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Clinical Trials/NCT07070999
NCT07070999RecruitingPhase 1

A Phase 1-2, Open-Label, Multicenter Study to Assess the Safety, Tolerability and Efficacy of a Single Dose of GB221 Delivered Into the Cisterna Magna of Pediatric Participants From 2 Weeks to Younger Than 12 Months of Age With Spinal Muscular Atrophy Type 1

Gemma Biotherapeutics1 site in 1 country22 target enrollmentStarted: January 6, 2026Last updated:
Interventions
Drugs

Trial Snapshot

Phase
Phase 1
Status
Recruiting
Sponsor
Enrollment
22
Locations
1
Primary Endpoint
Number of participants with treatment-related adverse events (AEs) and serious adverse events (SAEs) at Grade 3 or higher as characterized by CTCAEv5.0

Study Overview

Brief Summary

GB221 is a gene therapy that delivers a working SMN1 gene to the motor neurons of people with spinal muscular atrophy (SMA) Type 1. This study will evaluate the safety, tolerability and efficacy of GB221 in two groups:

  1. participants aged from 2 weeks to younger than 12 months presenting with symptoms of SMA Type 1 who have never received a treatment OR are receiving the drug risdiplam
  2. participants aged from 2 weeks to younger than 5 months who are at risk of developing SMA Type 1 (presymptomatic) and have never received treatment OR are receiving the drug risdiplam.

Study Design

Study Type
Interventional
Allocation
Non Randomized
Intervention Model
Sequential
Primary Purpose
Treatment
Masking
None

Eligibility Criteria

Ages
2 Weeks to 12 Months (Child)
Sex
All
Accepts Healthy Volunteers
No

Inclusion Criteria

  • Symptomatic Participants
  • Diagnosis of SMA Type 1 based on gene mutation analysis with bi-allelic SMN1 mutations (deletion or point mutations) and up to 3 copies of SMN2
  • Participants must be 2 weeks to < 12 months of age at the time of dosing with disease onset of during the first 6 months of life.
  • Presymptomatic Participants
  • At risk of SMA Type 1 based on gene mutation analysis with bi-allelic SMN1 mutations (deletion or point mutations) and up to 2 copies of SMN2
  • Participants must be 2 weeks to < 5 months (< 150 days) of age at the time of dosing.

Exclusion Criteria

  • Any suspected or confirmed active viral infection at screening baseline (including HIV, Hepatitis B or C, or human T Cell lymphotropic viruses [HTLV])
  • History of invasive ventilatory support (tracheotomy with positive pressure) or pulse oximetry <95% saturation.
  • Ongoing immunosuppressive therapy or immunosuppressive therapy within 3 months of starting the trial (e.g. corticosteroids, cyclosporine, tacrolimus, methotrexate, cyclophosphamide, intravenous immunoglobulin, rituximab)
  • Participation in a recent SMA treatment clinical trial that, in the opinion of the Investigator, creates unnecessary risks for gene transfer.
  • Prior history of gene therapy for any indication, hematopoietic transplant or solid organ transplant
  • Subjects with severe scoliosis
  • Known allergy or hypersensitivity to prednisolone or other glucocorticosteroids or their excipients.

Arms & Interventions

Cohort 1A, safety and exploratory efficacy of a single dose in symptomatic participants

Experimental

Symptomatic participants with SMA Type 1 (up to 3 copies of SMN2), who are either treatment naïve or receiving risdiplam, with onset of disease during the first 6 months of life, aged from 2 weeks to younger than 12 months at the time of dosing.

Intervention: GB221 (Biological)

Cohort 1B, expansion phase for confirmatory testing in symptomatic participants

Experimental

Symptomatic participants with SMA Type 1 (up to 3 copies of SMN2), who are either treatment naïve or receiving risdiplam, with onset of disease during the first 6 months of life, aged from 2 weeks to younger than 12 months at the time of dosing.

Intervention: GB221 (Biological)

Cohort 2A, safety and exploratory efficacy of a single dose in presymptomatic participants

Experimental

Presymptomatic participants (treatment naïve or receiving risdiplam) at risk of developing SMA Type 1 (up to 2 copies of SMN2), aged from 2 weeks to younger than 5 months (< 150 days) at the time of dosing.

Intervention: GB221 (Biological)

Cohort 2B, expansion phase for confirmatory testing in presymptomatic participants

Experimental

Presymptomatic participants (treatment naïve or receiving risdiplam) at risk of developing SMA Type 1 (up to 2 copies of SMN2), aged from 2 weeks to younger than 5 months (< 150 days) at the time of dosing.

Intervention: GB221 (Biological)

Outcomes

Primary Outcomes

Number of participants with treatment-related adverse events (AEs) and serious adverse events (SAEs) at Grade 3 or higher as characterized by CTCAEv5.0

Time Frame: Up to 18 months across multiple visits

Assess the number of treatment-related AEs and SAEs as characterized by CTCAEv5.0

Number of Participants with Clinically Significant Changes in Physical Functions

Time Frame: Up to 18 months across multiple visits

Assess the number of participants with clinically significant changes in physical functions.

Number of Participants with Clinically Significant Changes in Neurological Functions

Time Frame: Up to 18 months across multiple visits

Assess the number of participants with clinically significant changes in neurological functions.

Change in electrocardiogram results

Time Frame: Up to 18 months across multiple visits

ECG will measure RR interval, P Wave, PR interval, PR segment, QRS Complex, ST segment, T wave and QT Interval.

Change in serum cardiac troponin I levels

Time Frame: Up to 18 months across multiple visits

Number of Participants with Clinically Significant Laboratory Abnormalities as Measured Using Hematology, Chemistry and Coagulation Tests

Time Frame: Up to 18 months across multiple visits

Assess the number of participants with clinically significant laboratory changes including hematology, serum chemistry, and coagulation tests.

Number of participants with treatment-related adverse events (AEs) and serious adverse events (SAEs) at Grade 3 or higher as characterized by CTCAEv5.0

Time Frame: Up to 18 months across multiple visits

Assess the number of treatment-related AEs and SAEs as characterized by CTCAEv5.0

Number of Participants with Clinically Significant Changes in Physical Functions

Time Frame: Up to 18 months across multiple visits

Assess the number of participants with clinically significant changes in physical functions.

Number of Participants with Clinically Significant Changes in Neurological Functions

Time Frame: Up to 18 months across multiple visits

Assess the number of participants with clinically significant changes in neurological functions.

Number of Participants with Clinically Significant Changes in Vital signs

Time Frame: Up to 18 months across multiple visits

Assess the number of participants with clinically significant changes in vital signs.

Change in electrocardiogram results

Time Frame: Up to 18 months across multiple visits

ECG will measure RR interval, P Wave, PR interval, PR segment, QRS Complex, ST segment, T wave and QT Interval.

Change in serum cardiac troponin I levels

Time Frame: Up to 18 months across multiple visits

Number of Participants with Clinically Significant Laboratory Abnormalities as Measured Using Hematology, Chemistry and Coagulation Tests

Time Frame: Up to 18 months across multiple visits

Assess the number of participants with clinically significant laboratory changes including hematology, serum chemistry, and coagulation tests.

Number of Participants with Clinically Significant Laboratory Abnormalities as Measured Using Urine and CSF Tests

Time Frame: Up to 18 months across multiple visits

Assess the number of participants with clinically significant laboratory changes including urine and CSF tests.

Change in markers of immunogenicity

Time Frame: Up to 18 months across multiple visits

Assessment of humoral (NAb and TAb titers) and T-cell (IFNγ ELISpot) immune responses to the AAVhu68 capsid and SMN transgene product in serum and CSF.

Secondary Outcomes

  • Assess the number of participants who experience permanent ventilation or death(Up to 18 months across multiple visits)
  • Percentage of infants with improvement in the motor milestones categories in Section 2 of the Hammersmith Infant Neurological Examination (HINE), with the exclusion of voluntary grasp.(Baseline, 6 months and 18 months post dose.)
  • Change from baseline in mean Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) Score.(Baseline, 6 months and 18 months post dose.)

Investigators

Sponsor
Gemma Biotherapeutics
Sponsor Class
Industry
Responsible Party
Sponsor

Study Sites (1)

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