Essentials Data on product-related immunogenicity in previously treated haemophilia A patients is scarce. A systematic review and meta-analysis of all currently available evidence was conducted. The overall incidence rate was 2.06 per 1000 person-years (95% confidence interval: 1.06-4.01). Some recombinant factor VIII products were associated with increased immunogenicity.

The effect of recombinant factor VIII (rFVIII) brand on inhibitor development was investigated in all 407 severe hemophilia A previously untreated patients born in the United Kingdom (UK) between 1 January 2000 and 31 December 2011. Eighty-eight (22%) had been in the RODIN study. Information was extracted from the National Haemophilia Database. Because exposure days (EDs) were not known for some patients, time from first treatment was used as a surrogate for rFVIII exposure. An inhibitor developed in 118 (29%) patients, 60 high and 58 low titer, after a median (interquartile range) of 7.8 (3.3-13.5) months from first exposure and 16 (9-30) EDs. Of 128 patients treated with Kogenate Bayer/Helixate NexGen, 45 (35.2%, 95% confidence interval [CI] 27.4-43.8) developed an inhibitor compared with 42/172 (24.4%, 95% CI 18.6% to 31.4%) with Advate (P = .04). The adjusted hazard ratio (HR) (95% CI) for Kogenate Bayer/Helixate NexGen compared with Advate was 2.14 (1.12-4.10) (P = .02) for high titer and 1.75 (1.11-2.76) (P = .02) for all inhibitors. When excluding UK-RODIN patients, the adjusted HR (95% CI) for high-titer inhibitors was 2.00 (0.93-4.34) (P = .08). ReFacto AF was associated with a higher incidence of all, but not high-titer, inhibitors than Advate. These results will help inform debate around the relative immunogenicity and use of rFVIII brands.

Factor VIII is an important glycoprotein involved in hemostasis. Insertion of expression vectors containing either the full-length cDNA sequence of human factor VIII (FLrFVIII) or B-domain deleted (BDDrFVIII) into mammalian cell lines results in the production of recombinant factor VIII (rFVIII) for therapeutic usage. Three commercially available rFVIII concentrates (Advate, Helixate NexGen and Refacto), either FLrFVIII or BDDrFVIII, were investigated by 1- and 2-DE and MS. The objective of this study was to compare the heterogeneity and the high purity of both rFVIII preparations before and after thrombin digestion. In particular, the 2-D gel was optimized to better highlight the presence of contaminants and many unexpected proteins. Recombinant strategies consisting of insertion of expression vectors containing BDDrFVIII and FLrFVIII resulted in homogeneous and heterogeneous protein products, respectively, the latter consisting in a heterogeneous mixture of various B-domain-truncated forms of the molecule. Thrombin digestion of all the three rFVIII gave similar final products, plus one unexpected fragment of A2 domain missing 11 amino acids. Regarding the contaminants, Helixate NexGen showed the presence of impurities, such as Hsp70 kDa, haptoglobin and proapolipoprotein; Refacto showed glutathione S-transferase and beta-lactamase, whereas Advate apparently did not contain any contaminants. The proteomic approach will contribute to improving the quality assurance and manufacturing processes of rFVIII concentrates. In this view, the 2-DE is mandatory for revealing the presence of contaminants.

Sucrose-formulated octocog alfa (Kogenate Bayer, Kogenate FS, Helixate FS, Helixate nexgen) is a full-length recombinant human coagulation factor VIII (FVIII) product that is purified and formulated without the addition of human serum albumin and is stabilized with sucrose. The purification process of this formulation includes a solvent/detergent viral inactivation step. Sucrose-formulated octocog alfa is approved in the EU and US for the treatment of bleeding in patients with haemophilia A (congenital FVIII deficiency). Additionally, it is approved in the EU for the prophylaxis of bleeding in patients with haemophilia A and as a continuous infusion treatment in patients undergoing major surgery. Sucrose-formulated octocog alfa is effective and well tolerated as a FVIII replacement therapy in patients with haemophilia A, including those with severe disease undergoing major surgery. The therapeutic profile of this sucrose-formulated product cannot be compared with that of other octocog alfa or moroctocog alfa products because of a lack of head-to-head comparative studies. Pathogen transmission has not been reported with use of sucrose-formulated octocog alfa. Available data indicate that sucrose-formulated octocog alfa is an appropriate alternative to other recombinant FVIII products for the treatment and prophylaxis of bleeding episodes in adults and children with haemophilia A.