Biomarkers for 12-lipoxygenase inhibition as a therapeutic intervention for heparin-induced thrombocytopenia and thrombosis (HIT/T)

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The goal of this project is to develop highly sensitive and reproducible biomarkers for assessment of VLX-1005 treatment of heparin-induced thrombocytopenia and thrombosis (HIT/T). VLX-1005, a 12-LOX inhibitor that potently inhibits immune-mediated thrombosis including HIT/T, has the potential to treat HIT/T in patients. HIT/T is an acquired life-threatening thrombocytopenic and thrombotic complications that occur in patients exposed to unfractionated heparin (UFH) or low molecular weight heparin (LMWH): the most widely used anticoagulants in the world. Approximately 12 million patients are exposed to UFH and LMWH annually in the US alone with ~24,000 developing HIT/T every year. HIT/T often results in aberrant platelet activation and aggregation leading to a) platelet-derived microparticle release, b) increased thrombin generation leading to catastrophic arterial and venous thrombosis that results in venous limb gangrene, c) deep venous thrombosis, and d) pulmonary embolism and death. Current treatment of HIT/T is limited to argatroban (a direct thrombin inhibitor). Unfortunately, this carries a significant risk of severe bleeding limited its effectiveness. Recent evidence has established that the enzyme 12- lipoxygenase (12-LOX), and its metabolic product, 12- hydroxyeicosatetraenoic acid (12-HETE) are key contributors to the underlying pathology of HIT/T including promoting platelet reactivity, thrombus formation/stability as well as vessel occlusion. VLX-1005 selectively and potently inhibits 12-LOX, halts aberrant platelet activation and thrombosis and has shown efficacy in numerous animal models, including mesenteric arteriole injury and laser-induced cremaster arteriole thrombosis. While the development of VLX-1005 for treatment of HIT/T is rapidly progressing, it will be important to have highly sensitive biomarkers for assessment of VLX-1005 as it intervenes and prevents morbidity and mortality often observed with the disease. To this end, we propose 2 Aims to address this concern for clinical trial readiness. In Aim 1, several biomarkers for coagulation state and platelet activation will be assessed including the thrombin-antithrombin (TAT) ELISA assay, 12-HETE assay, light transmission aggregometry (LTA), and whole blood impedance aggregometry (WBIA) in mouse models of HIT/T. These biomarkers will serve as an indicator of VLX-1005 effects on both coagulation and platelet activation. As VLX-1005 has not been shown to effect coagulation or fibrin formation, we do not expect VLX-1005 to alter coagulation conditions in the patient, however since a decreased platelet activation environment may result in decreased thrombin activation, these biomarker will inform if VLX-1005 is altering upstream coagulation. Aim 2 will take the biomarker optimization from Aim 1 and apply it to human blood samples ex vivo to determine the efficacy of the biomarkers to report VLX-1005 effects in the blood. The biomarker assay profile is essential for the planned clinical trials with VLX- 1005 for treatment of patients with HIT/T.
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