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Can a muscle-boosting antibody help people with spinal muscular atrophy over the long haul?

NCT ID NCT05626855

Disease control Sponsor: Scholar Rock, Inc. Source: ClinicalTrials.gov ↗

What the study statuses mean

This study's is highlighted.

Recruitment status, easiest to join first

Recruiting now
This trial is taking on new participants right now.
Not yet recruiting
Registered, but not yet taking participants.
By invitation only
Not open to general applications. Only people the study team invites can take part.
Paused
Paused for now. It may or may not start again.
Ongoing This study
Running, but no longer taking on new participants.
Completed
The trial has finished. Results may not be published yet.
Stopped early
Stopped early, before it reached the end. That can be for many reasons, including safety.
Cancelled
Cancelled before anyone took part.

Expanded access (not trials)

Expanded access
Not a trial. This treatment can be requested outside a study, case by case, for people who qualify.
Expanded access (paused)
Not a trial. The treatment can normally be requested outside a study, but is unavailable right now.
Expanded access (ended)
Not a trial. The treatment could once be requested outside a study, but no longer can.
Approved
The treatment has been approved, so it is available normally rather than through this programme.

When the status isn't known

Details not published
The full record has not been published yet, so there is little to show here.
Status unknown
This status has not been confirmed recently, so it may be out of date.

First seen Sep 01, 2026 · Last updated Sep 02, 2026 · Updated 1 time

Summary

This trial tests the long-term safety and effectiveness of apitegromab, an investigational antibody that blocks myostatin, a protein that limits muscle growth. People with type 2 or type 3 spinal muscular atrophy who completed earlier apitegromab studies can join. Researchers will track side effects and measure changes in motor function over time to see if the drug keeps helping.

What this could mean

Our plain-language read of the trial. This is informational only, not medical advice or a prediction.

Active substance
apitegromab, an investigational antibody that targets myostatin to support muscle growth and strength
What this could lead to
If it works, this could support apitegromab as a long-term treatment to help preserve or improve muscle function in people with spinal muscular atrophy.
What could go wrong
This is an extension study, so it builds on earlier trials and does not prove the drug works on its own. Long-term use may still carry risks, and results may not apply to all patients.
Why investors are watching

Scholar Rock is running ONYX, a long-term extension study of its drug apitegromab in patients with type 2 and type 3 spinal muscular atrophy who finished earlier trials. For a micro-cap company with few products, this study's safety and efficacy data will shape whether the drug can support a commercial launch and whether the company can sustain itself.

If it works: Positive long-term safety and efficacy results could support regulatory approval and broader use of apitegromab, giving Scholar Rock its first marketable product and a path to revenue.

If it fails: If the study shows safety problems or weak long-term benefit, regulators may reject the drug or restrict its use, which could leave Scholar Rock without a viable product. Trials fail often, and an extension study can still reveal issues that stop development.

AI-written from the trial record. Speculative, and not investment advice.

This is an AI summary of the original study and may miss details. Read our disclaimer.

Study facts

What this study's own registry entry says, in plain language.

Phase

Phase 3

Large-scale testing in a bigger group. Usually the last step before a treatment can be approved.

Participants

238 people

The number who actually took part.

Started

Apr 2023

Expected to finish

May 2029

An estimate. End dates often move.

Lead sponsor

A company

The lead sponsor is a pharmaceutical, biotech, or medical-device company.

Who can take part

This study's own entry requirements. Only the study team can say for certain whether you qualify.

Ages

2 years and older

Sex

Anyone

Healthy volunteers

Not accepted

This study is not open to healthy volunteers. The entry requirements below say who it is open to.

Show the full entry requirements

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Patients have completed the Phase 2 TOPAZ (Study SRK-015-002) trial or the Phase 3 SAPPHIRE (Study SRK-015-003) trial. (For TOPAZ, completed is defined as completion of Visit EC14 in Extension Period C or participating in TOPAZ at the time the trial is ended. For SAPPHIRE, completed is defined as completion of Visit 14 or participating in SAPPHIRE at the time the trial is ended) * Estimated life expectancy \>2 years from the Baseline Visit (Day 1) * Able to receive study drug infusions and provide blood samples through the use of a peripheral IV or a long-term IV access device that the patient has placed for reasons independent from the trial * Able to adhere to the requirements of the protocol, including travel to the trial site and completing all trial procedures and trial visits * Females of childbearing potential must have a negative pregnancy test at the Baseline Visit and agree to use at least 1 highly effective method of contraception throughout the trial and for 20 weeks after the last dose of apitegromab Exclusion Criteria: * Patient permanently discontinued study treatment during the feeder trial (i.e., TOPAZ or SAPPHIRE) * Nutritional status that was not stable over the past 6 months and is not anticipated to be stable throughout the trial or medical necessity for a gastric/nasogastric feeding tube, where the majority of feeds are given by this route, as assessed by the Investigator * Patient is currently enrolled in any investigational drug trial other than TOPAZ or SAPPHIRE * Prior history of severe hypersensitivity reaction or intolerance to SMN-targeted therapies * Prior history of severe hypersensitivity reaction or intolerance to apitegromab * Use of chronic daytime noninvasive ventilatory support for \>16 hours daily in the 2 weeks before dosing, or anticipated to regularly receive such daytime ventilator support chronically throughout the trial * Any acute or comorbid condition interfering with the well-being of the patient at the patient's last visit in TOPAZ or SAPPHIRE, (including active systemic infection, the need for acute treatment, or inpatient observation due to any reason). After resolution of the condition, the patient can be enrolled in the trial if they meet all the other eligibility criteria. * Pregnant or breastfeeding * Any other condition or clinically significant laboratory result or ECG value that, in the opinion of the Investigator, may compromise safety or compliance, would preclude the patient from successful completion of the trial, or interfere with the interpretation of the results

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Conditions

The condition(s) this trial relates to.

Atrophy muscular atrophy neuromuscular disease Neuromuscular Manifestations proximal spinal muscular atrophy Spinal Muscular Atrophies of Childhood spinal muscular atrophy spinal muscular atrophy, type II spinal muscular atrophy, type III

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

Anti-myostatin Atrophy Muscular atrophy Muscular atrophy, spinal Neuromuscular diseases Neuromuscular manifestations SMA Spinal muscular atrophy Spinal muscular atrophy type 2 Spinal muscular atrophy type 3

Contacts and locations

Locations

  • Boston Children's Hospital

    Boston, Massachusetts, 02115, United States

  • CHR Citadelle

    Liège, 4000, Belgium

  • CHRU de Lille - Hpital Jeanne de Flandre

    Lille, 59037, France

  • CHU Toulouse Hopital des Enfants

    Toulouse, 31059, France

  • Carlo Besta Neurological Research Institute

    Milan, 20133, Italy

  • Children's Hospital Colorado

    Aurora, Colorado, 80045, United States

  • Children's Hospital Los Angeles

    Los Angeles, California, 90027, United States

  • Children's Specialty Group PLLC (Children's Hospital of The King's Daughters)

    Newport News, Virginia, 23606, United States

  • Columbia University Medical Center

    New York, New York, 10032, United States

  • Fondazione Policlinico Universitario A. Gemelli

    Roma, 106, Italy

  • Gillette Children's Specialty Healthcare

    Saint Paul, Minnesota, 55101, United States

  • Great Ormond Street Hospital for Children

    London, WC1N 1EH, United Kingdom

  • Helen DeVos Children's Hospital

    Grand Rapids, Michigan, 49503, United States

  • Hopital Trousseau - I-Motion

    Paris, 75012, France

  • Hospital Sant Joan de Deau

    Barcelona, 08950, Spain

  • Hospital Universitari i Politecnic La Fe

    Valencia, 46026, Spain

  • Instytut Pomnik - Centrum Zdrowia Dziecka

    Warsaw, 04-730, Poland

  • Istituto Giannina Gaslini, Centro Traslazionale di Miologia e Patologie Neurodegenerative

    Genova, 16147, Italy

  • Johns Hopkins Hospital

    Baltimore, Maryland, 21287, United States

  • Klinikum der Universitat Munchen, Dr. von Haunersches Kinderspital, Abteilung fur Kinderneurologie und Entwicklungsneurologie

    Munchen, Bayern, 80337, Germany

  • Leeds Children's Hospital Clinical Research

    Leeds, LS1 3EX, United Kingdom

  • Lurie Children's Hospital of Chicago

    Chicago, Illinois, 60611, United States

  • Nationwide Children's Hospital

    Columbus, Ohio, 43215, United States

  • Nemours Biomedical Research

    Orlando, Florida, 32827, United States

  • NeuroMuscular Omnicentre

    Milan, 20162, Italy

  • Oregon Health & Science University

    Portland, Oregon, 97239, United States

  • Phoenix Childrens Hospital

    Phoenix, Arizona, 85016, United States

  • Seattle Children's Hospital

    Seattle, Washington, 98115, United States

  • St. Jude Children's Research Hospital

    Memphis, Tennessee, 38105, United States

  • Stanford Neuroscience Health Center

    Palo Alto, California, 94304, United States

  • The Children's Hospital of Philadelphia

    Philadelphia, Pennsylvania, 19104, United States

  • UCSD Altman Clinical and Translational Research

    La Jolla, California, 92037, United States

  • UMC Utrecht

    Utrecht, 3508, Netherlands

  • UOC NEUROLOGIA E MALATTIE NEUROMUSCOLARI A.O.U Policlinico G. Martino

    Messina, 98125, Italy

  • UZ Gent

    Ghent, 9000, Belgium

  • UZ Leuven

    Leuven, 3000, Belgium

  • Universitatsklinikum Essen

    Essen, 45147, Germany

  • Universitatsklinikum Freiburg

    Freiburg im Breisgau, 79106, Germany

  • University of Iowa

    Iowa City, Iowa, 52242, United States

  • University of Kansas Medical Center

    Fairway, Kansas, 66205, United States

  • University of Oxford

    Oxford, OX3 0ER, United Kingdom

  • University of Texas Southwestern - Pediatric Neurology

    Dallas, Texas, 75207, United States

  • University of Utah

    Salt Lake City, Utah, 84112, United States

  • University of Wisconsin Hospital

    Madison, Wisconsin, 53792, United States

  • Universitätskinderklinik Bonn, Abteilung für Neuropädiatrie und SPZ

    Bonn, 53127, Germany

  • Uniwersytecki Szpital Kliniczny w Poznaniu, Oddział Kliniczny Neurologii Dzieci i Młodzieży

    Poznan, 60-355, Poland

  • Uniwersyteckie Centrum Kliniczne

    Gdansk, 80-211, Poland

  • Wake Forest University School of Medicine

    Winston-Salem, North Carolina, 27157, United States

  • Washington University Medical Campus

    St Louis, Missouri, 63110, United States

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