OC 17.4 - Effects of andexanet alfa on different thrombin generation and anti-Xa-methods in vitro.

Sunday, July 10, 2022

11:30 AM – 11:45 AM

Location: ExCel Center, ICC Capital Suite Room 10&11

Presentation Format: In-Person

Presenting Author(s)

Yvonne Henskens, MSc PhD

Professor in Clinical Chemistry, Clinical chemist
Central Diagnostic Laboratory at Maastricht University Medical Centre+
Maastricht, Limburg, Netherlands

Co-Author(s)

AG

Anouk Gulpen

Internal medicine/pHD
Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
Maastricht, Limburg, Netherlands
MB

Maaike Bruurs

Biomedical student
Central Diagnostic Laboratory, Maastricht University Medical Centre +
Maastricht, Limburg, Netherlands
Rv

René van Oerle

Chief Operating Officer
Coagulation Profile, Maastricht, The Netherlands
Maastricht, Limburg, Netherlands
KW

Kristien Winckers

MD
Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University
Maastricht, Limburg, Netherlands
RO

Renske Olie

MD, vascular medicine
Departments of Biochemistry nd vascular medicine, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands;
Maastricht, Limburg, Netherlands
At

Arina J. ten Cate-Hoek

Associate Professor, MD
Thrombosis Expertise Center, Heart & Vascular Center, Maastricht University Medical Center, Maastricht, the Netherlands
Maastricht, Limburg, Netherlands
HS

Henri M.H. Spronk

Chief Executive Officer
Coagulation Profile, Maastricht, the Netherlands
Maastricht, Limburg, Netherlands
Hugo ten Cate, MD, PhD, FAHA

Professor, MD, PhD
Thrombosis Expertise Center, Heart & Vascular Center, Maastricht University Medical Center, Maastricht, the Netherlands
Maastricht, Limburg, Netherlands

Background: Andexanet alfa is a recombinant human factor Xa, used to treat life threatening bleedings caused by oral aXa inhibitors. It has been suggested that andexanet interacts with TFPI and could increase the risk for thrombosis. Conventional anti-Xa-tests to measure the andexanet effect are not yet applicable due to plasma sample dilutions, causing dissociation of andexanet from the Xa-inhibitor. Thrombin generation (TG) assays could offer more clinical relevant information on the andexanet effect.

Aims: The effects of direct Xa inhibitors, andexanet alfa and TFPI were studied in vitro using two different thrombin generation assays and a traditonal or a modified aXa assay.

Methods: Various concentrations of rivaroxaban/apixaban with or without andexanet/anti-TFPI were added to normal pool or individual plasma’s. TG was measured using several reagents by manual calibrated automated thrombogram (CAT)-1 method (Thrombinoscope) or automated ST Genesia . AXa levels were determined using a commercial (Hyphen) or modified aXa protocol.

Results: An andexanet concentration of 25 μg/mL and 100 μg/mL restored TG in samples containing rivaroxaban/apixaban concentrations of respectively 0-200 ng/mL and >500 ng/ml. An overshoot of baseline TG levels was noticed after adding andexanet, which was reversed by a TFPI-antibody. Small differences were found between the CAT-1 and ST Genesia measurement. The commercial anti-FXa test still showed high DOAC levels after the addition of andexanet, which did not correlate with TG levels. The modified test resulted in more expected levels of Xa-inhibitors but a complete inhibition by andexanet was not seen.

Conclusion(s): The addition of andexanet alfa to normal plasma samples spiked with rivaroxaban or apixaban reversed the effects of the DOACs in both thrombin generation assays resulting in more thrombin generation compared to baseline. The influence of TFPI in the increase in thrombin generation after andexanet-alfa was proven by using anti-TFPI. Traditional and modified aXa assays are not suitable for andexanet monitoring.