Dataset from A Phase 2, Randomized, Double-blind, Sham-procedure Controlled Study to Assess the Safety and Tolerability and Explore the Efficacy of ISIS 396443 (BIIB058) Administered Intrathecally in Subjects With Spinal Muscular Atrophy Who Are Not Eligible to Participate in the Clinical Studies ISIS 396443-CS3B or ISIS 396443-CS4

The primary objective of Part 1 of this study is to assess the safety and tolerability of
Nusinersen in participants with SMA who are not eligible to participate in the clinical
studies ISIS 396443-CS3B (NCT02193074) or ISIS 396443-CS4 (NCT02292537). The secondary
objective of Part 1 of this study is to examine the pharmacokinetics (PK) of Nusinersen in
participants with SMA. The primary objective of Part 2 of this study is to assess the
long-term safety and tolerability of Nusinersen in participants with SMA who participated in
Part 1 and completed their End of Part 1 Evaluation assessments. The secondary objective of
Part 2 of this study is to examine the PK of Nusinersen in participants with SMA who
participated in Part 1 and completed their End of Part 1 Evaluation assessments.