Engineering and evaluation of FXa bypassing agents that restore hemostasis following Apixaban associated bleeding

Area of Science:

• Biochemistry
• Pharmacology
• Computational Biology

Background:

• Direct oral anticoagulants (DOACs) targeting Factor Xa (FXa) are crucial for preventing and treating thromboembolic disorders.
• While effective, FXa-targeting DOACs (FXaDOACs) carry a risk of anticoagulant-associated bleeding.
• Current reversal agents, like andexanet alfa, have limitations including complex dosing and thrombotic risks.

Purpose of the Study:

• To computationally design and engineer novel FXa variants with anticoagulation reversal activity.
• To evaluate these engineered FXa variants as potential safer alternatives for reversing FXaDOACs.
• To assess the efficacy and safety profile of designed FXa variants in preclinical models.

Main Methods:

• Utilized computational design and protein engineering to create FXa variants.
• Assessed the binding affinity of DOACs to engineered FXa variants.
• Evaluated the enzymatic activity and hemostasis-restoring capacity of FXa variants in mouse models treated with apixaban.

Main Results:

• Designed FXa variants demonstrated low binding affinity for FXaDOACs.
• Engineered variants retained FXa enzymatic activity.
• These FXa variants effectively reduced apixaban-associated bleeding in mice by restoring hemostasis.
• Unlike andexanet alfa, designed agents did not inhibit TFPI, suggesting a potentially improved thrombogenic profile.

Conclusions:

• Novel FXa variants were successfully designed and engineered for FXaDOAC reversal.
• These variants show promise as effective and potentially safer agents for managing FXaDOAC-associated bleeding.
• The designed FXa variants may offer an improved safety profile compared to existing reversal therapies due to their mechanism of action.