Nusinersen has demonstrated a favorable benefit:risk profile and shown significant and clinically meaningful efficacy on motor function across a broad spectrum of SMA populations, and event-free survival (EFS; time to death or permanent ventilation) in infantile-onset SMA. The current analyses report interim results from the SHINE study (NCT02594124) for individuals with infantile-onset SMA who transitioned from ENDEAR. SHINE is an open-label extension study for infants/children who participated in the nusinersen clinical trial program. Nusinersen doses were administered according to participant's previous trial cohort/regimen. The primary endpoint is safety/tolerability; secondary endpoints include achievement of HINE-2 motor milestones and EFS. The cutoff date was June 30, 2017; 89 infants transitioned from ENDEAR, 65/81 were previously randomized to nusinersen and 24/41 to sham-control. Within SHINE only, 83 infants had an adverse event (AE); most frequent AEs were pyrexia and upper respiratory tract infection; no treatment-related serious AEs. Mean (95%CI) change in HINE-2 total score from nusinersen initiation to last observed visit was 1.1 (0.20-1.90) for infants who received sham-control in ENDEAR and nusinersen in SHINE (n=20/24) and 5.8 (4.58-7.04) for those who received nusinersen in ENDEAR and SHINE (n=74/81; pooled ENDEAR/SHINE data). Median (95%CI) EFS time among sham-control infants in ENDEAR was 22.6 (13.6-31.3) weeks vs 73.0 (36.3-NA) weeks for those who received nusinersen in ENDEAR and SHINE. For infants who received nusinersen in ENDEAR and SHINE, 23/81 (28%) achieved full head control and 12/81 (15%) independent sitting as their highest motor milestone; no infants had yet achieved standing unaided/walking independently, although some made gains in precursors to both. Motor function and EFS improved in infants who initiated nusinersen in ENDEAR and motor function stabilized or started to show improvement in those who initiated nusinersen in SHINE.