CA9, CYFIP2 and LGALS3BP-A Novel Biomarker Panel to Aid Prognostication in Glioma

Brain cancer is a devastating and life-changing disease. Biomarkers are becoming increasingly important in addressing clinical issues, including in monitoring tumour progression and assessing survival and treatment response. The goal of this study was to identify prognostic biomarkers associated with glioma progression. Discovery proteomic analysis was performed on a small cohort of astrocytomas that were diagnosed as low-grade and recurred at a higher grade. Six proteins were chosen to be validated further in a larger cohort. Three proteins, CA9, CYFIP2, and LGALS3BP, were found to be associated with glioma progression and, in univariate analysis, could be used as prognostic markers. However, according to the results of multivariate analysis, these did not remain significant. These three proteins were then combined into a three-protein panel. This panel had a specificity and sensitivity of 0.7459 for distinguishing between long and short survival. In silico data confirmed the prognostic significance of this panel.

An Examination of the Anti-Cancer Properties of Plant Cannabinoids in Preclinical Models of Mesothelioma

Simple Summary

Mesothelioma is a deadly disease with few treatment options. Phytocannabinoids derived from the cannabis plant are garnering interest for their anti-cancer properties, however very little is known about their effects in mesothelioma. We aimed to assess whether phytocannabinoids have anti-cancer effects in mesothelioma and potential modes of action. We showed that several phytocannabinoids inhibited growth of mesothelioma cells, with two phytocannabinoids, cannabidiol (CBD) and cannabigerol (CBG), being the most potent. CBD and CBG also inhibited mesothelioma cell migration and invasion. Gene expression analysis highlighted signalling pathways that play a role in how CBD and CBG may exert their anti-cancer effects. CBD and CBG were unable to increase survival in a rat model of mesothelioma but this may be due to limitations in the drug delivery method.

Abstract

Mesothelioma is an aggressive cancer with limited treatment options and a poor prognosis. Phytocannabinoids possess anti-tumour and palliative properties in multiple cancers, however their effects in mesothelioma are unknown. We investigated the anti-cancer effects and potential mechanisms of action for several phytocannabinoids in mesothelioma cell lines. A panel of 13 phytocannabinoids inhibited growth of human (MSTO and H2452) and rat (II-45) mesothelioma cells in vitro, and cannabidiol (CBD) and cannabigerol (CBG) were the most potent compounds. Treatment with CBD or CBG resulted in G0/G1 arrest, delayed entry into S phase and induced apoptosis. CBD and CBG also significantly reduced mesothelioma cell migration and invasion. These effects were supported by changes in the expression of genes associated with the cell cycle, proliferation, and cell movement following CBD or CBG treatment. Gene expression levels of CNR1, GPR55, and 5HT1A also increased with CBD or CBG treatment. However, treatment with CBD or CBG in a syngeneic orthotopic rat mesothelioma model was unable to increase survival. Our data show that cannabinoids have anti-cancer effects on mesothelioma cells in vitro and alternatives of drug delivery may be needed to enhance their effects in vivo.

Differential effects of radiation fractionation regimens on glioblastoma

BACKGROUND

Radiotherapy (RT) is a mainstay of treatment for patients with glioblastoma (GB). Early clinical trials show that short course hypofractionation showed no survival benefit compared to conventional regimens with or without temozolomide chemotherapy (TMZ) but reduces the number of doses required. Concerns around delayed neurological deficits and reduced cognition from short course hypofractionated RT remain a concern. The aim of this study was to evaluate the effect of increased interfractional time using two different radiation fractionation regimens on GB.

METHODS

The radiobiological effect of increasing doses 0-20 Gy x-ray photon RT on Gl261 and CT2A GB cell lines was compared by colony forming assay, DNA damage by alkaline comet assay, oxidative stress, DNA damage, cell cycle, and caspase-3/7 by MUSE® flow cytometric analyses, and protein expression by western blot analyses. Conventional (20 Gy/10 fractions) and hypofractionated (20 Gy/4 fractions spaced 72 h apart) RT regimens with and without TMZ (200 mg/kg/day) were performed in syngeneic Gl261 and CT2A intracranial mouse models using the Small Animal Radiation Research Platform (Xstrahl Inc.).

RESULTS

X-ray photon radiation dose-dependently increased reactive oxygen species, DNA damage, autophagy, and caspase 3/7-mediated apoptotic cell death. While the conventional fractionated dose regimen of 20 Gy/10 f was effective at inducing cell death via the above mechanism, this was exceeded by a 20 Gy/4 f regimen which improved median survival and histopathology in Gl261-tumor bearing mice, and eradicated tumors in CT2A tumors with no additional toxicity.

CONCLUSIONS

Spacing of hypofractionated RT doses 72 h apart showed increased median survival and tumor control via increased activation of RT-mediated cell death, with no observed increased in radiotoxicity. This supports further exploration of differential RT fractionated regimens in GB clinical trials to reduce delayed neurological radiotoxicity.

Optimal Upfront Treatment in Surgically Resectable Pancreatic Cancer Candidates: A High-Volume Center Retrospective Analysis

Pancreatic adenocarcinoma is a devastating disease with only 15-20% of patients resectable at diagnosis. Neoadjuvant chemotherapy for this cohort is becoming increasingly popular; however, there are no published randomized trials that support the use of neoadjuvant chemotherapy over upfront surgery in resectable disease. This retrospective cohort analysis was conducted to compare both treatment pathways and to identify any potential prognostic markers. Medical records from one large volume pancreatic cancer center from 2013-2019 were reviewed and 126 patients with upfront resectable disease were analyzed. Due to a change in practice in our center patients treated prior to December 2016 received upfront surgery and those treated after this date received neoadjuvant chemotherapy. Of these, 86 (68%) patients were treated with upfront surgery and 40 (32%) of patients were treated with neoadjuvant chemotherapy. Our results demonstrated that patients treated with upfront surgery with early-stage (1a) disease had a longer median OS compared to those treated with neoadjuvant chemotherapy (24 vs. 21 months, p = 0.028). This survival difference was not evident for all patients (regardless of stage). R0 resections were similar between groups (p = 0.605). We identified that both tumor viability (in neoadjuvant chemotherapy-treated patients) and tumor grade were useful prognostic markers. Upfront surgery for certain patients with low volume disease may be suitable despite the global trend towards neoadjuvant chemotherapy for all upfront resectable patients. A prospective clinical trial in this cohort incorporating biomarkers is needed to determine optimal therapy pathway.

Glycolysis and Fatty Acid Oxidation Inhibition Improves Survival in Glioblastoma

Glioblastoma (GBM) is the most aggressive adult glioma with a median survival of 14 months. While standard treatments (safe maximal resection, radiation, and temozolomide chemotherapy) have increased the median survival in favorable O(6)-methylguanine-DNA methyltransferase (MGMT)-methylated GBM (~21 months), a large proportion of patients experience a highly debilitating and rapidly fatal disease. This study examined GBM cellular energetic pathways and blockade using repurposed drugs: the glycolytic inhibitor, namely dicholoroacetate (DCA), and the partial fatty acid oxidation (FAO) inhibitor, namely ranolazine (Rano). Gene expression data show that GBM subtypes have similar glucose and FAO pathways, and GBM tumors have significant upregulation of enzymes in both pathways, compared to normal brain tissue (p < 0.01). DCA and the DCA/Rano combination showed reduced colony-forming activity of GBM and increased oxidative stress, DNA damage, autophagy, and apoptosis in vitro. In the orthotopic Gl261 and CT2A syngeneic murine models of GBM, DCA, Rano, and DCA/Rano increased median survival and induced focal tumor necrosis and hemorrhage. In conclusion, dual targeting of glycolytic and FAO metabolic pathways provides a viable treatment that warrants further investigation concurrently or as an adjuvant to standard chemoradiation for GBM.

Overlooked potential of positrons in cancer therapy

Positron (β⁺) emitting radionuclides have been used for positron emission tomography (PET) imaging in diagnostic medicine since its development in the 1950s. Development of a fluorinated glucose analog, fluorodeoxyglucose, labelled with a β⁺ emitter fluorine-18 (¹⁸F-FDG), made it possible to image cellular targets with high glycolytic metabolism. These targets include cancer cells based on increased aerobic metabolism due to the Warburg effect, and thus, ¹⁸F-FDG is a staple in nuclear medicine clinics globally. However, due to its attention in the diagnostic setting, the therapeutic potential of β⁺ emitters have been overlooked in cancer medicine. Here we show the first in vitro evidence of β⁺ emitter cytotoxicity on prostate cancer cell line LNCaP C4-2B when treated with 20 Gy of ¹⁸F. Monte Carlo simulation revealed thermalized positrons (sub-keV) traversing DNA can be lethal due to highly localized energy deposition during the thermalization and annihilation processes. The computed single and double strand breakages were ~ 55% and 117% respectively, when compared to electrons at 400 eV. Our in vitro and in silico data imply an unexplored therapeutic potential for β⁺ emitters. These results may also have implications for emerging cancer theranostic strategies, where β⁺ emitting radionuclides could be utilized as a therapeutic as well as a diagnostic agent once the challenges in radiation safety and protection after patient administration of a radioactive compound are overcome.

ALK-Rearranged Non-Small Cell Lung Cancer in 2020: Real-World Triumphs in an Era of Multigeneration ALK-Inhibitor Sequencing Informed by Drug Resistance Profiling

Since its discovery in 2007, we have seen the lives of patients diagnosed with advanced anaplastic lymphoma kinase (ALK)-rearranged non-small cell lung cancers (NSCLC) transform with the advent of molecular therapies with first-, second-, and third-generation ALK inhibitors now available in the clinic. Despite great gains in patient survival now measured in years and preserved quality of life with targeted therapies, drug resistance is unfortunately inevitably encountered in this rare and unique molecular subset of lung cancer, and patients will eventually succumb to the disease. As these patients are often young, fit, and never smokers, the clinical and scientific communities have aligned to expedite drug development and access. Drug resistance profiling and further strategies are being explored through clinical trials, including the evaluation of specific drug sequencing and combinations to overcome such resistance and promote patient longevity. The cases of this report focus on precision medicine and aim to portray the pertinent aspects to consider when treating ALK-rearranged NSCLC in 2020, an ever-shifting space. By way of case examples, this report offers valuable information to the treating clinician, including the evolution of systemic treatments and the management of oligo-progression and multisite drug resistance. With the maturation of real-world data, we are fortunate to be experiencing quality and length of life for patients with this disease surpassing prior expectations in advanced lung cancer. KEY POINTS: This report focuses on the importance of genetic analysis of serial biopsies to capture the dynamic therapeutic vulnerabilities of a patient's tumor, providing a perspective on the complexity of ALK tyrosine kinase inhibitor (ALKi) treatment sequencing. These case examples contribute to the literature on ALK-rearranged and oncogene addicted non-small cell lung cancer (NSCLC), providing a framework for care in the clinic. In oligo-progressive disease, local ablative therapy and continuation of ALKi postprogression should be considered with potential for sustained disease control. ALK G1202R kinase domain mutations (KDM), highly prevalent at resistance to second-generation ALKi resistances, may emerge in non-EML4-ALK variant 3 cases and is sensitive to third-generation lorlatinib. When in compound with one or more ALK KDMs, resistance to lorlatinib is expected. In the case of rampantly progressive disease, rebiopsy and redefining biology in a timely manner may be informative.

Anti-epidermal growth factor receptor therapy for glioblastoma in adults

BACKGROUND

Glioblastoma is an uncommon but highly aggressive type of brain tumour. Significant gains have been achieved in the molecular understanding and the pathogenesis of glioblastomas, however clinical improvements are difficult to obtain for many reasons. The current standard of care involves maximal safe surgical resection followed by chemoradiation and then adjuvant chemotherapy European Organisation for Research and Treatment of Cancer and the NCIC Clinical Trials Group (EORTC-NCIC) protocol with a median survival of 14.6 months. Successive phase III international randomised controlled studies have failed to significantly demonstrate survival advantage with newer drugs. Epidermal growth factor receptor (EGFR) is observed to be aberrant in 30% to 60% of glioblastomas. The receptor aberrancy is driven by abnormal gene amplification, receptor mutation, or both, in particular the extracellular vIII domain. EGFR abnormalities are common in solid tumours, and the advent of anti-EGFR therapies in non-small cell lung cancer and colorectal adenocarcinomas have greatly improved clinical outcomes. Anti-EGFR therapies have been investigated amongst glioblastomas, however questions remain about its ongoing role in glioblastoma management. This review aimed to report on the available evidence to date and perform a systematic analysis on the risks and benefits of use of anti-EGFR therapies in glioblastomas.

OBJECTIVES

To evaluate the efficacy and harms of anti-EGFR therapies for glioblastoma in adults.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, EBM Reviews databases, with supplementary handsearches to identify all available and relevant studies to 20 April 2020.

SELECTION CRITERIA

All randomised controlled trials (RCTs) using anti-EGFR therapies in adults with glioblastoma were eligible for inclusion. Anti-EGFR therapies included tyrosine kinase inhibitors, monoclonal antibodies, or vaccines. The comparison included investigational product added to standard of care versus standard of care or placebo, or investigational product against standard of care or placebo.

DATA COLLECTION AND ANALYSIS

The authorship team screened the search results and recorded the extracted data for analysis. We used standard Cochrane methodology to performed quantitative meta-analysis if two or more studies had appropriate and available data. Otherwise, we conducted a qualitative and descriptive analysis. We used the GRADE system to rate the certainty of the evidence. The analysis was performed along the two clinical settings: first-line (after surgery) and recurrent disease (after failure of first line treatment). Where information was available, we documented overall survival, progression-free survival, adverse events, and quality of life data from eligible studies.

MAIN RESULTS

The combined searches initially identified 912 records (after removal of duplicates), and further screening resulted in 19 records for full consideration. We identified nine eligible studies for inclusion in the review. There were three first-line studies and six recurrent studies. Five studies used tyrosine kinase inhibitors (TKIs); two studies used monoclonal antibodies; and two studies used targeted vaccines. More recent studies presented greater detail in the conduct of their studies and thus had a lower risk of bias. We observed no evidence benefit in overall survival with the use of anti-EGFR therapy in the first-line or recurrent setting (hazard ratio (HR) 0.89, 95% confidence interval (CI) 0.76 to 1.04; 3 RCTs, 1000 participants, moderate-certainty evidence; and HR 0.79, 95% CI 0.51 to 1.21, 4 RCTs, 489 participants, low-certainty evidence, respectively). All the interventions were generally well tolerated with low-certainty evidence for lymphopenia (odds ratio (OR) 0.97, 95% CI 0.19 to 4.81; 4 RCTs, 1146 participants), neutropenia (OR 1.29, 95% CI 0.82 to 2.03; 4 RCTs, 1146 participants), and thrombocytopenia (OR 3.69, 95% CI 0.51 to 26.51; 4 RCTs, 1146 participants). A notable toxicity relates to ABT-414, where significant ocular issues were detected. The addition of anti-EGFR therapy showed no evidence of an increase in progression-free survival (PFS) in the first-line setting (HR 0.94, 95% CI 0.81 to 1.10; 2 RCTs, 894 participants, low-certainty evidence). In the recurrent setting, there was an increase in PFS with the use of anti-EGFR therapy (HR 0.75, 95% CI 0.58 to 0.96, 3 RCTs, 275 participants, low-certainty evidence). The available quality of life assessment data showed that anti-EGFR therapies were neither detrimental or beneficial when compared to standard care (not estimable).

AUTHORS' CONCLUSIONS

In summary, there is no evidence of a demonstrable overall survival benefit with the addition of anti-EGFR therapy in first-line and recurrent glioblastomas. Newer drugs that are specially designed for glioblastoma targets may raise the possibility of success in this population, but data are lacking at present. Future studies should be more selective in pursuing people displaying specific EGFR targets.

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.

Temporal and spatial modulation of the tumor and systemic immune response in the murine Gl261 glioma model

Glioblastoma, the most aggressive form of glioma, has a 5-year survival rate of <5%. While radiation and immunotherapies are routinely studied in the murine Gl261 glioma model, little is known about its inherent immune response. This study quantifies the temporal and spatial localization of immune cell populations and mediators during glioma development. Eight-week old male C57Bl/6 mice were orthotopically inoculated with 1x106 Gl261 cells and tumor morphology, local and systemic immune cell populations, and plasma cytokines/chemokines assessed at day 0, 1, 3, 7, 14, and 21 post-inoculation by magnetic resonance imaging, chromogenic immunohistochemistry, multiplex immunofluorescent immunohistochemistry, flow cytometry and multiplex immunoassay respectively. From day 3 tumors were distinguishable with >30% Ki67 and increased tissue vascularization (p<0.05). Increasing tumor proliferation/malignancy and vascularization were associated with significant temporal changes in immune cell populations within the tumor (p<0.05) and systemic compartments (p = 0.02 to p<0.0001). Of note, at day 14 16/24 plasma cytokine/chemokines levels decreased coinciding with an increase in tumor cytotoxic T cells, natural killer and natural killer/T cells. Data derived provide baseline characterization of the local and systemic immune response during glioma development. They reveal that type II macrophages and myeloid-derived suppressor cells are more prevalent in tumors than regulatory T cells, highlighting these cell types for further therapeutic exploration.

Identification of Novel Biomarkers in Pancreatic Tumor Tissue to Predict Response to Neoadjuvant Chemotherapy

Background: Neoadjuvant chemotherapy (NAC) has been of recent interest as an alternative to upfront surgery followed by adjuvant chemotherapy in patients with pancreatic ductal adenocarcinoma (PDAC). However, a subset of patients does not respond to NAC and may have been better managed by upfront surgery. Hence, there is an unmet need for accurate biomarkers for predicting NAC response in PDAC. We aimed to identify upregulated proteins in tumor tissue from poor- and good-NAC responders.

Methods: Tumor and adjacent pancreas tissue samples were obtained following surgical resection from NAC-treated PDAC patients. SWATH-MS proteomic analysis was performed to identify and quantify proteins in tissue samples. Statistical analysis was performed to identify biomarkers for NAC response. Pathway analysis was performed to characterize affected canonical pathways in good- and poor-NAC responders.

Results: A total of 3,156 proteins were identified, with 19 being were significantly upregulated in poor-responders compared to good-responders (log₂ ratio > 2, p < 0.05). Those with the greatest ability to predict poor-NAC response were GRP78, CADM1, PGES2, and RUXF. Notably, canonical pathways that were significantly upregulated in good-responders included acute phase signaling and macrophage activation, indicating a heightened immune response in these patients.

Conclusion: A novel biomarker signature for poor-NAC response in PDAC was identified.

Tissue biomarker panel as a surrogate marker for squamous subtype of pancreatic cancer

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) has been recently classified into four subtypes based on the gene expression levels, with squamous subtype having worst prognostic outcomes. However, gene expression analysis for each individual patient is not clinically feasible due to very high associated cost. We previously reported that levels of three biomarkers (S100A4, Ca-125 and Mesothelin) can be used to classify PDAC patients based on their survival outcomes. This project aimed to determine if this novel biomarker panel can be used as a surrogate to identify squamous PDAC subtype.

METHODS

Using the Nanostring gene expression platform, tumor tissue from 24 PDAC patients were analysed for our novel biomarkers and markers associated with four PDAC subtypes.

RESULTS

Gene expression of our biomarker panel (S100A4, Ca-125 and Mesothelin) closely clustered together with markers for squamous PDAC subtype.

CONCLUSION

These results highlight the potential of our biomarkers to be utilized for identification of squamous PDAC subtype.

A multicenter study of thromboembolic events among patients diagnosed with ROS1-rearranged non-small cell lung cancer

OBJECTIVES

This study aimed to describe the longitudinal thromboembolism (TE) risk relative to the natural history of disease and clinical course of ROS1 rearranged non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

Cases of ROS1-rearranged NSCLC from six Australian hospitals were pooled and evaluated for incidence, timing, predictors and outcomes of venous or arterial TE, as well as objective response rate (ORR) to active therapy and overall survival (OS).

RESULTS

Of 42 patients recruited, 20 (48%) experienced TE; one (2%) arterial, 13 (31%) a pulmonary emboli (PE), and 12 (29%) a deep vein thrombosis. Among those with TE, six (30%) experienced multiple events, three as concurrent and three as recurrent diagnoses. The cumulative incidence of TE over time, adjusted for death as a competing risk factor, approached 50%. TE occurred prior to, during and post the peri-diagnostic period and occurred irrespective of treatment strategy. A thrombophilia was identified in n = 3/10 (30%) cases screened: in two factor V Leiden and in one anti-thrombin III (ATIII) deficiency. Median OS was 21.3 months in those with TE vs. 28.8 months in those without; hazard ratio 1.16 (95%CI 0.43-3.15). Respective ORR to first-line therapy with TE was 50% vs. 44% without TE in the chemotherapy arm and 67% vs. 50% in the targeted therapy arm.

CONCLUSION

In the rare cancer subtype, ROS1, these real-world data demonstrate sustained TE risk beyond the diagnostic period irrespective of therapeutic strategy. High incidence of PE, concurrent TE, and recurrent TE warrant validation in larger cohorts. Consideration of primary thromboprophylaxis in ROS1 populations is recommended.

Sub-acute Toxicity in Non-cancerous Tissue and Immune-Related Adverse Events of a Novel Combination Therapy for Cancer

Brain, lung, and colon tissue experience deleterious immune-related adverse events when immune-oncological agents or radiation are administered. However, there is a paucity of information regarding whether the addition of radiation to immuno-oncological regimens exacerbates the tissue inflammatory response. We used a murine model to evaluate sub-acute tissue damage and the systemic immune response in C57Bl/6 mice when administered systemic anti-programmed cell death protein 1 (αPD-1) immunotherapy alone or in combination with stereotactic fractionated 10 gray/5 X-ray radiation to normal brain, lung or colon tissue. The model indicated that combinatorial αPD-1 immunotherapy and radiation may alter normal colon cell proliferation and cerebral blood vasculature, and induce systemic thrombocytopenia, lymphopenia, immune suppression, and altered immune repertoire (including interleukin-1β). Therein our data supports close monitoring of hematological and immune-related adverse events in patients receiving combination therapy.

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.

Abstract 4531: SWATH-MS profiling identifies prognostic factors for progression-free survival (PFS) In INTEGRATE - A randomized phase II double-blind placebo-controlled study of regorafenib in refractory advanced oesophagogastric cancer (AOGC) - A study by the Australasian Gastrointestinal Trials Group (AGITG)

Introduction: Gastric cancer is one of the most common cancers worldwide, and a leading cause of cancer death. Advanced OesophagoGastric cancer (AOGC) has a poor prognosis despite treatment. The P2 INTEGRATE multinational 2:1 (active:placebo) randomized trial demonstrated the activity, on progression-free survival (PFS), of the oral multikinase inhibitor regorafenib (REG) in patients (pts) with refractory AOGC (Pavlakis et al JCO 2016), leading to the P3 INTEGRATE II trial (NCT02773524) currently underway. Here, we sought to identify prognostic protein biomarkers in a discovery analysis of a patient subset from INTEGRATE I.

Methods: The discovery analysis set comprised of 40 INTEGRATE I patients (12 placebo; 28 REG) selected using stratified random sampling based on quartiles of observed PFS within each arm of allocation, half from 1st quartile (worst PFS outcome) and half from 4th quartile (best PFS outcome). We profiled the plasma proteome of INTEGRATE pts using data-independent acquisition of liquid chromatography coupled with tandem mass spectrometry (SWATH-MS acquisition). Plasma collected at baseline (10µl) was analyzed with TripleTOF 6600 System (SCIEX, MA, USA). Data was searched against an “extended” spectral library generated using SwathXtendsoftware (Wu et al MCP 2016). Cox proportional hazard regression was used to assess the prognostic value of log2 protein expression level adjusted for treatment allocation.

Results: 437 proteins were identified across all 40 pt samples (&gt;99% peptide confidence). A subset of 27 proteins were identified as candidates for possible further investigation using the verification analysis set on the basis of having p-values &lt;0.05 (no p-value was significant after adjustment for multiple comparisons). These proteins were associated with (i) the immune system, including multiple immunoglobulin variable heavy and light chains, and proteins involved in complement activation (C09, C08G, C4BPA and C05 and others) and two serpins that regulate the acute phase response and promote cancer cell survival (AACT and A1AT); (ii) blood coagulation and angiogenesis (THBS1/PROS1/FBLN1 and others), also instrumental in tumor progression. Other proteins are known to promote local cancer cell adhesion, invasion and distant metastasis.

Conclusions: This is the first time that SWATH has been used to analyse AOGC pt samples, an otherwise challenging biofluid (undepleted plasma) for profiling. These proteins could represent a novel prognostic signature for PFS in AOGC patients, pending validation in the larger verification data set. This work highlights the potential value of incorporating proteomics into risk assessments guiding treatment strategies for patients.

Citation Format: Sarah A. Hayes, Andrew Martin, Sonia Yip, Viive M. Howell, Katrin M. Sjoquist, Eric Tsobanis, Yoon-Koo Kang, Yung-Jue Bang, Thierry Alcindor, Christopher J. O'Callaghan, Niall C. Tebbutt, John Simes, David Goldstein, Nick Pavlakis. SWATH-MS profiling identifies prognostic factors for progression-free survival (PFS) In INTEGRATE - A randomized phase II double-blind placebo-controlled study of regorafenib in refractory advanced oesophagogastric cancer (AOGC) - A study by the Australasian Gastrointestinal Trials Group (AGITG) [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 4531.

Biomarker panel predicts survival after resection in pancreatic ductal adenocarcinoma: A multi-institutional cohort study

BACKGROUND

Up to 60% of patients who undergo curative-intent pancreatic ductal adenocarcinoma (PDAC) resection experience disease recurrence within six months. We recently published a systematic review of prognostic immunohistochemical biomarkers in PDAC and shortlisted a panel of those reported with the highest level of evidence, including p53, p16, Ca-125, S100A4, FOXC1, EGFR, mesothelin, CD24 and UPAR. This study aims to discover and validate the prognostic significance of a combinatorial panel of tumor biomarkers in patients with resected PDAC.

METHODS

Patients who underwent PDAC resection were included from a single institution discovery cohort and a multi-institutional validation cohort. Tumors in the discovery cohort were stained immunohistochemically for all nine shortlisted biomarkers. Biomarkers significantly associated with overall survival (OS) were reevaluated as a combinatorial panel in both discovery and validation cohorts for its prognostic significance.

RESULTS

224 and 191 patients were included in the discovery and validation cohorts, respectively. In both cohorts, S100A4, Ca-125 and mesothelin expression were associated with shorter OS. In both cohorts, the number of these biomarkers expressed was significantly associated with OS (discovery cohort 36.8 vs. 26.4 vs 16.3 vs 12.8 months, P < 0.001; validation cohort 25.2 vs 18.3 vs 13.6 vs 11.9 months, P = 0.008 for expression of zero, one, two and three biomarkers, respectively). On multivariable analysis, expression of at least one of three biomarkers was independently associated with shorter OS.

CONCLUSION

Combinations of S100A4, Ca-125 and mesothelin expression stratify survival after resection of localized PDAC. Co-expression of all three biomarkers is associated with the poorest prognostic outcome.

Comparison of radiobiological parameters for 90Y radionuclide therapy (RNT) and external beam radiotherapy (EBRT) in vitro

Background

Dose rate variation is a critical factor affecting radionuclide therapy (RNT) efficacy. Relatively few studies to date have investigated the dose rate effect in RNT. Therefore, the aim of this study was to benchmark ⁹⁰Y RNT (at different dose rates) against external beam radiotherapy (EBRT) in vitro and compare cell kill responses between the two irradiation processes.

Results

Three human colorectal carcinoma (CRC) cell lines (HT29, HCT116, SW48) were exposed to ⁹⁰Y doses in the ranges 1–10.4 and 6.2–62.3 Gy with initial dose rates of 0.013–0.13 Gy/hr (low dose rate, LDR) and 0.077–0.77 Gy/hr (high dose rate, HDR), respectively. Results were compared to a 6-MV photon beam doses in the range from 1–9 Gy with constant dose rate of 277 Gy/hr. The cell survival parameters from the linear quadratic (LQ) model were determined. Additionally, Monte Carlo simulations were performed to calculate the average dose, dose rate and the number of hits in the cell nucleus.

For the HT29 cell line, which was the most radioresistant, the α/β ratio was found to be ≈ 31 for HDR–⁹⁰Y and ≈ 3.5 for EBRT. LDR–⁹⁰Y resulting in insignificant cell death compared to HDR–⁹⁰Y and EBRT. Simulation results also showed for LDR–⁹⁰Y, for doses ≲ 3 Gy, the average number of hits per cell nucleus is ≲ 2 indicating insufficiently delivered lethal dose. For ⁹⁰Y doses \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\gtrsim $\end{document}≳ 3 Gy the number of hits per nucleus decreases rapidly and falls below ≈ 2 after ≈ 5 days of incubation time. Therefore, our results demonstrate that LDR–⁹⁰Y is radiobiologically less effective than EBRT. However, HDR–⁹⁰Y at ≈ 56 Gy was found to be radiobiologically as effective as acute ≈ 8 Gy EBRT.

Conclusion

These results demonstrate that the efficacy of RNT is dependent on the initial dose rate at which radiation is delivered. Therefore, for a relatively long half-life radionuclide such as ⁹⁰Y, a higher initial activity is required to achieve an outcome as effective as EBRT.

BAMLET kills chemotherapy-resistant mesothelioma cells, holding oleic acid in an activated cytotoxic state

Malignant pleural mesothelioma is an aggressive cancer with poor prognosis. Here we have investigated in vitro efficacy of BAMLET and BLAGLET complexes (anti-cancer complexes consisting of oleic acid and bovine α-lactalbumin or β-lactoglobulin respectively) in killing mesothelioma cells, determined BAMLET and BLAGLET structures, and investigated possible biological mechanisms. We performed cell viability assays on 16 mesothelioma cell lines. BAMLET and BLAGLET having increasing oleic acid content inhibited human and rat mesothelioma cell line proliferation at decreasing doses. Most of the non-cancer primary human fibroblasts were more resistant to BAMLET than were human mesothelioma cells. BAMLET showed similar cytotoxicity to cisplatin-resistant, pemetrexed-resistant, vinorelbine-resistant, and parental rat mesothelioma cells, indicating the BAMLET anti-cancer mechanism may be different to drugs currently used to treat mesothelioma. Cisplatin, pemetrexed, gemcitabine, vinorelbine, and BAMLET, did not demonstrate a therapeutic window for mesothelioma compared with immortalised non-cancer mesothelial cells. We demonstrated by quantitative PCR that ATP synthase is downregulated in mesothelioma cells in response to regular dosing with BAMLET. We sought structural insight for BAMLET and BLAGLET activity by performing small angle X-ray scattering, circular dichroism, and scanning electron microscopy. Our results indicate the structural mechanism by which BAMLET and BLAGLET achieve increased cytotoxicity by holding increasing amounts of oleic acid in an active cytotoxic state encapsulated in increasingly unfolded protein. Our structural studies revealed similarity in the molecular structure of the protein components of these two complexes and in their encapsulation of the fatty acid, and differences in the microscopic structure and structural stability. BAMLET forms rounded aggregates and BLAGLET forms long fibre-like aggregates whose aggregation is more stable than that of BAMLET due to intermolecular disulphide bonds. The results reported here indicate that BAMLET and BLAGLET may be effective second-line treatment options for mesothelioma.

Glioblastoma Recurrence Correlates With Increased APE1 and Polarization Toward an Immuno-Suppressive Microenvironment

While treatment with surgery, radiotherapy and/or chemotherapy may prolong life for patients with glioblastoma, recurrence is inevitable. What is still being discovered is how much these treatments and recurrence of disease affect the molecular profiles of these tumors and how these tumors adapt to withstand these treatment pressures. Understanding such changes will uncover pathways used by the tumor to evade destruction and will elucidate new targets for treatment development. Nineteen matched pre-treatment and post-treatment glioblastoma tumors were subjected to gene expression profiling (Fluidigm, TaqMan assays), MGMT promoter methylation analysis (pyrosequencing) and protein expression analysis of the DNA repair pathways, known to be involved in temozolomide resistance (immunohistochemistry). Gene expression profiling to molecularly subtype tumors revealed that 26% of recurrent post-treatment specimens did not match their primary diagnostic specimen subtype. Post-treatment specimens had molecular changes which correlated with known resistance mechanisms including increased expression of APEX1 (p < 0.05) and altered MGMT methylation status. In addition, genes associated with immune suppression, invasion and aggression (GPNMB, CCL5, and KLRC1) and polarization toward an M2 phenotype (CD163 and MSR1) were up-regulated in post-treatment tumors, demonstrating an overall change in the tumor microenvironment favoring aggressive tumor growth and disease recurrence. This was confirmed by in vitro studies that determined that glioma cell migration was enhanced in the presence of M2 polarized macrophage conditioned media. Further, M2 macrophage-modulated migration was markedly enhanced in post-treatment (temozolomide resistant) glioma cells. These findings highlight the ability of glioblastomas to evade not only the toxic onslaught of therapy but also to evade the immune system suggesting that immune-altering therapies may be of value in treating this terrible disease.

Acinar cell density at the pancreatic resection margin is associated with post-pancreatectomy pancreatitis and the development of postoperative pancreatic fistula

BACKGROUND

There has been recent evidence supporting post-pancreatectomy pancreatitis as a factor in the development of postoperative pancreatic fistula (POPF). The aims of this study were to evaluate: (i) the correlation of the acinar cell density at the pancreatic resection margin with the intra-operative amylase concentration (IOAC) of peri-pancreatic fluid, postoperative pancreatitis, and POPF; and (ii) the association between postoperative pancreatitis on the first postoperative day and POPF.

METHODS

Consecutive patients who underwent pancreatic resection between June 2016 and July 2017 were included for analysis. Fluid for IOAC was collected, and amylase concentration was determined in drain fluid on postoperative days 1, 3, and 5. Serum amylase and lipase and urinary trypsinogen-2 concentrations were determined on the first postoperative day. Histology slides of the pancreatic resection margin were scored for acinar cell density.

RESULTS

Sixty-one patients were included in the analysis. Acinar cell density significantly correlated with IOAC (r = 0.566, p < 0.001), and was significantly associated with postoperative pancreatitis (p < 0.001), and POPF (p = 0.003). Postoperative pancreatitis was significantly associated with the development of POPF (OR 17.81, 95%CI 2.17-145.9, p = 0.001).

DISCUSSION

The development of POPF may involve a complex interaction between acinar cell density, immediate leakage of pancreatic fluid, and postoperative pancreatitis.

Pattern of care and survival of anaplastic lymphoma kinase rearranged non-small cell lung cancer (ALK+ NSCLC) in an Australian Metropolitan Tertiary Referral Centre: A retrospective cohort analysis

AIM

To report on the pattern of care and survival of anaplastic lymphoma kinase rearranged non-small cell lung cancer (ALK+NSCLC) in a real-world retrospective cohort from an Australian tertiary referral center.

METHODS

Individuals with a pathological diagnosis of ALK+NSCLC via immunohistochemistry and fluorescence in situ hybridization and a radiological diagnosis of stage IV disease were eligible. Patients were identified via the Pathology Department specimen database and electronic patient chart review. Data were collected and analyzed for baseline demographics, radiological pattern of disease and response to treatment, treatment sequencing, toxicity and survival.

RESULTS

Thirty-five patients were identified over a 7-year period from 2010 to 2016 and followed for a median of 23 months. Median overall survival (OS) in the entire cohort was immature at data cut, 46.0 months (95% confidence interval [CI], 22.53-69.47 months), with the longest surviving patient was alive 62.1 months since diagnosis. Objective radiological response rate overall across six potential treatments and six treatment lines (range 1-6) was 58.2%. Almost 50% received at-least two lines of ALK inhibitor therapy with median OS in this group estimated to be 53.4 months (95% CI, 35.1 months-not reached). Toxicity was manageable with a low rate of ≥ grade 3 toxicity (n = 7). Forty-eight percent relapsed within the CNS and 43% overall died due to CNS progression. In those with CNS diagnosis at baseline and/or progression within the CNS (n = 32), median OS was also 46.0 months (95% CI, 24.22-66.78 months).

CONCLUSION

This retrospective cohort analysis of a single tertiary institution experience in treating ALK+NSCLC demonstrates impressive OS and the importance and impact of careful management of CNS disease in this patient population.

Biodistribution and Clearance of Stable Superparamagnetic Maghemite Iron Oxide Nanoparticles in Mice Following Intraperitoneal Administration

Nanomedicine is an emerging field with great potential in disease theranostics. We generated sterically stabilized superparamagnetic iron oxide nanoparticles (s-SPIONs) with average core diameters of 10 and 25 nm and determined the in vivo biodistribution and clearance profiles. Healthy nude mice underwent an intraperitoneal injection of these s-SPIONs at a dose of 90 mg Fe/kg body weight. Tissue iron biodistribution was monitored by atomic absorption spectroscopy and Prussian blue staining. Histopathological examination was performed to assess tissue toxicity. The 10 nm s-SPIONs resulted in higher tissue-iron levels, whereas the 25 nm s-SPIONs peaked earlier and cleared faster. Increased iron levels were detected in all organs and body fluids tested except for the brain, with notable increases in the liver, spleen, and the omentum. The tissue-iron returned to control or near control levels within 7 days post-injection, except in the omentum, which had the largest and most variable accumulation of s-SPIONs. No obvious tissue changes were noted although an influx of macrophages was observed in several tissues suggesting their involvement in s-SPION sequestration and clearance. These results demonstrate that the s-SPIONs do not degrade or aggregate in vivo and intraperitoneal administration is well tolerated, with a broad and transient biodistribution. In an ovarian tumor model, s-SPIONs were shown to accumulate in the tumors, highlighting their potential use as a chemotherapy delivery agent.

Treatment of ALK-rearranged non-small cell lung cancer: A review of the landscape and approach to emerging patterns of treatment resistance in the Australian context

Since the identification of anaplastic lymphoma kinase (ALK) gene rearrangements in non-small cell lung cancer (NSCLC) in 2005, the treatment of ALK-rearranged NSCLC (ALK+ NSCLC) has evolved at a rapid pace. This molecularly distinct subset of NSCLC has uniquely important biology, clinicopathologic features and mechanisms of drug resistance which impact on the choice of treatment for a patient with this disease. There are multiple ALK tyrosine kinase inhibitors now available in clinical practice with efficacy data continuing to emerge and guide the optimal treatment algorithm. A detailed search of medical databases and clinical trial registries was conducted to capture all relevant articles on this topic enabling an updated detailed overview of the landscape of management of ALK-rearranged NSCLC.

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.

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.

Abstract 3886: Protein mapping of NSCLC cell lines: Defining mechanisms of acquired erlotinib resistance

Lung cancer is one of the most common and lethal malignancies globally, with non-small cell lung cancer (NSCLC) accounting for 85% of all lung cancer cases. Patients generally have a poor prognosis without treatment as most patients are diagnosed with advanced metastatic disease, when curative therapeutic options are limited. However, there has been a recent emphasis on identifying driver mutations responsible for patient tumours, which has paved the way for more effective targeted therapies in the treatment of NSCLC.

One such targeted therapy, erlotinib, is used as standard-of-care treatment in NSCLC patients with sensitising EGFR mutations. Although use of these tyrosine kinase inhibitors (TKIs) often leads to dramatic and prolonged response, acquired resistance eventually ensues. Understanding and overcoming the molecular basis of resistance to erlotinib remains a challenge for successful long-term treatment.

To identify mechanisms of erlotinib resistance, we used latest-generation mass spectrometry to comprehensively map the proteomes of two NSCLC cell lines: a parental NSCLC cell line sensitive to erlotinib (HCC827, contains a deletion in EGFR exon 19) and its matched erlotinib-resistant subline (HCC827_ER). Cell lines were treated with an IC50 dose of erlotinib or mock treatment. Three days after treatment, each cell line was profiled using the Sequential Windowed data independent Acquisition of the Total High-resolution Mass Spectra (SWATH-MS 2.0) algorithm, conducted on the Sciex 6600 TripleTOF. LC-MS/MS data was extracted for 3416 proteins (peptide confidence &gt;99%) following a Sciex ProteinPilot database search.

Overall, 33 proteins were differentially expressed between HCC827 mock and erlotinib treated cells, while expression levels of 59 proteins were significantly different between HCC827er mock and erlotinib treated cells (Fold Change&gt;2, p&lt;0.05). Ingenuity Pathway Analysis listed “Organismal Injury and Abnormalities” and “Cancer” as the leading Diseases and Disorders in both cell lines, with “Cellular Growth and Proliferation” and “Small Molecule Biochemistry” listed as the top Molecular and Cellular Functions in the sensitive and resistant cell line, respectively. In the parental cell line, identified proteins were associated with the regulation of the actin cytoskeleton, as well as the PI3K-Akt signaling pathway, which is commonly altered in human cancers. In the resistant subline, several differentially expressed proteins mapped to various metabolic pathways (including carbon, glycine, serine and threonine metabolism), with some proteins similarly involved in PI3K-Akt signaling.

This is the first time that lung cancer cell lines have been comprehensively profiled by SWATH-MS. Protein mapping will help to increase the understanding of the mechanisms involved in the acquisition of TKI resistance, which is crucial for the development of rational strategies to overcome resistance in the clinic.

Citation Format: Sarah A. Hayes, Christoph Krisp, Amanda L. Hudson, Rozelle Harvie, Csilla Hasovits, Stephen Clarke, Mark P. Molloy, Viive M. Howell. Protein mapping of NSCLC cell lines: Defining mechanisms of acquired erlotinib resistance. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3886.

Abstract 764: LOX and LOXL2 inhibition as a treatment for ovarian cancer

Epithelial ovarian cancer (EOC) is the most lethal gynecological malignancy in women. Despite advances in our understanding of the molecular biology of EOC, patient survival has not significantly improved in decades and new treatments are needed. There is increased interest in therapeutic targeting of the tumor microenvironment (TME). The lysyl oxidase (LOX) family of enzymes are involved in extracellular matrix remodelling through crosslinking of collagen and elastin. They have been shown to play an important role in the TME of other cancers and are regulated by hypoxia, however little is known about their role in EOC. Therefore we aimed to investigate the role of LOX and LOXL2 in EOC using in vitro models.

Tumor epithelial (n = 2) and matched cancer-associated fibroblast cell lines (n = 2) derived from an SV40-induced mouse model of EOC were generated. MTT assays were performed on all cell lines to assess the effect of LOX and LOXL2 inhibition on cell viability. The effect of LOX and LOXL2 inhibition on cancer cell migration and invasion towards cancer-associated fibroblast conditioned media was also investigated using transwell assays. RNA and protein were isolated and analysed from cells cultured in normoxic and hypoxic conditions to assess whether LOX and LOXL2 gene and protein expression is regulated by hypoxia.

Inhibition of LOX and LOXL2 did not affect cell viability. LOX and LOXL2 inhibition significantly reduced the migration and invasion of EOC cells towards cancer-associated fibroblast conditioned media in vitro (p&lt;0.05). Gene expression analysis comparing Lox and Loxl2 expression in all cell lines demonstrated a significant increase in Lox and Loxl2 expression in cells cultured in hypoxia (p&lt;0.05). Similarly, cellular and secreted LOX and LOXL2 protein expression was increased in cells cultured in hypoxic conditions, supporting hypoxia as a regulator of LOX and LOXL2 expression.

This study demonstrates a role for LOX and LOXL2 in promoting migration and invasion of EOC cells in vitro. The upregulation of LOX and LOXL2 in hypoxia suggests a role in facilitating tumor growth and progression within hypoxic tumors. These results provide support for the utility of LOX and LOXL2 inhibition as promising and novel therapeutic strategies in EOC.

Citation Format: Angela Cho, Amanda L. Hudson, Samuel Yuen, Nham Tran, Viive M. Howell, Emily K. Colvin. LOX and LOXL2 inhibition as a treatment for ovarian cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 764.

Exhaled breath condensate for lung cancer protein analysis: a review of methods and biomarkers

Lung cancer is a leading cause of cancer-related deaths worldwide, and is considered one of the most aggressive human cancers, with a 5 year overall survival of 10-15%. Early diagnosis of lung cancer is ideal; however, it is still uncertain as to what technique will prove successful in the systematic screening of high-risk populations, with the strongest evidence currently supporting low dose computed tomography (LDCT). Analysis of exhaled breath condensate (EBC) has recently been proposed as an alternative low risk and non-invasive screening method to investigate early-stage neoplastic processes in the airways. However, there still remains a relative paucity of lung cancer research involving EBC, particularly in the measurement of lung proteins that are centrally linked to pathogenesis. Considering the ease and safety associated with EBC collection, and advances in the area of mass spectrometry based profiling, this technology has potential for use in screening for the early diagnosis of lung cancer. This review will examine proteomics as a method of detecting markers of neoplasia in patient EBC with a particular emphasis on LC, as well as discussing methodological challenges involving in proteomic analysis of EBC specimens.

Intratumoral heterogeneity identified at the epigenetic, genetic and transcriptional level in glioblastoma

Heterogeneity is a hallmark of glioblastoma with intratumoral heterogeneity contributing to variability in responses and resistance to standard treatments. Promoter methylation status of the DNA repair enzyme O⁶-methylguanine DNA methyltransferase (MGMT) is the most important clinical biomarker in glioblastoma, predicting for therapeutic response. However, it does not always correlate with response. This may be due to intratumoral heterogeneity, with a single biopsy unlikely to represent the entire lesion. Aberrations in other DNA repair mechanisms may also contribute. This study investigated intratumoral heterogeneity in multiple glioblastoma tumors with a particular focus on the DNA repair pathways. Transcriptional intratumoral heterogeneity was identified in 40% of cases with variability in MGMT methylation status found in 14% of cases. As well as identifying intratumoral heterogeneity at the transcriptional and epigenetic levels, targeted next generation sequencing identified between 1 and 37 unique sequence variants per specimen. In-silico tools were then able to identify deleterious variants in both the base excision repair and the mismatch repair pathways that may contribute to therapeutic response. As these pathways have roles in temozolomide response, these findings may confound patient management and highlight the importance of assessing multiple tumor biopsies.

Abstract B39: Intratumoral heterogeneity of DNA repair pathways in glioblastoma

Heterogeneity is a hallmark of glioblastoma with intratumoral heterogeneity contributing to variability in responses and resistance to standard treatments. DNA repair mechanisms are key elements involved in the response to temozolomide with epigenetic silencing of the O6-methylguanine methyltransferase (MGMT) promoter being a predictive biomarker for temozolomide response. However, response to temozolomide is highly variable and not always predicted by MGMT promoter methylation status. The mismatch repair (MMR) and base excision repair (BER) pathways have also been shown to be involved in treatment response with aberrations in these pathways leading to chemo-resistance and poor response to therapy. Thus changes in these pathways may confer resistance to temozolomide which is independent of MGMT methylation. Further, intratumoral heterogeneity in these pathways may also exacerbate resistance leading to worse outcomes. This study investigated intratumoral heterogeneity in glioblastoma with a particular focus on the DNA repair pathways.

The cohort comprised 14 cases of glioblastoma with 2 - 6 tumor tissue biopsies (5-10mm3) per case resected from regions at least 1cm apart. Classification of transcriptional subtype was performed by gene expression profiling (Fluidigm, Taqman assays). Pyrosequencing was used to identify MGMT promoter methylation. Expression of MMR and BER genes was determined using qRT-PCR and Taqman assays and deep sequencing of these genes was performed using the MiSeq Illumina platform and Avadis NGS software.

Gene expression profiling using two different limited gene-sets classified tumor specimens into the 3 major transcriptional subtypes, proneural, classical and mesenchymal, with strong concordance. These clustering techniques were then applied to tumor biopsies from the same individual. Transcriptional intratumoral heterogeneity defined as biopsies from the same individual being classified into different subtypes was identified in 40% of the patients. Intratumoral heterogeneity was also identified in the DNA repair pathways. Variability in MGMT methylation status was found in 14% of cases. In each case the percentage methylation varied up to 4-fold and the methylation status was independent of transcriptional classification. Intratumoral variation in the expression of the MMR genes MSH2 and PMS2 was identified in 15% and 20% of cases respectively and in 50% and 30% of cases for the BER genes PARP1 and APEX1. Significant heterogeneity within specimens was not identified for MMR genes MSH6 or MLH1. Targeted next generation sequencing of these 6 genes confirmed the presence of intratumoral heterogeneity at the mutation level. Up to 80 sequence variants were identified in each specimen, with 35 – 56 variants common across all specimens from a case, up to 20 shared between at least 2 specimens in a case and between 1 and 37 unique to each specimen within a case.

This study identified intratumoral heterogeneity of DNA repair pathways in glioblastomas, at the genomic, transcriptional and mutational levels. These pathways have roles in the responsiveness of glioblastomas to temozolomide. As such, intratumoral heterogeneity may confound patient management. Therefore, these results highlight the importance of assessing results from multiple tumor biopsies in order to correctly manage glioblastoma patients and their treatment.

Citation Format: Nicole R. Parker, Amanda L. Hudson, Peter Khong, Jonathon F. Parkinson, Rowan Ikin, Zhangkai Jason Cheng, Fatemeh Vafaee, Helen R. Wheeler, Viive M. Howell. Intratumoral heterogeneity of DNA repair pathways in glioblastoma. [abstract]. In: Proceedings of the AACR Special Conference: Advances in Brain Cancer Research; May 27-30, 2015; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2015;75(23 Suppl):Abstract nr B39.

The Extracellular Matrix in Epithelial Ovarian Cancer - A Piece of a Puzzle

Epithelial ovarian cancer is the fifth leading cause of cancer-related deaths in women and the most lethal gynecological malignancy. Extracellular matrix (ECM) is an integral component of both the normal and tumor microenvironment. ECM composition varies between tissues and is crucial for maintaining normal function and homeostasis. Dysregulation and aberrant deposition or loss of ECM components is implicated in ovarian cancer progression. The mechanisms by which tumor cells induce ECM remodeling to promote a malignant phenotype are yet to be elucidated. A thorough understanding of the role of the ECM in ovarian cancer is needed for the development of effective biomarkers and new therapies.

Orthotopic Implantation and Peripheral Immune Cell Monitoring in the II-45 Syngeneic Rat Mesothelioma Model

The enormous upsurge of interest in immune-based treatments for cancer such as vaccines and immune checkpoint inhibitors, and increased understanding of the role of the tumor microenvironment in treatment response, collectively point to the need for immune-competent orthotopic models for pre-clinical testing of these new therapies. This paper demonstrates how to establish an orthotopic immune-competent rat model of pleural malignant mesothelioma. Monitoring disease progression in orthotopic models is confounded by the internal location of the tumors. To longitudinally monitor disease progression and its effect on circulating immune cells in this and other rat models of cancer, a single tube flow cytometry assay requiring only 25 µl whole blood is described. This provides accurate quantification of seven immune parameters: total lymphocytes, monocytes and neutrophils, as well as the T-cell subsets CD4 and CD8, B-cells and Natural Killer cells. Different subsets of these parameters are useful in different circumstances and models, with the neutrophil to lymphocyte ratio having the greatest utility for monitoring disease progression in the mesothelioma model. Analyzing circulating immune cell levels using this single tube method may also assist in monitoring the response to immune-based treatments and understanding the underlying mechanisms leading to success or failure of treatment.

Reporting in studies of protein biomarkers of prognosis in colorectal cancer in relation to the REMARK guidelines

PURPOSE

The REMARK guidelines give authors comprehensive and specific advice on the complete and transparent reporting of studies of prognostic tumor markers. The aim of this study was to use the REMARK guidelines to evaluate the quality of reporting in a sample of studies assessing tissue-based protein markers for survival after resection of colorectal cancer.

EXPERIMENTAL DESIGN

Eighty pertinent articles were scored according to their conformity to 26 items derived from the REMARK criteria.

RESULTS

Overall, on a scale of adequacy of reporting that potentially ranged from 26 to 78, the median for these studies was 60 (interquartile range 54-64) and several criteria were adequately covered in a large proportion of studies. However, others were either not dealt with or inadequately covered, including description of the study design (35%), definition of survival endpoints (48%), adjuvant therapy (54%), follow-up procedures and time (59%), neoadjuvant therapy (63%), inclusion/exclusion criteria (73%), multivariable modeling methods and results (74%), and discussion of study limitations (85%).

CONCLUSIONS AND CLINICAL RELEVANCE

Inadequacies in presentation militate against comparability among protein marker studies and undermine the generalizability of their findings. The quality of reporting could be improved if journal editors were to require authors to ensure that their work satisfied the REMARK criteria.

Genomic alterations as mediators of miRNA dysregulation in ovarian cancer

Ovarian cancer is the fifth most common cause of cancer death in women worldwide. Serous epithelial ovarian cancer (SEOC) is the most common and aggressive histological subtype. Widespread genomic alterations go hand-in-hand with aberrant DNA damage signaling and are a hallmark of high-grade SEOC. MicroRNAs (miRNAs) are a class of small noncoding RNA molecules that are nonrandomly distributed in the genome. They are frequently located in chromosomal regions susceptible to copy number variation (CNV) associated with malignancy that can influence their expression. Widespread changes in miRNA expression have been reported in multiple cancer types including ovarian cancer. This review examines CNV and single nucleotide polymorphisms, two common types of genomic alterations that occur in ovarian cancer, in the context of their influence on the expression of miRNA and the ability of miRNA to bind to and regulate their target genes. This includes genes encoding proteins involved in DNA repair and the maintenance of genomic stability. Improved understanding of mechanisms of miRNA dysregulation and the role of miRNA in ovarian cancer will provide further insight into the pathogenesis and treatment of this disease.

Establishing a panel of chemo-resistant mesothelioma models for investigating chemo-resistance and identifying new treatments for mesothelioma

Mesothelioma is inherently chemo-resistant with only 50% of patients responding to the standard of care treatments, and consequently it has a very grim prognosis. The aim of this study was to establish a panel of chemo-resistant mesothelioma models with clinically relevant levels of resistance as tools for investigating chemo-resistance and identifying new treatments for mesothelioma. Chemo-resistant cell lines were established in vitro and characterized in vivo using syngeneic Fischer rats. Tumors derived from all chemo-resistant cell lines were immunohistochemically classified as mesothelioma. Homozygous deletion of p16^INK4A/p14^ARF and increased expression of several ATP-binding cassette transporters were demonstrated, consistent with findings in human mesothelioma. Further, the acquisition of chemo-resistance in vitro resulted in changes to tumor morphology and overall survival. In conclusion, these models display many features corresponding with the human disease, and provide the first series of matched parental and chemo-resistant models for in vitro and in vivo mesothelioma studies.

From mice to men: GEMMs as trial patients for new NSCLC therapies

Given the large socio-economic burden of cancer, there is an urgent need for in vivo animal cancer models that can provide a rationale for personalised therapeutic regimens that are translatable to the clinic. Recent developments in establishing mouse models that closely resemble human lung cancers involve the application of genetically engineered mouse models (GEMMs) for use in drug efficacy studies or to guide patient therapy. Here, we review recent applications of GEMMs in non-small cell lung cancer research for drug development and their potential in aiding biomarker discovery and understanding of biological mechanisms behind clinical outcomes and drug interactions.

Genetically engineered insertional mutagenesis in mice to model cancer: Sleeping Beauty

The ability to accurately model human cancer in mice enables in vivo examination of the biological mechanisms related to cancer initiation and progression as well as preclinical testing of new anticancer treatments and potential targets. The emergence of the genetically engineered Sleeping Beauty system of insertional mutagenesis has led to the development of a new generation of genetic mouse models of cancer and identification of novel cancer-causing genes. This chapter reviews the published cancer models of Sleeping Beauty and strategies using available strains to generate several models of cancer.

Abstract A10: A mutagenesis screen identifies tumor suppressors and kinases as potential driver genes of ovarian cancer

Background: The goal of this project is to increase our understanding of the molecular aetiology of ovarian cancer by utilizing Sleeping Beauty (SB) insertional mutagenesis.

Methods: Breeding colonies of the following genetically engineered mice were established and cross bred: homozygous floxed SB (STOCK Rosa26-LsL-D-SB11;T2/Onc2,TG6113), homozygous floxed Brca1 knock-out (C57BL/6.Brca1tm2Brn) and Tp53 mutant (C57BL/6-Trp53tm1Tyj/J). CRE recombinase packaged into an adenoviral vector (AdCreM2, MicroBix Biosystems Inc, CA) was surgically injected under the ovarian bursal membrane of mature female mice to delete Brca1 and activate SB mutagenesis in the ovarian surface epithelium. Mice were monitored and sacrificed at ethically defined endpoints or a maximum of 15 months post-surgery. Tumors were assessed for SB transposase activity by immunohistochemical staining. DNA was extracted from paraffin embedded sections of ovarian tumors and underwent high-throughput sequencing for T2/Onc2 insertion sites (Illumina, University of Iowa). Genes with insertion sites were interrogated against SEOC data from The Cancer Genome Atlas (TCGA) to identify genes also altered in the human malignancy. Functional annotation clustering was performed using DAVID (Database for Annotation, Visualization and Integrated Discovery, v6.7).

Results: Ovarian tumors were observed at low penetrance starting at 30 weeks post-surgery in SBflox/+Tp53mut/+ mice (6%, 3/48) and SBflox/+Brca1flox/flox p53mut/+ mice (8%, 4/50). No ovarian tumors were observed in SBflox/+Brca1flox/flox mice (n=38) or in SBflox/+Brca1flox/+ mice (n=26). Sequencing of the insertion sites identified a number of genes of which 67 were altered in 10 - 30% of cases in the TCGA SEOC dataset (N = 316). This gene-set was enriched for kinases (P = 0.003, False discovery rate (FDR) = 3%) including Fgfr2, Dyrk1a and Gsk3b, and small GTPase regulators (P = 0.01, FDR = 11%) including Smap2, Trio and Dock10. Other genes of interest included tumor suppressor genes Arid1b, Cdh4 and Wwox and the E3 ubiquitin ligase Ube3a. In the TCGA dataset, decreased progression free survival was associated with high expression of GSK3B, TRIO and UBE3A and low expression of WWOX.

Conclusions: This screen identified a number of novel potential driver genes of ovarian cancer. In addition genes previously associated with ovarian cancer were also identified, providing proof of principle for this approach. Investigation of these novel genes may lead to further insights into the pathogenesis of ovarian cancer.

This work was supported by Cancer Institute NSW, Cancer Council NSW and The Northern Translational Cancer Research Unit, NSW, Australia.

Citation Format: Emily K. Colvin, Emily Fuller, Jizhou Cheng, Anthony Gill, Deborah J. Marsh, Viive M. Howell. A mutagenesis screen identifies tumor suppressors and kinases as potential driver genes of 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 A10.

Predicting chemotherapeutic response and toxicity in colorectal cancer

SUMMARY While treatment for colorectal cancer has evolved significantly over the past 10 years with the introduction of active chemotherapeutic agents and targeted therapies, this has been at the cost of increased toxicity for patients; and significant financial burden for governments and patients. Predicting clinical outcomes, especially given the largely elderly patient population involved, is therefore paramount. This review seeks to summarize existing data regarding the prediction of response and toxicity to chemotherapy agents currently used in the treatment of colorectal cancer.

Abstract 330: Utilization of Sleeping Beauty mutagenesis for the identification of potential driver genes of ovarian cancer

Background: The goal of this project is to increase our understanding of the molecular aetiology of ovarian cancer by developing a mouse model of this tumor. Inherited mutation of BRCA1 is the best known risk factor for the most common subtype of ovarian cancer, i.e. serous epithelial ovarian cancer (SEOC); however, loss of Brca1 alone is insufficient for SEOC development in the mouse. Somatic mutation of TP53 is the most common molecular change in SEOC, but does not result in SEOC in the mouse, either alone or in combination with loss of Brca1. These findings suggest that additional currently unknown genetic factors are required for ovarian carcinogenesis. We hypothesized that random mutagenesis would activate these genetic factors and utilized Sleeping Beauty (SB) insertional mutagenesis to initiate ovarian tumors in mice that we have sequenced to determine potential genetic drivers of these tumors.

Methods: Breeding colonies of the following genetically engineered mice were established and cross bred: homozygous floxed SB (STOCK Rosa26-LsL-D-SB11;T2/Onc2,TG6113), homozygous floxed Brca1 knock-out (C57BL/6.Brca1tm2Brn) and Tp53 mutant (C57BL/6-Trp53tm1Tyj/J). CRE recombinase packaged into an adenoviral vector (AdCreM2, MicroBix Biosystems Inc, CA) was surgically injected under the ovarian bursal membrane of mature female mice to delete Brca1 and activate SB mutagenesis in the ovarian surface epithelium. Mice were monitored and sacrificed at ethically defined endpoints or a maximum of 15 months post-surgery. Tumors were assessed for SB transposase activity by immunohistochemical staining. DNA was extracted from paraffin embedded sections of ovarian tumors and underwent high-throughput sequencing for T2/Onc2 insertion sites (Illumina, University of Iowa).

Results: Ovarian tumors were observed at low penetrance starting at 30 weeks post-surgery in SBflox/+Tp53mut/+ mice (6%, 3/48) and SBflox/+Brca1flox/flox p53mut/+ mice (8%, 4/50). No ovarian tumors were observed in SBflox/+Brca1flox/flox mice (n=38) or in SBflox/+Brca1flox/+ mice (n=26). Sequencing of the insertion sites identified a number of genes of interest including kinases and tumor suppressors.

Conclusions: While ovarian cancer had low penetrance in these models, a number of potential driver genes were identified which may provide insights into the pathogenesis of these tumors. The low penetrance of tumor from targeted epithelial cells with SB T2/Onc2 is similar to that seen for pancreatic cancer. For this reason, mice with SB T2/Onc3 which is reported to preferentially induce epithelial tumors are currently being monitored for the development of ovarian tumors.

This work was supported by Cancer Institute NSW, Cancer Council NSW and The Northern Translational Cancer Research Unit, NSW, Australia.

Citation Format: Emily K. Colvin, Emily Fuller, Jizhou Cheng, Anthony Gill, Deborah J. Marsh, Viive M. Howell. Utilization of Sleeping Beauty mutagenesis for the identification of potential driver genes of ovarian cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 330. doi:10.1158/1538-7445.AM2013-330

Molecular diagnosis of primary hyperparathyroidism in familial cancer syndromes

In the last few years, causative genes have been identified for most of the familial hyperparathyroidism conditions. Germline mutations in the tumour suppressors multiple endocrine neoplasia type 1 (MEN1) and hyperparathyroidism 2 (HRPT2) provide a molecular diagnosis of multiple endocrine neoplasia type 1 and hyperparathyroidism jaw tumour syndrome, respectively. Germline mutations in the proto-oncogene RET (rearranged during transfection) provide a molecular diagnosis of multiple endocrine neoplasia type 2. Germline mutations of both MEN1 and, less frequently HRPT2, have been found in familial isolated hyperparathyroidism. A molecular diagnosis can now be incorporated into the management of patients with these conditions, however, the ease of diagnostics and value of genetic information in the context of clinical screening and early surgical intervention varies between these disorders. This review focuses on familial hyperparathyroidism and its known causative genes in the setting of neoplastic syndromes, with particular discussion of recent developments in the molecular diagnosis of parathyroid carcinoma.

Elevated levels of circulating microRNA-200 family members correlate with serous epithelial ovarian cancer

Background

There is a critical need for improved diagnostic markers for high grade serous epithelial ovarian cancer (SEOC). MicroRNAs are stable in the circulation and may have utility as biomarkers of malignancy. We investigated whether levels of serum microRNA could discriminate women with high-grade SEOC from age matched healthy volunteers.

Methods

To identify microRNA of interest, microRNA expression profiling was performed on 4 SEOC cell lines and normal human ovarian surface epithelial cells. Total RNA was extracted from 500 μL aliquots of serum collected from patients with SEOC (n = 28) and age-matched healthy donors (n = 28). Serum microRNA levels were assessed by quantitative RT-PCR following preamplification.

Results

microRNA (miR)-182, miR-200a, miR-200b and miR-200c were highly overexpressed in the SEOC cell lines relative to normal human ovarian surface epithelial cells and were assessed in RNA extracted from serum as candidate biomarkers. miR-103, miR-92a and miR -638 had relatively invariant expression across all ovarian cell lines, and with small-nucleolar C/D box 48 (RNU48) were assessed in RNA extracted from serum as candidate endogenous normalizers. No correlation between serum levels and age were observed (age range 30-79 years) for any of these microRNA or RNU48. Individually, miR-200a, miR-200b and miR-200c normalized to serum volume and miR-103 were significantly higher in serum of the SEOC cohort (P < 0.05; 0.05; 0.0005 respectively) and in combination, miR-200b + miR-200c normalized to serum volume and miR-103 was the best predictive classifier of SEOC (ROC-AUC = 0.784). This predictive model (miR-200b + miR-200c) was further confirmed by leave one out cross validation (AUC = 0.784).

Conclusions

We identified serum microRNAs able to discriminate patients with high grade SEOC from age-matched healthy controls. The addition of these microRNAs to current testing regimes may improve diagnosis for women with SEOC.

Low-Dose Spironolactone Prevents Apoptosis Repressor With Caspase Recruitment Domain Degradation During Myocardial Infarction

Low-dose mineralocorticoid receptor antagonists reduce morbidity and mortality in patients with heart failure and myocardial infarction, despite normal plasma aldosterone levels. Since apoptosis plays an important role in heart failure and postinfarction left ventricular remodeling, we examined whether low-dose mineralocorticoid receptor antagonists modulate cardiomyocyte death by regulating the apoptosis repressor protein apoptosis repressor with caspase recruitment domain to lessen the extent of apoptosis. Hearts from adult male Sprague-Dawley rats were subjected to regional ischemia followed by reperfusion ex vivo, with mineralocorticoid receptor antagonists added to perfusates before ischemia. Low-dose spironolactone (10 nmol/L) or eplerenone (100 nmol/L) significantly reduced infarct size. Spironolactone also prevented cleavage of the apoptotic chromatin condensation inducer in the nucleus and of the inhibitor of caspase-activated DNAse induced by ischemia-reperfusion, thereby abolishing chromatin condensation and internucleosomal cleavage. Ischemia-reperfusion–induced activation of caspases 2, 3, and 9, but not caspase 8, was prevented by spironolactone, suggesting targeted regulation of the intrinsic pathway. Low-dose spironolactone and eplerenone prevented loss of the apoptosis repressor with the caspase recruitment domain and reduced myocyte death. In H9c2 cells, mineralocorticoid receptor activation by aldosterone resulted in apoptosis repressor with caspase recruitment domain degradation and enhanced apoptosis; these actions were prevented by coadministration of spironolactone. Using a triple lysine mutant we identified that aldosterone enhances posttranscriptional degradation of the apoptosis repressor with a caspase recruitment domain via the ubiquitin-proteasomal pathway. Our data demonstrate that low-dose mineralocorticoid receptor antagonists reduce infarct size and apoptosis in the reperfused myocardium by preventing the apoptosis repressor with caspase recruitment domain degradation.