Abstract Purpose: The majority of patients with high-grade serous ovarian cancer (HGSC) develop progressive disease following primary treatment, with a five-year survival rate of ~30%. However, a subset of patients have an extraordinary response to treatment and ~15% survive more than ten years (long-term survivors). The Multidisciplinary Ovarian Cancer Outcomes Group (MOCOG) aims to uncover factors that influence long-term survival of HGSC patients. Here, we investigated the genomic and immunologic determinants of exceptional survival of this deadly disease. Experimental Design: Patient characteristics and clinical histories were evaluated to identify patients diagnosed with advanced stage (Stage IIIC/IV) and histopathologically confirmed HGSC with greater than 10-year overall survival. Whole-genome sequencing (WGS) was performed on primary tumors (median 78x coverage) and germline samples (median 39x coverage) of 55 long-term survivors. Primary tumor samples were also characterised by RNA sequencing, DNA methylation profiling and immunohistochemistry. Results: A total 38 (69%) of long-term surviving patients had residual disease following surgery, suggestive of highly chemo-sensitive disease. Most patients (41, 75%) were alive at last follow-up and 26 (47%) were progression-free. Somatic mutation burden was higher in primary tumors of long-term survivors relative to controls (316 unselected HGSC patients in The Cancer Genome Atlas). Genome-wide mutational signatures were predominantly Signature 3 (associated with homologous recombination deficiency), Signature 1 (age related) and Signatures 5, 8 and 16 (unknown etiology). Inactivation of the tumor suppressor RB1 by structural rearrangements or homozygous deletion was frequent in long-term survivors, with 33% of tumors showing associated loss of RB1 protein expression by immunohistochemistry compared to 13% of unselected HGSC controls (n=207; P = 0.001). Staining of adjacent tumor tissue revealed that RB1 loss was associated with increased numbers of PD-1+ tumor-infiltrating lymphocytes (P = 0.015) and MHC class I on tumor cells (P = 0.002). In an independent HGSC cohort (n=847), RB1 protein loss was associated with prolonged survival (HR: 0.75, P < 0.001) compared to patients with RB1 positive tumors. Furthermore, co-occurrence of germline mutations in BRCA1 or BRCA2 and RB1 loss was associated with a significantly longer overall survival compared to patients with retained RB1 protein expression and no germline BRCA mutation (HR: 0.44, P < 0.001). Conclusions: This study delineates the full landscape of genomic alterations in HGSC of long-term survivors. Our findings indicate that specific mutations might be associated with enhanced host immune responses and long-term survival. Citation Format: Dale W. Garsed, Ahwan Pandey, Sian Fereday, Kathryn Alsop, Maartje C. Wouters, Flurina Saner, Jessica A. Beach, Katy Milne, Catherine J. Kennedy, Joy Hendley, Nadia Traficante, Celeste L. Pearce, Malcolm C. Pike, Multidisciplinary Ovarian Cancer Outcomes Group, Susan J. Ramus, Martin Köbel, Brad H. Nelson, Ellen L. Goode, Anna deFazio, David D. Bowtell. The genomic landscape of high-grade serous ovarian cancer in long-term survivors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2722.
Abstract High-grade serous ovarian cancer (HGSC) was one of the first cancer types subjected to comprehensive genomic analysis, and over the last 5-7 years gene expression and DNA sequence data have been generated from hundreds of samples. A large majority of this data has been obtained from surgical samples collected following primary debulking surgery or following a few cycles of neoadjuvant chemotherapy. By contrast, comparatively little data exist from patients who have been extensively treated with chemotherapy or newer targeted agents, such as antiangiogenics or PARP inhibitors (PARPi). Of particular interest are samples collected from patients whose cancer was initially responsive to treatment but has become resistant to therapy (acquired resistance) at the time of collection. The presentation will describe data obtained from whole-genome (N=73 samples, 36 patients) and targeted (N=65 samples, 48 patients) sequence analysis of recurrent or end-stage HGSC samples, focusing in particular on two mechanisms of acquired resistance–fusions involving the ABCB1 gene and reversion of germline BRCA1/2 mutations. ABCB1 encodes the multidrug resistance transporter MDR1, also known as P-glycoprotein. Data will be presented on the frequency and mechanisms of ABCB1 deregulation in recurrent HGSC, and approaches to clinical intervention in fusion-positive patients. Reversions in BRCA1/2 appear to render tumors that were defective in homologous recombination (HR) repair, HR proficient and therefore may have important implications for likely treatment response. The presentation will also discuss approaches to evaluating reversion status in patients with mutation in BRCA1/2. Citation Format: Elizabeth L. Christie, Jessica Beach, Dariush Etemadmoghadam, Dale Garsed, Ann-Marie Patch, Sian Fereday, Swetansu Pattnaik, Australian Ovarian Cancer Study, Samuel Brady, Andrea Bild, David D.L. Bowtell. Acquired chemotherapy resistance in high-grade serous ovarian cancer patients. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr IA12.
Abstract ABCB1 encodes Multidrug Resistance protein (MDR1), an ATP-binding cassette member involved in the cellular efflux of chemotherapeutic drugs. Here we report that ovarian and breast samples from chemotherapy treated patients are positive for multiple transcriptional fusions involving ABCB1 , placing it under the control of a strong promoter while leaving its open reading frame intact. We identified 15 different transcriptional fusion partners involving ABCB1 , as well as patients with multiple distinct fusion events. The partner gene selected depended on its structure, promoter strength, and chromosomal proximity to ABCB1 . Fusion positivity was strongly associated with the number of lines of MDR1-substrate chemotherapy given. MDR1 inhibition in a fusion positive ovarian cancer cell line increased sensitivity to paclitaxel more than 50-fold. Convergent evolution of ABCB1 fusion is therefore frequent in chemotherapy resistant recurrent ovarian cancer. As most currently approved PARP inhibitors (PARPi) are MDR1 substrates, prior chemotherapy may precondition resistance to PARPi.
Abstract Suboptimal cytoreductive surgery in advanced epithelial ovarian cancer (EOC) is associated with poor survival but it is unknown if poor outcome is due to the intrinsic biology of unresectable tumors or insufficient surgical effort resulting in residual tumor-sustaining clones. Our objective was to identify the potential molecular pathway(s) and cell type(s) that may be responsible for suboptimal surgical resection. By comparing gene expression in optimally and suboptimally cytoreduced patients, we identified a gene network associated with suboptimal cytoreduction and explored the biological processes and cell types associated with this gene network. We show that primary tumors from suboptimally cytoreduced patients express molecular signatures that are typically present in a distinct molecular subtype of EOC characterized by increased stromal activation and lymphovascular invasion. Similar molecular pathways are present in EOC metastases, suggesting that primary tumors in suboptimally cytoreduced patients are biologically similar to metastatic tumors. We demonstrate that the suboptimal cytoreduction network genes are enriched in reactive tumor stroma cells rather than malignant tumor cells. Our data suggest that the success of cytoreductive surgery is dictated by tumor biology, such as extensive stromal reaction and increased invasiveness, which may hinder surgical resection and ultimately lead to poor survival. Citation Format: Zhenqiu Liu, Jessica A. Beach, Hasmik Agadjanian, Dongyu Jia, Paul-Joseph Aspuria, Beth Y. Karlan, Sandra Orsulic. Suboptimal cytoreduction in ovarian carcinoma is associated with molecular pathways characteristic of increased stromal activation. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr B64.
Succinate dehydrogenase (SDH) is a mitochondrial metabolic enzyme complex involved in both the electron transport chain and the citric acid cycle. SDH mutations resulting in enzymatic dysfunction have been found to be a predisposing factor in various hereditary cancers. Therefore, SDH has been implicated as a tumor suppressor. We identified that dysregulation of SDH components also occurs in serous ovarian cancer, particularly the SDH subunit SDHB. Targeted knockdown of Sdhb in mouse ovarian cancer cells resulted in enhanced proliferation and an epithelial-to-mesenchymal transition (EMT). Bioinformatics analysis revealed that decreased SDHB expression leads to a transcriptional upregulation of genes involved in metabolic networks affecting histone methylation. We confirmed that Sdhb knockdown leads to a hypermethylated epigenome that is sufficient to promote EMT. Metabolically, the loss of Sdhb resulted in reprogrammed carbon source utilization and mitochondrial dysfunction. This altered metabolic state of Sdhb knockdown cells rendered them hypersensitive to energy stress. These data illustrate how SDH dysfunction alters the epigenetic and metabolic landscape in ovarian cancer. By analyzing the involvement of this enzyme in transcriptional and metabolic networks, we find a metabolic Achilles' heel that can be exploited therapeutically. Analyses of this type provide an understanding how specific perturbations in cancer metabolism may lead to novel anticancer strategies.
Abstract The specific targeting of inhibitor of apoptosis (IAP) proteins by Smac-mimetic (SM) drugs, such as birinapant, has been tested in clinical trials of acute myeloid leukemia (AML) and certain solid cancers. Despite their promising safety profile, SMs have had variable and limited success. Using a library of more than 5700 bioactive compounds, we screened for approaches that could sensitize AML cells to birinapant and identified multidrug resistance protein 1 inhibitors (MDR1i) as a class of clinically approved drugs that can enhance the efficacy of SM therapy. Genetic or pharmacological inhibition of MDR1 increased intracellular levels of birinapant and sensitized AML cells from leukemia murine models, human leukemia cell lines, and primary AML samples to killing by birinapant. The combination of clinical MDR1 and IAP inhibitors was well tolerated in vivo and more effective against leukemic cells, compared with normal hematopoietic progenitors. Importantly, birinapant combined with third-generation MDR1i effectively killed murine leukemic stem cells (LSCs) and prolonged survival of AML-burdened mice, suggesting a therapeutic opportunity for AML. This study identified a drug combination strategy that, by efficiently killing LSCs, may have the potential to improve outcomes in patients with AML.
Abstract : A significant number of women with high-grade serous ovarian cancer (HGSC) are intrinsically refractory to standard platinum-based treatment. We have previously shown that amplification of the cyclin E1 gene (CCNE1) in HGSC is associated with primary chemoresistance and poor clinical outcome. Therefore, we hypothesized that cyclin E1 is a key therapeutic target in HGSC, and that generation of a genetically engineered mouse (GEM) model of CCNE1-amplified HGSC will facilitate the development of novel therapeutic strategies. Here, we have generated two mouse strains with Cre-mediated expression of full-length or truncated Ccne1 at the Rosa26 locus. We plan to cross these mice with Pax8-TetOCre-Tp53 mice in order to induce expression of Ccne1 in the fallopian tube epithelium and drive the initiation and development of HGSC. Mouse models that closely resemble human disease have been powerful platforms for new therapies and understanding resistance mechanisms. Immune checkpoint inhibitors have shown substantial activity in melanoma and lung cancer, and it is now a priority to extend these findings to other solid cancers, including HGSC. The availability of an intact animal model ofCCNE1 is likely to be a substantial value in development of immune checkpoint inhibitors and other approaches to targetingCCNE1 amplified tumours.
Background: Antimicrobial stewardship (AMS) encompasses numerous interventions that seek to improve antimicrobial usage, as inappropriate use of antimicrobials may result in the promotion of antimicrobial resistance, patient harm, and increased costs. AMS is of particular interest in intensive care units (ICUs) where antimicrobial use is extensive. Few qualitative studies have sought to identify the perceived attitudes and beliefs of intensive care clinicians around AMS. Objectives: To understand ICU nursing and physician priorities and preferences around AMS and possible AMS interventions for implementation in the ICU. Methods: Using consecutive sampling, semi-structured one-to-one interviews were conducted with ICU nursing and physician staff at a tertiary hospital in BC, Canada. Results: Nine participants (seven nurses and two physicians) were interviewed, and themes were identified and categorized as: opportunities to improve AMS in the ICU, barriers to AMS in the ICU, and possible future AMS interventions for implementation in the ICU. Opportunities identified included: clinician activities (improved communication, de-escalation, ICU nurse assessment) and support (infectious disease and antibiotic experts, AMS presence). Barriers identified included: knowledge gaps (infectious disease and antibiotic knowledge, AMS awareness), AMS and ICU integration (nursing role in AMS, AMS efficacy in ICU), and environment (competing priorities, critical care context). Interventions identified included: organisational (EMR modifications, checklists, algorithms), learning (infectious disease and antimicrobial education, audit, and feedback), and nursing intervention (antibiotic review, prompting reassessment).
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