- Email: [email protected]
65 Pancreatic Cancer Therapies
S16
european journal of cancer 48, suppl. 5 (2012) S13–S19
65 Pancreatic Cancer Therapies D. Tuveson1 . 1 Cancer Research UK, Cambridge Research Institute, Cambridge, United Kingdom Pancreatic cancer is refractory to current chemotherapy and is responsible for the deaths of over 250,000 patients world-wide per annum. Explorations of therapeutic response in a Mus Musculus model of pancreatic ductal adenocarcinoma (PDA) have yielded potential mechanisms of disease resistance, and also offer the opportunity to thereby overcome such barriers. We recently reported that primary pancreatic ductal adenocarcinoma (PDA) tumours in Mus Musculus and Homo Sapiens contain a deficient and compressed vasculature that is embedded in a dense stromal matrix, and proposed that this may impede effective delivery of chemotherapeutics and other agents with limited bioavailability. Indeed, stromal depletion with a hedgehog pathway inhibitor induced a reactive angiogenesis in the tumour and correspondingly increased chemotherapy delivery and response. These studies also explored the role of traditional xenograft models of pancreatic cancer, and revealed that xenograft tumors were well vascularised and lacked tumor stroma − potentially explaining the increased sensitivity of xenografts to chemotherapy. We have now extended our observation to other agents that target the tumour microenvironment to increase the efficacy of gemcitabine. One of these, nab-Paclitaxel, increases gemcitabine levels not by enhancing drug delivery, but rather by targeting cytidine deaminase for destruction. Additionally, gamma secretase inhibition cooperates with gemcitabine to cause hypoxic necrosis and response. Several of our observations serve as the basis of clinical trials to probe the relevance of such findings in patients. 66 Proffered Paper: PTEN Phosphorylation by Fibroblast Growth Factor Receptors and SRC Mediates Resistance to Epidermal Growth Factor Receptor Inhibitors in Glioblastoma F. Furnari1 , T. Fenton2 , H. Zhou2 , S. Marie3 , P. Mischel4 , W. Cavenee5 . 1 Ludwig Insitute-UCSD, Pathology, La Jolla, USA, 2 Ludwig Insitute-UCSD, La Jolla, USA, 3 University of Sao Paulo, Sao Paulo, Brazil, 4 University of California Los Angeles, Los Angeles, USA, 5 Ludwig Institute-UCSD, Medicine, La Jolla, USA Background: Glioblastoma multiforme (GBM) is the most aggressive of the astrocytic malignancies and the most common intracranial tumor in adults. Although the epidermal growth factor receptor (EGFR) is overexpressed and/or mutated in at least 50% of GBM cases and is required for tumor maintenance in animal models, EGFR inhibitors have thus far failed to deliver significant responses in GBM patients. Material and Methods: Mass spectrometry was used to identify PTEN tyrosine phosphorylation sites and a phospho-specific antibody against one such site (Y240), was developed. This antibody was used to study PTEN tyrosine phosphorylation in cell lines and primary tumor samples from GBM patients. Wild type PTEN and a non-phosphorylated tyrosine 240 to phenylalanine (Y240F) mutant were used to define the role of Y240 phosphorylation in promoting EGFR tyrosine kinase inhibitor (TKI) resistance. Results: One inherent TKI resistance mechanism in GBM is the co-activation of multiple receptor tyrosine kinases (RTKs) which generates redundancy in activation of Phosphoinositide-3 -Kinase (PI3K) signaling. Here we identified a novel mechanism by which fibroblast growth factor receptors (FGFRs) and src family kinases (SFKs) impact on PI3K signaling in GBM by phosphorylating PTEN at a conserved tyrosine residue, Y240. Phosphorylation of Y240 was associated with shortened overall survival and resistance to EGFR TKIs in GBM patients, and played an active role in mediating resistance to EGFR inhibition in vitro. Experimentally, a non-phosphorylated Y240F mutant allele of PTEN potently sensitized cells expressing a constitutively active mutant of EGFR (EGFRvIII) to erlotinib. In contrast, activation of FGFR signaling promoted resistance to erlotinib in GBM cells expressing wild type PTEN, concordant with phosphorylation of PTEN and activation of downstream signaling. Conclusions: Our findings identify a novel signaling connection between FGFRs and PTEN and provide a mechanistic link between PTEN regulation and drug resistance, suggesting that blocking PTEN phosphorylation by suppression of SRC and/or FGFR activity represents a potential strategy to re-sensitize tumors to EGFR inhibitors.
Monday 9 July 2012
regimens, ultimately achieving long term control of cancer. While promising, the analysis of CTCs is complicated by significant technological hurdles, including very rare cell detection within a complex fluid, high throughput imaging of cells expressing variable markers, and molecular analysis of incompletely purified heterogeneous cell populations. To address these challenges, our team of engineers, molecular biologists and clinicians has devised a series of microfluidic devices capable of capturing CTCs with high efficiency, optimized parameters for semi-automated imaging and quantitation, and initiated molecular genetic and digital gene expression analyses of captured cells. In studying lung, prostate, pancreatic and breast cancers, we find that CTCs can be detected in some localized invasive cancers as well as in metastastic cases. The molecular markers identified in CTCs are highly correlated with those of simultaneously sampled tumors, but may occasionally differ from those of primary tumors resected years before the development of metastatic disease. Certain features, such as proliferative index of CTCs (measured by Ki67 staining) differ dramatically between different clinical stages of disease. Mutations conferring acquired resistance to targeted agents can be detected within CTCs and their prevalence in the CTC population increases in concert with the advent of clinical drug resistance. Finally, RNA sequencing approaches may be used to generate digital expression profiles of CTCenriched populations, providing confirmation as to their cell of origin, as well as identifying potential transcript that are upregulated in CTCs and may contribute to their metastatic propensity. Together, the molecular analysis of CTCs offers the potential to monitor drug responses in clinical trials, and also to identify potential new therapeutic targets aimed at suppressing cancer metastasis.
Monday 9 July 2012
12:15−13:00
FEBS Lecture: Drug Development 68 Targeted Cancer Therapy Development A. Ullrich1 . 1 Max-Planck Institute for Biochemistry, Department of Molecular Biology, Martinsried, Germany For the past years we have investigated various aspects of signaling systems in tumor cells in order to identify critical switch points in the pathophysiological process that results in malignancy. These efforts aim at the selective blockade of abnormal, disease-promoting signaling mechanisms by monoclonal antibodies, or small molecule kinase inhibitors. This strategic approach began with the cloning of the EGF receptor cDNA and the related receptor HER-2/neu and translated the animal oncogene concept into target-directed personalized therapy of human cancer. This work yielded the first specific oncogene target-based, FDA-approved (1998) personalized, therapeutic agent, “Herceptin”, for the treatment of metastatic breast cancer of a subgroup of individually defined patients. Earlier and subsequent “targetdriven drug development” efforts that employed various genomic analysis strategies led to the cancer therapies that are based on EGFR, HER3, FGFR4, Axl/Ufo and Flk-1/VEGFR2 as critical signaling elements in tumor progression. The latter served, in cooperation with SUGEN Inc./Pharmacia/Pfizer, as basis for the development of SU11248/Sunitinib. The drug discovery process that started with Herceptin and led to Sunitinib represents a prototypical example for the adaptation of cancer therapeutics from highly specific to multi-targeted drugs. While all novel cancer therapies target genetic alterations in tumor tissues innovative strategies are aimed at investigating the contribution of germ line determinants of the patient to disease progression and therapy response. One example is the common polymorphism at codon position 388 in the human FGFR4 gene of which the Arg388 allele represents a target for the development of individual genotype-dependent cancer therapy development. Current findings and their consequences for patient-specific cancer therapy will be presented.
Monday 9 July 2012
14:30−15:15
Ramon Areces Foundation Lecture: Non Coding RNA
67 Molecular Characterization of Circulating Tumour Cells D. Haber1 . 1 Massachusetts General Hospital Cancer Center, MGH Cancer Center, Boston MA, USA Circulating tumor cells (CTCs) are shed into the bloodstream from primary epithelial cancers and their metastatic deposits. Although extraordinarily rare among normal blood components, they provide a unique opportunity to noninvasively sample tumor cells, monitor their response to therapy and potentially predict the emergence of drug resistance. Nowhere is this more critical than in the new field of targeted cancer therapies, where continuous analysis of tumor genotypes may allow rational adjustments of treatment
69 The ceRNA Hypothesis and the Non-coding Revolution in Cancer Research and Therapy P. Pandolfi1 . 1 Beth Israel Deaconess Cancer Center and Harvard Medical School, Boston, MA, USA The central dogma of molecular biology, as proposed by Francis Crick, demonstrates that genetic information is transferred from DNA in our genomes to the generation of functional proteins, through a messenger RNA (mRNA) intermediate. This suggests that the key function of each mRNA is to encode for protein.
european journal of cancer 48, suppl. 5 (2012) S13–S19
65 Pancreatic Cancer Therapies D. Tuveson1 . 1 Cancer Research UK, Cambridge Research Institute, Cambridge, United Kingdom Pancreatic cancer is refractory to current chemotherapy and is responsible for the deaths of over 250,000 patients world-wide per annum. Explorations of therapeutic response in a Mus Musculus model of pancreatic ductal adenocarcinoma (PDA) have yielded potential mechanisms of disease resistance, and also offer the opportunity to thereby overcome such barriers. We recently reported that primary pancreatic ductal adenocarcinoma (PDA) tumours in Mus Musculus and Homo Sapiens contain a deficient and compressed vasculature that is embedded in a dense stromal matrix, and proposed that this may impede effective delivery of chemotherapeutics and other agents with limited bioavailability. Indeed, stromal depletion with a hedgehog pathway inhibitor induced a reactive angiogenesis in the tumour and correspondingly increased chemotherapy delivery and response. These studies also explored the role of traditional xenograft models of pancreatic cancer, and revealed that xenograft tumors were well vascularised and lacked tumor stroma − potentially explaining the increased sensitivity of xenografts to chemotherapy. We have now extended our observation to other agents that target the tumour microenvironment to increase the efficacy of gemcitabine. One of these, nab-Paclitaxel, increases gemcitabine levels not by enhancing drug delivery, but rather by targeting cytidine deaminase for destruction. Additionally, gamma secretase inhibition cooperates with gemcitabine to cause hypoxic necrosis and response. Several of our observations serve as the basis of clinical trials to probe the relevance of such findings in patients. 66 Proffered Paper: PTEN Phosphorylation by Fibroblast Growth Factor Receptors and SRC Mediates Resistance to Epidermal Growth Factor Receptor Inhibitors in Glioblastoma F. Furnari1 , T. Fenton2 , H. Zhou2 , S. Marie3 , P. Mischel4 , W. Cavenee5 . 1 Ludwig Insitute-UCSD, Pathology, La Jolla, USA, 2 Ludwig Insitute-UCSD, La Jolla, USA, 3 University of Sao Paulo, Sao Paulo, Brazil, 4 University of California Los Angeles, Los Angeles, USA, 5 Ludwig Institute-UCSD, Medicine, La Jolla, USA Background: Glioblastoma multiforme (GBM) is the most aggressive of the astrocytic malignancies and the most common intracranial tumor in adults. Although the epidermal growth factor receptor (EGFR) is overexpressed and/or mutated in at least 50% of GBM cases and is required for tumor maintenance in animal models, EGFR inhibitors have thus far failed to deliver significant responses in GBM patients. Material and Methods: Mass spectrometry was used to identify PTEN tyrosine phosphorylation sites and a phospho-specific antibody against one such site (Y240), was developed. This antibody was used to study PTEN tyrosine phosphorylation in cell lines and primary tumor samples from GBM patients. Wild type PTEN and a non-phosphorylated tyrosine 240 to phenylalanine (Y240F) mutant were used to define the role of Y240 phosphorylation in promoting EGFR tyrosine kinase inhibitor (TKI) resistance. Results: One inherent TKI resistance mechanism in GBM is the co-activation of multiple receptor tyrosine kinases (RTKs) which generates redundancy in activation of Phosphoinositide-3 -Kinase (PI3K) signaling. Here we identified a novel mechanism by which fibroblast growth factor receptors (FGFRs) and src family kinases (SFKs) impact on PI3K signaling in GBM by phosphorylating PTEN at a conserved tyrosine residue, Y240. Phosphorylation of Y240 was associated with shortened overall survival and resistance to EGFR TKIs in GBM patients, and played an active role in mediating resistance to EGFR inhibition in vitro. Experimentally, a non-phosphorylated Y240F mutant allele of PTEN potently sensitized cells expressing a constitutively active mutant of EGFR (EGFRvIII) to erlotinib. In contrast, activation of FGFR signaling promoted resistance to erlotinib in GBM cells expressing wild type PTEN, concordant with phosphorylation of PTEN and activation of downstream signaling. Conclusions: Our findings identify a novel signaling connection between FGFRs and PTEN and provide a mechanistic link between PTEN regulation and drug resistance, suggesting that blocking PTEN phosphorylation by suppression of SRC and/or FGFR activity represents a potential strategy to re-sensitize tumors to EGFR inhibitors.
Monday 9 July 2012
regimens, ultimately achieving long term control of cancer. While promising, the analysis of CTCs is complicated by significant technological hurdles, including very rare cell detection within a complex fluid, high throughput imaging of cells expressing variable markers, and molecular analysis of incompletely purified heterogeneous cell populations. To address these challenges, our team of engineers, molecular biologists and clinicians has devised a series of microfluidic devices capable of capturing CTCs with high efficiency, optimized parameters for semi-automated imaging and quantitation, and initiated molecular genetic and digital gene expression analyses of captured cells. In studying lung, prostate, pancreatic and breast cancers, we find that CTCs can be detected in some localized invasive cancers as well as in metastastic cases. The molecular markers identified in CTCs are highly correlated with those of simultaneously sampled tumors, but may occasionally differ from those of primary tumors resected years before the development of metastatic disease. Certain features, such as proliferative index of CTCs (measured by Ki67 staining) differ dramatically between different clinical stages of disease. Mutations conferring acquired resistance to targeted agents can be detected within CTCs and their prevalence in the CTC population increases in concert with the advent of clinical drug resistance. Finally, RNA sequencing approaches may be used to generate digital expression profiles of CTCenriched populations, providing confirmation as to their cell of origin, as well as identifying potential transcript that are upregulated in CTCs and may contribute to their metastatic propensity. Together, the molecular analysis of CTCs offers the potential to monitor drug responses in clinical trials, and also to identify potential new therapeutic targets aimed at suppressing cancer metastasis.
Monday 9 July 2012
12:15−13:00
FEBS Lecture: Drug Development 68 Targeted Cancer Therapy Development A. Ullrich1 . 1 Max-Planck Institute for Biochemistry, Department of Molecular Biology, Martinsried, Germany For the past years we have investigated various aspects of signaling systems in tumor cells in order to identify critical switch points in the pathophysiological process that results in malignancy. These efforts aim at the selective blockade of abnormal, disease-promoting signaling mechanisms by monoclonal antibodies, or small molecule kinase inhibitors. This strategic approach began with the cloning of the EGF receptor cDNA and the related receptor HER-2/neu and translated the animal oncogene concept into target-directed personalized therapy of human cancer. This work yielded the first specific oncogene target-based, FDA-approved (1998) personalized, therapeutic agent, “Herceptin”, for the treatment of metastatic breast cancer of a subgroup of individually defined patients. Earlier and subsequent “targetdriven drug development” efforts that employed various genomic analysis strategies led to the cancer therapies that are based on EGFR, HER3, FGFR4, Axl/Ufo and Flk-1/VEGFR2 as critical signaling elements in tumor progression. The latter served, in cooperation with SUGEN Inc./Pharmacia/Pfizer, as basis for the development of SU11248/Sunitinib. The drug discovery process that started with Herceptin and led to Sunitinib represents a prototypical example for the adaptation of cancer therapeutics from highly specific to multi-targeted drugs. While all novel cancer therapies target genetic alterations in tumor tissues innovative strategies are aimed at investigating the contribution of germ line determinants of the patient to disease progression and therapy response. One example is the common polymorphism at codon position 388 in the human FGFR4 gene of which the Arg388 allele represents a target for the development of individual genotype-dependent cancer therapy development. Current findings and their consequences for patient-specific cancer therapy will be presented.
Monday 9 July 2012
14:30−15:15
Ramon Areces Foundation Lecture: Non Coding RNA
67 Molecular Characterization of Circulating Tumour Cells D. Haber1 . 1 Massachusetts General Hospital Cancer Center, MGH Cancer Center, Boston MA, USA Circulating tumor cells (CTCs) are shed into the bloodstream from primary epithelial cancers and their metastatic deposits. Although extraordinarily rare among normal blood components, they provide a unique opportunity to noninvasively sample tumor cells, monitor their response to therapy and potentially predict the emergence of drug resistance. Nowhere is this more critical than in the new field of targeted cancer therapies, where continuous analysis of tumor genotypes may allow rational adjustments of treatment
69 The ceRNA Hypothesis and the Non-coding Revolution in Cancer Research and Therapy P. Pandolfi1 . 1 Beth Israel Deaconess Cancer Center and Harvard Medical School, Boston, MA, USA The central dogma of molecular biology, as proposed by Francis Crick, demonstrates that genetic information is transferred from DNA in our genomes to the generation of functional proteins, through a messenger RNA (mRNA) intermediate. This suggests that the key function of each mRNA is to encode for protein.