Phase IIIb, Open-label, Multi-center Study to Evaluate Safety, Tolerability and Efficacy of OAV101 Administered Intrathecally to Participants With SMA Who Discontinued Treatment With Nusinersen or Risdiplam

Inclusion Criteria

• SMA diagnosis

• Aged 2 to < 18 years

• Have had at least four loading doses of nusinersen (Spinraza®) or at least 3 monthsof treatment with risdiplam (Evrysdi®) at Screening

• Must have symptoms of SMA as defined in the protocol

Exclusion Criteria:

• Anti Adeno Associated Virus Serotype 9 (AAV9) antibody titer using an immunoassay isreported as elevated

• Clinically significant abnormalities in test results during screening

• Contraindications for lumbar puncture procedure

• At Baseline, participants are excluded if they received:

• nusinersen (Spinraza®) or

• risdiplam (Evrysdi®) within a defined timeframe

• Vaccinations 2 weeks prior to administration of OAV101

• Hospitalization for a pulmonary event, or for nutritional support within 2 monthsprior to Screening or inpatient major surgery planned.

• Presence of an infection or febrile illness up to 30 days prior to administration ofOAV101

• Requiring invasive ventilation