Study on the Safety and Effectiveness of Etranacogene Dezaparvovec Gene Therapy for Adults with Severe or Moderately Severe Hemophilia B and AAV5 Antibodies

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What is this study about?

This clinical trial is focused on studying a condition called Hemophilia B, which is a genetic disorder that affects the blood’s ability to clot properly. People with this condition often experience excessive bleeding because they have low levels of a protein called Factor IX, which is essential for blood clotting. The study is testing a new treatment called CSL222 (Etranacogene Dezaparvovec), which is a type of gene therapy. This treatment uses a harmless virus to deliver a healthy version of the Factor IX gene to the liver, where it can help produce the necessary protein to improve blood clotting.

The purpose of the study is to evaluate the effectiveness and safety of this gene therapy in adults with severe or moderately severe Hemophilia B who have specific antibodies, known as AAV5 neutralizing antibodies, before treatment. Participants will receive a single dose of the gene therapy through an intravenous infusion, which means it will be delivered directly into the bloodstream. The study will monitor participants over a period of time to see how well the treatment works in reducing bleeding episodes compared to their previous standard care, which involved regular Factor IX replacement therapy.

Throughout the study, researchers will keep track of various health indicators, including the number of bleeding episodes, any side effects, and changes in liver function. The study aims to provide valuable information on whether this gene therapy can offer a more effective and convenient treatment option for people living with Hemophilia B. Participants will be closely monitored by healthcare professionals to ensure their safety and well-being during the trial.

1 lead-in period

During this period, maintain your current routine of Factor IX (FIX) prophylaxis. This phase lasts for at least 6 months.

You will be required to complete an electronic diary (eDiary) to track your health status and any bleeding episodes.

2 screening and eligibility confirmation

Eligibility is confirmed through specific criteria, including age, hemophilia B diagnosis, and previous exposure to FIX therapy.

Two consecutive detectable AAV5 neutralizing antibody (NAb) titer results are required between screening and the final lead-in visit.

3 treatment administration

Receive a single dose of CSL222 (etranacogene dezaparvovec) gene therapy through an intravenous infusion.

This treatment is designed to potentially reduce the need for continuous FIX prophylaxis.

4 post-treatment monitoring

Regular monitoring will occur to assess the treatment’s efficacy and safety.

This includes tracking the annualized bleeding rate (ABR) and any treatment-emergent adverse events (TEAEs).

5 long-term follow-up

Follow-up will continue for up to 18 months post-treatment to evaluate stable FIX expression and overall health outcomes.

Assessments will include liver ultrasounds, blood tests, and monitoring for any new or resolved joint issues.

Who Can Join the Study?

Must be at least 18 years old and considered legally an adult according to the laws of the country.
Must have been born with Hemophilia B, a condition where the blood doesn’t clot properly, with a known severe or moderately severe deficiency of a protein called FIX (Factor IX), which is 2% or less of the normal level in the blood. The person should be on regular FIX treatment to prevent bleeding.
Must have two consecutive positive results for a specific test called AAV5 NAb titer between the initial screening and a later visit. This test measures the presence of certain antibodies in the blood.
Must have had more than 150 days of previous treatment with FIX replacement therapy.
Must have been on a stable FIX treatment plan for at least 2 months before the initial screening.
Must be able to independently and accurately fill out an electronic diary during the initial period of the study, as determined by the study doctor.
Must agree to use barrier contraception, like condoms, for 1 year starting from the day of receiving the study treatment called CSL222.
Must be able to give informed consent after receiving verbal and written information about the study.
The study doctor must believe that the participant, or their legally acceptable representative, understands the nature, scope, and possible consequences of the study and can follow the study procedures.

Who Cannot Join the Study?

Individuals who do not have Hemophilia B cannot participate. Hemophilia B is a condition where the blood does not clot properly due to a lack of a specific protein called Factor IX.
Participants must be within the specified age range for the study.
Both males and females are eligible, but certain conditions may exclude individuals.
Individuals who are part of a vulnerable population may not be eligible. A vulnerable population includes groups who may have limited ability to give informed consent or are at higher risk of harm.

Where you can join this trial?

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Verified Sites

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Other Sites

Site Name	City	Country	Status
Instytut Hematologii I Transfuzjologii	Warsaw	Poland
Specialized Hospital For Active Treatment Of Hematological Diseases EAD	Sofia	Bulgaria

Trial status

Country	Status	Recruitment Start
Bulgaria	Recruiting	25.03.2025
Poland	Not yet recruiting	25.03.2025

Trial locations

Investigated drugs:

Etranacogene Dezaparvovec

CSL222 (Etranacogene Dezaparvovec) is a gene therapy being studied for its effectiveness and safety in treating adults with severe or moderately severe Hemophilia B. This therapy involves delivering a functional copy of a gene to help the body produce a protein called Factor IX (FIX), which is deficient in people with Hemophilia B. The goal is to reduce bleeding episodes by enabling the body to produce its own FIX after a single dose of the therapy.

Hemophilia B – Hemophilia B is a genetic disorder where the blood does not clot properly due to a deficiency of a protein called Factor IX. This condition leads to prolonged bleeding after injuries, surgeries, or even spontaneously without any apparent cause. Individuals with Hemophilia B may experience frequent nosebleeds, easy bruising, and bleeding into joints and muscles, which can cause pain and swelling. Over time, repeated bleeding into joints can lead to joint damage and arthritis. The severity of symptoms can vary, with some individuals experiencing mild symptoms and others having more severe bleeding episodes. Hemophilia B is typically inherited, but in some cases, it can occur due to a spontaneous genetic mutation.

Trial ID:

2023-509590-23-00

Protocol code:

CSL222_3005

NCT ID:

NCT06003387

Trial Phase:

Therapeutic confirmatory (Phase III)

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Study on the Safety and Effectiveness of Etranacogene Dezaparvovec Gene Therapy for Adults with Severe or Moderately Severe Hemophilia B and AAV5 Antibodies

What is this study about?

Who Can Join the Study?

Who Cannot Join the Study?