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An Active Treatment Study of SRK-015 in Patients With Type 2 or Type 3 Spinal Muscular Atrophy

Phase 2 Active Treatment Study to Evaluate the Efficacy and Safety of SRK-015 in Patients With Later-Onset Spinal Muscular Atrophy (TOPAZ)

Status
Completed
Phases
Phase 2
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT03921528
Acronym
TOPAZ
Enrollment
58
Registered
2019-04-19
Start date
2019-04-22
Completion date
2024-02-28
Last updated
2024-12-02

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Atrophy, Muscular Atrophy, Muscular Atrophy, Spinal, Neuromuscular Diseases, Neuromuscular Manifestations, SMA, Spinal Muscular Atrophy, Spinal Muscular Atrophy Type 2, Spinal Muscular Atrophy Type 3

Brief summary

The TOPAZ study will assess the safety and efficacy of SRK-015 in later-onset Spinal Muscular Atrophy (SMA Type 2 and Type 3) in pediatric and adult patients.

Interventions

BIOLOGICALSRK-015

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

Sponsors

Scholar Rock, Inc.
Lead SponsorINDUSTRY

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE

Masking description

Active treatment, randomized, double-blind for Cohort 3

Eligibility

Sex/Gender
ALL
Age
2 Years to 21 Years
Healthy volunteers
No

Inclusion criteria

* Age 5 through 21 years old at the time of screening for Cohorts 1 and 2; Age ≥2 years old at the time of screening for Cohort 3. * Documented diagnosis of 5q SMA. * Diagnosed as later-onset (e.g., Type 2 or Type 3) SMA prior to receiving any treatment with therapy approved for SMA. * Non-ambulatory patients must be able to sit independently (sits up straight with head erect for at least 10 seconds; does not use arms or hands to balance body or support position) per World Health Organization (WHO) motor milestones definition at screening. * Ambulatory patients must have the ability to independently ambulate without aids or orthotics over 10 meters in 30 seconds or less at screening. * Receiving the same background SMA therapy (e.g., on an approved survival motor neuron (SMN) upregulator therapy such as nusinersen, or not on any SMA therapy) for at least 6 months prior to screening and anticipated to remain on that therapy throughout the duration of the study. * If receiving the SMN upregulator therapy nusinersen, must have completed the loading regimen and initiated maintenance dosing (i.e., completed at least one maintenance dose) with at least 4 weeks after the first maintenance dose having elapsed prior to screening. * Nutritional status stable over the past 6 months and anticipated to be stable throughout the duration of the study. * Have no physical limitations that would prevent the patient from undergoing motor function outcome measures throughout the duration of the study. * Able to receive study drug infusions and provide blood samples through the use of a peripheral intravenous (IV) or a long-term IV access device that the patient has placed for reasons independent from the study throughout the duration of the study. * Able to adhere to the requirements of the protocol, including travel to the study center and completing all study procedures and study visits. * For patients who are expected to have reached reproductive maturity by the end of the study, adhere to study specific contraception requirements.

Exclusion criteria

* Use of tracheostomy with positive pressure. * Use of chronic daytime non-invasive ventilatory support for \>16 hours daily in the 2 weeks prior to dosing, or anticipated to regularly receive such daytime ventilator support chronically over the duration of the study. * Any acute or co-morbid condition interfering with the well-being of the patient within 14 days of screening, including active systemic infection, the need for acute treatment or inpatient observation due to any reason. * Severe scoliosis and/or contractures at screening. Based on clinical judgement, any scoliosis or contractures present must be stable over the past 6 months, anticipated to be stable for the duration of the study and not prevent the patient from being evaluated on any functional outcome measures throughout the duration of the study. * Pregnant or breastfeeding. * Major orthopedic or other interventional procedure, including spine or hip surgery, considered to have the potential to substantially limit the ability of the patient to be evaluated on any functional outcome measures, within 6 months prior to screening, or anticipated for the duration of the study. * Prior history of a hypersensitivity reaction to a monoclonal antibody (mAb) or recombinant protein bearing an Fc domain (such as a soluble receptor- Fc fusion protein). * Use of systemic corticosteroids within 60 days prior to screening. Inhaled or topical steroids are allowed. * Treatment with investigational drugs within 3 months prior to screening. * Use of therapies with potentially significant muscle effects (such as androgens, insulin-like growth factor, growth hormone, systemic betaagonist, botulinum toxin, or muscle relaxants) or muscle-enhancing supplements within 60 days prior to screening. * Patient has any other condition, which in the opinion of the Investigator may compromise safety or compliance, would preclude the patient from successful completion of the study, or interfere with the interpretation of the results.

Design outcomes

Primary

MeasureTime frameDescription
Cohort 1: Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Day 364 (Visit 15) [Month 12]Baseline up to 12 monthsThe Revised Hammersmith Scale (RHS) is a 36 item clinical assessment of physical abilities in patients with Type 2 SMA and ambulatory or nonambulatory patients with Type 3 SMA. For the ambulatory Type 3 patients 5-21 years of age in Cohort 1 (N=23), the primary endpoint was the change from baseline in RHS total score at month 12. The RHS has a minimum achievable score of 0 and a maximum achievable score of 69. The RHS includes 33 items that are graded on a scale of 0, 1, 2, where 0 denotes the lowest level and 2 denotes the highest level of ability/function. The remaining 3 items are scored 0 or 1, where 0 denotes an inability and 1 denotes an ability to achieve. Higher scores indicate increased motor function. A positive change from Baseline indicates improvement.
Cohort 2 and Cohort 3: Change From Baseline in Hammersmith Functional Motor Scale Expanded (HFMSE) Total Score at Day 364 (Visit 15) [Month 12]Baseline up to 12 monthsCohort 2: For the nonambulatory Type 2 and Type 3 patients 5-21 years of age in Cohort 2 (N=15), the primary efficacy endpoint was the change from baseline in HFMSE total score at month 12. Cohort 3: For the nonambulatory Type 2 patients ≥2 years of age in Cohort 3 (N=20), the primary efficacy endpoint was the change from baseline in HFMSE total score at month 12. The Hammersmith Functional Motor Scale Expanded (HFMSE) assesses the physical abilities of patients with Type 2 and Type 3 SMA comprises 33 items graded on a scale of 0, 1, or 2, where 0 denotes unable, 1 denotes performed with modification or adaptation, and 2 denotes performed without modification or adaptation.

Secondary

MeasureTime frameDescription
Cohort 1: Change From Baseline in 6-Minute Walk Test (6MWT)Baseline to 12 months6-Minute Walk Test The 6-Minute Walk Test (6MWT) is an assessment of exercise capacity and fatigue used for ambulatory patients with later-onset SMA who are directed to walk along a 25 meter course as fast as possible over 6 minutes.
Cohort 1: Change From Baseline in 30-Second Sit-to-StandBaseline to 12 monthsThe 30-Second Sit-to-Stand Test is an assessment of functional lower-limb strength that measures the maximal number of times a patient can transition from sitting to standing in 30 seconds.
Cohort 1: Change From Baseline in 10-Meter Walk/Run (From RHS)Baseline to 12 monthsThe 10 Meter Walk/Run test is an enhanced function of the RHS used for ambulatory patients with Type 3 SMA. It is a measure of the time taken to walk/run 10 meters. The time to perform is summarized only for patients able to complete the RHS 10-meter walk/run item.
Cohort 1: Change From Baseline in Timed Rise From Floor (From RHS)Baseline to 12 monthsThe timed rise from floor test is an enhanced function of the RHS used for ambulatory patients with Type 3 SMA. It is a measure of the time taken to rise to standing from the floor. The time to rise from floor is summarized only for patients able to complete the RHS rise from floor item.
Cohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified TimepointsBaseline to 12 monthsThe Revised Hammersmith Scale (RHS) is a 36 item clinical assessment of physical abilities in patients with Type 2 SMA and ambulatory or nonambulatory patients with Type 3 SMA; it has a maximum achievable score of 69. The RHS includes 33 items that are graded on a scale of 0, 1, 2, where 0 denotes the lowest level and 2 denotes the highest level of ability/function. The remaining 3 items are scored 0 or 1, where 0 denotes an inability and 1 denotes an ability to achieve.
Cohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in HFMSE Score From BaselineBaseline to 12 monthsThe Hammersmith Functional Motor Scale Expanded (HFMSE) assesses the physical abilities of patients with Type 2 and Type 3 SMA comprises 33 items graded on a scale of 0, 1, or 2, where 0 denotes unable, 1 denotes performed with modification or adaptation, and 2 denotes performed without modification or adaptation.
Cohort 2 & 3: Change in Baseline in Revised Upper Limb Module (RULM) Total ScoreBaseline to 12 monthsThe RULM is a 20 item assessment of upper limb function in nonambulatory patients with SMA that was performed for patients who were 30 months of age or older at baseline. The 19 scored items assess functions that relate to everyday life, such as pressing a button and picking up a token; these items are scored 0, 1, or 2, where 0 denotes unable, 1 denotes able with modification, and 2 denotes able with no modification. The maximum score achievable is 37.
Cohort 2 & 3: Proportion of Patients Achieving a New WHO Motor Development Milestones Relative to BaselineBaseline to 12 monthsThe WHO Multicenter Growth Reference Study performance criteria is being utilized to assess the World Health Organization (WHO) motor development milestones of patients with Type 2 and nonambulatory Type 3 SMA enrolled in Cohort 2 and Cohort 3 relative to baseline. The WHO milestone assessment consists of six items which were selected because they have been considered to be universal, fundamental, and simple to test and evaluate, they include 1) sitting without support, 2) hands and knees crawling, 3) standing with assistance, 4) walking with assistance, 5) standing alone, and 6) walking without assistance. Each item is recorded as 1 (unable), 2 (refusal), 3 (Yes) or 9 (did not test). The number of 3s was counted as the final score. The minimum was 0, which means no motor milestones were achieved; the maximum was 6, which means all 6 milestones were achieved.
Cohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in RULM Score From BaselineBaseline to 12 monthsThe RULM is a 20 item assessment of upper limb function in nonambulatory patients with SMA that was performed for patients who were 30 months of age or older at baseline. The 19 scored items assess functions that relate to everyday life, such as pressing a button and picking up a token; these items are scored 0, 1, or 2, where 0 denotes unable, 1 denotes able with modification, and 2 denotes able with no modification. The maximum score achievable is 37.
Cohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsBaseline to 12 monthsThe Hammersmith Functional Motor Scale Expanded (HFMSE) assesses the physical abilities of patients with Type 2 and Type 3 SMA comprises 33 items graded on a scale of 0, 1, or 2, where 0 denotes unable, 1 denotes performed with modification or adaptation, and 2 denotes performed without modification or adaptation.
Cohort 1: Proportion of Patients Achieving Various Magnitudes of Change in RHS Score From BaselineBaseline to 12 monthsThe Revised Hammersmith Scale (RHS) is a 36 item clinical assessment of physical abilities in patients with Type 2 SMA and ambulatory or nonambulatory patients with Type 3 SMA; it has a maximum achievable score of 69. The RHS includes 33 items that are graded on a scale of 0, 1, 2, where 0 denotes the lowest level and 2 denotes the highest level of ability/function. The remaining 3 items are scored 0 or 1, where 0 denotes an inability and 1 denotes an ability to achieve.

Countries

Italy, Netherlands, Spain, United States

Participant flow

Participants by arm

ArmCount
Cohort 1 - Monotherapy
Ambulatory Type 3 SMA apitegromab (SRK-015) 20mg/kg SRK-015: SRK-015 is a fully human anti-proMyostatin monoclonal antibody (mAb) of the immunoglobulin G4 (IgG4)/lambda isotype that binds to human pro/latent myostatin with high affinity. SRK-015 was administered every 4 weeks by intravenous infusion.
11
Cohort 1 - Dual Therapy
Ambulatory Type 3 SMA apitegromab (SRK-015) 20mg/kg + nusinersen SRK-015: SRK-015 is a fully human anti-proMyostatin monoclonal antibody (mAb) of the immunoglobulin G4 (IgG4)/lambda isotype that binds to human pro/latent myostatin with high affinity. SRK-015 was administered every 4 weeks by intravenous infusion.
12
Cohort 2
Type 2 SMA / Non-Ambulatory Type 3 SMA apitegromab (SRK-015) 20 mg/kg + nusinersen SRK-015: SRK-015 is a fully human anti-proMyostatin monoclonal antibody (mAb) of the immunoglobulin G4 (IgG4)/lambda isotype that binds to human pro/latent myostatin with high affinity. SRK-015 was administered every 4 weeks by intravenous infusion.
15
Cohort 3 - Low Dose
Type 2 SMA apitegromab (SRK-015) 2 mg/kg + nusinersen SRK-015: SRK-015 is a fully human anti-proMyostatin monoclonal antibody (mAb) of the immunoglobulin G4 (IgG4)/lambda isotype that binds to human pro/latent myostatin with high affinity. SRK-015 was administered every 4 weeks by intravenous infusion.
10
Cohort 3 - High Dose
Type 2 SMA apitegromab (SRK-015) 20mg/kg + nusinersen SRK-015: SRK-015 is a fully human anti-proMyostatin monoclonal antibody (mAb) of the immunoglobulin G4 (IgG4)/lambda isotype that binds to human pro/latent myostatin with high affinity. SRK-015 was administered every 4 weeks by intravenous infusion.
10
Total58

Baseline characteristics

CharacteristicCohort 1 - MonotherapyCohort 1 - Dual TherapyCohort 2Cohort 3 - Low DoseCohort 3 - High DoseTotal
Age, Continuous12.1 Years13.1 Years11.7 Years4.1 Years3.8 Years9.67 Years
Ethnicity (NIH/OMB)
Hispanic or Latino
0 Participants2 Participants2 Participants0 Participants1 Participants5 Participants
Ethnicity (NIH/OMB)
Not Hispanic or Latino
11 Participants10 Participants13 Participants10 Participants9 Participants53 Participants
Ethnicity (NIH/OMB)
Unknown or Not Reported
0 Participants0 Participants0 Participants0 Participants0 Participants0 Participants
Race (NIH/OMB)
American Indian or Alaska Native
0 Participants0 Participants0 Participants0 Participants0 Participants0 Participants
Race (NIH/OMB)
Asian
6 Participants0 Participants2 Participants0 Participants1 Participants9 Participants
Race (NIH/OMB)
Black or African American
0 Participants0 Participants1 Participants0 Participants1 Participants2 Participants
Race (NIH/OMB)
More than one race
0 Participants0 Participants0 Participants0 Participants0 Participants0 Participants
Race (NIH/OMB)
Native Hawaiian or Other Pacific Islander
0 Participants0 Participants0 Participants0 Participants0 Participants0 Participants
Race (NIH/OMB)
Unknown or Not Reported
0 Participants0 Participants0 Participants0 Participants0 Participants0 Participants
Race (NIH/OMB)
White
5 Participants12 Participants12 Participants10 Participants8 Participants47 Participants
Sex: Female, Male
Female
8 Participants7 Participants8 Participants3 Participants5 Participants31 Participants
Sex: Female, Male
Male
3 Participants5 Participants7 Participants7 Participants5 Participants27 Participants

Adverse events

Event typeEG000
affected / at risk
EG001
affected / at risk
EG002
affected / at risk
EG003
affected / at risk
EG004
affected / at risk
deaths
Total, all-cause mortality
0 / 110 / 120 / 150 / 100 / 10
other
Total, other adverse events
11 / 1111 / 1215 / 1510 / 109 / 10
serious
Total, serious adverse events
4 / 114 / 129 / 156 / 105 / 10

Outcome results

Primary

Cohort 1: Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Day 364 (Visit 15) [Month 12]

The Revised Hammersmith Scale (RHS) is a 36 item clinical assessment of physical abilities in patients with Type 2 SMA and ambulatory or nonambulatory patients with Type 3 SMA. For the ambulatory Type 3 patients 5-21 years of age in Cohort 1 (N=23), the primary endpoint was the change from baseline in RHS total score at month 12. The RHS has a minimum achievable score of 0 and a maximum achievable score of 69. The RHS includes 33 items that are graded on a scale of 0, 1, 2, where 0 denotes the lowest level and 2 denotes the highest level of ability/function. The remaining 3 items are scored 0 or 1, where 0 denotes an inability and 1 denotes an ability to achieve. Higher scores indicate increased motor function. A positive change from Baseline indicates improvement.

Time frame: Baseline up to 12 months

Population: The ITT Population: all enrolled/randomized patients who receive at least 1 dose of study drug. The ITT Population was the main population for analysis of efficacy endpoints; the analysis includes all assessments from all patients with the exception of assessments after missing 3 consecutive doses due to site access restrictions caused by COVID-19. The last observation carried forward (LOCF) method was used to impute the 12-month primary endpoint for data missing for other reasons.

ArmMeasureValue (MEAN)Dispersion
Cohort 1 - MonotherapyCohort 1: Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Day 364 (Visit 15) [Month 12]-0.1 score on a scaleStandard Deviation 5.01
Cohort 1 - Dual TherapyCohort 1: Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Day 364 (Visit 15) [Month 12]0.0 score on a scaleStandard Deviation 2.56
Primary

Cohort 2 and Cohort 3: Change From Baseline in Hammersmith Functional Motor Scale Expanded (HFMSE) Total Score at Day 364 (Visit 15) [Month 12]

Cohort 2: For the nonambulatory Type 2 and Type 3 patients 5-21 years of age in Cohort 2 (N=15), the primary efficacy endpoint was the change from baseline in HFMSE total score at month 12. Cohort 3: For the nonambulatory Type 2 patients ≥2 years of age in Cohort 3 (N=20), the primary efficacy endpoint was the change from baseline in HFMSE total score at month 12. The Hammersmith Functional Motor Scale Expanded (HFMSE) assesses the physical abilities of patients with Type 2 and Type 3 SMA comprises 33 items graded on a scale of 0, 1, or 2, where 0 denotes unable, 1 denotes performed with modification or adaptation, and 2 denotes performed without modification or adaptation.

Time frame: Baseline up to 12 months

Population: The ITT Population: all enrolled/randomized patients who receive at least one dose of study drug. The ITT Population was the main population for analysis of efficacy endpoints; the analysis included all assessments from all patients with the exception of assessments after missing 3 consecutive doses due to site access restrictions caused by COVID-19. The last observation carried forward (LOCF) method was used to impute the 12-month primary endpoint for data missing for other reasons.

ArmMeasureValue (MEAN)Dispersion
Cohort 1 - MonotherapyCohort 2 and Cohort 3: Change From Baseline in Hammersmith Functional Motor Scale Expanded (HFMSE) Total Score at Day 364 (Visit 15) [Month 12]0.6 score on a scaleStandard Deviation 3.5
Cohort 1 - Dual TherapyCohort 2 and Cohort 3: Change From Baseline in Hammersmith Functional Motor Scale Expanded (HFMSE) Total Score at Day 364 (Visit 15) [Month 12]5.3 score on a scaleStandard Deviation 8.93
Cohort 3 - High DoseCohort 2 and Cohort 3: Change From Baseline in Hammersmith Functional Motor Scale Expanded (HFMSE) Total Score at Day 364 (Visit 15) [Month 12]7.1 score on a scaleStandard Deviation 6.42
Secondary

Cohort 1: Change From Baseline in 10-Meter Walk/Run (From RHS)

The 10 Meter Walk/Run test is an enhanced function of the RHS used for ambulatory patients with Type 3 SMA. It is a measure of the time taken to walk/run 10 meters. The time to perform is summarized only for patients able to complete the RHS 10-meter walk/run item.

Time frame: Baseline to 12 months

ArmMeasureValue (MEAN)Dispersion
Cohort 1 - MonotherapyCohort 1: Change From Baseline in 10-Meter Walk/Run (From RHS)0.1 SecondsStandard Deviation 0.32
Cohort 1 - Dual TherapyCohort 1: Change From Baseline in 10-Meter Walk/Run (From RHS)0.9 SecondsStandard Deviation 3.32
Secondary

Cohort 1: Change From Baseline in 30-Second Sit-to-Stand

The 30-Second Sit-to-Stand Test is an assessment of functional lower-limb strength that measures the maximal number of times a patient can transition from sitting to standing in 30 seconds.

Time frame: Baseline to 12 months

ArmMeasureValue (MEAN)Dispersion
Cohort 1 - MonotherapyCohort 1: Change From Baseline in 30-Second Sit-to-Stand-0.6 StandsStandard Deviation 1.63
Cohort 1 - Dual TherapyCohort 1: Change From Baseline in 30-Second Sit-to-Stand-0.2 StandsStandard Deviation 1.95
Secondary

Cohort 1: Change From Baseline in 6-Minute Walk Test (6MWT)

6-Minute Walk Test The 6-Minute Walk Test (6MWT) is an assessment of exercise capacity and fatigue used for ambulatory patients with later-onset SMA who are directed to walk along a 25 meter course as fast as possible over 6 minutes.

Time frame: Baseline to 12 months

ArmMeasureValue (MEAN)Dispersion
Cohort 1 - MonotherapyCohort 1: Change From Baseline in 6-Minute Walk Test (6MWT)-20.6 MetersStandard Deviation 44.96
Cohort 1 - Dual TherapyCohort 1: Change From Baseline in 6-Minute Walk Test (6MWT)11.0 MetersStandard Deviation 33.67
Secondary

Cohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints

The Revised Hammersmith Scale (RHS) is a 36 item clinical assessment of physical abilities in patients with Type 2 SMA and ambulatory or nonambulatory patients with Type 3 SMA; it has a maximum achievable score of 69. The RHS includes 33 items that are graded on a scale of 0, 1, 2, where 0 denotes the lowest level and 2 denotes the highest level of ability/function. The remaining 3 items are scored 0 or 1, where 0 denotes an inability and 1 denotes an ability to achieve.

Time frame: Baseline to 12 months

Population: 1 patient in Cohort 1 Monotherapy did not complete Physical Therapy Assessments at V6 due to site imposed COVID-19 restrictions.~1 patient in Cohort 1 Dual Therapy withdrew consent following discontinuation of apitegromab after 3 months of treatment due to a nonserious TEAE of unresolved fatigue assessed as not related to apitegromab.

ArmMeasureGroupValue (COUNT_OF_PARTICIPANTS)
Cohort 1 - MonotherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥5pt at Day 56 (V4)1 Participants
Cohort 1 - MonotherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥5pt at Day 112 (V6)1 Participants
Cohort 1 - MonotherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥5pt at Day 168 (V8)2 Participants
Cohort 1 - MonotherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥5pt Month 12 Endpoint1 Participants
Cohort 1 - MonotherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥3pt at Day 56 (V4)3 Participants
Cohort 1 - MonotherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥3pt at Day 112 (V6)1 Participants
Cohort 1 - MonotherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥3pt at Day 168 (V8)4 Participants
Cohort 1 - MonotherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥3pt at Month 12 Endpoint3 Participants
Cohort 1 - MonotherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥1pt at Day 56 (V4)8 Participants
Cohort 1 - MonotherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥1pt at Day 112 (V6)3 Participants
Cohort 1 - MonotherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥1pt at Day 168 (V8)7 Participants
Cohort 1 - MonotherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥1pt at Month 12 Endpoint6 Participants
Cohort 1 - MonotherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified TimepointsNo Change at Day 56 (V4)1 Participants
Cohort 1 - MonotherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified TimepointsNo Change at Day 112 (V6)5 Participants
Cohort 1 - MonotherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified TimepointsNo Change at Day 168 (V8)1 Participants
Cohort 1 - MonotherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified TimepointsNo Change at Month 12 Endpoint0 Participants
Cohort 1 - MonotherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified TimepointsDecrease at Day 56 (V4)2 Participants
Cohort 1 - MonotherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified TimepointsDecrease at Day 112 (V6)2 Participants
Cohort 1 - MonotherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified TimepointsDecrease at Day 168 (V8)3 Participants
Cohort 1 - MonotherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified TimepointsDecrease at Month 12 Endpoint5 Participants
Cohort 1 - Dual TherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified TimepointsDecrease at Day 112 (V6)5 Participants
Cohort 1 - Dual TherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥5pt at Day 56 (V4)1 Participants
Cohort 1 - Dual TherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥1pt at Day 168 (V8)4 Participants
Cohort 1 - Dual TherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥5pt at Day 112 (V6)1 Participants
Cohort 1 - Dual TherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified TimepointsNo Change at Month 12 Endpoint2 Participants
Cohort 1 - Dual TherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥5pt at Day 168 (V8)1 Participants
Cohort 1 - Dual TherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥1pt at Month 12 Endpoint5 Participants
Cohort 1 - Dual TherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥5pt Month 12 Endpoint0 Participants
Cohort 1 - Dual TherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified TimepointsDecrease at Month 12 Endpoint5 Participants
Cohort 1 - Dual TherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥3pt at Day 56 (V4)3 Participants
Cohort 1 - Dual TherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified TimepointsNo Change at Day 56 (V4)1 Participants
Cohort 1 - Dual TherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥3pt at Day 112 (V6)2 Participants
Cohort 1 - Dual TherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified TimepointsDecrease at Day 56 (V4)3 Participants
Cohort 1 - Dual TherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥3pt at Day 168 (V8)1 Participants
Cohort 1 - Dual TherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified TimepointsNo Change at Day 112 (V6)1 Participants
Cohort 1 - Dual TherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥3pt at Month 12 Endpoint3 Participants
Cohort 1 - Dual TherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified TimepointsDecrease at Day 168 (V8)2 Participants
Cohort 1 - Dual TherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥1pt at Day 56 (V4)8 Participants
Cohort 1 - Dual TherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified TimepointsNo Change at Day 168 (V8)5 Participants
Cohort 1 - Dual TherapyCohort 1:Change From Baseline in the Revised Hammersmith Scale (RHS) Total Score at Other Prespecified Timepoints≥1pt at Day 112 (V6)5 Participants
Secondary

Cohort 1: Change From Baseline in Timed Rise From Floor (From RHS)

The timed rise from floor test is an enhanced function of the RHS used for ambulatory patients with Type 3 SMA. It is a measure of the time taken to rise to standing from the floor. The time to rise from floor is summarized only for patients able to complete the RHS rise from floor item.

Time frame: Baseline to 12 months

ArmMeasureValue (MEAN)Dispersion
Cohort 1 - MonotherapyCohort 1: Change From Baseline in Timed Rise From Floor (From RHS)0.6 SecondsStandard Deviation 1.75
Cohort 1 - Dual TherapyCohort 1: Change From Baseline in Timed Rise From Floor (From RHS)-0.6 SecondsStandard Deviation 1.43
Secondary

Cohort 1: Proportion of Patients Achieving Various Magnitudes of Change in RHS Score From Baseline

The Revised Hammersmith Scale (RHS) is a 36 item clinical assessment of physical abilities in patients with Type 2 SMA and ambulatory or nonambulatory patients with Type 3 SMA; it has a maximum achievable score of 69. The RHS includes 33 items that are graded on a scale of 0, 1, 2, where 0 denotes the lowest level and 2 denotes the highest level of ability/function. The remaining 3 items are scored 0 or 1, where 0 denotes an inability and 1 denotes an ability to achieve.

Time frame: Baseline to 12 months

ArmMeasureGroupValue (COUNT_OF_PARTICIPANTS)
Cohort 1 - MonotherapyCohort 1: Proportion of Patients Achieving Various Magnitudes of Change in RHS Score From Baseline≥3pt increase3 Participants
Cohort 1 - MonotherapyCohort 1: Proportion of Patients Achieving Various Magnitudes of Change in RHS Score From Baseline≥1pt increase6 Participants
Cohort 1 - MonotherapyCohort 1: Proportion of Patients Achieving Various Magnitudes of Change in RHS Score From BaselineNo Change0 Participants
Cohort 1 - MonotherapyCohort 1: Proportion of Patients Achieving Various Magnitudes of Change in RHS Score From BaselineDecrease5 Participants
Cohort 1 - Dual TherapyCohort 1: Proportion of Patients Achieving Various Magnitudes of Change in RHS Score From BaselineDecrease5 Participants
Cohort 1 - Dual TherapyCohort 1: Proportion of Patients Achieving Various Magnitudes of Change in RHS Score From Baseline≥3pt increase3 Participants
Cohort 1 - Dual TherapyCohort 1: Proportion of Patients Achieving Various Magnitudes of Change in RHS Score From BaselineNo Change2 Participants
Cohort 1 - Dual TherapyCohort 1: Proportion of Patients Achieving Various Magnitudes of Change in RHS Score From Baseline≥1pt increase5 Participants
Secondary

Cohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints

The Hammersmith Functional Motor Scale Expanded (HFMSE) assesses the physical abilities of patients with Type 2 and Type 3 SMA comprises 33 items graded on a scale of 0, 1, or 2, where 0 denotes unable, 1 denotes performed with modification or adaptation, and 2 denotes performed without modification or adaptation.

Time frame: Baseline to 12 months

Population: 1 patient in Cohort 2 and 3 patients in Cohort 3 (1 low dose and 2 high dose) missed 3 consecutive doses of apitegromab during the 12-month treatment period due to COVID-19-related site access restrictions and were not included in the primary analysis. In addition, 2 cohort 3 low dose patients skipped motor assessments at Day 168 (V8) and 1 cohort low dose patient at Day 365 (V15) due to COVID restrictions.

ArmMeasureGroupValue (COUNT_OF_PARTICIPANTS)
Cohort 1 - MonotherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsNo Change at Day 112 (V6)5 Participants
Cohort 1 - MonotherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥3pt at Month 12 Endpoint4 Participants
Cohort 1 - MonotherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥5pt at Day 56 (V4)1 Participants
Cohort 1 - MonotherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsNo Change at Day 56 (V4)4 Participants
Cohort 1 - MonotherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥1pt at Day 56 (V4)4 Participants
Cohort 1 - MonotherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsDecrease at Day 112 (V6)3 Participants
Cohort 1 - MonotherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥1pt at Month 12 Endpoint9 Participants
Cohort 1 - MonotherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥1pt at Day 112 (V6)6 Participants
Cohort 1 - MonotherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥5pt at Month 12 Endpoint2 Participants
Cohort 1 - MonotherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥1pt at Day 168 (V8)10 Participants
Cohort 1 - MonotherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥5pt at Day 112 (V6)1 Participants
Cohort 1 - MonotherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsDecrease at Day 56 (V4)7 Participants
Cohort 1 - MonotherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥3pt at Day 56 (V4)1 Participants
Cohort 1 - MonotherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsDecrease at Month 12 Endpoint4 Participants
Cohort 1 - MonotherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsNo Change at Month 12 Endpoint1 Participants
Cohort 1 - MonotherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥3pt at Day 112 (V6)2 Participants
Cohort 1 - MonotherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsDecrease at Day 168 (V8)3 Participants
Cohort 1 - MonotherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsNo Change at Day 168 (V8)1 Participants
Cohort 1 - MonotherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥3pt at Day 168 (V8)2 Participants
Cohort 1 - MonotherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥5pt at Day 168 (V8)1 Participants
Cohort 1 - Dual TherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥5pt at Day 168 (V8)3 Participants
Cohort 1 - Dual TherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥5pt at Day 56 (V4)0 Participants
Cohort 1 - Dual TherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥5pt at Day 112 (V6)2 Participants
Cohort 1 - Dual TherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥5pt at Month 12 Endpoint5 Participants
Cohort 1 - Dual TherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥3pt at Day 56 (V4)4 Participants
Cohort 1 - Dual TherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥3pt at Day 112 (V6)3 Participants
Cohort 1 - Dual TherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥3pt at Day 168 (V8)4 Participants
Cohort 1 - Dual TherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥3pt at Month 12 Endpoint5 Participants
Cohort 1 - Dual TherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥1pt at Day 56 (V4)6 Participants
Cohort 1 - Dual TherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥1pt at Day 112 (V6)5 Participants
Cohort 1 - Dual TherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥1pt at Day 168 (V8)5 Participants
Cohort 1 - Dual TherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsNo Change at Day 56 (V4)1 Participants
Cohort 1 - Dual TherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsNo Change at Day 112 (V6)2 Participants
Cohort 1 - Dual TherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsNo Change at Day 168 (V8)1 Participants
Cohort 1 - Dual TherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsNo Change at Month 12 Endpoint0 Participants
Cohort 1 - Dual TherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsDecrease at Day 56 (V4)3 Participants
Cohort 1 - Dual TherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsDecrease at Day 112 (V6)3 Participants
Cohort 1 - Dual TherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsDecrease at Day 168 (V8)1 Participants
Cohort 1 - Dual TherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsDecrease at Month 12 Endpoint2 Participants
Cohort 1 - Dual TherapyCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥1pt at Month 12 Endpoint7 Participants
Cohort 3 - High DoseCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥3pt at Day 112 (V6)5 Participants
Cohort 3 - High DoseCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsDecrease at Month 12 Endpoint1 Participants
Cohort 3 - High DoseCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsNo Change at Day 168 (V8)0 Participants
Cohort 3 - High DoseCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥3pt at Day 56 (V4)5 Participants
Cohort 3 - High DoseCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsDecrease at Day 168 (V8)0 Participants
Cohort 3 - High DoseCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsNo Change at Month 12 Endpoint0 Participants
Cohort 3 - High DoseCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥5pt at Month 12 Endpoint5 Participants
Cohort 3 - High DoseCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥5pt at Day 56 (V4)3 Participants
Cohort 3 - High DoseCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsDecrease at Day 56 (V4)1 Participants
Cohort 3 - High DoseCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥5pt at Day 168 (V8)4 Participants
Cohort 3 - High DoseCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥1pt at Day 112 (V6)9 Participants
Cohort 3 - High DoseCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥1pt at Month 12 Endpoint7 Participants
Cohort 3 - High DoseCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥1pt at Day 168 (V8)8 Participants
Cohort 3 - High DoseCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥1pt at Day 56 (V4)8 Participants
Cohort 3 - High DoseCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥3pt at Month 12 Endpoint5 Participants
Cohort 3 - High DoseCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsDecrease at Day 112 (V6)0 Participants
Cohort 3 - High DoseCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsNo Change at Day 56 (V4)1 Participants
Cohort 3 - High DoseCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥3pt at Day 168 (V8)5 Participants
Cohort 3 - High DoseCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified Timepoints≥5pt at Day 112 (V6)5 Participants
Cohort 3 - High DoseCohort 2 &3: Change From Baseline in HFMSE Total Score at Other Prespecified TimepointsNo Change at Day 112 (V6)1 Participants
Secondary

Cohort 2 & 3: Change in Baseline in Revised Upper Limb Module (RULM) Total Score

The RULM is a 20 item assessment of upper limb function in nonambulatory patients with SMA that was performed for patients who were 30 months of age or older at baseline. The 19 scored items assess functions that relate to everyday life, such as pressing a button and picking up a token; these items are scored 0, 1, or 2, where 0 denotes unable, 1 denotes able with modification, and 2 denotes able with no modification. The maximum score achievable is 37.

Time frame: Baseline to 12 months

Population: 1 patient in Cohort 2 and 3 patients in Cohort 3 missed 3 consecutive doses of apitegromab during the 12-month treatment period due to COVID-19-related site access restrictions and were not included in the primary analysis.

ArmMeasureValue (MEAN)Dispersion
Cohort 1 - MonotherapyCohort 2 & 3: Change in Baseline in Revised Upper Limb Module (RULM) Total Score1.2 Score on scaleStandard Deviation 2.99
Cohort 1 - Dual TherapyCohort 2 & 3: Change in Baseline in Revised Upper Limb Module (RULM) Total Score0.9 Score on scaleStandard Deviation 2.62
Cohort 3 - High DoseCohort 2 & 3: Change in Baseline in Revised Upper Limb Module (RULM) Total Score1 Score on scaleStandard Deviation 2.94
Secondary

Cohort 2 & 3: Proportion of Patients Achieving a New WHO Motor Development Milestones Relative to Baseline

The WHO Multicenter Growth Reference Study performance criteria is being utilized to assess the World Health Organization (WHO) motor development milestones of patients with Type 2 and nonambulatory Type 3 SMA enrolled in Cohort 2 and Cohort 3 relative to baseline. The WHO milestone assessment consists of six items which were selected because they have been considered to be universal, fundamental, and simple to test and evaluate, they include 1) sitting without support, 2) hands and knees crawling, 3) standing with assistance, 4) walking with assistance, 5) standing alone, and 6) walking without assistance. Each item is recorded as 1 (unable), 2 (refusal), 3 (Yes) or 9 (did not test). The number of 3s was counted as the final score. The minimum was 0, which means no motor milestones were achieved; the maximum was 6, which means all 6 milestones were achieved.

Time frame: Baseline to 12 months

Population: 1 patient in Cohort 2 and 3 patients in Cohort 3 missed 3 consecutive doses of apitegromab during the 12-month treatment period due to COVID-19-related site access restrictions and were not included in the primary analysis.

ArmMeasureGroupValue (COUNT_OF_PARTICIPANTS)
Cohort 1 - MonotherapyCohort 2 & 3: Proportion of Patients Achieving a New WHO Motor Development Milestones Relative to BaselineDecrease0 Participants
Cohort 1 - MonotherapyCohort 2 & 3: Proportion of Patients Achieving a New WHO Motor Development Milestones Relative to BaselineNo Change11 Participants
Cohort 1 - MonotherapyCohort 2 & 3: Proportion of Patients Achieving a New WHO Motor Development Milestones Relative to Baseline≥1pt increase3 Participants
Cohort 1 - MonotherapyCohort 2 & 3: Proportion of Patients Achieving a New WHO Motor Development Milestones Relative to Baseline≥2pt increase1 Participants
Cohort 1 - Dual TherapyCohort 2 & 3: Proportion of Patients Achieving a New WHO Motor Development Milestones Relative to Baseline≥2pt increase0 Participants
Cohort 1 - Dual TherapyCohort 2 & 3: Proportion of Patients Achieving a New WHO Motor Development Milestones Relative to Baseline≥1pt increase1 Participants
Cohort 1 - Dual TherapyCohort 2 & 3: Proportion of Patients Achieving a New WHO Motor Development Milestones Relative to BaselineNo Change7 Participants
Cohort 1 - Dual TherapyCohort 2 & 3: Proportion of Patients Achieving a New WHO Motor Development Milestones Relative to BaselineDecrease1 Participants
Cohort 3 - High DoseCohort 2 & 3: Proportion of Patients Achieving a New WHO Motor Development Milestones Relative to Baseline≥1pt increase1 Participants
Cohort 3 - High DoseCohort 2 & 3: Proportion of Patients Achieving a New WHO Motor Development Milestones Relative to BaselineDecrease1 Participants
Cohort 3 - High DoseCohort 2 & 3: Proportion of Patients Achieving a New WHO Motor Development Milestones Relative to Baseline≥2pt increase1 Participants
Cohort 3 - High DoseCohort 2 & 3: Proportion of Patients Achieving a New WHO Motor Development Milestones Relative to BaselineNo Change6 Participants
Secondary

Cohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in HFMSE Score From Baseline

The Hammersmith Functional Motor Scale Expanded (HFMSE) assesses the physical abilities of patients with Type 2 and Type 3 SMA comprises 33 items graded on a scale of 0, 1, or 2, where 0 denotes unable, 1 denotes performed with modification or adaptation, and 2 denotes performed without modification or adaptation.

Time frame: Baseline to 12 months

Population: 1 patient in Cohort 2 and 3 patients in Cohort 3 missed 3 consecutive doses of apitegromab during the 12-month treatment period due to COVID-19-related site access restrictions and were not included in the primary analysis.

ArmMeasureGroupValue (COUNT_OF_PARTICIPANTS)
Cohort 1 - MonotherapyCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in HFMSE Score From Baseline≥1pt increase9 Participants
Cohort 1 - MonotherapyCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in HFMSE Score From BaselineDecrease4 Participants
Cohort 1 - MonotherapyCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in HFMSE Score From Baseline≥3pt increase4 Participants
Cohort 1 - MonotherapyCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in HFMSE Score From BaselineNo Change1 Participants
Cohort 1 - Dual TherapyCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in HFMSE Score From BaselineNo Change0 Participants
Cohort 1 - Dual TherapyCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in HFMSE Score From Baseline≥3pt increase5 Participants
Cohort 1 - Dual TherapyCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in HFMSE Score From BaselineDecrease2 Participants
Cohort 1 - Dual TherapyCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in HFMSE Score From Baseline≥1pt increase7 Participants
Cohort 3 - High DoseCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in HFMSE Score From BaselineNo Change0 Participants
Cohort 3 - High DoseCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in HFMSE Score From Baseline≥3pt increase5 Participants
Cohort 3 - High DoseCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in HFMSE Score From Baseline≥1pt increase7 Participants
Cohort 3 - High DoseCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in HFMSE Score From BaselineDecrease1 Participants
Secondary

Cohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in RULM Score From Baseline

The RULM is a 20 item assessment of upper limb function in nonambulatory patients with SMA that was performed for patients who were 30 months of age or older at baseline. The 19 scored items assess functions that relate to everyday life, such as pressing a button and picking up a token; these items are scored 0, 1, or 2, where 0 denotes unable, 1 denotes able with modification, and 2 denotes able with no modification. The maximum score achievable is 37.

Time frame: Baseline to 12 months

Population: 1 patient in Cohort 2 and 3 patients in Cohort 3 missed 3 consecutive doses of apitegromab during the 12-month treatment period due to COVID-19-related site access restrictions and were not included in the primary analysis.

ArmMeasureGroupValue (COUNT_OF_PARTICIPANTS)
Cohort 1 - MonotherapyCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in RULM Score From Baseline≥2pt increase5 Participants
Cohort 1 - MonotherapyCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in RULM Score From Baseline≥1pt increase8 Participants
Cohort 1 - MonotherapyCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in RULM Score From BaselineNo change1 Participants
Cohort 1 - MonotherapyCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in RULM Score From BaselineDecrease5 Participants
Cohort 1 - Dual TherapyCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in RULM Score From BaselineDecrease3 Participants
Cohort 1 - Dual TherapyCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in RULM Score From Baseline≥2pt increase3 Participants
Cohort 1 - Dual TherapyCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in RULM Score From BaselineNo change3 Participants
Cohort 1 - Dual TherapyCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in RULM Score From Baseline≥1pt increase3 Participants
Cohort 3 - High DoseCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in RULM Score From BaselineDecrease2 Participants
Cohort 3 - High DoseCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in RULM Score From Baseline≥1pt increase3 Participants
Cohort 3 - High DoseCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in RULM Score From BaselineNo change2 Participants
Cohort 3 - High DoseCohort 2 & 3: Proportion of Patients Achieving Various Magnitudes of Change in RULM Score From Baseline≥2pt increase2 Participants

Source: ClinicalTrials.gov · Data processed: Feb 9, 2026