Acute Hepatitis C in Haemophiliacs Due to “Virus-Inactivated” Clotting Factor Concentrates

Guidelines on replacement therapy for haemophilia and inherited coagulation disorders in Italy

In the last years, the availability in Italy of technologically advanced products for replacement therapy has produced significant changes in the management of haemophilia and of hereditary bleeding disorders in general. With the aim of a uniform approach to treatment, the Italian Association of Haemophilia Centres express in these guidelines a consensus on therapeutic strategies designed to ensure the highest degree of safety and efficacy for the treatment of inherited coagulopathies. The guidelines provide specific recommendations for the choice of the product according to updated scientific evidence, and advice on optimal dosages for the treatment of rare bleeding disorders. The system for haemophilia care and funding in Italy is briefly described.

Efficacy of viral clearance methods used in the manufacture of activated prothrombin complex concentrates: focus on AUTOPLEX T

Various methods are described for the elimination of infectious viruses from activated prothrombin complex concentrates (aPCCs) and for the analysis of the final products (AUTOPLEX T and FEIBA VH). Viruses of concern in human plasma-derived products are enveloped (hepatitis B and C, cytomegalovirus, Epstein-Barr virus, and human immunodeficiency virus [HIV]) and nonenveloped (hepatitis A and parvovirus B19). Donated blood used for AUTOPLEX T is screened for antihepatitis C, HBsAg, anti-HIV types 1 and 2, and p24 antigen. Plasma pools utilized for raw materials are also tested by PCR for HIV and hepatitis C virus. Partial virus inactivation and partitioning are achieved by purification of the aPCC. Further reduction of virus infectivity is accomplished by lyophilization and dry-heat treatment. Each step undergoes virus elimination validation studies in which a relevant sample is 'spiked' with the appropriate virus or model virus. The total reduction in virus from raw material to final product can then be calculated. For AUTOPLEX T the cumulative log10 reduction factors for several viruses vary from 4.2 to 14.3. This ensures an exceptionally high margin of safety. Definitive evidence for product safety was obtained by clinical observation of treated patients. The viral inactivation process of AUTOPLEX T involves a four-tier viral safety program, including Cohn alcohol fractionation and dry-heat treatment, in place of the two-stage vapour-heating process for FEIBA.

Virus inactivation by solvent/detergent treatment and the manufacture of SD-plasma

Solvent/Detergent (SD) is an extraordinarily effective means for eliminating enveloped viruses from plasma and plasma products. The safety margin suggested by the rapid and complete kill of enveloped viruses observed in the laboratory has been confirmed repeatedly by groups worldwide and by thirteen years of routine clinical use encompassing an estimated 35 million doses of a wide variety of products. Throughout this time, there has not been a single documented case of enveloped virus transmission by an SD-treated product. This record of safety spawned the development of SD-treated plasma as a substitute for fresh frozen plasma (FFP) and has encouraged the adoption of SD for the treatment of non-blood products such as monoclonal antibodies and those derived from recombinant DNA procedures. This review summarizes the use of SD treatment, including its use in combination with other viral elimination procedures, and also summarizes Vitex's initial experience in the manufacture of SD-Plasma, recently licensed by the U.S. FDA.

The choice of plasma-derived clotting factor concentrates

The gloomy picture caused by the AIDS epidemic is now partially lightened by spectacular improvements in therapy. One important step forward toward elimination of the risk of transfusion of blood-borne infections by plasma products was the development of virucidal methods and their application to clotting factor concentrates. Another important advance was the production of ultrapure factor VIII concentrates by immuno-affinity chromatographic techniques. Not only are these concentrates at least as safe as less-pure concentrates in terms of transmission of blood-borne viral infections, but there is also a hint that the deteriorating immune system of HIV-positive haemophiliacs may be stabilized by these highly purified concentrates. Factor VIII produced by recombinant DNA technology is licensed for treatment of haemophilia A. Hopefully, it will be free of the risk of transmitting infections and will be available in sufficiently large amounts to meet the needs of haemophiliacs worldwide. The availability of concentrates containing only factor IX is another substantial step forward in the treatment of haemophilia B, while we wait for the cure of this disease through gene-transfer therapy.

Chronic hepatitis in haemophilia

Chronic hepatitis affects almost all haemophiliacs treated with non-virally inactivated clotting factor concentrates. The virus responsible is hepatitis C (HCV) and most patients have non-neutralising antibodies with circulating virus. Although the majority also have evidence of past infection with hepatitis B, less than 5% are chronic carriers of HBsAg. Chronic hepatitis C can be associated with severe and progressive liver disease but the development of complications is slow. Treatment with recombinant interferon alpha given subcutaneously normalises the liver function in 50% of patients, but 50% of responders relapse on stopping treatment. Liver transplantation is successful in patients with advanced liver disease and it offers the added advantage of phenotypic cure of the haemophilic state.