PB1101 - Investigation of the reversal potential of engineered Factor Xa agents in apixaban and rivaroxaban treated plasma

Tuesday, June 25, 2024

13:45 – 14:45 ICT

Room: Exhibition Hall

Presenting Author(s)

WJ

Wojciech Jankowski

Biologist
US FDA
Silver Spring, Maryland, United States

Co-Author(s)

SS

Stepan Surov

Scientist
US FDA
Silver Spring, Maryland, United States
MO

Mikhail Ovanesov

Principal Investigator
US FDA
Silver Spring, Maryland, United States
ZS

Zuben Sauna

Division Director
US FDA
Silver Spring, Maryland, United States

Background: Direct oral anticoagulants (DOACs) targeting Factor Xa (FXa) are used in prevention and treatment of thromboembolic disorders. However, DOAC treatment carries the risk of anticoagulant-associated bleeding. The only approved reversal agent for FXa inhibitors, andexanet alfa, is a catalytically inactive truncated variant of human FXa that binds and temporarily sequesters FXa inhibitors. Using a computational guided approach, we previously reported the engineering and initial evaluation of novel FXa variants that retain enzymatic function in the presence of apixaban and reduces apixaban-associated bleeding in mice. Here we investigate the reversal potential of both FXa designs in the presence of the two most prescribed DOACs, apixaban and rivaroxaban.

Aims: Evaluate potential of two novel FXa variants to reverse the inhibitory effects of apixaban and rivaroxaban in normal pooled plasma (NPP) in vitro and benchmark the potential of the new FXa variants with current therapy.

Methods: Factor Xa variants were computationally designed to retain enzymatic function in the presence of apixaban and reduce apixaban-associated bleeding. The procoagulant activity of novel FXa variants and andexanet alfa was evaluated in thrombin generation assay in NPP using low (0.1µM) and high (2µM) doses of apixaban and rivaroxaban. The normal FXa activity range was obtained for human plasma in the absence of DOACs and FXa variants.

Results: Compared to andexanet alfa, considerably lower levels of the FXa-variants designed by us were required to restore FXa activity to physiological levels following treatment with apixaban or rivaroxaban. In the presence of high concentrations of apixaban, andexanet alfa, unlike the FXa-variants, does not reverse the DOAC-induced inhibition of FXa activity.

Conclusion(s): FXa variants designed and evaluated by us in this study can evade apixaban and rivaroxaban induced inactivation of FXa.