PB0180 - Laboratory evaluation of extendend-half-life recombinant FVIII products (EHL-FVIIIs): one stage coagulation assay or chromogenic assay?

Sunday, July 10, 2022

6:30 PM – 7:30 PM

Location: Exhibition

Presentation Format: In-Person

Presenting Author(s)

RD

Raimondo De Cristofaro, MD, PhD

Professor, Haemostasis and Thrombosis Center Director
1.Fondazione Policlinico Universitario A. Gemelli, IRCCS, Center for Hemorrhagic and Thrombotic Diseases and Haemophilia Center, Rome, Italy; 2. Catholic University, Translational Medicine and Surgery Department Rome, Italy
Roma, Lazio, Italy

Co-Author(s)

Stefano Lancellotti, PhD

Biologist Health Manager
Fondazione Policlinico Universitario A. Gemelli, IRCCS, Center for Hemorrhagic and Thrombotic Diseases and Haemophilia Center, Rome, Italy
Roma, Lazio, Italy
MS

Monica Sacco

Post-doc
Catholic University, Translational Medicine and Surgery Department Rome, Italy
Roma, Lazio, Italy
Maira Tardugno, Dr

PhD Student
Catholic University, Translational Medicine and Surgery Department Rome, Italy
Roma, Lazio, Italy

Background: The EHL-FVIIIs have been introduced to improve the FVIII pharmacokinetic profile reducing the infusions number in hemophilic patients. These products are structurally and functionally heterogeneous, leading to several discrepancies in FVIII coagulant (FVIII:C) by chromogenic substrate assay (CSA) and one-stage clotting assay (OSA), and inducing an altered FVIII recovery with an over/under-estimating by more than 30%. Similar discrepancies were observed in patients receiving ReFacto® (B-domain-deleted FVIII) a decade ago and has been resolved with the use of specific ReFacto Laboratory Standard.

Aims: The aim of the study is to evaluate FVIII:C and recovery of EHL FVIIIs in spiked FVIII-deficient human plasma studies with four different type of assay.

Methods: The EHL-FVIII products tested were: Damoctocog alpha-pegol, Rurioctocog alpha-pegol, Turoctocog alpha-pegol and Efmoroctocog alfa. All EHL-FVIIIs were reconstituted according to the manufacturer's instructions and serial dilutions (1/0.5/0.1/0.05/0.025 U/mL) were obtained by using HemosIL® FVIII Deficient Plasma (Werfen). For each product, FVIII:C was then tested through OSA (Werfen), EHL-FVIII-calibrated OSA methods and two different commercially available CSA (Chromogenix Coamatic® Factor VIII and Trinichrom FVIII Stago).

Results: The classical OSA assay could show significant discrepancies between the nominal and real EHL-FVIII concentrations. The determination of Efmoroctocog alfa by OSA provides a value two-fold higher than the expected level. The calibrated-OSA assay is very accurate in determining the values of all EHL-FVIIIs, showing in the spiked experiments a drug recovery from 92% to 101%. On the contrary, the CSA, despite having been used to determine the potency of all products, reported very high CV (> 30%). Noteworthy, Jivi levels were significantly underestimated by one of the CSA tested, underestimating the nominal value up to 50%.

Conclusion(s): In this scenario, a standard calibration curve for each EHL-FVIII product could avoid inaccurate laboratory results, which might heavily impact on patient management.