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)

What this study is about

The purpose of this study is to assess the risk of bleeding due to failure of expected pharmacological action of CSL222 in adults with severe or moderately severe hemophilia B with detectable pretreatment AAV5 Nabs.

Who can join (things the study team will check)

✅ You may be able to join if…

• Considered legally an adult, as defined by country regulations.
• Has 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 is on continuous routine FIX prophylaxis.
• Has 2 consecutive detectable AAV5 NAb titer results between Screening and Visit L-Final using a validated AAV5 NAb assay (based on central laboratory results).
• Has greater than (>) 150 previous exposure days to FIX replacement therapy.
• Has been on stable FIX prophylaxis for at least 2 months before Screening.
• Has demonstrated capability to independently, accurately, and in a timely manner complete the eDiary during the Lead-in Period, as judged by the investigator.
• Acceptance to adhere to contraception guidelines.
• Able to provide informed consent after receipt of verbal and written information about the study.
• Investigator believes that the participant (or the participant's legally acceptable representative[s]) understands the nature, scope, and possible consequences of the study and is able to adhere to the study procedures.

🚫 You may not be able to join if…

• • History of FIX inhibitors or positive FIX inhibitor test at Prescreening, Screening or Visit L-Final (based on central laboratory results).
• • Screening or Visit L-Final laboratory values (based on central laboratory results) of total bilirubin > 2 × the upper limit of normal (ULN) (except if caused by Gilbert's syndrome).
• • Screening or Visit L-Final laboratory values (based on central laboratory results) of any of the following laboratory abnormalities:
• a) ALT > 2 × the ULN
• b) AST > 2 × the ULN
• c) Alkaline phosphatase > 2 × the ULN
• d) Serum creatinine > 2 × the ULN
• e) Hemoglobin less than (<) 8 g/dL
• • Any condition other than hemophilia B resulting in an increased bleeding tendency.
• • Thrombocytopenia, defined as a platelet count <50 × 10\^9/L, at Screening or Visit L Final (based on central laboratory results).
• • Any uncontrolled or untreated infection (human immunodeficiency virus [HIV], hepatitis B virus [HBV] and hepatitis C virus [HCV], or any other significant concurrent, uncontrolled medical condition 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.
• • Known history of allergy to corticosteroids or known medical condition that would require chronic administration of oral corticosteroids.
• • Known uncontrolled allergic conditions or allergy / hypersensitivity to any component of the CSL222 excipients (ie, sucrose, potassium chloride, potassium dihydrogen phosphate, sodium chloride, and disodium hydrogen phosphate).
• • Previous AAV5 gene therapy treatment.
• • Receipt of an experimental agent or device within 60 days before Screening until the end of the study.

Where this trial is running

• University of California, San Diego (UCSD), San Diego, California, United States
• University of Michigan, Ann Arbor, Michigan, United States
• Hemophilia Center of Western Pennsylvania (HCWP), Pittsburgh, Pennsylvania, United States
• Royal Prince Alfred Hospital, Camperdown, New South Wales, Australia
• Royal Brisbane Hospital, Herston, Queensland, Australia
• Royal Adelaide Hospital, Adelaide, South Australia, Australia
• The Alfred Hospital, Melbourne, Victoria, Australia
• McMaster University - Hamilton, Hamilton, Ontario, Canada
• Queen Mary Hospital, Hong Kong, Hong Kong
• Prince of Wales Hospital Chinese University of Hong Kong, Shatin, Hong Kong
• Sheba Medical Center, Tel Litwinsky, Israel
• Centro de Investigacion Clinica GRAMEL S.C., Mexico City, Mexico City, Mexico

+ 15 more sites.

Who to contact

Trial Registration Coordinator · 1-610-878-4697 · clinicaltrials@cslbehring.com

It's completely normal to call and ask questions before deciding anything. Mention the study ID: NCT06003387.