Phase 3b Study of CSL222 Gene Therapy for Adults With Severe or Moderately Severe Hemophilia B and Detectable AAV5 Neutralizing Antibodies

What this Trial Is About

Researchers are assessing the risk of bleeding caused by the failure of CSL222s expected effect in adults with severe or moderately severe hemophilia B who have detectable pretreatment antibodies against adeno-associated virus serotype 5 AAV5 Nabs. This phase 3b study aims to evaluate the efficacy and safety of CSL222 gene therapy in this specific population. Participants will receive a single intravenous infusion of CSL222 Etranacogene Dezaparvovec at a dose of 2 x 1013 genome copies per kilogram on the first day. The study is open-label and multicenter, focusing on adults with severe or moderately severe hemophilia B and detectable pretreatment AAV5 neutralizing antibodies. This single-dose treatment is intended to assess gene therapy effects over time. During the study, participants will be monitored closely for bleeding rates from months 7 to 18 after treatment, as well as for adverse events and changes in liver health and blood factors up to 60 months post-treatment. Researchers will collect laboratory tests, liver ultrasounds, and questionnaires to assess quality of life and factor IX activity. Monitoring will include tracking of bleeding episodes, medication use, and potential side effects throughout the follow-up period, which may last several years.

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)