Hemophilia B Treatment Now Has a Lot of Potential Thanks to Novel Liver-Directed AAV Gene Therapy

Hemophilia B is an X-linked inherited bleeding illness. It results from gene changes that code for the protein coagulation factor IX (F9). These gene changes result in less protein production. A tendency to bleed due to insufficient coagulation factor IX typically affects musculoskeletal tissues. It can also impact other tissues and vital organs. Because the gene that produces the factor IX protein presents on the X chromosome, men are significantly more likely to get the severe type of hemophilia B.

Read Also: Hemophilia Cure: New Gene Therapy Offers Hope to Patients

Hemophilia Inheritance

Hemophilia Inheritance. Image Credit: Domaina, Kashmiri and SUM1

Severe hemophilia B is treated with lifelong prophylaxis with repeated intravenous infusions of factor IX concentrate. Hemophilia B patients currently require regular injections of recombinant Factor IX or replacement therapy weekly. According to a study led by UCL researchers, a single gene therapy injection could significantly lower the bleeding risk experienced by persons with hemophilia B.

Novel gene therapy reduces bleeding risk in Hemophilia B

Gene therapy using the adeno-associated virus (AAV) is a novel strategy for managing hemophilia B. The AAV gene therapy delivers a functional copy of a gene directly to patient tissues to make up for the one functioning poorly. The gene treatment employs a package from the proteins found in the virus’ outer coat. Newly created proteins are present in the blood, and a single infusion can have long-lasting benefits.

In nine out of ten patients who received the new treatment once across four different dose levels, there was increased production of the FIX protein from the liver, negating the need for ongoing weekly medication.

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The 26-week experiment included ten male patients with severe or moderately severe hemophilia B. They will also take part in the long-term follow-up research as well, which will assess the security and durability of FIX expression over 15 years. The drug was usually well tolerated in the trial, however, in one patient who got the highest levels of FIX protein, atypical blood clots developed.

The medicine caused an increase in FIX protein production in nine out of 10 patients, which decreased excessive bleeding. They were also no longer required to receive weekly injections of the FIX protein.

After 26 weeks, FIX protein levels were normal in five patients, increased in three patients with low levels, and were exceptionally high in one patient who had received the maximum dose.

Clinical significance

Current treatment approaches for hemophilia are a regular weekly infusion of recombinant FIX or weekly replacement therapy for a lifetime. This treatment also presents adverse effects such as joint injury and other affectations on the musculoskeletal tissues. This novel study is clinically significant in paving the way for new medications using gene therapy for effective hemophilia B management.

Read Also: Children Treated with Gene Therapy for Adenosine Deaminase Deficiency Still Doing Well a Decade Later


Hemophilia B causes significant blood loss amid other systemic effects on the skeletal system. Patients require a lifelong treatment plan to help their survival. However, this groundbreaking study can significantly change the treatment of Hemophilia B, leading to better patient recovery.


Phase 1–2 Trial of AAVS3 Gene Therapy in Patients with Hemophilia B



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