Accrual Quality Improvement Program for clinical trials

BACKGROUND

The Early Phase Cancer Prevention Clinical Trials Program (Consortia), led by the Division of Cancer Prevention, National Cancer Institute, supports and conducts trials assessing safety, tolerability, and cancer preventive potential of a variety of interventions. Accrual to cancer prevention trials includes the recruitment of unaffected populations, posing unique challenges related to minimizing participant burden and risk, given the less evident or measurable benefits to individual participants. The Accrual Quality Improvement Program was developed to address these challenges and better understand the multiple determinants of accrual activity throughout the life of the trial. Through continuous monitoring of accrual data, Accrual Quality Improvement Program identifies positive and negative factors in real-time to optimize enrollment rates for ongoing and future trials.

METHODS

The Accrual Quality Improvement Program provides a web-based centralized infrastructure for collecting, analyzing, visualizing, and storing qualitative and quantitative participant-, site-, and study-level data. The Accrual Quality Improvement Program approaches cancer prevention clinical trial accrual as multi-factorial, recognizing protocol design, potential participants' characteristics, and individual site as well as study-wide implementation issues.

RESULTS

The Accrual Quality Improvement Program was used across 39 Consortia trials from 2014 to 2022 to collect comprehensive trial information. The Accrual Quality Improvement Program captures data at the participant level, including number of charts reviewed, potential participants contacted and reasons why participants were not eligible for contact or did not consent to the trial or start intervention. The Accrual Quality Improvement Program also captures site-level (e.g. staffing issues) and study-level (e.g. when protocol amendments are made) data at each step of the recruitment/enrollment process, from potential participant identification to contact, consent, intervention, and study completion using a Recruitment Journal. Accrual Quality Improvement Program's functionality also includes tracking and visualization of a trial's cumulative accrual rate compared to the projected accrual rate, including a zone-based performance rating with corresponding quality improvement intervention recommendations.

CONCLUSION

The challenges associated with recruitment and timely completion of early phase cancer prevention clinical trials necessitate a data collection program capable of continuous collection and quality improvement. The Accrual Quality Improvement Program collects cumulative data across National Cancer Institute, Division of Cancer Prevention early phase clinical trials, providing the opportunity for real-time review of participant-, site-, and study-level data and thereby enables responsive recruitment strategy and protocol modifications for improved recruitment rates to ongoing trials. Of note, Accrual Quality Improvement Program data collected from ongoing trials will inform future trials to optimize protocol design and maximize accrual efficiency.

Older age should not be a barrier to testing for somatic variants in homologous recombination DNA repair-related genes in patients with high-grade serous ovarian carcinoma

BACKGROUND

Somatic pathogenic variants (PVs) in homologous recombination DNA repair (HR)-related genes found in high-grade serous ovarian carcinomas (HGSC) are not well-characterised in older patients (≥70 years). This may reflect low testing rates in older patients.

METHODS

Data from 1210 HGSC patients in AACR Project GENIE and 324 patients in an independent dataset INOVATe were analysed. Cases where somatic variants could be distinguished from germline variants were included, and analysis was restricted to those with a somatic TP53 variant, to ensure cases were HGSC.

RESULTS

Of 1210 patients in GENIE, 27% (n = 325) were aged ≥70 years at testing. Patients with somatic-only PVs in BRCA2 were older compared with BRCA1 (median 71 vs 60 years, p = 0.002). Median age for 21 patients with somatic-only PVs in 11 other HR-related genes ranged from 40 to 67 years. In older patients, 7% (n = 22) had somatic BRCA1/2 PVs, and 1% (n = 2) had PVs other HR-related genes; this rate was not significantly different to younger patients (<70 years), 7% (n = 62) BRCA1/2 and 2% (n = 19) other HR-related genes (p = 0.36). The overall frequency of somatic BRCA1/2 PVs was similar in INOVATe (n = 25; 7.7%) and somatic-only BRCA2 PVs were again found in older patients compared with BRCA1 (median age: at testing, 70 vs 63 years; at diagnosis, 68 vs 60 years).

CONCLUSIONS

The overall frequency of somatic-only PVs in HR-related genes was similar in older and younger patients with HGSC, highlighting the importance of somatic testing irrespective of age. Limiting somatic testing by age may exclude patients who could benefit from maintenance poly(ADP-ribose) polymerase (PARP) inhibitors.

The Role of Statins in the Prevention of Ovarian and Endometrial Cancers

Ovarian and endometrial cancers are the most common gynecologic malignancies and emerging evidence suggests that lipid metabolism and subsequent inflammation are important etiologic factors for both tumors. Statins (HMG-CoA reductase inhibitors) are the most widely prescribed lipid-lowering drugs in the United States and are used by 25% of adults aged 40+ years. In addition to their cardio-protective actions, statins have anti-inflammatory effects and have demonstrated antiproliferative and apoptotic properties in cancer cell lines, supporting a potential role in cancer prevention. To appropriately quantify potential public health impact of statin use for cancer prevention, there is a great need to understand the potential risk reduction among individuals at a higher risk of gynecologic cancers, the group that will likely need to be targeted to effectively balance risk/benefit of medications repurposed for cancer prevention. In this commentary, we focus on summarizing emerging evidence suggesting that the anti-inflammatory and lipid-lowering mechanisms of statins may provide important cancer-preventive benefits for gynecologic cancers as well as outline important unanswered questions and future research directions.

Lessons from the Failure to Complete a Trial of Denosumab in Women With a Pathogenic BRCA1/2 Variant Scheduling Risk-Reducing Salpingo-Oophorectomy

Female carriers of pathogenic/likely pathogenic (P/LP) BRCA1/2 variants are at increased risk of developing breast and ovarian cancer. Currently, the only effective strategy for ovarian cancer risk reduction is risk-reducing bilateral salpingo-oophorectomy (RR-BSO), which carries adverse effects related to early menopause. There is ongoing investigation of inhibition of the RANK ligand (RANKL) with denosumab as a means of chemoprevention for breast cancer in carriers of BRCA1 P/LP variants. Through the NCI Division of Cancer Prevention (DCP) Early Phase Clinical Trials Prevention Consortia, a presurgical pilot study of denosumab was developed in premenopausal carriers of P/LP BRCA1/2 variants scheduled for RR-BSO with the goal of collecting valuable data on the biologic effects of denosumab on gynecologic tissue. The study was terminated early due to the inability to accrue participants. Challenges which impacted the conduct of this study included a study design with highly selective eligibility criteria and requirements and the COVID-19 pandemic. It is critical to reflect on these issues to enhance the successful completion of future prevention studies in individuals with hereditary cancer syndromes.

Cross-sectional clinical cancer genomics community of practice survey analysis of provider attitudes and beliefs regarding the use of deceased family member tissue to guide living family member genetic cancer risk assessment

Next-generation tumor tissue sequencing techniques may result in the detection of putative germline pathogenic variants (PVs), raising the possibility that germline cancer predisposition could be identified from archival medical tissue samples of deceased relatives. The approach, termed traceback, is designed to inform risk management recommendations for living family members. Provider perspectives regarding traceback testing have not yet been explored, so we conducted a cross-sectional survey of Clinical Cancer Genomics Community of Practice providers regarding their attitudes and beliefs toward traceback testing. Self-reported demographics, provider characteristics, attitudes and perceived barriers were collected. We evaluated responses in the context of whether providers had previous experience with traceback testing. Data were analyzed using chi-square and Fisher's exact testing. Among 207 respondents (of 816 eligible), most were women (89.4%), white (85.5%), and not Hispanic or Latino (89.7%). US-based providers represented the majority of respondents (87.4%). Relatively, few providers 32 of 207 (15.5%) had previous experience with traceback. Among the individuals without experience in traceback, 84.0% thought there would be barriers to implementation; however, only 68.8% of individuals with previous traceback experience agreed (p = .04). Respondents in both groups thought that traceback would be valuable in their practice (82.6%, p = .22) and that they would feel comfortable discussing the concept (83.6%, p = .83), interpreting the results (72.2%, p = .24), and discussing the results with their patients (80.7%, p = .38). Patient interest and cost were seen as less of a barrier by those with experience with traceback testing. Recurrent themes obtained in open-ended responses are also presented. Overall, providers believe that traceback would be a valuable tool in their practice. Individuals with previous experience identified less barriers with implementation of this testing, highlighting an area for future research and education.

Associations Between Intraluminal Tumor Cell Involvement in Serially Examined Fallopian Tubes and Endometrial Carcinoma Characteristics and Outcomes

Approximately 12% of routinely examined fallopian tubes of endometrial carcinoma (EC) cases have intraluminal tumor cells (ILTCs). ILTC associations with EC characteristics and outcomes are understudied, and unknown in serially examined and embedded tubal fimbriae. Glass slides of serially examined and embedded tubal fimbriae for 371 EC cases were independently reviewed by 2 pathologists who recorded ILTC presence and characterized them as mucosal if involved and floating if not. Disagreements were reviewed by a third pathologist, and agreement between any 2 determined final ILTC status. Clinico-pathologic associations and ILTC presence were tested for significance ( P <0.05) by univariable analysis, and stage and histotype determinants were included in a multivariable analysis. The Kaplan-Meier estimates and log-rank tests compared overall and EC-specific survival, and Cox proportional regression estimated hazard ratios. ILTCs were present in 56 (15.1%) cases: 30 mucosal and 26 floating. FIGO stage 3/4, lymph-vascular space invasion, deep myometrial invasion, nonendometrioid histotype, and adjunctive chemotherapy were significantly associated with ILTC presence, and only stage was significant in the multivariable analysis. Overall, 61 women died: 30 of whom died of EC. ILTCs were nonsignificantly associated with higher overall and EC-specific mortality and mucosal ILTCs had the highest hazard ratios (1.64 and 1.89, respectively). Serially examined and embedded tubal fimbriae have a higher prevalence of ILTCs than routinely examined tubes, and high FIGO stage is an independent determinant. A prognostic effect was not found, but the higher trending hazard ratios suggest additional study is needed to determine whether ILTCs and in particular mucosal ILTCs adversely affect prognosis.

Surgical window-of-opportunity study of megestrol acetate compared with megestrol acetate and metformin for endometrial intraepithelial neoplasia

TPS5601

Background: Endometrial Intraepithelial Neoplasia (EIN) is a precursor lesion to endometrial carcinoma (EC), the most common gynecologic cancer among women in the US. The current standard of care for women with EIN is hysterectomy. Non-surgical treatments are needed for women desiring fertility preservation, and for those who are medically unfit for a major surgical procedure. Progestin therapy is the cornerstone of current nonsurgical management of EIN. However, approximately 30% of patients with EIN do not respond to progestin therapy, or respond incompletely. EIN is closely related to insulin resistance and metabolic syndrome with evidence that increased insulin resistance is a significant risk factor for development of EC. Metformin, an inhibitor of insulin/PI3K/AKT pathway, has been demonstrated to reduce endometrial proliferation in vitro and in vivo. We hypothesize that the combination of metformin and progestin therapy may synergize to arrest EIN progression and prevent the development of EC. Methods: This is a randomized pre-surgical window of opportunity study, comparing a commonly used oral progestin, megestrol acetate (MA), to MA and metformin (M). Patients with pathologically confirmed EIN or complex atypical hyperplasia (CAH) who present for hysterectomy will be approached. After enrollment, participants will receive MA 80mg PO BID ± M 500mg BID for 4 ± 1 weeks pre-operatively. Post-therapy endometrial biopsy will be obtained in the operating room prior to the hysterectomy, and compared to the pre-therapy diagnostic endometrial biopsy sample. The primary endpoint is the change in the percentage (%) of Ki-67 expressing cells (%Ki-67) between the pre- and post-treatment biopsies. Based on a two-sample t-test comparing the pre- to post-treatment changes in %Ki-67 between the two arms, a sample size of 21 patients per arm achieves 80% power with two-sided α = 0.05 to detect an absolute reduction in %Ki-67 of 10% vs. 17.6% in the MA vs. MA + M arms. An interim analysis is planned after enrollment of 32 patients, and an internal pilot approach based on variance re-estimation will be used to increase the sample size if needed, to maintain the original planned power. Secondary endpoints will include comparison of changes in protein expression of ER, PR, PTEN/PAX2, markers of the PI3K/AKT/MTOR pathway, cell death and intratumoral insulin signaling. We will randomize 50 subjects at five sites: Northwestern University, Cedars-Sinai (Los Angeles), Duke University, University of Colorado, and University of North Carolina. Participants will be randomized 1:1 and stratified by menopausal status to ensure balance between the two arms. Since September 2021, four sites have opened and 22 patients have been pre-screened. Three participants were enrolled and two have completed intervention. The study is expected to complete accrual by the end of 2023. Clinical trial information: NCT04576104.

Lessons Learned from the Impact of COVID-19 on NCI-sponsored Cancer Prevention Clinical Trials: Moving Toward Participant-centric Study Designs

The COVID-19 pandemic overloaded health care systems around the globe and brought travel restrictions and other mandates. These effects critically impacted cancer care and conduct of clinical trials, and required medical and research communities to incorporate changes and novel flexible workflows within clinical trials and regulations to improve efficiency. We report the impact of the pandemic on cancer prevention clinical trials managed by the Division of Cancer Prevention within the NCI, focusing on participant-centric, study staff-centric and regulatory elements. Learning lessons from this challenging period, the cancer prevention community has the opportunity to incorporate many of these necessitated novel approaches to future design of clinical trials, to streamline and improve clinical trial efficiency and impact.

Report from an NCI Roundtable: Cancer Prevention in Primary Care

The Division of Cancer Prevention in the NCI sponsored a Roundtable with primary care providers (PCP) to determine barriers for integrating cancer prevention within primary care and discuss potential opportunities to overcome these barriers. The goals were to: (i) assess the cancer risk assessment tools available to PCPs; (ii) gather information on use of cancer prevention resources; and (iii) understand the needs of PCPs to facilitate the implementation of cancer prevention interventions beyond routine screening and interventions. The Roundtable discussion focused on challenges and potential research opportunities related to: (i) cancer risk assessment and management of high-risk individuals; (ii) cancer prevention interventions for risk reduction; (iii) electronic health records/electronic medical records; and (iv) patient engagement and information dissemination. Time constraints and inconsistent/evolving clinical guidelines are major barriers to effective implementation of cancer prevention within primary care. Social determinants of health are important factors that influence patients' adoption of recommended preventive interventions. Research is needed to determine the best means for implementation of cancer prevention across various communities and clinical settings. Additional studies are needed to develop tools that can help providers collect clinical data that can enable them to assess patients' cancer risk and implement appropriate preventive interventions.

Report of the National Cancer Institute and the Eunice Kennedy Shriver National Institute of Child Health and Human Development-sponsored workshop: gynecology and women's health-benign conditions and cancer

The Division of Cancer Prevention and the Division of Cancer Biology at the National Cancer Institute and the Gynecologic Health and Disease Branch in the National Institute of Child Health and Human Development organized a workshop in April 2019 to explore current insights into the progression of gynecologic cancers from benign conditions. Working groups were formed based on 3 gynecologic disease types: (1) Endometriosis or Endometrial Cancer and Endometrial-Associated Ovarian Cancer, (2) Uterine Fibroids (Leiomyoma) or Leiomyosarcoma, and (3) Adenomyosis or Adenocarcinoma. In this report, we highlight the key questions and current challenges that emerged from the working group discussions and present potential research opportunities that may advance our understanding of the progression of gynecologic benign conditions to cancer.

Assessment of and Interventions for Women at High Risk for Breast or Ovarian Cancer: A Survey of Primary Care Physicians

As clinical guidelines for cancer prevention refer individuals to primary care physicians (PCP) for risk assessment and clinical management, PCPs may be expected to play an increasing role in cancer prevention. It is crucial that PCPs are adequately supported to assess an individual's cancer risk and make appropriate recommendations. The objective of this study is to assess use, familiarity, attitude, and behaviors of PCPs regarding breast and ovarian cancer risk and prevention, to better understand the factors that influence their prescribing behaviors. We conducted a cross-sectional, web-based survey of PCPs in the United States, recruited from an opt-in healthcare provider panel. Invitations were sent in batches until the target sample size of 750 respondents (250 each for obstetrics/gynecology, internal medicine, and family medicine) was met. Self-reported use of breast/ovarian cancer risk assessments was low (34.7%-59.2%) compared with discussion of cancer family history (96.9%), breast exams (87.1%), and mammograms (92.8%). Although most respondents (48.0%-66.8%) were familiar with cancer prevention interventions, respondents who reported to be less familiar were more likely to report cautious attitudes. When presented with hypothetical cases depicting patients at different breast/ovarian cancer risks, up to 34.0% of respondents did not select any of the clinically recommended course(s) of action. This survey suggests that PCP use of breast/ovarian cancer risk assessment tools and ability to translate the perceived risks to clinical actions is variable. Improving implementation of cancer risk assessment and clinical management guidelines within primary care may be necessary to improve the appropriate prescribing of cancer prevention interventions.Prevention Relevance: Primary care physicians are becoming more involved in cancer prevention management, so it is important that cancer risk assessment and medical society guideline recommendations for cancer prevention are better integrated into primary care to improve appropriate prescribing of cancer prevention interventions and help reduce cancer risk.

Proteogenomic analysis of Inhibitor of Differentiation 4 (ID4) in basal-like breast cancer

BACKGROUND

Basal-like breast cancer (BLBC) is a poorly characterised, heterogeneous disease. Patients are diagnosed with aggressive, high-grade tumours and often relapse with chemotherapy resistance. Detailed understanding of the molecular underpinnings of this disease is essential to the development of personalised therapeutic strategies. Inhibitor of differentiation 4 (ID4) is a helix-loop-helix transcriptional regulator required for mammary gland development. ID4 is overexpressed in a subset of BLBC patients, associating with a stem-like poor prognosis phenotype, and is necessary for the growth of cell line models of BLBC through unknown mechanisms.

METHODS

Here, we have defined unique molecular insights into the function of ID4 in BLBC and the related disease high-grade serous ovarian cancer (HGSOC), by combining RIME proteomic analysis, ChIP-seq mapping of genomic binding sites and RNA-seq.

RESULTS

These studies reveal novel interactions with DNA damage response proteins, in particular, mediator of DNA damage checkpoint protein 1 (MDC1). Through MDC1, ID4 interacts with other DNA repair proteins (γH2AX and BRCA1) at fragile chromatin sites. ID4 does not affect transcription at these sites, instead binding to chromatin following DNA damage. Analysis of clinical samples demonstrates that ID4 is amplified and overexpressed at a higher frequency in BRCA1-mutant BLBC compared with sporadic BLBC, providing genetic evidence for an interaction between ID4 and DNA damage repair deficiency.

CONCLUSIONS

These data link the interactions of ID4 with MDC1 to DNA damage repair in the aetiology of BLBC and HGSOC.

Cancer Prevention in Primary Care: Perception of Importance, Recognition of Risk Factors and Prescribing Behaviors

PURPOSE

Acceptability and uptake of cancer preventive interventions is associated with physician recommendation, which is dependent on physician familiarity with available preventive options. The goal of this study is to evaluate cancer prevention perceptions, understanding of breast and ovarian cancer risk factors, and prescribing behaviors of primary care physicians.

METHODS

We conducted cross-sectional. Web-based survey of 750 primary care physicians (250 each for obstetrics/gynecology, internal medicine, and family medicine) in the United States. Survey respondents were recruited from an opt-in health care provider panel.

RESULTS

Perception of importance and the practice of recommending general and cancer-specific preventive screenings and interventions significantly differed by provider type. These perceptions and behaviors reflected the demographics of the population that the primary care physicians see within their respective practices. The majority of respondents recognized genetic/hereditary risk factors for breast or ovarian cancer, while epidemiologic or clinical risk factors were less frequently recognized. Prescribing behaviors were related to familiarity with the interventions, with physicians indicating that they more frequently reinforced a specialist's recommendation rather than prescribed a preventive intervention.

CONCLUSIONS

Cancer prevention perceptions, recognition of cancer risk factors, and prescribing behaviors differ among practice types and were related to familiarity with preventive options. Cancer prevention education and risk assessment resources should be more widely available to primary care physicians.

Expression of long noncoding RNAs in cancer-associated fibroblasts linked to patient survival in ovarian cancer

Cancer-associated fibroblasts (CAFs) are the most abundant cell type in the tumor microenvironment and are responsible for producing the desmoplastic reaction that is a poor prognostic factor in ovarian cancer. Long non-coding RNAs (lncRNAs) have been shown to play important roles in cancer. However, very little is known about the role of lncRNAs in the tumor microenvironment. We aimed to identify lncRNAs expressed in ovarian CAFs that were associated with patient survival and used computational approaches to predict their function. Increased expression of 9 lncRNAs and decreased expression of 1 lncRNA in ovarian CAFs were found to be associated with poorer overall survival. A "guilt-by-association" approach was used to predict the function of these lncRNAs. In particular, MIR155HG was predicted to play a role in immune response. Further investigation revealed high MIR155HG expression to be associated with higher infiltrates of immune cell subsets. In conclusion, these data indicate expression on several lncRNAs in CAFs are associated with patient survival and are likely to play an important role in regulating CAF function.

Abstract TMIM-067: EXPRESSION OF LNCRNAS IN OVARIAN CANCER-ASSOCIATED FIBROBLASTS IS ASSOCIATED WITH PATIENT SURVIVAL

BACKGROUND: Ovarian cancer is the most lethal gynecological malignancy in women, with high-grade serous ovarian cancer (HGSOC) the most common and aggressive subtype. The tumor microenvironment is acknowledged to play a vital role in the growth and metastasis of many solid tumors, including ovarian cancer, and as such represents an attractive new therapeutic target. In ovarian cancer, patients with a higher proportion of desmoplasia have a poorer survival. Cancer-associated fibroblasts (CAFs) represent the most abundant cell type in the tumor stroma and are responsible for producing the desmoplastic reaction that is a poor prognostic factor in HGSOC. Genetic aberrations in ovarian CAFs are extremely rare, raising the possibility of alternative mechanisms that regulate gene expression in CAFs, such as regulation by long non-coding RNAs (lncRNAs). LncRNAs are transcripts that do not encode for protein, but have been shown to play important roles in several diseases, including cancer. However, very little is known about the role of lncRNAs in the tumor microenvironment.

OBJECTIVES: To identify lncRNAs whose expression levels in CAFs are associated with patient survival and use computational approaches to predict their function.

METHODS: CAFs were laser capture microdissected from 67 advanced stage HGSOCs. RNA was extracted from the microdissected samples and expression analyzed using Affymetrix U133 Plus 2.0 Arrays. Probes identified as lncRNAs were used in this analysis. Samples were normalized and background corrected using the robust multiarray average (RMA) method and expression values were log2 transformed. Expression levels of each lncRNA were clustered into low and high expression groups. Kaplan Meier /log-rank analysis was used to assess the association between expression levels of each lncRNA and the patients' overall survival. Multivariate cox regression analysis was used to determine if differential expression of lncRNAs were independent predictors of survival. A network based ‘guilt-by-association' approach was used to predict the function of lncRNAs associated with patient survival.

RESULTS: Increased expression of 9 lncRNAs including DANCR, MALAT1 and NEAT1 and decreased expression of 1 lncRNA in ovarian CAFs were found to be associated with poorer overall survival by the log-rank test. Expression profiles of 5 lncRNAs as well as response to chemotherapy and debulking status were significant predictors of survival by univariate cox proportional hazards analysis. To adjust for existing collinearity of the 10 lncRNAs, the first principal component of these lncRNAs (capturing 98% of variations), as well as response to chemotherapy and debulking status were incorporated into a multivariate model. The first principal component (HR=0.74, P=0.0001163) and response to chemotherapy (HR=0.22, P=0.000168) were found to be independent predictors of survival. Functional enrichment analysis revealed these lncRNAs are likely to play a role in metabolism, autophagy or immune response.

CONCLUSIONS: We have identified several lncRNAs whose expression levels in CAFs are associated with survival of HGSOC patients, raising the likelihood that they play an important role in the tumor-promoting functions of CAFs. A further understanding of the role of lncRNAs in CAFs may be useful when designing novel therapies that target the tumor microenvironment.

Citation Format: Emily K. Colvin, Viive M. Howell, Samuel C. Mok, Goli Samimi and Fatemeh Vafaee. EXPRESSION OF LNCRNAS IN OVARIAN CANCER-ASSOCIATED FIBROBLASTS IS ASSOCIATED WITH PATIENT SURVIVAL [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr TMIM-067.

The molecular origin and taxonomy of mucinous ovarian carcinoma

Mucinous ovarian carcinoma (MOC) is a unique subtype of ovarian cancer with an uncertain etiology, including whether it genuinely arises at the ovary or is metastatic disease from other organs. In addition, the molecular drivers of invasive progression, high-grade and metastatic disease are poorly defined. We perform genetic analysis of MOC across all histological grades, including benign and borderline mucinous ovarian tumors, and compare these to tumors from other potential extra-ovarian sites of origin. Here we show that MOC is distinct from tumors from other sites and supports a progressive model of evolution from borderline precursors to high-grade invasive MOC. Key drivers of progression identified are TP53 mutation and copy number aberrations, including a notable amplicon on 9p13. High copy number aberration burden is associated with worse prognosis in MOC. Our data conclusively demonstrate that MOC arise from benign and borderline precursors at the ovary and are not extra-ovarian metastases.

Acceptability of Localized Cancer Risk Reduction Interventions Among Individuals at Average or High Risk for Cancer

Individuals at high risk for cancer, including those already diagnosed with premalignant lesions, can potentially benefit from chemopreventive interventions to reduce cancer risk. However, uptake and acceptability have been hindered due to the risk of systemic toxicity and other adverse effects. Locally delivered chemopreventive agents, where direct action on the primary organ may limit systemic toxicity, are emerging as an option for high-risk individuals. While a number of clinical trials support the development of chemopreventive agents, it is crucial to understand the factors and barriers that influence their acceptability and use. We conducted 36 focus groups with 198 individuals at average and high risk of breast/ovarian, gynecologic, and head/neck/oral and lung cancers to examine the perceptions and acceptability of chemopreventive agents. Participants' willingness to use chemopreventive agents was influenced by several factors, including perceived risk of cancer, skepticism around prevention, previous knowledge of chemopreventive agents, support from trusted sources of health information, participation in other cancer-related risk-reduction activities, previous experience with similar modalities, cost, regimen, side effects, and perceived effectiveness of the preventive intervention. Our findings indicate that individuals may be more receptive to locally delivered chemopreventive agents if they perceive themselves to be at high risk for cancer and are given the necessary information regarding regimen and side effects to make an informed decision. Clinical trials that collect additional patient-centered data including side effects and how these interventions fit into an individual's lifestyle are imperative to improve uptake of chemopreventive agents.

Abstract OT2-09-01: Pilot study of denosumab in BRCA1/2 mutation carriers scheduling for risk-reducing salpingo-oophorectomy

Background: Denosumab is a monoclonal antibody that inhibits RANKL and is approved for the prevention of fractures in patients with osteoporosis or bone metastases. The RANKL signaling pathway is also involved in BRCA1-associated mammary tumorigenesis via a progesterone-induced paracrine effect of RANKL on luminal progenitor cells. Pre-clinical studies have demonstrated that RANKL inhibition resulted in reduced proliferation of mammary tumors. Early findings from an ongoing pre-surgical study demonstrated that denosumab treatment resulted in decreased Ki67 proliferation index in benign breast tissue. Based on these data, denosumab is being pursued as a potential preventive agent for breast cancer in BRCA1 mutation carriers. While promising, the effect of RANKL inhibition on gynecologic tissues such as the ovaries and fallopian tubes, in which progesterone has a protective effect, is unknown.

Trial design: We will conduct a multicenter, open-label randomized pilot study of presurgical administration of denosumab versus no treatment in premenopausal women with BRCA1/2 mutations undergoing risk-reducing salpingo-oophorectomy (RRSO). A total of 60 women will be randomized 1:1 to Arm 1) 3-4 doses of 120 mg denosumab subcutaneously every 4 weeks or Arm 2) No treatment. Participants will be stratified by 1) BRCA1 versus BRCA2 mutation status and 2) Use of hormonal contraceptives within the past 3 months (yes/no). Assuming a 10% unevaluable rate, we expect to have 54 evaluable participants (27 per arm).

Eligibility criteria: 1) Premenopausal women (defined as &lt; 3 months since last menstrual period OR serum follicle-stimulating hormone (FSH) &lt; 20 mIU/mL), age &gt; 18 years; 2) Documented germline pathogenic mutation or likely pathogenic variant in the BRCA1 or BRCA2 gene; 3) Plan for RRSO with or without hysterectomy; 4) ECOG performance status ≤ 1 (Karnofsky ≥ 70%); 5) Normal organ and marrow function; 6) Negative pregnancy test and use of adequate contraception; 7) Willingness to take supplemental oral calcium and vitamin D3; 8) Dental examination within 6 months of enrollment and no evidence of active dental issues; 9) Ability to understand and willingness to provide informed consent.

Specific aims: Our primary objective is to compare the effect of denosumab to no treatment on Ki67 expression in the fimbrial end of the fallopian tube. Secondary objectives are to assess Ki67 in ovary and endometrium; cleaved caspase-3, RANK/RANKL, ER/PR, CD44, and STAT3/pSTAT3 expression in fallopian tube, ovary, and endometrium; gene expression profiling in the fallopian tube and ovary; serum markers (progesterone, estradiol, C-terminal telopeptide) and denosumab levels; and toxicity.

Statistical methods: The primary endpoint is post-treatment Ki67 expression in the fimbrial end of the fallopian tube in the denosumab arm compared to the no treatment arm. Assuming a standard deviation of 5.0%, we will have 82% power to detect a 4.0% absolute difference (or effect size of 0.8) in Ki67 proliferation index between the denosumab and no treatment groups by applying a 2-sample t-test at a 0.05 significance level.

Target accrual: 60 participants, to be activated in Summer 2018.

Citation Format: Trivedi MS, Samimi G, Wright JD, Holcomb K, Garber JE, Horowitz NS, Arber N, Friedman E, Wenham RM, House M, Parnes H, Lee JJ, Abutaseh S, Vornik LA, Heckman-Stoddard BM, Brown PH, Crew KD. Pilot study of denosumab in BRCA1/2 mutation carriers scheduling for risk-reducing salpingo-oophorectomy [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT2-09-01.

Population Frequency of Serous Tubal Intraepithelial Carcinoma (STIC) in Clinical Practice Using SEE-Fim Protocol

Frequent detection of serous tubal intraepithelial carcinoma (STIC) among BRCA1/2 mutation carriers undergoing risk-reducing surgery prompted the hypothesis that many adnexal high-grade serous carcinomas (HGSCs) arise from the fallopian tube, rather than the ovary, as supposed. The changing paradigm has important implications for HGSC prevention. Most data related to the frequency of STIC are derived from case series and estimates vary widely. Therefore, we analyzed population-based data from 10 523 surgeries including salpingectomy (Jan 2014-Dec 2016) that were examined using the "Sectioning and Extensively Examining the Fimbria" protocol, which optimizes STIC detection. Overall, STIC was detected in 40 (0.38%) specimens, including 32 diagnosed with concurrent gynecologic cancer. STIC was detected in 8 (<0.01%) of 9392 cases with benign diagnoses. We conclude that the relative rarity of STIC diagnoses in routine pathology practice has critical implications for research aiming to elucidate the pathogenesis of HGSC and developing prevention strategies.

Processing of fallopian tube, ovary, and endometrial surgical pathology specimens: A survey of U.S. laboratory practices

OBJECTIVE

Many high-grade serous carcinomas initiate in fallopian tubes as serous tubal intraepithelial carcinoma (STIC), a microscopic lesion identified with specimen processing according to the Sectioning and Extensive Examination of the Fimbria protocol (SEE-Fim). Given that the tubal origin of these cancers was recently recognized, we conducted a survey of pathology practices to assess processing protocols that are applied to gynecologic surgical pathology specimens in clinical contexts in which finding STIC might have different implications.

METHODS

We distributed a survey electronically to the American Society for Clinical Pathology list-serve to determine practice patterns and compared results between practice types by chi-square (χ2) tests for categorical variables. Free text comments were qualitatively reviewed.

RESULTS

Survey responses were received from 159 laboratories (72 academic, 87 non-academic), which reported diverse specimen volumes and percentage of gynecologic samples. Overall, 74.1% of laboratories reported performing SEE-Fim for risk-reducing surgical specimens (82.5% academic versus 65.7% non-academic, p < 0.05). In specimens from surgery for benign indications in which initial microscopic sections showed an unanticipated suspicious finding, 75.9% of laboratories reported using SEE-Fim to process the remainder of the specimen (94.8% academic versus 76.4% non-academic, p < 0.01), and 84.6% submitted the entire fimbriae.

CONCLUSIONS

Changes in the theories of pathogenesis of high-grade serous carcinoma have led to implementation of pathology specimen processing protocols that include detailed analysis of the fallopian tubes. These results have implications for interpreting trends in cancer incidence data and considering the feasibility of developing a bank of gynecologic tissues containing STIC or early cancer precursors.

Ovarian cancer statistics, 2018

In 2018, there will be approximately 22,240 new cases of ovarian cancer diagnosed and 14,070 ovarian cancer deaths in the United States. Herein, the American Cancer Society provides an overview of ovarian cancer occurrence based on incidence data from nationwide population-based cancer registries and mortality data from the National Center for Health Statistics. The status of early detection strategies is also reviewed. In the United States, the overall ovarian cancer incidence rate declined from 1985 (16.6 per 100,000) to 2014 (11.8 per 100,000) by 29% and the mortality rate declined between 1976 (10.0 per 100,000) and 2015 (6.7 per 100,000) by 33%. Ovarian cancer encompasses a heterogenous group of malignancies that vary in etiology, molecular biology, and numerous other characteristics. Ninety percent of ovarian cancers are epithelial, the most common being serous carcinoma, for which incidence is highest in non-Hispanic whites (NHWs) (5.2 per 100,000) and lowest in non-Hispanic blacks (NHBs) and Asians/Pacific Islanders (APIs) (3.4 per 100,000). Notably, however, APIs have the highest incidence of endometrioid and clear cell carcinomas, which occur at younger ages and help explain comparable epithelial cancer incidence for APIs and NHWs younger than 55 years. Most serous carcinomas are diagnosed at stage III (51%) or IV (29%), for which the 5-year cause-specific survival for patients diagnosed during 2007 through 2013 was 42% and 26%, respectively. For all stages of epithelial cancer combined, 5-year survival is highest in APIs (57%) and lowest in NHBs (35%), who have the lowest survival for almost every stage of diagnosis across cancer subtypes. Moreover, survival has plateaued in NHBs for decades despite increasing in NHWs, from 40% for cases diagnosed during 1992 through 1994 to 47% during 2007 through 2013. Progress in reducing ovarian cancer incidence and mortality can be accelerated by reducing racial disparities and furthering knowledge of etiology and tumorigenesis to facilitate strategies for prevention and early detection. CA Cancer J Clin 2018;68:284-296. © 2018 American Cancer Society.

Transducin-Like Enhancer of Split 3 (TLE3) Expression Is Associated with Taxane Sensitivity in Nonserous Ovarian Carcinoma in a Three-Cohort Study

Background: Chemoresistance is a major challenge in ovarian cancer treatment, resulting in poor survival rates. Identifying markers of treatment response is imperative for improving outcome while minimizing unnecessary side effects. We have previously demonstrated that expression of transducin-like enhancer of split 3 (TLE3) is associated with favorable progression-free survival in taxane-treated ovarian cancer patients with nonserous histology. The purpose of this study was to perform an independent evaluation of the association of TLE3 expression with response to taxane-based chemotherapy in nonserous ovarian cancer, to validate its role as a potential therapeutic response marker for taxane-based chemotherapy.Methods: We performed immunohistochemical staining of TLE3 on ovarian cancer specimens from the Australian Ovarian Cancer Study, the Westmead Gynaecological Oncology Biobank, and Memorial Sloan Kettering Cancer Center. Progression-free survival and overall survival were assessed to validate an association between TLE3 expression and response to taxane therapy that we previously observed in a smaller study.Results: Expression of TLE3 was associated with favorable outcome only in patients who had received paclitaxel as part of their treatment regimen for both 3-year progression-free survival (n = 160; HR, 0.56; P = 0.03) and 5-year overall survival (HR, 0.53; P = 0.04). Further analysis revealed that the predictive association between TLE3 expression and outcome was strongest in tumors with clear cell histology.Conclusions: The association between high TLE3 expression and a favorable response to taxane-containing chemotherapy regimens was validated in patients with nonserous ovarian cancer.Impact: TLE3 expression may serve as a marker of chemosensitivity in taxane-treated patients with nonserous histologies. Cancer Epidemiol Biomarkers Prev; 27(6); 680-8. ©2018 AACR.

Estimating the number of potential family members eligible for BRCA1 and BRCA2 mutation testing in a "Traceback" approach

U.S. guidelines recommend BRCA1/2 mutation testing for women diagnosed with high-grade ovarian cancer (HGOC) to increase recognition of carriers, but most remain unidentified and at risk. Accordingly, an approach termed "Traceback" has been proposed in which probands are retrospectively identified by testing archived pathology specimens, and family members are traced to provide genetic counseling and testing. We used population-based data to estimate the number of family members who might be contacted through such a program. We used incidence data from the Surveillance, Epidemiology, and End Results (SEER) Program to estimate the number of women diagnosed with HGOC from 2005 to 2016, and census data to estimate the number of spouses, offspring, and siblings (both sexes). Using overall survival for HGOC from SEER and all-cause mortality rates from the Centers for Diseases Control and Prevention, we estimated the number of patients, spouses, offspring, and siblings of HGOC cases living in 2017. Due to the high mortality rate of HGOC, consent from living probands may be possible in only 42% of the cases; consent to test pathology specimens would need to be sought from next of kin for the remainder. In 2017, an estimated 406,919 living next of kin (spouses, siblings, offspring) would be available for potential consent. Testing archived ovarian cancer pathology specimens may enable the identification of BRCA1/2 mutation carriers, but consent from next of kin would be required in in 58% of cases. Although Traceback offers the possibility of identifying unaffected BRCA1/2 mutation carriers, pilot feasibility studies that include assessment of methods to secure consent are needed.

Ovarian Cancer Prevention in High-risk Women

Ovarian carcinoma is the most lethal malignancy of the female genital tract. Population-based trials in the general population have not demonstrated that screening improves early detection or survival. Therefore, application of prevention strategies is vital to improving outcomes from this disease. Surgical prevention reduces risk and prophylactic risk-reducing salpingo-oophorectomy is the most effective means to prevent ovarian carcinoma in the high-risk patient although the risks do not outweigh the benefits in average risk patients. Other surgical and medical options have unknown or limited efficacy in the high-risk patient. In this review, we define the patient at high risk for ovarian cancer, discuss how to identify these women and weigh their available ovarian cancer prevention strategies.

Outcomes from ovarian cancer screening in the PLCO trial: Histologic heterogeneity impacts detection, overdiagnosis and survival

AIM

A mortality benefit from screening for ovarian cancer has never been demonstrated. The aim of this study was to evaluate the screening outcomes for different histologic subtypes of ovarian cancers.

METHODS

Women in the screening arm of the Prostate, Lung, Colorectal and Ovarian Screening Trial underwent CA-125 and transvaginal ultrasound annually for 3-5 years. We compared screening test characteristics (including overdiagnosis) and outcomes by tumour type (type II versus other) and study arm (screening versus usual care).

RESULTS

Of 78,215 women randomised, 496 women were diagnosed with ovarian cancer. Of the tumours that were characterised (n = 413; 83%), 74% (n = 305) were type II versus 26% other (n = 108). Among screened patients, 70% of tumours were type II compared to 78% in usual care (p = 0.09). Within the screening arm, 29% of type II tumours were screen detected compared to 54% of the others (p < 0.01). The sensitivity of screening was 65% for type II tumours versus 86% for other types (p = 0.02). 15% of type II screen-detected tumours were stage I/II, compared to 81% of other tumours (p < 0.01). The overdiagnosis rate was lower for type II compared to other tumours (28.2% versus 72.2%; p < 0.01). Ovarian cancer-specific survival was worse for type II tumours compared to others (p < 0.01). Survival was similar for type II (p = 0.74) or other types (p = 0.32) regardless of study arm.

CONCLUSIONS

Test characteristics of screening for ovarian cancer differed for type II tumours compared to other ovarian tumours. Type II tumours were less likely to be screen diagnosed, early stage at diagnosis or overdiagnosed.

Functional prediction of long non-coding RNAs in ovarian cancer-associated fibroblasts indicate a potential role in metastasis

Cancer-associated fibroblasts (CAFs) contribute to the poor prognosis of ovarian cancer. Unlike in tumour cells, DNA mutations are rare in CAFs, raising the likelihood of other mechanisms that regulate gene expression such as long non-coding RNAs (lncRNAs). We aimed to identify lncRNAs that contribute to the tumour-promoting phenotype of CAFs. RNA expression from 67 ovarian CAF samples and 10 normal ovarian fibroblast (NOF) samples were analysed to identify differentially expressed lncRNAs and a functional network was constructed to predict those CAF-specific lncRNAs involved in metastasis. Of the 1,970 lncRNAs available for analysis on the gene expression array used, 39 unique lncRNAs were identified as differentially expressed in CAFs versus NOFs. The predictive power of differentially expressed lncRNAs in distinguishing CAFs from NOFs were assessed using multiple multivariate models. Interrogation of known transcription factor-lncRNA interactions, transcription factor-gene interactions and construction of a context-specific interaction network identified multiple lncRNAs predicted to play a role in metastasis. We have identified novel lncRNAs in ovarian cancer that are differentially expressed in CAFs compared to NOFs and are predicted to contribute to the metastasis-promoting phenotype of CAFs.

A re-analysis of the prostate, lung, colorectal, and ovarian (PLCO) cancer screening trial accounting for ovarian cancer (OVCA) heterogeneity

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Background: A mortality benefit from screening for OVCA has not been demonstrated, but screening efficacy could differ for histologic subtypes. We re-analyzed PLCO evaluating whether OVCA detection and outcomes were affected by the heterogeneous biologic behavior of this disease. Methods: Type 2 tumors (moderately/poorly differentiated serous and adenocarcinoma) were compared to all other tumor (OT) types (low grade serous and endometrioid, clear cell, other, low malignancy potential) (LMP). We examined differences in the distribution of tumor types and stage by study arm and method of diagnosis [screen detected (SD) and interval detected (ID) (i.e. assigned to screening but diagnosed between screening tests)]. Stage distribution and survival were analyzed. Results: Among the entire PLCO population, 531 women were diagnosed with OVCA during the study; 282 (53%) in the screening arm and 249 (47%) in the usual care arm. Of the tumors able to be characterized (n=408; 77%), 74% (n=300) were Type 2 and 26% OT (n=108). In the screening arm, 70% of tumors diagnosed were Type 2 compared to 78% in usual care (p=0.07). Overall, survival was significantly better for OT tumors compared to Type 2 tumors (p<0.01) but there was no difference in survival by study arm for either tumor type separately (Type 2: p=0.50; OT: p=0.23). Within the screening arm, 30% of Type 2 tumors were SD compared to 54% of OT tumors (p=0.02) (see Table). Only 15% of Type 2 SD tumors were Stage I/II, compared to 82% of SD OT tumors (p<0.01). Stage at diagnosis was similar among Type 2 patients whether they were SD or ID (p=0.56) and there was no difference in survival (p=0.56). Conclusions: A significant difference in tumor types by study arm was not observed. However, within the screening arm, Type 2 tumors were less likely to be SD or Stage I/II compared to OT tumors. Survival for Type 2 tumors was similar regardless of method of diagnosis. [Table: see text]

Traceback: A Proposed Framework to Increase Identification and Genetic Counseling of BRCA1 and BRCA2 Mutation Carriers Through Family-Based Outreach

In May 2016, the Division of Cancer Prevention and the Division of Cancer Control and Population Sciences, National Cancer Institute, convened a workshop to discuss a conceptual framework for identifying and genetically testing previously diagnosed but unreferred patients with ovarian cancer and other unrecognized BRCA1 or BRCA2 mutation carriers to improve the detection of families at risk for breast or ovarian cancer. The concept, designated Traceback, was prompted by the recognition that although BRCA1 and BRCA2 mutations are frequent in women with ovarian cancer, many such women have not been tested, especially if their diagnosis predated changes in testing guidelines. The failure to identify mutation carriers among probands represents a lost opportunity to prevent cancer in unsuspecting relatives through risk-reduction intervention in mutation carriers and to provide appropriate reassurances to noncarriers. The Traceback program could provide an important opportunity to reach families from racial, ethnic, and socioeconomic groups who historically have not sought or been offered genetic counseling and testing and thereby contribute to a reduction in health disparities in women with germline BRCA mutations. To achieve an interdisciplinary perspective, the workshop assembled international experts in genetics, medical and gynecologic oncology, clinical psychology, epidemiology, genomics, cost-effectiveness modeling, pathology, bioethics, and patient advocacy to identify factors to consider when undertaking a Traceback program. This report highlights the workshop deliberations with the goal of stimulating research and providing a framework for pilot studies to assess the feasibility and ethical and logistical considerations related to the development of best practices for implementation of Traceback studies.

Connective tissue growth factor as a novel therapeutic target in high grade serous ovarian cancer

Ovarian cancer is the most common cause of death among women with gynecologic cancer. We examined molecular profiles of fibroblasts from normal ovary and high-grade serous ovarian tumors to identify novel therapeutic targets involved in tumor progression. We identified 2,300 genes that are significantly differentially expressed in tumor-associated fibroblasts. Fibroblast expression of one of these genes, connective tissue growth factor (CTGF), was confirmed by immunohistochemistry. CTGF protein expression in ovarian tumor fibroblasts significantly correlated with gene expression levels. CTGF is a secreted component of the tumor microenvironment and is being pursued as a therapeutic target in pancreatic cancer. We examined its effect in in vitro and ex vivo ovarian cancer models, and examined associations between CTGF expression and clinico-pathologic characteristics in patients. CTGF promotes migration and peritoneal adhesion of ovarian cancer cells. These effects are abrogated by FG-3019, a human monoclonal antibody against CTGF, currently under clinical investigation as a therapeutic agent. Immunohistochemical analyses of high-grade serous ovarian tumors reveal that the highest level of tumor stromal CTGF expression was correlated with the poorest prognosis. Our findings identify CTGF as a promoter of peritoneal adhesion, likely to mediate metastasis, and a potential therapeutic target in high-grade serous ovarian cancer. These results warrant further studies into the therapeutic efficacy of FG-3019 in high-grade serous ovarian cancer.

Rationale for Developing a Specimen Bank to Study the Pathogenesis of High-Grade Serous Carcinoma: A Review of the Evidence

Women with clinically detected high-grade serous carcinomas (HGSC) generally present with advanced-stage disease, which portends a poor prognosis, despite extensive surgery and intensive chemotherapy. Historically, HGSCs were presumed to arise from the ovarian surface epithelium (OSE), but the inability to identify early-stage HGSCs and their putative precursors in the ovary dimmed prospects for advancing our knowledge of the pathogenesis of these tumors and translating these findings into effective prevention strategies. Over the last decade, increased BRCA1/2 mutation testing coupled with performance of risk-reducing surgeries has enabled studies that have provided strong evidence that many, but probably not all, HGSCs among BRCA1/2 mutation carriers appear to arise from the fallopian tubes, rather than from the ovaries. This shift in our understanding of the pathogenesis of HGSCs provides an important opportunity to achieve practice changing advances; however, the scarcity of clinically annotated tissues containing early lesions, particularly among women at average risk, poses challenges to progress. Accordingly, we review studies that have kindled our evolving understanding of the pathogenesis of HGSC and present the rationale for developing an epidemiologically annotated national specimen resource to support this research. Cancer Prev Res; 9(9); 713-20. ©2016 AACR.

Methylated circulating tumor DNA in blood: power in cancer prognosis and response

Circulating tumor DNA (ctDNA) in the plasma or serum of cancer patients provides an opportunity for non-invasive sampling of tumor DNA. This 'liquid biopsy' allows for interrogations of DNA such as quantity, chromosomal alterations, sequence mutations and epigenetic changes, and can be used to guide and improve treatment throughout the course of the disease. This tremendous potential for real-time 'tracking' in a cancer patient has led to substantial research efforts in the ctDNA field. ctDNA can be distinguished from non-tumor DNA by the presence of tumor-specific mutations and copy number variations, and also by aberrant DNA methylation, with both DNA sequence and methylation changes corresponding to those found in the tumor. Aberrant methylation of specific promoter regions can be a very consistent feature of cancer, in contrast to mutations, which typically occur at a wide range of sites. This consistency makes ctDNA methylation amenable to the design of widely applicable clinical assays. In this review, we examine ctDNA methylation in the context of monitoring disease status, treatment response and determining the prognosis of cancer patients.

INC280, an orally available small molecule inhibitor of c-MET, reduces migration and adhesion in ovarian cancer cell models

5-year survival rates for ovarian cancer are approximately 40%, and for women diagnosed at late stage (the majority), just 27%. This indicates a dire need for new treatments to improve survival rates. Recent molecular characterization has greatly improved our understanding of the disease and allowed the identification of potential new targets. One such pathway of interest is the HGF/c-MET axis. Activation of the HGF/c-MET axis has been demonstrated in certain ovarian tumours, and been found to be associated with decreased overall survival, suggesting its potential as a therapeutic target. The objective of this study was to determine the efficacy of a novel, highly potent, orally-bioavailable c-MET inhibitor, INC280, in blocking cell phenotypes important in ovarian cancer metastasis. Using in vitro and ex vivo models, we demonstrate that INC280 inhibits HGF-induced c-MET, and reduces downstream signalling. HGF-stimulated chemotactic and random migration are decreased by INC280 treatment, to levels seen in non-stimulated cells. Additionally, HGF-induced adhesion of cancer cells to peritoneal tissue is significantly decreased by INC280 treatment. Overall, these data indicate that INC280 inhibits many cell behaviours that promote ovarian cancer metastasis, and merits further investigation as a therapeutic candidate in the treatment of patients with ovarian cancer.

Methylation of cell-free circulating DNA in the diagnosis of cancer

A range of molecular alterations found in tumor cells, such as DNA mutations and DNA methylation, is reflected in cell-free circulating DNA (circDNA) released from the tumor into the blood, thereby making circDNA an ideal candidate for the basis of a blood-based cancer diagnosis test. In many cancer types, mutations driving tumor development and progression are present in a wide range of oncogenes and tumor suppressor genes. However, even when a gene is consistently mutated in a particular cancer, the mutations can be spread over very large regions of its sequence, making evaluation difficult. This diversity of sequence changes in tumor DNA presents a challenge for the development of blood tests based on DNA mutations for cancer diagnosis. Unlike mutations, DNA methylation that can be consistently measured, as it tends to occur in specific regions of the DNA called CpG islands. Since DNA methylation is reflected within circDNA, detection of tumor-specific DNA methylation in patient plasma is a feasible approach for the development of a blood-based test. Aberrant circDNA methylation has been described in most cancer types and is actively being investigated for clinical applications. A commercial blood test for colorectal cancer based on the methylation of the SEPT9 promoter region in circDNA is under review for approval by the Federal Drug Administration (FDA) for clinical use. In this paper, we review the state of research in circDNA methylation as an application for blood-based diagnostic tests in colorectal, breast, lung, pancreatic and ovarian cancers, and we consider some of the future directions and challenges in this field. There are a number of potential circDNA biomarkers currently under investigation, and experience with SEPT9 shows that the time to clinical translation can be relatively rapid, supporting the promise of circDNA as a biomarker.

Methylation-capture and Next-Generation Sequencing of free circulating DNA from human plasma

BACKGROUND

Free circulating DNA (fcDNA) has many potential clinical applications, due to the non-invasive way in which it is collected. However, because of the low concentration of fcDNA in blood, genome-wide analysis carries many technical challenges that must be overcome before fcDNA studies can reach their full potential. There are currently no definitive standards for fcDNA collection, processing and whole-genome sequencing. We report novel detailed methodology for the capture of high-quality methylated fcDNA, library preparation and downstream genome-wide Next-Generation Sequencing. We also describe the effects of sample storage, processing and scaling on fcDNA recovery and quality.

RESULTS

Use of serum versus plasma, and storage of blood prior to separation resulted in genomic DNA contamination, likely due to leukocyte lysis. Methylated fcDNA fragments were isolated from 5 donors using a methyl-binding protein-based protocol and appear as a discrete band of ~180 bases. This discrete band allows minimal sample loss at the size restriction step in library preparation for Next-Generation Sequencing, allowing for high-quality sequencing from minimal amounts of fcDNA. Following sequencing, we obtained 37 × 10(6)-86 × 10(6) unique mappable reads, representing more than 50% of total mappable reads. The methylation status of 9 genomic regions as determined by DNA capture and sequencing was independently validated by clonal bisulphite sequencing.

CONCLUSIONS

Our optimized methods provide high-quality methylated fcDNA suitable for whole-genome sequencing, and allow good library complexity and accurate sequencing, despite using less than half of the recommended minimum input DNA.

ZNF300P1 encodes a lincRNA that regulates cell polarity and is epigenetically silenced in type II epithelial ovarian cancer

Background

We previously identified that the CpG island-associated promoter of the novel lincRNA ZNF300P1 (also known as LOC134466) is frequently hypermethylated and silenced in ovarian cancer tissues. However, the function of ZNF300P1 was unknown. In this report we demonstrate that ZNF300P1 is involved in the regulation of key cell cycle and cell motility networks in human ovarian surface epithelial cells, and may play a role in promoting metastasis in ovarian cancer cells.

Methods

We applied methylated DNA immunoprecipitation on whole genome promoter tiling arrays and Sequenom assays to examine methylation status of ZNF300P1 in multiple ovarian cancer cell lines, as well as in normal ovarian and ovarian tumor tissues. Transcript profiling was used to investigate the effects of ZNF300P1 suppression in ovarian cancer cells. We utilized siRNA knockdown in normal ovarian surface epithelial cells and performed cellular proliferation, migration and adhesion assays to validate and explore the profiling results.

Results

We demonstrate that ZNF300P1 is methylated in multiple ovarian cancer cell lines. Loss of ZNF300P1 results in decreased cell proliferation and colony formation. In addition, knockdown of the ZNF300P1 transcript results in aberrant and less persistent migration in wound healing assays due to a loss of cellular polarity. Using an ex vivo peritoneal adhesion assay, we also reveal a role for ZNF300P1 in the attachment of ovarian cancer cells to peritoneal membranes, indicating a potential function of ZNF300P1 expression in metastasis of ovarian cancer cells to sites within the peritoneal cavity.

Conclusion

Our findings further support ZNF300P1 as frequently methylated in ovarian cancer and reveal a novel function for ZNF300P1 lincRNA expression in regulating cell polarity, motility, and adhesion and loss of expression may contribute to the metastatic potential of ovarian cancer cells.

Patient-derived xenograft models to improve targeted therapy in epithelial ovarian cancer treatment

Despite increasing evidence that precision therapy targeted to the molecular drivers of a cancer has the potential to improve clinical outcomes, high-grade epithelial ovarian cancer (OC) patients are currently treated without consideration of molecular phenotype, and predictive biomarkers that could better inform treatment remain unknown. Delivery of precision therapy requires improved integration of laboratory-based models and cutting-edge clinical research, with pre-clinical models predicting patient subsets that will benefit from a particular targeted therapeutic. Patient-derived xenografts (PDXs) are renewable tumor models engrafted in mice, generated from fresh human tumors without prior in vitro exposure. PDX models allow an invaluable assessment of tumor evolution and adaptive response to therapy. PDX models have been applied to pre-clinical drug testing and biomarker identification in a number of cancers including ovarian, pancreatic, breast, and prostate cancers. These models have been shown to be biologically stable and accurately reflect the patient tumor with regards to histopathology, gene expression, genetic mutations, and therapeutic response. However, pre-clinical analyses of molecularly annotated PDX models derived from high-grade serous ovarian cancer (HG-SOC) remain limited. In vivo response to conventional and/or targeted therapeutics has only been described for very small numbers of individual HG-SOC PDX in conjunction with sparse molecular annotation and patient outcome data. Recently, two consecutive panels of epithelial OC PDX correlate in vivo platinum response with molecular aberrations and source patient clinical outcomes. These studies underpin the value of PDX models to better direct chemotherapy and predict response to targeted therapy. Tumor heterogeneity, before and following treatment, as well as the importance of multiple molecular aberrations per individual tumor underscore some of the important issues addressed in PDX models.

Abstract A4: Whole genome sequencing of free circulating DNA from plasma of HGSOC patients

Genomic analysis of free circulating DNA (fcDNA) has a number of potential clinical applications, including cancer studies. Tumor-derived fcDNA harbors the same molecular aberrations, including mutations and methylation, as the derivative tumor. As it can be collected by non-invasive means, fcDNA is particularly promising as a cancer detection tool. In addition, molecular characterization of fcDNA in cancer patients is holds promise for determining tumor sub-types and monitoring response to treatment. However, because fcDNA concentrations are relatively low in the circulation, whole-genome analysis for molecular characterization is quite challenging. Standardization of fcDNA collection and processing for downstream analysis is imperative to help address these challenges.

Our studies focus on the development of an early detection test for high-grade serous ovarian cancer (HGSOC), using whole-genome methylation analysis in fcDNA from HGSOC patients. DNA methylation plays a key role in the development of many cancer types, and thus carries great potential as a cancer diagnostic biomarker. We propose that DNA methylation changes in HGSOC tumors can be detected in the patient's fcDNA and can be used as a blood-based test to detect HGSOC. We have carried out Next Generation Sequencing (NGS) of methylation-enriched fcDNA from 3 HGSOC patients and 5 healthy controls with the aim of identifying a list of differentially methylated loci in fcDNA that can distinguish between HGSOC and control plasma.

We also sought to generate standard protocols for collection and processing of fcDNA for whole-genome studies. First we analyzed effects of blood storage time on fcDNA recovery and quality and determined that storage for ≥8 hrs prior to plasma separation leads to increased DNA concentrations, as well as an appearance of a band that co-migrates with high-molecular weight genomic DNA. This increased DNA concentration likely represents genomic DNA contamination as a result of leukocytes lysis during storage.

We next analyzed the effects of processing and scaling on enriched fcDNA recovery and quality. We used a methyl-binding protein-based (MBD2) protocol to enrich for methylated sequences in fcDNA isolated from plasma samples. Following application of a modified protocol due to low concentrations of fcDNA in plasma, we obtained a 10.2-14.9% enrichment of methylated fragments. In preparing the sample libraries for NGS, the predominant fcDNA size of ~180 base pairs allows minimal sample loss during the size restriction step. NGS analysis provided 37-86x10^6 unique mappable reads per fcDNA sample, representing &gt;50% of the total mappable reads. These read counts indicate a satisfactory level of library complexity was achieved from minimal fcDNA input.

Our standardization protocols provide the ability to comprehensively sequence patient fcDNA using half of the recommended sample input. This optimized approach allows in-depth whole genome characterization and comparison of fcDNA isolated from HGSOC and healthy controls to develop diagnostic tools and investigate biological mechanisms driving tumor progression.

Citation Format: Kristina Warton, Lin Vita, Nicola J. Armstrong, Warren Kaplan, Kevin Ying, Helena Mangs, Neville F. Hacker, Robert L. Sutherland, Susan J. Clark, Goli Samimi. Whole genome sequencing of free circulating DNA from plasma of HGSOC patients. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr A4.

Abstract B58: Connective tissue growth factor (CTGF) as a novel therapeutic target in high grade serous ovarian cancer

The tumor microenvironment plays an active role in promoting proliferation, invasion and metastasis, thereby making soluble factors secreted by cancer-associated fibroblasts promising therapeutic targets. As a result, secreted tumor stromal factors are increasingly being targeted by newly developed anti-cancer therapies. To identify such stromal factors in ovarian cancer, we performed gene expression profiling on microdissected fibroblasts from normal ovary and from high-grade, late stage serous ovarian tumors. We identified a signature of TGFb-regulated genes, over-expressed in cancer-associated fibroblasts, which encode for secreted factors that may serve as potential therapeutic targets. One of these genes, connective tissue growth factor (CTGF), is a secreted protein that promotes proliferation, motility and extracellular matrix production in a number of cancer types. CTGF is currently being pursued as a therapeutic target by FibroGen Inc., who has developed a therapeutic anti-CTGF monoclonal antibody FG-3019. FG-3019 is currently under clinical investigation in pancreatic cancer and fibrotic diseases. To determine the role of CTGF and its potential as a therapeutic target in high-grade serous ovarian cancer (HGSOC), we examined its effect on tumor promotion in ovarian cancer cell lines and associations between CTGF expression and clinico-pathologic characteristics in HGSOC patients.

We performed functional studies in SKOV3 and OVCAR3 cell lines using recombinant protein, demonstrating that CTGF promotes anchorage-independent proliferation and migration. These effects of CTGF are blocked by FG-3019. During cancer progression, HGSOC cells from the ovary disseminate and adhere throughout the peritoneal cavity, posing a major challenge in treatment. We and others have shown that mesothelial cells in peritoneal tissue, peritoneal fibroblasts and ovarian cancer omental metastases express CTGF, suggesting that it may be targeted to help prevent recurrence following debulking surgery. To address this, we performed ex-vivo peritoneal adhesion assays, and demonstrate that recombinant CTGF increases a5b1 integrin-mediated adhesion of ovarian cancer cells to peritoneal tissue. In addition, enhancement of peritoneal adhesion by CTGF was blocked upon addition of FG-3019, further supporting its potential as a therapeutic target. In investigating clinico-pathologic characteristics in HGSOC patients, we confirmed over-expression of CTGF in cancer-associated fibroblasts by immunohistochemistry. Furthermore, we found that survival was correlated with CTGF expression, with HGSOC patients expressing the highest levels of tumor stromal CTGF harboring the poorest prognosis.

Together, our findings identify and characterize CTGF as a promoter of peritoneal adhesion, likely to mediate metastasis, and a potential therapeutic target in HGSOC. Further studies should investigate the therapeutic efficacy of FG-3019 in combination with platinum/taxane, in HGSOC.

Citation Format: Kim Moran-Jones, Rajmohan Murali, David K. Chang, Carol W. Wong, Suzanne M. Spong, Neville F. Hacker, Samuel C. Mok, Michael J. Birrer, Goli Samimi. Connective tissue growth factor (CTGF) as a novel therapeutic target in high grade serous ovarian cancer. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr B58.

TGF-β modulates ovarian cancer invasion by upregulating CAF-derived versican in the tumor microenvironment

TGF-β has limited effects on ovarian cancer cells, but its contributions to ovarian tumor growth might be mediated through elements of the tumor microenvironment. In the present study, we tested the hypothesis that TGF modulates ovarian cancer progression by modulating the contribution of cancer-associated fibroblasts (CAF) that are present in the microenvironment. Transcriptome profiling of microdissected stromal and epithelial components of high-grade serous ovarian tumors and TGF-β-treated normal ovarian fibroblasts identified versican (VCAN) as a key upregulated target gene in CAFs. Functional evaluations in coculture experiments showed that TGF-β enhanced the aggressiveness of ovarian cancer cells by upregulating VCAN in CAFs. VCAN expression was regulated in CAFs through TGF-β receptor type II and SMAD signaling. Upregulated VCAN promoted the motility and invasion of ovarian cancer cells by activating the NF-κB signaling pathway and by upregulating expression of CD44, matrix metalloproteinase-9, and the hyaluronan-mediated motility receptor. Our work identified a TGF-β-inducible gene signature specific to CAFs in advanced high-grade serous ovarian tumors, and showed how TGF-β stimulates ovarian cancer cell motility and invasion by upregulating the CAF-specific gene VCAN. These findings suggest insights to develop or refine strategies for TGF-β-targeted therapy of ovarian cancer.

TLE3 expression is associated with sensitivity to taxane treatment in ovarian carcinoma

BACKGROUND

We have previously shown that transducin-like enhancer of split 3 (TLE3) is associated with outcome specifically in patients with taxane-treated breast cancer and not in patients treated with anthracycline-based regimens without a taxane. The purpose of this study was to assess the association between TLE3 expression and recurrence in patients with ovarian carcinoma treated with a taxane containing regimen as opposed to those treated with a platinum-based agent alone.

METHODS

We carried out immunohistochemical staining of TLE3 in two series of ovarian cancer specimens from the University of Alabama at Birmingham, Birmingham, AL and the Royal Hospital for Women, Sydney, Australia. Local and distant recurrences within the first five years of follow-up were analyzed using Kaplan-Meier, Cox proportional hazard, and multivariate analysis to assess an association between TLE3 expression and response to therapy.

RESULTS

TLE3 was expressed in approximately 30% of tumors and expression was associated with a favorable outcome only in patients who had received taxane as part of their treatment regimen (n = 173, HR = 0.62, P = 0.012; P(interaction) = 0.024). Further analysis revealed that the predictive association between TLE3 expression and outcome was strongest in patients with nonserous histology.

CONCLUSION

High TLE3 expression predicts a favorable response to taxane containing chemotherapy regimens in ovarian carcinoma.

IMPACT

Our findings warrant an independent evaluation of TLE3 as a potential therapeutic response marker for taxane-based chemotherapy in ovarian cancer.

Prognostic and diagnostic significance of DNA methylation patterns in high grade serous ovarian cancer

OBJECTIVE

Altered DNA methylation patterns hold promise as cancer biomarkers. In this study we selected a panel of genes which are commonly methylated in a variety of cancers to evaluate their potential application as biomarkers for prognosis and diagnosis in high grade serous ovarian carcinoma (HGSOC); the most common and lethal subtype of ovarian cancer.

METHODS

The methylation patterns of 10 genes (BRCA1, EN1, DLEC1, HOXA9, RASSF1A, GATA4, GATA5, HSULF1, CDH1, SFN) were examined and compared in a cohort of 80 primary HGSOC and 12 benign ovarian surface epithelium (OSE) samples using methylation-specific headloop suppression PCR.

RESULTS

The genes were variably methylated in primary HGSOC, with HOXA9 methylation observed in 95% of cases. Most genes were rarely methylated in benign OSE, with the exception of SFN which was methylated in all HGSOC and benign OSE samples examined. Methylation of DLEC1 was associated with disease recurrence, independent of tumor stage and suboptimal surgical debulking (HR 3.5 (95% CI:1.10-11.07), p=0.033). A combination of the methylation status of HOXA9 and EN1 could discriminate HGSOC from benign OSE with a sensitivity of 98.8% and a specificity of 91.7%, which increased to 100% sensitivity with no loss of specificity when pre-operative CA125 levels were also incorporated.

CONCLUSIONS

This study provides further evidence to support the feasibility of detecting altered DNA methylation patterns as a potential diagnostic and prognostic approach for HGSOC.

Abstract 509: The CTGF antibody FG-3019 blocks CTGF-stimulated migration in ovarian cancer cells

Ovarian tumors generally arise from the surface epithelium of the ovary, and require interactions with host stroma to promote tumor cell proliferation and expansion. The signaling mechanisms between tumor-associated stroma and adjacent ovarian epithelial tumor cells remain unclear. We have previously analyzed gene expression profiles of laser-capture microdissected stromal cells from normal ovary and ovarian tumors and have demonstrated that normal ovarian stroma undergoes significant gene expression changes in response to the epithelial tumor microenvironment. Connective Tissue Growth Factor (CTGF), a TGF-β-regulated gene, was identified as specifically up-regulated in tumor-associated versus normal stroma. CTGF is a component of the tumor microenvironment with a demonstrated role in tumor progression and metastasis. FG-3019, a fully human monoclonal antibody against CTGF, is currently under clinical investigation in pancreatic cancer. The aim of this current study was to further elucidate the role of CTGF in ovarian cancer and examine its potential as a therapeutic target. We demonstrate that normal ovarian fibroblasts and ovarian cancer-associated fibroblasts treated with TGF-β secreted high levels of CTGF, whereas ovarian cancer epithelial cells secreted significantly lower levels. We next assessed the paracrine effect of CTGF on three different ovarian cancer cell lines, A224, OVCAR3, and SKOV3. Expression of endogenous CTGF is low in these cells which is consistent with the level found in primary ovarian tumor cells. Addition of recombinant CTGF for 6-hr stimulated migration of A224 (443 ± 20.5 vs. 85 ± 24.4 cells), OVCAR3 (104 ± 11.7 vs. 68 ± 30.1 cells) and SKOV3 (334 ± 45.6 vs. 82 ± 16.6 cells) in a transwell migration assay. Addition of the CTGF-blocking antibody FG-3019 significantly inhibited transwell migration in the presence of recombinant CTGF in all three cell lines (from 443 ± 20.5 to 197 ± 65.4 cells in A224, 334 ± 45.6 to 119 ± 29.0 cells in SKOV3 and 104 ± 11.7 to 36 ± 2.5 cells in OVCAR3). However, recombinant CTGF did not promote proliferation of these cell lines. We demonstrate that CTGF may contribute to ovarian tumor biology and that its function can be blocked by FG-3019, thus determining CTGF as a potential therapeutic target in ovarian tumors.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 509. doi:10.1158/1538-7445.AM2011-509

A gene signature predictive for outcome in advanced ovarian cancer identifies a survival factor: microfibril-associated glycoprotein 2

Advanced stage papillary serous tumors of the ovary are responsible for the majority of ovarian cancer deaths, yet the molecular determinants modulating patient survival are poorly characterized. Here, we identify and validate a prognostic gene expression signature correlating with survival in a series of microdissected serous ovarian tumors. Independent evaluation confirmed the association of a prognostic gene microfibril-associated glycoprotein 2 (MAGP2) with poor prognosis, whereas in vitro mechanistic analyses demonstrated its ability to prolong tumor cell survival and stimulate endothelial cell motility and survival via the alpha(V)beta(3) integrin receptor. Increased MAGP2 expression correlated with microvessel density suggesting a proangiogenic role in vivo. Thus, MAGP2 may serve as a survival-associated target.

Measures of energy balance and mammographic density in the Nurses' Health Study

Mammographic density is a strong risk factor for breast cancer; however the mechanism that underlies this association is unclear. We hypothesized that measures of energy balance early in life and in adulthood may be associated with mammographic density. We conducted a cross-sectional analysis of 1,398 women in the Nurses' Health Study to examine associations between physical activity, childhood and current body fatness, weight gain from age 18 years to present and mammographic density. Percent mammographic density was measured from digitized mammograms by a computer-assisted method. Demographic and lifestyle data were obtained from prospectively collected questionnaires. For all analyses, subjects were stratified into three groups: premenopausal women, postmenopausal women not currently taking hormones, and postmenopausal women currently taking hormones. Childhood body fatness was inversely associated with mammographic density. The correlations ranged from -0.15 to -0.19 in the three strata of women (P<or=0.001). The difference in mean percent mammographic density between the leanest and heaviest body types ranged from 6.2 to 9.9%. Similarly, adult body fatness was inversely associated with percent mammographic density. The correlations ranged from -0.41 to -0.48 in the three strata of women (P<0.0001). The difference in mean percent mammographic density between the leanest and heaviest body types ranged from 22.3 to 35.1%. Weight gain from age 18 was also inversely associated with mammographic density. There was no association between recent physical activity and mammographic density. These findings indicate that childhood and adult body fatness and weight change from age 18 are inversely associated with mammographic density.

A stromal-associated gene expression signature predicting for survival in a series of patients with advanced high-grade serous ovarian cancer

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Background: Prognostic gene expression signatures have been derived for undissected serous ovarian epithelial tumors, yet the specific contribution of stromal cells to patient survival has not been addressed. The aim of this study is to identify stromal genes impacting patient survival in the context of serous ovarian cancer. Methods: Expression profiling utilizing Affymetrix U133 Plus 2.0 oligonucleotide arrays was completed for 50 microdissected stromal samples derived from high-grade, late-stage serous tumors displaying a broad spectrum of survival endpoints. A semi-supervised dimension reduction method employing multivariate Cox regression and principal components analysis was applied to the expression data to identify genes associated with patient survival and establish a predictive model. qRT-PCR was employed to validate the microarray expression data. Results: Cox regression analysis identified 267 significant genes. The first 6 principal components of these genes, representing >65% of total variance, entered a multivariate Cox model through which the relative hazard of future patients can be predicted. To confirm our finding, the microarray data underwent leave-one-out validation. The patients were equally divided into low- and high-risk groups and non-parametric Kaplan-Meier analysis and log rank test demonstrated the two groups were significantly different in survival (p = 0.0115). Genes associated with cell survival and migration were identified in the prognostic signature. For validation, qRT-PCR data for all 50 specimens was correlated with microarray expression values for a series of select prognostic genes. Conculsions: In this study, we characterized and validated a stromal dervied prognostic signature associated with poor patient survival. Contained in this novel predictor may be stromal targets suitable for the design of new therapeutic interventions, or use as independent diagnostic markers.

No significant financial relationships to disclose.

Novel mechanisms of platinum drug resistance identified in cells selected for resistance to JM118 the active metabolite of satraplatin

PURPOSE

The goal of this study was to identify molecular determinants of sensitivity and resistance to JM118, the active metabolite of satraplatin, an orally bioavailable cisplatin analog that has activity in prostate cancer.

EXPERIMENTAL DESIGN

Human ovarian carcinoma 2008/JM118 cells were derived from parental 2008 cells by repeated exposure to JM118; the revertant 2008/JM118/REV subline was isolated from the 2008/JM118 cells by growth in the absence of drug. Drug sensitivity was determined by clonogenic assay and Pt levels were measured by ICP-MS.

RESULTS

Eight sequential rounds of selection yielded the 2008/JM118 subline that was 4.9-fold resistant to JM118 and cross-resistant at varying levels to satraplatin, cisplatin, carboplatin, and oxaliplatin. Cross-resistance to the other Pt drugs was lost as resistance to JM118 waned. The same parental 2008 cells selected for resistance to cisplatin were partially cross-resistant to JM118. The 2008/JM118 cells accumulated significantly more Pt than the 2008 cells when exposed to low concentrations of either JM118 or cisplatin indicating a detoxification process that involves intracellular sequestration. In contrast, 2008 cells selected for cisplatin resistance accumulated less cisplatin and less JM118 reflecting a mechanism involving reduced accumulation. The 2008 and 2008/JM118 cells did not differ in their uptake or efflux of 64Cu, expression of Cu efflux transporters ATP7A or ATP7B or their glutathione content. The 2008/JM118 cells exhibited 3.0-7.7-fold hypersensitivity to docetaxel, paclitaxel and doxorubicin. Expression profiling identified 4 genes that were significantly up-regulated and 19 that were down-regulated in the 2008/JM118 cells at a false discovery rate of 1 gene.

CONCLUSIONS

While the cellular defense mechanisms that protect cells against JM118 also mediate resistance to the other Pt drugs, these mechanisms are quite different from those commonly found in cells selected for resistance to cisplatin. JM118-resistant cells accumulate more rather than less Pt and rely on an intracellular detoxification mechanism different from that involved in cisplatin resistance. This is consistent with clinical evidence suggesting that satraplatin has activity in diseases in which cisplatin does not. In this model, JM118 resistance is associated with substantial collateral hypersensitivity to docetaxel, paclitaxel, and doxorubicin.