Nanofiltration as a robust method contributing to viral safety of plasma-derived therapeutics: 20 years' experience of the plasma protein manufacturers.

BACKGROUND: Nanofiltration entails the filtering of protein solutions through membranes with pores of nanometric sizes that have the capability to effectively retain a wide range of viruses. STUDY DESIGN AND METHODS: Data were collected from 754 virus validation studies (individual data points) by Plasma Protein Therapeutics Association member companies and analyzed for the capacity of a range of nanofilters to remove viruses with different physicochemical properties and sizes. Different plasma product intermediates were spiked with viruses and filtered through nanofilters with different pore sizes using either tangential or dead-end mode under constant pressure or constant flow. Filtration was performed according to validated scaled-down laboratory conditions reflecting manufacturing processes. Effectiveness of viral removal was assessed using cell culture infectivity assays or polymerase chain reaction (PCR). RESULTS: The nanofiltration process demonstrated a high efficacy and robustness for virus removal. The main factors affecting nanofiltration efficacy are nanofilter pore size and virus size. The capacity of nanofilters to remove smaller, nonenveloped viruses was dependent on filter pore size and whether the nanofiltration process was integrated and designed with the intention to provide effective parvovirus retention. Volume filtered, operating pressure, and total protein concentration did not have a significant impact on the effectiveness of virus removal capacity within the investigated ranges. CONCLUSIONS: The largest and most diverse nanofiltration data collection to date substantiates the effectiveness and robustness of nanofiltration in virus removal under manufacturing conditions of different plasma-derived proteins. Nanofiltration can enhance product safety by providing very high removal capacity of viruses including small non-enveloped viruses.

Virus Filtration and Flow Variation: An Approach To Evaluate Any Potential Impact on Virus Retention.

Virus removal by filtration has been an important improvement for the safety margins of plasma-derived medicinal products and has become a standard manufacturing process step for recombinant proteins. While the mechanism of action was initially considered to be strictly size-based, it has recently been recognized that a more complex interaction of the specific filter membrane and its pore architecture with filtrate flow rates may potentially influence the level of virus removal. Based on this improved understanding, parameters beyond the traditional state-of-the-art may need to be included into the design and control of these processes, and the validity of virus removal data generated in small-scale models for the manufacturing scale processes may need to be reevaluated. This article presents a tool for the analysis of flow rate during manufacturing or virus-spiked small-scale runs with a focus on the effects of low or no flow (stop) situations on the robustness of virus removal. LAY ABSTRACT: Virus removal by filtration has improved safety margins of plasma-derived medicinal products and recombinant proteins. However, low or no flow (stop) situations during virus filtration may potentially affect virus removal. Transforming filtrate flow versus time data into histograms generates intuitively understandable visuals that provide a powerful tool to investigate the equivalence of manufacturing scale processes and down-scaled virus-spiked study runs, and thus to understand the robustness of virus removal for this parameter. With this tool at hand, lower mean flow rates during small-scale experiments are an elegant approach to support the robustness of virus filtration with respect to this parameter at manufacturing scale.

The evolution of down-scale virus filtration equipment for virus clearance studies.

The role of virus filtration in assuring the safety of biopharmaceutical products has gained importance in recent years. This is due to the fundamental advantages of virus filtration, which conceptually can remove all pathogens as long as their size is larger than the biomolecule of commercial interest, while at the same time being neutral to the biological activity of biopharmaceutical compound(s). Major progress has been made in the development of adequate filtration membranes that can remove even smaller viruses, or possibly even all. Establishing down-scaled models for virus clearance studies that are fully equivalent with respect to operating parameters at manufacturing scale is a continuing challenge. This is especially true for virus filtration procedures where virus clearance studies at small-scale determine the operating parameters, which can be used at manufacturing scale. This has limited volume-to-filter-area-ratios, with significant impact on process economics. An advanced small-scale model of virus filtration, which allows the investigation of the full complexity of these processes, is described here. It includes the automated monitoring and control of all process parameters, as well as an electronic data acquisition system, which is fully compliant with current regulatory requirements for electronic records in a pharmaceutical environment.

Robustness of solvent/detergent treatment of plasma derivatives: a data collection from Plasma Protein Therapeutics Association member companies.

BACKGROUND: Solvent/detergent (S/D) treatment is an established virus inactivation technology that has been applied in the manufacture of medicinal products derived from human plasma for more than 20 years. Data on the inactivation of enveloped viruses by S/D treatment collected from seven Plasma Protein Therapeutics Association member companies demonstrate the robustness, reliability, and efficacy of this virus inactivation method. STUDY DESIGN AND METHODS: The results from 308 studies reflecting production conditions as well as technical variables significantly beyond the product release specification were evaluated for virus inactivation, comprising different combinations of solvent and detergent (tri(n-butyl) phosphate [TNBP]/Tween 80, TNBP/Triton X-100, TNBP/Na-cholate) and different products (Factor [F]VIII, F IX, and intravenous and intramuscular immunoglobulins). RESULTS: Neither product class, process temperature, protein concentration, nor pH value has a significant impact on virus inactivation. A variable that did appear to be critical was the concentration of solvent and detergent. CONCLUSION: The data presented here demonstrate the robustness of virus inactivation by S/D treatment for a broad spectrum of enveloped test viruses and process variables. Our data substantiate the fact that no transmission of viruses such as human immunodeficiency virus, hepatitis B virus, hepatitis C virus, or of other enveloped viruses was reported for licensed plasma derivatives since the introduction of S/D treatment.

Virus inactivation during the freeze-drying processes as used for the manufacture of plasma-derived medicinal products.

BACKGROUND: Freeze-drying is a technology widely used during the production of plasma-derived medicinal products. Several studies have shown that freeze-drying can also result in virus inactivation and particularly of hepatitis A virus (HAV). To date, however, the variables critical for virus inactivation during freeze-drying have not been investigated systematically. STUDY DESIGN AND METHODS: Five different lyophilization processes covering the range used for different plasma-derived medicinal products (Factor [F]VII, FVIII, F IX, FVIII inhibitor bypassing activity, and fibrin sealer protein [FSP]) were investigated for their potential to inactivate HAV as well as bovine viral diarrhea virus (BVDV) and pseudorabies virus (PRV). RESULTS: Our investigation demonstrates that freeze-drying results in significant inactivation of HAV, with reduction factors between 2.5 and 5.9 log [TCID(50)]. Also, BVDV and PRV were inactivated, although to a lesser extent. While the specific details of the freeze-drying processes investigated only had a minor influence on virus inactivation, the different compositions of product intermediates had a rather pronounced impact. CONCLUSION: Lyophilization contributes to the safety of plasma derivatives, in particular with the inactivation of HAV. The extent of HAV inactivation is strongly influenced by the respective product matrix rather than the design of the lyophilization cycle, which will require a case-to-case assessment for each product intermediate.

Inactivation of parvovirus B19 during STIM-4 vapor heat treatment of three coagulation factor concentrates.

BACKGROUND: To enhance the viral safety margins, nanofiltration has been widely integrated into the manufacturing process of plasma-derived medicinal products. Removal of smaller agents such as parvovirus B19 (B19V) by filtration, however, is typically less efficient. Because recent investigations have demonstrated that B19V may be more heat sensitive than animal parvoviruses, the potential B19V inactivation by a proprietary vapor heating procedure (STIM-4) as incorporated into the manufacturing processes of several nanofiltered coagulation factor concentrates was investigated. STUDY DESIGN AND METHODS: An infectivity assay based on quantitative reverse transcription-polymerase chain reaction (TaqMan, Applied Biosystems) detection of B19V mRNA after inoculation of a permissive cell line (UT7 Epo S1 cells) was used to investigate the virus inactivation capacity of the STIM-4 vapor heat treatment as used during the manufacture of nanofiltered second-generation Factor VIII inhibitor-bypassing activity (FEIBA), F IX complex, and FVII products. RESULTS: In contrast to animal parvoviruses, both B19V genotypes investigated, that is, 1 and 2, were shown to be surprisingly effectively inactivated by the STIM-4 vapor heat treatment process, with mean log reduction factors of 3.5 to 4.8, irrespective of the product intermediate tested. CONCLUSION: The newly demonstrated effective inactivation of B19V by vapor heating, in contrast to the earlier used animal parvoviruses, results in significant B19V safety margins for STIM-4-treated coagulation factor concentrates.