Project

new oral targeted anticancer agents; tyrosine kinase inhibitors; cellular resistance; cancer stem cells; therapeutic drug monitoring; Philadelphia-positive leukemia ; cellular pharmacoproteomics

Lead
Lay summary
A number of new oral anticancer agents were recently or are still being developed, such as tyrosine kinase inhibitors (TKIs) and other small molecules able to interfere with specific cell signal transduction mechanisms. They are about to revolutionize cancer treatment, and to transform deadly malignancies into chronically manageable conditions. Nevertheless, primary or secondary drug resistance, persistence of cancer stem cells and drug adverse effects still limit these long-term treatments in their ability to stabilize or even cure malignant diseases. Poor tolerance and therapeutic failure are not uncommon, and relapse is a nearly inevitable consequence of treatment interruption. Moreover, TKIs are characterized by important interindividual pharmacokinetic (PK) and pharmacodynamic (PD) variability, that warrants the clinical development of monitoring methods aimed to standardize drug exposure. Up to now, most investigations on the PK/PD aspects of TKIs therapy have focused on TKI concentration in plasma. However, TKIs act intracellularly, and their concentrations in cell cytoplasm, besides being determined by circulating blood levels, are also controlled by various transmembrane drug transporters influencing cellular uptake and release. Moreover, TKIs pharmacological activity in cells is modulated by complex mutual biological, genetic and environmental influences, which remain poorly known.  This research project aims at increasing our understanding of the complex gene-proteome-environnement interplay that influences the efficacy and toxicity of new targeted anticancer TKIs at the cellular level, using Philadelphia-positive leukemia as paradigm. We propose to integrate cellular pharmacokinetics (monitoring of cellular drug transport and modulation thereof), cellular pharmacodynamics (monitoring of cell responsiveness to TKI cellular exposure) and cellular pharmacoproteomics (identification of molecular mechanisms responsible for TKI resistance, especially in cancer stem cells). Our goal is to respond to clinically relevant issues from a therapeutic standpoint. The appropriate management of oncologic patients certainly requires the monitoring of these novel treatments. Beyond resting upon plasma concentration measurements, such monitoring might definitively be improved by our better understanding of TKI intracellular disposition and effects.

Direct link to Lay Summary

Last update: 21.02.2013

Natural persons

Communication	Title	Media	Place	Year

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The development of orally active tyrosine kinase inhibitors (TKIs), rationally designed to target the chimerical BCR-ABL tyrosine kinase oncoprotein of Philadelphia-positive (Ph+) leukemia is one of the greatest advances of the last decade in the field of cancer therapy. Nevertheless, despite the impressive therapeutic benefit of TKIs, the currently available molecules suppress -but do not eliminate the disease- owing to the persistence of minimal residual leukemia, such that relapse is a nearly inevitable consequence of therapy interruption. Moreover, TKIs appear to be characterized by an important interindividual pharmacokinetic and pharmacodynamic variability, with a substantial number of patients developing resistance or intolerance to treatment. Up to now, most investigations on the pharmacokinetic/pharmacodynamic aspects of TKIs therapy and of its therapeutic drug monitoring (TDM) have focused on concentration of the parent TKI drug in plasma. It is considered at present as the best pharmacokinetic marker of anticancer drug exposure and, in case of lower or higher levels, of insufficient clinical response, or toxicity, respectively. However, TKIs act intracellularly and concentrations in cell cytoplasm, although determined by circulating blood levels are also dependent of various transmembrane influx and efflux drug transporters that do modulate intracellular exposure, whereas TKIs pharmacological activity in cells is also modulated by complex mutual biological, genetic and environmental influences, remaining largely unknown. Moreover, pharmacological experiments addressing the issues of susceptibility of Ph+ leukemia cells to TKIs have so far only partly addressed the presence of important confounding factors such as cytokines’ influence and cell maturation stage.The present research proposal therefore aims at increasing the current understanding of the complex gene-proteome-environment interplay influencing the efficacy and toxicity of targeted anticancer treatments, at the cellular level, using Ph+ leukemia as paradigm. Specifically, we intend to study:1)the cellular pharmacokinetics (cellular drug transport and modulation thereof) using sensitive mass spectrometry tool, making it possible to monitor drugs’ actual exposure within cell, more closely reflecting the intracellular environment of the therapeutic target BCR-ABL;2)the impact of cell maturational stage as well as environmental influences (co-administered drugs and cytokines) on TKI pharmacodynamic responses on cell proliferation, growth inhibition and apoptose;3)the concomitant monitoring of TKI pharmacodynamics by comprehensive targeted pharmaco-proteomic arrays of activated/inhibited signaling transduction pathways in sensitive and resistant cells exposed -or not- to TKIs, using a new ultra-high sensitivity (down to one cell equivalent per spot) reverse phase protein-array platform.The overall project aims at becoming able to respond to clinically relevant issues from a therapeutic standpoint such as the actual importance of cellular drug transport to TKI activity, especially for the yet unexplored new third generation TKIs. The possibility to modulate this transport, the functional impact of TKI transport at various stages of target cells' maturation and the identification of alternate key intracellular signaling pathways possibly implicated in the resistance to TKIs will also be thoroughly explored. Integration of these latter aspects in a coordinated approach is of particular importance for the development of curative strategies for chronic myelogenous leukemia (CML), since it requires notably the identification of crucial pharmacokinetic/pharmacodynamic mechanisms responsible for the resistance of CML stem cells to TKIs. Indeed, the new targeted drugs are about to revolutionize numerous cancer treatments, but oncologic patients certainly deserve further optimization of the monitoring of these novel treatments. Such optimization can definitively be achieved by a more in-depth comprehension of TKI cellular disposition and effect.