Luisella Toschi

Predictive biomarker discovery through the parallel integration of clinical trial and functional genomics datasets

The European Union multi-disciplinary Personalised RNA interference to Enhance the Delivery of Individualised Cytotoxic and Targeted therapeutics (PREDICT) consortium has recently initiated a framework to accelerate the development of predictive biomarkers of individual patient response to anti-cancer agents. The consortium focuses on the identification of reliable predictive biomarkers to approved agents with anti-angiogenic activity for which no reliable predictive biomarkers exist: sunitinib, a multi-targeted tyrosine kinase inhibitor and everolimus, a mammalian target of rapamycin (mTOR) pathway inhibitor. Through the analysis of tumor tissue derived from pre-operative renal cell carcinoma (RCC) clinical trials, the PREDICT consortium will use established and novel methods to integrate comprehensive tumor-derived genomic data with personalized tumor-derived small hairpin RNA and high-throughput small interfering RNA screens to identify and validate functionally important genomic or transcriptomic predictive biomarkers of individual drug response in patients. PREDICTs approach to predictive biomarker discovery differs from conventional associative learning approaches, which can be susceptible to the detection of chance associations that lead to overestimation of true clinical accuracy. These methods will identify molecular pathways important for survival and growth of RCC cells and particular targets suitable for therapeutic development. Importantly, our results may enable individualized treatment of RCC, reducing ineffective therapy in drug-resistant disease, leading to improved quality of life and higher cost efficiency, which in turn should broaden patient access to beneficial therapeutics, thereby enhancing clinical outcome and cancer survival. The consortium will also establish and consolidate a European network providing the technological and clinical platform for large-scale functional genomic biomarker discovery. Here we review our current understanding of molecular mechanisms driving resistance to anti-angiogenesis agents, the current limitations of laboratory and clinical trial strategies and how the PREDICT consortium will endeavor to identify a new generation of predictive biomarkers.

Abstract 4460: Targeting the redox-protective protein MTH1 for cancer therapy: A novel way to exploit the unique redox status of cancer cells

Cancer cells are characterized by an increase in the rate of reactive oxygen species (ROS) production and an altered redox environment compared to normal cells. The role of ROS in tumorigenesis is two-fold. On the one hand, ROS play a causal role in tumor development and progression by inducing genomic instability and aberrant, pro-tumorigenic signalling. On the other hand, high levels of ROS can also be toxic to cancer cells, oxidizing and damaging both DNA and free nucleotides (dNTPs), which can lead to cell death. MutT Homolog 1 (MTH1) is a redox-protective phosphatase that converts ROS-oxidized nucleotides (8-oxo-dGTP) into their corresponding monophosphates, thus preventing their incorporation into genomic DNA and the resultant DNA damage and cell death. Recent studies have shown that MTH1 is up-regulated in various cancers and its activity is required for cancer cell survival and proliferation. Genetic knockdown of MTH1 and MTH1 small molecule inhibition led to DNA damage and cancer-specific cell death in vitro and in vivo, while having little effect on normal cells with a lower rate of ROS production. Hence, the unique redox status of cancer cells makes them reliant on redox-protective proteins like MTH1, which opens a novel therapeutic window to selectively induce cancer cell death via oxidative stress, while sparing normal cells. In order to validate MTH1 as a potential cancer therapeutic target, a wide range of cancer cells (lung, bone, colon, skin, and breast) were treated with a selective MTH1 inhibitor (TH588) or MTH1 shRNAs, and analysed for proliferation, cell survival, ROS levels and DNA damage. We found that MTH1 inhibition impaired cancer cell proliferation as well as anchorage-independent growth. Furthermore, TH588 induced cancer cell damage, as assessed by DNA damage markers and cancer cell death. Various normal, non-transformed cells (normal bronchial epithelial cells, normal lung fibroblasts and normal human epidermal melanocytes) were not affected by MTH1 inhibition. Antioxidants, which eliminate ROS, reversed the effects on cancer cells, indicating that ROS is the driver of cancer cell death and growth impairment upon MTH1 inhibition. Consequently, combination approaches using the MTH1 inhibitor together with pro-oxidants, further increased cancer cell susceptibility to oxidative stress. Based on our data, a MTH1 inhibitor may have clinical potential as a single agent or in combination with ROS inducers for the treatment of patients with various forms of cancer. Citation Format: Andrea Glasauer, Horst Irlbacher, Anja Richter, Luisella Toschi, Michael Steckel, Andrea Haegebarth. Targeting the redox-protective protein MTH1 for cancer therapy: A novel way to exploit the unique redox status of cancer cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4460. doi:10.1158/1538-7445.AM2015-4460

Abstract 4746: Pharmacological characterization of BAY-876, a novel highly selective inhibitor of glucose transporter (GLUT)-1 in vitro and in vivo

One hallmark of cancer is the accelerated metabolism, high energy requirements, and increased glucose uptake by the tumor cells, the latter being the first and rate-limiting step for glucose metabolism. Glucose transport into the tumor cell is mediated by facilitative high-affinity glucose transporter (GLUT) proteins. Among the 14 GLUT proteins, expression of GLUT1 in normal organs is nearly exclusively restricted to the blood brain barrier, while other GLUTs are also expressed in a wide variety of vital organs such as liver and heart. Interestingly, GLUT1 expression is highly regulated by hypoxia-inducible factor (HIF)-1α, a key driver of tumor progression. In line with this finding, GLUT1 over-expression was found to be associated with tumor progression and poor overall survival in various tumor indications. Consequently, GLUT1 represents a potential target for cancer treatment. Therefore, we have developed a highly-selective GLUT1 inhibitor, namely BAY-876, with selectivity over GLUT2, 3, and 4 of 4700-, 800-, and 135-fold, respectively. We here show for the first time the pharmacological characterization of BAY-876, comprising inhibition of glucose-uptake, anti-proliferative activity in vitro, and anti-tumor efficacy in vivo in models of different tumor indications in monotherapy as well as first results on the combinability of BAY-876. Furthermore, at the therapeutic dose, BAY-876 treatment did not show any relevant finding on the behavior of treated mice in the Irwin test, assuming no or only minor effects on brain function. In conclusion, BAY-876 is the first GLUT1-selective inhibitor which reduces glucose uptake and growth of tumor cells with sufficient tolerability at the efficacious dose in preclinical models. Citation Format: Charlotte Kopitz, Luisella Toschi, Carolyn Algire, Melanie Heroult, Anna-Lena Frisk, Kirstin Meyer, Arndt Schmitz, Eleni Lagkadinou, Heike Petrul, Iring Heisler, Roland Neuhaus, Bernd Buchmann, Herbert Himmel, Marcus Bauser, Andrea Haegebarth, Karl Ziegelbauer. Pharmacological characterization of BAY-876, a novel highly selective inhibitor of glucose transporter (GLUT)-1 in vitro and in vivo. [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 4746.