A Phase 3 interventional study of Apitegromab in Spinal Muscular Atrophy, Spinal Muscular Atrophy Type 3 and Spinal Muscular Atrophy Type 2, sponsored by Scholar Rock, Inc.. Active, not recruiting at 49 sites in 9 countries. Open to participants aged 2 Years and older. Per ClinicalTrials.gov, last updated 2026-09-01.
Sponsored by Scholar Rock, Inc. · Phase 3, Interventional, and Treatment
The ONYX study is an Open-Label, Multicenter, Extension study that will evaluate the long-term safety and efficacy of Apitegromab in Patients with Type 2 and Type 3 SMA who have completed TOPAZ or SAPPHIRE.
61 studies on the registry are indexed under Spinal Muscular Atrophies of Childhood; 18 are open to participants now.
This study's enrollment of 238 is above the median of 15 across 41 interventional studies indexed under Spinal Muscular Atrophies of Childhood.
Browse Spinal Muscular Atrophies of Childhood studies →Scholar Rock, Inc. is the lead sponsor of 9 studies on the registry; 3 are open to participants now.
Compared within Spinal Muscular Atrophies of Childhood, this study's primary condition as ClinicalTrials.gg classifies it; the registry's first condition term is Muscular Atrophy, Spinal. The counts are of registry records indexed under each term, refreshed daily. How we classify →
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Life expectancy
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECG (electrocardiogram)
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Patients who are ≥2 years of age with Type 2 and Type 3 SMA will receive apitegromab 20 mg/kg every 4 weeks by intravenous (IV) infusion during the 104-week Treatment Period
Drug: Apitegromab
Apitegromab (SRK-015) is an investigational, fully human immunoglobulin G4 monoclonal antibody that specifically binds to human proforms (i.e., inactive precursor forms) of myostatin, pro- and latent- myostatin, with high affinity, inhibiting activation of myostatin, a negative regulator of muscle growth and strength.
Evaluate the long-term safety and tolerability of apitegromab in patients with Type 2 and Type 3 SMA
Incidence of TEAEs and SAEs by severity
Time frame: Up to 6 years
Evaluate the long-term efficacy of apitegromab by assessing changes in motor function outcome measures at prespecified time points
Hammersmith Functional Motor Scale Expanded (HFMSE) total score at prespecified time points (excludes ambulatory patients)
Time frame: Up to 6 years
Evaluate the long-term efficacy of apitegromab by assessing changes in motor function outcome measures at prespecified time points
Revised Upper Limb Module (RULM) total score at prespecified time points (excludes ambulatory patients)
Time frame: Up to 6 years
Evaluate the long-term efficacy of apitegromab by assessing changes in motor function outcome measures at prespecified time points
Number of World Health Organization (WHO) motor development milestones attained at prespecified time points (excludes ambulatory patients)
Time frame: Up to 6 years
Evaluate the long-term efficacy of apitegromab by assessing changes in motor function outcome measures at prespecified time points
Revised Hammersmith Scale (RHS) total score
Time frame: Up to 6 years
Evaluate the long-term efficacy of apitegromab by assessing changes in motor function outcome measures at prespecified time points
Results for 6-Minute Walk Test
Time frame: Up to 6 years
Evaluate the long-term efficacy of apitegromab by assessing changes in motor function outcome measures at prespecified time points
30-Second Sit-to-Stand
Time frame: Up to 6 years
Further evaluate the immunogenicity of apitegromab
Presence or absence of antidrug antibody (ADA) against apitegromab in serum from blood samples
Time frame: Up to 6 years
Further characterize the PK of apitegromab
Apitegromab concentrations in serum from blood samples at prespecified time points
Time frame: Up to 6 years
Further evaluate the pharmacodynamic (PD) effects of apitegromab
Total latent myostatin concentrations in blood samples at prespecified time points
Time frame: Up to 6 years
To further evaluate the effect of apitegromab on patient/caregiver-reported disability, and fatigability.
Pediatric Evaluation of Disability Inventory Computer Adaptive Test (PEDI-CAT) at prespecified time points
Time frame: Up to 6 years
To further evaluate the effect of apitegromab on patient/caregiver-reported disability, and fatigability.
Patient-reported Outcomes Measurement Information System (PROMIS) Fatigue Questionnaire at prespecified time points
Time frame: Up to 6 years
To further evaluate the effect of apitegromab on patient/caregiver-reported disability, and fatigability.
Assessment of Caregiver Experience with Neuromuscular Disease (ACEND) at prespecified time points
Time frame: Up to 6 years
Plan to share: No
No publications or documents are linked to this record.
This study is active, not recruiting, as verified in Aug 2026. You cannot join it, but the record below documents what was studied.
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Studies of the drug tested here: Apitegromab
Spinal Muscular Atrophies of Childhood →
Scholar Rock, Inc.