Long-term Safety and Efficacy Study of Fitusiran in Patients With Hemophilia A or B, With or Without Inhibitory Antibodies to Factor VIII or IX (ATLAS-OLE)

  • End date
    Oct 19, 2026
  • participants needed
  • sponsor
    Genzyme, a Sanofi Company
Updated on 11 May 2022
severe haemophilia a
antihemophilic factor


Primary Objective:

To characterize the long-term safety and tolerability of fitusiran

Secondary Objectives:

  • To characterize the efficacy and long-term efficacy of fitusiran as assessed by the frequency of:
  • Bleeding episodes
  • Spontaneous bleeding episodes
  • Joint bleeding episodes
  • To characterize the effects of fitusiran on health-related quality of life (HRQOL) measures in participants ≥17 years of age


The estimated total time on study for each participant is up to 56 months which consists of a screening period of up to 60 days, an open label treatment period of up to 48 months and a follow up period of up to 6-month after the last dose of fitusiran. The duration of the treatment period and overall that of study participation, may exceed the intervals stated above for patient enrolled in the lower-dose cohort, to ensure a minimum of 18-month administration at this dosing regimen

Condition Hemophilia
Treatment fitusiran
Clinical Study IdentifierNCT03754790
SponsorGenzyme, a Sanofi Company
Last Modified on11 May 2022


Yes No Not Sure

Inclusion Criteria

Participant must be at least 12 years of age inclusive, at the time of signing the informed consent
Participants with severe hemophilia A or B who have completed a Phase 3 fitusiran clinical trial
Capable of giving signed informed consent which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in the protocol. In countries where legal age of majority is above 18 years, a specific ICF must also be signed by the participant's legally authorized representative

Exclusion Criteria

Completion of a surgical procedure within 14 days prior to screening, or currently receiving additional factor concentrate or BPA infusion for postoperative hemostasis
Current participation in immune tolerance induction treatment (ITI)
Current use of factor concentrates or bypassing agents (BPAs) as regularly administered prophylaxis designed to prevent spontaneous bleeding episodes except for participants requiring factor concentrates or BPAs prophylaxis during the study dosing pause period
Use of compounds other than factor concentrates or BPAs for hemophilia treatment
Current or prior participation in a gene therapy trial
Alanine aminotransferase (ALT) and/or Aspartate aminotransferase (AST) >1.5 × upper limit of normal reference range (ULN) for patients who are naïve to fitusiran at study start; ALT and/or AST > 5 x ULN for patients who were in the fitusiran arm in the parent study
Additional exclusions for participants not currently participating in a fitusiran trial at the time of enrollment in the lower dose cohort
Clinically significant liver disease
History of arterial or venous thromboembolism
The above information is not intended to contain all considerations relevant to a patient's
potential participation in a clinical trial
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Additional screening procedures may be conducted by the study team before you can be confirmed eligible to participate.

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If you are confirmed eligible after full screening, you will be required to understand and sign the informed consent if you decide to enroll in the study. Once enrolled you may be asked to make scheduled visits over a period of time.

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Complete your scheduled study participation activities and then you are done. You may receive summary of study results if provided by the sponsor.

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