Abstract 4200: New potential therapeutic applications of WX-UK1, as a specific and potent inhibitor of human trypsin-like proteases

WX-UK1 (the active metabolite of upamostat) was originally developed as an inhibitor of the serine protease urokinase (uPA) with a Ki ~1 uM. To identify more sensitive targets, we performed a bioinformatic analysis of the ~200 human trypsin-like serine proteases, many of which play crucial roles in homeostasis and disease. Among these we selected a subset for biochemical analysis based on an inspection of modelled 3D structures of WX-UK1:protease complexes and sequence alignment of binding site residues. Samples of the selected proteases were prepared and characterized for their binding to WX-UK1; enzymatically with respect to inhibition constant (Ki) and by surface plasmon resonance with respect to dissociation constant (kd). We now report that WX-UK1 is a potent and specific inhibitor of five human serine proteases (trypsin-3, trypsin-2, trypsin-1 and matriptase-1 and trypsin-6), with Ki9s down to the low nanomolar range, 19 nM for trypsin-3. Several of these serine proteases are known to be associated with cancer progression and metastasis. As a compound with an established clinical safety profile, targeted use of upamostat in oncology and extension to non-oncology indications may be assessed. Citation Format: Emil Oldenburg, Christine R. Schar, Eva Lange, Terry F. Plasse, Danielle T. Abramson, Reza Fathi, Eric M. Towler, Mark Levitt, Jan K. Jensen. New potential therapeutic applications of WX-UK1, as a specific and potent inhibitor of human trypsin-like proteases [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4200.