Safety and Efficacy of Intravenous OAV101 (AVXS-101) in Pediatric Patients With Spinal Muscular Atrophy (SMA) (OFELIA)

Inclusion Criteria:

1. Written informed consent/assent obtained prior to any assessment performed

2. Symptomatic SMA diagnosis based on gene mutation analysis with bi-allelic SMN1mutations (deletion or point mutations) and any copy of SMN2 gene.

3. Age ≤ 24 months of age at time of treatment

4. Weight ≤17 kg at the time of Screening Period 4. Naïve to treatment or havediscontinued an approved drug/therapy 5. Up-to date on recommended childhoodvaccinations and RSV prophylaxis with palivizumab (also known as Synagis), per localstandard of care

Key Exclusion Criteria:

1. Previous use of OAV101 or any AAV9 gene therapy

2. Participant with history of aspiration pneumonia or signs of aspiration (eg,coughing or sputtering of food) within 4 weeks prior to Screening

3. Participant dependent on gastrostomy feeding tube for 100% of nutritional intake.

4. Anti-AAV9 antibody titer > 1:50 as determined by ligand binding immunoassay at thetime of screening

5. Inability to take corticosteroids

6. Concomitant use of immunosuppressive therapy, plasmapheresis, immunomodulators suchas adalimumab, or immunosuppressive therapy within 3 months prior to genereplacement therapy (eg, cyclosporine, tacrolimus, methotrexate, rituximabcyclophosphamide, IV immunoglobulin)

7. Hepatic dysfunction (i.e. AST, ALT, bilirubin, GGT or GLDH, ≥ ULN; CTCAE ≥ 1) atScreening (with the exception of isolated AST elevation: in the absence of otherliver laboratory abnormalities, isolated AST elevation is not consideredexclusionary)

8. Previously treated with nusinersen (Spinraza®) within 4 months prior to Screening

9. Previously treated with risdiplam (EvrysdiTM) within 15 days prior to Screening (washout period of at least 5 half-lives before Screening)