Sept. 24, 2024 — Thrombolytic Science, LLC (TSI) has announced that the U.S. Food and Drug Administration (FDA) has cleared its Investigational New Drug (IND) application for mutant prourokinase, a recombinant fibrinolytic pro-enzyme. A U.S.-based clinical trial will further confirm the safety and tolerability of TSI's novel mutant prourokinase (mproUK) in healthy volunteers.
“We are thrilled to achieve this important milestone with the FDA clearance for our first U.S. clinical trial of mproUK,” said Alexis C. Wallace, MSc. Eng., MBA, CEO of TSI. “Our innovative approach to fibrinolytic therapy has the potential to transform the treatment landscape for life-threatening thrombotic conditions, offering patients a faster, safer, and more effective reperfusion option. Following promising Phase II results from the DUMAS trial in stroke patients in the Netherlands, we’re now advancing to a Phase II trial in the UK for myocardial infarction following MHRA approval. This IND clearance is a significant step toward expanding access to our low-dose fibrinolytic treatment for broader patient populations globally."
In the natural, physiological mechanism of clot lysis, while tissue plasminogen activator (tPA) initiates clot lysis, prourokinase completes the dissolution of the fibrin clot.
"This difference is comparable to the starter of a car and its engine. tPA is like the starter, whereas prourokinase is the engine”, explained Victor Gurewich, MD, TSI co-founder and discoverer of prourokinase. "Physiological fibrinolysis requires a mini bolus of r-tPA followed by an infusion of a low dose of mproUK. In recent clinical studies, this treatment has been shown to be free of bleeding risk and rethrombosis while having the potential to re-establish blood flow earlier and being more cost effective than in-hospital surgical solutions.”
This treatment is based on the natural, biological clot dissolving mechanism involving the sequence of tPA and prourokinase, the latter having been stabilized by a single site mutation. This mutation has significantly improved the safety of prourokinase without interfering with its biological clot lysing mechanism of action. A successful proof of concept clinical trial using native prourokinase in heart attack patients, preceded by a mini dose of tPA was previously published, the PATENT trial. More recently, promising results were obtained with mutant proUK in ischemic stroke patients, the DUMAS trial.
For more information, visit www.tsillc.net
March 20, 2026 
