Objective:
Baxter has developed BAX 855, a PEGylated form of Baxter’s recombinant full length FVIII (rFVIII) product based on the ADVATETM manufacturing process. Here we describe it ́s manufacturing and structural and functional characterization.
Methods:
A rFVIII intermediate of the ADVATETM manufacturing process is the starting material for the conjugation process for preparing BAX 855 by proprietary PEGylation technology from Nektar Therapeutics. Similar technology has been successfully employed for marketed and licensed PEGylated drug products and drugs in clinical use. The manufacturing process for BAX 855 comprises several steps, including controlled PEGylation followed by cation exchange chromatography. Final formulation uses the same excipients as ADVATETM. BAX 855 was characterized by a number of analytical methods, focusing on the elucidation of the primary structure, posttranslational modifications, PEGylation site distribution and three- dimensional structure. The overall hemostatic potency of BAX 855 in FVIII-deficient plasma was assessed by conventional FVIII 1-stage clotting and chromogenic assays and with a thrombin generation assay. The tenase cofactor activity of FVIII was determined by measuring the kinetics of FXa generation. Binding of BAX 855 in comparison to ADVATETM was determined to its ligands VWF and low-density lipoprotein-receptor-related protein (LRP).
Summary and Conclusions:
BAX 855 is a full-length rFVIII with extended half-life. PK studies in different animal species and humans with hemophilia A display longer survival of BAX 855 compared to ADVATETM. The product is based on the original, native FVIII protein utilized in the production of ADVATETM. Our analyses show that BAX 855 can be manufactured reproducibly without changes to the protein structure characteristic for a fully functional full-length rFVIII molecule. The process is suited to manufacture BAX 855 in large scale and showed a good batch to batch consistency, ensuring an equivalent product quality for each batch. BAX 855 has a specific activity similar to that of rFVIII in ADVATETM and PEGylation degrees in the range of 2 to 3 mol PEG / mol rFVIII. SDS-PAGE and Western blot analysis of BAX 855 confirm PEGylation and demonstrate an increase in the molecular weight of the various FVIII domains.
In comparison to ADVATETM the functional properties of BAX 855 were fully retained except for binding to LRP, indicating that PEGylation did not have an impact on the functional properties of rFVIII. The latter might explain why BAX 855 shows prolonged survival in the circulation of hemophilic species and patients with hemophilia A than ADVATETM.
Objective:
To assess treatment of young adult (YA) patients with hemophilia (PWH) and issues around access to and use of factor and comprehensive care.
Methods:
Analysis of US respondents aged 18-30 years in the international HERO study conducted in 2010-2011.
Summary:
Of 189 adult PWH HERO respondents in the United States, 66 were aged 18-30 years. More YA-PWH were on prophylaxis (50%) than on-demand alone (24%) or with occasional short-term prophylaxis (24%). Only 27% used treatment medication exactly as prescribed, with 27% a little less, and 21% varying (sometimes more/less). Twenty-six percent reported issues with access to factor in the prior 5 years due to availability or affordability, with 82% citing financial issues. YA-PWH reported a median of 2 bleeds in the prior month and median (IQR) annual bleed rate of 9.5 (12-22) bleeds. Similar to older adults, 80% of YA-PWH reported that a single joint suffers more bleeds than others; the most common joints reported were the ankle (77%), elbow (26%), and knee (21%). YA-PWH rated perceived disease control (1-10 scale, 10=most control) as median (IQR) 8 (7-9). HTC visit frequency was median (mean) 1 (1.66) per year. Similar to older adults (aged >40 years), 21% of YA-PWH reported difficulty in visiting the HTC. Accessibility was the most common reason (79%)—distance to travel (57%) or time to travel (29%); time constraints were more commonly reported by YA-PWH (57%), including being unable to get time off work (50%). When identifying health care professionals (HCPs) involved in management of their hemophilia, YA-PWH named hematologists (83%), nurses (67%), social workers (48%), counselors/psychologists (30%), and physical therapists (26%). The majority were satisfied with care provided by HCPs. YA-PWH reported being very/somewhat knowledgeable about hemophilia (91%). When looking to the future (pessimistic=1 to optimistic=7), YA-PWH were generally optimistic, with median (IQR) 5 (5-7).
Conclusions:
YA-PWH in the United States are more likely to be on prophylaxis than older adults, but less likely to use medication exactly as prescribed. Additional research is warranted to better understand why prescribed regimens are not followed. Despite 50% prophylaxis use, bleeding occurred ~1-2 times/month and YA-PWH reported high perceived disease control. During this period of transition to independence, it is important to note one quarter reported issues around access to treatment and one fifth reported difficulty in visiting the HTC. YA-PWH were satisfied with care, but infrequently reported social workers and physical therapists as part of management.
