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
Study Details
- Hemophilia B
- Key Inclusion Criteria for the Lead-in Period:
- Assigned male sex at birth
- 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.
- Additional Key Inclusion Criteria for the Treatment Period:
- 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.
- Key Exclusion Criteria for the Lead-in Period:
- History of FIX inhibitors or positive FIX inhibitor test at Screening (based on central laboratory results).
- 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.
- Additional Key Exclusion Criteria for the Treatment Period:
- 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).
Protocol Summary
This study is looking at how safe it is to switch from emicizumab to Mim8, in people with haemophilia A. Mim8 is a new medicine that is used to prevent bleeding episodes in people with haemophilia A. Mim8 works by replacing the function of the missing clotting factor VIII (FVIII). Mim8 will be injected under the skin using a pen-injector either once every week, once every two weeks or once every month. The participants will be trained in using the pen injector. The participants can choose themselves, in collaboration with the study doctor how often they get Mim8 in this study. When the participant will get their first Mim8 injection depends on their current treatment with emicizumab. The participants will get their first Mim8 injection at Visit 2. Participants will have between 6 and 27 Mim8 injections. The total number of injections participants will have depends on their dosing frequency. The study will last for about 6-12 months. While taking part in this study, there are some restrictions about what medicine participant can use. The study doctor will tell the participants more about this. In case the participants experience bleeds, these can be treated with additional haemostatic medicine as agreed with the study doctor. Female participants cannot take part if they are pregnant, breast-feeding or plan to get pregnant during the study period.