# Modulating Fibrinolysis Dynamics by Leveraging Multivalent Avidity to Control Enzyme Activity

> **NIH NIH R01** · INDIANA UNIVERSITY INDIANAPOLIS · 2024 · $463,113

## Abstract

PROJECT SUMMARY
Blood clots kill more humans than any other single pathogenic cause. A new or recurrent diagnosis of venous
thromboembolism (VTE), which encompasses both pulmonary embolism (PE) and deep vein thrombosis
(DVT), affects >900,000 people each year in the US alone. Current PE standard of care includes the delivery
of acute clot digesting enzymes such as recombinant tissue Plasminogen Activator (tPA), administered IV or
by catheter. All currently FDA cleared clot digesting enzymes rely on activation of the patient’s endogenous
plasminogen converting nearly all of it to active clot digesting plasmin. This widespread activation massively
depletes plasmin regulatory proteins, causing unchecked digestion of both pathogenic and beneficial blood
clots resulting in a 5-10% rate of major bleeding complications, including intracranial hemorrhage. Due to
safety concerns and contraindications nearly 50% of patients that would benefit from active clot digesting
interventions are not eligible to receive the current therapy. Direct infusion of exogenous active plasmin to
digest blood clots is limited due to the nearly instantaneous inactivation by circulating α2-antiplasmin (serpin
protein) and α2-macroglobulin (steric inhibitor). To address the current limitations of plasmin infusion as a
direct fibrinolytic therapeutic intervention, a novel clot digesting delivery strategy leveraging multivalent
enzymatic control is necessary. Preliminary data demonstrates that reversible competitive inhibitors can be
used to deliver active plasmin with reduced inactivation from regulatory proteins in-vitro while still allowing
efficient clot digestion; however, there is critical need to determine the underlying characteristics responsible
for protection and delivery of plasmin as a direct fibrinolytic in-vivo. This proposal will identify critical
relationships that contribute to multivalent control of active enzymes in-vivo for the novel clinical translation
of therapeutic interventions to digest blood clots with an improved safety profile. Aim 1: Determine how homo-
and hetero-multivalent inhibitors impact inhibition of plasmin and its interactions with regulatory proteins in-
vitro; Aim 2: Evaluate the impact of reversible multivalent enzyme inhibition on clot digestion efficiency of
standardized ex-vivo blood clots under shear; and, Aim 3: Examine the impact of multivalent inhibitor
delivered plasmin on clot targeting and digestion in-vivo. Overall, these experiments will identify key
multivalent enzyme delivery principles and provide lead compounds to be further developed. A safer direct
fibrinolytic therapeutic will have expanded indications for use that include: ischemic stroke, myocardial
infarction, limb ischemia, PE, DVT, and occluded vascular catheters.

## Key facts

- **NIH application ID:** 10881877
- **Project number:** 5R01HL167877-02
- **Recipient organization:** INDIANA UNIVERSITY INDIANAPOLIS
- **Principal Investigator:** Nathan J Alves
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $463,113
- **Award type:** 5
- **Project period:** 2023-07-15 → 2028-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10881877

## Citation

> US National Institutes of Health, RePORTER application 10881877, Modulating Fibrinolysis Dynamics by Leveraging Multivalent Avidity to Control Enzyme Activity (5R01HL167877-02). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10881877. Licensed CC0.

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