Ian Edward David Smith

Bio: Ian Edward David Smith is an academic researcher from GlaxoSmithKline. The author has contributed to research in topics: Ubiquitin ligase & Bicyclic molecule. The author has an hindex of 17, co-authored 37 publications receiving 1547 citations. Previous affiliations of Ian Edward David Smith include University of Cambridge & University of Hertfordshire.

Catalytic in vivo protein knockdown by small-molecule PROTACs

Abstract: The current predominant therapeutic paradigm is based on maximizing drug-receptor occupancy to achieve clinical benefit This strategy, however, generally requires excessive drug concentrations to ensure sufficient occupancy, often leading to adverse side effects Here, we describe major improvements to the proteolysis targeting chimeras (PROTACs) method, a chemical knockdown strategy in which a heterobifunctional molecule recruits a specific protein target to an E3 ubiquitin ligase, resulting in the target's ubiquitination and degradation These compounds behave catalytically in their ability to induce the ubiquitination of super-stoichiometric quantities of proteins, providing efficacy that is not limited by equilibrium occupancy We present two PROTACs that are capable of specifically reducing protein levels by >90% at nanomolar concentrations In addition, mouse studies indicate that they provide broad tissue distribution and knockdown of the targeted protein in tumor xenografts Together, these data demonstrate a protein knockdown system combining many of the favorable properties of small-molecule agents with the potent protein knockdown of RNAi and CRISPR

HaloPROTACS: Use of Small Molecule PROTACs to Induce Degradation of HaloTag Fusion Proteins

Abstract: Small molecule-induced protein degradation is an attractive strategy for the development of chemical probes. One method for inducing targeted protein degradation involves the use of PROTACs, heterobifunctional molecules that can recruit specific E3 ligases to a desired protein of interest. PROTACs have been successfully used to degrade numerous proteins in cells, but the peptidic E3 ligase ligands used in previous PROTACs have hindered their development into more mature chemical probes or therapeutics. We report the design of a novel class of PROTACs that incorporate small molecule VHL ligands to successfully degrade HaloTag7 fusion proteins. These HaloPROTACs will inspire the development of future PROTACs with more drug-like properties. Additionally, these HaloPROTACs are useful chemical genetic tools, due to their ability to chemically knock down widely used HaloTag7 fusion proteins in a general fashion.

PROTAC-Mediated Degradation of Bruton's Tyrosine Kinase Is Inhibited by Covalent Binding.

Abstract: The impact of covalent binding on PROTAC-mediated degradation of BTK was investigated through the preparation of both covalent binding and reversible binding PROTACs derived from the covalent BTK inhibitor ibrutinib. It was determined that a covalent binding PROTAC inhibited BTK degradation despite evidence of target engagement, while BTK degradation was observed with a reversible binding PROTAC. These observations were consistently found when PROTACs that were able to recruit either IAP or cereblon E3 ligases were employed. Proteomics analysis determined that the use of a covalently bound PROTAC did not result in the degradation of covalently bound targets, while degradation was observed for some reversibly bound targets. This observation highlights the importance of catalysis for successful PROTAC-mediated degradation and highlights a potential caveat for the use of covalent target binders in PROTAC design.

Extended pharmacodynamic responses observed upon PROTAC-mediated degradation of RIPK2.

Abstract: Proteolysis-Targeting Chimeras (PROTACs) are heterobifunctional small-molecules that can promote the rapid and selective proteasome-mediated degradation of intracellular proteins through the recruitment of E3 ligase complexes to non-native protein substrates. The catalytic mechanism of action of PROTACs represents an exciting new modality in drug discovery that offers several potential advantages over traditional small-molecule inhibitors, including the potential to deliver pharmacodynamic (PD) efficacy which extends beyond the detectable pharmacokinetic (PK) presence of the PROTAC, driven by the synthesis rate of the protein. Herein we report the identification and development of PROTACs that selectively degrade Receptor-Interacting Serine/Threonine Protein Kinase 2 (RIPK2) and demonstrate in vivo degradation of endogenous RIPK2 in rats at low doses and extended PD that persists in the absence of detectable compound. This disconnect between PK and PD, when coupled with low nanomolar potency, offers the potential for low human doses and infrequent dosing regimens with PROTAC medicines.

Compounds&methods for the enhanced degradation of targeted proteins&other polypeptides by an e3 ubiquitin ligase

Abstract: The present invention relates to bifunctional compounds, which find utility as modulators of targeted ubiquitination, especially inhibitors of a variety of polypeptides and other proteins which are degraded and/or otherwise inhibited by bifunctional compounds according to the present invention. In particular, the present invention is directed to compounds, which contain on one end a VHL ligand which binds to the ubiquitin ligase and on the other end a moiety which binds a target protein such that the target protein is placed in proximity to the ubiquitin ligase to effect degradation (and inhibition) of that protein. The present invention exhibits a broad range of pharmacological activities associated with compounds according to the present invention, consistent with the degradation/inhibition of targeted polypeptides.

Modern Organic Synthesis with α-Diazocarbonyl Compounds

Abstract: Alan Ford,† Hugues Miel, Aoife Ring,† Catherine N. Slattery,† Anita R. Maguire,*,†,‡ and M. Anthony McKervey* †Department of Chemistry and ‡School of Pharmacy, Analytical and Biological Chemistry Research Facility, Synthesis and Solid State Pharmaceutical Centre, University College Cork, Cork, Ireland Almac Discovery Ltd., David Keir Building, Stranmillis Road, Belfast BT9 5AG, United Kingdom Almac Sciences Ltd., Almac House, 20 Seagoe Industrial Estate, Craigavon BT63 5QD, United Kingdom

Induced protein degradation: an emerging drug discovery paradigm

Abstract: Small-molecule drug discovery has traditionally focused on occupancy of a binding site that directly affects protein function, and this approach typically precludes targeting proteins that lack such amenable sites. Furthermore, high systemic drug exposures may be needed to maintain sufficient target inhibition in vivo, increasing the risk of undesirable off-target effects. Induced protein degradation is an alternative approach that is event-driven: upon drug binding, the target protein is tagged for elimination. Emerging technologies based on proteolysis-targeting chimaeras (PROTACs) that exploit cellular quality control machinery to selectively degrade target proteins are attracting considerable attention in the pharmaceutical industry owing to the advantages they could offer over traditional small-molecule strategies. These advantages include the potential to reduce systemic drug exposure, the ability to counteract increased target protein expression that often accompanies inhibition of protein function and the potential ability to target proteins that are not currently therapeutically tractable, such as transcription factors, scaffolding and regulatory proteins.

Catalytic in vivo protein knockdown by small-molecule PROTACs

Abstract: The current predominant therapeutic paradigm is based on maximizing drug-receptor occupancy to achieve clinical benefit This strategy, however, generally requires excessive drug concentrations to ensure sufficient occupancy, often leading to adverse side effects Here, we describe major improvements to the proteolysis targeting chimeras (PROTACs) method, a chemical knockdown strategy in which a heterobifunctional molecule recruits a specific protein target to an E3 ubiquitin ligase, resulting in the target's ubiquitination and degradation These compounds behave catalytically in their ability to induce the ubiquitination of super-stoichiometric quantities of proteins, providing efficacy that is not limited by equilibrium occupancy We present two PROTACs that are capable of specifically reducing protein levels by >90% at nanomolar concentrations In addition, mouse studies indicate that they provide broad tissue distribution and knockdown of the targeted protein in tumor xenografts Together, these data demonstrate a protein knockdown system combining many of the favorable properties of small-molecule agents with the potent protein knockdown of RNAi and CRISPR

Structural basis of PROTAC cooperative recognition for selective protein degradation.

Abstract: Inducing macromolecular interactions with small molecules to activate cellular signaling is a challenging goal. PROTACs (proteolysis-targeting chimeras) are bifunctional molecules that recruit a target protein in proximity to an E3 ubiquitin ligase to trigger protein degradation. Structural elucidation of the key ternary ligase-PROTAC-target species and its impact on target degradation selectivity remain elusive. We solved the crystal structure of Brd4 degrader MZ1 in complex with human VHL and the Brd4 bromodomain (Brd4BD2). The ligand folds into itself to allow formation of specific intermolecular interactions in the ternary complex. Isothermal titration calorimetry studies, supported by surface mutagenesis and proximity assays, are consistent with pronounced cooperative formation of ternary complexes with Brd4BD2. Structure-based-designed compound AT1 exhibits highly selective depletion of Brd4 in cells. Our results elucidate how PROTAC-induced de novo contacts dictate preferential recruitment of a target protein into a stable and cooperative complex with an E3 ligase for selective degradation.