Trials In Spinal Muscular Atrophy Research Articles

Gain and loss of abilities in type II SMA: A 12-month natural history study

The advent of clinical trials in spinal muscular atrophy (SMA) has highlighted the need to define patterns of progression using functional scales. It has recently been suggested that the analysis of abilities gained or lost applied to functional scales better reflects meaningful changes. We defined as “gain” a positive change between scores from 0 to either 1 or 2 and as “loss” a negative change from either 2 or 1 to 0. The aim of this study was to describe, over 12 months, which abilities on the Hammersmith Functional Motor Scale Expanded (HFMSE) were more frequently lost or gained in patients with SMA II. The cohort included 614 12-month assessments from 243 patients (age range: 30 months - 63 years; mean 9.94, SD ±7.91). The peak of abilities gained occurred before the age of 5 years while the highest number of lost abilities was found in the group 5–13 years. A correlation between the HFMSE baseline score and the ordinal number of the items was found for both lost (p<0.001) or gained (p<0.001) activities. No correlation was found with SMN2 copy number. These findings will have implications for clinical trial design and for the interpretation of real-world data using new therapeutic approaches.

Heritable Genome Editing: Who Speaks for "Future" Children?

Approximately 80% of rare and often incurable and serious conditions affect newborns and children, and roughly half of all rare diseases are considered to have an onset in childhood. Somatic gene therapies are already in clinical trials for spinal muscular atrophy, beta thalassemia, and macular degeneration. If proven to be safe and effective, could heritable genome editing be seen as a form of preventive personalized medicine and as fostering the right to health of the child? The latest calls for global moratoria on clinical applications of heritable genome editing are troubling in that they may create an illusion of control over rogue science and stifle the necessary international debate surrounding an ethically responsible translational path forward. Children are people with distinct rights and interests. An arbitrary moratorium neither fosters their best interests or health nor respects their right to benefit from the advancements of science.

Morpholino-Mediated Exon Inclusion for SMA.

The application of antisense oligonucleotides (AONs) to modify pre-messenger RNA splicing has great potential for treating genetic diseases. The strategies used to redirect splicing for therapeutic purpose involve the use of AONs complementary to splice motifs, enhancer or silencer sequences. AONs to block intronic splicing silencer motifs can efficiently augment exon 7 inclusion in survival motor neuron 2 (SMN2) gene and have demonstrated robust therapeutic effects in both preclinical studies and clinical trials in spinal muscular atrophy (SMA), which has led to a recently approved drug. AONs with phosphorodiamidate morpholino oligomer(PMO) backbone have shown target engagement with restoration of the defective protein in Duchenne muscular dystrophy (DMD) and their safety profile lead to a recent conditional approval for one DMD PMO drug. PMO AONs are also effective in correcting SMN2 exon 7 splicing and rescuing SMA transgenic mice. Here we provide the details of methods that our lab has used to evaluate PMO-mediated SMN2 exon 7 inclusion in the in vivo studies conducted in SMA transgenic mice. The methods comprise mouse experiment procedures, assessment of PMOs on exon 7 inclusion at RNA levels by reverse transcription (RT-) PCR and quantitative real-time PCR. In addition, we present methodology for protein quantification using western blot in mouse tissues, on neuropathology assessment of skeletal muscle (muscle pathology and neuromuscular junction staining) as well as behaviour test in the SMA mice (righting reflex).

1825 Anti-sense treatment in sma: a landmark in the therapy of motor neuron diseases

Despite significant advances in basic research, the treatment of degenerative diseases of the nervous system remains one of the greatest challenges for translational medicine. The childhood onset motor neuron disorder spinal muscular atrophy (SMA) has been viewed as one of the more tractable targets for molecular therapy, due to our detailed understanding of the molecular genetic basis of the disease. In SMA, inactivating mutations in the SMN1 gene can be partially compensated for by limited expression of SMN protein from a variable number of copies of the SMN2 gene, which provides both a molecular explanation for phenotypic severity and a target for therapy. The advent of the first tailored molecular therapy for SMA, nusinersin, based on modulating the splicing behaviour of the SMN2 gene, is the first treatment which significantly alters the natural history of motor neuron degeneration. This will change the landscape for diagnosis, clinical management and future therapeutic trials in SMA, and has implications for the molecular therapy of other neurological diseases.

S06 - Experimental trials in spinal muscular atrophy

S06 - Experimental trials in spinal muscular atrophy

362. Translatable Gene Therapy for Infantile Neuronal Lipofuscinosis

Infantile Neuronal Ceroid Lipofuscinosis (INCL) is a rare lysosomal storage disease caused by mutations in the CLN1 gene, which encodes the protein palmitoyl-protein thioesterase-1 (PPT1). In the absence of the PPT1 enzyme, osmiophilic granules accumulate in cells, eventually leading to cell dysfunction and neurodegeneration. In the classic form in human patients, the damage from the storage material and resulting cell death causes visual failure, speech and motor deterioration, and seizures to appear between the ages of 6 and 24 months, with premature death, usually between 3 to 5 years of age. INCL mice (CLN1 knock-out) accurately model the disease symptoms and pathogenesis, leading to premature death at approximately 8 months of age. Previous results from Mark Sands’ laboratory have shown that intracranial administration of AAV5 vectors in newborn INCL mice results in a significant extension of lifespan of approximately 50% along with improvements in motor function. While encouraging, the translation of this approach in humans is complicated by the reduced relative biodistribution of the vector after intracranial administration when moving from a rodent to human brain, and because a newborn mouse corresponds to a prenatal time period in humans. With the ability of AAV9 to cross the blood-brain barrier, intravenous (IV) administration of the vector can achieve widespread distribution of the transgene in the Central Nervous System (CNS), while intrathecal (IT) administration of AAV9 vectors into the cerebrospinal fluid (CSF) can achieve a similar CNS distribution at a considerably lower dose more amenable to human translation. Currently, self-complementary AAV9 vectors are being used in ongoing Phase I human clinical trials for Spinal Muscular Atrophy, administered IV (NCT02122952), and for Giant Axonal Neuropathy, administered IT (NCT02122952). We have pursued two global and translationally-relevant gene transfer approaches for INCL: IT delivery of scAAV9/CLN1 into the CSF of the lumbar cistern at a dose of 7×1010 vg per mouse, and IV delivery of scAAV9.47/CLN1, a liver-detargeted vector, at a dose of 1×1012 vg per mouse. Both approaches were evaluated at different ages: 1 week and 4 weeks (pre-symptomatic), 20 weeks (early-symptomatic) and 26 weeks (post-symptomatic). While we failed to rescue mice injected at 20 weeks or later, mice treated at 1 and 4 weeks of age increased their survival to approximately twice their expected lifespan (ongoing), concurrent with improvement of their quality of life. These results will be compared to a cohort of mice injected as neonates, which are alive at 1 year and being monitored for long-term benefits. Our results indicate that, at the current doses, either treatment approach is effective early in the disease course, providing a dramatic survival benefit and improved quality of life, but it is wholly ineffective once significant symptoms have emerged. The IT route offers a comparable rescue at < 1/10 the dose, making this approach potentially more favorable for human translation. We propose this as a realistic and readily translatable approach to treat INCL.

The influence of storage parameters on measurement of survival motor neuron (SMN) protein levels: Implications for pre-clinical studies and clinical trials for spinal muscular atrophy

Spinal muscular atrophy (SMA) is caused by low levels of survival motor neuron (SMN) protein. A growing number of potential therapeutic strategies for SMA are entering pre-clinical and clinical testing, including gene therapy and antisense oligonucleotide-based approaches. For many such studies SMN protein levels are used as one major readout of treatment efficacy, often necessitating comparisons between samples obtained at different times and/or using different protocols. Whether differences in tissue sampling strategies or storage parameters have an influence on measurable SMN levels remains to be determined. We assessed murine SMN protein immunoreactivity over time and under differing tissue storage conditions. SMN protein levels, measured using sensitive quantitative fluorescent western blotting, declined rapidly over a period of several days following sample collection, especially when protein was extracted immediately and stored at −20°C. Storage of samples at lower temperatures (−80°C), and as intact tissue, led to significantly better preservation of SMN immunoreactivity. However, considerable deterioration in measurable SMN levels occurred, even under optimal storage conditions. These issues need to be taken into consideration when designing and interpreting pre-clinical and clinical SMA studies where SMN protein levels are being measured.

SMA-EUROPE workshop report: opportunities and challenges in developing clinical trials for spinal muscular atrophy in Europe

Spinal muscular atrophy (SMA) is the most common lethal recessive disease in childhood, and there is currently no effective treatment to halt disease progression. The translation of scientific advances into effective therapies is hampered by major roadblocks in clinical trials, including the complex regulatory environment in Europe, variations in standards of care, patient ascertainment and enrolment, a narrow therapeutic window and a lack of biomarkers of efficacy. In this context, SMA-Europe organized its first international workshop in July 2012 in Rome, gathering 34 scientists, clinicians and representatives of patient organizations to establish recommendations for improving clinical trials for SMAa.

Spinal muscular atrophy at the crossroads of basic science and therapy

The 8th annual UK spinal muscular atrophy (SMA) Dr. Eduardo Tizzano (Hospital de Santa Creu i Sant research conference, jointly organised and sponsored by the SMA Trust and the Jennifer Trust for SMA, was held onOctober 3–4, 2011 inOxford, UK.Hosted by Prof. Kevin Talbot at the Oxford Belfry Hotel, the meeting was attended by over 40 researchers and clinicians from across Europe and a total of 17 platform presentations were given. The first day of talks provided a new perspective on the basic functions of the survival motor neuron (SMN) protein, challenged the general assumption that SMA is simply a disorder of the lower motor neuron, and provided interesting ideas on the cause of motor neuron specificity seen in the disease; the second day concentrated on practical aspects of clinical trials in SMA and explored some emerging therapies that are at the cusp of translation to human trials. Presentations on the first day were given by Prof. Michael Sendtner (University of Wurzburg, Germany) on a neuronal specific function of SMN, Dr. Thomas Wishart (University of Edinburgh, UK) on SMN protein expression at the synapse, Dr. Zameel Cader (University of Oxford, UK) on a non-cell autonomous mechanism of neuronal toxicity in distal SMA type V, Dr. Judith Sleeman (University of St. Andrews, UK) on small nuclear ribonucleoprotein dynamics and splicing, Prof. Thomas Gillingwater (University of Edinburgh, UK) on the differential susceptibility of tissues to SMN depletion, Dr. Simon Parson (University of Edinburgh, UK) on the microvasculature in a severe mouse model of SMA, Miss. Maria Gabriela Boza-Moran (University of London, UK) on using stem cells to elucidate pathological mechanisms of SMA, Dr. Heidi Fuller (Keele University, UK) on the proteomic effects of salbutamol treatment on SMA fibroblasts, and

SMA CARNI-VAL TRIAL PART II: A Prospective, Single-Armed Trial of L-Carnitine and Valproic Acid in Ambulatory Children with Spinal Muscular Atrophy

BackgroundMultiple lines of evidence have suggested that valproic acid (VPA) might benefit patients with spinal muscular atrophy (SMA). The SMA CARNIVAL TRIAL was a two part prospective trial to evaluate oral VPA and l-carnitine in SMA children. Part 1 targeted non-ambulatory children ages 2–8 in a 12 month cross over design. We report here Part 2, a twelve month prospective, open-label trial of VPA and L-carnitine in ambulatory SMA children.MethodsThis study involved 33 genetically proven type 3 SMA subjects ages 3–17 years. Subjects underwent two baseline assessments over 4–6 weeks and then were placed on VPA and L-carnitine for 12 months. Assessments were performed at baseline, 3, 6 and 12 months. Primary outcomes included safety, adverse events and the change at 6 and 12 months in motor function assessed using the Modified Hammersmith Functional Motor Scale Extend (MHFMS-Extend), timed motor tests and fine motor modules. Secondary outcomes included changes in ulnar compound muscle action potential amplitudes (CMAP), handheld dynamometry, pulmonary function, and Pediatric Quality of Life Inventory scores.ResultsTwenty-eight subjects completed the study. VPA and carnitine were generally well tolerated. Although adverse events occurred in 85% of subjects, they were usually mild and transient. Weight gain of 20% above body weight occurred in 17% of subjects. There was no significant change in any primary outcome at six or 12 months. Some pulmonary function measures showed improvement at one year as expected with normal growth. CMAP significantly improved suggesting a modest biologic effect not clinically meaningful.ConclusionsThis study, coupled with the CARNIVAL Part 1 study, indicate that VPA is not effective in improving strength or function in SMA children. The outcomes used in this study are feasible and reliable, and can be employed in future trials in SMA.Trial RegsitrationClinicaltrials.gov NCT00227266

Genotype–phenotype studies in infantile spinal muscular atrophy (SMA) type I in Germany: implications for clinical trials and genetic counselling

We reviewed the natural history and assessed the SMN2 copy number of 66 patients with infantile spinal muscular atrophy (SMA) type I born between 2000 and 2005 in Germany whose diagnosis was confirmed by a homozygous SMN1 deletion in the first 6 months of life. After excluding patients who had received valproic acid, the median/mean age at disease endpoint was 6.1/7.3 months (range 0.0-34.0). Four (6.1%) patients with one SMN2 copy had severe SMA type '0' with joint contractures and respiratory distress from birth. Median/mean age at onset (months) in 57 (86.3%) patients with two SMN2 copies was 1.2/1.3, and 3.5/3.4 in 5 (7.6%) patients with three SMN2 copies. Median/mean age at disease endpoint was 6.5/7.8 months (range 0.5-30) in patients with two SMN2 copies. All patients with three SMN2 copies were still alive at 10-55 months, two of them under permanent ventilation. Our data are relevant for prognostication and genetic counselling. The observed clinical variability, especially in the group with two SMN2 copies, might be important for clinical trials in SMA I where a possible control group could be defined as follows: age at onset within 4-5 months, age at genetic diagnosis <6 months, two SMN2 copies present, head control in less than 10%, no respiratory distress from birth, disease endpoint either age at death or age at permanent ventilation.

Towards harmonisation of outcome measures for DMD and SMA within TREAT-NMD; Report of three expert workshops: TREAT-NMD/ENMC Workshop on outcome measures, 12th–13th May 2007, Naarden, The Netherlands; TREAT-NMD Workshop on outcome measures in experimental trials for DMD, 30th June–1st July 2007, Naarden, The Netherlands; Conjoint Institute of Myology TREAT-NMD Meeting on physical activity monitoring in neuromuscular disorders, 11th July 2007,

Towards harmonisation of outcome measures for DMD and SMA within TREAT-NMD; Report of three expert workshops: TREAT-NMD/ENMC Workshop on outcome measures, 12th–13th May 2007, Naarden, The Netherlands; TREAT-NMD Workshop on outcome measures in experimental trials for DMD, 30th June–1st July 2007, Naarden, The Netherlands; Conjoint Institute of Myology TREAT-NMD Meeting on physical activity monitoring in neuromuscular disorders, 11th July 2007, Paris, France

Clinical trials in spinal muscular atrophy

Spinal muscular atrophy is a neuromuscular disorder manifesting as weakness and hypotonia across a broad spectrum of severity. Mutations in the telomeric copy of the survival motor neuron gene (SMN1) cause the autosomal recessive form. Disease severity is modified by the number of centromeric copies of the gene (SMN2) and the quantity of survival motor neuron protein. This has given rise to a number of treatment strategies. Histone deacetylase inhibitors appear to increase the expression of SMN2, with an increase in survival motor neuron protein in various cell types. Clinical trials have been performed with three histone deacetylase inhibitors which are already licensed in the USA. Phenylbutyrate showed promise in a mouse model and an open-label pilot study, but was not effective in a phase 2 trial. Valproate may enhance transcription and reverse SMN2 splicing pattern, and has induced promising motor-function improvement in patients. Hydroxyurea may enhance splice function and increase the number of nuclear 'gems', small nuclear organelles in which survival motor neuron protein concentrates. Discoveries regarding the genetics and pathogenesis of spinal muscular atrophy have identified potential targets for pharmacotherapy, raising hope that better treatments will eventually be developed.

Perspectives on Clinical Trials in Spinal Muscular Atrophy

Spinal muscular atrophy is one of the most heterogeneous of the single-gene neuromuscular disorders. The broad spectrum of severity, with onset from the prenatal period to adulthood, presents unique challenges in the design and implementation of clinical trials. The clinical classification of subjects into severe (type 1), intermediate (type 2), and mild (type 3) subtypes has proved useful both in enhancing communication among clinicians internationally and in forging the collaborative development of outcome measures for clinical trials. Ideally, clinical trial design in spinal muscular atrophy must take into account the spinal muscular atrophy type, patient age, severity-of-affection status, nature of the therapeutic approach, timing of the proposed intervention relative to disease progression, and relative homogeneity of the cohort to be studied. Following is an overview of the challenges and opportunities, current and future therapeutic strategies, and progress to date in clinical trials in spinal muscular atrophy.

SMN mRNA and protein levels in peripheral blood

Clinical trials of drugs that increase SMN protein levels in vitro are currently under way in patients with spinal muscular atrophy. To develop and validate measures of SMN mRNA and protein in peripheral blood and to establish baseline SMN levels in a cohort of controls, carriers, and patients of known genotype, which could be used to follow response to treatment. SMN1 and SMN2 gene copy numbers were determined in blood samples collected from 86 subjects. Quantitative reverse transcription PCR was used to measure blood levels of SMN mRNA with and without exon 7. A cell immunoassay was used to measure blood levels of SMN protein. Blood levels of SMN mRNA and protein were measured with high reliability. There was little variation in SMN levels in individual subjects over a 5-week period. Levels of exon 7-containing SMN mRNA and SMN protein correlated with SMN1 and SMN2 gene copy number. With the exception of type I SMA, there was no correlation between SMN levels and disease severity. SMN mRNA and protein levels can be reliably measured in the peripheral blood and used during clinical trials in spinal muscular atrophy, but these levels do not necessarily predict disease severity.

Challenges and opportunities in clinical trials for spinal muscular atrophy

Spinal muscular atrophy (SMA) is the most common fatal neuromuscular disease of infancy. SMA type I is the most severe and mortality is usually due to respiratory failure. In type II the disability is of later onset and less severe, and prognosis has improved primarily due to supportive care. Type III is the mildest form with onset usually of weakness in adolescence or young adulthood. SMA is an autosomal recessive disorder with deletions or mutations of the gene at the 5 q11 locus. There is no specific prevention or treatment, but current progress toward potential therapies has been substantial and several candidates including histone deacetylase (HDAC) inhibitors are under consideration for further evaluation. The authors sought to address the challenges and opportunities for testing new therapies for SMA.

A placebo-controlled trial of gabapentin in spinal muscular atrophy

Objective: To evaluate the efficacy of gabapentin in increasing muscle strength of patients with spinal muscular atrophy (SMA). Background: Preclinical data in experimental models of motor neuron disease suggest a neuroprotective effect of gabapentin. Methods: Gabapentin (1200 mg), or placebo, was administered three times daily in a randomized, double-blind trial for 12 months. The primary outcome measure was the average percent change from baseline, based on the measurement of strength in four muscles (elbow flexion and hand grip bilaterally) for each patient. Drug efficacy was examined by comparing the percent change in strength for patients on drug vs. placebo. Secondary efficacy variables included: forced vital capacity (FVC), SMA functional rating scale (SMAFRS), and mini-Sickness Impact Profile (SIP). Results: Eighty-four patients, with type II or III SMA, were enrolled at eight sites across the United States. There were no differences in baseline features. There was no difference between the placebo and drug groups in any outcome measure. Conclusions: This study demonstrates the feasibility of this trial design and provides data for the design of future clinical trials in SMA.

Prospective analysis of strength in spinal muscular atrophy. DCN/Spinal Muscular Atrophy Group.

Spinal muscular atrophy is a genetic disorder of the motor neurons that causes profound hypotonia, severe weakness, and often fatal restrictive lung disease. Patients with spinal muscular atrophy present a spectrum of disease from the most severe infantile-onset type, called Werdnig-Hoffmann disease (type 1), associated with a mortality rate of up to 90%, to a late-onset mild form (type 3), wherein patients remain independently ambulatory throughout adult life. Although many clinicians agree that patients with spinal muscular atrophy lose motor abilities with age, it is unknown whether progressive weakness occurs in all patients with spinal muscular atrophy. We present here results of the first prospective study of muscle strength in patients with spinal muscular atrophy. There was no loss in muscle strength as determined by a quantitative muscle test during the observation period. However, motor function diminished dramatically in some patients with spinal muscular atrophy. Explanations for this loss of function could not be determined from our data. Decrease in motor function could be caused by factors other than loss of strength. Therefore, it is not clear from our results whether spinal muscular atrophy is a neurodegenerative disease. We conclude that treatment trials in spinal muscular atrophy should be designed with consideration of the natural history of strength and motor function in this disorder.

Carrell-Krusen Symposium invited lecture. Clinical trials in motor neuron diseases.

Although there is no truly effective disease-specific therapy for any of the motor neuron diseases, rapid progress in our understanding of the pathophysiology of some of these disorders is being made. In addition to progress in neuroscience, clinical trials of agents that appear to slow the progress of at least one of these diseases, amyotrophic lateral sclerosis, are beginning to show promising results. The first clinical trials in spinal muscular atrophy are currently underway. A number of other developments have raised the quality of clinical trials, which should improve their productivity and efficiency in the future.

Clinical Trials in Spinal Muscular Atrophy: Protocol Development and Reliability of Quantitative Strength Assessment Method

We have developed a protocol to evaluate, prospectively, patients with spinal muscular atrophy (SMA) so that the natural course may be defined and treatment efficacy measured. A fixed myometry system with a sensitivity of 0.5 kgs. of force was used to eliminate the subjectivity experienced with manual muscle testing and handheld dynamometry. Thirteen patients were evaluated weekly for twelve weeks by the clinical evaluators (CEs). Intrarater reliability was established by demonstrating that repeated measurements by the same examiner were consistent. The CEs examined patients at each of the participating institutions on three separate occasions. Interrater reliability was demonstrated by showing that the strength evaluations made on the same subject by different evaluators did not differ significantly. The fixed myometry system was found to be a highly reliable method for evaluating very weak muscle groups in patients with SMA.