Studies on the removal of abnormal prion protein by processes used in the manufacture of human plasma products

Biological Safety of a Highly Purified 10% Liquid Intravenous Immunoglobulin Preparation from Human Plasma

Background

A highly purified 10% liquid intravenous immunoglobulin, IQYMUNE^®, has been developed using an innovative manufacturing process including an affinity chromatography step for the removal of anti-A and anti-B hemagglutinins.

Objectives

The pathogen (viruses and prions) clearance efficacy of the manufacturing process and its robustness for critical steps were investigated.

Methods

The manufacturing process of IQYMUNE^® includes two dedicated complementary virus reduction steps: solvent/detergent (S/D) treatment and 20 nm nanofiltration as well as two contributing steps, namely caprylic acid fractionation and anion-exchange chromatography. The clearance capacity and robustness of these steps were evaluated with a wide range of viruses (enveloped and non-enveloped) and with a model of human transmissible spongiform encephalopathies (TSEs).

Results

The IQYMUNE^® manufacturing process demonstrated a high and robust virus removal capacity with global reduction factors (RFs) of relevant and model viruses: ≥14.8 log₁₀ for human immunodeficiency virus type 1 (HIV-1), ≥16.9 log₁₀ for bovine viral diarrhoea virus (BVDV)/Sindbis virus, ≥15.7 log₁₀ for pseudorabies virus (PRV), ≥12.8 log₁₀ for encephalomyocarditis virus (EMCV) and 11.0 log₁₀ for porcine parvovirus (PPV). The process also exhibited a high removal capacity for the TSE agent with an overall RF of ≥12.9 log₁₀ due to the complementary actions of the caprylic acid fractionation, anion-exchange chromatography and nanofiltration steps.

Conclusion

Data from virus and prion clearance studies fully support the high safety profile of IQYMUNE^®, with a minimal reduction of 11 log₁₀ for the smallest and most resistant non-enveloped virus, PPV, and more than 12 log₁₀ for the TSE agent.

Passive Immunization against Congenital Cytomegalovirus Infection: Current State of Knowledge

Primary infection with the human cytomegalovirus (CMV) occurs in 1-4% of pregnancies. The rates of maternal-fetal CMV transmissions are around 25, 36, 41, and 66%, for infections occurring in the peri-conceptional weeks, first, second, and third trimester of pregnancy, respectively. On the other hand, the severity of fetal organ damage and dysfunction diminishes with increasing gestational age. Congenitally CMV-infected newborns may have neurosensory impairments like mental retardation, cerebral palsy, epilepsy, progressive hearing loss or visual defects, or even may have a fatal outcome. In in-vitro experiments, CMV specific neutralizing IgG antibodies - which are abundant in CMV specific hyperimmune globulin (HIG) products - inhibited the entry of the virus into target cells and hampered viral cell-to-cell spread. This article provides a brief overview on the epidemiology and diagnostic tools in congenital CMV infection. It also concisely summarizes the currently available study results on the safety and effectiveness of HIG treatment. Accordingly, in clinical studies HIG administration to expectant mothers following primary CMV infection (prophylactic use) was shown to lower the risk of maternal-fetal transmission of CMV compared to untreated controls. HIG was also able to ameliorate the disease sequelae in evidently infected fetuses (therapeutic use), as demonstrated by the regression or even resolution of sonographic pathologies including placental inflammation.

Removal of transmissible spongiform encephalopathy prion from large volumes of cell culture media supplemented with fetal bovine serum by using hollow fiber anion-exchange membrane chromatography

Cases of variant Creutzfeldt-Jakob disease in people who had consumed contaminated meat products from cattle with bovine spongiform encephalopathy emphasize the need for measures aimed at preventing the transmission of the pathogenic prion protein (PrPSc) from materials derived from cattle. Highly stringent scrutiny is required for fetal bovine serum (FBS), a growth-medium supplement used in the production of parenteral vaccines and therapeutic recombinant proteins and in the ex vivo expansion of stem cells for transplantation. One such approach is the implementation of manufacturing steps dedicated to removing PrPSc from materials containing FBS. We evaluated the use of the QyuSpeed D (QSD) adsorbent hollow-fiber anion-exchange chromatographic column (Asahi Kasei Medical, Tokyo, Japan) for the removal of PrPSc from cell culture media supplemented with FBS. We first established that QSD filtration had no adverse effect on the chemical composition of various types of culture media supplemented with 10% FBS or the growth and viability characteristics of human embryonic kidney (HEK293) cells, baby hamster kidney (BHK-21) cells, African green monkey kidney (Vero) cells, and Chinese hamster ovary (CHO-k1) cells propagated in the various culture-medium filtrates. We used a 0.6-mL QSD column for removing PrPSc from up to 1000 mL of Dulbecco's modified Eagle's medium containing 10% FBS previously spiked with the 263K strain of hamster-adapted scrapie. The Western blot analysis, validated alongside an infectivity assay, revealed that the level of PrPSc in the initial 200mL flow-through was reduced by 2.5 to > 3 log10, compared with that of the starting material. These results indicate that QSD filtration removes PrPSc from cell culture media containing 10% FBS, and demonstrate the ease with which QSD filtration can be implemented in at industrial-scale to improve the safety of vaccines, therapeutic recombinant proteins, and ex vivo expanded stem cells produced using growth media supplemented with FBS.

Manufacture of immunoglobulin products for patients with primary antibody deficiencies - the effect of processing conditions on product safety and efficacy

Early preparations of immunoglobulin (Ig) manufactured from human plasma by ethanol (Cohn) fractionation were limited in their usefulness for substitution therapy in patients with primary antibody deficiencies (PAD), as Ig aggregates formed during manufacture resulted in severe systemic reactions in patients when given intravenously. Developments in manufacturing technology obviated this problem through the capacity to produce concentrated solutions of intact monomeric Ig, revolutionizing PAD treatment and improving patient life expectancy and quality of life. As the need for Ig has grown, manufacturers have refined further manufacturing technologies to improve yield from plasma and produce therapies, which are easier and less expensive to deliver. This has led to the substitution, partly or wholly, of ethanol precipitation by other techniques such as chromatography, and has also stimulated the production of highly concentrated solutions capable of rapid infusion. Ig products have been associated, since their inception, with certain adverse events, including infectious disease transmission, hemolysis, and thromboembolism. The introduction of standardized manufacturing processes and dedicated pathogen elimination steps has removed the risk of infectious disease, and the focus of attention has shifted to other problems, which appear to have increased over the past 5 years. These include hemolysis and thromboembolism, both the cause for substantial concern and the subject of recent regulatory scrutiny and actions. We review the development of manufacturing technology and the emerging evidence that changes for the optimization of yield and convenience has contributed to the recent incidents in certain adverse events. Industry measures under development will be discussed in terms of their potential to improve safety and optimize care for patients with PAD.

Long-term efficacy and safety of a pasteurized, plasma-derived factor VIII concentrate (Beriate® P) in patients with haemophilia A

Introduction

Beriate^® P was first introduced in Germany in 1990 as factor VIII (FVIII):C^® HS Behring and subsequent product improvements yielded an albumin-free formulation with a specific activity of approximately 170 IU/mg protein. In 1992, the concentration was raised to 100 IU FVIII/mL in the reconstituted product, with a mean specific activity of 270 IU/mg protein. Pathogen safety is achieved by careful donor selection and a combination of pasteurization and chromatographic purification steps.

Materials and methods

We analysed the efficacy and safety of Beriate^® P in the clinical setting from 1996 to 2005 with a focus on surgical patients. Of the 36 patients (mean age: 38 years; range 1–72 years), 29 had severe haemophilia A, two had moderate haemophilia, two had mild haemophilia, and three had sub-clinical haemophilia. Most patients (n = 28) had more than 100 exposure days, representing a total of 202 patient-years with a consumption of 27,811,500 IU of Beriate^® P.

Results

There was no evidence of seroconversion towards relevant viruses, no inhibitor development (35 previously treated patients, one previously untreated patient), no abnormal immunological findings or allergic reactions. In all 36 patients treated for acute bleeding and prophylaxis, and 24 surgeries (15 total joint replacements, eight orthopaedic procedures, one cholecystectomy) in 16 patients with severe haemophilia A, efficacy of Beriate^® P was always rated as “excellent” or “good”, and no thrombosis was reported.

Conclusion

Beriate^® P has an excellent efficacy and safety profile. Many patients who were initiated on Beriate^® P at our centre remain on the treatment today.

Estimating the pathogen safety of manufactured human plasma products: application to fibrin sealants and to thrombin

BACKGROUND

Plasma fractionators have implemented many improvements over the past decade directed toward reducing the likelihood of pathogen transmission by purified blood products, yet little has been published attempting to assess the overall impact of these improvements on the probability of safety of the final product.

STUDY DESIGN AND METHODS

Safety margins for human immunodeficiency virus (HIV), hepatitis C virus (HCV), hepatitis B virus (HBV), hepatitis A virus (HAV), parvovirus B19, and variant form of Creutzfeldt-Jakob disease (vCJD) were calculated for the two fibrin sealants licensed in the United States and for thrombin. These products were selected because their use in a clinical setting is, in most cases, optional, and both were relatively recently approved for marketing by the US Food and Drug Administration (FDA). Moreover, thrombin and fibrinogen both undergo two dedicated virus inactivation steps and/or removal steps in accord with the recommendations of regulatory agencies worldwide. Safety margins were determined by comparing the potential maximum viral loads in contaminated units to viral clearance factors, ultimately leading to the calculation of the residual risk per vial.

RESULTS

The residual risk of pathogen transmission per vial was calculated to be less than 1 in 10(-15) for HIV, HCV, HBV, and HAV for both fibrinogen and thrombin. Owing to the greater quantities that can be present and its greater thermal stability, the calculated risk for parvovirus transmission was 1 in 500,000 vials for fibrinogen and less than 1 in 10(7) per vial for thrombin. Assuming that vCJD is found to be present in plasma donations, its risk of transmission by these purified and processed plasma derivatives would appear to be very low.

CONCLUSIONS

The pathogen safety initiatives implemented by plasma fractionators over the past 10 to 20 years have resulted in products with excellent pathogen safety profiles. Of the agents examined, parvovirus continues to have the lowest calculated margin of safety. Despite this, parvovirus transmissions should be rare. Manufacturers are encouraged to continue exploring processes to further enlarge parvovirus safety margins and to continue exploring ways of eliminating prions.

The variant Creutzfeldt-Jakob Disease: Risk, uncertainty or safety in the use of blood and blood derivatives?

It has been long since French physician Jean-Baptiste Denys carried out the first successful blood transfusion to a human being. Using bird feathers as canules, sheep blood was transfused to a young man. The patient died soon after Denys' treatment and Denys was accused of murder. In the XXI century, known as the biotechnology century, we face new challenges in Medicine. New emerging and reemerging diseases, such as Creutzfeldt-Jakob disease (CJD) or "mad cow disease" and its human variant (vCJD), challenge the biosafety aspects of a widely extended and extremely useful technique, that is, the perfusion of blood, of its derived components and of other pharmacological products obtained from plasma. To face these new challenges we need innovative prevention strategies.

Modern plasma fractionation

Protein products fractionated from human plasma are an essential class of therapeutics used, often as the only available option, in the prevention, management, and treatment of life-threatening conditions resulting from trauma, congenital deficiencies, immunologic disorders, or infections. Modern plasma product production technology remains largely based on the ethanol fractionation process, but much has evolved in the last few years to improve product purity, to enhance the recovery of immunoglobulin G, and to isolate new plasma proteins, such as α1-protease inhibitor, von Willebrand factor, and protein C. Because of the human origin of the starting material and the pooling of 10 000 to 50 000 donations required for industrial processing, the major risk associated to plasma products is the transmission of blood-borne infectious agents. A complete set of measures—and, most particularly, the use of dedicated viral inactivation and removal treatments—has been implemented throughout the production chain of fractionated plasma products over the last 20 years to ensure optimal safety, in particular, and not exclusively, against HIV, hepatitis B virus, and hepatitis C virus. In this review, we summarize the practices of the modern plasma fractionation industry from the collection of the raw plasma material to the industrial manufacture of fractionated products. We describe the quality requirements of plasma for fractionation and the various treatments applied for the inactivation and removal of blood-borne infectious agents and provide examples of methods used for the purification of the various classes of plasma protein therapies. We also highlight aspects of the good manufacturing practices and the regulatory environment that govern the whole chain of production. In a regulated and professional environment, fractionated plasma products manufactured by modern processes are certainly among the lowest-risk therapeutic biological products in use today.

Ensuring the biologic safety of plasma-derived therapeutic proteins: detection, inactivation, and removal of pathogens

Human plasma-derived proteins, such as immunoglobulins, coagulation factors, α₁-antitrypsin, fibrin sealants, and albumin, are widely used as therapeutics for many serious and life-threatening medical conditions. The human origin of these proteins ensures excellent efficacy and compatibility but may also introduce the risk of unintentional disease transmission. Historically, only viruses, particularly hepatitis and HIV, have posed serious threats to the safety of these therapeutics. Fortunately, between 1970 and 1990, the molecular biology of each of the major viruses was elucidated. These advances led to the development and implementation of effective donor screening tests, mainly based on immunoassays and nucleic acid testing, which resulted in a significant reduction of disease transmission risk. In addition, viral inactivation and removal steps were implemented and validated by manufacturers, further reducing the risk associated with known, as well as unidentified, viruses. Since the late 1990s, a different class of transmissible agent, referred to as prions, has been identified as a new risk for disease transmission. However, prion diseases are very rare, and prion transmission through plasma-derived proteins has not been reported to date. The prion-related risk is minimized by deferring donors with certain key risk factors, and by the manufacturing processes that are capable of removing prions. Advances in science and pathogen safety-related technology, compliance with good manufacturing practices by manufacturers, and increasingly stringent regulatory oversight, has meant that plasma-derived proteins have been developed into today’s highly effective therapeutics with very low risk of disease transmission.