Clinical evaluation of viral safety of coagulation factor VIII and IX concentrates

Immunogenicity of Current and New Therapies for Hemophilia A

Anti-drug antibody (ADA) development is a significant complication in the treatment of several conditions. For decades, the mainstay of hemophilia A treatment was the replacement of deficient coagulation factor VIII (FVIII) to restore hemostasis, control, and prevent bleeding events. Recently, new products have emerged for hemophilia A replacement therapy, including bioengineered FVIII molecules with enhanced pharmacokinetic profiles: the extended half-life (EHL) recombinant FVIII products. However, the main complication resulting from replacement treatment in hemophilia A is the development of anti-FVIII neutralizing alloantibodies, known as inhibitors, affecting approximately 25–30% of severe hemophilia A patients. Therefore, the immunogenicity of each FVIII product and the mechanisms that could help increase the tolerance to these products have become important research topics in hemophilia A. Furthermore, patients with inhibitors continue to require effective treatment for breakthrough bleedings and procedures, despite the availability of non-replacement therapy, such as emicizumab. Herein, we discuss the currently licensed treatments available for hemophilia A and the immunogenicity of new therapies, such as EHL-rFVIII products, compared to other products available.

Recent Advances in the Treatment of Hemophilia: A Review

Progress in hemophilia therapy has been remarkable in the first 20 years of the third millennium, but the innovation began with the description the fractionation of plasma in 1946. The first concentrates followed the discovery of FVIII in the cryoprecipitate of frozen plasma and FIX in the supernatant in the early 1960s, which led to the initial attempts at replacement therapy. Unfortunately, the lack of screening methods for viral pathogens resulted in people with hemophilia (PWH) receiving concentrates contaminated by hepatitis A virus, hepatitis C virus, and human immunodeficiency virus, as these concentrates were made from large industrial pools of plasma derived from thousands of donors. Fortunately, by 1985, viral screening methods and proper virucidal techniques were developed that made concentrates safe. Increasingly pure products followed the introduction of chromatography steps with monoclonal antibodies in the production process. The problem of immunogenicity of exogenously administered concentrates has not yet had a complete solution. The development of alloantibodies against FVIII in about 25-35% of PWH is the most serious adverse effect of replacement therapy. The next major advance followed the cloning of the F8 gene and later the F9 genes, which paved the way to produce concentrates of factors obtained by the recombinant DNA technology. The injected FVIII and FIX molecules had a relatively short circulating half-life in the plasma of people with hemophilia A and B, approximately 12 and 18 hours, respectively. The ability to prolong the plasma half-life and extend the interval between injections followed the application of methods to conjugate the factor molecule with the fragment crystallizable of IgG1 or albumin or by adding polyethylene glycol, which has led to an increase in the half-life of concentrates, especially for rFIX. The next frontier in hemophilia therapy is the application of durable and potentially curative therapies such as with gene addition therapy. Experiments in hemophilia B have demonstrated durable responses. Unfortunately, the results with gene therapy for hemophilia A have not been as remarkable and the durability must still be demonstrated. Nonetheless, the long-term safety, predictability, durability, and efficacy of gene therapy for hemophilia A and B remain an open question. At present, only healthy adult PWH have been enrolled in gene therapy clinical trials. The application of gene therapy to children and those with pre-existing antibodies against the delivery vector must also be studied before this therapy becomes widespread.

Clinical experience with a highly purified factor IX concentrate in patients undergoing surgical operations

The haemostatic efficacy of a new highly purified factor IX concentrate, prepared by metal chelate affinity chromatography, was assessed in 13 patients with haemophilia B undergoing a variety of surgical operations. Four of the patients had developed post-operative thromboembolic complications following previous operations, when treated with a prothrombin complex concentrate. None of the patients in the present series developed any evidence of post-operative thrombotic complications. Effective haemostasis was achieved in all patients, with the exception of a surgical bleed in one case, and late post-operative bleeding in a second patient when the factor IX activity fell below 20iu/dl. The product is treated with a solvent-detergent process that destroys lipid-enveloped viruses, while the affinity chromatography process during manufacture removes in excess of 4 log10 of a non-lipid-enveloped virus. In follow-up studies, none of the patients has shown evidence of fresh infection from the concentrate, when assessed by virological markers. It is concluded that this high-purity concentrate (tradenane 'Replenine') is effective for the treatment of patients with haemophilia B who undergo surgical operations.

New developments in the management of moderate-to-severe hemophilia B

Hemophilia B is an X-linked genetic deficiency of coagulation factor IX (FIX) activity associated with recurrent deep tissue and joint bleeding that may lead to long-term disability. FIX replacement therapy using plasma-derived protein or recombinant protein has significantly reduced bleeding and disability from hemophilia B, particularly when used in a prophylactic fashion. Although modern factor replacement has excellent efficacy and safety, barriers to the broader use of prophylaxis remain, including the need for intravenous (IV) access, frequent dosing, variability in individual pharmacokinetics, and cost. To overcome the requirement for frequent factor dosing, novel forms of recombinant FIX have been developed that possess extended terminal half-lives. Two of these products (FIXFc and rIX-FP) represent fusion proteins with the immunoglobulin G1 (IgG1) Fc domain and albumin, respectively, resulting in proteins that are recycled in vivo by the neonatal Fc receptor. The third product has undergone site-specific PEGylation on the activation peptide of FIX, similarly resulting in a long-lived FIX form. Clinical trials in previously treated hemophilia B patients have demonstrated excellent efficacy and confirmed less-frequent dosing requirements for the extended half-life forms. However, gaps in knowledge remain with regard to the risk of inhibitor formation and allergic reactions in previously untreated patient populations, safety in elderly patients with hemophilia, effects on in vivo FIX distribution, and cost-effectiveness. Additional strategies designed to rebalance hemostasis in hemophilia patients include monoclonal-antibody-mediated inhibition of tissue factor pathway inhibitor activity and siRNA-mediated reduction in antithrombin expression by the liver. Both of these approaches are long acting and potentially involve subcutaneous administration of the drug. In this review, we will discuss the biology of FIX, the evolution of FIX replacement therapy, the emerging FIX products possessing extended half-lives, and novel “rebalancing” approaches to hemophilia therapy.

The ageing patient with haemophilia

Older patients with haemophilia (PWH) face many challenges related not only to haemophilia but also to general comorbidities associated with ageing. This article discusses the clinical experience published about the high prevalence of diseases in older PWH. These conditions are managed in the general population by healthcare workers with little training in haemophilia. Haemophilic arthropathy is common in elderly PWH. Prophylaxis starting at an early age in sufficient dose regimens to prevent arthropathy did not occur in patients who are now older than around 40 yr. Many PWH above this age thus have limitations in their activities of daily life. Cardiovascular diseases have become increasingly common in the growing, ageing cohort of PWH. Lifestyle issues such as sexual dysfunction may be exacerbated by the medical issues and psychological problems associated with haemophilia. Hepatitis C virus is a leading problem in PWH. Coinfection with HIV accelerates the progression to end-stage liver disease. Acute and chronic renal failure is more common in adult PWH than in general population. Other comorbidities are reviewed. The evidence is scarce, so it is imperative to report any experience regarding the diagnosis and treatment of these entities, to improve the quality of life of older PWH.

Pathogen inactivation and removal methods for plasma-derived clotting factor concentrates

Pathogen safety is crucial for plasma-derived clotting factor concentrates used in the treatment of bleeding disorders. Plasma, the starting material for these products, is collected by plasmapheresis (source plasma) or derived from whole blood donations (recovered plasma). The primary measures regarding pathogen safety are selection of healthy donors donating in centers with appropriate epidemiologic data for the main blood-transmissible viruses, screening donations for the absence of relevant infectious blood-borne viruses, and release of plasma pools for further processing only if they are nonreactive for serologic markers and nucleic acids for these viruses. Despite this testing, pathogen inactivation and/or removal during the manufacturing process of plasma-derived clotting factor concentrates is required to ensure prevention of transmission of infectious agents. Historically, hepatitis viruses and human immunodeficiency virus have posed the greatest threat to patients receiving plasma-derived therapy for treatment of hemophilia or von Willebrand disease. Over the past 30 years, dedicated virus inactivation and removal steps have been integrated into factor concentrate production processes, essentially eliminating transmission of these viruses. Manufacturing steps used in the purification of factor concentrates have also proved to be successful in reducing potential prion infectivity. In this review, current techniques for inactivation and removal of pathogens from factor concentrates are discussed. Ideally, production processes should involve a combination of complementary steps for pathogen inactivation and/or removal to ensure product safety. Finally, potential batch-to-batch contamination is avoided by stringent cleaning and sanitization methods as part of the manufacturing process.

Measurement of factor IX activity in plasma-derived and recombinant concentrates: insights from thrombin generation and activation-based assays

BACKGROUND

Hemophilia B, resulting from a deficiency of coagulation factor IX, is treated effectively with either recombinant FIX (r-FIX) or plasma-derived FIX (pd-FIX) concentrates, although differences in pharmacokinetics are observed. FIX is activated in vivo by both activated FXI (FXIa) and tissue factor (TF)-activated FVII (FVIIa); however, conventional activated partial thromboplastin time (APTT)-based assays assess only activation by FXIa.

OBJECTIVES

To examine the differences between pd-FIX and r-FIX concentrates with respect to their thrombogenicity and activation.

METHODS AND RESULTS

FIX ELISA was used to quantify antigenic FIX. Calibrated automated thrombography was performed to evaluate the effect of FIX on thrombin generation. FIXa was quantified by the cleavage of FIXa-specific chromogenic substrate. FIX activation was studied in a purified system.

RESULTS

We found that r-FIX had ~ 1.6-fold greater specific activity than pd-FIX. r-FIX generated a markedly higher thrombin peak than pd-FIX at an equivalent antigen level when coagulation was initiated by TF, but this was not seen in contact activation-triggered thrombin generation (TG). Interestingly, the amount of FIXa in r-FIX concentrate was 10 times higher than that in pd-FIX concentrate. In a purified system, the amount of r-FIXa generated by FXIa in the first 10 min of activation was 1.37-fold that of pd-FIXa, whereas no difference between the concentrates was observed when triggered by TF-FVIIa.

CONCLUSIONS

Clear differences were observed between pd-FIX and r-FIX concentrates, including the proportion of FIXa and the activation by FXIa. These may explain some of the discrepancies observed clinically, and suggest that the APTT may not reflect their resultant in vivo properties.

Analysis of camelid IgG for antivenom development: Immunoreactivity and preclinical neutralisation of venom-induced pathology by IgG subclasses, and the effect of heat treatment

Antivenom is the most effective treatment of snake envenoming and is manufactured from the IgG of venom-immunised horses and sheep. Camelids have a unique IgG structure which may account for the report that camel IgG is less immunogenic and less likely to activate complement than equine or ovine IgG. Camelid IgG therefore offers potential safety advantages over conventional IgGs used for antivenom manufacture. The reported thermostability of camelid IgG also holds promise in the inclusion of a relatively inexpensive anti-microbial heat step in antivenom manufacture. However, these potential benefits of camelid IgG would be much reduced if any one of the three camel IgG subclasses dominated, or under-performed, the serological response of camels to venom immunisation because of the prohibitive manufacturing costs of having to purify, or exclude, one or more IgG subclasses. This study compared the titre, antigen-specificity, relative avidity and ability to neutralise the haemorrhagic and coagulopathic effects of Echis ocellatus venom of each IgG subclass from the venom-immunised camels. The results demonstrated that no one IgG subclass consistently out-performed or under-performed the others in their immunoreactivity to venom proteins and ability to neutralise venom-induced pathologies. We concluded therefore that IgG taken from a pool of immunised camels could be processed into antivenom without requiring the implementation of expensive chromatographic separations to select, or indeed to exclude, a specific IgG subclass. The immunoreactivity of the heavy and light chain, IgG1 subclass, was markedly more vulnerable to extreme heat treatment than the heavy chain-only IgG2 and IgG3 subclasses.

Pharmacokinetics, efficacy and safety of IMMUNATE solvent/detergent (IMMUNATE S/D) in previously treated patients with severe hemophilia A: results of a prospective, multicenter, open-label phase III study

BACKGROUND

IMMUNATE Solvent/Detergent (S/D) is a plasma-derived, human factor VIII (FVIII)/von Willebrand factor (VWF) complex subjected to S/D and vapor heat treatment.

METHODS

This prospective clinical study evaluated the pharmacokinetics (PK) (compared to IMMUNATE), efficacy and safety of IMMUNATE S/D in 56 previously treated patients with severe hemophilia A. Subjects received IMMUNATE S/D either on-demand (47/56), as a prophylactic regimen (49/56), or both (40/56).

RESULTS

IMMUNATE and IMMUNATES/D were equivalent with respect to the FVIII and VWF PK parameters assessed. Bleeding episodes (623) were reported in 47/56 subjects. For 89% of episodes, subjects required only 1 infusion with a mean dose of 29.6 IU/kg and 96% of episodes had an excellent or good response. The duration of prophylaxis ranged from 0.1 to 5.2 months. The median number of bleeds per month in subjects on prophylaxis was 0 (range 0-10). No FVIII inhibitory antibodies were observed in 56 subjects after 2,646 treatment exposure days. No related serious adverse events were reported.

CONCLUSION

The introduction of S/D treatment did not alter the PK characteristics and function of VWF and FVIII molecules in IMMUNATE S/D which is effective and safe for treatment of bleeding episodes, management of surgical procedures and prophylaxis.

A solvent/detergent-treated and 15-nm filtered factor VIII: a new safety standard for plasma-derived coagulation factor concentrates

BACKGROUND

Since the early 1990 s the Committee for Proprietary Medicinal Products has set the mandatory requirement that all manufacturing processes for blood products include two virus removal/inactivation steps that are complementary in their action.

OBJECTIVES

The objective was to develop a manufacturing process for factor VIII (FVIII) including two complementary steps of viral inactivation/elimination.

METHODS

A 35-15 nm nanofiltration step was added to a former FVIII manufacturing process that included solvent/detergent (S/D) treatment to generate a new FVIII concentrate called Factane. The impact of nanofiltration on the structural and functional characteristics of FVIII, as well as virus/transmissible spongiform encephalopathy reduction factors were assessed.

RESULTS

Using an innovative approach, FVIII was successfully nanofiltered at 35-15 nm, while the biological properties of the active substance were unmodified. FVIII coagulant and antigen content for Factane and previous S/D-treated FVIII (FVIII-LFB, commercialized as Facteur VIII-LFB) were comparable. The FVIII one-stage chromogenic and coagulant/antigen ratios confirmed that nanofiltered FVIII was not activated. After nanofiltration, the copurified von Willebrand factor (vWF) was reduced but vWF/FVIII binding properties were unaffected. Phospholipid binding and thrombin proteolysis studies displayed no differences between Factane and FVIII-LFB. The rate of factor Xa generation was slightly lower for Factane when compared to FVIII-LFB. Viral validation studies with different viruses showed no detectable virus in the filtrate.

CONCLUSIONS

Nanofiltration of FVIII at 15 nm is feasible despite the large molecular weight of FVIII and vWF. Nanofiltration has been proven to be highly effective at removing infectious agents while preserving the structural and functional integrity of FVIII.

Therapeutic choices in the current millennium: hemophilia workshop highlights

Many issues affect hemophilia care providers when managing bleeding episodes in individuals with hemophilia. A diverse group of hemophilia providers from the United States met at two workshops to discuss the issues influencing treatment choices in the current millennium and to learn about current advances in treatment of hemophilia. This paper provides a summary of the discussions at these workshops. Despite the progress made in the management of patients with hemophilia, the workshop highlighted the fact that there were still many unanswered questions.

Hepatitis C infection among Dutch haemophilia patients: a nationwide cross-sectional study of prevalence and antiviral treatment

Hepatitis C is a major co-morbidity among patients with haemophilia who received inadequately or non-virus-inactivated clotting factor concentrates before 1992. The objectives of this study were to investigate the prevalence of hepatitis C and the use of antiviral therapies during the last decade among patients with haemophilia in the Netherlands. We performed a cross-sectional study and a questionnaire was sent to all 1519 patients known with haemophilia in the Netherlands between 2001 and 2002. The study population for the present study consisted of 771 patients who had received clotting factor products before 1992 of whom 638 reported their hepatitis C status. In total, 441 of the 638 (68%) patients ever had a positive test for hepatitis C virus (HCV); 344 patients (54%) had a current infection, and 97 (15%) had cleared the virus. Among 344 patients currently HCV infected, 111 (32%) had received treatment for hepatitis C, while 34% (33/97) of patients with an infection in the past had been treated for hepatitis C. In 2002 the prevalence of hepatitis C among patients with haemophilia who received clotting factor products before 1992 was 54%. The majority of patients with a current HCV infection had not been treated with antiviral therapy.

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.

Causality assessment of suspected virus transmission by human plasma products

BACKGROUND

Causality assessment of reports on suspected virus transmission is crucial for early detection of infectious plasma products. Commonly used algorithms, such as the WHO criteria, do not meet the specific requirements for causality assessment of suspected virus transmission.

STUDY DESIGN AND METHODS

A special algorithm, based on nucleic acid amplification and gene sequencing technology, effectiveness of validated virus-inactivation methods, empirical data concerning the safety record of the product, and information on batch-related infection clusters, was developed. The algorithm is focused on laboratory test results or otherwise standardized data, with few clinical data being required. To facilitate practical application, the algorithm has been converted into a graphical decision tree.

RESULTS

The feasibility of the algorithm is shown by causality assessment of sample cases. Three cases are presented with the details of each case used in the 12-question checklist. The answers provided by the checklist led to the causality classification.

CONCLUSION

The algorithm is a tool for evaluating reports of suspected virus transmission in a standardized manner. It thus has the potential to improve early signal detection in pharmacovigilance of plasma products by confirmation or exclusion of suspected infectivity in most cases.

An approach to study the viral safety of plasma-derived products in previously treated, non-infected patients

Using the polymerase chain reaction (PCR), we designed a study concept to evaluate the safety of plasma derivatives in previously treated patients who are non-infected by the specific viruses studied. Several product lots can be studied in a single patient, with a study period for each lot of 3 months. In the present study 19 patients were included for treatment with Baxter Hyland Immuno's PCR-screened factor VIII concentrate Immunate (n=7), factor IX concentrate Immunine (n=10), the by-passing agent FEIBA plus Immunine (n=1), and the protein C concentrate Ceprotin (n=1). PCR testing for hepatitis B, C or HIV genomic material in patient samples was done as well as serological testing. All patients remained negative for the tested markers. All seven Immunate patients completed three treatment periods with three different lots of the study drug. The median study period was 282 days and the median dose 115 000 units, with a median of 115 exposure days. Five of the 10 Immunine patients completed three treatment periods and four patients, two treatment periods. One Immunine patient was discontinued from the study for reasons unrelated to the study drug administration. The median study period was 305 days and the median total dose 82 200 units, with a median of 88 exposure days. Our study presents a new design to approach the evaluation of viral safety of new plasma derivatives in previously treated, non-infected patients (NIPs) and offers several advantages over the currently recommended studies using testing for serological markers of infection in previously untreated patients (PUPs).

Viral safety of B-domain deleted recombinant factor VIII

The possible transmission of blood-borne pathogens has been the impetus behind the development of recombinant products formulated in the absence of human-derived components. The viral safety of Chinese hamster ovary (CHO)-cell-based pharmaceuticals is well established. Over 100 million infusions have been administered without a single known incident of CHO-related viral transmission. The manufacturing process for B-domain deleted recombinant factor VIII (BDDrFVIII) builds on this safety record by using a state-of-the-art multitiered approach to viral safety. This approach includes: (1) extensive testing of the CHO cells used to produce BDDrFVIII; (2) routine viral monitoring of the cell culture production process; (3) a purification process in which a specific viral inactivation procedure has been included; (4) a final formulation that does not incorporate human albumin as the stabilizer; and (5) a thorough validation of the viral inactivation and removal capacity of the purification process. This multifaceted viral safety program offers the hemophilia community a factor VIII product with an exceptional degree of viral safety.

Inactivation of parvovirus B19 in coagulation factor concentrates by UVC radiation: assessment by an in vitro infectivity assay using CFU-E derived from peripheral blood CD34+ cells

BACKGROUND

Nonenveloped and thermostable viruses such as parvovirus B19 (B19) can be transmitted to patients who are receiving plasma-derived coagulation factor concentrates treated by the S/D method for inactivating enveloped viruses. Therefore, it is important to develop and validate new methods for the inactivation of nonenveloped viruses.

STUDY DESIGN AND METHODS

Suspensions of B19 in coagulation factor concentrates (FVIII) were irradiated with UVC light. B19 infectivity was determined by an indirect immunofluorescence assay using CFU-E, as a host cell, derived from peripheral blood CD34+ cells. The effects of catechins on B19 infectivity and on FVIII activity after UVC illumination were also examined.

RESULTS

The indirect immunofluorescence assay estimated the B19 infectivity of samples containing virus copies of 10(5) to 10(11) per 10 microL to be a median tissue culture-infectious dose of 10(0.3) to 10(5.4) per 10 microL. B19 was inactivated by 3 log at 750 J per m(2) of UVC radiation and was undetectable after 1000 or 2000 J per m(2) of irradiation. However, FVIII activity decreased to 55 to 60 percent of pretreatment activity after 2000 J per m(2) of UVC radiation. This was inhibited in the presence of rutin or catechins. Epigallocatechin gallate could maintain FVIII activity at almost 100 percent of pretreatment activity after 2000 J per m(2) of UVC radiation, while B19 infectivity was decreased to undetectable levels, which resulted in >3.9 log inactivation.

CONCLUSION

UVC radiation in the presence of catechins, especially epigallocatechin gallate, appears to be an effective method of increasing the viral safety of FVIII concentrates without the loss of coagulation activity.

The future of plasma-derived clotting factor concentrates

In developed countries, preferred treatments for both haemophilia A and B have moved toward recombinant clotting factor concentrates, while plasma-derived replacement therapies are still required by many patients. Great improvements have been made in producing relatively pathogen-free clotting factor replacements from pooled plasma. The fluidity and complexity of the worldwide plasma product market are discussed in the context of the 'yin and yang' of plasma therapeutics, showing how multiple issues can influence the safety and availability of clotting factor concentrates. Use of plasma-derived products will likely continue for the next decade for patients with inhibitors, patients with von Willebrand disease, those requiring bypassing agents, in immune tolerance induction, and for treatment of rare inherited deficiencies of procoagulant or anticoagulant proteins. Furthermore, in developing countries many of the most advanced therapies are not available for the majority of haemophilia patients, and thus plasma-derived replacement concentrates will continue to be used even for noninhibitor patients.

Pharmacokinetics and acute tolerance of a double virus inactivated plasma derived factor VIII concentrate

To further reduce the risk of possible viral disease transmission, an additional virucidal step was performed in the manufacturing process of a solvent/detergent treated factor VIII concentrate, which consisted of heating the lyophilized preparation at 100 degrees C for 30 min (Emoclot DI; ISI, Italy). Because thermal treatment may modify factor VIII bioavailability, the pharmacokinetic parameters and the acute tolerance of the single viral inactivated concentrate (preparation A) were compared with that of the double viral inactivated one (preparation B). Fifteen patients with severe haemophilia A and positive for HAV Ab were enrolled in a double-blind cross-over study and injected with 32.5 IU kg-1 of preparation A and 27 IU kg-1 of the preparation B. No significant differences between terminal half-life, area under the curve/dose, clearance/kg, volume of distribution at the steady state, in vivo recovery and acute tolerance of the two preparations was observed. The only statistical difference was restricted to Cmax.

Emerging issues in blood safety

Improvements in donor selection, testing of donors for markers of infection, and viral inactivation of plasma-derived products have helped reduce the risk of transfusion-associated infections, including hepatitis B (HBV), hepatitis C (HCV), and human immunodeficiency viruses (HIV). The potential for transmission of emerging infections is illustrated by current concerns about group O strains of HIV, nonenveloped viruses, newly discovered microbial agents, prions, Chagas' disease, tick-borne infections, and the need to assess the frequency of transfusion reactions associated with bacterial contamination.

Characterization of F VIII concentrates produced by two methods incorporating double virus inactivation

The trend toward the production of high purity factor VIII concentrates for clinical use is still in progress. Although all plasma derivatives must undergo viral inactivation procedures, the possibility of transmission of viral diseases is not completely eliminated. In order to reduce such risk, we have included double virus inactivation in the procedure of factor VIII concentrate production. In a scale-up procedure for isolation of factor VIII cryoprecipitate, two methods were used. The first is based on the chromatographic purification of factor VIII after pasteurization of cryoprecipitate solution and solvent/detergent (S/D) inactivation of viruses. The second is based on multistep precipitation of factor VIII by sodium chloride and glycine. Viral inactivation was performed by combination of S/D treatment and heating of final freeze-dried product 30 min at 100 degrees C. The typical yield of factor VIII activity in the freeze-dried product was about 20% for the first method, and 25-30% for the second. Electrophoretic analyses of both factor VIII preparations by SDS-PAGE and IEF show very low content of contaminant proteins, in accordance with observed 400-650-fold increase of their specific activity over plasma. Both factor VIII products were stable in the liquid state for more than 24 h at room temperature. The final products, after double viral inactivation, are considered to be suitable for clinical evaluations.

Treatment of considerations in patients with compartment syndrome and an inherited bleeding disorder

In addition to consultation with an experienced hematologist, the following are recommendations regarding compartment syndrome in a patient with an inherited bleeding disorder. Von Willebrand's Disease. Humate-P (rich in von Willebrand factor) is the replacement therapy of choice for surgical procedures in patients with von Willebrand's disease. In general, in the perioperative period, factor VIII levels between 50% and 100% are ideal with a gradual tapering to maintain levels at 50% for approximately 2 weeks. Adjuncts to therapy are DDAVP and EACA. Hemophilia A. During the initial evaluation and with measurement of compartment pressures, factor VIII replacement to levels in the range of 40% to 60% of normal is appropriate replacement therapy. For fasciotomy, however, factor VIII levels greater than 50% to 100% are required. In patients who have developed antibodies to factor VIII, a number of options are available. With low titers of factor VIII inhibitor, higher doses of factor VIII may be successful in overriding the inhibitor. In patients with higher titers of inhibitor, activated factor VII or porcine factor VIII is recommended. Hemophilia B. Highly purified factor IX replacement aimed at keeping factor levels between 50% and 100% in the perioperative period, followed by maintenance at 50% for approximately 2 weeks, is optimal management. Treatment Algorithm: The Figure outlines an algorithm to aid in the diagnosis and treatment of compartment syndrome in the patient with an inherited bleeding disorder. In a suspected case of compartment syndrome due to a soft-tissue hemorrhage or injury, factor replacement as outlined above should be initiated. Unequivocal clinical findings in the normal patient usually would be an indication to proceed to fasciotomy without obtaining compartment pressures. In the patient with an inherited bleeding disorder, however, factor replacement and subsequent normalization of the clotting cascade may help lowe compartment pressures. Therefore, we advocate obtaining initial pressures even with clinical findings of an acute compartment syndrome. At our institution, we advocate using an automated handheld pressure monitor (Stryker, Ontario, Canada) or the needle injection technique as described by Whitesides et al. In interpreting the obtained pressures, we choose to use the guidelines as described by Heppenstall et al. Briefly, Heppenstall et al determined that the pressure threshold at which cellular damage occurred was related more closely to the difference between the mean arterial blood pressure and compartment pressure than with the absolute compartment pressure alone; this measurement is called delta P. If delta P is > 30 mm Hg, then one should continue factor replacements and perform serial clinical and pressure examinations. Pressures should be taken every hour for 2 hours total. If the patient worsens in either respect, then the physician should enter the other limb of the algorithm for delta P < 30 mm Hg. For the patient with a delta P < 30 mm Hg, the amount of time since onset of symptoms must be considered. Since the patient may improve with adequate factor replacement, a delta P < 30 mm Hg mercury does not dictate automatic fasciotomy. An adequate time trial of replacement therapy may be attempted. In patients whose pressures do not begin normalizing, we advocate proceeding to fasciotomy. Patients who begin to normalize pressures during a 2-hour trial can be followed with serial clinical and pressure examinations. Any worsening in either scenario is an indication for fasciotomy; otherwise, observation and factor replacement may be continued. After initial decompression, staples may be placed in both wound edges with an elastic vascular loop woven between the two edges in a "shoelace" pattern. Then while waiting for closure, the loops can be gradually tightened at the bedside. Definitive closure should be attempted around the fifth postoperative day. All closure techniques should be pre

Prophylactic therapy for hemophilia in a developing country, Turkey

Prophylaxis has been practiced for many years in Europe and is gaining acceptance worldwide with current viral inactivation procedures. Unfortunately, the high cost of prophylaxis is currently the major obstacle to its implementation in developing countries such as Turkey. The aim of this controlled preliminary study is to evaluate the efficacy, safety, and feasibility of prophylaxis. Seven boys aged 1.5-7 years (5.0 +/- 1.8), who had severe hemophilia (six A, one B) received 20-50 IU/kg factor twice weekly and were followed up for 6-24 months (14.5 +/- 6.6). Intermediate concentrates have been used in hemophilia A and ultrapure product for hemophilia B. The data obtained for the same group of patients before prophylaxis were used as a control group. Another control group was selected in another group of 10 hemophiliacs, mean age 12.5, and received treatment on demand. During prophylactic treatment, the episodes of bleeding were decreased (from 10.5 +/- 3.2 to 4.5 +/- 3.6). Orthopedic and radiologic joint scores were stable (from 0 to 1 and from 1.1 +/- 1.2 to 1.0 +/- 1.5). The patients spent significantly fewer days in the hospital (from 18 +/- 12 to 0.7 +/- 0.6). None of the patients was infected with hepatitis A, hepatitis B, or human immunodeficiency virus. One patient was seroconverted with anti-hepatitis C virus in the third month of prophylaxis. Mean consumption of concentrates for prophylaxis was 3489 +/- 960 IU/kg per year compared with 2073 +/- 1302 in conventional therapy. Prophylaxis was superior to treatment on demand even when given in a twice-weekly period with intermediate concentrates. In Third World countries, prophylaxis should be tried at least in selected severely hemophilic children in order to prevent disabilities.

Viral safety of a new highly purified factor VIII (OCTATE)

The inactivation of both transfusion-relevant and model viruses by modified pasteurisation (10 hours at 63 degrees C in solution) has been evaluated following the established guidelines of the EU CPMP Ad Hoc Working Party on Biotechnology/Pharmacy. This heat treatment was introduced into the manufacturing process of OCTAVI, a very high purity factor VIII concentrate stabilized only by von Willebrand factor, in the presence of a proprietary mixture of low molecular weight stabilizers. Both enveloped (human immunodeficiency virus, Sindbis virus, herpes simplex virus, pseudorabies virus) and nonenveloped viruses (poliovirus, Coxsackievirus, hepatitis A virus) were inactivated by this heating step by more than 4.7 log10. The combination of the solvent/detergent step used in the manufacture of OCTAVI with this modified pasteurization leads to a double virus-inactivated factor VIII concentrate (OCTATE) with a viral safety distinctly superior to monoinactivated products.

Reduction in transmission of hepatitis C after the introduction of a heat-treatment step in the production of C1-inhibitor concentrate

BACKGROUND

The transmission of viral infections via protein concentrates made from a large pool of plasma depends on the selection of donors, fractionation process, and virucidal methods. To date, no data are available on the infectivity risk of plasma concentrates of the inhibitor of the first component of complement (C1-INH).

STUDY DESIGN AND METHODS

The prevalence of blood-borne viral infections and levels of transaminases were evaluated in patients treated with a large-pool plasma concentrate of the inhibitor of C1-INH before and after the introduction of virucidal methods. The study included 85 patients with hereditary angioedema and 4 with acquired angioedema. The patients were divided into three groups: 1) 48 untreated patients; 2) 22 patients treated with non-virus-inactivated C1-INH concentrates; and 3) 19 patients treated with virus-inactivated concentrates. Serum samples obtained at various times after the infusion of concentrate were assayed for alanine amino-transferase and tested for hepatitis B surface antigen and antibodies to hepatitis C virus (anti-HCV) and human immunodeficiency virus (anti-HIV); anti-HCV-negative subjects exposed to the concentrate were also tested for HCV RNA.

RESULTS

Prevalences of HCV infection and elevated alanine aminotransferase are significantly lower in patients treated with virus-inactivated concentrates than in those exposed to non-virus-inactivated concentrates. No patients were anti-HIV positive.

CONCLUSION

This study suggests that C1-INH concentrates transmitted HCV, but that the virucidal methods adopted are effective in reducing the infectivity.

Low risk of viral infection after administration of vapor-heated factor VII concentrate or factor IX complex in first-time recipients of blood components. International Factor Safety Study Group

BACKGROUND

Vapor-heated human factor VII concentrate and human factor IX complex are both obtained from prothrombin complex, undergo similar methods of manufacture, and are subjected to an identical two-step vapor-heating process for virus inactivation.

STUDY DESIGN AND METHODS

Intermediate-purity vapor-heated human factor VII concentrate and vapor-heated human factor IX complex were monitored for safety with regard to viral infection in the context of an International Factor Safety Study, a prospective study that follows the revised recommendations from the International Congress of Thrombosis and Hemostasis (ICTH). Because the rarity of the respective hereditary deficiencies would have made separate analyses unrealizable, the results were combined for the final analysis. Entry required that patients have no history of transfusion with any blood derivative. After the first infusion of the study drug, patients were monitored for 6 months for the development of non-A, non-B hepatitis (NANBH) and infection with hepatitis B virus (HBV) and for 15 months for infection with hepatitis C virus (HCV) and human immunodeficiency virus (HIV). An event was defined as a positive result on any test for any infection. An alanine aminotransferase level more than 2.5 times the upper limit of normal on two consecutive occasions was defined as an event for NANBH. HBV infection was monitored with tests for three different HBV markers: the HBV surface antigen, antibody against the HBV surface antigen, and antibody against HBV core antigen. HCV and HIV infection were monitored with tests for HCV and HIV antibodies.

RESULTS

The 25 patients who completed the study (1 has not completed the study and 1 dropped out) received a total of 434 infusions comprising 17 different production lots of the concentrates. Twenty patients were analyzable for NANBH and 25 for HCV and HIV infection. Since most patients had been given HBV vaccination, only 4 patients were analyzable for this end point. None of the patients showed evidence of having developed an event. These data satisfy ICTH criteria when the products are considered together, but vapor-heated factor VII concentrate does not qualify alone because there were only five patients in this group.

CONCLUSION

Vapor-heated factor VII concentrate and vapor-heated factor IX complex are associated with a low risk of viral infection. Preliminary results are also presented, indicating that the concentrates are safe with regard to inhibitor development.

A cross-over pharmacokinetic and thrombogenicity study of a prothrombin complex concentrate and a purified factor IX concentrate

A prospective cross-over study was carried out on 19 patients with haemophilia B. comparing the pharmacokinetics of a purified factor IX concentrate prepared by metal chelate affinity chromatography (9MC) with a conventional three-factor prothrombin complex concentrate (9A). The highly purified factor IX concentrate was shown to have a half-life comparable to the PCC; the in vivo recovery of the purified concentrate was significantly greater than that of the complex (P < 0.01). The 20% change in the value of the International Standard for Factor IX Concentrate, introduced in 1988, might have been expected to lower the recovery values. However, the in vivo recovery for both concentrates was somewhat higher than reported previously, particularly in the older literature. In nine patients, serial assays for fibrinopeptide A, prothrombin fragment F1+2 and thrombin-antithrombin complexes (TAT) were performed to assess the potential thrombogenicity of the two concentrates. Evidence was obtained that there was significantly less activation of coagulation following administration of purified factor IX (9MC), as compared to the activation that occurred after the PCC.

Prevalence of infection with the hepatitis C virus among Italian hemophiliacs before and after the introduction of virally inactivated clotting factor concentrates: a retrospective evaluation

In July 1985, all coagulation factor concentrates were withdrawn from the market in Italy and replaced with virally inactivated concentrates. A retrospective survey comparing the prevalence of the antibody to the hepatitis C virus (anti-HCV) in hemophiliacs multitransfused with nonvirally inactivated concentrates until 1985 with that in previously untreated hemophiliacs transfused exclusively with virally inactivated concentrates since 1985 has been conducted in 9 Italian hemophilia centers. The centers, which follow about one-fourth of all the Italian hemophiliacs, provided information about 708 patients infused for the first time before 1985 (group A) and 80 patients infused for the first time between 1985 and 1991 (group B). The prevalence of anti-HCV was 83% (591/708) in group A and 6% (5/80) in group B. For the 5 anti-HCV-seropositive patients from group B, dry heating, hydrophobic interaction chromatography plus dry heating (2 patients), hot vapor and pasteurization were the virucidal methods used for the concentrates implicated in HCV transmission. In the case associated with pasteurization, there is the possibility of intrafamilial transmission of HCV. It appears from this retrospective analysis that there has been a substantial reduction in the risk of HCV transmission since the adoption of virucidal methods. However, these methods do not eliminate completely the risk, which might be further reduced by the recent adoption of anti-HCV screening for plasma donations used to manufacture concentrates.