Recombinant factor VIII(rEVO Biologics, Inc.)

Around one third of boys with severe hemophilia A develop inhibitors (neutralizing antibodies) against their therapeutic factor VIII product. This adverse effect may result in more life-threatening bleeding, disability, impaired quality of life, and costly care. We compared the incidence of inhibitors in boys treated with the three factor VIII products most used in France: one plasma-derived (Factane) and two recombinant products (Advate and Kogenate Bayer). A previously untreated cohort of patients was created in 1994 to investigate risk factors for inhibitor development. We selected boys with severe hemophilia A (factor VIII <1 IU/dL) first treated with one of the three factor VIII products studied. Details of product infusions, inhibitor assays and main fixed and time-varying inhibitor risk factors were recorded for the first 75 exposure days. Three outcomes (all inhibitors, high-titer inhibitors and subsequently treated inhibitors) were analyzed by univariate and multivariate Cox models. We studied 395 boys first treated between 2001 and 2016 (131, 137, and 127 with Factane, Advate, and Kogenate Bayer, respectively). Clinically significant inhibitors were diagnosed in 121 patients (70 high-titer). The incidence of high-titer inhibitors was significantly associated with the factor VIII product received (P=0.005): the cumulative incidence at 75 exposure days was 12.7% (95% CI: 7.7-20.6) with Factane, 20.4% (95% CI: 14.0-29.1) with Advate, and 31.6% (95% CI: 23.5-41.7) with Kogenate Bayer. The low inhibitor incidence observed with Factane is concordant with recent findings from the SIPPET randomized trial. These consistent results from observational and experimental studies should lead to improved care for previously untreated patients and cost savings for healthcare systems worldwide.

Background and Objectives  We studied the structural and functional properties of von Willebrand factor (VWF) molecules present in a very high‐purity plasma‐derived factor VIII concentrate (VHP pdFVIII – Factane®) because several observations suggest that the presence of VWF in factor VIII (FVIII) preparations may decrease their immunogenicity.Materials and Methods  Ten marketed batches of VHP pdFVIII (Factane®) with levels of VWF ranging from 15 to 39 IU/100 IU FVIII were analysed. The VWF multimeric pattern was studied by agarose gel electrophoresis. The binding of VWF to FVIII was studied by gel filtration and ELISA. The binding of VWF to GPIb was analysed by ELISA.Results  The results showed that high‐molecular‐weight multimers of VWF were present in VHP pdFVIII (Factane®). VWF subunits maintain a triplet structure similar to that of normal plasma. Regardless of the VWF content, all FVIII molecules of each batch were co‐eluted with VWF, and no free FVIII was detectable. By immunoassays, VWF was found to be able to bind to FVIII and platelet GPIb in a similar manner to that of VWF in normal plasma.Conclusions  In all the VHP pdFVIII (Factane®) batches studied, regardless of the level of VWF, the structure and capacity of VWF binding to FVIII and to platelet GPIb were fully preserved.