Fragment-based approaches to inhibitors of urokinase plasminogen activator (uPA)

Date: 10 May 2016

Venue: UAntwerp, Campus Middelheim, Building A, A.143 - Middelheimlaan 1 - 2020 Antwerp (Wilrijk)

Time: 3:00 PM - 5:00 PM

PhD candidate: Rafaela Gladysz

Principal investigator: Koen Augustyns

Co-principal investigator: Pieter Van der Veken

Short description: Phd defence Rafaela Gladysz - Department Pharmaceutical Sciences


Fragment-based approaches to inhibitors of urokinase plasminogen activator (uPA)

Fragment-Based Drug Discovery (FBDD) has evolved into an established methodology for ‘hit’ identification. Nonetheless, the approach still faces a number of fundamental challenges.[1] One of these relates to the need for specialized cost- and time-intensive  biophysical techniques to detect and study weak binding fragments. The Substrate Activity Screening (SAS) approach has been proposed as a relatively cheap and straightforward alternative for the identification of fragments for enzyme inhibitors.[2] In spite of some promising results, it has so far only seen limited investigation mainly by the group of Jonathan Ellman.[3]

In this study, we applied SAS to the discovery of inhibitors of oncology target urokinase (uPA). During our investigation, a number of unreported limitations of the SAS-based approach were uncovered. In response, we developed a modified, more efficient alternative method: the MSAS approach.[4] MSAS not only circumvents the limitations of SAS but also broadens its scope by providing additional fragments and more coherent SAR data. As a result, we identified a number of interesting S1-binding fragments for uPA. The latter were used to prepare scaffold-based inhibitors following the Groebke-Blackburn-Bienaymé (GBB) three-component reaction protocol. Optimization of the initial hit compound provided reversible non-peptidic uPA inhibitors of nanomolar potency and high selectivity against the related trypsin-like serine proteases.[5]

Additionally, in the course of this study a number of inhibitors carrying a warhead function were prepared, and served as a proof-of-concept for the SAS-based identification of uPA inhibitors.

In the last part of this PhD research the 'on-target' approach to inhibitors of uPA has been explored, yielding a general experimental protocol as well as an early proof-of-concept for the on-target version of the GBB reaction.


  • [1]   Murray, C. W.; Verdonk, M. L.; Rees, D. C., Trends Pharmacol. Sci. 2012, 33, 224-232.
  • [2]   Wood, W. J. L.; Patterson, A. W.; Tsuruoka, H.; Jain, R. K.; Ellman, J. A., J. Am. Chem. Soc. 2005, 127, 15521-15527.
  • [3]   Gladysz, R.; Lambeir, A.-M.; Joossens, J.; Augustyns, K.; Van der Veken, P., ChemMedChem, 2016, 11, 467-476 (review article).
  • [4]   Gladysz, R.; Cleenewerck, M.; Joossens, J.; Lambeir, A.-M.; Augustyns, K.; Van der Veken, P. ChemBioChem 2014, 15, 2238-2247.
  • [5]   Gladysz, R.; Adriaenssens, Y.; De Winter, H., Joossens, J.; Lambeir, A.-M.; Augustyns, K.; Van der Veken, P., Journal of Medicinal Chemistry, 2015, 58, 9238‑9257.