Affinity-based design of a synthetic universal reversal agent for heparin anticoagulants

Abstract

Heparin-based anticoagulant drugs have been widely used for the prevention of blood clotting during surgical procedures and for the treatment of thromboembolic events. However, bleeding risks associated with these anticoagulants demand continuous monitoring and neutralization with suitable antidotes. Protamine, the only clinically approved antidote to heparin, has shown adverse effects and ineffectiveness against low-molecular weight heparins and fondaparinux, a heparin-related medication. Alternative approaches based on cationic molecules and recombinant proteins have several drawbacks including limited efficacy, toxicity, immunogenicity, and high cost. Thus, there is an unmet clinical need for safer, rapid, predictable, and cost-effective anticoagulant-reversal agents for all clinically used heparins. We report a design strategy for a fully synthetic dendritic polymer-based universal heparin reversal agent (UHRA) that makes use of multivalent presentation of branched cationic heparin binding groups (HBGs). Optimization of the UHRA design was aided by isothermal titration calorimetry studies, biocompatibility evaluation, and heparin neutralization analysis. By controlling the scaffold's molecular weight, the nature of the protective shell, and the presentation of HBGs on the polymer scaffold, we arrived at lead UHRA molecules that completely neutralized the activity of all clinically used heparins. The optimized UHRA molecules demonstrated superior efficacy and safety profiles and mitigated heparin-induced bleeding in animal models. This new polymer therapeutic may benefit patients undergoing high-risk surgical procedures and has potential for the treatment of anticoagulant-related bleeding problems.

Nontoxic polyphosphate inhibitors reduce thrombosis while sparing hemostasis

“…16 Conversely, laser-induced thrombosis in mouse cremaster arterioles has been shown to be sensitive to intervention at more clinically relevant levels of antithrombotic therapy. 12,17 In previous toxicity studies 10 as well as those reported here (supplemental Figure 4), UHRAs did not show hemolysis and red blood cell aggregation even at 5 mg/mL, whereas protamine and PEI induced significant hemolysis. UHRA compounds also did not show any effect on thrombin generation in human PRP; furthermore, UHRAs were well tolerated in mice after intravenous injection with no adverse effects up to 200 mg/kg (the maximum injected dose) in vivo, and the maximum tolerated dose was not reached.…”

“…UHRA compounds also did not show any effect on thrombin generation in human PRP; furthermore, UHRAs were well tolerated in mice after intravenous injection with no adverse effects up to 200 mg/kg (the maximum injected dose) in vivo, and the maximum tolerated dose was not reached. 10 Conversely, protamine was tolerated up to only 20 mg/kg. Biodistribution studies using tritiated UHRA (23 kDa) gave a plasma half-life of about 40 minutes with very low accumulation in vital organs (about 8% of the initial dose in the liver and 2% in spleen, kidney, heart, and lung after 48 hours) and was cleared mainly via the kidneys.…”

“…10 These UHRAs were designed by assembling multifunctional cationic groups into the core of a dendritic polymer; they are then shielded from nonspecific interactions with blood components by using a protective layer of short-chain polyethylene glycol (PEG), resulting in increased biocompatibility compared with conventional cationic polymers.…”

Małopłytkowość indukowana protaminą — nowy problem czy inny typ małopłytkowości poheparynowej?

“…Najbardziej obiecującymi następcami protaminy wydają się UHRA (universal heparin reversal agents) -będący w fazie badań przedklinicznych oraz andeksanet alfa i aripazine (PER977) -obecnie testowane na pacjentach. Andeksanet alfa -rekombinowane biał-ko i aripazyna -małocząsteczkowy, kationowy związek, hamują aktywność bezpośrednich inhibitorów czynnika Xa, dając szanse na odwrócenie działania heparyn [37,40]. W wyniku syntezy i licznych modyfikacji chemicznych na przełomie kilku ostatnich lat również grupa autorów niniejszego artykułu opracowała szereg polimerów, z któ-rych na podstawie wstępnych badań wyselekcjonowano najbardziej obiecujące zamienniki protaminy.…”

Cysteine proteases of human hookwormNecator Americanus as virulencefactors and implications for drug design with anti-heparin and heparin analogs: A bioinformatics study

“…Anti-heparin agents had been previously designed to prevent excessive bleeding caused by clinically used heparin. [64] . The molecular content of worm heparin, if and when characterized, could enable the design of appropriate positively charged anti-heparin molecules.…”