Coagulation factor X (activated factor X variant) (FXa variant)

Coagulation factor X / activated factor X – DOAC-insensitive recombinant analog refers to a class of engineered serine proteases designed to restore blood clotting in patients treated with direct oral anticoagulants (DOACs). Unlike decoy receptors like Andexanet alfa, which bind and sequester the inhibitor, these analogs are catalytically active variants of factor Xa that have been modified to be resistant to inhibition by drugs such as apixaban and rivaroxaban. The most prominent example is the FXa-I16L variant, which remains functional in the presence of these inhibitors by altering the binding pocket or the activation transition state. In a clinical context, these molecules serve as 'bypass agents' to treat life-threatening bleeding or to allow for emergency surgery in anticoagulated patients. By maintaining their ability to convert prothrombin to thrombin despite the presence of DOACs, they provide a direct mechanism to achieve hemostasis. Research into these analogs also extends to gene therapy applications for hemophilia, where a DOAC-resistant factor could provide stable coagulation even if the patient requires temporary anticoagulation for other conditions. Their development represents a shift from sequestration-based reversal strategies to functional restoration of the coagulation cascade.

Other names

DOAC-resistant factor XaDOAC-insensitive factor XaCatalytically active recombinant factor Xa variantFXa-I16LFactor Xa variant

These recombinant analogs are engineered to maintain catalytic procoagulant activity while possessing structural modifications (such as the I16L mutation) that prevent direct oral anticoagulants (DOACs) from binding to and inhibiting the enzyme. By bypassing the inhibitory effect of DOACs, these variants can restore thrombin generation and promote hemostasis in the presence of therapeutic or supratherapeutic levels of factor Xa inhibitors.