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Background: Recent cost-utility analysis (CUA) models for onasemnogene abeparvovec (Zolgensma®, formerly AVXS-101) in spinal muscular atrophy type 1 (SMA1) differ on key assumptions and results. Objective: To compare the manufacturer's proprietary CUA model to the model published by the Institute for Clinical and Economic Review (ICER), and to update the manufacturer's model with long-term follow-up data and some key ICER assumptions. Study design: We updated a recent CUA evaluating value for money in cost per incremental Quality-adjusted Life Year (QALY) of onasemnogene abeparvovec versus nusinersen (Spinraza®) or best supportive care (BSC) in symptomatic SMA1 patients, and compared it to the ICER model. Setting/Perspective: USA/Commercial payer Participants: Children aged <2 years with SMA1. Interventions: Onasemnogene abeparvovec, a single-dose gene replacement therapy, versus nusinersen, an antisense oligonucleotide, versus BSC. Main outcome measure: Incremental-cost effectiveness ratio and value-based price using traditional thresholds for general medicines in the US. Results: Updated survival (undiscounted) predicted by the model was 37.60 years for onasemnogene abeparvovec compared to 12.10 years for nusinersen and 7.27 years for BSC. Updated quality-adjusted survival using ICER's utility scores and discounted at 3% were 13.33, 2.85, and 1.15 discounted QALYs for onasemnogene abeparvovec, nusinersen, and BSC, respectively. Using estimated net prices, the discounted lifetime cost/patient was $3.93 M for onasemnogene abeparvovec, $4.60 M for nusinersen, and $1.96 M for BSC. The incremental cost per QALY gained for onasemnogene abeparvovec was dominant against nusinersen and $161,648 against BSC. These results broadly align with the results of the ICER model, which predicted a cost per QALY gained of $139,000 compared with nusinersen, and $243,000 compared with BSC (assuming a placeholder price of $2 M for onasemnogene abeparvovec), differences in methodology notwithstanding. Exploratory analyses in presymptomatic patients were similar. Conclusion: This updated CUA model is similar to ICER analyses comparing onasemnogene abeparvovec with nusinersen in the symptomatic and presymptomatic SMA populations. At a list price of $2.125 M, onasemnogene abeparvovec is cost-effective compared to nusinersen for SMA1 patients treated before age 2 years. When compared to BSC, cost per QALY of onasemnogene abeparvovec is higher than commonly used thresholds for therapies in the USA ($150,000 per QALY). [ABSTRACT FROM AUTHOR]

Background: Spinal muscular atrophy type 1 (SMA1) is a devastating genetic disease for which gene-replacement therapy may bring substantial survival and quality of life benefits. Objective: This study investigated the cost-effectiveness of onasemnogene abeparvovec (AVXS-101) gene-replacement therapy for SMA1. Study design: A Markov model was used to estimate the incremental cost-effectiveness ratio (ICER), expressed as cost/quality-adjusted life year ($/QALY), of AVXS-101 versus nusinersen over a lifetime. Survival, healthcare costs and QALYs were estimated using natural history data for SMA patients who achieved motor milestones (sitting/walking). Health utility weights were obtained from the CHERISH trial. Setting: USA; commercial payer perspective Participants: SMA1 infants Interventions: AVXS-101 was compared to nusinersen. Main outcome measure: The primary outcome was the ICER. Results: Expected survival (undiscounted) over a lifetime predicted by the model was 37.20 life years for AVXS-101 and 9.68 for nusinersen (discounted QALYs, 15.65 and 5.29, respectively). Using a potential AVXS-101 price range ($2.5-5.0M/treatment), the average lifetime cost/patient was $4.2–6.6M for AVXS-101 and $6.3M for nusinersen. The ICER range was (-$203,072) to $31,379 per QALY gained for AVXS-101 versus nusinersen, indicating that AVXS-101 was cost-effective with prices of ≤$5M. Conclusion: Single-dose AVXS-101 was cost-effective compared to chronic nusinersen for SMA1 patients. [ABSTRACT FROM AUTHOR]

As part of a natural history study of giant axonal neuropathy, we hypothesized that the Friedreich Ataxia Rating Scale and the Gross Motor Function Measure would show a significant change over 6 months, reflecting subjects’ decline in motor function. The Friedreich Ataxia Rating Scale was performed on 11 subjects and the Gross Motor Function Measure was performed on 10 subjects twice with a six-month interval. A paired two-tailed t-test was used to assess the difference in each subject’s score. Significant changes were found over six months of 11.7 ± 11.0 (P = 0.006) for the Friedreich Ataxia Rating Scale and –10.0 ± 13.5 (P = 0.043) for the Gross Motor Function Measure, reflecting subjects’ decline in motor function on examination and by report. These standardized assessments of clinical function are the first to be validated in giant axonal neuropathy and will be used in an upcoming gene therapy clinical trial. [ABSTRACT FROM PUBLISHER]

Spinal muscular atrophy is an autosomal recessive neurodegenerative disease caused by homozygous mutation to the survival motor neuron 1 (SMN1) gene. Historically, spinal muscular atrophy has been considered to almost exclusively affect the function and survival of alpha motor neurons of the spinal cord and brainstem. With the development of animal models of spinal muscular atrophy, the presence of widespread systemic abnormalities affecting the brain, heart, and pancreas has been repeatedly noted among animals with diminished survival motor neuron protein expression. While these observations suggest similar possible effects in humans, reports of primary systemic disease manifestations among humans affected by spinal muscular atrophy are strikingly lacking. Here we report a case of a 29-year-old man with genetically confirmed spinal muscular atrophy type II who presented with new onset diabetes mellitus and diabetic ketoacidosis. [ABSTRACT FROM AUTHOR]

Weakness and fatigue are captured by the 6-minute walk test, but the relationship between these symptoms is uncertain. Comparison across neuromuscular diseases has not been examined. A cohort study of 114 patients with spinal muscular atrophy, Duchenne/Becker muscular dystrophy, myasthenia gravis, and energy failure syndromes were included. Percent-predicted distance on the 6-minute walk test was computed from normative values to determine weakness. Fatigue was determined by the decrement in distance from the first to sixth minute. Weakness was seen across all groups (61.9%) but significant fatigue was seen only in spinal muscular atrophy (21.0%). Other groups showed little fatigue. Correlation between weakness and fatigue was significant only in spinal muscular atrophy (R = –0.71; P < .001). Longitudinally, distance walked declined only in Duchenne/Becker muscular dystrophy. In spinal muscular atrophy, weakness did not change, but fatigue increased significantly. These findings suggest independent mechanisms underlying weakness and fatigue in diverse neuromuscular conditions. [ABSTRACT FROM PUBLISHER]

Weakness resulting from spinal muscular atrophy causes severe limitations in functional mobility. The early introduction of power mobility has potential to enhance development and mitigate disability. These outcomes are achieved by simulating normal skill acquisition and by promoting motor learning, visuospatial system development, self-exploration, cognition, and social development. There are few reports on early power mobility in spinal muscular atrophy, and it is typically not prescribed until school age. The authors evaluated 6 children under age 2 years with neuromuscular disease (5 spinal muscular atrophy, 1 congenital muscular dystrophy) for power mobility. Parents recorded the practice hours necessary to achieve independence using the Power Mobility Skills Checklist. Four children achieved independence in all items on the checklist by 7.9 months (range: 73-458 days). Introduction of early power mobility is feasible in spinal muscular atrophy patients under age 2 years and should be introduced in late infancy when children typically acquire locomotor skills. [ABSTRACT FROM AUTHOR]

Objectives: Spinal Muscular Atrophy (SMA) presents challenges in (i) monitoring disease activity and predicting progression, (ii) designing trials that allow rapid assessment of candidate therapies, and (iii) understanding molecular causes and consequences of the disease. Validated biomarkers of SMA motor and non-motor function would offer utility in addressing these challenges. Our objectives were (i) to discover additional markers from the Biomarkers for SMA (BforSMA) study using an immunoassay platform, and (ii) to validate the putative biomarkers in an independent cohort of SMA patients collected from a multi-site natural history study (NHS). Methods: BforSMA study plasma samples (N = 129) were analyzed by immunoassay to identify new analytes correlating to SMA motor function. These immunoassays included the strongest candidate biomarkers identified previously by chromatography. We selected 35 biomarkers to validate in an independent cohort SMA type 1, 2, and 3 samples (N = 158) from an SMA NHS. The putative biomarkers were tested for association to multiple motor scales and to pulmonary function, neurophysiology, strength, and quality of life measures. We implemented a Tobit model to predict SMA motor function scores. Results: 12 of the 35 putative SMA biomarkers were significantly associated (p<0.05) with motor function, with a 13th analyte being nearly significant. Several other analytes associated with non-motor SMA outcome measures. From these 35 biomarkers, 27 analytes were selected for inclusion in a commercial panel (SMA-MAP) for association with motor and other functional measures. Conclusions: Discovery and validation using independent cohorts yielded a set of SMA biomarkers significantly associated with motor function and other measures of SMA disease activity. A commercial SMA-MAP biomarker panel was generated for further testing in other SMA collections and interventional trials. Future work includes evaluating the panel in other neuromuscular diseases, for pharmacodynamic responsiveness to experimental SMA therapies, and for predicting functional changes over time in SMA patients. [ABSTRACT FROM AUTHOR]

Growth failure is nearly universal in spinal muscular atrophy type 1 and common in type 2, although acuity is often underappreciated at initial diagnosis. We reviewed 44 consecutive spinal muscular atrophy patients (28 type 1, 16 type 2) under 3 years at initial presentation. Growth failure was conventionally defined: weight below the fifth percentile or dropping 2 major percentiles over 6 months. Growth failure differed among subjects stratified by age at disease onset using the Kaplan-Meier method (P = 0.011). Median time to growth failure among subjects with onset between 0 to 3 months of age was 5 months; Only 1 of 22 avoided failure by 22 months of age. Median time to failure with disease onset between 4 to 6 months was 15 months. Most late onset (> 6 months) subjects avoided growth failure. Early clinical symptoms predict feeding dysfunction and growth failure. Immediate, proactive nutritional intervention is indicated for patients with early symptom onset. [ABSTRACT FROM AUTHOR]

Spinal muscular atrophy is a relatively stable chronic disease. Patients may gradually experience declines in muscle strength and motor function over time. However, functional progression is difficult to document, and the mechanism remains poorly understood. An 11-year-old girl was diagnosed at 19 months and took a few steps without assistance at 25 months. She was evaluated for 54 months in a prospective multicenter natural history study. Outcome measures were performed serially. From 6 to 7.5 years, motor function improved. From 7.5 to 11 years, motor function declined with increasing growth. Manual muscle testing scores minimally decreased. Motor unit number estimation studies gradually increased over 4.5 years. Compared to the published natural history of spinal muscular atrophy type III, our patient lost motor function over time. However, she walked with assistance 2 years longer than expected. Our report highlights possible precipitating factors that could affect the natural history of spinal muscular atrophy type III. [ABSTRACT FROM PUBLISHER]

Changes in thigh muscle volume over 6 months were assessed using magnetic resonance imaging in 11 subjects aged 6 to 47 years with spinal muscular atrophy (4 type 2 and 7 type 3; 4 ambulatory and 3 nonambulatory). Muscle volume with normal and abnormal signal was measured using blinded, semiautomated analysis of reconstructed data. Volumes at baseline and 6 months were correlated with clinical function at each epoch. There was minimal increase in normal (0.3 ± 1.4 mL/cm) and total (0.1 ± 1.3 mL/cm) muscle. Muscle volume correlated closely with clinical function. Minimal interval change in muscle volume is consistent with the established clinical history of minimal disease progression over intervals shorter than 1 year. Relative constancy of muscle volume estimation and correlation with established functional measures suggest a role for segmental magnetic resonance imaging as a biomarker of treatment effect in future therapeutic trials. [ABSTRACT FROM AUTHOR]

Thigh muscle volume was assessed using magnetic resonance imaging in 16 subjects with spinal muscular atrophy. Scans were successful for 14 of 16 subjects (1 type 1, 6 type 2, and 7 type 3) as young as 5.7 years. Muscle volume with normal and abnormal signal was measured using blinded, semiautomated analysis of reconstructed data. Results were compared with segmental lean mass estimated by dual-energy X-ray absorptiometry and correlated with clinical and electrophysiological measures of disease severity. Muscle volume was reduced with abnormal signal quality. Test-retest reliability (r = .99) and correlation with dual-energy X-ray absorptiometry (r = .91) were excellent. Type 2 subjects had lower volume (3.5 ± 1.6 vs 6.3 ± 2.8 mL/cm height; P = .06) and higher percentage of muscle with abnormal signal (68% ± 20% vs 47% ± 27%; P = .14) than type 3. Reproducibility, tolerability, and strong correlation with clinical measures make magnetic resonance imaging a candidate biomarker for clinical research. [ABSTRACT FROM AUTHOR]

Accurate, noninvasive measures of body composition are needed for management of patients with spinal muscular atrophy. Fat mass index (fat mass/height2 in kg/m2) was measured in 16 subjects with spinal muscular atrophy using 5 bioelectrical impedance analysis equations and compared with a reference method, dual-energy x-ray absorptiometry. The machine default equation, validated by Cordain, was the primary analysis. Fat mass index calculated by impedance measures differed by between -2.5 kg/m2 and 1.7 kg/m2 from the reference mean (8.3 ± 5.0 kg/m2). The Cordain equation provided the smallest difference (-0.4 ± 2.0 kg/m2), with correlation coefficient of 0.92. The Cordain equation showed high sensitivity (85.7%) and specificity (100%) for prediction of ‘‘at risk for overweight’’ (fat mass index > 85th percentile for age and gender). Although insufficiently accurate for use as a research tool, bioelectrical impedance can have application as a well-tolerated, noninvasive, easily used screening tool for excess adiposity in patients with spinal muscular atrophy. [ABSTRACT FROM PUBLISHER]

Spinal muscular atrophy (SMA), a potentially devastating disease marked by progressive weakness and muscle atrophy resulting from the dysfunction and loss of motor neurons of the spinal cord, has emerged in recent years as an attractive target for therapeutic intervention. Caused by a homozygous mutation to the Survival of Motor Neurons 1 (SMN1) gene on chromosome 5q, the severity of the clinical phenotype in SMA is modulated by the function of a related protein, Survival of Motor Neurons 2 (SMN2). SMN2 predominantly produces an unstable SMN transcript lacking exon 7; only about 10% of the transcription product produces a full-length, functional SMN protein. Several therapeutic strategies have targeted this gene with the goal of producing increased full-length SMN transcript, thereby modifying the underlying mechanism. Drugs that have increased SMN2 function, in vitro, are now explored for potential therapeutic benefit in this disease. Alternative approaches, including neuroprotective, muscle anabolic, gene and cell replacement strategies, also hold promise. The recent advances in preclinical research and the development of a wider range of animal models for SMA continue to provide cautious optimism that effective treatments for SMA will eventually emerge. [ABSTRACT FROM PUBLISHER]

Background: This study characterizes motor function responses after early dosing of AVXS-101 (onasemnogene abeparvovec) in gene replacement therapy in infants with severe spinal muscular atrophy type 1 (SMA1).Methods: This study is a follow-up analysis of 12 infants with SMA1 who received the proposed therapeutic dose of AVXS-101 in a Phase 1 open-label study (NCT02122952). Infants were grouped according to age at dosing and baseline Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders scores: (1) early dosing/low motor, dosed age less than three months with scores <20 (n = 3), (2) late dosing, dosed at age three months or greater (n = 6), and (3) early dosing/high motor, dosed age less than three months with scores ≥20 (n = 3).Results: Early dosing/low motor group demonstrated a mean gain of 35.0 points from a mean baseline of 15.7, whereas the late dosing group had a mean gain of 23.3 from a mean baseline of 26.5. The early dosing/high motor group quickly reached a mean score of 60.3, near the scale maximum (64), from a mean baseline of 44.0. Despite a lower baseline motor score, the early dosing/low motor group achieved sitting unassisted earlier than the late dosing group (mean age: 17.0 vs 22.0 months). The early dosing/high motor group reached this milestone earliest (mean age: 9.4 months).Conclusions: The rapid, significant motor improvements among infants with severe SMA1 treated with AVXS-101 at an early age highlight the importance of newborn screening and early treatment and demonstrate the therapeutic potential of AVXS-101 regardless of baseline motor function. [ABSTRACT FROM AUTHOR]

Background: Spinal muscular atrophy type 1 (SMA1) is the leading genetic cause of infant mortality for which therapies, including AVXS-101 (onasemnogene abeparvovec, Zolgensma®) gene replacement therapy, are emerging., Objective: This study evaluated the effectiveness of AVXS-101 in infants with spinal muscular atrophy type 1 (SMA1) compared with a prospective natural history cohort and a cohort of healthy infants., Methods: Twelve SMA1 infants received the proposed therapeutic dose of AVXS-101 (NCT02122952). Where possible, the following outcomes were compared with a natural history cohort of SMA1 infants (n = 16) and healthy infants (n = 27) enrolled in the NeuroNEXT (NN101) study (NCT01736553): event-free survival, CHOP-INTEND scores, motor milestone achievements, compound muscle action potential (CMAP), and adverse events., Results: Baseline characteristics of SMA1 infants in the AVXS-101 and NN101 studies were similar in age and genetic profile. The proportion of AVXS-101-treated infants who survived by 24 months of follow-up was higher compared with the NN101 study (100% vs 38%, respectively). The average baseline CHOP-INTEND score for NN101 SMA1 infants was 20.3, worsening to 5.3 by age 24 months; the average baseline score in AVXS-101-treated infants was 28.2, improving to 56.5 by age 24 months. Infants receiving AVXS-101 achieved motor milestones, such as sitting unassisted and walking. Improvements in CMAP peak area were observed in AVXS-101-treated infants at 6 and 24 months (means of 1.1 and 3.2 mV/s, respectively)., Conclusions: In this study, AVXS-101 increased the probability of survival, rapidly improved motor function, and enabled motor milestone achievement in SMA1 infants.