Lari Lehtiö - Discovery of chemical probes for human mono ADP-ribosyltransferases
Human mono ADP-ribosyltransferases (mARTDs) of the PARP/ARTD family regulate biological activities through ADP-ribosylation of target proteins. They only transfer a single ADP-ribose unit to the target residue in contrast to e.g. founding member of the family, DNA damage response enzyme PARP1/ARTD1. Until very recently there were no selective inhibitors available for any of the mARTDs and I will describe our efforts to discover first inhibitors for ARTD10, an enzyme involved in cell death, NF-kB signaling and S-phase DNA repair. The chemical probe rescues the cells from ARTD10 induced apoptosis and sensitizes the cells to the hydroxyurea-induced genotoxic stress. The chemical scaffold, OUL35, and its new binding mode to the active site open up a path towards discovery of chemical tools to study also other mARTDs of the family.
Guillaume Médard - Chemoproteomics-aided drug discovery
In this presentation, EPHA2 will be used as a prototypical example of a therapeutically interesting protein kinase, with no dedicated inhibitor, for which chemical proteomics has been instrumental along the discovery pipeline. It will be shown how chemical proteomics has been used to establish the therapeutic relevance of this target (target selection and validation), how we used another flavour of this approach to establish its inhibition landscape (screening), how it helped us design a medicinal chemistry campaign (lead selection), and how we used it to assess the affinity and selectivity of each synthetized inhibitor candidate during the medicinal chemistry efforts (lead optimization).
Katrine Qvortrup - Design and Synthesis of New Linkers for Antibody-Drug Conjugates
Antibody Drug Conjugates (ADCs) are monoclonal antibodies attached to biologically active drugs by chemical linkers with labile bonds. ADCs hold considerable promise as anticancer agents, offering the potential of specific delivery of cytotoxic agents to tumour cells (targeted therapy),[1,2] thereby avoiding the dose-limiting toxicity of chemotherapy that occurs as a result of its effects on normal cells. Background: ADCs are comprised of three parts: a monoclonal antibody, a cytotoxic agent (the ‘warhead’) and a structural moiety that joins the two together (the ‘linker’), Figure A. The antibody of the ADC is selected or engineered to bind to a tumour cell-specific antigen or to an antigen that is over-expressed on the surface of tumour cells. Thus, the antibody guides the ADC selectively to target tumour cells. Upon binding, the ADC is internalised and the cytotoxic agent is released from the antibody to perform its cell-killing function.[2-5] Recent years have witnessed tremendous interest in ADCs; two are already on the market as anticancer agents (Roche’s Kadcyla and Seattle Genetics’ Adcetris) and there are now a further 33 ADCs in clinical trials.[7] The development of new linkers by synthetic chemists will be crucial to the further advancement of the field and the emergence of next generation ADCs. Aim: We now wish to report the design and development of novel linker technologies for ADC chemotherapeutics. Indeed, linker technology is known to profoundly impact upon ADC potency, specificity and safety.[3,7] The knowledge and insights gained can potentially be applied to other synergistic therapeutic modalities. The research is conducted in collaboration with Professor David Spring, Cambridge University. All new ADCs produced are continuously being evaluated as chemotherapeutics in collaboration with GlaxoSmithKline. Methodology: There are two key aspects of ‘linker technology’: (1) the chemical method of attachment of the linker to the antibody and warhead and (2) the nature (and thus properties) of the linker (Figure A). We have worked to further develop both aspects of linker technology by conducting the following activities: (1) Design and synthesise new linkers and evaluate with a range of agents to make new conjugates. (2) Develop novel site-specific attachment strategies. Linker composition: There are two general classes of linkers: cleavable and non-cleavable. Cleavable linkers rely on processes that occur within the cell to liberate the warhead.[9] Non-cleavable linkers require catabolic degradation of the antibody; this results in release of the warhead still bound to the linker, which in turn is bonded to the amino acid through which it was attached to the antibody.[2,3,6,9] In the current project, we have examined a variety of bioorthogonal warhead de-attachment strategies. Specifically, we have developed novel light and enzymatically cleavage strategies, allowing for the mild release of bioactive compounds (examples are presented in Figure B). Site-specific conjugation: Conjugation of the linker to the antibody is generally achieved by reaction with functional groups of naturally occurring lysine and cysteine amino acids in the antibody (Figure B).[2] There is an inherent lack of sophistication with the ‘traditional’ attachment approach in that it is pseudorandom: in theory, any of the targeted amino acids within the antibody can be modified.[9] Consequently, the ADCs generated using this approach will be heterogeneous in terms of the number of drug molecules incorporated and their locations on the antibody.[9] Recent years have witnessed considerable interest in developing linker technologies that are ‘site-specific’; that is, where sites of attachment of the linker (and thus the warhead) to the antibody are defined. Site-specific conjugation is expected to yield more consistent ADCs, with improved stability, efficacy and safety.[2,5,6,8] In the current project, we examine the application of two bioorthogonal methodologies[10] to the synthesis of site-specific ADCs. Specifically, we have developed novel site-specific conjugation strategies, where reactivity depends on the synergistic interaction of two or more naturally occurring amino acids. (Figure B). References: [1] Nicolaou, K. Angew. Chem. Int. Ed. 2014, 53, 9128. [2] Ducry, L.; Stump, B. Bioconjugate Chem. 2010, 21, 5. [3] Chari, R. V. J. et al. Angew. Chem. Int. Ed. 2014, 53, 3796. [4] Ducry, L.; Stump, B. Bioconjugate Chem. 2010, 21, 5. [5] Flygare, J. A. et al. Chem. Biol. Drug. Des. 2013, 81, 113. [6] Kitson, S. L. et al., Chimica Oggi-Chemistry Today, July/August 2013, 31. [7] Thayer, A. M. Chemical & Engineering News 2014, 92, 13. [8] Challenger, C. BioPharma International 2014, 27, 22. [9] Ritter, A., Pharmaceutical Technology 2012, 42. [10] Sletten, E. M.; Bertozzi, C. R. Angew. Chem. Int. Ed. 2009, 48, 6974.
Kristian Strømgaard - Targeting Protein-Protein Interactions
Protein-protein interactions (PPIs) are essential to vital cellular processes, and serve as potential targets for therapeutic intervention. We are particularly interested in the PPIs between integral membrane proteins and their intracellular protein partners. We have developed peptide-based inhibitors of the PSD-95/glutamate receptor interaction, by exploiting that PSD-95 contains a tandem PDZ1-2 domain. So we designed and synthesized dimeric peptides with low nanomolar affinities,1 and have demonstrated that these ligands are potential treatment for ischemic stroke.2 For the same PPI, we examined the importance of backbone hydrogen bond by employing amide-to-ester mutations in peptide ligands3 and proteins.4 Finally, we have exploited the principle of dimeric peptide-based ligands to perturb the PPI between the scaffolding protein gephyrin and glycine/GABAA receptors.5,6 Most recently we have developed high affinity, cell-permeable peptides and demonstrated how these can modulate receptors and used to label synapses.7
