BACKGROUNDSpinal muscular atrophy is an autosomal recessive neuromuscular disorder that is caused by an insufficient level of survival motor neuron (SMN) protein. Nusinersen is an antisense oligonucleotide drug that modifies pre-messenger RNA splicing of the SMN2 gene and thus promotes increased production of full-length SMN protein. METHODSWe conducted a randomized, double-blind, sham-controlled, phase 3 efficacy and safety trial of nusinersen in infants with spinal muscular atrophy. The primary end points were a motor-milestone response (defined according to results on the Hammersmith Infant Neurological Examination) and event-free survival (time to death or the use of permanent assisted ventilation). Secondary end points included overall survival and subgroup analyses of event-free survival according to disease duration at screening. Only the first primary end point was tested in a prespecified interim analysis. To control the overall type I error rate at 0.05, a hierarchical testing strategy was used for the second primary end point and the secondary end points in the final analysis. RESULTSIn the interim analysis, a significantly higher percentage of infants in the nusinersen group than in the control group had a motor-milestone response (21 of 51 infants [41%] vs. 0 of 27 [0%], P<0.001), and this result prompted early termination of the trial. In the final analysis, a significantly higher percentage of infants in the nusinersen group than in the control group had a motor-milestone response (37 of 73 infants [51%] vs. 0 of 37 [0%]), and the likelihood of event-free survival was higher in the nusinersen group than in the control group (hazard ratio for death or the use of permanent assisted ventilation, 0.53; P = 0.005). The likelihood of overall survival was higher in the nusinersen group than in the control group (hazard ratio for death, 0.37; P = 0.004), and infants with a shorter disease duration at screening were more likely than those with a longer disease duration to benefit from nusinersen. The incidence and severity of adverse events were similar in the two groups. CONCLUSIONSAmong infants with spinal muscular atrophy, those who received nusinersen were more likely to be alive and have improvements in motor function than those in the control group. Early treatment may be necessary to maximize the benefit of the drug. (Funded by Biogen and Ionis Pharmaceuticals; ENDEAR ClinicalTrials.gov number, NCT02193074.)

This study documents measurement properties of reproducibility, positive criterion validity, and convergent validity with established clinical assessments and reaffirms the value of the 6MWT as a pivotal outcome measure in SMA clinical trials. Muscle Nerve 54: 836-842, 2016.

Background: Individuals and/or caregivers of individuals affected by spinal muscular atrophy (SMA) completed the 2019 Cure SMA Community Update Survey, online, assessing health-related quality of life (HRQoL), loss of work productivity, and fatigue using the Health Utilities Index Questionnaire (HUI), the Work Productivity and Activity Impairment Questionnaire (WPAI), and the Patient Reported Outcomes Measurement Information System Fatigue Short Form (PROMIS Fatigue SF), respectively. The purpose was to collect baseline quality of life results among individuals affected by SMA using the above Patient Reported Outcome Measures (PROMs). Results: Of 666 surveys completed between March and May 2019, 478 were included in this analysis, accounting for duplicates, missing data, or deaths. The breakdown across SMA type I, II and III was 25, 47 and 28%, respectively. Responses were characterized by current functional status/milestone, with subsets for "permanent ventilation," "non-sitters," "sitters," "walk with support," and "walk alone." WPAI and HUI respondents included affected adults and caregivers. The PROMIS Fatigue SF was completed by the primary caregiver of affected children. Overall, those affected by a less severe form of SMA and with a higher functional status reported higher HRQoL and lower work productivity and activity impairment. All affected individuals reported higher fatigue levels than the general population. Conclusions: This study offers useful insights into the burden of SMA among affected individuals and their caregivers. The results provide a baseline picture of the patient and caregiver experience with SMA in a posttreatment era from which to measure year-over-year changes in quality of life scores from new therapies and improved care. The WPAI demonstrates the significant impact of work productivity among SMA populations. Aspects of the HUI seem more appropriate to certain SMA sub-populations than others. Measures from the PROMIS Fatigue SF appear to under-represent the burden of fatigue often reported by SMA individuals and caregivers; this may, perhaps be due to a lack of sensitivity in the questions associated with fatigue in the SMA affected population, when compared with other studies on this topic. Overall, these results suggest the need for SMAspecific quality of life outcome measures to fully capture clinically meaningful change in the SMA population.

Background:The benefits of exercise on long-term health and well-being are well established. The possible benefits of exercise in Spinal Muscular Atrophy (SMA) have not been explored in a controlled clinical trial format.Objective:To assess the effects of exercise on measures of function, strength, and exercise capacity in ambulatory SMA patients.Methods:Fourteen participants, ages 10–48 years, were randomized to control and exercise cohorts after a 1 month lead-in period. The exercise group received 6 months of intervention. Thereafter, both groups received the intervention for the remaining 12 months. Participants were monitored for a total of 19 months. Exercise included individualized home-based cycling and strengthening. The primary outcome measure was distance walked during the six-minute walk test (6MWT). Secondary outcomes included strength, function, exercise capacity, quality of life and fatigue.Results:Twelve participants completed the first 7 months of the study, and 9 completed all 19 months. At baseline, the groups were similar on all clinical variables. There were no group changes at any time point in the 6MWT, fatigue, or function. Percent-predicted VO2 max improved 4.9% in all participants in 6 months (p = 0.036) (n = 10).Conclusion:Daily exercise is safe in ambulatory SMA and should be encouraged. We did not uncover any deleterious effects on strength, function, or fatigue. Our study documented a reduction in oxidative capacity and a blunted conditioning response to exercise possibly representing an important insight into underlying pathophysiological mechanisms. These findings also may be linked causally to mitochondrial depletion in SMA and warrant further study.

Purpose: Patients' perceptions of benefiterisk are essential to informing the regulatory process and the context in which potential therapies are evaluated. To bring this critical information to regulators, Cure SMA launched a first-ever Benefit-Risk Survey for spinal muscular atrophy (SMA) to characterize decision-making and benefiterisk trade-offs in SMA associated with a potential therapy. We hypothesized that risk tolerance would be correlated with SMA type/severity and disease progression. This article presents the results of a benefiterisk survey to enhance understanding of how patients with SMA and caregivers evaluate specific benefits and risks associated with potential therapies.Methods: Affected adults, representing all SMA types (IeIV) within the Cure SMA database, and caregivers of affected individuals of all ages/types were invited via e-mail to participate. Besteworst scaling (BWS) was used to assess participants' priorities on benefiterisk trade-offs, as it provides higher discrimination and importance scaling among tested attributes. Twelve potentially clinically meaningful treatment benefits and 11 potential risks (ranging in severity and immediacy) were tested. Multiple factors were correlated with individual responses, including: SMA type/disease severity, stage of disease, respondent type, sex, and quality of life/ level of independence (current and expected). Survey respondents were also evaluated for "risk-taking attitudes."Findings: A total of 298 responses were evaluated (28% affected adults and 72% caregivers, mostly parents). Most respondents were diagnosed >5 years ago (67.3%), with 22.1% SMA type I, 45.6% SMA type II, and 27.9% SMA type III. No strong correlation was found between risk tolerance and SMA type, stage of disease progression, respondent type, sex, quality of life assessment, or rated levels of independence. Irrespective of SMA type, respondents consistently rated the following risks, associated with a potential treatment, as "least tolerable": lifethreatening allergic reactions; 1 in 1000 risk of lifethreatening side effects leading to possible organ failure; or worsening quality of life. Furthermore, all SMA type respondents rated these risks as "most tolerable": invasive mode of treatment administration (including need for general anesthesia); side effect of dizziness; and other common side effects such as nausea, vomiting, loss of appetite, headaches, back pain, or fatigue.Implications: With the approval of the first SMA treatment, these findings offer a unique opportunity to assess and characterize baseline risk-tolerance in SMA against which to evaluate future SMA treatment options. Although differences had been expected in risk tolerance among respondents based on disease baseline and certain patient attributes, this was not observed. Survey results should inform future SMA drug development and benefiterisk assessments.