A Brighter Future For Hemophilia B Patients With Advances In Gene Therapy
Hemophilia B is a rare genetic disorder that causes bleeding problems due to a deficiency or abnormality of clotting factor IX. This occurs due to a mutation in the F9 gene. People with hemophilia B may experience easy bruising, nosebleeds, bleeding into joints and muscles, and bleeding after surgery or dental procedures12. Hemophilia B is inherited in an X-linked recessive manner, which means it mostly affects males who inherit a faulty gene from their mothers. While conventional treatments can be life-saving for hemophilia B patients, the disease still reduces quality of life dramatically. Recent advances in gene therapy, including experimental approaches, show great promise and could potentially transform the outlook for people with hemophilia B in the near future.
Limitations Of Conventional Hemophilia B Treatment
The main treatment for hemophilia B is to replace the missing clotting factor IX through intravenous infusion. This can be done to stop a bleeding episode or to prevent bleeding episodes from happening. The replacement factor can be derived from human blood or made in a laboratory. Other treatments include the use of hormonal medications to stimulate production of more clotting factor, drugs to prevent bleeding, clot-preserving medications, fibrin sealants that are applied to wounds, physical therapy to preserve or improve joint mobility in case of damage to the joints from internal bleeding. The limitations of these treatments for hemophilia B include:
- The risk of developing inhibitors, which are antibodies that attack the replacement factor and make it less effective.
- The cost and availability of treatment products, especially in low-resource settings.
- The need for regular infusions and monitoring of factor levels and bleeding symptoms.
- The potential side effects of treatment products, such as allergic reactions, infections, liver damage, or blood clots.
Gene Therapy For Hemophilia B
Gene therapy for hemophilia B is a new treatment strategy that aims to correct the faulty gene responsible for defects or deficiency of clotting factor IX1. The idea is to deliver a working gene for factor IX to the liver cells, where it can produce the clotting protein and increase the blood levels of factor IX.
One type of gene therapy for hemophilia B uses a modified virus called adeno-associated virus 5 (AAV5) as a vector to carry the gene for factor IX12. The gene is modified to produce a variant of factor IX called Padua, which has higher clotting activity than normal factor IX2. This type of gene therapy is given as a one-time infusion through a vein12.
The first gene therapy product for hemophilia B that uses this approach just received approval from the US FDA last year. The drug has been shown to reduce the annualized bleeding rate, increase the factor IX activity levels, and decrease the need for factor IX replacement therapy in adults with hemophilia B. Gene therapy is also beneficial for ocular diseases. Learn more about gene therapy for ocular diseases here.
The most obvious benefits of gene therapy for hemophilia B include:
- Providing a long-lasting or even permanent solution for hemophilia B.
- Improving the quality of life and reducing the burden of disease for people with hemophilia B.
- Reducing the cost and availability issues of factor IX replacement products.
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