• 5T4 as a target for immunotherapy in renal cell carcinoma.

      Elkord, Eyad; Shablak, Alaaeldin; Stern, Peter L; Hawkins, Robert E (2009-12)
    • Antivascular agents for non-small-cell lung cancer: current status and future directions.

      Amir, Eitan; Mandoky, Laszlo; Blackhall, Fiona H; Thatcher, Nick; Klepetko, Walter; Ankersmit, Hendrik Jan; Reza Hoda, Mir Ali; Ostoros, Gyula; Dank, Magdolna; Dome, Balazs; et al. (2009-11)
      BACKGROUND: Despite improvements in surgery and chemo(radio)therapy which have allowed for modest advances in the treatment of patients with non-small-cell lung cancer (NSCLC), survival remains poor and further improvements are needed. Attention over recent years has focused, therefore, on targeted therapies, with notable success in the development of antivascular drugs. OBJECTIVE: To summarize the current knowledge on antivascular therapy in patients with NSCLC. METHOD: Review of randomized controlled trials exploring treatment of NSCLC patients with antivascular drugs. RESULTS/CONCLUSION: Bevacizumab, a humanized monoclonal antibody against the vascular endothelial growth factor (VEGF), when added to cytotoxic chemotherapy, was the first treatment to prolong the overall survival of patients with advanced NSCLC beyond 12 months, a significant breakthrough in the management of advanced NSCLC. Small-molecule tyrosine kinase inhibitors and alternative antivascular strategies such as VEGF-trap and vascular disrupting agents are also being investigated and have shown promise in clinical trials. This review summarizes the most recent and important findings in antivascular agents in NSCLC.
    • Biomarker method validation in anticancer drug development.

      Cummings, Jeffrey; Ward, Timothy H; Greystoke, Alastair; Ranson, Malcolm R; Dive, Caroline; Clinical and Experimental Pharmacology, Paterson Institute for Cancer Research, University of Manchester, Manchester, UK. jcummings@picr.man.ac.uk (2008-02)
      Over recent years the role of biomarkers in anticancer drug development has expanded across a spectrum of applications ranging from research tool during early discovery to surrogate endpoint in the clinic. However, in Europe when biomarker measurements are performed on samples collected from subjects entered into clinical trials of new investigational agents, laboratories conducting these analyses become subject to the Clinical Trials Regulations. While these regulations are not specific in their requirements of research laboratories, quality assurance and in particular assay validation are essential. This review, therefore, focuses on a discussion of current thinking in biomarker assay validation. Five categories define the majority of biomarker assays from 'absolute quantitation' to 'categorical'. Validation must therefore take account of both the position of the biomarker in the spectrum towards clinical end point and the level of quantitation inherent in the methodology. Biomarker assay validation should be performed ideally in stages on 'a fit for purpose' basis avoiding unnecessarily dogmatic adherence to rigid guidelines but with careful monitoring of progress at the end of each stage. These principles are illustrated with two specific examples: (a) absolute quantitation of protein biomarkers by mass spectrometry and (b) the M30 and M65 ELISA assays as surrogate end points of cell death.
    • Caveolin-1 and mitochondrial SOD2 (MnSOD) function as tumor suppressors in the stromal microenvironment: a new genetically tractable model for human cancer associated fibroblasts.

      Trimmer, C; Sotgia, F; Whitaker-Menezes, D; Balliet, Renee M; Eaton, Gregory; Martinez-Outschoorn, Ubaldo E; Pavlides, Stephanos; Howell, Anthony; Iozzo, Renato V; Pestell, Richard G; et al. (2011-02-15)
      We have recently proposed a new model for understanding tumor metabolism, termed: "The Autophagic Tumor Stroma Model of Cancer Metabolism". In this new paradigm, catabolism (autophagy) in the tumor stroma fuels the anabolic growth of aggressive cancer cells. Mechanistically, tumor cells induce autophagy in adjacent cancer-associated fibroblasts via the loss of caveolin-1 (Cav-1), which is sufficient to promote oxidative stress in stromal fibroblasts. To further test this hypothesis, here we created human Cav-1 deficient immortalized fibroblasts using a targeted sh-RNA knock-down approach. Relative to control fibroblasts, Cav-1 deficient fibroblasts dramatically promoted tumor growth in xenograft assays employing an aggressive human breast cancer cell line, namely MDA-MB-231 cells. Co-injection of Cav-1 deficient fibroblasts, with MDA-MB-231 cells, increased both tumor mass and tumor volume by ~4-fold. Immuno-staining with CD31 indicated that this paracrine tumor promoting effect was clearly independent of angiogenesis. Mechanistically, proteomic analysis of these human Cav-1 deficient fibroblasts identified > 40 protein biomarkers that were upregulated, most of which were associated with i) myofibroblast differentiation, or ii) oxidative stress/hypoxia. In direct support of these findings, the tumor promoting effects of Cav-1 deficient fibroblasts could be functionally suppressed (nearly 2-fold) by the recombinant over-expression of SOD2 (superoxide dismutase 2), a known mitochondrial enzyme that de-activates superoxide, thereby reducing mitochondrial oxidative stress. In contrast, cytoplasmic soluble SOD1 had no effect, further highlighting a specific role for mitochondrial oxidative stress in this process. In summary, here we provide new evidence directly supporting a key role for a loss of stromal Cav-1 expression and oxidative stress in cancer-associated fibroblasts, in promoting tumor growth, which is consistent with "The Autophagic Tumor Stroma Model of Cancer". The human Cav-1 deficient fibroblasts that we have generated are a new genetically tractable model system for identifying other suppressors of the cancer-associated fibroblast phenotype, via a genetic "complementation" approach. This has important implications for understanding the pathogenesis of triple negative and basal breasts cancers, as well as tamoxifen-resistance in ER+ breast cancers, which are all associated with a Cav-1 deficient "lethal" tumor micro-environment, driving poor clinical outcome.
    • Cytokine production and inflammation drive autophagy in the tumor microenvironment: role of stromal caveolin-1 as a key regulator.

      Martinez-Outschoorn, U E; Whitaker-Menezes, D; Lin, Z; Flomenberg, N; Howell, Anthony; Pestell, R G; Lisanti, M P; Sotgia, F; Thomas Jefferson University, Philadelphia, PA, USA. (2011-06-01)
      Recently, we proposed a new paradigm for understanding the role of the tumor microenvironment in breast cancer onset and progression. In this model, cancer cells induce oxidative stress in adjacent fibroblasts. This, in turn, results in the onset of stromal autophagy, which produces recycled nutrients to "feed" anabolic cancer cells. However, it remains unknown how autophagy in the tumor microenvironment relates to inflammation, another key driver of tumorigenesis. To address this issue, here we employed a well-characterized co-culture system in which cancer cells induce autophagy in adjacent fibroblasts via oxidative stress and NFκB-activation. We show, using this co-culture system, that the same experimental conditions that result in an autophagic microenvironment, also drive in the production of numerous inflammatory mediators (including IL-6, IL-8, IL-10, MIP1a, IFNg, RANTES (CCL5) and GMCSF). Furthermore, we demonstrate that most of these inflammatory mediators are individually sufficient to directly induce the onset of autophagy in fibroblasts. To further validate the in vivo relevance of these findings, we assessed the inflammatory status of Cav-1 (-/-) null mammary fat pads, which are a model of a bonafide autophagic microenvironment. Notably, we show that Cav-1 (-/-) mammary fat pads undergo infiltration with numerous inflammatory cell types, including lymphocytes, T-cells, macrophages and mast cells. Taken together, our results suggest that cytokine production and inflammation are key drivers of autophagy in the tumor microenvironment. These results may explain why a loss of stromal Cav-1 is a powerful predictor of poor clinical outcome in breast cancer patients, as it is a marker of both (1) autophagy and (2) inflammation in the tumor microenvironment. Lastly, hypoxia in fibroblasts was not sufficient to induce the full-blown inflammatory response that we observed during the co-culture of fibroblasts with cancer cells, indicating that key reciprocal interactions between cancer cells and fibroblasts may be required.
    • How can we improve our understanding of cardiovascular safety liabilities to develop safer medicines?

      Laverty, H G; Benson, C; Cartwright, E J; Cross, M J; Garland, C; Hammond, T; Holloway, C; McMahon, N; Milligan, J; Park, B K; et al. (2011-06)
      Given that cardiovascular safety liabilities remain a major cause of drug attrition during preclinical and clinical development, adverse drug reactions, and post-approval withdrawal of medicines, the Medical Research Council Centre for Drug Safety Science hosted a workshop to discuss current challenges in determining, understanding and addressing 'Cardiovascular Toxicity of Medicines'. This article summarizes the key discussions from the workshop that aimed to address three major questions: (i) what are the key cardiovascular safety liabilities in drug discovery, drug development and clinical practice? (ii) how good are preclinical and clinical strategies for detecting cardiovascular liabilities? and (iii) do we have a mechanistic understanding of these liabilities? It was concluded that in order to understand, address and ultimately reduce cardiovascular safety liabilities of new therapeutic agents there is an urgent need to: • Fully characterize the incidence, prevalence and impact of drug-induced cardiovascular issues at all stages of the drug development process. • Ascertain the predictive value of existing non-clinical models and assays towards the clinical outcome. • Understand the mechanistic basis of cardiovascular liabilities; by addressing areas where it is currently not possible to predict clinical outcome based on preclinical safety data. • Provide scientists in all disciplines with additional skills to enable them to better integrate preclinical and clinical data and to better understand the biological and clinical significance of observed changes. • Develop more appropriate, highly relevant and predictive tools and assays to identify and wherever feasible to eliminate cardiovascular safety liabilities from molecules and wherever appropriate to develop clinically relevant and reliable safety biomarkers.
    • Hypoxic human cancer cells are sensitized to BH-3 mimetic–induced apoptosis via downregulation of the Bcl-2 protein Mcl-1.

      Harrison, Luke R; Micha, Dimitra; Brandenburg, Martin; Simpson, Kathryn L; Morrow, Christopher J; Denneny, Olive; Hodgkinson, Cassandra L; Yunus, Zaira; Dempsey, Clare E; Roberts, Darren L; et al. (2011-03-01)
      Solid tumors contain hypoxic regions in which cancer cells are often resistant to chemotherapy-induced apoptotic cell death. Therapeutic strategies that specifically target hypoxic cells and promote apoptosis are particularly appealing, as few normal tissues experience hypoxia. We have found that the compound ABT-737, a Bcl-2 homology domain 3 (BH-3) mimetic, promotes apoptotic cell death in human colorectal carcinoma and small cell lung cancer cell lines exposed to hypoxia. This hypoxic induction of apoptosis was mediated through downregulation of myeloid cell leukemia sequence 1 (Mcl-1), a Bcl-2 family protein that serves as a biomarker for ABT-737 resistance. Downregulation of Mcl-1 in hypoxia was independent of hypoxia-inducible factor 1 (HIF-1) activity and was consistent with decreased global protein translation. In addition, ABT-737 induced apoptosis deep within tumor spheroids, consistent with an optimal hypoxic oxygen tension being necessary to promote ABT-737–induced cell death. Tumor xenografts in ABT-737–treated mice also displayed significantly more apoptotic cells within hypoxic regions relative to normoxic regions. Synergies between ABT-737 and other cytotoxic drugs were maintained in hypoxia, suggesting that this drug may be useful in combination with chemotherapeutic agents. Taken together, these findings suggest that Mcl-1–sparing BH-3 mimetics may induce apoptosis in hypoxic tumor cells that are resistant to other chemotherapeutic agents and may have a role in combinatorial chemotherapeutic regimens for treatment of solid tumors.
    • Optimisation of circulating biomarkers of cell death for routine clinical use.

      Greystoke, Alastair; Cummings, Jeffrey; Ward, Timothy H; Simpson, Kathryn L; Renehan, Andrew G; Butt, Fouziah; Moore, David; Gietema, J; Blackhall, Fiona H; Ranson, Malcolm R; et al. (2008-05)
      BACKGROUND: M30 and M65 enzyme-linked immunosorbent assays detect circulating cytokeratin 18 fragments released during caspase-dependent or total cell death, respectively, and have potential as biomarkers in epithelial cancers. While these assays have been validated, their robustness for routine clinical use is unknown. PATIENTS AND METHODS: M30 and M65 were measured in matched serum and plasma samples from 31 lung cancer patients and 18 controls. RESULTS: Time allowable between sample acquisition and processing is critical for assays in clinical use. A 4-h delay in processing at room temperature increased M30 (P < 0.0001), an effect minimised by incubation on ice. M30 and M65 in serum were resistant to processing variations including delays. Serum and plasma measurements correlated well although M30 but not M65 was lower in serum (P < 0.0005). Less variation between duplicate assays was observed in serum. Prolonged storage (-80 degrees C) led to increased M30 (12%, 6 months; 34%, 1 year). Sample dilution in the supplied assay diluent proved non-linear, whereas dilution in donor serum or porcine plasma restored linearity up to a ratio of 1 : 6. CONCLUSION: We present recommendations that improve the reliability of these assays for clinical use and recommend serum as the preferred matrix with data more resistant to variations in collection.
    • Overcoming endocrine resistance in breast cancer: are signal transduction inhibitors the answer?

      Bedard, Philippe L; Freedman, Orit C; Howell, Anthony; Clemons, Mark; Division of Medical Oncology, Princess Margaret Hospital, Toronto, ON, Canada. (2008-04)
      Endocrine therapy is probably the most important systemic therapy for hormone receptor positive breast cancer. Hormonal manipulation was the first targeted treatment employed in breast cancer therapy even before the role of the estrogen (ER) and progesterone receptors (PR) had been elucidated. Unfortunately, a substantial proportion of patients, despite being ER and/or PR positive, are either primarily resistant to hormone therapies or will develop hormone resistance during the course of their disease. Signaling through complex growth factor receptor pathways, which activate the ER are emerging as important causes of endocrine resistance. Targeted therapies, such as signal transduction inhibitors (STIs), are being explored as agents to be able to potentially overcome this crosstalk and thus, resistance to hormone treatment. This article reviews the biology of the ER, the proposed mechanisms of endocrine resistance, and ongoing clinical trials with STIs in combination with hormonal manipulation as a means to overcome endocrine resistance.
    • Regulation of breast cancer stem cell activity by signaling through the Notch4 receptor.

      Harrison, Hannah; Farnie, Gillian; Howell, Sacha J; Rock, Rebecca E; Stylianou, Spyros; Brennan, Keith; Bundred, Nigel J; Clarke, Robert B; Breast Biology Group, School of Cancer, Enabling Sciences and Technology, Paterson Institute for Cancer Research, University of Manchester, Manchester Academic Health Sciences Centre, The Christie NHS Foundation Trust; Department of Medical Oncology, The Christie NHS Foundation Trust, Manchester M20 4BX, United Kingdom. (2010-01-15)
      Notch receptor signaling pathways play an important role not only in normal breast development but also in breast cancer development and progression. We assessed the role of Notch receptors in stem cell activity in breast cancer cell lines and nine primary human tumor samples. Stem cells were enriched by selection of anoikis-resistant cells or cells expressing the membrane phenotype ESA(+)/CD44(+)/CD24(low). Using these breast cancer stem cell populations, we compared the activation status of Notch receptors with the status in luminally differentiated cells, and we evaluated the consequences of pathway inhibition in vitro and in vivo. We found that Notch4 signaling activity was 8-fold higher in stem cell-enriched cell populations compared with differentiated cells, whereas Notch1 signaling activity was 4-fold lower in the stem cell-enriched cell populations. Pharmacologic or genetic inhibition of Notch1 or Notch4 reduced stem cell activity in vitro and reduced tumor formation in vivo, but Notch4 inhibition produced a more robust effect with a complete inhibition of tumor initiation observed. Our findings suggest that Notch4-targeted therapies will be more effective than targeting Notch1 in suppressing breast cancer recurrence, as it is initiated by breast cancer stem cells.
    • Targeting blood vessels for the treatment of non-small cell lung cancer.

      Amir, Eitan; Hughes, Sarah; Blackhall, Fiona H; Thatcher, Nick; Ostoros, Gyula; Timar, Jozsef; Tovari, Jozsef; Kovacs, Gabor; Dome, Balazs; Department of Medical Oncology, Christie Hospital NHS Trust, Manchester, United Kingdom. (2008-08)
      Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related mortality worldwide. Although modest survival benefit has been observed with surgery, radiotherapy and platinum-based chemotherapy, an efficacy plateau has been reached. It has become obvious, therefore, that additional treatments are needed in order to provide an improved survival benefit for these patients. The use of molecular targeted therapies, particularly those against tumor capillaries, has the potential to improve outcomes for NSCLC patients. Bevacizumab, a recombinant humanized monoclonal antibody against vascular endothelial growth factor (VEGF), is the first targeted drug that has shown survival advantage when combined with chemotherapy in NSCLC. Other antivascular agents, including vascular disrupting agents (VDAs) and different small-molecule receptor tyrosine kinase inhibitors, have also shown promise in phase I and II trials in NSCLC. The aim of this study is to describe the clinical properties of these drugs and to discuss the evidence that supports their use in the treatment of NSCLC. Furthermore, we plan to review the main pitfalls of antivascular strategies in NSCLC cancer therapy as well as assess the future direction of these treatment methods with an emphasis on clarifying the molecular background of the effects of these drugs and defining the biomarkers.