Factor VIII Activity and Factor VIII Inhibitors Can Be Measured Accurately in Plasma Containing Mim8 by Using...

Area of Science:

• Hematology
• Clinical Diagnostics
• Pharmacology

Background:

• Patients with Haemophilia A treated with Mim8 may require Factor VIII (FVIII) replacement therapy.
• Accurate assessment of FVIII activity (FVIII:C) and FVIII inhibitors is essential for managing these patients.

Purpose of the Study:

• To evaluate the accuracy of different chromogenic substrate assays (CSAs) for monitoring FVIII:C and FVIII inhibitors in the presence of Mim8.
• To identify reliable CSAs for clinical use in patients receiving Mim8 treatment.

Main Methods:

• Five CSAs with varying Factor IX and X sources (bovine, bovine-human, human) were tested.
• FVIII:C and FVIII inhibitor levels were measured in plasma spiked with Mim8 at different concentrations.
• Assays were assessed for interference and accuracy in measuring standard half-life (SHL) and extended half-life (EHL) FVIII products.

Main Results:

• Human CSAs showed significant interference with Mim8.
• Bovine CSAs accurately measured FVIII:C for SHL and EHL FVIII products without interference.
• Bovine-human CSAs exhibited interference at lower FVIII concentrations, increasing with Mim8 levels.
• Bovine CSAs accurately measured FVIII inhibitor levels in the presence of Mim8.

Conclusions:

• Bovine CSAs are reliable for monitoring FVIII:C and FVIII inhibitor levels in Mim8-treated patients across all FVIII concentrations.
• Bovine-human CSAs can be used for FVIII:C monitoring when FVIII concentrations exceed 20 IU/dL.
• These findings support the use of specific CSAs for precise patient management.