Validation of factor VIII activity for monitoring standard and extended half‐life products and correlation to thrombin generation assays

Abstract

Introduction Monitoring replacement therapy with standard and extended half‐life (EHL) products is challenging, since one‐stage assay (OSA) and chromogenic substrate assay (CSA) results may differ significantly. Recent recommendations include local validation of each new product with recovery within 20–30%, depending on activity level. Aim To validate factor VIII (FVIII) activity for monitoring products in clinical use on Atellica Coag and to correlate it with thrombin generation. Methods Plasma samples spiked with Advate®, Elocta®, Adynovi®, Nuwiq®, NovoEight® and Afstyla® (0.05, 0.20, 0.50 and 0.80 IU/ml) were analysed using Atellica Coag 360 with CSA‐1 (Coatest SP) and CSA‐2 (FVIII chromogenic), and OSA (Actin FS). Thrombin generation was performed using two thrombin generation assays (TGA‐1 (Thrombinoscope) and TGA‐2 (Technothrombin). Results All products at levels above 0.05 IU/ml, except Adynovi, showed acceptable recovery using CSA‐1, whereas measurements using CSA‐2 gave more results outside the target level. All products, except Afstyla, showed acceptable recovery using OSA. Correlation between CSA‐1 and OSA was excellent (r2=1.0) with biases of 6–3​2%, depending on FVIII product. A clear dose‐response was seen for all thrombin generation parameters and products using both methods, except at low levels for lag time using TGA‐1. With CSA‐1 as an independent variable, the correlations to thrombin peak (measured with TGA‐2) were good (r2 = .8–.9). Conclusion Our data revealed good correlation and acceptable bias between CSA and OSA using our sets of reagents, methods and analyser in spiked samples. Thrombin generation gave good correlation to CSA‐1 factor activity and is a possible complement to factor activity assays.

Evaluation of the Atellica COAG 360 coagulation analyzer in a specialized coagulation laboratory

“…However, the CSA‐2 could be useful when assaying post‐infusion samples of patients given EHL products. 5 , 19 …”

“… 3 The need for CSA and OSA for factor activity measurement of FVIII and FIX is also demonstrated by assay discrepancy seen for extended half‐life (EHL) products, which was covered previously. 5 , 6 , 7 , 8 While high‐throughput and short turnaround times are essential requirements for coagulation analyzers in routine laboratories, the requirements for specialized laboratories that provide services to a hemophilia treatment center (HTC) are somewhat different. Besides correct phenotype and severity classification for hereditary bleeding disorders, testing also involves diagnosing acquired or treatment‐induced bleeding conditions, some of which are considered critical hemostasis tests (i.e., anti‐FXa activity for heparin/low molecular weight heparin [LMWH]).…”

“… 10 The performance of OSA and CSA methods has also been tested for hemophilia replacement therapy with different EHL products using Atellica COAG 360. 5 , 11 …”

Thrombin generation for monitoring hemostatic therapy in hemophilia A: A narrative review

“…Multiple studies have shown a strong correlation between FVIII activity level and TG parameters (except for lag time) 4,5,21,24–28 . Despite these correlations, a wide inter‐patient variability in TG was observed when measured at different time points following a standard infusion of FVIII concentrate 4,21,24 .…”

“…Multiple studies have shown a strong correlation between FVIII activity level and TG parameters (except for lag time). 4 , 5 , 21 , 24 , 25 , 26 , 27 , 28 Despite these correlations, a wide inter‐patient variability in TG was observed when measured at different time points following a standard infusion of FVIII concentrate. 4 , 21 , 24 However, the intra‐patient variability was small, resulting in a predictable relation between FVIII and TG for an individual patient.…”