An Effective Epigenetic-PARP Inhibitor Combination Therapy for Breast and Ovarian Cancers Independent of BRCA Mutations

Purpose: PARP inhibitors (PARPi) are primarily effective against BRCA1/2-mutated breast and ovarian cancers, but resistance due to reversion of mutated BRCA1/2 and other mechanisms is common. Based on previous reports demonstrating a functional role for DNMT1 in DNA repair and our previous studies demonstrating an ability of DNA methyltransferase inhibitor (DNMTi) to resensitize tumors to primary therapies, we hypothesized that combining a DNMTi with PARPi would sensitize PARPi-resistant breast and ovarian cancers to PARPi therapy, independent of BRCA status.Experimental Design: Breast and ovarian cancer cell lines (BRCA-wild-type/mutant) were treated with PARPi talazoparib and DNMTi guadecitabine. Effects on cell survival, ROS accumulation, and cAMP levels were examined. In vivo, mice bearing either BRCA-proficient breast or ovarian cancer cells were treated with talazoparib and guadecitabine, alone or in combination. Tumor progression, gene expression, and overall survival were analyzed.Results: Combination of guadecitabine and talazoparib synergized to enhance PARPi efficacy, irrespective of BRCA mutation status. Coadministration of guadecitabine with talazoparib increased accumulation of ROS, promoted PARP activation, and further sensitized, in a cAMP/PKA-dependent manner, breast and ovarian cancer cells to PARPi. In addition, DNMTi enhanced PARP "trapping" by talazoparib. Guadecitabine plus talazoparib decreased xenograft tumor growth and increased overall survival in BRCA-proficient high-grade serous ovarian and triple-negative breast cancer models.Conclusions: The novel combination of the next-generation DNMTi guadecitabine and the first-in-class PARPi talazoparib inhibited breast and ovarian cancers harboring either wild-type- or mutant-BRCA, supporting further clinical exploration of this drug combination in PARPi-resistant cancers. Clin Cancer Res; 24(13); 3163-75. ©2018 AACR.

Protein kinase A-mediated phosphorylation regulates STAT3 activation and oncogenic EZH2 activity

Polycomb Repressive Complex 2 (PRC2) member enhancer of zeste homologue 2 (EZH2) trimethylates histone H3 lysine 27 (H3K27me3), alters chromatin structure and contributes to epigenetic regulation of gene expression in normal and disease processes. Phosphorylation of EZH2 augmented EZH2 oncogenic activity in cancer but observations have been limited to serine 21 (S21) residue by protein kinase B. In addition, phosphorylation of the evolutionarily conserved T372 motif of EZH2 by p38 resulted in EZH2 interaction with Ying Yang 1 and promoted muscle stem cell differentiation. In the present study, we used epithelial ovarian cancer (OC) cells as a model to demonstrate that phosphorylation of EZH2 at T372 by protein kinase A (PKA) induced a dominant-negative EZH2 phenotype, inhibited OC cell proliferation and migration in vitro and decreased ovarian xenograft tumor growth in vivo. Phosphorylation of T372 by PKA enhanced the interaction between EZH2 and signal transducer and activator of transcription 3 (STAT3), and STAT3 binding to pT372-EZH2 reduced cellular levels of pSTAT3 and downregulated interleukin 6 receptor expression in OC. Furthermore, PKA-mediated pT372-EZH2 decreased ATP levels and altered mitochondrial gene expression, resulting in mitochondrial dysfunction and reduced OC cell growth. These findings demonstrate that PKA-mediated T372 phosphorylation reduces oncogenic EZH2 activity and reveal a novel role for pT372 in regulating EZH2 in OC and possibly other cancers.

A Phase I Clinical Trial of Guadecitabine and Carboplatin in Platinum-Resistant, Recurrent Ovarian Cancer: Clinical, Pharmacokinetic, and Pharmacodynamic Analyses

Purpose: Epigenetic changes are implicated in acquired resistance to platinum. Guadecitabine is a next-generation hypomethylating agent (HMA). Here, we report the clinical results, along with pharmacokinetic (PK) and pharmacodynamic analyses of the phase I study of guadecitabine and carboplatin in patients with recurrent, platinum-resistant high-grade serous ovarian cancer, primary peritoneal carcinoma (PPC), or fallopian tube cancer (FTC).Experimental Design: Guadecitabine was administered once daily on days 1 to 5 followed by carboplatin i.v. on day 8 of a 28-day cycle. Patients had either measurable or detectable disease. Safety assessments used CTCAE v4.Results: Twenty patients were enrolled and treated. Median age was 56 years (38-72 years). The median number of prior regimens was 7 (1-14). In the first cohort (N = 6), the starting doses were guadecitabine 45 mg/m² and carboplatin AUC5. Four patients experienced dose-limiting toxicity (DLT; neutropenia and thrombocytopenia), leading to dose deescalation of guadecitabine to 30 mg/m² and of carboplatin to AUC4. No DLTs were observed in the subsequent 14 patients. Grade ≥3 adverse events ≥10% were neutropenia, leukopenia, anemia, nausea, vomiting, ascites, constipation, hypokalemia, pulmonary embolism, small-intestinal obstruction, and thrombocytopenia. Three patients had a partial response (PR), and 6 patients had stable disease (SD) >3 months, for an overall response rate (ORR) and clinical benefit rate of 15% and 45%, respectively. LINE-1 demethylation in PBMCs and promoter demethylation/gene reexpression in paired tumor biopsies/ascites were recorded.Conclusions: Guadecitabine and carboplatin were tolerated and induced clinical responses in a heavily pretreated platinum-resistant ovarian cancer population, supporting a subsequent randomized phase II trial. Clin Cancer Res; 24(10); 2285-93. ©2018 AACR.

Genomic and Epigenomic Signatures in Ovarian Cancer Associated with Resensitization to Platinum Drugs

DNA methylation aberrations have been implicated in acquired resistance to platinum drugs in ovarian cancer. In this study, we elucidated an epigenetic signature associated with platinum drug resensitization that may offer utility in predicting the outcomes of patients who are coadministered a DNA methyltransferase inhibitor. The ovarian cancer specimens we analyzed were derived from a recent clinical trial that compared the responses of patients with recurrent platinum-resistant ovarian cancer who received carboplatin plus the DNA methyltransferase inhibitor guadecitabine or a standard-of-care chemotherapy regimen selected by the treating physician. Tumor biopsies or malignant ascites were collected from patients before treatment (day 1, cycle 1) or after treatment (after 2 cycles) for epigenomic and transcriptomic profiling using the Infinium HumanMethylation450 BeadChip (HM450). We defined 94 gene promoters that were hypomethylated significantly by guadecitabine, with 1,659 genes differentially expressed in pretreatment versus posttreatment tumors. Pathway analysis revealed that the experimental regimen significantly altered immune reactivation and DNA repair pathways. Progression-free survival correlated with baseline expression levels of 1,155 genes involved in 25 networks. In functional investigations in ovarian cancer cells, engineered upregulation of certain signature genes silenced by promoter methylation (DOK2, miR-193a, and others) restored platinum drug sensitivity. Overall, our findings illuminate how inhibiting DNA methylation can sensitize ovarian cancer cells to platinum drugs, in large part by altering gene expression patterns related to DNA repair and immune activation, with implications for improving the personalized care and survival outcomes of ovarian cancer patients.Significance: Epigenomic targeting may improve therapeutic outcomes in platinum-resistant and recurrent ovarian cancer in part by effects on DNA repair and antitumor immune responses. Cancer Res; 78(3); 631-44. ©2017 AACR.

The novel ZIP4 regulation and its role in ovarian cancer

Our RNAseq analyses revealed that ZIP4 is a top gene up-regulated in more aggressive ovarian cancer cells. ZIP4's role in cancer stem cells has not been reported in any type of cancer. In addition, the role and regulation of ZIP4, a zinc transporter, have been studied in the context of extracellular zinc transporting. Factors other than zinc with ZIP4 regulatory effects are essentially unknown. ZIP4 expression and its regulation in epithelial ovarian cancer cells was assessed by immunoblotting, quantitative PCR, or immunohistochemistry staining in human ovarian tissues. Cancer stem cell-related activities were examined to evaluate the role of ZIP4 in human high-grade serous ovarian cancer cells in vitro and in vivo. RNAi and CRISPR techniques were used to knockdown or knockout ZIP4 and related genes. Ovarian cancer tissues overexpressed ZIP4 when compared with normal and benign tissues. ZIP4 knockout significantly reduced several cancer stem cell-related activities in EOC cells, including proliferation, anoikis-resistance, colony-formation, spheroid-formation, drug-resistance, and side-population in vitro. ZIP4-expressing side-population highly expressed known CSC markers ALDH1 and OCT4. ZIP4 knockout dramatically reduced tumorigenesis and ZIP4 overexpression increased tumorigenesis in vivo. In addition, the ZIP4-expressing side-population had the tumor initiating activity. Moreover, the oncolipid lysophosphatic acid effectively up-regulated ZIP4 expression via the nuclear receptor peroxisome proliferator-activated receptor gamma and lysophosphatic acid 's promoting effects in cancer stem cell-related activities in HGSOC cells was at least partially mediated by ZIP4 in an extracellular zinc-independent manner. Our critical data imply that ZIP4 is a new and important cancer stem cell regulator in ovarian cancer. Our data also provide an innovative interpretation for the apparent disconnection between low levels of zinc and up-regulation of ZIP4 in ovarian cancer tissues.

Moving forward with actionable therapeutic targets and opportunities in endometrial cancer: NCI clinical trials planning meeting report on identifying key genes and molecular pathways for targeted endometrial cancer trials

The incidence and mortality rates from endometrial cancer are increasing. There have been no new drugs approved for the treatment of endometrial cancer in decades. The National Cancer Institute, Gynecologic Cancer Steering Committee identified the integration of molecular and/or histologic stratification into endometrial cancer management as a top strategic priority. Based on this, they convened a group of experts to review the molecular data in this disease. Here we report on the actionable opportunities and therapeutic directions identified for incorporation into future clinical trials.

A system for detecting high impact-low frequency mutations in primary tumors and metastases

Tumor complexity and intratumor heterogeneity contribute to subclonal diversity. Despite advances in next-generation sequencing (NGS) and bioinformatics, detecting rare mutations in primary tumors and metastases contributing to subclonal diversity is a challenge for precision genomics. Here, in order to identify rare mutations, we adapted a recently described epithelial reprograming assay for short-term propagation of epithelial cells from primary and metastatic tumors. Using this approach, we expanded minor clones and obtained epithelial cell-specific DNA/RNA for quantitative NGS analysis. Comparative Ampliseq Comprehensive Cancer Panel sequence analyses were performed on DNA from unprocessed breast tumor and tumor cells propagated from the same tumor. We identified previously uncharacterized mutations present only in the cultured tumor cells, a subset of which has been reported in brain metastatic but not primary breast tumors. In addition, whole-genome sequencing identified mutations enriched in liver metastases of various cancers, including Notch pathway mutations/chromosomal inversions in 5/5 liver metastases, irrespective of cancer types. Mutations/rearrangements in FHIT, involved in purine metabolism, were detected in 4/5 liver metastases, and the same four liver metastases shared mutations in 32 genes, including mutations of different HLA-DR family members affecting OX40 signaling pathway, which could impact the immune response to metastatic cells. Pathway analyses of all mutated genes in liver metastases showed aberrant tumor necrosis factor and transforming growth factor signaling in metastatic cells. Epigenetic regulators including KMT2C/MLL3 and ARID1B, which are mutated in >50% of hepatocellular carcinomas, were also mutated in liver metastases. Thus, irrespective of cancer types, organ-specific metastases may share common genomic aberrations. Since recent studies show independent evolution of primary tumors and metastases and in most cases mutation burden is higher in metastases than primary tumors, the method described here may allow early detection of subclonal somatic alterations associated with metastatic progression and potentially identify therapeutically actionable, metastasis-specific genomic aberrations.

Abstract 4347: Epigenetic targeting of DNMT1 in adipocytes inhibits high-grade serous ovarian cancer cell migration and invasion through TIMP3 upregulation

Ovarian cancer frequently metastasizes to the omentum and adipocytes play a significant role in tumor progression. As methylation levels in obese adipose tissue are increased due to increased DNMT1 levels and activity, it was of interest to test the hypothesis that inhibiting DNMT1 would reverse adipocyte methylation, alter adipokine secretion, and decrease migration and invasion of ovarian cancer cells towards adipocytes. Human adipocytes were seeded in a 24-well plate and treated with low-dose guadecitabine (100nM daily for 3 days). Ovarian cancer cells (SKOV3, Kuramochi, OVCAR4, OVCAR8) were seeded in the Boyden chamber and allowed to migrate or invade toward adipocytes for 8 and 16h, respectively. Expression of epithelial-mesenchymal transiton (EMT) markers (SLUG, FN1, TWIST1) were assessed by qRT-PCR. Adipocyte-conditioned media was used to culture ovarian cancer cells in clonogenicity assay and a human adipokine array (R&D Systems) was used to assess changes in cytokine secretion. DNMT1 protein levels in adipocytes were determined by western blot. To determine a possible mechanism, DNA and RNA from guadecitabine-treated adipocytes were subjected to methylcapture-sequencing (MBD-seq) and RNA-seq, respectively. Guadecitabine treatment of adipocytes decreased (P<0.05) migration of OVCAR4 and OVCAR8 (35% and 40%, respectively, compared to control), and a 50% decrease (P<0.05) in invasion towards adipocytes after guadecitabine treatment was observed for OVCAR4, OVCAR8, and Kuramochi cells. Expression of EMT markers SLUG, FN1 and TWIST1 decreased (P<0.05) after guadecitabine treatment. Conditioned media from guadecitabine-treated adipocytes decreased (P<0.05) clonogenic survival by 18% compared to control. Adipokine array results revealed increased secretion of LIF (lipoprotein lipase inhibitor) and TIMP3 (metalloproteinase inhibitor) after guadecitabine treatment (1.6- and 1.8-fold increase, respectively; verified by qRT-PCR). Treatment with recombinant TIMP3 (50nM) decreased invasion of OVCAR8 (63%, P<0.001) and OVCAR4 cells (73%, P<0.05). DNMT1 protein levels in adipocytes decreased in the presence of guadecitabine, despite the presence of a DNA synthesis inhibitor. Ingenuity Pathway Analysis (IPA) of MBD-seq data showed significant changes in cell-to-cell signaling and interaction pathways (FC >10; FDR <0.05). RNA-seq demonstrated increased expression of matrix metalloprotease inhibitors (THSB2, TFPI2, and NDRG4) and IPA analysis revealed a significant change in regulation of EMT pathway (FC > 1.5; FDR <0.05). Guadecitabine treatment of adipocytes alters adipokine secretion resulting in decreased cancer cell migration and invasion. In addition to direct effects on ovarian cancer cells, hypomethylating agents may impact the tumor microenvironment to alter adipokine secretion leading to decreased metastasis.

Citation Format: Jessica Tang, Fang Fang, Aaron Buechlein, Pietro Taverna, Kenneth P. Nephew. Epigenetic targeting of DNMT1 in adipocytes inhibits high-grade serous ovarian cancer cell migration and invasion through TIMP3 upregulation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4347. doi:10.1158/1538-7445.AM2017-4347

Abstract 4675: Novel combination therapy of DNA methyltransferase inhibitor guadecitabine (SGI-110) and PARP inhibitor talazoparib (BMN-673) for BRCA-proficient high-grade serous ovarian cancer

Ovarian cancer recurrence has been shown to be associated with increased DNA damage response (DDR) mediated by poly-(ADP)-ribose polymerase 1/2 (PARP1/2), which can be therapeutically targeted by PARP inhibitors (PARPi). PARPi are indicated for platinum-responsive, BRCA-mutated high-grade serous ovarian cancer, but most ovarian cancer patients have BRCA-proficient disease. Our previous studies support a role for DNA methylation in chemoresistant ovarian cancer mediated by the enzyme DNA methyltransferase 1 (DNMT1), and report on a functional role for DNMT1 in DNA damage repair. We therefore hypothesized that combining a DNMTi and PARPi will impair BRCA-mediated DDR, resulting in cytotoxicity in ovarian cancer cells. A panel of ovarian cancer cell lines (A2780, platinum sensitive, BRCA1/2-wild type; A2780-cp and HeyC2, platinum resistant, BRCA1/2-wild type; high-grade serous Kuramochi, platinum resistant, BRCA2 mutant) was examined for cell growth using colony formation assays after treatment with DNMTi guadecitabine (low dose, 20-100nm) and PARPi talazoparib (1-10nm), alone or in combination. While talazoparib alone only marginally reduced colony formation in all cell lines (dose-dependent effect), combining guadecitabine with talazoparib further decreased (P<0.05) survival at all doses examined. To focus more specifically on BRCA status, we utilized two high-grade serous ovarian cancer cell lines (“PEO”) derived from the same patient but harboring a mutant (PEO1) or wild type (PEO4) BRCA2 gene (Langdon et al, 1988; Sakai et al, 2009). Treatment with low-dose guadecitabine (20 nm, 3 days) increased (P<0.05) PARP levels (western blot analysis) as well as enzymatic activity (P<0.05; ELISA analysis), while talazoparib treatment alone increased (P<0.05) DNMT1 levels and decreased (P<0.05) PARP enzymatic activity. Treatment with guadecitabine or talazoparib alone had no effect on cell proliferation; however, combining the two drugs inhibited (>80%; P<0.05) PEO1 and PEO4 proliferation and increased (3-fold; P<0.05) apoptosis (caspase 3 cleavage) in both cell lines. Furthermore, co-administration guadecitabine (0.5mg/kg) and talazoparib (0.25mg/kg) to mice harboring BRCA2-wild type ovarian tumor xenografts decreased (p<0.05) tumor volume (>60%) and tumor weight (~70%) compared to control, respectively. In summary, combining a hypomethylating agent with a PARP inhibitor results in enhanced cytotoxicity in high-grade serous ovarian cancer cell lines harboring either wild type- or mutant-BRCA, indicating that the talazoparib-guadecitabine drug combination is effective regardless of BRCA-mediated DDR and may represent an effective treatment regimen for BRCA-related cancers.

Citation Format: Nicholas Pulliam, Pietro Taverna, John Lyons, Kenneth P. Nephew. Novel combination therapy of DNA methyltransferase inhibitor guadecitabine (SGI-110) and PARP inhibitor talazoparib (BMN-673) for BRCA-proficient high-grade serous ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4675. doi:10.1158/1538-7445.AM2017-4675

Abstract AP14: THERAPEUTIC TARGETING USING TUMOR SPECIFIC PEPTIDES INHIBITS LONG NON–CODING RNA HOTAIR ONCOGENIC ACTIVITY IN OVARIAN CANCER

PURPOSE: Most women diagnosed with advanced-stage ovarian cancer develop chemo-resistant tumor recurrence, which is uniformly fatal. Long non-coding RNAs (lncRNAs) play key roles in human diseases, including cancer. Functional studies of the lncRNA HOTAIR (HOX transcript antisense RNA) provide compelling evidence for therapeutic targeting of HOTAIR in ovarian cancer to impact chemoresistance, but targeting lncRNAs in vivo has proven to be difficult.

EXPERIMENTAL DESIGN: In the current study, we describe a peptide nucleic acids (PNA)-based approach to effectively block the ability of HOTAIR to interact with EZH2 and subsequently inhibit oncogenic HOTAIR-EZH2 activity. In order to deliver the anti-lncRNA to the acidic (pH approximately 6) microenvironment of solid tumors in vivo, PNAs were conjugated to pH-low insertion peptide (pHLIP).

RESULTS: Treatment of HOTAIR-overexpressing ovarian cancer cell lines with PNAs decreased cancer cell invasion and increased chemotherapy sensitivity. The mechanism of action of the anti-lncRNA agent correlated with reduced nuclear factor-kappaB (NF-κB) activation and decreased expression of key NF-κB target genes including matrix metalloprotease 9 and interleukin 6. PNA treatment of ALDH1A1 positive/ovarian tumor initiating cells overexpressing HOTAIR markedly decreased ALDH1A1 activity and reduced the ovarian cancer stem cell population. In mice harboring ovarian tumor xerographs and treated with pHLIP-PNA constructs, HOTAIR oncogenic activity was suppressed, ovarian tumors were resensitized to platinum, and a significant (64%) survival improvement was observed.

CONCLUSIONS: Toward developing new therapeutic approaches against chemoresistant ovarian cancer, we designed a PNA-targeting strategy for HOTAIR that effectively blocks the ability of HOTAIR to interact with EZH2 and inhibits oncogenic HOTAIR-EZH2. This first report on pHLIP-PNA targeting HOTAIR in vivo offer pre-clinical proof-of-concept and represents a possible treatment alternative for chemotherapy-resistant ovarian cancer.

Citation Format: Ali R. Özeş, Yinu Wang, Fang Fang, and Kenneth P. Nephew. THERAPEUTIC TARGETING USING TUMOR SPECIFIC PEPTIDES INHIBITS LONG NON–CODING RNA HOTAIR ONCOGENIC ACTIVITY IN OVARIAN CANCER [abstract]. In: Proceedings of the 11th Biennial Ovarian Cancer Research Symposium; Sep 12-13, 2016; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(11 Suppl):Abstract nr AP14.

Therapeutic targeting using tumor specific peptides inhibits long non-coding RNA HOTAIR activity in ovarian and breast cancer

Long non-coding RNAs (lncRNAs) play key roles in human diseases, including cancer. Functional studies of the lncRNA HOTAIR (HOX transcript antisense RNA) provide compelling evidence for therapeutic targeting of HOTAIR in cancer, but targeting lncRNAs in vivo has proven to be difficult. In the current study, we describe a peptide nucleic acids (PNA)-based approach to block the ability of HOTAIR to interact with EZH2 and subsequently inhibit HOTAIR-EZH2 activity and resensitize resistant ovarian tumors to platinum. Treatment of HOTAIR-overexpressing ovarian and breast cancer cell lines with PNAs decreased invasion and increased chemotherapy sensitivity. Furthermore, the mechanism of action correlated with reduced nuclear factor-kappaB (NF-κB) activation and decreased expression of NF-κB target genes matrix metalloprotease 9 and interleukin 6. To deliver the anti-lncRNA to the acidic (pH approximately 6) tumor microenvironment, PNAs were conjugated to pH-low insertion peptide (pHLIP). Treatment of mice harboring platinum-resistant ovarian tumor xenografts with pHLIP-PNA constructs suppressed HOTAIR activity, reduced tumor formation and improved survival. This first report on pHLIP-PNA lncRNA targeting solid tumors in vivo suggests a novel cancer therapeutic approach.

MicroRNA-335-5p and -3p synergize to inhibit estrogen receptor alpha expression and promote tamoxifen resistance

microRNAs (miRNAs) are small noncoding RNA molecules involved in the regulation of gene expression and play critical roles in human malignancies. Next-generation sequencing analysis of the MCF-7 breast cancer cell line overexpressing miR-335-5p and miR-335-3p demonstrated that the miRNA duplex repressed genes involved in the ERα signaling pathway, and enhanced resistance of MCF-7 cells to the growth inhibitory effects of tamoxifen. These data suggest that despite its conventional role in tumor suppression, the miR-335 transcript can also play an oncogenic role in promoting agonistic estrogen signaling in a cancerous setting.

Complete Transcriptome RNA-Seq

RNA-Seq is the leading technology for analyzing gene expression on a global scale across a broad spectrum of sample types. However, due to chemical modifications by fixation or degradation due to collection methods, samples often contain an abundance of RNA that is no longer intact, and the capability of current RNA-Seq protocols to accurately quantify such samples is often limited. We have developed an RNA-Seq protocol to address these key issues as well as quantify gene expression from the whole transcriptome. Furthermore, for compatibility with improved sequencing platforms, we use restructured adapter sequences to generate libraries for Illumina HiSeq, MiSeq, and NextSeq platforms. Our protocol utilizes duplex-specific nuclease (DSN) to remove abundant ribosomal RNA sequences while retaining other types of RNA for superior transcriptome profiling from low quantity input. We employ the Illumina sequencing platform, but this method is described in sufficient detail to adapt to other platforms.

Subtype-specific CpG island shore methylation and mutation patterns in 30 breast cancer cell lines

Background

Aberrant epigenetic modifications, including DNA methylation, are key regulators of gene activity in tumorigenesis. Breast cancer is a heterogeneous disease, and large-scale analyses indicate that tumor from normal and benign tissues, as well as molecular subtypes of breast cancer, can be distinguished based on their distinct genomic, transcriptomic, and epigenomic profiles. In this study, we used affinity-based methylation sequencing data in 30 breast cancer cell lines representing functionally distinct cancer subtypes to investigate methylation and mutation patterns at the whole genome level.

Results

Our analysis revealed significant differences in CpG island (CpGI) shore methylation and mutation patterns among breast cancer subtypes. In particular, the basal-like B type, a highly aggressive form of the disease, displayed distinct CpGI shore hypomethylation patterns that were significantly associated with downstream gene regulation. We determined that mutation rates at CpG sites were highly correlated with DNA methylation status and observed distinct mutation rates among the breast cancer subtypes. These findings were validated by using targeted bisulfite sequencing of differentially expressed genes (n=85) among the cell lines.

Conclusions

Our results suggest that alterations in DNA methylation play critical roles in gene regulatory process as well as cytosine substitution rates at CpG sites in molecular subtypes of breast cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12918-016-0356-2) contains supplementary material, which is available to authorized users.

Abstract 4024: Epigenetic priming potentiates immune checkpoints inhibitors in ovarian cancer

Background: Ovarian cancer (OC) progression is accompanied by the establishment of stable and transcriptionally repressive epigenetic modifications. An important mechanism of immune evasion is represented by epigenetic silencing of tumor antigens (NY-ESO-1, Muc16 and MAGE). We hypothesize that by reversing DNA methylation, DNA methyl transferase inhibitors (DNMTIs) restore the expression of such antigens, potentiating anti-tumor immune response. The targeting of immune checkpoints regulated by programmed cell death protein-1(PD-1) signaling represents a novel therapeutic strategy in cancer, including in OC. Here we set out to measure the anti-tumor effects of epigenetic priming in combination with PD-1/PDL-1 blockade in OC preclinical models.

Methods: The ID8 intraperitoneal (ip) immunocompetent syngeneic mouse model was used to measure the effects of the novel DNMTI guadecitabine (SGI-110, Astex Pharmaceuticals Inc) and PDL1 blockade. The experimental groups consisted of non-specific IgG (control), guadecitabine 2mg/m2 sq bi-weekly, murine anti-PDL1 inhibitory antibody (10mg/kg) bi-weekly and combination of guadecitabine with anti-PDL1 antibody (n = 6 mice/group, 3 week treatment). Immune cells collected from the ascites and spleens of tumor bearing mice were either directly processed or co-cultured with ID8 cells for 48 hours. Cells were immuno-phenotyped by flow cytometry. In OC cells treated with guadecitabine, changes in gene expression were analyzed by real time-PCR.

Results: In ID8 tumors bearing mice, the combination of PDL1 blockade with guadecitabine significantly decreased primary tumor formation (P<0.05) and malignant ascites accumulation (P<0.0001) compared with the control group. Treatments were well tolerated without detectable weight changes attributable to toxicity. CD8+ cell fractions expressing the exhaustion markers (PD1+ or CTL4+) isolated from the ascites and spleens of control mice were diminished by guadecitabine, PD-L1 inhibitory antibody, and the combination treatment. Guadecitabine and the combination regimen increased CD8+/MHC1+ and CD8+/CD40+ cell populations. Treatment with DNMTIs significantly increased the expression of tumor antigens Muc16, Mage A2, A11, and NY-ESO 1 (p<0.01) in several OC cell lines.

Conclusions: Guadecitabine in combination with anti-PDL1 antibody induced striking anti-tumor effects in an immunocompetent OC syngeneic model by activating cytotoxic T-cells. These data support clinical strategies utilizing epigenetic priming using DNMTI in combination with immune checkpoints inhibitors.

Citation Format: Yu Qing, Salvatore Condello, Katie J. Meyer, Andrea Caperell-Grant, Kenneth P. Nephew, Daniela Matei. Epigenetic priming potentiates immune checkpoints inhibitors in 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 4024.

Abstract 950: Bistable switching of c-KIT by estrogen-mediated ceRNA and epigenetic silencing of miR-193a predicts survival in ovarian cancer

Ovarian cancer is one of the most lethal cancers in the female reproductive system. Our previous study has shown that ovarian cancer may be initiated by ovarian cancer initiating cells (OCIC) characterized by the surface antigen CD44 and c-KIT (CD117). Previous study also suggested that long term treatment of estrogen such as hormonal replacement therapy (HRT) may increase the risk of ovarian cancer, however the role of estrogen in ovarian carcinogenesis is still controversial. To unravel this complexity, we propose a mathematical model to explore how the ER signaling pathway contribute to c-KIT expression during ovarian carcinogenesis: one through a ceRNA competition of an ER target,E2F6 and c-KIT for their targeted miRNA, miR-193a; second by binding of E2F6 protein, in association with the polycomb complex, to the promoter of miR-193a to downregulate miR-193a transcription by epigenetic modifications. Our model found that epigenetic silencing of miR-193a generates a bistable switching of c-KIT during ovarian carcinogenesis based on the level of EZH2. To confirm our results, we performed ectopic expression of miR-193a and 3’UTR luciferase in ovarian cancer cell lines and confirmed that E2F6 and c-KIT are the targets of miR-193a. Importantly, treatment of E2 or bisphenol A (BPA) resulted in the up-regulation of E2F6 and c-kit mRNA in IOSE cells in which no or low methylation at the promoter CpG island of miR-193a was found. On the contrary, promoter hypermethylation of miR193a could be observed in miR-193a-underexpressed CP70 ovarian cancer cells but not in HeyC2 cells which showed similar expression level of miR-193a as in IOSE cells. Treatment of demethylating agent (5azaDC) or EZH2 inhibitor (GSK343) resulted in a reexpression of miR-193a in CP70 ovarian cancer cells. Overexpression of miR-193a inhibited tumor growth in vitro and in an animal model. Further ChIP-PCR assay also found that open chromatin mark H3K4me3 was enriched in the promoter region of miR-193a in HeyC2 but not in CP70 cells. On the contrary, repressive chromatin marks H3K9me3 and H3K27me3 were only enriched in CP70 cells. Clinically, ovarian cancer patients (n = 109) with higher promoter methylation of miR-193a were associated with poor survival (p>0.05). Additional analysis of the TCGA ovarian cancer dataset demonstrated that ovarian cancer patients with low expression of EZH2, a polycomb-group protein, showed positive correlation (p<0.05) between E2F6 and c-KIT which resembles the ceRNA phenomenon between these two mRNAs. Importantly, ovarian cancer patients with low expression of EZH2 tended to have lower expression of c-KIT. In conclusion, our mathematical model and experimental data suggests that miR-193a can be epigenetically regulated by both ceRNA and promoter methylation. Simultaneous EZH2 inhibition and anti-estrogen therapy can constitute an effective combined therapeutic strategy against ovarian cancer.

Citation Format: Frank Hsueh-Che Cheng, Baltazar D. Aguda, Hon-Yi Lin, Je-Chiang Tsai, Marek Kochanczyk, Ru-Inn Lin, Jora M. J. Lin, Gary C. W. Chen, Cheng-Chang Chang, Hung-Cheng Lai, Kenneth P. Nephew, Tzy-Wei Hwang, Michael W. Y. Chan. Bistable switching of c-KIT by estrogen-mediated ceRNA and epigenetic silencing of miR-193a predicts survival in 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 950.

Long-range regulators of the lncRNA HOTAIR enhance its prognostic potential in breast cancer

Predicting response to endocrine therapy and survival in oestrogen receptor positive breast cancer is a significant clinical challenge and novel prognostic biomarkers are needed. Long-range regulators of gene expression are emerging as promising biomarkers and therapeutic targets for human diseases, so we have explored the potential of distal enhancer elements of non-coding RNAs in the prognostication of breast cancer survival. HOTAIR is a long non-coding RNA that is overexpressed, promotes metastasis and is predictive of decreased survival. Here, we describe a long-range transcriptional enhancer of the HOTAIR gene that binds several hormone receptors and associated transcription factors, interacts with the HOTAIR promoter and augments transcription. This enhancer is dependent on Forkhead-Box transcription factors and functionally interacts with a novel alternate HOTAIR promoter. HOTAIR expression is negatively regulated by oestrogen, positively regulated by FOXA1 and FOXM1, and is inversely correlated with oestrogen receptor and directly correlated with FOXM1 in breast tumours. The combination of HOTAIR and FOXM1 enables greater discrimination of endocrine therapy responders and non-responders in patients with oestrogen receptor positive breast cancer. Consistent with this, HOTAIR expression is increased in cell-line models of endocrine resistance. Analysis of breast cancer gene expression data indicates that HOTAIR is co-expressed with FOXA1 and FOXM1 in HER2-enriched tumours, and these factors enhance the prognostic power of HOTAIR in aggressive HER2+ breast tumours. Our study elucidates the transcriptional regulation of HOTAIR, identifies HOTAIR and its regulators as novel biomarkers of patient response to endocrine therapy and corroborates the importance of transcriptional enhancers in cancer.

Dual regulation by microRNA-200b-3p and microRNA-200b-5p in the inhibition of epithelial-to-mesenchymal transition in triple-negative breast cancer

Epithelial to mesenchymal transition (EMT) involves loss of an epithelial phenotype and activation of a mesenchymal one. Enhanced expression of genes associated with a mesenchymal transition includes ZEB1/2, TWIST, and FOXC1. miRNAs are known regulators of gene expression and altered miRNA expression is known to enhance EMT in breast cancer. Here we demonstrate that the tumor suppressive miRNA family, miR-200, is not expressed in triple negative breast cancer (TNBC) cell lines and that miR-200b-3p over-expression represses EMT, which is evident through decreased migration and increased CDH1 expression. Despite the loss of migratory capacity following re-expression of miR-200b-3p, no subsequent loss of the conventional miR-200 family targets and EMT markers ZEB1/2 was observed. Next generation RNA-sequencing analysis showed that enhanced expression of pri-miR-200b lead to ectopic expression of both miR-200b-3p and miR-200b-5p with multiple isomiRs expressed for each of these miRNAs. Furthermore, miR-200b-5p was expressed in the receptor positive, epithelial breast cancer cell lines but not in the TNBC (mesenchymal) cell lines. In addition, a compensatory mechanism for miR-200b-3p/200b-5p targeting, where both miRNAs target the RHOGDI pathway leading to non-canonical repression of EMT, was demonstrated. Collectively, these data are the first to demonstrate dual targeting by miR-200b-3p and miR-200b-5p and a previously undescribed role for microRNA processing and strand expression in EMT and TNBC, the most aggressive breast cancer subtype.

Abstract A70: Epigenome and genome alterations in platinum resistant ovarian tumors

Purpose: Epigenetic changes, particularly in DNA methylation, have been implicated in acquired resistance to platinum in ovarian cancer (OC). The goal of the current study was to analyze and integrate global RNA expression and DNA methylation profiles of platinum resistant tumors compared to untreated, platinum-sensitive ovarian tumors, as well as to measure genomic and epigenomic changes induced by guadecitabine (SGI-110) in tumors.

Methods: An ongoing phase I/II multi-institutional clinical trial uses the novel DNA methyltransferase (DNMT) inhibitor guadecitabine to re-sensitize recurrent platinum resistant OC to carboplatin. Patients enrolled in this trial had recurrent platinum resistant OC. Tumor biopsies were collected at baseline and after two cycles of guadecitabine administered daily for 5 days at a low (30mg/m2) dose (28 days per cycle). RNA and DNA were extracted from 48 and 57 baseline tumors and analyzed for next generation sequencing approaches to interrogate transcriptomes (RNA-seq) and methylomes (Infinium Human Methylation450 (HM450) arrays), respectively. Differential gene expression and DNA methylation profiles were generated and used for Ingenuity Pathway Analysis (IPA) to identify the top altered pathways in response to guadecitabine. Expression of DNMTs was examined by real-time RT-PCR and immunohistochemistry. LINE1 methylation and promoter methylation of selected genes (MAGE-A2, MAGE-A3, MAGE-A11, NY-ESO, RASSF1, MLH1, and HOXA11) were quantified by pyrosequencing before and after guadecitabine treatment (n=12 paired samples).

Results: Analysis of a limited number of paired samples before and after treatment (n=8) revealed significant changes in global gene expression profiles induced by guadecitabine, with 960 altered genes representing immunopathway enrichment including cytokine production in macrophages and T helper cells by IL-17A and IL-17F, granulocyte /agranulocyte adhesion and inflammation, IL-8 signaling, p38 MAPK signaling, cAMP-mediated signaling, and innate immunity. Epigenetic profiling using HM450 revealed extensive methylation changes when comparing recurrent platinum resistant ovarian tumors (n=42) to primary, untreated ovarian cancer specimens analyzed as part of the TCGA project (n=10). Six hundred and four promoters were significantly differentially methylated (adjusted p<0.05, absolute methylation changes β>0.2), among which, 498 and 106 were hypermethylated or hypomethylated respectively in recurrent platinum resistant ovarian tumors. IPA analysis of baseline tumor transcriptome and methylome demonstrated significant enrichment in a wide range of pathways associated with cancer, stem cells, inflammation and the immune system. DNMT1, 3A, and 3B mRNA levels in the tumors were highly variable (n=19). Analysis of a limited number of paired samples (n=7) revealed no significant changes in global methylation or in DNMT expression levels induced by treatment with guadecitabine (adjusted p>0.05). However, the DNMT inhibitor induced significant methylome alterations in selected patients. Significant hypomethylation of MAGE-A3 and MAGE–A11 promoters (p<0.05) was detected. Correlations between methylation changes and clinical outcomes are being explored.

Conclusions: These data suggest that treatment with the DNMT inhibitor guadecitabine induces a reactivation of immune responses in human OC. Correlations between methylation changes and expression profiles are being explored.

Citation Format: Fang Fang, Horacio Cardenas, Dave Miller, Aaron Buechlein, Qing Yu, Yunlong Liu, Guanglong Jiang, Pietro Taverna, Harold Keer, Doug Rusch, Daniela Matei, Kenneth P. Nephew. Epigenome and genome alterations in platinum resistant ovarian tumors. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr A70.

Abstract A57: Platinum induces IL-6-signaling mediated activation of ALDH1A1 and enriches the cancer stem cell population in ovarian cancer

Purpose: While chemotherapy may succeed initially at decreasing the number of ovarian cancer (OC) cells, it leaves behind tumors enriched in ovarian cancer stem cells (OCSCs), which most likely drive chemoresistance and tumor relapse. An emerging model indicates that non-OCSCs may dedifferentiate and acquire stem cell properties under certain circumstances. Recent studies in OC implicate a critical role for aberrant cytokine interleukin-6 (IL-6) secretion and the IL-6 signaling pathway may play a critical role in converting non-CSCs to CSC. In the current study, we investigated the mechanism contributing to OCSC enrichment after platinum treatment in vivo. We hypothesize that platinum-induced IL-6 secretion activates STAT3 signaling-mediated expression of the cancer stem cell marker ALDH1A1, resulting in CSC enrichment. In addition, based on our previous study in OCSCs (Wang et al., 2014, Cancer Res.), we sought to examine the mechanism by which guadecitabine (SGI-110), a second generation hypomethylating agent HMA, inhibits OCSCs in OC xenograft residuals after platinum treatment.

Methods: OC cells (OVCAR4 and A2780) were cultured alone or co-cultured with normal omental fibroblasts (NOFs) or guadecitabine (100nM, 3days)-treated NOFs in the starving condition for 24h and then treated with 3h cisplatin (CDDP; respective IC50 doses of 27.4 and 14.7μM), guadecitabine, IL-6 (100ng/ml), neutralizing antibody (Nab) against IL-6 (IL-6-Nab, 200ng/mL) or IL-6+IL-6-Nab. IL-6 secretion levels were measured by ELISA. FACS was used to analyze OCSC population marked as aldehyde dehydrogenase (ALDH)+ cells, and western blot was used to examine ALDH1A1 and pSTAT3 levels in cells treated as described above. An ALDH1A1 promoter-luciferase reporter (pGL3-ALDH1A1-Luc; -1 to -1031) assay was used to determine whether IL-6 transactivates ALDH1A1 expression in OC cells. OC cell migration under the described conditions was determined by transwell migration assays.

Results: We found that CDDP induced (P<0.05) IL-6 secretion by OCs up to 48h post-treatment and up to 96h by NOFs or by co-cultured cells, suggesting a role of the tumor microenvironment in platinum-induced IL-6 secretion. Guadecitabine inhibited (P<0.05) CDDP-induced IL-6 secretion by NOFs alone or in co-culture with OVCAR4, suggesting an inhibitory role of the HMA on IL-6 signaling. By assaying FACS sorted ALDH+/- cells, we determined that ALDH+ cells express increased (P<0.05) levels of the IL-6 receptor and secrete higher (P<0.05) levels of IL-6 in the conditioned media compared to ALDH- cells. Treatment of OC cells with IL-6 enriched the percentage of ALDH+, which was inhibited by IL-6-Nab. Luciferase assay results revealed that IL-6 transactivated (p<0.05) ALDH1A1 reporter gene expression in ALDH- cells, which was blocked by IL-6-Nab. Further, we observed that IL-6- or CDDP-treated OC cells increased (P<0.05) ALDH1A1 and pSTAT3 protein expression, and guadecitabine treatment inhibited (P<0.05) expression of ALDH1A1 and pSTAT3 in OCs. ALDH+ cells showed greater migration potential than ALDH- cells, and guadecitabine inhibited (P<0.05) migration of both ALDH+ and ALDH- cells. Guadecitabine, alone or combination with IL-6-Nab, inhibited (P<0.05) CDDP-induced OVCAR4 migration in co-culture with NOFs.

Conclusion: Our data indicate that IL-6 is a potent regulator of ALDH1A1 expression and the OCSC phenotype and further suggest an inhibitory effect of guadecitabine on the conversion of non-OCSCs to OCSCs. The data support a role for IL-6 in OCSC enrichment after platinum treatment and suggest that a combination approach of IL-6 neutralizing antibody with guadecitabine could represent a novel maintenance strategy after chemotherapy for eradicating OCSCs and preventing tumor recurrence.

Citation Format: Yinu Wang, Anirban Kumar Mitra, Kenneth P. Nephew. Platinum induces IL-6-signaling mediated activation of ALDH1A1 and enriches the cancer stem cell population in ovarian cancer. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr A57.

Identification of novel immunomodulatory tumor biology through comprehensive characterization of a metastases-specific epigenome in patients with metachronous primary and metastatic urothelial carcinoma (UC) tumor pairs

452

Background: The Cancer Genome Atlas project identified a distinct cluster of hypermethylated muscle-invasive UC tumors in one third of patients. It is unknown if this epigenetic biology persists or changes in UC metastases. The present study aimed to identify uniquely hypermethylated regions in UC metastases compared to their matched primary tumors. Methods: UC patients with paired formalin fixed paraffin embedded tissue samples ( > 75% tumor) from primary and metachronous metastatic tumors were identified. DNA methylation was analyzed on the Illumina HiSeq platform by double-enzyme reduced representation bisulfite sequencing (dRRBS). Results were analyzed by BS-seq within BSmooth open source software. Alignment and methylation estimation was done using Bismark open source software. CpG regions with coverage < 2 in more than 66% of samples were removed to reduce false positive results. Differentially methylated regions (DMRs) in metastases compared to primary tumors were determined by paired t-test. Gene set enrichment analysis (GSEA) of the top 5% DMRs was performed utilizing multiple gene set collections including c7IMMUNO. A false discovery rate of < 10% defined significant DMRs. Results: 15 UC primary/metachronous metastases pairs were analyzed. After filtering for low coverage, 1,781,762 loci remained for analysis. After merging loci within 2500 bp of each other, the top 5% DMRs resulted in 18,452 DMRs. GSEA including the c7IMMUNO gene set identified multiple previously undescribed hypermethylated genes modulating immune function through TGF-beta and Treg signaling including: TGFBR2, TGFBR3, SMAD1, SMAD3, SMAD4, BACH1, BACH2, and VDR all q < 0.05. Conclusions: We identified numerous genes with immunomodulatory functions significantly hypermethylated in UC metastases compared to their matched primary tumors. Our findings provide rationale to examine epigenetic approaches as a means to improve clinical outcomes of UC patients treated with immunotherapy. Our small sample size limits definitive conclusions and warrants validation in independent data sets.

Abstract B2-09: A systems biology approach to understanding estrogen responsiveness in breast cancer cells using the MCF7 model

Estrogen receptor alpha (ER) is expressed in 70% of breast cancers and is critical for breast cancer cell proliferation, differentiation, and apoptosis. ER functions primarily as a nuclear transcription factor that dimerizes upon binding of the natural ligand, 17beta estradiol (E2). ER is a potent regulator of gene expression, altering the transcriptome, and ultimately both the proteome and metabolome. In the clinic, ER+ tumors are often treated with antiestrogens or aromatase inhibitors. However, resistance to these endocrine therapies is common, and there is an urgent need to understand how estrogen signaling contributes to the malignancy of breast cancer cells. The MCF7 ER+ breast cancer cell line is a commonly used cell model to study estrogen responsiveness in ER+ breast cancers. However, the field lacks a clear and detailed description of all the changes that occur in response to E2 by time and dose in MCF7 cells. Additionally, there is a great need to obtain a consistent view of the estrogen-regulated gene set, resolve the disconnections among epigenetics regulation of estrogen signaling and protein phosphoproteomics, and provide reliable metabolomics data sets for MCF7 cells. In this multi-institutional project, we have generated multi-omics data and cell cycle profile for MCF7 cells treated with 1 pM and 1 nM of E2 for 26-time points, 0 to 72 h. MCF7 cell line was obtained from American Type Culture Collection (ATCC), fingerprinted and confirmed for E2 and Tamoxifen sensitivity prior to omics studies. Moreover, ER expression (basal and with E2 stimulation) was determined using Western blotting and qPCR. Omics data generated include: RNA-seq (coding and non-coding), reverse phase protein array (RPPA; proteins and phospho-proteins), methylome analysis, cell cycle analysis and metabolomics (metabolites). Using our data sets, comprehensive responses to physiologically relevant E2 concentrations, including both rapid and long-term E2 responses, can be determined. Our data were processed using current best practices and the time trends for the 1 pM and 1 nM doses of E2 were assessed via linear models separately for the various omics features. Global differences between samples were further assessed via principal components analysis. The features which showed the most significant differences in time trends between the two dose groups were visualized as heatmaps. The objective of this study is to provide our data and discoveries as a common resource for the systems biology centers and the broader research community. A multi-dimensional dataset such as our will enable the development of dynamic network model(s) to interrogate estrogen signaling, from nucleic acids to proteins, with changes in the MCF7 metabolome.

Citation Format: Ayesha N. Shajahan-Haq, Lang Li, Yunlong Liu, Lu Jin, David F. Miller, Jay Pilrose, Amrita K. Cheema, Simina M. Boca, Krithika Bhuvaneshwar, Subha Madhavan, Robert Clarke, Kenneth P. Nephew. A systems biology approach to understanding estrogen responsiveness in breast cancer cells using the MCF7 model. [abstract]. In: Proceedings of the AACR Special Conference on Computational and Systems Biology of Cancer; Feb 8-11 2015; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(22 Suppl 2):Abstract nr B2-09.

Rethinking ovarian cancer II: reducing mortality from high-grade serous ovarian cancer

High-grade serous ovarian cancer (HGSOC) accounts for 70-80% of ovarian cancer deaths, and overall survival has not changed significantly for several decades. In this Opinion article, we outline a set of research priorities that we believe will reduce incidence and improve outcomes for women with this disease. This 'roadmap' for HGSOC was determined after extensive discussions at an Ovarian Cancer Action meeting in January 2015.