A Study to Evaluate How Apitegromab Works in Subjects Who Are Less Than 2 Years Old and Have Spinal Muscular Atrophy
OPAL
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)
1 other identifier
interventional
52
7 countries
25
Brief Summary
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.
Trial Health
Trial Health Score
Automated assessment based on enrollment pace, timeline, and geographic reach
participants targeted
Target at P25-P50 for phase_2
Started Sep 2025
Typical duration for phase_2
25 active sites
Health score is calculated from publicly available data and should be used for screening purposes only.
Trial Relationships
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Study Timeline
Key milestones and dates
First Submitted
Initial submission to the registry
April 16, 2025
CompletedFirst Posted
Study publicly available on registry
July 2, 2025
CompletedStudy Start
First participant enrolled
September 15, 2025
CompletedPrimary Completion
Last participant's last visit for primary outcome
November 1, 2028
ExpectedStudy Completion
Last participant's last visit for all outcomes
March 1, 2029
May 1, 2026
April 1, 2026
3.1 years
April 16, 2025
April 29, 2026
Conditions
Outcome Measures
Primary Outcomes (3)
Evaluate the PK of apitegromab in subjects <2 years old with SMA
Apitegromab concentrations in serum
52 Weeks
Evaluate the PD of apitegromab in subjects <2 years old with SMA
Total latent myostatin concentrations in serum
52 Weeks
Evaluate the motor function outcomes (ie, efficacy) due to apitegromab treatment
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.
48 Weeks
Secondary Outcomes (1)
Assess the safety and tolerability of apitegromab administered to subjects receiving an SMN therapy
52 Weeks
Study Arms (2)
Apitegromab low dose + SMN Therapy
EXPERIMENTALPatients who are less than 2 years of age with SMA will receive apitegromab every 4 weeks by intravenous (IV) infusion during the 48-week Treatment Period. Patients 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).
Apitegromab high dose + SMN Therapy
EXPERIMENTALPatients who are less than 2 years of age with SMA will receive apitegromab every 4 weeks by intravenous (IV) infusion during the 48-week Treatment Period. Patients 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).
Interventions
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.
Nusinersen is a current standard-of-care SMN therapy that targets the SMN2 gene. It will be administered intrathecally per the prescribing information.
Risdiplam is a current standard-of-care SMN therapy that targets the SMN2 gene. It will be administered orally per the prescribing information.
Eligibility Criteria
You may qualify if:
- 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
You may not qualify if:
- 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.
Contact the study team to confirm eligibility.
Sponsors & Collaborators
Study Sites (25)
Phoenix Children's Hospital
Phoenix, Arizona, 85016, United States
Children's Hospital of Orange County (CHOC)
Orange, California, 92868, United States
Stanford Neuroscience Health Center (SNHC)
Palo Alto, California, 94304, United States
Children's Hospital Colorado
Aurora, Colorado, 80045, United States
Children's Healthcare of Atlanta
Atlanta, Georgia, 30329, United States
University of Iowa
Iowa City, Iowa, 52242, United States
Helen DeVos Children's Hospital at Spectrum Health
Grand Rapids, Michigan, 49503, United States
Atrium Health Wake Forest Baptist
Winston-Salem, North Carolina, 27157, United States
The Children's Hospital of Philadelphia
Philadelphia, Pennsylvania, 19104, United States
Le Bonheur Children's Hospital
Memphis, Tennessee, 38103, United States
University of Texas Southwestern Medical Center
Dallas, Texas, 75207, United States
Neurology Rare Disease Center
Flower Mound, Texas, 75028, United States
Cook Children's Medical Center
Fort Worth, Texas, 76104, United States
Texas Children's Hospital (TCH)-Clinical Care Center (CCC)
Houston, Texas, 77030, United States
UZ Gent
Ghent, East-Flanders, 9000, Belgium
UZ Leuven - Campus Gasthuisberg
Leuven, 3000, Belgium
CHR Citadelle
Liège, 4000, Belgium
Hopital Trousseau - I-Motion
Paris, 75012, France
Fondazione I.R.C.C.S. - Istituto Neurologico Carlo Besta
Milan, 20133, Italy
Centro Clinico NeMO Milano - Fondazione Serena Onlus
Milan, 20162, Italy
Fondazione Policlinico Universitario Agostino Gemelli IRCCS
Rome, 00168, Italy
Universitair Medisch Centrum Utrecht
Utrecht, 3584 CX, Netherlands
Hospital Sant Joan de Déu Barcelona
Barcelona, 08950, Spain
Hospital Universitari i Politecnico La Fecnic La Fe
Valencia, 46026, Spain
Leeds General Infirmary Children's Research Department
Leeds, West Yorkshire, LS1 3EX, United Kingdom
MeSH Terms
Conditions
Interventions
Condition Hierarchy (Ancestors)
Central Study Contacts
Study Design
- Study Type
- interventional
- Phase
- phase 2
- Allocation
- RANDOMIZED
- Masking
- QUADRUPLE
- Who Masked
- PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
- Masking Details
- The Sponsor, the subject's caregiver, Investigators, and site personnel, with the exception of the designated unblinded personnel (eg, site Pharmacist), will be blinded to the treatment assignment.
- Purpose
- TREATMENT
- Intervention Model
- PARALLEL
- Sponsor Type
- INDUSTRY
- Responsible Party
- SPONSOR
- Expanded Access
- Yes
Study Record Dates
First Submitted
April 16, 2025
First Posted
July 2, 2025
Study Start
September 15, 2025
Primary Completion (Estimated)
November 1, 2028
Study Completion (Estimated)
March 1, 2029
Last Updated
May 1, 2026
Record last verified: 2026-04
Data Sharing
- IPD Sharing
- Will not share