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Study on Long-Term Safety and Effects of Apitegromab in Patients with Type 2 and Type 3 Spinal Muscular Atrophy Who Completed Previous Trials

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying the long-term safety and effectiveness of a treatment called apitegromab in patients with Spinal Muscular Atrophy (SMA). SMA is a genetic condition that leads to muscle weakness and shrinking. The study specifically involves patients with Type 2 and Type 3 SMA who have already participated in previous trials of apitegromab. Apitegromab is administered as an infusion, which means it is given directly into the bloodstream through a vein.

The purpose of this study is to evaluate how well patients tolerate apitegromab over an extended period. Participants will receive regular infusions of the medication and will be monitored for any side effects or changes in their condition. The study will track various health measures to understand the impact of the treatment on muscle function and overall health. Some participants may receive a placebo, which is a substance with no active medication, to compare the effects of apitegromab.

Throughout the study, participants will have regular check-ups and assessments to ensure their safety and to gather information on how the treatment is working. The study aims to provide valuable insights into the long-term use of apitegromab for managing SMA, helping to improve future treatment options for individuals with this condition.

The research process

The trial runs in 4 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Joining the trial

    Participation begins after completing a previous trial of apitegromab.

    Eligibility requires signing an informed consent document. If underage, a parent or guardian must sign, and assent from the patient is needed.

    A life expectancy of more than two years from the start of the trial is required.

    Ability to receive drug infusions and provide blood samples through an IV is necessary.

    Adherence to the trial protocol is mandatory.

    Females of childbearing potential must have a negative pregnancy test at the start and use contraception during the trial and for 20 weeks after the last dose.

  2. Step 2

    Treatment administration

    Apitegromab is administered through an intravenous infusion.

    The frequency and dosage are determined by the trial protocol and medical team.

  3. Step 3

    Monitoring and assessments

    Regular monitoring for any treatment-emergent adverse events (TEAEs) and serious adverse events (SAEs) is conducted.

    Assessments include measuring motor function scores at specific time points, such as HFMSE, RULM, and RHS scores, depending on the cohort.

  4. Step 4

    Completion of the trial

    The trial is estimated to end by August 12, 2027.

    Final assessments and evaluations are conducted to determine the long-term safety and efficacy of apitegromab.

Who can join the trial?

6 criteria

  • The patient or their parent/legal guardian must sign a document agreeing to participate in the study. If the patient is a minor, they must also agree orally or in writing, if required.
  • The patient must have completed a previous study called Phase 2 TOPAZ or Phase 3 SAPPHIRE.
  • The patient should have an estimated life expectancy of more than 2 years from the start of the study.
  • The patient must be able to receive the study drug through an IV (a tube that goes into a vein) and give blood samples using an IV that is already in place for other medical reasons.
  • The patient must be able to follow the study's rules and requirements.
  • Females who can have children must have a negative pregnancy test at the start and agree to use at least one method of birth control during the study and for 20 weeks after the last dose of the study drug.
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Investigated drugs

Apitegromab is a medication being studied for its long-term safety and effectiveness in patients with Type 2 and Type 3 Spinal Muscular Atrophy (SMA). It is designed to help improve muscle strength and function in individuals affected by this condition. The trial aims to assess how well patients tolerate the medication over an extended period.

What is already known about the treatment

Apitegromab – Apitegromab is administered as an intravenous infusion, meaning it is delivered directly into the bloodstream through a vein. It is currently being studied in clinical trials for its long-term safety and effectiveness in treating patients with Type 2 and Type 3 Spinal Muscular Atrophy (SMA). The main therapeutic indication for apitegromab is to improve muscle function in individuals with SMA. At the molecular level, apitegromab works by inhibiting a protein called myostatin, which is known to limit muscle growth, thereby potentially enhancing muscle strength and function. It is classified pharmacologically as a myostatin inhibitor.

Investigated diseases

Spinal Muscular Atrophy (SMA) – Spinal Muscular Atrophy is a genetic disorder characterized by weakness and wasting of the muscles used for movement. It is caused by the loss of specialized nerve cells, called motor neurons, in the spinal cord and the part of the brain connected to the spinal cord. This leads to progressive muscle weakness and atrophy, primarily affecting the muscles closest to the center of the body. SMA is classified into different types based on the age of onset and severity of symptoms, with Type 2 and Type 3 being less severe than Type 1. Individuals with Type 2 SMA typically develop symptoms between 6 and 18 months of age, while those with Type 3 may not show symptoms until after 18 months. The progression of muscle weakness can vary, but it generally leads to difficulties with movement and mobility.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-511654-42-00Protocol codeSRK-015-004Estimated enrolment236 patientsSponsorScholar Rock Inc.

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On this site, “treatment” means an investigational medicine being studied in a clinical trial. Its safety and efficacy for the use being studied have not yet been confirmed, some participants may receive a placebo or a comparator medicine, and taking part does not guarantee any health benefit. The decision to take part is made by the doctor at the research site. This site is for information only and does not replace medical advice.

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