Evaluating the thrombin generation profiles of four different r FV FV III products in FV FV III‐deficient plasma using FIX FIX a and FXI FXI a activation

摘要

Introduction The thrombin generation assay ( TGA ) can be used to monitor factor replacement therapy in patients with haemophilia. The TGA assay is typically performed using tissue factor as the reaction activator; however, activating with FIX a or FXI a can enhance assay sensitivity when FVIII ??1%. Aims To evaluate the sensitivity of the TGA when FIX a (5?nmol/L) and FXI a (0.22?nmol/L) are used to activate the assay in platelet‐poor plasma and to compare these data to the one‐stage and chromogenic assays. Methods Plasma from 10 severe FVIII ‐deficient subjects was supplemented with FVIII (0%, 0.1%, 0.4%, 1.2%, 4%, 11% and 33%), using either Novo Eight ? , Advate ? , Eloctate ? , turoctocog alfa pegol or a control standard. The one‐stage and chromogenic assays quantified the FVIII levels. The TGA assay was activated using either FIX a or FXI a. Results Both FIX a‐ and FXI a‐activated TGA were sensitive across FVIII concentrations, with intra‐assay coefficient of variation ( CV )??10%. The FXI a‐activated assay had 25% CV at the lowest level of FVIII compared to 10% CV with FIX a activation. There were strong correlations between the FIX a‐ and FXI a‐activated TGA tests ( R 2 ?=?0.9912) and between the one‐stage and chromogenic assays ( R 2 ?=?0.9469). However, there were poor relationships between the TGA tests and one‐stage and chromogenic assays. Conclusions Both FIX a‐ and FXI a activation results in similar TGA profiles across a FVIII range of 0.1%‐33%; however, FIX a activation was more robust at the lowest levels of FVIII compared with FXI a activation.