Trial results
AI generated results summary. Written by an AI model from the official source data and checked on a sample basis. It can contain mistakes, so confirm anything important against the original source. How we use AI
According to the results reported on ClinicalTrials.gov, this trial (NCT03549871) enrolled 80 people with haemophilia across two groups: 30 participants who had developed inhibitors (antibodies that block standard clotting treatments, making those treatments less effective) and 50 who had not. The trial was measuring how often participants experienced bleeding episodes — expressed as an annualised bleeding rate (ABR), meaning the estimated number of bleeds per person per year. All participants first went through a period of up to 168 days on their usual clotting factor or bypassing agent therapy, before switching to the investigational treatment fitusiran for up to around 190 days. The reported data shows that during the standard therapy period, the overall observed bleeding rate across participants was approximately 7.56 bleeds per person per year, with a statistically modelled ("estimated") figure of 7.48. During the fitusiran treatment period, the reported observed rate was approximately 3.19 bleeds per person per year, with the modelled estimate at 2.91. For bleeds that happened without any clear cause (called spontaneous bleeds), the reported observed rates were approximately 5.09 per person per year during standard therapy and 2.51 during the fitusiran period. For joint bleeds specifically, the reported observed rates were approximately 5.35 per person per year during standard therapy and 2.82 during the fitusiran period. These are the numbers as submitted — the trial was not designed as a direct head-to-head comparison between two groups receiving different treatments at the same time, so these figures reflect a before-and-after measurement within the same participants. These are the results as reported to ClinicalTrials.gov. They are not medical advice — always discuss what they mean for you with your doctor.
View full results on ClinicalTrials.gov ↗ · Read the linked publication on PubMed (PMID 38452197) ↗
These are the results as reported to ClinicalTrials.gov, not medical advice. Verify independently with the trial site and discuss what they mean for you with your doctor.
Phase 3 Haemophilia Trial, Completed
Who may be able to join
AI generated eligibility summary. Written by an AI model from the official source data and checked on a sample basis. It can contain mistakes, so confirm anything important against the original source. How we use AI
Who might be able to join this trial:
- You are male and aged 12 years or older.
- You have been diagnosed with severe hemophilia A or B, confirmed by specific blood test results showing very low levels of the clotting factor (Factor VIII below 1% or Factor IX at or below 2%).
- If you have developed antibodies that block your clotting factor treatment (called "inhibitors"): you have had at least 2 bleeding episodes in the last 6 months that needed a specific type of treatment called bypassing agents (BPAs).
- If you do NOT have inhibitors: you have had at least 1 bleeding episode in the last 12 months that needed clotting factor treatment.
- If you have inhibitors: you have been using bypassing agent therapy regularly for prevention and to treat bleeds for at least the last 6 months, and your blood test results meet certain antibody level thresholds (confirm with trial site).
- If you do not have inhibitors: you have been using clotting factor concentrates regularly for prevention and treatment for at least 6 months, your antibody levels are below a certain threshold, you have not used bypassing agents for at least 6 months, and you have not had immune tolerance therapy in the past 3 years.
- You have been on a regular preventative treatment plan for hemophilia A or B for at least 6 months before joining.
- In your doctor's opinion, you have been following your prescribed preventative treatment consistently for at least 6 months.
- You are willing and able to follow the study requirements and sign a consent form (or assent form if under 18).
Who may not be able to join:
- You have another bleeding disorder in addition to hemophilia A or B.
- Your blood test shows that a certain clotting-related protein (antithrombin) is functioning below 60% of normal (confirm with trial site).
- You have a medical condition that makes your blood more likely to clot than normal (a clotting disorder).
- You have a significant liver disease.
- You currently have an active Hepatitis C infection.
- You have an acute or ongoing Hepatitis B infection.
- You are HIV positive with a weakened immune system (CD4 count below 200 cells per microliter).
- You have a history of blood clots in your arteries or veins.
- Your kidneys are not working well enough (confirm with trial site for specific levels).
- You have a history of allergic reactions to multiple medications, or specifically to a type of molecule similar to the study drug (confirm with trial site).
- You have had problems tolerating injections given under the skin.
- You have any other health condition that your doctor believes would make it unsafe or unsuitable for you to participate.
Important: Always verify eligibility with the trial site directly before applying.
Based on publicly available eligibility criteria from ClinicalTrials.gov. Verify directly with the trial site before acting. This is not medical advice.
Contact this trial
Principal Investigator: Clinical Sciences & Operations, Sanofi
Australian sites
Contact details sourced from ClinicalTrials.gov. Verify directly with the trial site before attending.
GP referral letter
Print a one-page summary to share with your doctor.
Trial details
Where this trial is recruiting
1 site(s) in Australia. Confirm current status and contact details directly with the trial site.
Primary endpoints
Estimated Annualized Bleeding Rate (ABR); Observed Annualized Bleeding Rate (ABR)
Can't join this trial?
Data last synced from ClinicalTrials.gov: 28 July 2026. Trial status can change. Always verify current status directly with the trial site before making any decision.