interconnection of pathways, have limited its application. Direct empirical testing of tumor sensitivity would arguably provide a more reliable predictive value, although it has garnered little attention largely due to the technical difficulties associated with this approach. We hypothesize that the application of recently developed microtechnologies, coupled to more complex 3-dimensional cell cultures, could provide a model to address some of these issues. As a proof of concept, we developed a microfluidic device where spheroids of the serous epithelial ovarian cancer cell line TOV112D are entrapped and assayed for their chemoresponse to carboplatin and paclitaxel, two therapeutic agents routinely used for the treatment of ovarian cancer. In order to index the chemoresponse, we analyzed the spatiotemporal evolution of the mortality fraction, as judged by vital dyes and confocal microscopy, within spheroids subjected to different drug concentrations and treatment durations inside the microfluidic device. To reflect microenvironment effects, we tested the effect of exogenous extracellular matrix and serum supplementation during spheroid formation on their chemotherapeutic response. Spheroids displayed augmented chemoresistance in comparison to monolayer culturing. This resistance was further increased by the simultaneous presence of both extracellular matrix and high serum concentration during spheroid formation. Following exposure to chemotherapeutics, cell death profiles were not uniform throughout the spheroid. The highest cell death fraction was found at the center of the spheroid and the lowest at the periphery. Collectively, the results demonstrate the validity of the approach, and provide the basis for further investigation of chemotherapeutic responses in ovarian cancer using microfluidics technology. In the future, such microdevices could provide the framework to assay drug sensitivity in a timeframe suitable for clinical decision making.

Therapeutic Targeting of ATP7B in Ovarian Carcinoma.

PURPOSE: Resistance to platinum chemotherapy remains a significant problem in ovarian carcinoma. Here, we examined the biological mechanisms and therapeutic potential of targeting a critical platinum resistance gene, ATP7B, using both in vitro and in vivo models. EXPERIMENTAL DESIGN: Expression of ATP7A and ATP7B was examined in ovarian cancer cell lines by real-time reverse transcription-PCR and Western blot analysis. ATP7A and ATP7B gene silencing was achieved with targeted small interfering RNA (siRNA) and its effects on cell viability and DNA adduct formation were examined. For in vivo therapy experiments, siRNA was incorporated into the neutral nanoliposome 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC). RESULTS: ATP7A and ATP7B genes were expressed at higher levels in platinum-resistant cells compared with sensitive cells; however, only differences in ATP7B reached statistical significance. ATP7A gene silencing had no significant effect on the sensitivity of resistant cells to cisplatin, but ATP7B silencing resulted in 2.5-fold reduction of cisplatin IC(50) levels and increased DNA adduct formation in cisplatin-resistant cells (A2780-CP20 and RMG2). Cisplatin was found to bind to the NH(2)-terminal copper-binding domain of ATP7B, which might be a contributing factor to cisplatin resistance. For in vivo therapy experiments, ATP7B siRNA was incorporated into DOPC and was highly effective in reducing tumor growth in combination with cisplatin (70-88% reduction in both models compared with controls). This reduction in tumor growth was accompanied by reduced proliferation, increased tumor cell apoptosis, and reduced angiogenesis. CONCLUSION: These data provide a new understanding of cisplatin resistance in cancer cells and may have implications for therapeutic reversal of drug resistance.

PARP Inhibitor Resistance - What Is Beyond BRCA1 or BRCA2 Restoration?

Nearly 10 years ago the usefulness of poly(ADP-ribose) polymerase (PARP) inhibitors to kill BRCA1 or BRCA2-deficient cells was reported, and this finding has served as a prime example of the concept of synthetic lethality in the context of anticancer therapy. The clinical translation of this finding has undergone several ups and downs, however. Despite spectacular responses seen in some patients with BRCA-deficient breast or ovarian cancers, other patients did not show the expected benefit from PARP inhibitor therapy. Thus, like for all novel tailored anti-cancer drugs, upfront and secondary resistance remain major hurdles in the implementation of the initial preclinical finding. We know at least one clinically relevant mechanism of PARP inhibitor resistance: the reversion of BRCA function by secondary mutations. Nevertheless, it is also clear that this mechanism does not explain all cases of resistance. At the moment, we only have a poor understanding of BRCA reversion-independent resistance mechanisms. Preclinical data have pointed in several directions, e.g. increased drug efflux, reduced drug target levels, or alternative DNA repair. Here, we discuss these mechanisms with a focus on potential DNA repair adaptations.

Circulating tumor cells as trigger to hematogenous spreads and potential biomarkers to predict the prognosis in ovarian cancer.

Despite several improvements in the surgical field and in the systemic treatment, ovarian cancer (OC) is still characterized by high recurrence rates and consequently poor survival. In OC, there is still a great lack of knowledge with regard to cancer behavior and mechanisms of recurrence, progression, and drug resistance. The OC metastatization process mostly occurs via intracoelomatic spread. Recent evidences show that tumor cells generate a favorable microenvironment consisting in T regulatory cells, T infiltrating lymphocytes, and cytokines which are able to establish an "immuno-tolerance mileau" in which a tumor cell can become a resistant clone. When the disease responds to treatment, immunoediting processes and cancer progression have been stopped. A similar inhibition of the immunosuppressive microenvironment has been observed after optimal cytoreductive surgery as well. In this scenario, the early identification of circulating tumor cells could represent a precocious signal of loss of the immune balance that precedes cancer immunoediting and relapse. Supporting this hypothesis, circulating tumor cells have been demonstrated to be a prognostic factor in several solid tumors such as colorectal, pancreatic, gastric, breast, and genitourinary cancer. In OC, the role of circulating tumor cells is still to be defined. However, as opposed to healthy women, circulating tumor cells have been demonstrated in peripheral blood of OC patients, opening a new research field in OC diagnosis, treatment monitoring, and follow-up.

Identification of semaphorin E as a non-MDR drug resistance gene of human cancers

To improve cancer chemotherapy, a better understanding of the molecular mechanisms of drug resistance is essential. To identify the molecules responsible for drug resistance that is unrelated to MDR1 or MRP gene products, a eukaryotic expression cDNA library of cis-diamminedichloroplatinum(II) (CDDP)-resistant ovarian cancer TYKnuR cells was introduced into Cos-7 cells. After repeated CDDP selection, cDNA homologous to murine semaphorin E was isolated from surviving cells. Human semaphorin E (H-sema E) was overexpressed in CDDP-resistant cell lines and was readily induced not only by diverse chemotherapeutic drugs but also by x-ray and UV irradiation. Transfection of H-sema E conferred a drug-resistant phenotype to CDDP-sensitive cells. In addition, the aberrant expression of H-sema E protein was detected immunohistochemically in 14 of 42 (33.3%) recurrent squamous cell carcinomas removed at autopsy after extensive radiochemotherapy. Recently, another member of the semaphorin family, CD100, was shown to significantly improve the viability of B lymphocytes. These results suggest the involvement of semaphorins in diverse cell survival mechanisms.

ROLE OF STAT1 AND CXCL10 IN THE TUMOUR IMMUNE MICROENVIRONMENT OF HIGH-GRADE SEROUS OVARIAN CANCER

High-grade serous ovarian cancer (HGSC) is the most prevalent epithelial ovarian cancer characterized by late detection, metastasis and resistance to chemotherapy. Previous studies on the tumour immune microenvironment in HGSC identified STAT1 and CXCL10 as the most differentially expressed genes between treatment naïve chemotherapy resistant and sensitive tumours. Interferon-induced STAT1 is a transcription factor, which induces many genes including tumour suppressor genes and those involved in recruitment of immune cells to the tumour immune microenvironment (TME), including CXCL10. CXCL10 is a chemokine that recruits tumour infiltrating lymphocytes (TILs) and exhibits angiostatic function. The current study was performed to determine the effects of differential STAT1 and CXCL10 expression on HGSC disease progression and TME. STAT1 expression and intratumoural CD8+ T cells were evaluated as prognostic and predictive biomarkers via immunohistochemistry on 734 HGSC tumours accrued from the Terry Fox Research Institute-Canadian Ovarian Experimental Unified Resource. The combined effect of STAT1 expression and CD8+ TIL density was confirmed as prognostic and predictive companion biomarkers in the second independent biomarker validation study. Significant positive correlation between STAT1 expression and intratumoral CD8+ TIL density was observed. The effects of enforced CXCL10 expression on HGSC tumour growth, vasculature and immune tumour microenvironment were studied in the ID8 mouse ovarian cancer cell engraftment in immunocompetent C57BL/6 mice. Significant decrease in tumour progression in mice injected with ID8 CXCL10 overexpressing cells compared to mice injected with ID8 vector control cells was observed. Multiplexed cytokine analysis of ascites showed differential expression of IL-6, VEGF and CXCL9 between the two groups. Endothelial cell marker staining showed differences in tumour vasculature between the two groups. Immune transcriptomic profiling identified distinct expression profiles in genes associated with cytokines, chemokines, interferons, T cell function and apoptosis between the two groups. These findings provide evidence that STAT1 is an independent biomarker and in combination with CD8+ TIL density could be applied as novel immune-based biomarkers in HGSC. These results provide the basis for future studies aimed at understanding mechanisms underlying differential tumour STAT1 and CXCL10 expression and its role in pre-existing tumour immunologic diversity, thus potentially contributing to biomarker guided immune modulatory therapies.

A novel mechanism of action of HER2 targeted immunotherapy is explained by inhibition of NRF2 function in ovarian cancer cells

Nuclear erythroid related factor-2 (NRF2) is known to promote cancer therapeutic detoxification and crosstalk with growth promoting pathways. HER2 receptor tyrosine kinase is frequently overexpressed in cancers leading to uncontrolled receptor activation and signaling. A combination of HER2 targeting monoclonal antibodies shows greater anticancer efficacy than the single targeting antibodies, however, its mechanism of action is largely unclear. Here we report novel actions of anti-HER2 drugs, Trastuzumab and Pertuzumab, involving NRF2. HER2 targeting by antibodies inhibited growth in association with persistent generation of reactive oxygen species (ROS), glutathione (GSH) depletion, reduction in NRF2 levels and inhibition of NRF2 function in ovarian cancer cell lines. The combination of antibodies produced more potent effects than single alone; downregulated NRF2 substrates by repressing the Antioxidant Response (AR) pathway with concomitant transcriptional inhibition of NRF2. We showed the antibody combination produced increased methylation at the NRF2 promoter consistent with repression of NRF2 antioxidant function, as HDAC and methylation inhibitors reversed such produced transcriptional effects. These findings demonstrate a novel mechanism and role for NRF2 in mediating the response of cancer cells to the combination of Trastuzumab and Pertuzumab and reinforce the importance of NRF2 in drug resistance and as a key anticancer target.

Smoothing a Discrete Hazard Function for the Number of Patients Colonized with Methicillin-Resistance Staphylococcus Aureus in an Intensive Care Unit

A new method for estimating the time to colonization of Methicillin-resistant Staphylococcus Aureus (MRSA) patients is developed in this paper. The time to colonization of MRSA is modelled using a Bayesian smoothing approach for the hazard function. There are two prior models discussed in this paper: the first difference prior and the second difference prior. The second difference prior model gives smoother estimates of the hazard functions and, when applied to data from an intensive care unit (ICU), clearly shows increasing hazard up to day 13, then a decreasing hazard. The results clearly demonstrate that the hazard is not constant and provide a useful quantification of the effect of length of stay on the risk of MRSA colonization which provides useful insight.