Factor VIII Products Research Articles

Factor VIII products and inhibitor development in previously treated patients with severe or moderately severe hemophilia A: a systematic review

Background Patients with severe hemophiliaA who have been treated extensively with factorVIII products have a low but potentially serious risk of inhibitor development. It is unknown why these patients develop inhibitors, and data on product-related immunogenicity are scarce. Aims To summarize the currently available evidence on the relationship between inhibitor development and recombinant FVIII product type in previously treated patients (PTPs) with severe hemophiliaA. Methods Longitudinal studies were included that reported on denovo inhibitor formation in patients with baseline FVIII activity levels of <0.02IUmL-1 who had been treated with FVIII for at least 50days. Pooled incidence rates of inhibitor development according to product types were calculated with a random intercept Poisson regression model. Results Forty-one independent cohorts were included; 39 patients developed denovo inhibitors during 19157person-years of observation. The overall incidence rate was 2.06 per 1000person-years, with a 95% confidence interval (CI) of 1.06-4.01. According to product type, the pooled incidence rates were 0.99 (95%CI0.37-2.70) per 1000person-years for patients treated with Advate, 5.86 (95%CI0.25-134.92) per 1000person-years for those treated with Kogenate/Helixate, 1.35 (95%CI0.66-2.77) per 1000person-years for those treated with KogenateFS/Helixate NexGen, 12.05 (95%CI1.53-94.78) per 1000person-years for those treated with Refacto, and 4.64 (95%CI0.82-26.43) per 1000person-years for those treated with RefactoAF. Conclusion These results suggest that some products may be associated with increased immunogenicity. However, the low incidence of inhibitors in PTPs and the differences in study design may cause significant variation in estimates of risk.

Comparative analysis of marketed factor VIII products: recombinant products are not alike vis‐a‐vis soluble protein aggregates and subvisible particles

Background Recombinant protein technologies have facilitated the development of novel factor VIII (FVIII) therapeutics with improved production efficiency, potency and half-live, and a low risk of viral transmission. The increasing number of recombinant FVIII (rFVIII) products and information on their efficacy, safety and cost allow patients and healthcare professionals to adjust treatment to individual needs. Nonetheless, 20-32% of previously untreated patients with severe hemophilia A develop inhibitory antibodies to rFVIII following treatment. The root cause of the immunogenicity of rFVIII products is not well understood. Data for human interferon and human insulin products suggest that critical quality parameters such as soluble protein aggregates (SPAs) and subvisible particles (SVPs) influence the immunogenicity of protein therapeutics. Therefore, we analyzed SPA and SVP concentrations in commercially available rFVIII products and determined how these parameters change upon exposure of rFVIII products to relevant stress conditions. Objectives Compare critical quality parameters such as SPA and SVP concentrations in rFVIII products under intended use and use-relevant stress conditions. Methods Nine rFVIII products (≥ 3 lots each) were analyzed by high-performance liquid chromatography-size exclusion chromatography (HPLC-SEC) and flow cytometry-based particle analysis. Results/conclusions SPAs and SVPs were present at different concentrations in all freshly reconstituted rFVIII products: SPA concentrations ranged from 0.2% to 11.6%; SVPs were 0.7 × 106 to 114.0 × 106 / 1000 IU. Under use-relevant stress conditions (agitation and shear stress) the products formed additional SPAs and SVPs to different degrees. The collected data indicate that product quality determines its propensity to form SVPs and SPAs, and highlights differences between marketed rFVIII products.

Preclinical pharmacokinetics and biodistribution of subcutaneously administered glycoPEGylated recombinant factor VIII (N8‐GP) and development of a human pharmacokinetic prediction model

Background N8-GP is an extended half-life recombinant factorVIII (FVIII) for the treatment of hemophiliaA. Subcutaneous administration of FVIII may reduce the treatment burden of prophylaxis; however, standard FVIII products have low bioavailability after subcutaneous dosing in animals. Objective To evaluate the pharmacokinetics, effectiveness and local distribution of subcutaneously administered N8-GP in preclinical models and predict the human pharmacokinetic (PK) profile. Methods The pharmacokinetics of subcutaneously administered N8-GP were evaluated in FVIII knockout (F8-KO) mice and cynomolgus monkeys; a human PK prediction model in hemophiliaA patients was developed. The hemostatic effect was evaluated in a tail vein bleeding model in F8-KO mice. The injection-site distribution and absorption of subcutaneously administered N8-GP were assessed in F8-KO mice by the use of temporal fluorescence imaging and immunohistochemistry. Results Subcutaneously administered N8-GP had a bioavailability, a first-order absorption rate and a half-life, respectively, of 24%, 0.094h-1 and 14h in F8-KO mice, and 26%, 0.33h-1 and 15h in cynomolgus monkeys. A dose-dependent effect of subcutaneously administered N8-GP on blood loss was observed in mice. A minimal amount of N8-GP was detected at the injection site 48-72h after single or multiple dose(s) in F8-KO mice. Subcutaneously administered N8-GP was localized to the skin around the injection site, with time-dependent disappearance from the depot. PK modeling predicted that subcutaneously administered N8-GP at a daily dose of 12.5IUkg-1 will provide FVIII trough levels of 2.5-10% in 95% of patients with severe hemophiliaA. Conclusions Subcutaneously administered N8-GP may provide effective hemophiliaA prophylaxis. A phaseI clinical trial is underway to investigate this possibility.

Biochemical characterization and immunogenicity of Neureight, a recombinant full-length factor VIII produced by fed-batch process in disposable bioreactors

Hemophilia A is a X-linked recessive bleeding disorder consecutive to the lack of circulating pro-coagulant factor VIII (FVIII). The most efficient strategy to treat or prevent bleeding in patients with hemophilia A relies on replacement therapy using exogenous FVIII. Commercially available recombinant FVIII are produced using an expensive perfusion technology in stainless steel fermenters. A fed-batch fermentation technology was recently developed to produce ‘Neureight’, a full-length recombinant human FVIII, in Chinese hamster ovary (CHO) cells. Here, we investigated the structural and functional integrity and lack of increased immunogenicity of Neureight, as compared to two commercially available full-length FVIII products, Helixate and Advate, produced in baby hamster kidney or CHO cells, respectively. Our results demonstrate the purity, stability and functional integrity of Neureight with a standard specific activity of 4235 ± 556 IU/mg. The glycosylation and sulfation profiles of Neureight were similar to that of Advate, with the absence of the antigenic carbohydrate epitopes α-Gal and Neu5Gc, and with sulfation of Y1680, that is critical for FVIII binding to von Willebrand factor (VWF). The endocytosis of Neureight by human immature dendritic cells was inhibited by VWF, and its half-life in FVIII-deficient mice was similar to that of Advate, confirming unaltered binding to VWF. In vitro and in vivo assays indicated a similar immunogenicity for Neureight, Advate and Helixate. In conclusion, the production of full-length FVIII in a fed-batch fermentation mode generates a product that presents similar biochemical, functional and immunogenic properties as products developed using the classical perfusion technology.

Patient preferences in the treatment of hemophilia A: impact of storage conditions on product choice.

ObjectivesTo gain insights into the usage of factor VIII (FVIII) products by patients diagnosed with moderate/severe hemophilia A, and to assess the impact and perceived importance of product storage.MethodsIn this study, 200 patients diagnosed with moderate or severe hemophilia A across seven countries participated. Data were collected via a 30-minute, face-to-face interview in six countries and via a web-based survey in the seventh country. The questionnaire evaluated the effect of six features associated with FVIII products on the choice of the product; the structure and flow of data collection was designed to eliminate potential bias.ResultsTwo-thirds of the respondents were using recombinant FVIII products. Only 17% were generally dissatisfied with current FVIII products, whereas >40% of the respondents were dissatisfied with frequency of administration and storage issues when traveling. The majority noted restrictions in their daily activities, particularly travel and sports. Most of them (85%), stored their product in the refrigerator and of these, 88% believed that it should always be stored there. These patients were also less satisfied with the product overall, more concerned about storage temperature, more restricted in daily activities, and spent more time on preparation and injection compared with patients who stored their product at room temperature. Conjoint analysis revealed that origin of FVIII (plasma-derived vs recombinant) was the strongest driver of product choice among all respondents, followed by storage flexibility (temperature), reconstitution device, and administration frequency. In this study, we did not investigate the efficacy and safety of the product.ConclusionNot refrigerating FVIII products was associated with greater patient satisfaction and less restriction on daily activities. If efficacy and safety are unaffected, then storing FVIII at room temperature might have a positive impact on product choice. Few patients were aware that FVIII can be stored without refrigeration, suggesting that health care professionals who treat hemophilia should communicate this aspect to the patient (depending on the labeled option); this approach might offer patients greater flexibility when traveling and require less time for reconstitution.

Timing and severity of inhibitor development in recombinant versus plasma‐derived factor VIII concentrates: a SIPPET analysis

Background The development of neutralizing antibodies (inhibitors) against factor VIII (FVIII) is the most severe complication in the early phases of treatment of severe hemophilia A. Recently, a randomized trial, the Survey of Inhibitors in Plasma-Product Exposed Toddlers (SIPPET) demonstrated a 2-fold higher risk of inhibitor development in children treated with recombinant FVIII (rFVIII) products than with plasma-derived FVIII (pdFVIII) during the first 50 exposure days (EDs). Objective/Methods In this post-hoc SIPPET analysis we evaluated the rate of inhibitor incidence over time by every 5 EDs (from 0 to 50 EDs) in patients treated with different classes of FVIII product, made possible by a frequent testing regime. Results The highest rate of inhibitor development occurred in the first 10 EDs, with a large contrast between rFVIII and pdFVIII during the first 5 EDs: hazard ratio 3.14 (95% confidence interval [CI], 1.01-9.74) for all inhibitors and 4.19 (95% CI, 1.18-14.8) for high-titer inhibitors. For patients treated with pdFVIII, the peak of inhibitor development occurred later (6-10 EDs) and lasted for a shorter time. Conclusion These results emphasize the high immunologic vulnerability of patients during the earliest exposure to FVIII concentrates, with the strongest response to recombinant FVIII products.

Lonoctocog alfa (rVIII-SingleChain) for the treatment of haemophilia A

ABSTRACTIntroduction: The administration of factor VIII (FVIII) concentrates on-demand or on long-term prophylaxis is the effective and safe standard of care of patients with hemophilia A (HA). Development of neutralizing antibodies against exogenous FVIII and the short half-life of the current available products remain major challenges. There is currently a great interest towards newer FVIII products with the goal of reducing the inhibitor risk and increasing the half-life.Area covered: In this review, the authors describe the efficacy and safety of rVIII-SingleChain (Lonoctocog alfa), the first and only single chain recombinant FVIII (rFVIII) molecule developed for the prevention and treatment of bleeding episodes in HA patients. The pre-clinical and clinical studies of rVIII-SingleChain as well as the results of the AFFINITY trial program in previously treated patients both adults and pediatric are presented and discussed.Expert opinion: The results from PTP studies document the efficacy and safety profile of the rVIII-SingleChain. However, even if rFVIII-SingleChain presents advantageous pharmacokinetic features compared to conventional rFVIII, it should not be considered as an EHL-FVIII while its immunogenicity is currently being studied in PUPs. The slightly better PK profile of rFVIII-SingleChain could however allow a small number of selected patients to be treated with a less intensive regimen.

Real-World Health Care Expenditure In Hemophilia A Patients Using Standard And Extended Half-Life Recombinant Factor VIII Products

Management of hemophilia A includes replacement of factor VIII (FVIII) by intravenous infusion. The recent introduction of extended half-life (EHL) FVIII products has enabled comparison of health care expenditure and volumes of factor dispensed for hemophilia A patients switching from a standard half-life (SHL) to EHL FVIII product. The Truven Health MarketScan® Research US claims databases (Aug 1, 2014 to Jan 31, 2017) were used to identify direct expenditures and international units (IUs) dispensed for all patients who used SHL (SHL group) and/or EHL (EHL group). Data on patients who switched from an SHL to an EHL FVIII product were captured up to one year before and after the switch. Patients with at least 1 pre and post-calendar quarter of claims available were included in the switching analysis. Cross-sectional analysis: In the SHL group (N=415), Six distinct SHL FVIII products were dispensed, with two EHL FVIII products dispensed in the EHL group (N=91). Median FVIII product dispensation per calendar quarter was 46,409 IU (IQR, 12,760-87,670 IU) (SHL) versus 67,375 IU (IQR, 50,524-98,264 IU) (EHL). Median expenditures per calendar quarter were higher for EHL ($135,519; IQR, $100,320-186,557) than for SHL ($61,152; IQR, $18,593-115,845). Switching analysis: In the EHL group, 29 patients switched from one of three SHL FVIII products to one of two EHL FVIII products during the study period. Total median IU dispensation per calendar quarter increased following the switch from 58,598 IU (pre-switch, SHL) to 68,036 IU (post-switch, EHL; 16% increase). Factor-related expenditure also increased 84% ($76,553, SHL, versus $141,101, EHL). This analysis suggests that switching from an SHL to an EHL product is associated with increased IU dispensation, expenditures and variability, including more EHL IU dispensed post-switch than SHL in quarters pre-switch. Further real world analyses incorporating larger numbers of patients should be explored.

Annual Economic Comparison of Prophylactic Treatment of Severe Haemophilia A In Spain

Haemophilia A is a genetic disorder characterized by deficiency in factor VIII (FVIII), how frequently a person bleeds and its severity depends on how much FVIII is in the plasma. Consequently, severe Haemophilia A is a lifelong condition that requires treatment with exogenous FVIII. Reduction of bleeding and chronic joint disease is achieved by prophylactic treatment. Several recombinant FVIII products (BAY 81-8973 and BIIB-031) have been recently approved introducing new dose frequency intervals. The aim of this study is to compare prophylactic treatments costs of recombinant FVIII products. The annual costs have been calculated according to the different prophylactic doses of recombinant FVIII products, based on the Summary of Product Characteristics (SmPCs), for adults and adolescents aged 12 and over, with an average weight of 70kg. The number of units of FVIII is expressed in International Units (IU). Prophylactic treatment with BAY 81-8973 (20-40 IU/kg, 2-3 times weekly) was compared to prophylactic treatment with BIIB-031 (50 IU/kg, every 3-5 days) and rAHF-PFM (20-40 IU/kg, intervals of 2-3 days). The analysis was conducted from the Spanish National Health System perspective in a 1-year time horizon. Costs were based on the price per IU established in the reference price group in 2017 Euro (€). Over the time horizon evaluated, average prophylaxis cost per year was estimated at €180,739.10 with BAY 81-8973 treatment, compared with €211,441.58 for BIIB-031 and €211,441.58 for rAHF-PFM. The analysis conducted in this study concludes that the estimated annual prophylactic treatment of severe haemophilia A with BAY 81-8973 could be less expensive than other recombinant FVIII product at the same price per IU.

Lonoctocog Alfa: A Review in Haemophilia A.

Lonoctocog alfa (rVIII-SingleChain; Afstyla®) is a novel single-chain recombinant factor VIII (FVIII) molecule, with a truncated B-domain and the heavy and light chains covalently linked to form a stable and homogenous drug that binds with high affinity to von Willebrand factor (VWF). Intravenous lonoctocog alfa is approved for the prophylaxis and treatment of bleeding in patients with haemophilia A in several countries worldwide. In two pivotal, multicentre trials, lonoctocog alfa was effective in the treatment of bleeding episodes and as prophylaxis, including for perioperative management in adults, adolescents and children. In terms of haemostatic efficacy in controlling bleeding episodes, overall treatment and investigator-assessed success rates were high across all age groups, with the majority of these bleeds controlled with a single injection of lonoctocog alfa. Low median spontaneous, overall and traumatic annualized bleeding rates were evident with prophylactic lonoctocog alfa regimens in both trials. Lonoctocog alfa was generally well-tolerated, with very low rates of injection-site reactions. No previously treated patient experienced an anaphylactic reaction or developed an inhibitor. In conclusion, lonoctocog alfa is an effective and generally well-tolerated alternative to conventional FVIII products for the treatment and prophylaxis of bleeding, including in the surgical setting, in adults, adolescents and children with haemophilia A.

An Open-label, Single-dose, Pharmacokinetic Study of Factor VIII Activity After Administration of Moroctocog Alfa (AF-CC) in Male Chinese Patients With Hemophilia A

PurposeHemophilia A represents up to 80% of all hemophilia cases in China. In patients with this condition, bleeding can be prevented and controlled by administering clotting factor VIII (FVIII). Since their initial availability, recombinant FVIII products have undergone several iterations to enhance their safety. Moroctocog alfa albumin-free cell culture (AF-CC) is among the third generation of recombinant FVIII products and received regulatory approval in China in August 2012. The present study characterizes the single-dose pharmacokinetic parameters of FVIII activity (FVIII:C) after administration of moroctocog alfa (AF-CC) in male Chinese patients with hemophilia A. MethodsThis multicenter, open-label, single-dose study enrolled 13 male Chinese patients diagnosed with severe hemophilia A (FVIII:C <1%) and a history of at least 150 exposure-days to any FVIII-containing product. Eligible patients received a single dose of moroctocog alfa (AF-CC) 50 IU/kg IV within 10 minutes. Blood samples were collected within 2 hours before administration and through 72 hours after dosing. FindingsPharmacokinetic parameters were assessed based on FVIII:C and were analyzed by age groups: ages 6 to <12 years (n = 3) and ≥12 years (n = 10). The mean plasma concentration-time profile for FVIII:C activity was consistently lower in patients aged 6 to <12 years compared with those aged ≥12 years. Geometric AUC0–∞ and Cmax were approximately 57% and 28% lower in the younger patients relative to the older patients, respectively. A total of 4 adverse events occurred in 4 patients. Low-titer, transient FVIII inhibitors were observed in 2 patients and were considered serious adverse events. Neither case resulted in clinical manifestations nor required treatment. ImplicationsThis is the first report of the pharmacokinetic parameters of FVIII:C after moroctocog alfa (AF-CC) in an all-Chinese population of males with hemophilia A. The pharmacokinetic profile in older patients was similar to that previously reported with recombinant FVIII products in studies with a predominantly white population; younger patients had reduced exposure to FVIII:C. The single doses of moroctocog alfa (AF-CC) were well tolerated; 2 cases of transient, low-titer FVIII inhibitor development were observed. ClinicalTrials.gov identifier: NCT02461992.

Many factor VIII products available in the treatment of hemophilia A: an embarrassment of riches?

Hemophilia A (HA) is a common bleeding disorder caused by the deficiency of factor VIII (FVIII) with an incidence of ~1 in 5000 male births. Replacement of FVIII is necessary to prevent and treat bleeding episodes. However, with multiple new drugs in addition to old standards, choosing among the different FVIII treatment options is harder than ever. There are FVIII products that are plasma derived or recombinant, FVIII products designed to extend the half-life of FVIII, and the first single-chain FVIII product, recombinant factor VIII single chain (rFVIII-SC). As development of inhibitors to FVIII continues to be a major problem in the care of HA patients, recent studies showing lower rates of inhibitor development with plasma-derived FVIIII products versus recombinant FVIII products have made choosing among the many options now available even more complex. Although still unproven, extended half-life (EHL) products may provide the hope of decreased immunogenicity but need further testing in previously untreated patients (PUPs). This review highlights some of the differences between FVIII products currently available and hopefully assists the clinician to decide which FVIII product to choose for their patients.

Predicting dose sparing benefit and bleeding risk of pharmacokinetic-based personalized prophylactic dosing of factor VIII products.

Previously published factor VIII (FVIII) pharmacokinetic (PK)-based dosing approaches employ fixed infusion interval with a wide dose range that may lead to increased risk of bleeding, excessive doses or decreased health-related quality of life. The objectives of the study includes (i) personalizing infusion interval in lieu of fixed infusion, (ii) constraining dose within the range of 10-50IU/kg and (iii) characterizing bleeding risk of PK-based dosing in comparison with empiric standard doses. Patient demographics and PK parameters for conventional FVIII products were obtained from published literatures. Subject-specific PK parameters were derived from FVIII activities vs time data generated through simulation. Our data indicated approximately 4%, 38%, 37% and 20% of the subjects can be dosed with infusion interval of every 24, 48, 72 and 96hours, respectively, for maintaining a target 1IU/dL FVIII level within the dose range of 10-50IU/kg. Maintaining an alternative trough value of 3 or 5IU/dL requires more frequent infusion. The predicted median probability of bleeding risk per year was 35.7% (range, 11%-49%) for PK-based dosing maintaining 1IU/dL. Predicted median bleeding risk was 37.9% (0%-74%), 32.8% (0%-72%) and 26.7% (0%-70%) for standard dosing of 20, 30 and 50IU/kg, respectively. PK-based dosing resulted in a dose sparing benefit compared to standard dose of 30 or 50IU/kg three times per week. The results of the study demonstrate the feasibility of individualizing infusion interval, restricting FVIII dose, trough and peak concentration within an acceptable range.

First report on the safety and efficacy of an extended half-life glycoPEGylated recombinant FVIII for major surgery in severe haemophilia A.

N8-GP (turoctocog alfa pegol) is an extended half-life glycoPEGylated recombinant factor VIII (FVIII) product developed for the prevention and treatment of bleeds in haemophilia A patients. This is a planned interim analysis of pathfinder™3, an international, open-label, Phase 3 trial evaluating the efficacy and safety (including immunogenicity) of N8-GP administered before, during and after major surgery in severe haemophilia A patients aged ≥12 years. Sixteen patients who underwent 18 major surgical procedures (including synovectomy, joint replacement and ankle arthrodesis) were included here. Postoperative assessments were conducted daily for days 1-6, and once for days 7-14. Primary endpoint was N8-GP haemostatic efficacy, assessed after completion of surgery using a four-point scale ('excellent', 'good', 'moderate', 'none'). Haemostasis was successful (rated 'excellent' or 'good') on completion of surgery in 17 (94.4%) procedures and rated as 'moderate' (5.6%) for one surgery in a patient with multiple comorbidities who needed an intraoperative N8-GP dose (20.7 IU kg-1 ). In the postoperative period, three bleeds occurred (one during days 1-6; two during days 7-14); all were successfully treated with N8-GP. Mean N8-GP consumption on day of surgery was 80.0 IU kg-1 ; patients received a mean of 1.7 doses (median: 2, range: 1-3). No safety concerns were identified. The data showed that N8-GP was effective and well tolerated for the prevention and treatment of bleeds during major surgery; such FVIII products with extended half-lives may modify current treatment schedules, enabling fewer infusions and earlier patient discharge.

Population pharmacokinetic characterization of BAY 81-8973, a full-length recombinant factor VIII: lessons learned - importance of including samples with factor VIII levels below the quantitation limit.

The pharmacokinetics (PK), safety and efficacy of BAY 81-8973, a full-length, unmodified, recombinant human factor VIII (FVIII), were evaluated in the LEOPOLD trials. The aim of this study was to develop a population PK model based on pooled data from the LEOPOLD trials and to investigate the importance of including samples with FVIII levels below the limit of quantitation (BLQ) to estimate half-life. The analysis included 1535 PK observations (measured by the chromogenic assay) from 183 male patients with haemophilia A aged 1-61 years from the 3 LEOPOLD trials. The limit of quantitation was 1.5 IU dL-1 for the majority of samples. Population PK models that included or excluded BLQ samples were used for FVIII half-life estimations, and simulations were performed using both estimates to explore the influence on the time below a determined FVIII threshold. In the data set used, approximately 16.5% of samples were BLQ, which is not uncommon for FVIII PK data sets. The structural model to describe the PK of BAY 81-8973 was a two-compartment model similar to that seen for other FVIII products. If BLQ samples were excluded from the model, FVIII half-life estimations were longer compared with a model that included BLQ samples. It is essential to assess the importance of BLQ samples when performing population PK estimates of half-life for any FVIII product. Exclusion of BLQ data from half-life estimations based on population PK models may result in an overestimation of half-life and underestimation of time under a predetermined FVIII threshold, resulting in potential underdosing of patients.

Efficacy and safety of a recombinant factor VIII produced from a human cell line (simoctocog alfa)

ABSTRACTIntroduction: The development of inhibitors against infused factor VIII (FVIII) has a detrimental impact on health and quality of life of patients with hemophilia A. Several observational studies and a recently published randomized trial indicate that the inhibitor risk in previously untreated patients (PUPs) is higher following the use of recombinant FVIII (rFVIII) products compared with plasma-derived FVIII concentrates. There is currently a great interest towards newer rFVIII products that adopt various technological solutions to reduce the inhibitor risk.Areas covered: This review describes the efficacy and safety of simoctocog alfa (Nuwiq), a human cell-line derived rFVIII developed for the prevention and treatment of bleeding in hemophilia A patients. Particular relevance will be given to the safety aspects of this product, with special emphasis on the rate of inhibitor development, presenting the results of the phase II and III clinical trials on previously treated patients (PTPs) and the interim data from the phase III trial on PUPs.Expert opinion: The final results from PTP studies and the preliminary data from the PUP study document the high efficacy and safety profile of this rFVIII product, which has the potential to reduce the inhibitor risk in PUPs with severe hemophilia A.

Clinical evaluation of glycoPEGylated recombinant FVIII: Efficacy and safety in severe haemophilia A

Turoctocog alfa pegol (N8-GP) is a novel glycoPEGylated extended half-life recombinant factor VIII (FVIII) product developed for prophylaxis and treatment of bleeds in patients with haemophilia A, to enable higher activity levels with less frequent injections compared with standard FVIII products. This phase III (NCT01480180), multinational, open-label, non-randomised trial evaluated the safety and clinical efficacy of N8-GP when administered for treatment of bleeds and for prophylaxis, in previously treated patients aged ≥12 years with severe haemophilia A. Patients were allocated to receive N8-GP for prophylaxis or on-demand treatment for up to 1.8 years. Patients on prophylaxis were administered one dose of 50 IU/kg of N8-GP every fourth day. Bleeds were treated with doses of 20-75 IU/kg. Total exposure to N8-GP in the trial was 14,114 exposure days (159 patient-years). For the prophylaxis arm (n=175), the median annualised bleeding rate (ABR) was 1.33 (interquartile range, 0.00-4.61), the mean ABR was 3.70 (95 % confidence interval 2.94-4.66) and 70 (40 %) patients had no bleeds during the trial. Across treatment arms, 83.6 % of bleeds resolved with one injection and 95.5 % with up to two injections. N8-GP had a favourable safety profile and was well tolerated. The frequency and types of adverse events reported were as expected in this population. One patient developed inhibitory antibodies against FVIII (≥0.6 Bethesda units [BU]) after 93 N8-GP exposure days. No clinically significant safety concerns were identified and N8-GP was effective for prophylaxis and treatment of bleeds in previously treated patients.

Components in Plasma-Derived Factor VIII, But Not in Recombinant Factor VIII Downregulate Anti-Inflammatory Surface Marker CD163 in Human Macrophages through Release of CXCL4 (Platelet Factor 4)

Background: Hemarthrosis, or bleeding into the joints, is a hallmark of hemophilia. Heme triggers oxidative stress, inflammation, and destruction of cartilage and bone. The haptoglobin-CD163-heme oxygenase-1 (HO-1) pathway circumvents heme toxicity through enzymatic degradation of heme and transcription of antioxidant genes. Plasma-derived factor concentrates contain many proteins that might impact on cellular pathways in joints, blood, and vessels. Methods: Activation of platelets from healthy volunteers was assessed by flow cytometry analysis of fibrinogen binding and CD62P expression. Platelet CXCL4 release was measured by ELISA. Human peripheral blood mononuclear cells were exposed to CXCL4 or platelet supernatants (untreated or pre-stimulated with factor VIII (FVIII) products) during their differentiation to macrophages and analyzed for CD163 expression. Some macrophage cultures were additionally incubated with autologous hemoglobin for 18 h for analysis of HO-1 expression. Results: Platelet CXCL4 release was increased by all 8 tested plasma-derived FVIII products but not the 3 recombinant products. Macrophages exposed to supernatant from platelets treated with some plasma-derived FVIII products downregulated CD163 surface expression and failed to upregulate the athero- and joint protective enzyme HO-1 in response to hemoglobin. Conclusion: Plasma-derived FVIII products might promote bleeding-induced joint injury via generation of macrophages that are unable to counteract redox stress.

Appearance of High-Affinity Antibodies Precedes Clinical Diagnosis of FVIII Inhibitors - Preliminary Analysis from the Hemophilia Inhibitor PUP Study (HIPS)

Background and ObjectivesThe development of neutralizing antibodies (inhibitors) to factor VIII (FVIII) represents the major complication following replacement therapy with FVIII products in patients with hemophilia A. Why some patients develop FVIII inhibitors while others do not is poorly understood. Identification of early biomarkers which predict inhibitor development in previously untreated patients (PUPs) with hemophilia A will assist in risk identification and possible early intervention strategies. Previous analysis of FVIII-specific antibodies in different cohorts of patients with severe hemophilia A and in healthy individuals indicated distinct spectra of neutralizing and non-neutralizing antibodies (Whelan SFJ et al. Blood 2013). FVIII-specific antibodies found in hemophilia A patients with inhibitors have approximately 100-fold higher apparent affinities than that of antibodies found in patients without inhibitors or in healthy individuals (Hofbauer CJ et al. Blood 2015). In one individual, high affinity FVIII-specific antibodies were detectable prior to the diagnosis of FVIII inhibitors. The Hemophilia Inhibitor PUP Study (HIPS) is a prospective multicenter observational study of PUPs with severe hemophilia A during their first 50 exposure days (EDs) to recombinant FVIII (Advate TM). The objective is to elucidate immune system changes and identify potential early biomarkers of inhibitor development in PUPs. This is the first report of FVIII-specific antibody development in the first 10 subjects who have completed the study.MethodsHIPS study procedures have been previously described (Hofbauer CJ et al. 2015; clinicaltrials.gov NCT01652027). FVIII inhibitor testing by Nijmegen methodology performed in a central laboratory (Medical College of Vienna) and FVIII-specific antibody analytics were done prior to first exposure, 7-9 days after exposure day (ED) 1 and 5-7 days after EDs 5, 10, 20, 30, 40, and 50. FVIII-specific antibody analytics, including specifications of isotypes, IgG subclasses and apparent affinities were done using methodology described in Whelan 2013 and Hofbauer 2015.Results:Currently, 24 subjects have been enrolled among 19 study sites. Data for 10 subjects were available for analysis. Among these 10 subjects, 2 developed FVIII inhibitors by study criteria (B.U. > 0.6 B.U. x 2 measurements in central laboratory) by exposure days 6 and 20 (see figure 1). A third subject is expected to meet study criteria for FVIII inhibitor due to multiple high titer measurements reported over time at a local laboratory. All three inhibitor patients revealed antibody class switching from IgG1 to IgG4 and affinity maturation resulting in the generation of high affinity FVIII-specific antibodies. High-affinity FVIII-specific IgG1 antibodies were detectable prior to inhibitor diagnosis in all 3 inhibitor subjects.One subject with a transient FVIII inhibitor showed medium affinity FVIII-specific IgG1 antibodies which persisted until ED50, but never developed high-affinity antibodies. Another subject without a detectable inhibitor developed low titer, low affinity IgG1 antibodies that persisted to ED 50 without the development of high-affinity antibodies. The remaining subjects had no inhibitor and no detectable FVIII-specific antibodies.Conclusions:Interim data from HIPS suggests that FVIII inhibitor development is preceded by the detection of high-affinity FVIII-specific antibodies which undergo class switch from IgG1 and IgG3 to IgG4.The findings confirm affinity maturation of FVIII-specific antibodies which require T-cell dependent antibody responses resulting from germinal center reactions. While low affinity IgG1 antibodies were sometimes seen in subjects without inhibitors, high-affinity antibodies were only seen in subjects who developed inhibitors. Our data indicate that high affinity FVIII-specific antibodies preceded the clinical diagnosis of an inhibitor and may serve as early biomarkers of FVIII inhibitor development facilitating early immune intervention. [Display omitted] DisclosuresReipert:Shire: Employment, Research Funding. Gangadharan:Shire: Employment, Research Funding. Hofbauer:Shire: Employment. Scheiflinger:Shire: Employment, Research Funding. Bowen:Baxalta: Research Funding. Donnachie:Baxalta: Research Funding; CSL Behring: Research Funding; Bayer Healthcare: Research Funding. Fijvandraat:CSL Behring: Research Funding; Bayer Healthcare: Research Funding; Baxalta: Membership on an entity's Board of Directors or advisory committees. Gruppo:Baxalta: Honoraria, Membership on an entity's Board of Directors or advisory committees. Male:Baxalta: Other: travel support; Novo Nordisk: Other: travel support; Biotest: Other: travel support; Bayer Healthcare: Other: travel support; CSL Behring: Other: travel support; Pfizer: Other: travel support. McGuinn:Baxalta: Research Funding; Novo Nordisk: Research Funding; Spark: Research Funding; Biogen: Research Funding. Meeks:Genentech: Membership on an entity's Board of Directors or advisory committees; Bayer Healthcare: Membership on an entity's Board of Directors or advisory committees; Grifols: Membership on an entity's Board of Directors or advisory committees; Biogen: Membership on an entity's Board of Directors or advisory committees; CSL Behring: Membership on an entity's Board of Directors or advisory committees; Shire: Membership on an entity's Board of Directors or advisory committees. Recht:Novo Nordisk: Consultancy, Research Funding; Baxalta: Research Funding; Biogen Idec: Research Funding; Kedrion: Consultancy. Ragni:Biogen: Research Funding. Yaish:Octapharma: Consultancy; Bayer Healthcare: Consultancy; Baxalta: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Santagostino:Sobi: Consultancy; Biogen Idec: Consultancy; Novo Nordisk: Consultancy; Pfizer: Consultancy; Octapharma: Consultancy; Baxalta: Consultancy; Kedrion: Consultancy; CSL Behring: Consultancy; Bayer: Consultancy; Grifols: Consultancy; Roche: Consultancy. Brown:Baxalta/Shire: Research Funding.

Bay 94-9027, a Site-Specifically Pegylated Recombinant Factor VIII: Preliminary Results from an International Comparative Laboratory Field Study

Introduction: Accurate measurement of factor VIII (FVIII) in patients with hemophilia A after infusion of FVIII is important for patient monitoring and treatment decisions. Discrepancies in results using different assays or reagents to measure prolonged-half-life factor products have been recognized and highlight that effective monitoring of patient response to these products may require adjustments in clinical laboratory practices. Because of this recognized issue, a global field study was conducted to assess the ability of clinical laboratories to measure BAY 94-9027 activity in spiked hemophilic plasma samples using their in-house or specific assays. BAY 94-9027 is a prolonged-half-life FVIII that has been modified through site-specific addition of a 60-kDa polyethylene glycol (2×30 kDa branched).Methods: Participating laboratories received sample sets of 26 blinded samples each in randomized order for analysis; 3-4 sample sets were provided to each laboratory to complete the study. Each set consisted of triplicate BAY 94-9027 or a comparator (antihemophilic factor [recombinant] plasma/albumin-free method [rAHF-PFM (Advate®); Shire, Westlake Village, CA, USA]) spiked at low (<10 IU/dL), medium (10-50 IU/dL), and high (50-100 IU/dL) concentrations in pooled hemophilic plasma. BAY 94-9027 and rAHF-PFM both use the chromogenic assay for potency labeling. Normal control plasma and unspiked pooled hemophilic plasma in triplicate served as positive and negative controls, respectively. Two additional blinded samples matching 2 of the other 24 samples in the set were included in each set to decrease the predictability of the sample sets and prevent observer bias. In the first stage of the study, laboratories analyzed test samples using their in-house assays, reagents, and standards. Laboratories that had the capability to use the chromogenic assay also measured an additional sample set using the chromogenic assay. In the second stage of the study, all participating laboratories tested 2 additional sample sets using 2 Bayer-provided activated partial thromboplastin time (aPTT) kits (Pathromtin® [Siemens, Marburg, Germany] and HemosIL® SynthASil [Instrumentation Laboratory, Bedford, MA, USA]), as these kits have previously been shown to accurately measure BAY 94-9027 and full-length FVIII. FVIII recovery and FVIII levels were primary and secondary endpoints, respectively. Results were analyzed for intra- and interlaboratory variation.Results: 52 laboratories in North America, Europe, and Israel participated in the field study. Of these, 49 laboratories tested samples using their in-house one-stage assay, 16 tested samples using the chromogenic assay, and 13 used both assays. The reagents routinely used for measuring FVIII activity varied among participating laboratories. Mean FVIII recovery ranged from 75.1%–103.2% for BAY 94-9027 and 94.6%–114.7% for rAHF-PFM across all concentrations and reagents using the one-stage assay. As expected, the PTT-A (Stago, Asnières sur Seine, France) and HemosIL® APTT-SP kits (Instrumentation Laboratory), used by 6 and 2 laboratories, respectively, underestimated BAY 94-9027 at all concentrations. More accurate one-stage results were generated using the Pathromtin® and HemosIL® SynthASil kits, used by 6 and 15 laboratories, respectively, as shown in the second stage of the study. For the chromogenic assay, mean FVIII recovery ranged from 104.4%–117.1% for BAY 94-9027 and 87.7%–107.8% for rAHF-PFM across all concentrations. Interlaboratory variability was low for measurement of BAY 94-9027 with chromogenic assays (particularly Chromogenix Coamatic® and HemosIL® ELECTRACHROME™ [Instrumentation Laboratory]).Conclusions: The results of this global field study indicate that chromogenic assays are an accurate method for measurement of BAY 94-9027. BAY 94-9027 can also be accurately monitored using many commonly used one-stage assay kits, as gauged by their representation in the field study. Understanding the limitations and advantages of specific assay kits is important for choosing the correct assay systems to measure individual FVIII products in clinical practice. DisclosuresChurch:Bayer: Employment. Leong:Bayer: Employment. Katterle:Bayer Pharma AG: Employment. Rao Danda:Bayer: Employment. Ulbrich:Bayer Pharma AG: Employment. Noerenberg:Bayer Pharma AG: Employment. Bruns:Bayer: Consultancy. Michaels:Bayer: Employment.