Modified Factor Xa Polypeptides for Apixaban Bleeding Reversal
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Solution Overview
Problem
Current direct oral anticoagulants (DOACs) that inhibit Factor Xa are associated with significant bleeding complications, and the available reversal agent, Andexxa®, poses risks and has limited efficacy, necessitating a safer and more effective reversal strategy.
Innovation Solution
Development of modified Factor Xa polypeptides with specific amino acid substitutions in subsites S1 and S4, which exhibit low affinity for apixaban and maintain enzymatic activity, allowing for effective reversal of DOAC-induced bleeding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Andexxa® is used as a reversal agent for FXa inhibitors, then binding and sequestration of FXa inhibitors is achieved, but risks of arterial and venous thrombosis, myocardial infarction, ischemic stroke, cardiac arrest, and sudden death increase
Solution Approach 1:
The patent applies local quality by introducing specific amino acid substitutions (W439A, G450A, G440A, C415A, C443A) at targeted locations in the Factor Xa binding pocket, particularly in subsites S1 and S4. These localized modifications alter the binding characteristics to reduce affinity for DOACs while preserving procoagulant activity, thereby achieving reversal efficacy without the harmful thrombotic effects associated with Andexxa®
Solution Approach 2:
The patent employs parameter changes by modifying the biochemical properties of Factor Xa through amino acid substitutions. These changes alter the binding affinity parameters for DOACs (reducing them significantly) while maintaining or enhancing enzymatic activity toward physiological substrates, thus achieving a safer reversal profile with reduced thrombotic risk compared to Andexxa®
2Reliability
If high dose Andexxa® is administered to reverse FXa inhibition, then bleeding reversal is achieved, but frequency and severity of thrombotic adverse events increase
Solution Approach 1:
The patent applies inversion by creating a Factor Xa variant with reversed binding characteristics compared to wild-type Factor Xa. Instead of high affinity for DOACs like the natural protein, the W439A/G450A/G440A/C415A/C443A mutant has low affinity for DOACs while maintaining high procoagulant activity, effectively inverting the normal binding profile to achieve reversal without harmful effects
3Reliability
If modified Factor Xa polypeptides with amino acid substitutions are designed, then affinity for apixaban is reduced by at least 50-fold, but structural modifications are required
Solution Approach 1:
The patent applies parameter changes by systematically modifying specific amino acid parameters (W439A, G450A, G440A, C415A, C443A) in the Factor Xa sequence to achieve at least 50-fold reduction in apixaban affinity. These targeted parameter changes in the binding pocket subsites S1 and S4 achieve the desired low DOAC affinity while maintaining structural integrity and enzymatic function
Data Source
AI summary
Modified Factor Xa polypeptides having functional activity and reduced affinity for apixaban are provided. Nucleic acids encoding the modified Factor Xa polypeptides and vectors and host cells including the nucleic acids are also provided. Methods of reducing or inhibiting bleeding, such as in a subject being treated with a direct oral anticoagulant are provided.