Abstract
This Phase 3 trial (Study SRK-015-003) is being conducted in patients ≥2 years old at
Screening, who were previously diagnosed with later-onset spinal muscular atrophy (SMA)
(i.e., Type 2 and Type 3 SMA) and are receiving an approved survival motor neuron (SMN)
upregulator therapy (i.e., either nusinersen or risdiplam), to confirm the efficacy and
safety of apitegromab as an adjunctive therapy to nusinersen and evaluate the efficacy and
safety of apitegromab as an adjunctive therapy to risdiplam.

