Phase 3, Open-label, Single-dose Study of CSL222 in Adolescent Male Subjects (≥ 12 to < 18 Years of Age) With Severe or Moderately Severe Hemophilia B
NCT ID: NCT07080905
Last Updated: 2025-12-17
Study Results
The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.
Basic Information
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RECRUITING
PHASE3
20 participants
INTERVENTIONAL
2025-07-28
2033-10-24
Brief Summary
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Detailed Description
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Conditions
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Study Design
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NA
SINGLE_GROUP
TREATMENT
NONE
Study Groups
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CSL222
Participants will receive CSL222 as a single intravenous (IV) infusion of 2 × 10\^13 genome copies per kilogram of body weight (gc/kg).
CSL222 (Adeno-associated viral vector serotype 5 [AAV5]-hFIXco-Padua)
Administered as a single IV infusion.
Interventions
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CSL222 (Adeno-associated viral vector serotype 5 [AAV5]-hFIXco-Padua)
Administered as a single IV infusion.
Other Intervention Names
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Eligibility Criteria
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Inclusion Criteria
* Aged ≥138 months (11 years and 6 months) to less than (\<) 206 months (17 years and 2 months) at the time of informed consent / assent.
* Congenital hemophilia B with known severe or moderately severe FIX deficiency (less than or equal to \[≤\] 2% of normal circulating FIX) for which the participant has been on continuous FIX prophylaxis.
* On stable continuous FIX prophylaxis for at least 2 months before Screening.
* Minimum of 75 previous exposure days of treatment with FIX protein before Screening.
Completed the Lead-in Period: minimum of 6 months (26 weeks) of lead-in data collected and eligibility has been confirmed.
* Aged ≥ 12 to \< 18 years at the time of CSL222 treatment.
Exclusion Criteria
* Screening laboratory values (based on central laboratory results):
* Total bilirubin \> 2 × the upper limit of normal (ULN).
* Alanine aminotransferase (ALT) \> 2 × the ULN.
* Aspartate aminotransferase (AST) \> 2 × the ULN.
* Alkaline phosphatase (ALP) \> 2 × the ULN.
* Serum creatinine \> 2 × the ULN.
* Hemoglobin \< 8 g/dL.
* Any condition other than hemophilia B resulting in an increased bleeding tendency.
* Thrombocytopenia, defined as a platelet count below 50 × 10\^9/L, at screening (based on central laboratory results).
* Any uncontrolled or untreated infection (human immunodeficiency virus, hepatitis C, etc) or any other significant concurrent, uncontrolled medical condition, as evaluated by the investigator, including, but not limited to renal, hepatic, cardiovascular, hematological, gastrointestinal, endocrine, pulmonary, neurological, cerebral, or psychiatric disease, alcoholism, drug dependency, or any other psychological disorder evaluated by the investigator to interfere with adherence to the Clinical Study Protocol procedures or with the degree of tolerance to CSL222.
Positive FIX inhibitor test at Visit L-Final (based on central laboratory results)
* AAV5 NAb titer \> 1:900 as assessed at Visit LX (last visit before Visit L-Final).
* Visit L-Final laboratory values (based on central laboratory results) of:
* Total bilirubin \> 2 × the ULN
* ALT \> 2 × the ULN.
* AST \> 2 × the ULN.
* ALP \> 2 × the ULN.
* Serum creatinine \> 2 × the ULN.
* Hemoglobin \< 8 g/dL.
* Thrombocytopenia, defined as a platelet count below 50 × 10\^9/L, at Visit L-Final (based on central laboratory results).
138 Months
206 Months
MALE
No
Sponsors
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CSL Behring
INDUSTRY
Responsible Party
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Principal Investigators
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Study Director
Role: STUDY_DIRECTOR
CSL Behring
Locations
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University of Florida - 84000399
Gainesville, Florida, United States
University of Michigan Medical Center - 84000491
Ann Arbor, Michigan, United States
Countries
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Central Contacts
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Facility Contacts
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Other Identifiers
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2023-505805-18-00
Identifier Type: CTIS
Identifier Source: secondary_id
CSL222_3004
Identifier Type: -
Identifier Source: org_study_id