A Study to Assess the Efficacy and Safety of Nusinersen (ISIS 396443) in Participants With Later-onset Spinal Muscular Atrophy (SMA)

The HFMSE consists of 33 scored activities used to assess motor function in children with SMA. The scale was originally developed with 20 scored activities and was devised for use in children with SMA Type 2 and Type 3 with limited ambulation to give objective information on motor ability and clinical progression. The expanded scale includes an additional module of 13 items developed to allow for evaluation of ambulatory SMA patients. Participants were asked to do a specific activity (such as rolling) and they were then graded on the quality and execution of that movement on a scale of 0=being unable, 1=performed with some compensation, and 2=unaided. The overall score is the sum of the scores for all activities with a maximum achievable score of 66. Higher scores indicate increased motor function. A positive change from Baseline indicates improvement.

The HFMSE consists of 33 scored activities used to assess motor function in children with SMA. The scale was originally developed with 20 scored activities and was devised for use in children with SMA Type 2 and Type 3 with limited ambulation to give objective information on motor ability and clinical progression. The expanded scale includes an additional module of 13 items developed to allow for evaluation of ambulatory SMA patients. Participants were asked to do a specific activity (such as rolling) and they were then graded on the quality and execution of that movement on a scale of 0=being unable, 1=performed with some compensation, and 2=unaided. The overall score is the sum of the scores for all activities with a maximum achievable score of 66. Higher scores indicate increased motor function. A positive change from Baseline indicates improvement.

New motor milestones are defined as sitting without support, hands-and-knees crawling, standing with assistance, walking with assistance, standing alone and walking alone.

New motor milestones are defined as sitting without support, hands-and-knees crawling, standing with assistance, walking with assistance, standing alone and walking alone.

The RULM Test is used in patients with SMA to assess upper limb functional ability items that are reflective of activities of daily living (i.e., raise a can to mouth as if drinking, take a coin and place it in a box, remove the lid of a container). The RULM test has a total of 20 items with an entry item that serves as functional class identification and does not contribute to the total score. The remaining 19 scorable items reflect different functional domains and are graded on a 3-point system with a score of 0 (unable), 1 (able, with modification), and a maximum of 2 (able, no difficulty). There is only 1 item (item I) that is scored as a can/cannot score, with 1 as the highest score. Scorable items are summed for a total score range of 0-37, with higher scores increased great upper limb function. A positive change from Baseline indicates improvement.

If the participant was unable to achieve standing alone at Baseline but could achieve this at Month 15 then they were considered a responder. If they could not achieve this or if a participant terminated the study prior to the 15-month assessment due to treatment failure or death, then any imputed value was ignored and the participant was considered as a non-responder.

If the participant was unable to achieve walking with assistance at baseline but could achieve this at Month 15 then they were considered a responder. If they could not achieve this or if a participant terminated the study prior to the 15-month assessment due to treatment failure or death, then any imputed value was ignored and the participant was considered as a non-responder.

AEs: any sign, symptom, or diagnosis/disease that is unfavorable or unintended, that is new, or if pre-existing, worsens in participants administered a pharmaceutical product and that does not necessarily have a causal relationship with this treatment. SAEs: an event that results in death; an event that, in the view of the investigator, places the participant at immediate risk of death; an outcome that results in a congenital anomaly/birth defect diagnosed in a child of a participant; an event that requires or prolongs inpatient hospitalization; an event that results in persistent or significant disability/incapacity. Any other medically important event that, in the opinion of the investigator, may jeopardize the participant or may require intervention to prevent one of the other outcomes listed in the definition above.

Vital signs assessed for clinical significance include resting blood pressure, pulse, respiratory rate, and temperature.

Weight changes assessed from Baseline to Month 15.

Neurological changes assessed for clinical significance include assessment of mental status, level of consciousness, sensory function, motor function, cranial nerve function, and reflexes.

Physical examination changes were assessed for clinical significance.

Laboratory parameter changes assessed for clinical significance include serum chemistry, hematology, coagulation and urinalysis.

The number of participants with abnormal, clinically relevant worsening, defined as participants with an ECG interpreted as abnormal and clinically relevant, with a comparison with Baseline value is reported.

Concomitant medications include prescription and over-the-counter medications administered to participants on or after the first day of study treatment.