Actively Recruiting
Phase 3b Open-label Study of CSL222 Gene Therapy in Adults With Severe or Moderately Severe Hemophilia B and Detectable AAV5 Neutralizing Antibodies
Led by CSL Behring · Updated on 2026-03-17
35
Participants Needed
26
Research Sites
182 weeks
Total Duration
On this page
AI-Summary
What this Trial Is About
This trial studies adults with severe or moderately severe hemophilia B who have detectable neutralizing antibodies against adeno-associated virus serotype 5 (AAV5). The purpose is to assess the risk of bleeding due to possible failure of the pharmacological action of CSL222 gene therapy in this group. CSL222 is being evaluated by CSL Behring in a phase 3b, open-label study to better understand its safety and efficacy. Participants will receive a single intravenous infusion of CSL222, delivering 2 × 10^13 genome copies per kilogram on the first day. This gene therapy aims to provide a one-time treatment targeting the underlying FIX deficiency in hemophilia B. The study does not involve placebo or multiple doses, focusing solely on the effects of this single administration. Throughout the study, participants will be closely monitored for bleeding rates between months 7 to 18 after treatment, as well as potential side effects and changes in liver function, blood counts, and Factor IX activity for up to 60 months. Assessments include laboratory tests, ultrasound scans, and patient diaries. Researchers will also evaluate quality of life and corticosteroid use. The total follow-up period allows for long-term safety and effectiveness observation.
CONDITIONS
Brief Title
Efficacy and Safety of CSL222 (Etranacogene Dezaparvovec) Gene Therapy in Adults With Hemophilia B With Pretreatment Adeno-associated Virus Serotype 5 (AAV5) Neutralizing Antibodies (Nabs)
Who Can Participate
Eligibility Criteria
You may qualify if you...
- Considered legally an adult as defined by local regulations
- Diagnosed with congenital hemophilia B with severe or moderately severe Factor IX deficiency (≤ 2% normal levels)
- On continuous routine Factor IX prophylaxis
- Have two consecutive detectable AAV5 neutralizing antibody results between screening and final visit
- Have more than 150 previous exposure days to Factor IX replacement therapy
- Have been on stable Factor IX prophylaxis for at least 2 months before screening
- Able to independently and accurately complete an electronic diary
- Willing to follow contraception guidelines
- Able to give informed consent and adhere to study procedures
You will not qualify if you...
- History of Factor IX inhibitors or positive inhibitor test at screening or final visit
- Total bilirubin > 2 times upper limit of normal except if due to Gilbert's syndrome
- Laboratory abnormalities at screening/final visit: ALT > 2x ULN, AST > 2x ULN, alkaline phosphatase > 2x ULN, serum creatinine > 2x ULN, hemoglobin < 8 g/dL
- Any condition other than hemophilia B causing increased bleeding risk
- Thrombocytopenia with platelet count < 50 x 10^9/L
- Uncontrolled or untreated infections including HIV, HBV, HCV, or other significant medical conditions
- Known allergy to corticosteroids or need for chronic oral corticosteroids
- Uncontrolled allergic conditions or allergy to CSL222 excipients
- Previous treatment with AAV5 gene therapy
- Receipt of experimental agent or device within 60 days before screening until study end
AI-Screening
AI-Powered Screening
Complete this quick 3-step screening to check your eligibility
Your Study Journey
Duration - 2 to 4 weeks
Participants are screened for eligibility to participate in the trial.
1 visit (in-person)
Duration - Single day
Participants receive a single intravenous infusion of CSL222 gene therapy on Day 1.
1 infusion visit (in-person)
Duration - Up to 60 months after treatment
Participants are monitored for safety, efficacy, and adverse events for up to 60 months after treatment.
Regular visits during the follow-up period
Trial Site Locations
Total: 26 locations
1
University of California, San Diego (UCSD)
San Diego, California, United States, 92121
Actively Recruiting
2
University of Michigan
Ann Arbor, Michigan, United States, 48109
Actively Recruiting
3
Royal Prince Alfred Hospital
Camperdown, New South Wales, Australia, 2050
Actively Recruiting
4
Royal Brisbane Hospital
Herston, Queensland, Australia, 4029
Actively Recruiting
5
Royal Adelaide Hospital
Adelaide, South Australia, Australia, 5000
Actively Recruiting
6
The Alfred Hospital
Melbourne, Victoria, Australia, 3004
Actively Recruiting
7
McMaster University - Hamilton
Hamilton, Ontario, Canada, L8N 3Z5
Actively Recruiting
8
Queen Mary Hospital
Hong Kong, Hong Kong, 999077
Actively Recruiting
9
Prince of Wales Hospital Chinese University of Hong Kong
Shatin, Hong Kong, 999077
Actively Recruiting
10
Sheba Medical Center
Tel Litwinsky, Israel, 5265601
Actively Recruiting
11
Centro de Investigacion Clinica GRAMEL S.C.
Mexico City, Mexico City, Mexico, 3720
Actively Recruiting
12
King Faisal Specialist Hospital and Research Center
Riyadh, Saudi Arabia, 11471
Actively Recruiting
13
National University Hospital
Singapore, Singapore, 110974
Actively Recruiting
14
Singapore General Hospital
Singapore, Singapore, 169608
Actively Recruiting
15
Haemophilia Comprehensive Care Centre
Johannesburg, South Africa, 2193
Actively Recruiting
16
Kyungpook National University Hospital
Daegu, South Korea, 41944
Actively Recruiting
17
Kyung Hee University Hospital at Gangdong
Seoul, South Korea, 05278
Actively Recruiting
18
Severance Hospital, Yonsei University Health System
Seoul, South Korea, 3722
Actively Recruiting
19
Tri-Service General Hospital
Taipei, Neihu District, Taiwan, 114
Actively Recruiting
20
Kaohsiung Medical University Chung-Ho Memorial Hospital (KMUH)
Kaohsiung City, Sanmin District, Taiwan, 80756
Actively Recruiting
21
Changhua Christian Hospital (CCH)
Chang-hua, Taiwan, 500
Actively Recruiting
22
Taichung Veterans General Hospital -
Taichung, Taiwan, 40705
Actively Recruiting
23
National Taiwan University Hospital
Taipei, Taiwan, 100225
Actively Recruiting
24
Ege University Medical Faculty
Bornova, Turkey (Türkiye), 35100
Actively Recruiting
25
Gaziantep University Sahinbey Research and Practice Hospital
Gaziantep, Turkey (Türkiye), 27310
Actively Recruiting
26
Özel Acibadem Adana Hastanesi
Seyhan, Turkey (Türkiye), 01130
Actively Recruiting
Research Team
T
Trial Registration Coordinator
How is the study designed?
Study Type
INTERVENTIONAL
Masking
NONE
Allocation
NA
Model
SINGLE_GROUP
Primary Purpose
TREATMENT
Number of Arms
1
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