Safety of coagulation factor concentrates

Two-Step Size-Exclusion Nanofiltration of Prothrombin Complex Concentrate Using Nanocellulose-Based Filter Paper

Coagulation Factor IX-rich protrhombin complex concentrate (FIX-PCC) is a therapeutic biologic product that consists of a mixture of several human plasma-derived proteins, useful for treating hemophilia B. Due to its complex composition, FIX-PCC is very challenging to bioprocess through virus removing nanofilters in order to ensure its biosafety. This article describes a two-step filtration process of FIX-PCC using a nanocellulose-based filter paper with tailored porosity. The filters were characterized with scanning electron microscopy (SEM), cryoporometry with differential scanning calorimetry, and nitrogen gas sorption. Furthermore, in order to probe the filter's cut-off size rejection threshold, removal of small- and large-size model viruses, i.e., ΦX174 (28 nm) and PR772 (70 nm), was evaluated. The feed, pre-filtrate, and permeate solutions were characterized with mass-spectrometric proteomic analysis, dynamic light scattering (DLS), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and analytical size-exclusion high-performance liquid chromatography (SEHPLC). By sequential filtration through 11 μm pre-filter and 33 μm virus removal filter paper, it was possible to achieve high product throughput and high virus removal capacity. The presented approach could potentially be applied for bioprocessing other protein-based drugs.

A multianalytical approach to investigate the effect of nanofiltration on plasma-derived factor IX clinical lots

Plasma-derived proteins are a subset of relevant biotherapeutics also known as "well-characterized biologicals". They are enriched from plasma through several steps of physical and biochemical methodologies, reaching the regulatory accepted standards of safety, levels of impurities, activity and lot-to-lot consistency. Final products accepted for commercialization are submitted to tight analytical, functional and safety controls by a number of different approaches that fulfill the requirements of sensitivity and reliability. We report here the use of a multianalytical approach for the comparative evaluation of different lots of Factor IX isolated from plasma preparations and submitted or not to a step of nanofiltration. The approach include, among the other, proteomic techniques based on both MALDI-TOF and LC-MS Orbitrap mass spectrometry, circular dichroism for structural characterization, chromatographic and electrophoretic techniques, ELISA and functional assays based on clotting activity and binding to known anticoagulants. Comparative data obtained on two sets of nanofiltered and non-nanofiltered lots with different final activity show that the products have substantially overlapping profiles in terms of activity, contaminants, structural properties and protein content, suggesting that the proposed multianalytical approach is robust enough to be used for the routine validation of clinical lots.

Clinical assessment of Optivate®, a high-purity concentrate of factor VIII with von Willebrand factor, in the management of patients with haemophilia A

Summary.  Factor VIII (FVIII) concentrates have revolutionized the treatment of patients with haemophilia A. Concerns over the transmission of viral infections through these products have been addressed through stringent, donor‐screening procedures and robust antiviral manufacturing steps. Bio Products Laboratory has developed a high‐purity FVIII product with von Willebrand factor, Optivate^®. Its safety, tolerability and efficacy as prophylaxis and treatment of bleeds have been established in long‐term studies. Seventy previously treated patients with severe haemophilia A, with ≥20 exposure days, were recruited into two long‐term, multicentre, open‐label studies. The protocols were virtually identical. Patients received Optivate^® either prophylactically or on‐demand. A mean of 159.0 EDs were experienced over 11 320 infusions. Under both conditions, Optivate^® was well tolerated. Only 10% of patients experienced a treatment‐related adverse event; the most commonly reported were headache (4% of patients) and dizziness (3% of patients). The mean number of bleeds/patient over the 2 year treatment period was 23.5 during prophylactic use and 70.4 during on‐demand use. In patients treated prophylactically, clinical responses to breakthrough bleeds were rated by physicians as excellent or good and as very helpful or helpful by patients in 95% of bleeds. Clinical responses for on‐demand patients were rated as excellent or good by physicians and helpful or very helpful by the patients for 91% of bleeds. There were no viral transmissions or inhibitors. The studies confirm the clinical efficacy and safety of Optivate^® in both prophylactic and on‐demand management of patients with haemophilia A.

Factor replacement therapy in haemophilia--are there models for developing countries?

Successful models for factor replacement in severe haemophilia involves prophylactic or on-demand administration of large quantities (1500-9000 IU kg-1 year-1) of very high purity factor concentrates starting early in life. The prohibitive cost of these protocols make them completely impractical in developing countries where the quantity of factor used for replacement therapy is much lower and varies considerably (25-500 IU kg-1 year-1). At this level of treatment, as some joint damage is inevitable, the aim of therapy shifts to preventing disability and preserving reasonable joint function rather than perfect architecture. There are no carefully recorded data on long-term outcome of musculo-skeletal function on these doses. Appropriate studies are needed to document such data. With regard to products for factor replacement, economic compulsions lead to the use a variety of factor concentrates and blood-bank products for replacement therapy. Most patients in the developing world do not have access to adequate replacement therapy. Among the rest, some get limited quantities of plasma-derived concentrates while others use cryoprecipitate, fresh frozen plasma or even whole blood. Since the superiority of virus-inactivated purified factor concentrates in achieving the aims of replacement therapy is well established, the aim should be to provide this for all people with haemophilia. This can be achieved by production of such concentrates locally or by importing them. Different models are possible depending on the circumstances in each country.

The use of specific antidotes as a response to bleeding complications during anticoagulant therapy for venous thromboembolism

When a bleeding complication occurs during therapy with heparin or vitamin K antagonists, there is an option to give a specific antidote. Several new anticoagulants have been developed that are likely to have some risk of bleeding complications, for which no specific antidotes are available. Interestingly, it is unknown how often the use of an antidote is necessary in clinical practice. We investigated 1877 patients treated for venous thromboembolism included in three large clinical trials, of which 181 (9.6%) had a total of 225 adjudicated bleeding episodes; 46 hemorrhages being designated as major. Some form of antidote was given to 26 (14.4%) patients with a hemorrhage. Of the patients with at least one major hemorrhage, 19 (41.3%) received an antidote. Vitamin K was given to 23 (1.2%) patients, one (0.05%) patient received protamin sulfate and seven (0.4%) patients received fresh frozen plasma. The use of antidotes was comparable for initial and long-term treatment. Antidotes were statistically significantly more frequently given in Canada as compared to other participating countries. Vitamin K was more frequently given in case of a higher international normalized ratio value. Although antidotes against anticoagulant treatment are widely available, our analysis shows that in only a very small number of patients a direct, or slow-acting antidote to reverse the anticoagulant effect was used.

Effectiveness of alternative treatments for reducing potential viral contaminants from plasma-derived products

An issue of great importance and continuing concern with regard to all products derived from human plasma is their safety from potential contaminants in the source material from which they are purified. Since viral contaminants are a major safety consideration with these products, a number of different methods, including dry heating, vapor heating, filtration and nanofiltration, ultraviolet and gamma irradiation, pasteurization, solvent/detergent (S/D) treatment, sodium thiocyanate treatment, and chromatography (immunoaffinity, metal chelation, affinity, and ion exchange), have been developed to remove or inactivate potentially contaminating viruses. Pasteurization and S/D treatment have emerged as the dominant viral inactivation methods. Results summarized in this review demonstrate that pasteurization is the broadest and most rigorous currently available method for removal of potential viral contaminants from plasma-derived products. S/D treatment requires control over a large number of manufacturing parameters and has no ability to inactivate nonlipid-enveloped viruses. Pasteurization requires control over only a small number of manufacturing variables, is easily monitored, and remains effective even if deviations are encountered from specified protein and stabilizer concentrations and temperature. In addition, pasteurization is effective against a wide range of lipid- and nonlipid-enveloped viruses.

Pharmacokinetic analysis of plasma-derived and recombinant F IX concentrates in previously treated patients with moderate or severe hemophilia B

BACKGROUND

Hemophilia B is an X-linked bleeding disorder that affects approximately 1 in 25,000 males. Therapy for acute bleeding episodes consists of transfusions of plasma-derived (pd-F IX) or recombinant (r-F IX) concentrates.

STUDY DESIGN AND METHODS

A double-blind, two-period crossover study was initiated to assess the pharmacokinetics of pd-F IX and r-F IX and to address patient-specific variables that might influence in vivo recovery. Study product was administered by a single bolus infusion (50 IU/kg) to 43 previously treated patients in the nonbleeding state, and F IX:C levels were measured over a period of 48 hours after infusion.

RESULTS

The mean in vivo recovery in the pd-F IX group was 1.71 +/- 0.73 IU per dL per IU per kg compared with 0.86 +/- 0.31 IU per dL per IU per kg with r-F IX (p <or= 0.0001). There was a significant positive correlation (Pearsons r = 0.62, p <or= 0.0001, 95% CI, 0.37-0.78) between the recoveries of the two products and a weak correlation between the recovery of pd-F IX and baseline F IX:Ag levels. There was no significant difference in the terminal half-lives of the two products.

CONCLUSIONS

The study found wide product- and patient-related variability in recovery. Inherent differences among patients, including baseline F IX, may account for some of the interpatient variability. These differences should be taken into account in optimizing treatment regimens for individual patients with hemophilia B.

Chemical synthesis and spontaneous folding of a multidomain protein: anticoagulant microprotein S

Because of recent high-yield native ligation techniques, chemical synthesis of larger multidomain bioactive proteins is rapidly coming within reach. Here we describe the total chemical synthesis of a designed "microprotein S," comprising the gamma-carboxyglutamic acid-rich module, the thrombin-sensitive module, and the first epidermal growth factor-like module of human plasma protein S (residues 1-116). Synthetic microprotein S expressed anticoagulant cofactor activity for activated protein C in the down-regulation of blood coagulation, and the anticoagulant activity of microprotein S was not neutralized by C4b-binding protein, a natural inhibitor of native protein S in plasma. The correct folding of this complex multidomain protein was enhanced compared with individual modules because the gamma-carboxyglutamic acid-rich module and the thrombin-sensitive module markedly facilitated correct folding of the first epidermal growth factor-like module compared with folding of the first epidermal growth factor-like module alone. These results demonstrate that total chemical synthesis of proteins offers an effective way to generate multidomain biologically active proteins.