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)

December 15, 2025 updated by: Genzyme, a Sanofi Company

An Open-label, 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

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

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Active, not recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

The estimated total time on the study for a participant is up to 90 months (including screening, treatment period and safety follow up period).

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
281

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 3

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Australia
    • New South Wales
      • Camperdown, New South Wales, Australia, 2050
        • Investigational Site Number : 0360001
    • Victoria
      • Prahran, Victoria, Australia, 3181
        • Investigational Site Number : 0360003
    • Western Australia
      • Murdoch, Western Australia, Australia, 6961
        • Investigational Site Number : 0360002
  • Canada
    • Quebec
      • Montreal, Quebec, Canada, H1T 2M4
        • Investigational Site Number : 1240001
  • China
      • Beijing, China, 100045
        • Investigational Site Number : 1560004
      • Beijing, China, 100730
        • Investigational Site Number : 1560007
      • Changsha, China, 410008
        • Investigational Site Number : 1560014
      • Chengdu, China, 610091
        • Investigational Site Number : 1560009
      • Guangzhou, China, 510515
        • Investigational Site Number : 1560002
      • Guiyang, China, 550004
        • Investigational Site Number : 1560011
      • Hangzhou, China, 89147
        • Investigational Site Number : 1560005
      • Jinan, China, 250013
        • Investigational Site Number : 1560008
      • Kunming, China, 650000
        • Investigational Site Number : 1560012
      • Lanzhou, China, 730000
        • Investigational Site Number : 1560013
      • Qingdao, China, 266555
        • Investigational Site Number : 1560010
      • Shanghai, China, 200025
        • Investigational Site Number : 1560003
      • Suzhou, China, 215006
        • Investigational Site Number : 1560006
  • Denmark
      • Copenhagen, Denmark, 2100
        • Investigational Site Number : 2080001
  • France
      • Lyon, France, 69677
        • Investigational Site Number : 2500002
      • Paris, France, 75015
        • Investigational Site Number : 2500003
  • Germany
      • Berlin, Germany, 10249
        • Investigational Site Number : 2760001
      • Leipzig, Germany, 04103
        • Investigational Site Number : 2760003
  • Hungary
      • Budapest, Hungary, 1134
        • Investigational Site Number : 3480002
  • India
      • Bangalore, India, 560034
        • Investigational Site Number : 3560001
      • Lucknow, India, 226003
        • Investigational Site Number : 3560005
      • Mumbai, India, 400 022
        • Investigational Site Number : 3560007
      • Pune, India, 411001
        • Investigational Site Number : 3560002
      • Pune, India, 411004
        • Investigational Site Number : 3560010
      • Ranipet, India, 632517
        • Investigational Site Number : 3560004
  • Ireland
      • Dublin, Ireland, 8
        • Investigational Site Number : 3720002
    • Dublin
      • Crumlin, Dublin, Ireland, 12
        • Investigational Site Number : 3720001
  • Israel
      • Ramat Gan, Israel, 5262100
        • Investigational Site Number : 3760001
  • Italy
    • Lombardy
      • Milan, Lombardy, Italy, 20122
        • Investigational Site Number : 3800002
    • Veneto
      • Padua, Veneto, Italy, 35128
        • Investigational Site Number : 3800004
  • Japan
      • Kitakyushu, Japan, 8078555
        • Investigational Site Number : 3920003
      • Nagoya, Japan, 4668560
        • Investigational Site Number : 3920001
      • Saitama, Japan, 330-8777
        • Investigational Site Number : 3920004
      • Tokyo, Japan, 1600023
        • Investigational Site Number : 3920008
    • Hyōgo
      • Nishinomiya, Hyōgo, Japan, 663-8501
        • Investigational Site Number : 3920002
    • Kanagawa
      • Isehara, Kanagawa, Japan, 2591193
        • Investigational Site Number : 3920005
  • Malaysia
      • Ampang, Malaysia, 68000
        • Investigational Site Number : 4580003
      • Johor Bahru, Malaysia, 80100
        • Investigational Site Number : 4580001
      • Kota Kinabalu, Malaysia, 88586
        • Investigational Site Number : 4580002
  • South Africa
      • Port Elizabeth, South Africa, 6001
        • Investigational Site Number : 7100002
  • South Korea
      • Seoul, South Korea, 3722
        • Investigational Site Number : 4100004
    • Busan
      • Busan, Busan, South Korea, 602-739
        • Investigational Site Number : 4100001
    • Daejeon
      • Daejeon, Daejeon, South Korea, 35233
        • Investigational Site Number : 4100002
    • Seoul-teukbyeolsi
      • Seoul, Seoul-teukbyeolsi, South Korea, 03722
        • Investigational Site Number : 4100003
  • Taiwan
      • Changhua, Taiwan, 500
        • Investigational Site Number : 1580002
      • Taichung, Taiwan, 40201
        • Investigational Site Number : 1580008
      • Taichung, Taiwan, 40705
        • Investigational Site Number : 1580004
      • Taipei, Taiwan, 100
        • Investigational Site Number : 1580003
      • Taipei, Taiwan, 110
        • Investigational Site Number : 1580001
      • Taipei, Taiwan, 112
        • Investigational Site Number : 1580005
      • Taoyuan, Taiwan, 33305
        • Investigational Site Number : 1580007
  • Turkey (Türkiye)
      • Adana, Turkey (Türkiye), 01130
        • Investigational Site Number : 7920002
      • Akdeniz, Turkey (Türkiye), 07059
        • Investigational Site Number : 7920004
      • Bornova, Turkey (Türkiye), 35100
        • Investigational Site Number : 7920012
      • Gaziantep, Turkey (Türkiye), 27100
        • Investigational Site Number : 7920006
      • Istanbul, Turkey (Türkiye), 34093
        • Investigational Site Number : 7920005
      • Izmir, Turkey (Türkiye), TR-35100
        • Investigational Site Number : 7920003
      • Kayseri, Turkey (Türkiye), 38039
        • Investigational Site Number : 7920008
      • Samsun, Turkey (Türkiye), 55200
        • Investigational Site Number : 7920007
  • Ukraine
      • Kyiv, Ukraine, 04060
        • Investigational Site Number : 8040001
      • Kyiv, Ukraine, 1135
        • Investigational Site Number : 8040003
      • Lviv, Ukraine, 79044
        • Investigational Site Number : 8040002
      • Mykolaiv, Ukraine, 54058
        • Investigational Site Number : 8040004
  • United Kingdom
      • Glasgow, United Kingdom, G4 0SF
        • Investigational Site Number : 8260004
    • London, City of
      • London, London, City of, United Kingdom, SE1 9RT
        • Investigational Site Number : 8260001
  • United States
    • Arizona
      • Phoenix, Arizona, United States, 85016
        • Phoenix Childrens Hospital Site Number : 8400009
    • California
      • Los Angeles, California, United States, 90027
        • Children's Hospital Los Angeles Site Number : 8400019
      • Orange, California, United States, 92868
        • Center for Inherited Blood Disorders (CIBD) Site Number : 8400016
    • Florida
      • Jacksonville, Florida, United States, 32207
        • Nemours Children's Clinic Site Number : 8400008
      • Tampa, Florida, United States, 33607
        • St Joseph's Children's Hospital of Tampa Site Number : 8400002
    • Illinois
      • Chicago, Illinois, United States, 60612-3863
        • Rush University Medical Center -1725 W Harrison St Site Number : 8400001
    • Massachusetts
      • Boston, Massachusetts, United States, 02114
        • ~Massachusetts General Hospital Site Number : 8400011
    • Michigan
      • Ann Arbor, Michigan, United States, 48109-5000
        • University of Michigan Hospital - 1500 E Medical Center Dr Site Number : 8400012
    • Nevada
      • Las Vegas, Nevada, United States, 89135-3011
        • Alliance for Childhood Diseases Site Number : 8400007
    • Ohio
      • Akron, Ohio, United States, 44308
        • Childrens Hospital Medical Center of Akron Site Number : 8400006

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

8 years and older (Child, Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

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
  • Male
  • 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.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Fitusiran
Participants will be administered fitusiran as a subcutaneous injection once monthly or every other month for up to 48 months post initiation of modified IMP dose/frequency or until fitusiran becomes commercially available, whichever comes first.
Drug: Fitusiran
Pharmaceutical form:solution for injection Route of administration: subcutaneous

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Number of participants with treatment emergent adverse events (TEAEs)
Time Frame: from study baseline (day 1) up to maximum 88 months
The number of participants experiencing any TEAEs, serious TEAEs, discontinuation due to TEAEs and death will be reported
from study baseline (day 1) up to maximum 88 months

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Annualized bleeding rate (ABR)
Time Frame: from first ever dose of fitusiran (day 1) up to maximum 78 months
Annualized bleeding rate (ABR) in the treatment period
from first ever dose of fitusiran (day 1) up to maximum 78 months
Annualized spontaneous bleeding rate
Time Frame: from first ever dose of fitusiran (day 1) up to maximum 78 months
Annualized spontaneous bleeding rate in the treatment period
from first ever dose of fitusiran (day 1) up to maximum 78 months
Annualized joint bleeding rate
Time Frame: from first ever dose of fitusiran (day 1) up to maximum 78 months
Annualized joint bleeding rate in the treatment period
from first ever dose of fitusiran (day 1) up to maximum 78 months
Changes in Haem-A-quality of life (QoL) score
Time Frame: from first ever dose of fitusiran (day 1) up to maximum 78 months
Change in Haem A QoL physical health score and total score in the treatment period (in participants ≥17 years of age) from first ever dose of fitusiran (day 1) up to maximum 78 months
from first ever dose of fitusiran (day 1) up to maximum 78 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Genzyme, a Sanofi Company

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Study Director: Clinical Sciences & Operations, Sanofi

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
January 9, 2019

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
November 5, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
November 5, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
November 25, 2018

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 26, 2018

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
November 27, 2018

Study Record Updates

Last Update Posted (Estimated)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
December 17, 2025

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
December 15, 2025

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
December 1, 2025

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • LTE15174
  • 2018-002880-25 (EudraCT Number)
  • U1111-1210-0018 (Registry Identifier: ICTRP)
  • 2023-508884-59 (Registry Identifier: CTIS)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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