A Study to Investigate Long-term Safety and Tolerability of Frexalimab in Participants With Multiple Sclerosis

November 10, 2026 updated by: Sanofi

A Phase 3 Extension Study to Investigate Long-term Safety and Tolerability of Frexalimab in Participants With Multiple Sclerosis.

Study LTS18002 is a global, multicenter, open-label (OL), Phase 3, long-term safety and efficacy extension study.

The purpose of this study is to provide continued access to frexalimab for participants with MS, and to evaluate the long-term safety and efficacy profile of frexalimab. This study will monitor delayed AEs, assess the durability of safety findings and characterize any emerging safety signals that may develop over an extended follow up period.

Study details include:

  • The study duration will be up to 4 years.

  • The OL treatment duration will be up to 96 weeks (corresponding to approximately 2 years) per participant.

  • There is an additional 24 weeks of safety follow up from the last dose of OL frexalimab for all participants (safety follow-up period/EOS: 4, 12 and 24 weeks after last investigational medicinal product(IMP) or OL frexalimab administration).

  • The number of visits over the 2-year duration will be dependent on subgroup assignment which is based on parent study from which the participant has entered the LTS18002 :

    1. ACT16877, EFC17504, EFC18098, and ASY22814 participants

      • Will have on-site visits every 12 weeks (9 visits)

        • Additionally, there will be 16 on-site visits for OL frexalimab administration (Week 4, 8, 16, 20, 28, 32, 40, 44, 52, 56, 64, 68, 76, 80, 88, and 92) for all participants EXCEPT those entering from EFC18098 (frexalimab open label administration is conducted at home via SC large volume (OBDS VT) device)

          • There will be 3 follow up visits beginning 4 weeks after the last administration of OL frexalimab

            • Home administration is allowed for participants from ACT16877, based on Investigator judgement, participant/caregiver training and local availability. Home nurse services are mandatory for at-home administration.

              • Home nurse services for at home administration may be considered for EFC17504 participants after Week 24 administration of OL frexalimab, based on availability. Participants that have initiated OL frexalimab via home administration during the parent study may continue to receive it in this manner.

                • NOTE: For participants from EFC17504, all on-site visits including monthly IMP administrations will include safety labs (biochemistry, hematology liver chemistry, and immunoglobulins) and physical exams

    2. EFC17919A/B participants

      • Will have on site visits every 12 weeks (9 visits)

        • Will have a total of 16 visits for OL frexalimab administration (Week 4, 8, 16, 20, 28, 32, 40, 44, 52, 56, 64, 68, 76, 80, 88, and 92)

          • Additionally, there will be up to 3 visits for administration of DB treatment (until results become available and randomization assignment availability).

            • Home nurse services for at home administration may be considered for EFC17919A/B participants after Week 24 administration of OL frexalimab, based on availability.

NOTE: all on-site visits including monthly IMP administrations will include safety labs (biochemistry, hematology liver chemistry, and immunoglobulins) and physical exams.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

2500

Phase

  • 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 Contact

  • Name: Trial Transparency email recommended (Toll free for US & Canada)
  • Phone Number: option 6 800-633-1610
  • Email: Contact-US@sanofi.com

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

Ages Eligible for Study

18 years to 60 years (Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

- Participants with relapsing multiple sclerosis(RMS) or non-relapsing secondary progressive multiple sclerosis(nrSPMS) who completed, on IMP, the Phase 2 ACT16877 study, or one of the four Phase 3 frexalimab studies in MS indication (EFC17919A and EFC17919B, EFC17504, EFC18098), or planned Phase 2 biomarker ASY22814.

Exclusion Criteria:

  • If IMP discontinuation criteria are met as per guidance
  • The participant is at risk for or has a persistent chronic, active (including fever ≥38°C and clinically unstable), recurring systemic infection or opportunistic infections (eg, PML See Appendix in protocol) as judged by the Investigator.
  • Notably low immunoglobulin G(IgG) levels, defined as a level that is 20% below the LLN, and/or notably low IgM level, defined as a level 10% below the LLN.
  • Participants who developed clinically relevant cardiovascular, hepatic, endocrine, neuropsychiatric or other major systemic disease making implementation of the protocol or interpretation of the study results difficult or that would put the participant at risk by participating in the extension study, as judged by the Investigator.
  • Clinical evidence, suspicion or significant risk for thromboembolic events, as well as myocardial infarction, stroke, and/or antiphospholipid syndrome and any participants requiring antithrombotic treatment.
  • Continued need for/chronic use of a prohibited concomitant medication.
  • Suicidal risk as per C-SSRS: if a participant scores "yes" on items 4 or 5 of the Suicidal Ideation Section, or "yes" on any item of the Suicidal Behavior Section.

The above information is not intended to contain all considerations relevant to a participant'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: Non-Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Frexalimab SC (OL)

Participants will be administered frexalimab subcutaneous
Drug: Frexalimab

Pharmaceutical form:Solution for injection-Route of administration:SC

Other Names:
  • SAR441344
Drug: Frexalimab

Pharmaceutical form:Solution for infusion-Route of administration:IV

Other Names:
  • SAR441344
Drug: MRI contrast-enhancing agents

Route of administration:IV
Experimental: Frexalimab IV (OL)

Participants will be administered frexalimab intravenously
Drug: Frexalimab

Pharmaceutical form:Solution for injection-Route of administration:SC

Other Names:
  • SAR441344
Drug: Frexalimab

Pharmaceutical form:Solution for infusion-Route of administration:IV

Other Names:
  • SAR441344
Drug: MRI contrast-enhancing agents

Route of administration:IV
Experimental: Frexalimab (DB)

For EFC17919A/B parent study participants: at Opt-in visit participants will continue to be administered f rexalimab through unblinding visit. Participants will receive placebo tablet once daily until the unblinding visit.
Drug: Frexalimab

Pharmaceutical form:Solution for injection-Route of administration:SC

Other Names:
  • SAR441344
Drug: Frexalimab

Pharmaceutical form:Solution for infusion-Route of administration:IV

Other Names:
  • SAR441344
Drug: MRI contrast-enhancing agents

Route of administration:IV

Drug: Teriflunomide Placebo

Pharmaceutical form:Tablet-Route of administration:Oral

Drug: Cholestyramine

Route of administration:oral

Drug: charcoal

Route of administration:oral
Active Comparator: Teriflunomide (DB)

For EFC17919A/B parent study participants: at Opt-in visit participants will continue to receive teriflunomide tablet. The placebo will be administered to participants at the same infusion rate and duration as for frexalimab from the opt-in visit until availability of results and unblinding.
Drug: MRI contrast-enhancing agents

Route of administration:IV

Drug: Cholestyramine

Route of administration:oral

Drug: charcoal

Route of administration:oral

Drug: Frexalimab Placebo

Pharmaceutical form:Solution for infusion-Route of administration:IV

Drug: Teriflunomide

Pharmaceutical form:Tablet-Route of administration:Oral

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Number of participants with Adverse Events(AEs)
Time Frame: up to to approximately 2.5 years since last participant in

Number of participants with Adverse Events(AEs), serious adverse event(SAEs), AEs leading to permanent study intervention discontinuation, adverse event of special interest(AESIs), local tolerability, clinically significant abnormalities in laboratory tests, Columbia-Suicide Severity Rating Scale(C-SSRS)
up to to approximately 2.5 years since last participant in

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Participants from EFC17919A, EFC17919B, and EFC17504 studies only: time to onset of 6-month composite confirmed disability worsening(cCDW) for RMS or composite confirmed disability progression(cCDP) for nrSPMS
Time Frame: up to to approximately 2.5 years since last participant in
up to to approximately 2.5 years since last participant in
Time to onset of individual components of the composite, confirmed over 3 months or 6 months EDSS for all prior study participants 9-HPT, T25FW test (participants rolling over from EFC17504, EFC17919A, and EFC17919B)
Time Frame: up to to approximately 2.5 years since last participant in
up to to approximately 2.5 years since last participant in
Progression independent of relapse activity defined as the time to onset of 6-month cCDW
Time Frame: up to to approximately 2.5 years since last participant in

Progression independent of relapse activity defined as the time to onset of 6-month cCDW, defined by either no prior relapse or an onset more than 90 days after the start date of the last Investigator reported relapse (participants rolling over from EFC17919A and EFC17919B)
up to to approximately 2.5 years since last participant in
Number of new and/or enlarging T2-hyperintense lesions per year as detected by MRI
Time Frame: up to to approximately 2.5 years since last participant in
up to to approximately 2.5 years since last participant in
Total number of new GdE T1 lesions per year as detected by MRI
Time Frame: up to to approximately 2.5 years since last participant in
up to to approximately 2.5 years since last participant in
Change from baseline at scheduled visits in total volume of T2-hyperintense lesions as detected by brain MRI
Time Frame: up to to approximately 2.5 years since last participant in
up to to approximately 2.5 years since last participant in
ARR assessed by confirmed protocol defined relapses
Time Frame: up to to approximately 2.5 years since last participant in
up to to approximately 2.5 years since last participant in
antidrug antibodys(ADAs) incidence
Time Frame: up to to approximately 2.5 years since last participant in
up to to approximately 2.5 years since last participant in
Change from baseline in serum immunoglobulin(Ig) levels
Time Frame: up to to approximately 2.5 years since last participant in
up to to approximately 2.5 years since last participant in

Collaborators and Investigators

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

Sponsor

Sanofi

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 (Estimated)

February 15, 2027

Primary Completion (Estimated)

May 16, 2031

Study Completion (Estimated)

May 16, 2031

Study Registration Dates

First Submitted

November 3, 2026

First Submitted That Met QC Criteria

November 10, 2026

First Posted (Actual)

November 12, 2026

Study Record Updates

Last Update Posted (Actual)

November 12, 2026

Last Update Submitted That Met QC Criteria

November 10, 2026

Last Verified

November 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • LTS18002
  • 2026-525688-41 (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

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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