The choice of plasma-derived clotting factor concentrates

Recent Advances in Gene Therapy for Hemophilia: Projecting the Perspectives

One of the well-known X-linked genetic disorders is hemophilia, which could be hemophilia A as a result of a mutation in the F8 (factor VIII) gene or hemophilia B as a result of a mutation in the F9 (factor IX) gene, leading to insufficient levels of the proteins essential for blood coagulation cascade. In patients with severe hemophilia, factor VIII or factor IX activities in the blood plasma are considerably low, estimated to be less than 1%. This is responsible for spontaneous or post-traumatic bleeding episodes, or both, leading to disease complications and death. Current treatment of hemophilia relies on the prevention of bleeding, which consists of expensive lifelong replacement infusion therapy of blood plasma clotting factors, their recombinant versions, or therapy with recombinant monoclonal antibodies. Recently emerged gene therapy approaches may be a potential game changer that could reshape the therapeutic outcomes of hemophilia A or B using a one-off vector in vivo delivery and aim to achieve long-term endogenous expression of factor VIII or IX. This review examines both traditional approaches to the treatment of hemophilia and modern methods, primarily focusing on gene therapy, to update knowledge in this area. Recent technological advances and gene therapeutics in the pipeline are critically reviewed and summarized. We consider gene therapy to be the most promising method as it may overcome the problems associated with more traditional treatments, such as the need for constant and expensive infusions and the presence of an immune response to the antibody drugs used to treat hemophilia.

New directions to develop therapies for people with hemophilia

INTRODUCTION

The past few decades have seen a tremendous advancement in the management of hemophilia. Whether it is improved methods to attenuate critical viruses, recombinant bioengineering with decreased immunogenicity, extended half-life replacement therapies to mitigate the burden of repeated infusion treatments, novel nonreplacement products to avoid the drawback of inhibitor development with its attractive subcutaneous administration and then the introduction of gene therapy, the management has trodden a long way.

AREAS COVERED

This expert review describes the progress in the treatment of hemophilia over the years. We discuss, in detail, the past and current therapies, their benefits, drawbacks, along with relevant studies leading to approval, efficacy and safety profile, ongoing trials, and future prospects.

EXPERT OPINION

The technological advances in the treatment of hemophilia with convenient modes of administration and innovative modalities offer a chance for a normal existence of the patients living with this disease. However, it is imperative for clinicians to be aware of the potential adverse effects and the need for further studies to establish causality or chance association of these events with novel agents. Thus, it is crucial for clinicians to engage patients and their families in informed decision-making and tailor individual concerns and necessities.

Prevalence of hepatitis C virus infection and human immunodeficiency virus in a cohort of Egyptian hemophiliac children

BACKGROUND AND OBJECTIVE

The risk of blood-borne infections, especially hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infection still remains in developing countries among children receiving blood products as hemophiliacs, but the risk is not known in Egypt. The objective of this study was to detect the prevalence of HCV and HIV infection among hemophiliac children to know the magnitude of the problem and determine potential risk factors.

PATIENTS AND METHODS

This was a cross-sectional study conducted on 100 hemophiliac children that assessed the liver clinically and by laboratory tests. All children were screened for HCV and HIV antibodies by enzyme-linked immunosorbent assay. Those with positive HCV antibody titre were tested by polymerase chain reaction (HCV-PCR).

RESULTS

Forty were positive for HCV antibodies with 19 children (47.5%) HCV-PCR positive as well. The mean age, average frequency of bleeds/year, dose of replacement therapy/year and alanine aminotransferase (ALT) levels were significantly high in HCV-antibody and PCR positive patients as compared to HCV antibody and PCR negative ones. None of our patients had clinical evidence of hepatic involvement or was co-infected with HIV.

CONCLUSION

HIV infection does not appear to be a current health problem in Egyptian hemophiliac children though the prevalence of HCV infection is still high.

The obstetric and gynaecological management of women with inherited bleeding disorders - review with guidelines produced by a taskforce of UK Haemophilia Centre Doctors' Organization

The gynaecological and obstetric management of women with inherited coagulation disorders requires close collaboration between obstetrician/gynaecologists and haematologists. Ideally these women should be managed in a joint disciplinary clinic where expertise and facilities are available to provide comprehensive assessment of the bleeding disorder and a combined plan of management. The haematologist should arrange and interpret laboratory tests and make provision for appropriate replacement therapy. These guidelines have been provided for healthcare professionals for information and guidance and it is also intended that they are readily available for women with bleeding disorders.

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.

Guidelines on the selection and use of therapeutic products to treat haemophilia and other hereditary bleeding disorders

Evidence based guidelines are presented on the selection and use of therapeutic products to treat haemophilia. These guidelines offer advice based on the best published scientific and medical information. They will be reviewed regularly by UKHCDO Advisory Committee. Included are details of therapeutic products available in the UK to treat patients with haemophilia and other bleeding disorders and the background information on which the recommendations are based are presented.

Choice of factor concentrates for haemophilia: a developing world perspective

Provision of factor concentrates continues to be the single greatest challenge in providing effective haemophilia care in the developing world. While concerns for ultimate safety and very high purity dominate the selection of factor concentrates in developed countries, availability and cost are the pressing issues in developing countries. There certainly is concern for reasonable safety but purity is often considered an unaffordable luxury. Cost-effective protocols need to be designed for factor replacement in these countries where liberal on-demand therapy and prophylaxis are not possible. It is also essential to establish a good transfusion service for collecting adequate quantities of safe plasma. Support from government and health insurance is required to allow access to at least modest quantities of virus-inactivated factor concentrates. Depending on the situation in each country, factor concentrates may be imported, contract-fractionated or locally produced. Paradigms of effective management of this problem exist within the developing world. Until such time as these examples are widely emulated, less safe products will continue to be used in situations where a distinction frequent needs to be made between what is ideal and what is practical.

TT Virus Is Present in a High Frequency of Italian Hemophilic Patients Transfused With Plasma-Derived Clotting Factor Concentrates

The prevalence of the blood-borne TT virus (TTV) in Italian hemophiliacs treated with different preparations of factor VIII was determined. Of the 178 hemophilic patients (mean age, 29 years), TTV-DNA was found in 123 (69%), in comparison to 22 of 100 (22%) blood donors (P < .0001). Of the 123 patients who tested positive for TTV, significant numbers were also infected with human hepatitis viruses and/or human immunodeficiency virus (HIV): 31% had TTV and hepatitis C virus (HCV), 22% had TTV, and at least 2 of the 4 known human blood-borne viruses tested, whereas 15% had TTV alone. The risk of acquiring TTV alone was only slightly higher in recipients of unmodified plasma factor concentrates (78%, odds ratio, 1.24; 95% confidence interval [CI], 0.27 to 5.79) than in patients treated with virus inactivated concentrates (67%), whereas the risk was significantly lower in recipients of recombinant factors (11%, odds ratio, 0.09; 95% CI, 0.01 to 0.52). Serum alanine aminotransferase (ALT) levels were elevated in 2 of 27 patients (7%) with TTV alone compared with 43 of 56 patients (77%) coinfected with TTV and HCV and compared with 16 of 21 patients (76%) with HCV alone. Taken together, these results indicate that TTV frequently infects Italian hemophiliacs treated with plasma-derived factor VIII concentrates, both unmodified and virus-inactivated. Our results do not suggest a causal effect of TTV on chronic liver disease in these patients.

TT Virus Is Present in a High Frequency of Italian Hemophilic Patients Transfused With Plasma-Derived Clotting Factor Concentrates

The prevalence of the blood-borne TT virus (TTV) in Italian hemophiliacs treated with different preparations of factor VIII was determined. Of the 178 hemophilic patients (mean age, 29 years), TTV-DNA was found in 123 (69%), in comparison to 22 of 100 (22%) blood donors (P < .0001). Of the 123 patients who tested positive for TTV, significant numbers were also infected with human hepatitis viruses and/or human immunodeficiency virus (HIV): 31% had TTV and hepatitis C virus (HCV), 22% had TTV, and at least 2 of the 4 known human blood-borne viruses tested, whereas 15% had TTV alone. The risk of acquiring TTV alone was only slightly higher in recipients of unmodified plasma factor concentrates (78%, odds ratio, 1.24; 95% confidence interval [CI], 0.27 to 5.79) than in patients treated with virus inactivated concentrates (67%), whereas the risk was significantly lower in recipients of recombinant factors (11%, odds ratio, 0.09; 95% CI, 0.01 to 0.52). Serum alanine aminotransferase (ALT) levels were elevated in 2 of 27 patients (7%) with TTV alone compared with 43 of 56 patients (77%) coinfected with TTV and HCV and compared with 16 of 21 patients (76%) with HCV alone. Taken together, these results indicate that TTV frequently infects Italian hemophiliacs treated with plasma-derived factor VIII concentrates, both unmodified and virus-inactivated. Our results do not suggest a causal effect of TTV on chronic liver disease in these patients.

GB virus C/hepatitis G virus infection in HIV infected patients with haemophilia despite treatment with virus inactivated clotting factor concentrates

AIM

To determine the frequency of GB virus C (GBV-C)/hepatitis G virus (HGV) infection before and after switch to the use of virus inactivated concentrates in haemophiliac patients infected with human immunodeficiency virus (HIV).

PATIENTS AND METHODS

Initial and follow up sera from 49 children with haemophilia were analysed for the presence of GBV-C/HGV RNA and antibodies to HGV (anti-HGV). All patients had been infected with HIV while receiving concentrates without virus inactivation before 1984 and were subsequently treated with virus inactivated concentrates.

RESULTS

In the first available serum sample (1987 or later), two of 49 patients were GBV-C/HGV RNA positive and two further patients were anti-HGV positive. During follow up (mean, 6 years), 14 patients developed markers of GBV-C/HGV infection. Eleven of these had received no blood products except clotting factor concentrates that had been prepared with virus inactivation.

CONCLUSIONS

Despite being treated with virus inactivated clotting factor concentrates, HIV positive patients with haemophilia are at an increased risk of manifesting GBV-C/HGV infection. We hypothesise that GBV-C/HGV is transmitted by these clotting factor concentrates. However, we cannot rule out the emergence of markers of GBV-C/HGV infection as a result of the progression of immune impairment in the course of HIV infection.

High Rates of Hepatitis G Virus Infection in Multitransfused Patients With Hemophilia

The parallel measurement of serum antibodies to the hepatitis G virus (anti-HGV) and of viremia (HGV-RNA) should improve our understanding of HGV transmission by coagulation factor concentrates. The aim of this study was to assess the relationship between HGV, the type of concentrate infused, and liver disease in multitransfused hemophiliacs. To this end, anti-HGV and HGV-RNA were evaluated by an enzyme-linked immunosorbent assay and a nested–polymerase chain reaction assay in patients treated lifelong with nonvirus-inactivated plasma-derived concentrates (n = 128), virus-inactivated concentrates (n = 33), or recombinant factors (n = 7), and in 200 regular blood donors. The prevalence of serum HGV-RNA and anti-HGV was higher in the recipients of nonvirus-inactivated factors than in blood donors (HGV-RNA: 9% v 1.5%, P = .002; anti-HGV: 32% v 5%, P < .0001). In the recipients of virus-inactivated concentrates the prevalences of these markers were similar to those in blood donors (HGV-RNA: 3% v 1.5%; anti-HGV: 15% v 5%). The prevalence of either marker in the recipients of nonvirus-inactivated concentrates was higher than in the recipients of virus-inactivated factors (39% v 18%, P = .04). The former group had serum hepatitis C virus (HCV) RNA or anti-HCV more frequently than the latter group (HCV-RNA: 86% v 15%, P < .0001; anti-HCV: 96% v 18%, P < .0001). Serum alanine aminotransferase was persistently high in 83 (81%) patients with HCV-RNA alone, in 8 (89%) with HCV/HGV coinfection, and in none of the three patients with HGV-RNA only. Thus, HGV infection in hemophiliacs is more common than previous studies of HGV-RNA prevalence have suggested, but it resolved in most cases and caused chronic viremia only in a small number of patients, without biochemical evidence of persistent liver damage.

High Rates of Hepatitis G Virus Infection in Multitransfused Patients With Hemophilia

The parallel measurement of serum antibodies to the hepatitis G virus (anti-HGV) and of viremia (HGV-RNA) should improve our understanding of HGV transmission by coagulation factor concentrates. The aim of this study was to assess the relationship between HGV, the type of concentrate infused, and liver disease in multitransfused hemophiliacs. To this end, anti-HGV and HGV-RNA were evaluated by an enzyme-linked immunosorbent assay and a nested–polymerase chain reaction assay in patients treated lifelong with nonvirus-inactivated plasma-derived concentrates (n = 128), virus-inactivated concentrates (n = 33), or recombinant factors (n = 7), and in 200 regular blood donors. The prevalence of serum HGV-RNA and anti-HGV was higher in the recipients of nonvirus-inactivated factors than in blood donors (HGV-RNA: 9% v 1.5%, P = .002; anti-HGV: 32% v 5%, P &lt; .0001). In the recipients of virus-inactivated concentrates the prevalences of these markers were similar to those in blood donors (HGV-RNA: 3% v 1.5%; anti-HGV: 15% v 5%). The prevalence of either marker in the recipients of nonvirus-inactivated concentrates was higher than in the recipients of virus-inactivated factors (39% v 18%, P = .04). The former group had serum hepatitis C virus (HCV) RNA or anti-HCV more frequently than the latter group (HCV-RNA: 86% v 15%, P &lt; .0001; anti-HCV: 96% v 18%, P &lt; .0001). Serum alanine aminotransferase was persistently high in 83 (81%) patients with HCV-RNA alone, in 8 (89%) with HCV/HGV coinfection, and in none of the three patients with HGV-RNA only. Thus, HGV infection in hemophiliacs is more common than previous studies of HGV-RNA prevalence have suggested, but it resolved in most cases and caused chronic viremia only in a small number of patients, without biochemical evidence of persistent liver damage.