Abstract Number: PB0217
Meeting: ISTH 2022 Congress
Background: Mim8 is a new bispecific antibody that mimics the cofactor function of activated factor VIII (FVIIIa) by bridging activated factor IX and factor X, enhancing the activation of Factor X. Mim8, which is currently in clinical trials , is aimed for prophylactic treatment of haemophilia A patients, with or without inhibitors. Like emicizumab, it has been observed, that these new drugs can impact the results of clotting assays.
Aims: Evaluate Mim8 effects on routine coagulation assays (PT and aPTT), on one-stage and chromogenic intrinsic pathway coagulation factor assays and on thrombophilia coagulation tests using Stago reagents.
Methods: A Factor VIII deficient plasma (Stago, Asnières/Seine, France) was spiked with 1.7, 5 and 50 µg/mL of Mim8. All samples were tested once, in triplicate, in a single experiment with Stago reagents on STA-R Max analyzer.
Results: aPTT clotting times using different aPTT reagents were significantly shortened with Mim8 at all concentrations tested . Accordingly, the activity measurements of the clotting factors VIII, IX, XI and XII with a one-stage clotting assay were also significantly affected by the presence of Mim8.
It was also observed that Mim8 interferes slightly on FVIII measurement with a chromogenic assay (TriniCHROM VIII:C) (Table 1).
Mim8 has a limited impact on PT measurement and no impact on the chromogenic measurement of protein C (PC) activity and on immunoturbidimetric measurement of free protein S (PS). In contrast, PC and PS activities measured with clotting assays are significantly affected by Mim8 (Table 2).
Conclusion(s): As it has been described for emicizumab, Mim8 interferes with aPTT and aPTT based one-stage factor VIII, IX, XI and XII assays. Mim8 has a limited effect on PT measurement. Regarding PC and PS measurement, chromogenic and immunoturbidimetric assays remain unaffected by Mim8 while PC and PS levels decrease artefactually with clotting-based assays.
To cite this abstract in AMA style:Fauconnier L, Roland N, Carlo A, Hervé T, Depasse F, Ezban M, Nicoud L, Martineau N. Impacts of Mim8 on routine coagulation assays, on intrinsic pathway coagulation factor assays and on thrombophilia coagulation tests [abstract]. https://abstracts.isth.org/abstract/impacts-of-mim8-on-routine-coagulation-assays-on-intrinsic-pathway-coagulation-factor-assays-and-on-thrombophilia-coagulation-tests/. Accessed November 30, 2023.
« Back to ISTH 2022 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/impacts-of-mim8-on-routine-coagulation-assays-on-intrinsic-pathway-coagulation-factor-assays-and-on-thrombophilia-coagulation-tests/