FIX-GT: Factor IX Gene Therapy Study for Patients with Hemophilia B

Brief Summary

This study will evaluate the safety of a new gene therapy (FLT180a) in adult males with hemophilia B.

Standard hemophilia B treatment involves intravenous infusions of plasma-derived or recombinant factor concentrates at the time of a bleed or as regular prophylactic infusion of factor concentrate. This approach is effective at arresting hemorrhage but cannot prevent chronic damage that ensues after a bleed. The relatively short half-life of standard FIX necessitates intravenous administration of factor concentrates two to three times a week for prophylaxis against hemorrhage, which is invasive, inconvenient, costly and problematic for children.

Our prior research suggests continuous synthesis of FIX by the host cells after a single administration of gene therapy may help prevent bleeding episodes and eliminate the need for regular infusions. These findings also suggest gene therapy may offer the potential for a functional cure in some patients.  

Primary Objective

• To assess the safety of FLT180a in adults with hemophilia B at up to three different dose levels

Eligibility Criteria

Inclusion criteria include:

• Male
• At least 18 years old
• Diagnosis of hemophilia B:
  • Documented severe FIX deficiency with plasma FIX activity of < 1% of normal, OR
  • Moderately severe FIX deficiency with plasma FIX activity level between ≥ 1% and ≤ 2% and a severe bleeding phenotype
• Lack of neutralizing anti-AAV-S3 antibodies using an in vivo transduction inhibition assay within 4 weeks of vector administration

Exclusion Criteria include:

• Presence of neutralizing anti-human FIX antibodies at time of enrollment or previous history of FIX inhibitor
• High risk of thromboembolic event
• Use of investigational therapy for hemophilia within 30 days before enrollment
• Active hepatitis B or C and HBsAg or HCV RNA viral load positivity, respectively, or currently on antiviral therapy for hepatitis B or C
• Prior treatment with any gene transfer medicinal product

Study Sites

St. Jude Children’s Research Hospital
Memphis, Tennessee

Collaborating sites in and outside the U.S.

About this study

Hemophilia B is an inherited bleeding disorder caused by a defect in the F9 gene. If you have hemophilia B, your liver doesn’t make enough factor IX protein. Factor IX helps your blood clot properly.  It is sometimes known as clotting factor.

Usually, hemophilia B treatment involves frequent doses of factor IX protein, given through your veins. In this clinical trial, we will test a new experimental treatment. We will take a healthy F9 gene and send it to your liver so you can make your own factor IX protein. The healthy gene will be carried by a vector. A vector is a virus that has been disabled so it can no longer cause an infection. This type of intervention is called gene therapy.

FLT180a is the name of the vector used in this study. It is not approved by the U.S. Food and Drug Administration (FDA).

If you qualify for the study, you will come to St. Jude and be given a one-time dose of FLT180a through your veins. You will need to come back to St. Jude or another participating Hemophilia Treatment Center for follow-up visits for six months after receiving the drug.

Purpose of this clinical trial

The main goal of this study is to test the safety of FLT180a at different doses and to find out what effect it has on patients. This is the first time this drug has been used in humans.

Eligibility overview

• Male
• At least 18 years old
• Diagnosis of hemophilia B