Evaluation of Safety and Efficacy of Gene Therapy Drug in the Treatment of Spinal Muscular Atrophy (SMA) Type 2 Patients

Study Overview
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Brief Summary
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The study will evaluate safety and efficacy of intrathecal delivery of GC101 gene therapy drug as a treatment of spinal muscular atrophy Type 2 (SMA 2) patients.

Detailed Description
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The purpose of this trial is to evaluate safety and efficacy of gene therapy drug GC101 in SMA 2 patients. Open-label, dose-escalation clinical trial of GC101 will be conducted in multiple centers in China. GC101 will be administrated intrathecally. Short-term safety will be evaluated in 52 weeks and enter long-term follow-up study of 5 years at will. Patients will be tested at baseline and followed up on various time points. The primary analysis for efficacy will be assessed at 12 months after treatment with GC101 on the motor milestone of stand unassisted for at least 3 seconds for patients of age between 6 and 24 months, or changes from baseline HFMSE scores for patients of age between 24 and 60 months.

Official Title
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A Multi-center, Open Label, Single-arm, Dose Ascending Clinical Trial for Evaluation of Safety and Efficacy of Gene Therapy Drug GC101 in the Treatment of Spinal Muscular Atrophy (SMA) Type 2 Patients

Conditions
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SMA II

Intervention / Treatment
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* Genetic: GC101


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Between 6 months and 60 months of age on day of signing informed consent form; Patient with SMA Type 2 as defined by the following features: Diagnosis of SMA based on gene mutation analysis with bi-allelic SMN1 mutations (deletion or point mutations) and 2 copies of SMN Onset of disease between 6 and 18 months of age Patient who can sit alone but never be able to stand or walk alone ; The patient's legal guardian(s) must be able to understand the purpose and risks of the study and voluntarily provide signed and dated informed consent prior to any study-related procedures being performed. Exclusion Criteria: Patient who has participated in a previous gene therapy research trials; Patient who has received Nusinersen and Risdiplam treatment; Patient who has AAV9 neutralizing antibody titer ≥1:200; Patient with a point mutation in SMN2 (c.859G>C); Patient who requires non-invasive ventilatory support averaging≥12 hours/day at screening, or use invasive ventilatory support or pulse oximetry < 95% saturation while awake and calm at screening; Patient who is positive for human immunodeficiency virus (HIV) antibody, hepatitis B surface antigen, hepatitis C antibody, or treponema pallidum antibody; Abnormal laboratory values considered clinically significant, including gamma-glutamyl transferase(GGT), Aspartate aminotransferase (AST), alanine aminotransferase (ALT), bilirubin > 3x upper limit of normal (ULN), Hemoglobin (Hgb)< 110 or >150 g/L, platelet <lower limit of normal (LLN);Class IV patient based on Modified Ross Heart Failure Classification for Children; Patient with a history of glucocorticoid allergy; Contraindication that would interfere with the lumbar puncture procedures; Presence of an untreated active infection requiring systemic antiviral therapy at any time during the screening period; Vaccination less than 2 weeks before infusion of vector; Patient who has any concurrent clinically significant major disease or any other condition that, in the opinion of the Investigator, makes the subject unsuitable for participation in the study. Note: Other protocol defined inclusion/exclusion criteria may apply.

Ages Eligible for Study
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Minimum Age: 6 Months
Maximum Age: 60 Months

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Non-Randomized
Intervention Model: Sequential Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Low dosing group<br>1.2x10^14 vg/person of GC101 delivered one-time intrathecally (n=3) | Genetic: GC101<br>* Self-complementary AAV9 carrying a codon-optimized SMN coding sequence(coSMN1) driven by CMV enhancer and chicken β-actin promoter<br>|
| Experimental: Medium dosing group<br>2.4x10^14 vg/person of GC101 delivered one-time intrathecally (n=3) | Genetic: GC101<br>* Self-complementary AAV9 carrying a codon-optimized SMN coding sequence(coSMN1) driven by CMV enhancer and chicken β-actin promoter<br>|
| Experimental: High dosing group<br>4.8x10^14 vg/person of GC101 delivered one-time intrathecally (n=3) | Genetic: GC101<br>* Self-complementary AAV9 carrying a codon-optimized SMN coding sequence(coSMN1) driven by CMV enhancer and chicken β-actin promoter<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of Treatment-Emergent Adverse Events | Frequency of treatment-related adverse events (AEs), serious adverse events (SAEs), and changes from baseline in relevant clinical laboratory tests | 52 weeks | 
| Proportion of patients who can stand unassisted for at least 3 seconds at Month 12 |  | 52 weeks | 
| Change from baseline on Hammersmith Functional Motor Scale - Expanded (HFMSE) scores at Month 12 | HFMSE consists of 33 activities that can be scored one of three ways: 0 for unable to perform, 1 for performs with modification/adaptation, and 2 for performs without modification. | 52 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Proportion of patients treated with GC101 who achieve motor milestone of walk alone for 5 steps at Month 12 |  | 52 weeks |