Design of Polyphosphate Inhibitors that Reduce Thrombosis without Increased Bleeding

C.C. La^1,2, S.A. Smith³, M.D.G. Jaraquemada-Peláez^1,2, S. Abbina^1,4, L.A. Creagh⁵, C.A. Haynes⁵, J.H. Morrissey³, J.N. Kizhakkedathu^1,2,4

¹University of British Columbia, Centre for Blood Research, Vancouver, Canada, ²University of British Columbia, Department of Chemistry, Vancouver, Canada, ³University of Michigan, Department of Biological Chemistry, Ann Arbor, United States, ⁴University of British Columbia, Department of Pathology and Laboratory Medicine, Vancouver, Canada, ⁵University of British Columbia, Department of Chemical and Biological Engineering, Vancouver, Canada

Abstract Number: PB0259

Meeting: ISTH 2020 Congress

Theme: Coagulation and Natural Anticoagulants » Contact Pathway

Background: Polyphosphate (polyP) has been shown to be a potent procoagulant polyanion. We present a strategic design of inhibitors with high specificity to polyP and minimized non-specific interactions. A switchable protonation state has been utilized, whereby the inhibitors present a low charge state in solution prior to polyP binding but increase its cationic charge upon binding to polyP thereby increasing its potency.

Aims: Design a polyP inhibitor that exhibits a tailored affinity for polyP and minimized non-specific interactions with blood components to prevent adverse effects on bleeding.

Methods: Inhibitors were synthesized using a systematic increase of varied cationic moieties (ligands) to generate a library of compounds on a polymer scaffold. The library was characterized by their charge content in solution by conductometry and potentiometry. The binding events between polyP and inhibitors was studied by isothermal calorimetry (ITC). The activity of inhibitors were assessed using plasma clotting activity.

Results: A library of synthesized compounds ranging from 10 kDa to 23 kDa were functionalized with a range of 10 – 30 ligands. Protonatibility of inhibitors confirmed both strongly cationic (pKa > 8) and switchable protonation states (pKa 6.5 – 7.5) were successfully incorporated. Upon binding to polyP, inhibitors were able to recruit protons from its surroundings to satisfy the charge requirement to inhibit polyP as determined by ITC. Plasma clotting assays confirmed the activities of these new generation polyP inhibitors.

Conclusions: We present the strategic design of potent polyP inhibitors that were antithrombotic without the potential of increased bleeding. We confirm the successful utilization of a switchable protonation state to increase specificity and reduce non-specific interactions of our new generation polyP inhibitors.

To cite this abstract in AMA style:

La CC, Smith SA, Jaraquemada-Peláez MDG, Abbina S, Creagh LA, Haynes CA, Morrissey JH, Kizhakkedathu JN. Design of Polyphosphate Inhibitors that Reduce Thrombosis without Increased Bleeding [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/design-of-polyphosphate-inhibitors-that-reduce-thrombosis-without-increased-bleeding/. Accessed October 1, 2023.

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