A Phase 1/2 interventional study of GB221 in Spinal Muscular Atrophy Type I, sponsored by Gemma Biotherapeutics. Recruiting at 1 site in Brazil. Open to participants aged 2 Weeks to 12 Months. Per ClinicalTrials.gov, last updated 2026-06-29.
Sponsored by Gemma Biotherapeutics · Phase 1/2, Interventional, and Treatment
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:
61 studies on the registry are indexed under Spinal Muscular Atrophies of Childhood; 18 are open to participants now.
This study's planned enrollment of 22 is above the median of 15 across 41 interventional studies indexed under Spinal Muscular Atrophies of Childhood.
Browse Spinal Muscular Atrophies of Childhood studies →Gemma Biotherapeutics is the lead sponsor of 3 studies on the registry; 1 is open to participants now.
Counted across the registry records on this site, refreshed daily.
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.
Symptomatic Participants
Presymptomatic Participants
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 human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
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.
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
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.
Excipients
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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.
Biological: GB221
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.
Biological: GB221
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.
Biological: GB221
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.
Biological: GB221
GB221
Number of participants with treatment-related adverse events (AEs) and serious adverse events (SAEs) at Grade 3 or higher as characterized by CTCAEv5.0
Assess the number of treatment-related AEs and SAEs as characterized by CTCAEv5.0
Time frame: Up to 18 months across multiple visits
Number of Participants with Clinically Significant Changes in Physical Functions
Assess the number of participants with clinically significant changes in physical functions.
Time frame: Up to 18 months across multiple visits
Number of Participants with Clinically Significant Changes in Neurological Functions
Assess the number of participants with clinically significant changes in neurological functions.
Time frame: Up to 18 months across multiple visits
Number of Participants with Clinically Significant Changes in Vital signs
Assess the number of participants with clinically significant changes in vital signs.
Time frame: Up to 18 months across multiple visits
Change in electrocardiogram results
ECG will measure RR interval, P Wave, PR interval, PR segment, QRS Complex, ST segment, T wave and QT Interval.
Time frame: Up to 18 months across multiple visits
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
Assess the number of participants with clinically significant laboratory changes including hematology, serum chemistry, and coagulation tests.
Time frame: Up to 18 months across multiple visits
Number of Participants with Clinically Significant Laboratory Abnormalities as Measured Using Urine and CSF Tests
Assess the number of participants with clinically significant laboratory changes including urine and CSF tests.
Time frame: Up to 18 months across multiple visits
Change in markers of immunogenicity
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.
Time frame: Up to 18 months across multiple visits
Assess the number of participants who experience permanent ventilation or death
Time frame: 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.
* improvement in at least one category, i.e., an increase in the score for head control, rolling, sitting, crawling, standing, or walking of ≥1 point, * an increase in the score for kicking of ≥2 points, or achievement of the maximal score for kicking.
Time frame: 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.
Assess 16 types of muscle movements, each given a score from zero (the person can't complete the movement) to 4 (the person can complete the movement on their own, without assistance) to produce a score of 0 to 64.
Time frame: Baseline, 6 months and 18 months post dose.
Plan to share: No
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Studies of the drug tested here: GB221
Spinal Muscular Atrophies of Childhood →
Gemma Biotherapeutics