Activity-based probes in bioimaging
We were the first to report on small, irreversible uPA inhibitors with nanomolar potency and a surprising selectivity against highly related enzymes such as tPA, plasmin, thrombin and fXa. Selected inhibitors showed very promising results in a rat metastasis model of breast cancer.20 We further elaborated our UPA inhibitors into highly potent uPA activity-based chemical probes. These probes showed promising bioimaging (fluorescence, PET, SPECT) results in the field of oncology.33, 34
33. Ides, J.; Thomae, D.; Wyffels, L.; Vangestel, C.; Messagie, J.; Joossens, J.; Lardon, F.; Van der Veken, P.; Augustyns, K.; Stroobants, S.; Staelens, S. Synthesis and in vivo preclinical evaluation of an F-18 labeled uPA inhibitor as a potential PET imaging agent. Nucl. Med. Biol. 2014, 41, 477-487.34. Vangestel, C.; Thomae, D.; Van Soom, J.; Ides, J.; Wyffels, L.; Pauwels, P.; Stroobants, S.; Van der Veken, P.; Magdolen, V.; Joossens, J.; Augustyns, K.; Staelens, S. Preclinical evaluation of In-111 MICA-401, an activity-based probe for SPECT imaging of in vivo uPA activity. Contrast Media Mol. Imaging 2016, 11, 448-458.
Bioorthogonal chemistry in bioimaging
Currently we are developing F-18 labeled TCO analogues that are stable under in vivo conditions to allow a two-step derivatisation of tetrazine-labeled antibodies for imaging studies.35, 36
35. Wyffels, L.; Thomae, D.; Waldron, A. M.; Fissers, J.; Dedeurvvaerdere, S.; Van der Veken, P.; Joossens, J.; Stroobants, S.; Augustyns, K.; Staelens, S. In vivo evaluation of F-18-labeled TCO for pre-targeted PET imaging in the brain. Nucl. Med. Biol. 2014, 41, 513-523.36. Maggi, A.; Ruivo, E.; Fissers, J.; Vangestel, C.; Chatterjee, S.; Joossens, J.; Sobott, F.; Staelens, S.; Stroobants, S.; Van der Veken, P.; Wyffels, L.; Augustyns, K. Development of a novel antibody-tetrazine conjugate for bioorthogonal pretargeting. Org. Biomol. Chem. 2016, 14, 7544-7551.
Modified substrate assisted screening (MSAS) and on-target synthesis
Significant effort was put in optimizing the Substrate Activity Screening (SAS) methodology, an approach published by Ellman for identifying fragment-sized building blocks for enzyme inhibitors. This resulted in our “Modified SAS” (MSAS) technology, the power of which was demonstrated by the identification of novel inhibitor building blocks for urokinase, Atg4B and caspase 1. In addition, novel strategies to derivatize the fragments into finalized small molecule inhibitors, were elaborated.37, 38 Currently, several of these strategies are being investigated in so-called “on-target” conditions. Here, the biochemical target functions as a physical template that selects fragments with optimal affinity. Emphasis is put on the evaluation of reaction types that hitherto have not been reported for “on-target” fragment assembly.
37. Gladysz, R.; Adriaenssens, Y.; De Winter, H.; Joossens, J.; Lambeir, A. M.; Augustyns, K.; Van der Veken, P. Discovery and SAR of Novel and Selective Inhibitors of Urokinase Plasminogen Activator (uPA) with an Imidazo 1,2-a pyridine Scaffold. J. Med. Chem. 2015, 58, 9238-9257.38. Gladysz, R.; Cleenewerck, M.; Joossens, J.; Lambeir, A. M.; Augustyns, K.; Van der Veken, P. Repositioning the Substrate Activity Screening (SAS) Approach as a Fragment-Based Method for Identification of Weak Binders. ChemBioChem 2014, 15, 2238-2247.
We developed a new virtual screening metric to be used in the field of cheminformatics, and invented the spectrophore technology to be used as a powerful virtual screening descriptor.39
39. Lopes, J. C. D.; Dos Santos, F. M.; Martins, J. C.; Augustyns, K.; De Winter, H. The power metric: a new statistically robust enrichment-type metric for virtual screening applications with early recovery capability. Journal of Cheminformatics 2017, 9, 7.