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NCT Number: NCT07047144

A Study to Evaluate How Apitegromab Works in Subjects Who Are Less Than 2 Years Old and Have Spinal Muscular Atrophy

This double-blind, Phase 2, multiple-dose study will be conducted to evaluate the PK/PD, efficacy, safety, and tolerability of apitegromab in subjects <2 years old with 5q autosomal recessive SMA who have delayed motor milestones for their age attributed to SMA at the discretion of the Investigator or a Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) score <55.

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Key information

Conditions

Spinal Muscular Atrophy Anti-myostatin Central Nervous System Diseases Congenital, Hereditary, and Neonatal Diseases and Abnormalities Genetic Diseases, Inborn Heredodegenerative Disorders, Nervous System Motor Neuron Disease Muscular Atrophy, Spinal Nervous System Diseases Neurodegenerative Diseases Neurologic Manifestations Neuromuscular Diseases Neuromuscular Manifestations Pathological Conditions, Signs and Symptoms SMA Signs and Symptoms Spinal Cord Diseases Spinal Muscular Atrophies of Childhood Spinal Muscular Atrophy Type 2 Spinal Muscular Atrophy Type 3

Age range

Up to 2 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 2

Primary location

UZ Gent, Ghent, East-Flanders, Belgium

Loading trial locations.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Is <2 years old at the time of the informed consent
  • Had a gestational age of ≥35 weeks and gestational body weight ≥2.0 kg at birth
  • Has confirmed diagnosis of 5q autosomal recessive SMA
  • Has confirmed presence of SMN2 gene copy(ies)
  • Must have been treated with an approved SMN1-targeted therapy (ie, onasemnogene abeparvovec-xioi) or are continuing to be treated with an approved SMN2-targeted therapy (ie, nusinersen or risdiplam)
  • Body weight for age is no less than 1st percentile based on the WHO Child Growth Standards at the Screening Visit
  • Has delayed motor milestones for age attributed to SMA at the discretion of the Investigator or a CHOP-INTEND score <55

Exclusion criteria

  • Nutritional status that is not anticipated to be stable throughout the study or medical necessity for a gastric feeding tube, where most feeds are administered by this route
  • Major orthopedic issues such as severe scoliosis or severe contractures or interventional procedure, including spine or hip surgery, which is considered to have the potential to substantially limit the ability of the subject to be evaluated on any motor function outcome measures, within 6 months before Screening or anticipated during the study
  • Any other physical limitations (eg, the subject requires cast for contractures) that would prevent the subject from undergoing motor function outcome measures throughout the study.

Treatment and study plan

Apitegromab

Drug

Apitegromab is a fully human anti-proMyostatin monoclonal antibody (mAb) of the immunoglobulin G4 (IgG4)/lambda isotype that specifically binds to human pro/latent myostatin with high affinity inhibiting myostatin activation. SRK-015 will be administered every 4 weeks by intravenous (IV) infusion.

Other names: SRK-015

nusinersen

Drug

Nusinersen is a current standard-of-care SMN therapy that targets the SMN2 gene. It will be administered intrathecally per the prescribing information.

Other names: Spinraza

Risdiplam

Drug

Risdiplam is a current standard-of-care SMN therapy that targets the SMN2 gene. It will be administered orally per the prescribing information.

Other names: Evrysdi

Primary outcomes

  1. Evaluate the PK of apitegromab in subjects <2 years old with SMA

    Time frame: 52 Weeks

    Apitegromab concentrations in serum

  2. Evaluate the PD of apitegromab in subjects <2 years old with SMA

    Time frame: 52 Weeks

    Total latent myostatin concentrations in serum

  3. Evaluate the motor function outcomes (ie, efficacy) due to apitegromab treatment

    Time frame: 48 Weeks

    Change from baseline in the raw score of the Bayley Scale of Infant and Toddler Development, Fourth Edition - Gross Motor Subscale (BSID-4 GMS) at 48 weeks. BSID-4 GMS is a standardized assessment commonly used to evaluate development across 5 domains in infants and young children. It consists of 58 items, scored from 0 to 2 for each item, with higher scores indicating better gross motor development.

Secondary outcomes

  1. Assess the safety and tolerability of apitegromab administered to subjects receiving an SMN therapy

    Time frame: 52 Weeks

    Incidence of TEAEs and SAEs by severity

Study contacts

Contact information is provided by the study sponsor or research team.

Scholar Rock

CONTACT

[email protected]

857-259-3860

Sponsors and collaborators

Lead sponsor

Scholar Rock, Inc.

Industry

Registry information

Official study title

A Phase 2, Double-Blind Study to Evaluate the Pharmacokinetics, Pharmacodynamics, Efficacy, and Safety of Apitegromab in Subjects <2 Years Old With Spinal Muscular Atrophy (SMA)

Acronym: OPAL

Important dates

Study start
2025
Primary completion
2028
Study completion
2029
First posted
Jul 2, 2025
Registry last updated
May 1, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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