A Study to Assess the Safety, Tolerability, Efficacy, Pharmacokinetics, and Immunogenicity of Intravenous Administration of ARGX-119 in Pediatric Participants Aged 5 to Less Than 18 Years With Spinal Muscular Atrophy (Sparkle)

September 10, 2026 updated by: argenx

A Phase 2 Double-Blinded, Randomized, Placebo-Controlled Study to Assess the Safety, Tolerability, Efficacy, Pharmacokinetics, and Immunogenicity of Intravenous Administration of ARGX-119 in Pediatric Participants Aged 5 to Less Than 18 Years With Spinal Muscular Atrophy

This study aims to find the correct dose of ARGX-119 for children with SMA. The study will also look at how safe the study drug is, how well it works, how it moves through the body, and how the immune system responds to it. The study consists of a double-blinded treatment period (DBTP) where participants will either receive ARGX-119 IV or placebo IV, in addition to disease-modifying therapy (DMT) for 24 weeks. Participants who complete the DBTP will enter the open-label active-treatment extension period (ATEP) during which all participants will receive ARGX-119 IV up to 100 weeks (approximately 2 years).

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
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

This phase 2 study aims to establish proof of concept with the age-appropriate dose of ARGX-119 in ambulant pediatric patients with spinal muscular atrophy (SMA). Despite available treatments, there remains an unmet medical need for patients with SMA. Neuromuscular junction (NMJ) dysfunction contributes to the pathophysiology of SMA, including muscle weakness and fatigability. Activation of muscle-specific kinase (MuSK) by ARGX-119 may stabilize and improve NMJ function in patients with SMA, reducing muscle weakness and fatigability, and improving quality of life.

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 (Estimated)

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.
60

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 2

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

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • United Kingdom
    • Cambridgeshire
      • Cambridge, Cambridgeshire, United Kingdom, CB2 0QQ
        • Recruiting
        • Addenbrooke's Hospital
        • Contact:
        • Principal Investigator:
          • Deepa Krishnakumar
    • Greater London
      • London, Greater London, United Kingdom, WC1N 3JH
        • Not yet recruiting
        • Great Ormond Street Hospital for Children
        • Principal Investigator:
          • Mariacristina Scoto
        • Contact:
    • Oxfordshire
      • Oxford, Oxfordshire, United Kingdom, OX3 9DU
        • Not yet recruiting
        • MDUK Oxford Neuromuscular Centre
        • Principal Investigator:
          • Laurent Servais
        • Contact:
    • South Yorkshire
      • Sheffield, South Yorkshire, United Kingdom, S10 2TH
        • Recruiting
        • Sheffield Children's Hospital
        • Principal Investigator:
          • Min Ong
        • Contact:
    • Strathclyde
      • Glasgow, Strathclyde, United Kingdom, G51 4TF
        • Recruiting
        • Royal Hospital for Children
        • Contact:
        • Principal Investigator:
          • Shuko Joseph
    • West Midlands
      • Birmingham, West Midlands, United Kingdom, B9 5SS
        • Recruiting
        • Birmingham Heartlands Hospital
        • Contact:
        • Principal Investigator:
          • Deepak Parasuraman
    • West Yorkshire
      • Leeds, West Yorkshire, United Kingdom, LS1 3EX
        • Recruiting
        • Leeds General Infirmary
        • Principal Investigator:
          • Anne-Marie Childs
        • Contact:
  • United States
    • Arkansas
      • Little Rock, Arkansas, United States, 72202
        • Recruiting
        • Arkansas Children's Hospital
        • Contact:
        • Principal Investigator:
          • Kapil Arya, Dr.
    • California
      • San Diego, California, United States, 92123
        • Withdrawn
        • Rady Childrens Hospital
      • Stanford, California, United States, 94305
        • Recruiting
        • Stanford University Medical Center
        • Contact:
        • Principal Investigator:
          • Carolina Tesi Rocha, Dr.
    • Connecticut
      • Hartford, Connecticut, United States, 06106
        • Recruiting
        • Connecticut Children's Medical Center
        • Contact:
        • Principal Investigator:
          • Gyula Acsadi, Dr.
    • Florida
      • Kissimmee, Florida, United States, 34746
    • Illinois
      • Chicago, Illinois, United States, 60611
        • Recruiting
        • Ann & Robert H. Lurie Children's Hospital of Chicago
        • Contact:
        • Principal Investigator:
          • Nancy Kuntz, Dr.
    • Iowa
      • Iowa City, Iowa, United States, 52242
        • Recruiting
        • University of Iowa Stead Family Children's Hospital
        • Contact:
        • Principal Investigator:
          • Katherine Mathews, Dr.
    • Maryland
      • Baltimore, Maryland, United States, 21205
        • Not yet recruiting
        • The Johns Hopkins Hospital
        • Contact:
        • Principal Investigator:
          • Jessica Nance, Dr.
    • Massachusetts
      • Boston, Massachusetts, United States, 02115
    • Missouri
      • Columbia, Missouri, United States, 65212
        • Not yet recruiting
        • The Curators of the University of Missouri on behalf of University of Missouri Health Care
        • Contact:
        • Principal Investigator:
          • Jane Emerson, Dr.
    • New York
      • New York, New York, United States, 10032
        • Not yet recruiting
        • Columbia University Herbert Irving Comprehensive Cancer Center
        • Contact:
        • Principal Investigator:
          • Claudia Chiriboga, Dr.
    • North Carolina
      • Hillsborough, North Carolina, United States, 27278
        • Recruiting
        • Rare Disease Research NC, LLC
        • Contact:
        • Principal Investigator:
          • Edward Smith, Dr.
    • Pennsylvania
      • Philadelphia, Pennsylvania, United States, 19104
        • Not yet recruiting
        • Children's Hospital Philadelphia - Neurology
        • Contact:
        • Principal Investigator:
          • John Brandsema, Dr.
    • Texas
      • Flower Mound, Texas, United States, 75028
        • Recruiting
        • Neurology Rare Disease Center
        • Principal Investigator:
          • Diana Castro, Dr.
        • Contact:
      • Houston, Texas, United States, 77030
        • Recruiting
        • Texas Children's Hospital
        • Contact:
        • Principal Investigator:
          • Timothy Lotze, Dr.
    • Virginia
      • Norfolk, Virginia, United States, 23507
        • Not yet recruiting
        • Childrens Hospital of The Kings Daughters
        • Contact:
        • Principal Investigator:
          • Crystal Proud, Dr.

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

  • Child

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Is aged ≥5 to <18 years when completing the informed consent process, defined as providing informed assent according to local regulations and having a parent or guardian sign the ICF, and can comply with protocol
  • requirements.
  • Has documented historical genetic diagnosis of 5q-SMA.
  • Currently receiving a stable SMA treatment regimen (nusinersen or risdiplam) and/or have a history of onasemnogene abeparvovec treatment
  • Must be able to walk at least 50 meters without walking aids in the 6MWT at screening

Exclusion Criteria:

  • Known medical condition that would interfere with an accurate assessment of SMA, confound the results of the study, or put the participant at undue risk, as assessed by the investigator
  • Recent major surgery, except spinal fusion, within 3 months of screening or intends to have major surgery during the study
  • Current or previous administration of antimyostatin therapies in the past 6 months
  • Severe scoliosis (defined as curvature >40°) and/or contractures at screening. o History of spinal fusion within 6 months before screening or planned during the study
  • Respiratory insufficiency, defined by the medical necessity for invasive or noninvasive ventilation for daytime treatment while awake. Ventilation used overnight or during daytime naps is acceptable.

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: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

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: DBTP - ARGX-119 IV
Participants receive ARGX-119 IV during the DBTP
Biological: ARGX-119 IV
Intravenous infusion of ARGX-119
Placebo Comparator: DBTP - Placebo IV
Participants receive placebo IV during the DBTP
Other: Placebo IV
Intravenous infusion of placebo
Placebo Comparator: ATEP - ARGX-119 IV
Participants receive ARGX-119 IV during the ATEP. Participants from ARGX-119 IV arm in the DBTP will receive placebo once to maintain the DBTP blinding
Other: Placebo IV
Intravenous infusion of placebo
Biological: ARGX-119 IV
Intravenous infusion of ARGX-119

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
Incidence of AEs
Time Frame: Up to 124 weeks
Adverse Events
Up to 124 weeks
Incidence of SAEs
Time Frame: Up to 124 weeks
Serious Adverse Events
Up to 124 weeks
Change in RHS total score from baseline to week 24 of the double blinded treatment period (DBTP)
Time Frame: Up to 24 weeks
The RHS (Revised Hammersmith Scale) is a validated 36-item scale developed to evaluate the spectrum of gross motor function. Maximum total score; 69 (optimal motor function)
Up to 24 weeks

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
Change from baseline over time for the 6MWT - distance and fatigue index
Time Frame: Up to 124 weeks
In the 6MWT (6-minute walk test) participants will be instructed to walk as fast as possible without jogging or running along a 25- meter linearly marked course for 6 minutes without using walking devices or assistance. Distance walked over the entire 6-minute period, and other parameters, will be determined
Up to 124 weeks
ARGX-119 serum concentrations over time
Time Frame: Up to 124 weeks
ARGX-119 serum concentrations over time
Up to 124 weeks
Incidence of antidrug antibodies (ADA) against ARGX-119
Time Frame: Up to 124 weeks
Incidence of antidrug antibodies (ADA) against ARGX-119
Up to 124 weeks

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.
argenx

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.
December 19, 2025

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.
May 28, 2029

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.
May 28, 2029

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).
December 15, 2025

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.
December 15, 2025

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.
December 17, 2025

Study Record Updates

Last Update Posted (Actual)

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.
September 14, 2026

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.
September 10, 2026

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.
September 1, 2026

More Information

Terms related to this study

Keywords

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.
  • ARGX-119-24-SMA-2001
  • 2025 (U.S. NIH Grant/Contract: Faculty of Social Sciences Scientific Grant at the University of Gdańsk)
  • 2025-523496-32-00 (Ctis)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

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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