INTRODUCTION:Although biomarkers are useful diagnostic tools to assess joint damage in osteoarthritis and rheumatoid arthritis, few data exist for biomarkers of haemophilic arthropathy.AIM:To evaluate the association between biomarkers and compatible additive magnetic resonance imaging (MRI) scores in patients with severe haemophilia A.METHODS:Patients aged 12-35 years with no history of factor VIII (FVIII) inhibitors were enrolled in a controlled, cross-sectional, multinational investigation. Patients received primary or secondary prophylaxis or on-demand treatment with FVIII and underwent MRI on four joints (two ankles, two knees). Soluble biomarkers of cartilage and bone degradation, inflammation, and angiogenesis were assessed (serum levels of C-terminal telopeptides of type I collagen [CTX-I], cartilage oligomeric matrix protein [COMP], chondroitin-sulphate aggrecan turnover 846 epitope [CS846], tissue inhibitor of metalloproteinase 1 [TIMP-1]; plasma levels of vascular endothelial growth factor [VEGF], matrix metalloproteinases 3 and 9 [MMP3, MMP9]). Relationships between biomarkers and MRI scores were evaluated using Spearman rank correlation.RESULTS:Biomarkers were assessed in 117 of 118 per-protocol patients. Mean and median CTX-I, COMP, TIMP-1, MMP3, MMP9, and VEGF values were within normal ranges (reference range not available for CS846 in healthy volunteers). No correlations between biomarkers and MRI scores were found, with the exception of CS846, which showed significant correlation in a subgroup of 22 on-demand patients (r = 0.436; P = 0.04).CONCLUSIONS:Compatible additive MRI scores showed no clear correlations with any of the potential biomarkers for haemophilic arthropathy in the overall population. CS846 levels were significantly correlated with MRI scores in patients treated on demand.

In patients with haemophilia A, factor VIII (FVIII) prophylaxis reduces bleeding frequency and joint damage compared with on-demand therapy. To assess the effect of prophylaxis initiation age, magnetic resonance imaging (MRI) was used to evaluate bone and cartilage damage in patients with severe haemophilia A. In this cross-sectional, multinational investigation, patients aged 12-35 years were assigned to 1 of 5 groups: primary prophylaxis started at age <2 years (group 1); secondary prophylaxis started at age 2 to <6 years (group 2), 6 to <12 years (group 3), or 12-18 years (group 4); or on-demand treatment (group 5). Joint status at ankles and knees was assessed using Compatible Additive MRI scoring (maximum and mean ankle; maximum and mean of all 4 joints) and Gilbert scores in the per-protocol population (n = 118). All prophylaxis groups had better MRI joint scores than the on-demand group. MRI scores generally increased with current patient age and later start of prophylaxis. Ankles were the most affected joints. In group 1 patients currently aged 27-35 years, the median of maximum ankle scores was 0.0; corresponding values in groups 4 and 5 were 17.0 and 18.0, respectively [medians of mean index joint scores: 0.0 (group 1), 8.1 (group 2) and 13.8 (group 4)]. Gilbert scores revealed outcomes less pronounced than MRI scores. MRI scores identified pathologic joint status with high sensitivity. Prophylaxis groups had lower annualized joint bleeds and MRI scores vs. the on-demand group. Primary prophylaxis demonstrated protective effects against joint deterioration compared with secondary prophylaxis.

SummaryThe safety and efficacy of a full-length sucrose-formulated recombinant factor VIII product (rFVIII-FS; KogenateFS; Kogenate Bayer) was evaluated in previously untreated (PUPs) and minimally treated (MTP) patients with severe haemophilia A (FVIII < 2%). Patients (37 PUPs; 24 MTPs) aged 0.1–25.7 months were treated with rFVIII-FS for a cumulative of 9,141 exposure days (EDs), median 114 EDs (range 4–478), on prophylactic or on-demand therapy. Eighty-nine percent of all treated bleeding episodes were successfully treated with 1 (74%) or 2 (15%) infusions. Clinical response to first infusion for each bleeding episode was rated as ‘excellent’ in 58%, or ‘good’ in 33%, of all cases. Recombinant FVIII-FS was used in 27 surgical procedures, mainly catheter implantations, which were all conducted without bleeding complications. FVIII recovery mean values (~2%/kg/ IU) were as expected for any licensed FVIII concentrate. FVIII neutralizing antibody formation was 15% (9/60). Aside from inhibitor formation, three adverse events were rated as ‘at least possibly drug-related’ for a total drug-related adverse event rate of 0.14%. No viral seroconversions were observed. Overall, excellent safety and efficacy were demonstrated with rFVIII-FS for therapy of young children with severe haemophilia A.

Full-length recombinant FVIII formulated with sucrose (rFVIII-FS; Kogenate FS; KOGENATE Bayer; KG-FS) is safe and efficacious when infused by bolus injection in patients with hemophilia A [1]. Administration of factor VIII (FVIII) by continuous infusion has certain advantages over intermittent bolus infusions or injections for prophylaxis against bleeding in the surgical setting and for prolonged therapy for severe bleeding episodes. Included in the advantages of continuous infusion are stability of plasma FVIII levels (elimination of plasma peaks and troughs), a reduction in overall quantity of FVIII required, and accordingly, potential cost benefits. A comprehensive review of continuous infusion was recently presented by Schulman [2]. This review compiled the data from a number of studies that compared bolus and continuous infusion therapies. A notable prospective study by Batarova and Martinowitz [3] compared the safety, efficacy, and factor requirements in 43 major surgical procedures performed in severe hemophilia patients with either bolus injections or continuous infusion. This study showed that continuous infusion of FVIII resulted in significantly higher nadir FVIII levels (P < 0.01), a significantly lower drop in hemoglobin levels (P < 0.05), significantly lower transfusion requirements (P < 0.01), and a significantly lower FVIII dosage (P < 0.01) compared with bolus injection. Successful continuous infusion requires product stability for extended periods of time (i.e. for the duration of the infusion). In the current study, the stability of reconstituted rFVIII-FS was assessed in a mini-pump infusion device (cassette, pump, tubing, etc.). The goal of the study was to obtain preliminary data prior to the initiation of clinical trials of rFVIII-FS in a continuous infusion setting. Product was delivered with a CADD-Prizm Variable Infusion Profile Pump equipped with a polyvinyl chloride medication bag (50 mL) and extension set (114 cm; 1.4 mL) (SIMS Deltec, Inc., St Paul, MN, USA.). FVIII coagulant activity was assessed with the one-stage clotting assay. Three different lots of rFVIII-FS were used. Samples (100 lL) were collected at timed intervals (with the initial time point immediately after the product had been placed into the feeding reservoir) for up to 72 h. The infusion rate chosen was 600 lL h. This correlates with the administration of 3.4 IU rFVIII h kg bodyweight for the 1000 IU per vial product based on a 70-kg person. For the 500 IU per vial product, a flow rate of 600 lL h correlates with a dose of 1.7 IU rFVIII h kg bodyweight based on a 70-kg person. The flow rate was kept constant for both concentrations to ensure the same instrumental conditions (particularly the surface-to-volume ratio and delay time in the system) over the entire time period of the experiment. Samples (100 lL) were collected in polypropylene vials and analyzed immediately. In a second experiment, using an identical experimental design but excluding the infusion pump, samples were collected over a 72-h period directly from the tube using a syringe. Recovery of rFVIII activity for all lots was similar, independent of the presence of the pump, and ranged from 80% to 110% of initial values over time. Stability was maintained for up to 72 h. A slight loss of activity was observed in the samples obtained in the first 2–3 h, most probably due to saturable adsorption of the rFVIII protein to the surface of the tubing and bag. After approximately one void volume (1.4 mL) had passed through the tubing, the activity measured in the obtained test samples returned to a normal level. In the experimental set-up without the pump, the slight loss of activity in the collected samples at the beginning was delayed by up to 4–5 h. This can be explained by a diffusion-controlled saturation of the tubing surface with rFVIII protein because of the lack of flow. Mean rFVIII activity values for the same lots were comparable in both experiments (with and without the pump). These stability results with Kogenate FS over 3 days are similar to those with Kogenate reported by Hurst et al. [4] with polyvinyl chloride bags. The reduced activity measured in Correspondence: Eduard Gorina, Bayer HealthCare, 4201 Research Commons, 79 T.W. Alexander, Research Triangle Park, NC USA. Tel.: 919 316 6452; fax: 919 316 6352; e-mail: eduard.gorina.b@ bayer.com

Treatment of previously untreated patients (PUPs) and minimally treated patients (MTPs) with severe hemophilia A using FVIII concentrates is complicated by FVIII inhibitor formation in ∼30% of patients. The incidence of FVIII inhibitors was determined in a prospective clinical trial of sucrose‐formulated full‐length recombinant FVIII (rFVIII‐FS, KOGENATE® Bayer; Kogenate® FS) in pediatric patients.Methods: PUPs and MTPs (=4 exposure days‐EDs) with hemophilia A (<2% FVIII) were enrolled from 19 EU and 13 US centers. Sixty patients were evaluable for inhibitor formation (EU, 31; US, 29). Patients were tested regularly with the Nijmegen‐modified Bethesda assay (negative, ≤0.6 BU; Low Titer, >0.6‐5 BU; High Titer, >5 BU).Results: In the EU cohort (31 Caucasian), 4 patients developed inhibitors (3 Low; 1 High). Five high titer inhibitors developed in the US cohort (17 Caucasian; 5 Black; 7 Other). Median EDs at inhibitor detection was 8 [range, 3‐16], and at study end 1 EU and 4 US patients had <20 EDs. The incidence of inhibitors in patients achieving 20 ED was 16.4% (9/55).Conclusions: The rate of inhibitor formation in pediatric patients with severe hemophilia A treated with rFVIII‐FS is consistent with that observed with plasma‐derived and other recombinant FVIII products. Major gene disruptions were observed in all inhibitor patients.

A sucrose‐formulated recombinant FVIII (rFVIII‐SF) was investigated under clinical trial conditions during surgical procedures in previously treated patients (PTPs). Fifteen PTPs with severe haemophilia A (FVIII ≤ 1%) underwent 22 surgical procedures. The procedures performed cover a spectrum from minor to major surgery. Haemostatic outcome was assessed by the investigators to be excellent in 16 procedures and good in the remaining six procedures. It is concluded that rFVIII‐SF is efficacious and safe in severe haemophilia A patients undergoing minor or major surgery.

To add an increased level of safety to antihemophilic factor replacement therapy, a full-length, recombinant Factor VIII (rFVIII) product has been developed without human-derived plasma proteins during purification and formulation and using an additional solvent/detergent viral inactivation step. This first clinical trial of a sucrose-formulated full-length rFVIII (rFVIII-FS) was conducted in previously treated patients (> or = 100 prior exposure days) with severe (<2% FVIII) hemophilia A in North America (NA) and Europe (EU). Pharmacokinetic profiles for rFVIII-FS were compared with those of currently licensed rFVIII product (Kogenate) in 35 patients. Safety and efficacy during home therapy were evaluated in 71 patients. The new formulation displayed a pharmacokinetic profile similar to that of rFVIII. Patients on home therapy received a cumulative total of 11,867 exposure days, 12,546 infusions, and 22,443,694 IU of rFVIII-FS. Of 2585 bleeds, 93.5% were treated with 1-2 infusions and 80.5% of responses were rated as excellent or good. No evidence of de novo inhibitor formation was observed. Only 0.27% of infusions were associated with any drug-related adverse event. Except for an episode of intermittent chest pain with palpitations which ceased after treatment with analgesics, associated adverse events were mild or moderate. Overall, rFVIII-FS provided excellent hemostatic control, was well-tolerated, and caused no significant adverse effects, thus demonstrating safety and efficacy for treatment of bleeds in patients with hemophilia A.