Spinal muscular atrophy (SMA) is a hereditary neurodegenerative disease with severity ranging from progressive infantile paralysis and premature death (type I) to limited motor neuron loss and normal ...life expectancy (type IV). Without disease‐modifying therapies, the impact is profound for patients and their families. Improved understanding of the molecular basis of SMA, disease pathogenesis, natural history, and recognition of the impact of standardized care on outcomes has yielded progress toward the development of novel therapeutic strategies and are summarized. Therapeutic strategies in the pipeline are appraised, ranging from SMN1 gene replacement to modulation of SMN2 encoded transcripts, to neuroprotection, to an expanding repertoire of peripheral targets, including muscle. With the advent of preliminary trial data, it can be reasonably anticipated that the SMA treatment landscape will transform significantly. Advancement in presymptomatic diagnosis and screening programs will be critical, with pilot newborn screening studies underway to facilitate preclinical diagnosis. The development of disease‐modifying therapies will necessitate monitoring programs to determine the long‐term impact, careful evaluation of combined treatments, and further acceleration of improvements in supportive care. In advance of upcoming clinical trial results, we consider the challenges and controversies related to the implementation of novel therapies for all patients and set the scene as the field prepares to enter an era of novel therapies. Ann Neurol 2017;81:355–368
To examine safety, tolerability, pharmacokinetics, and preliminary clinical efficacy of intrathecal nusinersen (previously ISIS-SMNRx), an antisense oligonucleotide designed to alter splicing of SMN2 ...mRNA, in patients with childhood spinal muscular atrophy (SMA).
Nusinersen was delivered by intrathecal injection to medically stable patients with type 2 and type 3 SMA aged 2-14 years in an open-label phase 1 study and its long-term extension. Four ascending single-dose levels (1, 3, 6, and 9 mg) were examined in cohorts of 6-10 participants. Participants were monitored for safety and tolerability, and CSF and plasma pharmacokinetics were measured. Exploratory efficacy endpoints included the Hammersmith Functional Motor Scale Expanded (HFMSE) and Pediatric Quality of Life Inventory.
A total of 28 participants enrolled in the study (n = 6 in first 3 dose cohorts; n = 10 in the 9-mg cohort). Intrathecal nusinersen was well-tolerated with no safety/tolerability concerns identified. Plasma and CSF drug levels were dose-dependent, consistent with preclinical data. Extended pharmacokinetics indicated a prolonged CSF drug half-life of 4-6 months after initial clearance. A significant increase in HFMSE scores was observed at the 9-mg dose at 3 months postdose (3.1 points; p = 0.016), which was further increased 9-14 months postdose (5.8 points; p = 0.008) during the extension study.
Results from this study support continued development of nusinersen for treatment of SMA.
This study provides Class IV evidence that in children with SMA, intrathecal nusinersen is not associated with safety or tolerability concerns.
Abstract Background ATP1A3 mutations have now been recognized in infants and children presenting with a diverse group of neurological phenotypes, including Rapid-onset Dystonia-Parkinsonism (RDP), ...Alternating Hemiplegia of Childhood (AHC), and most recently, Cerebellar ataxia, Areflexia, Pes cavus, Optic atrophy, and Sensorineural hearing loss (CAPOS) syndrome. Methods Existing literature on ATP1A3 -related disorders in the pediatric population were reviewed, with attention to clinical features and associated genotypes among those with RDP, AHC, or CAPOS syndrome phenotypes. Results While classically defined phenotypes associated with AHC, RDP, and CAPOS syndromes are distinct, common elements among ATP1A3 -related neurological disorders include characteristic episodic neurological symptoms and signs that vary in severity, duration, and frequency of occurrence. Affected children typically present in the context of an acute onset of paroxysmal, episodic neurological symptoms ranging from oculomotor abnormalities, hypotonia, paralysis, dystonia, ataxia, seizure-like episodes, or encephalopathy. Neurodevelopmental delays or persistence of dystonia, chorea, or ataxia after resolution of an initial episode are common, providing important clues for diagnosis. Conclusions The phenotypic spectrum of ATP1A3 -related neurological disorders continues to expand beyond the distinct yet overlapping phenotypes in patients with AHC, RDP, and CAPOS syndromes. ATP1A3 mutation analysis is appropriate to consider in the diagnostic algorithm for any child presenting with episodic or fluctuating ataxia, weakness or dystonia whether they manifest persistence of neurological symptoms between episodes. Additional work is needed to better identify and classify affected patients and develop targeted treatment approaches.
Nusinersen (ISIS-SMNRx or ISIS 396443) is an antisense oligonucleotide drug administered intrathecally to treat spinal muscular atrophy. We summarize lumbar puncture experience in children with ...spinal muscular atrophy during a phase 1 open-label study of nusinersen and its extension. During the studies, 73 lumbar punctures were performed in 28 patients 2 to 14 years of age with type 2/3 spinal muscular atrophy. No complications occurred in 50 (68%) lumbar punctures; in 23 (32%) procedures, adverse events were attributed to lumbar puncture. Most common adverse events were headache (n = 9), back pain (n = 9), and post–lumbar puncture syndrome (n = 8). In a subgroup analysis, adverse events were more frequent in older children, children with type 3 spinal muscular atrophy, and with a 21- or 22-gauge needle compared to a 24-gauge needle or smaller. Lumbar punctures were successfully performed in children with spinal muscular atrophy; lumbar puncture–related adverse event frequency was similar to that previously reported in children.
To report results of intrathecal nusinersen in children with later-onset spinal muscular atrophy (SMA).
Analyses included children from a phase 1b/2a study (ISIS-396443-CS2; NCT01703988) who first ...received nusinersen during that study and were eligible to continue treatment in the extension study (ISIS-396443-CS12; NCT02052791). The phase 1b/2a study was a 253-day, ascending dose (3, 6, 9, 12 mg), multiple-dose, open-label, multicenter study that enrolled children with SMA aged 2-15 years. The extension study was a 715-day, single-dose level (12 mg) study. Time between studies varied by participant (196-413 days). Assessments included the Hammersmith Functional Motor Scale-Expanded (HFMSE), Upper Limb Module (ULM), 6-Minute Walk Test (6MWT), compound muscle action potential (CMAP), and quantitative multipoint incremental motor unit number estimation. Safety also was assessed.
Twenty-eight children were included (SMA type II, n = 11; SMA type III, n = 17). Mean HFMSE scores, ULM scores, and 6MWT distances improved by the day 1,150 visit (HFMSE: SMA type II, +10.8 points; SMA type III, +1.8 points; ULM: SMA type II, +4.0 points; 6MWT: SMA type III, +92.0 meters). Mean CMAP values remained relatively stable. No children discontinued treatment due to adverse events.
Nusinersen treatment over ∼3 years resulted in motor function improvements and disease activity stabilization not observed in natural history cohorts. These results document the long-term benefit of nusinersen in later-onset SMA, including SMA type III.
NCT01703988 (ISIS-396443-CS2); NCT02052791 (ISIS-396443-CS12).
This study provides Class IV evidence that nusinersen improves motor function in children with later-onset SMA.
•NURTURE is an ongoing study of nusinersen started in a presymptomatic stage of SMA.•All infants were ≥25 months old, and alive without permanent ventilation.•All infants achieved independent sitting ...and 88% (22/25) were walking alone.•Nusinersen demonstrated durability of effect with a median 2.9 years of follow up.•Nusinersen was well tolerated with no new safety concerns over extended follow up.
Spinal muscular atrophy (SMA) is a neurodegenerative disease associated with severe muscle atrophy and weakness in the limbs and trunk. We report interim efficacy and safety outcomes as of March 29, 2019 in 25 children with genetically diagnosed SMA who first received nusinersen in infancy while presymptomatic in the ongoing Phase 2, multisite, open-label, single-arm NURTURE trial. Fifteen children have two SMN2 copies and 10 have three SMN2 copies. At last visit, children were median (range) 34.8 25.7–45.4 months of age and past the expected age of symptom onset for SMA Types I or II; all were alive and none required tracheostomy or permanent ventilation. Four (16%) participants with two SMN2 copies utilized respiratory support for ≥6 h/day for ≥7 consecutive days that was initiated during acute, reversible illnesses. All 25 participants achieved the ability to sit without support, 23/25 (92%) achieved walking with assistance, and 22/25 (88%) achieved walking independently. Eight infants had adverse events considered possibly related to nusinersen by the study investigators. These results, representing a median 2.9 years of follow up, emphasize the importance of proactive treatment with nusinersen immediately after establishing the genetic diagnosis of SMA in presymptomatic infants and emerging newborn screening efforts.
Reduction of native prion protein (PrP) levels in the brain is an attractive strategy for the treatment or prevention of human prion disease. Clinical development of any PrP-reducing therapeutic will ...require an appropriate pharmacodynamic biomarker: a practical and robust method for quantifying PrP, and reliably demonstrating its reduction in the central nervous system (CNS) of a living patient. Here we evaluate the potential of ELISA-based quantification of human PrP in human cerebrospinal fluid (CSF) to serve as a biomarker for PrP-reducing therapeutics. We show that CSF PrP is highly sensitive to plastic adsorption during handling and storage, but its loss can be minimized by the addition of detergent. We find that blood contamination does not affect CSF PrP levels, and that CSF PrP and hemoglobin are uncorrelated, together suggesting that CSF PrP is CNS derived, supporting its relevance for monitoring the tissue of interest and in keeping with high PrP abundance in brain relative to blood. In a cohort with controlled sample handling, CSF PrP exhibits good within-subject test–retest reliability (mean coefficient of variation, 13% in samples collected 8–11 wk apart), a sufficiently stable baseline to allow therapeutically meaningful reductions in brain PrP to be readily detected in CSF. Together, these findings supply a method for monitoring the effect of a PrP-reducing drug in the CNS, and will facilitate development of prion disease therapeutics with this mechanism of action.
Most children with biallelic SMN1 deletions and three SMN2 copies develop spinal muscular atrophy (SMA) type 2. SPR1NT ( NCT03505099 ), a Phase III, multicenter, single-arm trial, investigated the ...efficacy and safety of onasemnogene abeparvovec for presymptomatic children with biallelic SMN1 mutations treated within six postnatal weeks. Of 15 children with three SMN2 copies treated before symptom onset, all stood independently before 24 months (P < 0.0001; 14 within normal developmental window), and 14 walked independently (P < 0.0001; 11 within normal developmental window). All survived without permanent ventilation at 14 months; ten (67%) maintained body weight (≥3rd WHO percentile) without feeding support through 24 months; and none required nutritional or respiratory support. No serious adverse events were considered treatment-related by the investigator. Onasemnogene abeparvovec was effective and well-tolerated for presymptomatic infants at risk of SMA type 2, underscoring the urgency of early identification and intervention.
Abstract Background We identified a group of patients with ATP1A3 mutations at residue 756 who display a new phenotype, distinct from alternating hemiplegia of childhood, rapid-onset ...dystonia-parkinsonism, and cerebellar ataxia, areflexia, pes cavus, optic atrophy, sensorineural hearing loss syndromes. Methods Four patients with c.2267G>A (R756H) mutations from two families and two patients with c.2267G>T (R756L) mutations from one family are described and compared with the previously reported patients with mutations resulting in R756H and R756C protein variants. Results Patients with ATP1A3 R756H have onset in childhood of infrequent, fever-triggered paroxysms of encephalopathy and weakness with slowly improving but persistent deficits. Motor findings of weakness are mostly generalized, and patients may also have bulbar or oculomotor problems. Longer-term outcomes range from mild motor apraxia with near-normal function to persistent dysphagia, dysarthria, cognitive deficit, motor apraxia, and inability to walk because of ataxia. Patients with ATP1A3 R756L have a similar phenotype that includes paroxysmal, stepwise progression of ataxia associated with infections. Conclusions ATP1A3 mutations affecting residue 756 result in a clinical syndrome, separate from those associated with previously described ATP1A3 mutations, which consists chiefly of fever-induced paroxysmal weakness and encephalopathy (FIPWE). Patients with R756L and R756C protein variants display more prominent ataxia, overlapping with the relapsing encephalopathy with cerebellar ataxia syndrome previously described in a patient with the c.2266C>T (R756C) mutation. All patients reported with mutations at residue 756 to date have had a similar episodic course and clinical features. Patients with mutations of ATP1A3 residue 756 appear to have a distinct clinical phenotype compared with patients with other ATP1A3 mutations, with fever-induced encephalopathy as key differentiating feature.
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