small molecules

2025-01-02 | Transitioning From Nusinersen to Risdiplam for Spinal Muscular Atrophy in Clinical Practice: A Single-Center Experience.

Nusinersen and risdiplam are U.S. Food and Drug Administration (FDA)-approved treatments for spinal muscular atrophy (SMA). No head-to-head clinical trials to assess efficacy exist. Observational studies are needed to determine if transitioning to risdiplam is safe and efficacious. This retrospective study at Nationwide Children's Hospital included individuals with SMA treated with nusinersen who switched to risdiplam. Motor, pulmonary and bulbar function were assessed before and 2 years after nusinersen and risdiplam initiation. Forty-four individuals were included: 11 with SMA type 1, 25 with SMA type 2 and 8 with SMA type 3. Motor function improved after initiation of nusinersen treatment with the most significant improvements seen in the first year. After transition to risdiplam, motor function remained largely stable. Need for noninvasive ventilation (NIV) overnight occurred in both groups. Cough peak flow significantly improved in the risdiplam group. Hospitalizations were the same in both groups. One individual in the nusinersen group gained the ability to take some food by mouth; two individuals in the risdiplam group achieved some oral feeding and two became exclusively orally fed. As expected, motor function was most improved in treatment naïve individuals in the first year after nusinersen initiation. Over half of our study population had posterior spinal fusion surgery (57%) which significantly impacted motor and respiratory outcomes, though slightly less so in the risdiplam group. Overall, our data demonstrates that transitioning from nusinersen to risdiplam is associated with a favorable safety profile and stable motor outcomes.

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2024-11-21 | Risdiplam: therapeutic effects and tolerability in a small cohort of 6 adult type 2 and type 3 SMA patients.

Risdiplam is a validated treatment for adult SMA patients, but clear guidelines concerning functional assessment at baseline and during the follow-up are still limited, especially in terms of sensible and validated outcome measures able to capture minimal changes in motor performances induced by therapy. The aim of this work is to describe the effect of Risdiplam on a cohort of 6 adult type 2 and type 3 SMA patients, using Motor Function Measure (MFM32) as a standardized scaleto quantify the motor improvements induced by therapy. Risdiplam at the dose of 5 mg/daily was administered to a population of 6 (4 F;2 M) type 2 (N = 4) and type 3 (N = 2), adult SMA patients. Two patients were previously treated by Nusinersen, later suspended due to side effects. At baseline, all patients received a neuromuscular evaluation and a MFM32 assessment. After the beginning of treatment, we evaluated MFM32, patient reported outcomes (PROs), and adverse events over 7-27 months of follow-up. The MFM32 showed an increased score ranging from + 2.16% to + 7.29% in 4 patients. The improvement was maintained overtime, with two patients presenting the longest follow-up period of 24 and 27 months respectively. Subdomain D3 was ameliorated in 66.6% of patients. Two patients previously treated with Nusinersen maintained the pre-Risdiplam scores. The HFMSE was also performed and failed to show significant improvements after treatment. All patients reported subjective ameliorations. The commonest PROs were improvements in breath fatigue, voice's intelligibility, hand strength and dexterity. Adverse effects were mild and decreased over time. Risdiplam is a well-tolerated treatment in our cohort of adult type 2 and type 3 SMA patients and resulted in improvement or stabilization in motor functions. MFM32 proved to be sensitive to detect changes induced by therapy. Subjective meaningful improvements were sustained overtime especially in bulbar functions, breath fatigue and distal motor abilities.

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2024-06-21 | Real-world evidence: Risdiplam in a patient with spinal muscular atrophy type I with a novel splicing mutation and one SMN2 copy.

Spinal muscular atrophy (SMA), which results from the deletion or/and mutation in the SMN1 gene, is an autosomal recessive neuromuscular disorder that leads to weakness and muscle atrophy. SMN2 is a paralogous gene of SMN1. SMN2 copy number affects the severity of SMA, but its role in patients treated with disease modifying therapies is unclear. The most appropriate individualized treatment for SMA has not yet been determined. Here, we reported a case of SMA type I with normal breathing and swallowing function. We genetically confirmed that this patient had a compound heterozygous variant: one deleted SMN1 allele and a novel splice mutation c.628-3T>G in the retained allele, with one SMN2 copy. Patient-derived sequencing of 4 SMN1 cDNA clones showed that this intronic single transversion mutation results in an alternative exon (e)5 3' splice site, which leads to an additional 2 nucleotides (AG) at the 5' end of e5, thereby explaining why the patient with only one copy of SMN2 had a mild clinical phenotype. Additionally, a minigene assay of wild type and mutant SMN1 in HEK293T cells also demonstrated that this transversion mutation induced e5 skipping. Considering treatment cost and goals of avoiding pain caused by injections and starting treatment as early as possible, risdiplam was prescribed for this patient. However, the patient showed remarkable clinical improvements after treatment with risdiplam for 7 months despite carrying only one copy of SMN2. This study is the first report on the treatment of risdiplam in a patient with one SMN2 copy in a real-world setting. These findings expand the mutation spectrum of SMA and provide accurate genetic counseling information, as well as clarify the molecular mechanism of careful genotype-phenotype correlation of the patient.

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2024-05-11 | JEWELFISH: 24-month results from an open-label study in non-treatment-naïve patients with SMA receiving treatment with risdiplam.

Risdiplam is a once-daily oral, survival of motor neuron 2 (SMN2) splicing modifier approved for the treatment of spinal muscular atrophy (SMA). JEWELFISH (NCT03032172) investigated the safety, tolerability, pharmacokinetics (PK), and PK/pharmacodynamic (PD) relationship of risdiplam in non-treatment-naïve patients with SMA. JEWELFISH enrolled adult and pediatric patients (N = 174) with confirmed diagnosis of 5q-autosomal recessive SMA who had previously received treatment with nusinersen (n = 76), onasemnogene abeparvovec (n = 14), olesoxime (n = 71), or were enrolled in the MOONFISH study (NCT02240355) of the splicing modifier RG7800 (n = 13). JEWELFISH was an open-label study with all participants scheduled to receive risdiplam. The most common adverse event (AE) was pyrexia (42 patients, 24%) and the most common serious AE (SAE) was pneumonia (5 patients, 3%). The rate of AEs and SAEs decreased by > 50% from the first to the second year of treatment, and there were no treatment-related AEs that led to withdrawal from treatment. An increase in SMN protein in blood was observed following risdiplam treatment and sustained over 24 months of treatment irrespective of previous treatment. Exploratory efficacy assessments of motor function showed an overall stabilization in mean total scores as assessed by the 32-item Motor Function Measure, Hammersmith Functional Motor Scale-Expanded, and Revised Upper Limb Module. The safety profile of risdiplam in JEWELFISH was consistent with previous clinical trials of risdiplam in treatment-naïve patients. Exploratory efficacy outcomes are reported but it should be noted that the main aim of JEWELFISH was to assess safety and PK/PD, and the study was not designed for efficacy analysis. TRIAL REGISTRATION: The study was registered (NCT03032172) on ClinicalTrials.gov on January 24, 2017; First patient enrolled: March 3, 2017.

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2024-03-12 | Risdiplam in Spinal Muscular Atrophy: Safety Profile and Use Through The Early Access to Medicine Scheme for the Paediatric Cohort in Great Britain.

Spinal muscular atrophy (SMA) is a progressive neuromuscular disease caused by mutations in Survival motor neuron 1 (SMN1) gene, leading to reduction in survival motor neuron protein (SMN), key for motor neuron survival and function in the brainstem and spinal cord. Risdiplam is an orally administered SMN2-splicing modifier which increases production of functional SMN protein. Risdiplam was offered in the UK under early access to medicines scheme (EAMS) to SMA type 1 and 2 patients aged 2 months and older, not suitable for authorised treatments from September 2020 to December 2021. To describe the largest paediatric European real-world set of data on patients' characteristics and short-term safety for risdiplam in Great Britain through EAMS. We collated data from SMA REACH UK a national clinical and research network for all patients enrolled onto EAMS and assessed all submitted adverse events. Of the 92 patients; 78% were Type 2 SMA, mean age 10.9 years, range 0-17 years. 56 were treatment naïve, 33 previously treated; of these 25 had received nusinersen, 3 previous treatment unknown. Sixty adverse events (AEs) were reported occurring in 34 patients. The commonest were respiratory tract infections and gastrointestinal disturbance. Four life-threatening events were reported with 2 deaths and permanent cessation of risdiplam in 3 patients.Overall, 38/60 AEs were considered unrelated to risdiplam, 10/60 related to risdiplam and for 12/60 causality not specified. This study found a safety profile similar to clinical trials with no new safety concerns identified. With the restricted eligibility of onasemnogene abeparvovec and complications of nusinersen administration, EAMS allowed access or continued treatment to naïve patients or patients no longer suitable for approved medications. Collection of longitudinal data for this complex population is needed, to provide greater insights into risdiplam's role in addressing patients' needs into the future.

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oligonucleotides

2025-01-21 | Difficulty of administration of nusinersen in complex-column spinal muscular atrophy: New alternative technique by means of cervical intrathecal access through an Ommaya reservoir.

The study aimed to describe a new Ommaya reservoir implantation method in late-onset SMA patients, assessing its safety and effectiveness under standard clinical conditions. Prospective observational study. Lumbar intrathecal access was unfeasible due to significant scoliosis and prior spinal surgeries with instrumentation. Patients were infused with Nusinersen through the Ommaya reservoir at Hospital Universitario La Paz (Spain) following the standard dosing protocol. The cohort was composed of 6 patients, 5 individuals with type 2 SMA (83.3 %), and 1 patient presenting with type 3 SMA. 4 of the patients were functionally sitters (66.7 %) and 2 had lost this ability prior to initiating treatment (non-sitters). Mean treatment was 34.7 months. Patient discharge was done in all the cases within 48 h post-admission; no significant postoperative complications or during administration of nusinersen were reported. Functional progress was observed in all patients. Hammersmith Functional Motor Scale Expanded (HFMSE) showed a low average increase (1.0), attributed to the severity of baseline functional impairments. Improvements in upper extremity motor function, measured by the Revised Upper Limb Module (RULM), were more pronounced, with an average improvement of 3.3. Disability levels as measured by the Egen Klassifikation 2 (EK2) scale, declined by 4.4. the current study broadens knowledge regarding the efficacy and safety of using an Ommaya reservoir to administer nusinersen in patients with SMA Types 2 and 3. The technique demonstrated rapid, straightforward drug delivery through a subcutaneous needle, maintaining optimal sterility without radiation or the need for a multidisciplinary team.

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2025-01-21 | Effect of nusinersen on pulmonary function in children with spinal muscular atrophy in the plateau region: A pilot study.

The drug nusinersen is applied to improve motor function in patients with spinal muscle atrophy (SMA). However, research on the effects of this treatment on lung function is lacking. To investigate the effect of nusinersen on lung function in children with SMA in the Plateau. A total of 20 patients with SMA (types 1, 2, or 3) who started nusinersen treatment at the Department of Pediatrics at Yunnan First People's Hospital from March 2022 and February 2024 were studied. A retrospective study was conducted to investigate changes in lung function parameters (including forced vital capacity, forced expiratory volume at 1 s, forced expiratory volume at 1 s/forced vital capacity, and peak expiratory flow) in patients with SMA treated with nusinersen. 20 patients (13 male, 7 female; aged 5-16 years) were enrolled, including 2, 9, and 9 with SMA types 1, 2, and 3, respectively. The mean value of FVC % and FEV1/FVC % did not decrease further following nusinersen treatment in any patients. The mean value of FEV1% was 4.4 % and 5.0 % higher than before treatment in all patients (P = 0.03), and those with type 2 SMA (P = 0.04), respectively. The overall mean PEF % did not decrease any further after treatment. However, the average level in the type 2 group increased by 2.9 % (P = 0.03). Patients with SMA, particularly those classified as type 2, showed a trend of improvement in lung function following nusinersen treatment.

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2025-01-05 | Successful pregnancy of an SMA type 3 sitter on Nusinersen therapy - a case report.

Due to improved treatment options, more SMA patients reach childbearing age. Currently, limited data on pregnant SMA patients is available, especially in relation to disease-modifying therapies (DMT). This case report helps to elucidate new approaches for future guidelines in the management of pregnancy and SMA. A 33-year-old wheelchair-bound patient with SMA type 3 (sitter) became pregnant following 36 months of Nusinersen treatment. The last dose was administered in the third gestational week. After pregnancy was confirmed, therapy was stopped immediately. A healthy child was born in the 34th gestational week by caesarean section. After a short nursing period, Nusinersen was restarted 6 weeks after the expected gestational date. At this time, the patient reported deteriorated motor functions, which stabilized at a lower level compared to pre-pregnancy in the 2-year follow-up, despite restarting Nusinersen treatment. So far, only few cases of successful pregnancies of SMA patients on DMT have been reported. In natural history, the majority of patients experienced an increased deterioration of motor function while fetal outcome was not impaired. Our case shows that although Nusinersen treatment was applied in the third gestational week prior to proof of pregnancy, outcome was positive for mother and child. Future studies will have to determine whether ongoing treatment with Nusinersen during pregnancy should be recommended.

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2024-12-16 | Efficacy and safety of Nusinersen among children with spinal muscular atrophy from North India: A prospective cohort study (NICE-SMA study).

Intra-thecal Nusinersen has been approved for the treatment of Spinal muscular atrophy (SMA). Limited data is available regarding the efficacy and safety of Nusinersen in children with SMA type 2 and 3 from North India. To study the efficacy and safety of Nusinersen among children with SMA type 2 and 3 from North India compared to standard of care (SOC) over 12 months. Children with a genetically confirmed diagnosis of SMA and ≥2 copies of the SMN2 gene were screened for enrolment in prospective study design. Revised Hammersmith score (RHS) and revised upper limb module (RULM) were assessed every three months. Compound muscle action potentials (CMAPs) at median and ulnar nerves and quality of life (QOL) were performed at baseline and 12 months. Intra-thecal procedure-related and treatment-emergent side effects in children receiving Nusinersen therapy were recorded. Outcome measures at 6 and 12 months were compared between the Nusinersen and SOC groups. Forty-two children with SMA, mean age of 85 ± 6 months, including 16 in the Nusinersen group and 26 in the SOC group, were enrolled. The mean RHS score in the Nusinersen group increased from the baseline of 35 ± 18 to 38.9 ± 19, and 39.9 ± 17 at 6 and 12 months (p value-0.001), in the SOC group increased from the baseline of 28.8 ± 15, to 29.6 ± 16, and 29.9 ± 17 at 6 and 12 months respectively (p value-0.35). The mean gain in the RHS score over 12 months in the Nusinersen group was significantly higher compared to the SOC group (p-value 0.02). RULM showed significant gain in the Nusinersen group compared to the SOC group over 12 months (p value 0.03). The median and ulnar nerve CMAPs, and QOL were similar in both the groups. A total of 119 intrathecal injections of Nusinersen were given. Most adverse events were mild and related to the intra-thecal procedure. Intra-thecal Nusinersen therapy among children with late-onset SMA from North India over 12-month duration was associated with improvement in motor abilities as measured by RHS compared to SOC. Intra-thecal Nusinersen was safe and tolerated well.

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2024-11-25 | Efficacy of Nusinersen Treatment in Type 1, 2, and 3 Spinal Muscular Atrophy: Real-World Data from a Single-Center Study.

Spinal muscular atrophy (SMA) is an inherited neuromuscular disease characterized by progressive muscle weakness and atrophy due to the absence of the survival motor neuron 1 (SMN1) gene. SMA is classified into types 0 through 4 based on the age of symptom onset and the severity of motor function decline. Recent advances in SMA treatment, including nusinersen, onasemnogene abeparvovec, and risdiplam, have significantly improved the prognosis of SMA patients. This study evaluated the safety and efficacy of nusinersen in pediatric patients with SMA types 1, 2, and 3 in a real-world clinical setting. This prospective observational single-center study assessed the treatment effects of nusinersen in 23 pediatric patients with genetically confirmed SMA over a 22-month observation period. All the participants received intrathecal loading doses of 12 mg of nusinersen on days 1, 14, 28, and 63, followed by maintenance doses every four months. Functional assessments were conducted using the CHOP-INTEND scale. Data were collected during routine patient visits, including clinical laboratory tests and vital sign parameters, and adverse events were recorded. The inclusion criteria were defined by the national reimbursement program for nusinersen treatment in Poland. Initially, 37 patients ranging from 1 month old to 18 years old were included, but 23 were ultimately observed due to changes in treatment regimens or assessment scales. The patients showed significantly improved CHOP-INTEND scores over the 22-month period. At 6 months, the average increase was 4.2 points, continuing to 17.8 points at 22 months. By the end of the study, 100% of patients showed either stabilization or improvement, with significant clinical improvements observed in several patients. Nusinersen was generally well-tolerated, with post-lumbar puncture headache and lower back pain being the most common adverse events. Nusinersen treatment significantly enhances motor function in pediatric patients with SMA types 1, 2, and 3. This study demonstrates the importance of early and sustained treatment, with most patients showing the continuous improvement or stabilization of motor function. These findings support the use of nusinersen as an effective therapy for SMA; however, further research is needed to understand the long-term outcomes and optimize treatment strategies.

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gene therapies

2025-01-13 | Safety and Efficacy of IV Onasemnogene Abeparvovec for Pediatric Patients With Spinal Muscular Atrophy: The Phase 3b SMART Study.

Safety and efficacy of IV onasemnogene abeparvovec has been demonstrated for patients with spinal muscular atrophy (SMA) weighing <8.5 kg. SMART was the first clinical trial to evaluate onasemnogene abeparvovec for participants weighing 8.5-21 kg. SMART was an open-label, multicenter, phase 3b study conducted across 13 sites in 9 countries (NCT04851873). Symptomatic pediatric participants with SMA (any type; treatment-naïve or had discontinued prior treatment) were stratified into 3 weight cohorts (≥8.5-13, >13-17, and >17-21 kg), administered onasemnogene abeparvovec, and followed for 52 weeks. Corticosteroids were initiated 24 hours before infusion with dose increases in response to adverse events (AEs) and subsequent tapering at investigator discretion. The primary objective was safety. Secondary objective was efficacy (motor function/motor milestones). Twenty-four participants were enrolled; the majority had SMA type 2 (n = 11), 3 SMN2 copies (n = 18), and prior treatment (n = 21). All participants completed the study; no deaths occurred. All participants had ≥1 treatment-related AE(s), 7 of 24 (29%) had serious treatment-related AEs, and 23 of 24 (96%) had ≥1 AE of special interest. Twenty of 24 participants (83%) had asymptomatic hepatotoxicity events, which were primarily transaminase elevations. No participant had bilirubin elevations >2× upper limit of normal, developed symptomatic hepatotoxicity, or met Hy law criteria. Transient asymptomatic thrombocytopenia events were reported in 17 of 24 participants (71%); all resolved spontaneously with no related bleeding events reported. Three of 24 participants (13%) had cardiac AEs (all unrelated to treatment). No thrombotic microangiopathy or dorsal root ganglionopathy-related AEs were reported. AE frequency and severity were similar across weight groups, although corticosteroid exposure was greater for the 2 heavier cohorts (median 135.0, 201.0, and 194.0 days, respectively) with 37% and 33% still on corticosteroids at the study end. By week 52, most participants maintained or improved motor function (Hammersmith Functional Motor Scale-Expanded 16/18; Revised Upper Limb Module 15/17); 4 participants (all 3 SMN2 copies) achieved new motor milestones. Onasemnogene abeparvovec safety profile was similar across weight groups in this heterogenous participant population. Frequency and duration of asymptomatic aminotransferase elevations and thrombocytopenia are notable findings. Most participants demonstrated maintenance or improvement of motor function, suggesting clinical benefit for patients with SMA weighing up to 21 kg. ClinicalTrials.gov identifier (NCT04851873, clinicaltrials.gov/study/NCT04851873) submitted April 19, 2021. First participant enrolled on September 8, 2021. This study provides Class IV evidence that intravenous onasemnogene abeparvovec is safe in pediatric patients with SMA who weigh 8.5-21 kg.

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2024-12-18 | Onasemnogene Abeparvovec is Safe in Hemolytic Disease of the Newborn: A Case Report.

Spinal muscular atrophy (SMA) is a rare autosomal recessive genetic disease caused by Survival Motor Protein 1 (SMN1) gene mutations. Classically divided into three types, SMA is characterized by hypotonia, weakness, and tongue fasciculation in the first 6 months of life in type 1, inability to walk and limb weakness in type 2, and failure to run with proximal weakness in type 3 SMA. With the advent of newborn screening, treating presymptomatic patients with Onasemnogene abeparvovec (OA) is the treatment of choice in some centers worldwide. The incidence of jaundice is high in this age group, with no recommendation to guide the use of OA in newborns with jaundice. To our knowledge, treating an SMA patient with alloimmune hemolytic disease of the newborn (HDN), a relatively common disease in the newborn period, has never been reported in the past. We report our experience with dosing a presymptomatic child with SMA who had neonatal jaundice and hemolytic anemia due to hemolytic disease of the newborn who tolerated the treatment well. To our knowledge, this is the first case to report the safety of this novel treatment for an SMA patient with alloimmune HDN.

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2024-12-03 | Respiratory outcomes of onasemnogene abeparvovec treatment for spinal muscular atrophy: national real-world cohort study.

Onasemnogene abeparvovec (OA) is a novel gene replacement therapy for patients with spinal muscular atrophy (SMA). This study provides real-world respiratory data for pediatric SMA patients receiving OA who were assessed before and one year after treatment in a multicenter cohort study conducted from 2019 to 2021. Twenty-five OA-treated SMA patients (23 with type 1 and 2 with type 2; median age at treatment 6.1 months, with a range of 0.36-23 months) were included. Sixteen were treatment-naïve, and nine had received various prior treatments. Two patients died due to respiratory failure during the study period. Of the remaining 23 patients, four were put on non-invasive ventilation (NIV), bringing ventilated patients to a total of ten during the post-treatment year. Three patients required permanent NIV support, while 13 did not require any respiratory support. Ventilation time decreased from 14.3 to 11.1 hours per day, and respiratory hospitalizations decreased by 26% (from 0.76 to 0.57 per life year). Fifteen of the 23 patients maintained full oral nutrition at study closure compared to 20 of the 25 at study initiation. This real-world data analysis demonstrates that OA may improve respiratory outcomes in SMA patients. Importantly, compounding factors, such as age at treatment initiation, treatment combinations, and natural history, may influence the respiratory course, thus highlighting the need for standardized long-term management. What is Known: • Respiratory failure is a leading cause of mortality in untreated spinal muscular atrophy type 1 patients. • Onasemnogene abeparvovec (OA) improves neurological outcomes, but real-world respiratory data are limited. What is New: • Our real-world analysis suggests OA may improve respiratory outcomes. • Age at treatment and treatment combinations may also influence respiratory trajectory.

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2024-09-28 | Onasemnogene Abeparvovec Gene Therapy and Risdiplam for the Treatment of Spinal Muscular Atrophy in Thailand: A Cost-Utility Analysis.

Caring for individuals with spinal muscular atrophy (SMA), a rare genetic disorder, poses tremendous challenges for the economy and healthcare system. This study evaluated the cost-utility of onasemnogene abeparvovec-xioi gene therapy and risdiplam for SMA in Thailand. A Markov model was used to analyze the lifetime costs and outcomes of these treatments compared with standard of care for symptomatic SMA types 1 and 2-3. SMA type 1 patients were treated with one of either onasemnogene or risdiplam, while SMA types 2-3 patients received risdiplam. Data on disease progression and medical costs were sourced from hospital databases, while treatment efficacy was based on clinical trials. Interviews with patients and caregivers provided data on non-medical costs and utilities. Base case cost-effectiveness and sensitivity analyses were conducted, with the incremental cost-effectiveness ratio (ICER) calculated in US dollars (USD) per quality-adjusted life year (QALY) gained, against a willingness-to-pay threshold of 4444 USD/QALY gained. For SMA type 1, the ICERs for onasemnogene and risdiplam were 163,102 and 158,357 USD/QALY gained, respectively. For SMA types 2-3, the ICER for risdiplam was 496,704 USD/QALY gained. While onasemnogene and risdiplam exceeded the value-for-money threshold of the Thai healthcare system, they yielded the highest QALY gains among all approved medications. Policy-makers should incorporate various pieces of evidence alongside the cost-effectiveness results for rare diseases with costly drugs. Additionally, cost-effectiveness findings are useful for price negotiations and alternative financial funding, which allows policy-makers to seek solutions to ensure patient access, aligning with universal health coverage principles in Thailand.

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2024-08-26 | Timing of SMN replacement therapies in mouse models of spinal muscular atrophy: a systematic review and meta-analysis.

Mutations in the Survival of Motor Neuron 1 gene lead to a loss of survival motor neuron protein in patients with spinal muscular atrophy. Revolutionary advances in gene therapy have led to survival motor neuron-replacement therapies that significantly prolong life expectancy and improve neuromuscular function. However, accumulating evidence suggests that the timing of survival motor neuron-replacement therapies is a critical determinant of success. We performed a systematic review and meta-analysis of all pre-clinical studies testing survival motor neuron replacement therapies in mouse models of spinal muscular atrophy to assess the impact of timing of delivery on therapeutic effectiveness. We incorporated four databases in this pre-registered study (PROSPERO 2020 CRD42020200180): EMBASE, PubMed, Scopus and Web of Science. Inclusion criteria were; primary research article, a measure of survival analysis, use of survival motor neuron mouse model and evaluation of survival motor neuron-targeting therapy. Exclusion criteria included; use of therapies not known to directly target survival motor neuron, genetic manipulations and/or lack of appropriate controls. We screened papers using the SyRF platform. The main outcome we assessed was survival in treated groups compared to untreated groups. We performed meta-analysis of survival using median survival ratio and the random effects model and measured heterogeneity using the I 2 statistic. Subgroup analyses were performed to assess treatment efficacy based on timing of intervention (embryonic delivery, day of birth, postnatal day 2 and postnatal day 3 or later) and treatment type. If detailed in the studies, body weight compared to untreated spinal muscular atrophy models and motor neuron number were included as secondary outcomes for meta-analysis. 3469 studies were initially identified, with 78 ultimately included. Survival motor neuron-replacement therapies significantly affected survival in favour of treatment by a factor of 1.20 (95% CI 1.10-1.30, P < 0.001) with high heterogeneity (I 2 = 95%). Timing of treatment was a significant source of heterogeneity (P < 0.01), with earlier treatment having a greater impact on survival. When stratified by type of treatment, earlier treatment continued to have the strongest effect with viral vector replacement therapy and antisense oligonucleotide therapy. Secondary outcome measures of body weight and spinal motor neuron counts were also positively associated with early treatment. Earlier delivery of survival motor neuron replacement therapies is therefore a key determinant of treatment efficacy in spinal muscular atrophy.

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antibodies

2024-10-16 | Taldefgrobep Alfa and the Phase 3 RESILIENT Trial in Spinal Muscular Atrophy.

Spinal muscular atrophy (SMA) is a rare, genetic neurodegenerative disorder caused by insufficient production of survival motor neuron (SMN) protein. Diminished SMN protein levels lead to motor neuron loss, causing muscle atrophy and weakness that impairs daily functioning and reduces quality of life. SMN upregulators offer clinical improvements and increased survival in SMA patients, although significant unmet needs remain. Myostatin, a TGF-β superfamily signaling molecule that binds to the activin II receptor, negatively regulates muscle growth; myostatin inhibition is a promising therapeutic strategy for enhancing muscle. Combining myostatin inhibition with SMN upregulation, a comprehensive therapeutic strategy targeting the whole motor unit, offers promise in SMA. Taldefgrobep alfa is a novel, fully human recombinant protein that selectively binds to myostatin and competitively inhibits other ligands that signal through the activin II receptor. Given a robust scientific and clinical rationale and the favorable safety profile of taldefgrobep in patients with neuromuscular disease, the RESILIENT phase 3, randomized, placebo-controlled trial is investigating taldefgrobep as an adjunct to SMN upregulators in SMA (NCT05337553). This manuscript reviews the role of myostatin in muscle, explores the preclinical and clinical development of taldefgrobep and introduces the phase 3 RESILIENT trial of taldefgrobep in SMA.

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2024-08-06 | Long-term efficacy, safety, and patient-reported outcomes of apitegromab in patients with spinal muscular atrophy: results from the 36-month TOPAZ study.

At 12 months in the phase 2 TOPAZ study, treatment with apitegromab was associated with both an improved motor function in patients with Type 2 or 3 spinal muscular atrophy (SMA) and with a favorable safety profile. This manuscript reports the extended efficacy and safety in the nonambulatory group of the TOPAZ study at 36 months. Patients who completed the primary study (NCT03921528) could enroll in an open-label extension, during which patients received apitegromab 20 mg/kg by intravenous infusion every 4 weeks. Patients were assessed periodically via the Hammersmith Functional Motor Scale-Expanded (HFMSE), Revised Upper Limb Module (RULM), World Health Organization (WHO) motor development milestones, Pediatric Evaluation of Disability Inventory Computer Adaptive Test (PEDI-CAT) Daily Activities and Mobility domains, and Patient-Reported Outcomes Measurement Information System (PROMIS) Fatigue questionnaire. Of the 58 patients enrolled in TOPAZ, 35 were nonambulatory (mean age 7.3 years). The mean change at 36 months in HFMSE score from baseline was +4.0 (standard deviation [SD]: 7.54), and + 2.4 (3.24) for RULM score (excluding n = 7 after scoliosis surgery). Caregiver-reported outcomes (PEDI-CAT and PROMIS Fatigue) showed improvements from baseline over 36 months. In addition, most patients (28/32) improved or maintained WHO motor milestones achieved at baseline. The most frequently reported treatment-emergent adverse events were pyrexia (48.6%), nasopharyngitis (45.7%), COVID-19 infection (40.0%), vomiting (40.0%), and upper respiratory tract infection (31.4%). The benefit of apitegromab treatment observed at 12 months was sustained at 36 months with no new safety findings.

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2024-02-14 | Safety and Efficacy of Apitegromab in Patients With Spinal Muscular Atrophy Types 2 and 3: The Phase 2 TOPAZ Study.

Currently approved therapies for spinal muscular atrophy (SMA) reverse the degenerative course, leading to better functional outcome, but they do not address the impairment arising from preexisting neurodegeneration. Apitegromab, an investigational, fully human monoclonal antibody, inhibits activation of myostatin (a negative regulator of skeletal muscle growth), thereby preserving muscle mass. The phase 2 TOPAZ trial assessed the safety and efficacy of apitegromab in individuals with later-onset type 2 and type 3 SMA. In this study, designed to investigate potential meaningful combinations of eligibility and treatment regimen for future studies, participants aged 2-21 years received IV apitegromab infusions every 4 weeks for 12 months in 1 of 3 cohorts. Cohort 1 stratified ambulatory participants aged 5-21 years into 2 arms (apitegromab 20 mg/kg alone or in combination with nusinersen); cohort 2 evaluated apitegromab 20 mg/kg combined with nusinersen in nonambulatory participants aged 5-21 years; and cohort 3 blindly evaluated 2 randomized apitegromab doses (2 and 20 mg/kg) combined with nusinersen in younger participants ≥2 years of age. The primary efficacy measure was mean change from baseline using the Hammersmith Functional Motor Scale version appropriate for each cohort. Data were analyzed using a paired t test with 2-sided 5% type 1 error for the mean change from baseline for predefined cohort-specific primary efficacy end points. Fifty-eight participants (mean age 9.4 years) were enrolled at 16 trial sites in the United States and Europe. Participants had been treated with nusinersen for a mean of 25.9 months before enrollment in any of the 3 trial cohorts. At month 12, the mean change from baseline in Hammersmith scale score was -0.3 points (95% CI -2.1 to 1.4) in cohort 1 (n = 23), 0.6 points (-1.4 to 2.7) in cohort 2 (n = 15), and in cohort 3 (n = 20), the mean scores were 5.3 (-1.5 to 12.2) and 7.1 (1.8 to 12.5) for the 2-mg/kg (n = 8) and 20-mg/kg (n = 9) arms, respectively. The 5 most frequently reported treatment-emergent adverse events were headache (24.1%), pyrexia (22.4%), upper respiratory tract infection (22.4%), cough (22.4%), and nasopharyngitis (20.7%). No deaths or serious adverse reactions were reported. Apitegromab led to improved motor function in participants with later-onset types 2 and 3 SMA. These results support a randomized, placebo-controlled phase 3 trial of apitegromab in participants with SMA. This trial is registered with ClinicalTrials.gov (NCT03921528). This study provides Class III evidence that apitegromab improves motor function in later-onset types 2 and 3 spinal muscular atrophy.

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2022-11-08 | Advances and limitations for the treatment of spinal muscular atrophy.

Spinal muscular atrophy (5q-SMA; SMA), a genetic neuromuscular condition affecting spinal motor neurons, is caused by defects in both copies of the SMN1 gene that produces survival motor neuron (SMN) protein. The highly homologous SMN2 gene primarily expresses a rapidly degraded isoform of SMN protein that causes anterior horn cell degeneration, progressive motor neuron loss, skeletal muscle atrophy and weakness. Severe cases result in limited mobility and ventilatory insufficiency. Untreated SMA is the leading genetic cause of death in young children. Recently, three therapeutics that increase SMN protein levels in patients with SMA have provided incremental improvements in motor function and developmental milestones and prevented the worsening of SMA symptoms. While the therapeutic approaches with Spinraza®, Zolgensma®, and Evrysdi® have a clinically significant impact, they are not curative. For many patients, there remains a significant disease burden. A potential combination therapy under development for SMA targets myostatin, a negative regulator of muscle mass and strength. Myostatin inhibition in animal models increases muscle mass and function. Apitegromab is an investigational, fully human, monoclonal antibody that specifically binds to proforms of myostatin, promyostatin and latent myostatin, thereby inhibiting myostatin activation. A recently completed phase 2 trial demonstrated the potential clinical benefit of apitegromab by improving or stabilizing motor function in patients with Type 2 and Type 3 SMA and providing positive proof-of-concept for myostatin inhibition as a target for managing SMA. The primary goal of this manuscript is to orient physicians to the evolving landscape of SMA treatment.

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2021-06-22 | A Randomized Phase 1 Safety, Pharmacokinetic and Pharmacodynamic Study of the Novel Myostatin Inhibitor Apitegromab (SRK-015): A Potential Treatment for Spinal Muscular Atrophy.

Apitegromab (SRK-015) is an anti-promyostatin monoclonal antibody under development to improve motor function in patients with spinal muscular atrophy, a rare neuromuscular disease. This phase 1 double-blind, placebo-controlled study assessed safety, pharmacokinetic parameters, pharmacodynamics (serum latent myostatin), and immunogenicity of single and multiple ascending doses of apitegromab in healthy adult subjects. Subjects were administered single intravenous ascending doses of apitegromab of 1, 3, 10, 20, 30 mg/kg or placebo, and multiple intravenous ascending doses of apitegromab of 10, 20, 30 mg/kg or placebo. Following single ascending doses, the pharmacokinetic parameters of apitegromab appeared to be similar across all dose groups, following a biphasic pattern of decline in the concentration-time curve. The mean apparent terminal t1/2 after single intravenous doses of apitegromab ranged from 24 to 31 days across dose groups. Dose-related increases were observed in Cmax following multiple ascending doses. Single and multiple apitegromab doses resulted in dose-dependent and sustained increases in serum latent myostatin, indicating robust target engagement. Apitegromab was safe and well tolerated, on the basis of the adverse event (AE) profile with no clinically meaningful changes in baseline vital signs, electrocardiograms, or clinical laboratory parameters and no anti-drug antibody formation. These results support continued investigation of apitegromab for the treatment of patients with milder forms (type 2 and 3) of spinal muscular atrophy.

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2024-04-02 | Administration of adipose-derived stem cells extracellular vesicles in a murine model of spinal muscular atrophy: effects of a new potential therapeutic strategy.

Spinal Muscular Atrophy (SMA) is an autosomal-recessive neuromuscular disease affecting children. It is caused by the mutation or deletion of the survival motor neuron 1 (SMN1) gene resulting in lower motor neuron (MN) degeneration followed by motor impairment, progressive skeletal muscle paralysis and respiratory failure. In addition to the already existing therapies, a possible combinatorial strategy could be represented by the use of adipose-derived mesenchymal stem cells (ASCs) that can be obtained easily and in large amounts from adipose tissue. Their efficacy seems to be correlated to their paracrine activity and the production of soluble factors released through extracellular vesicles (EVs). EVs are important mediators of intercellular communication with a diameter between 30 and 100 nm. Their use in other neurodegenerative disorders showed a neuroprotective effect thanks to the release of their content, especially proteins, miRNAs and mRNAs. In this study, we evaluated the effect of EVs isolated from ASCs (ASC-EVs) in the SMNΔ7 mice, a severe SMA model. With this purpose, we performed two administrations of ASC-EVs (0.5 µg) in SMA pups via intracerebroventricular injections at post-natal day 3 (P3) and P6. We then assessed the treatment efficacy by behavioural test from P2 to P10 and histological analyses at P10. The results showed positive effects of ASC-EVs on the disease progression, with improved motor performance and a significant delay in spinal MN degeneration of treated animals. ASC-EVs could also reduce the apoptotic activation (cleaved Caspase-3) and modulate the neuroinflammation with an observed decreased glial activation in lumbar spinal cord, while at peripheral level ASC-EVs could only partially limit the muscular atrophy and fiber denervation. Our results could encourage the use of ASC-EVs as a therapeutic combinatorial treatment for SMA, bypassing the controversial use of stem cells.

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2021-11-10 | LCM-seq reveals unique transcriptional adaptation mechanisms of resistant neurons and identifies protective pathways in spinal muscular atrophy.

Somatic motor neurons are selectively vulnerable in spinal muscular atrophy (SMA), which is caused by a deficiency of the ubiquitously expressed survival of motor neuron protein. However, some motor neuron groups, including oculomotor and trochlear (ocular), which innervate eye muscles, are for unknown reasons spared. To reveal mechanisms of vulnerability and resistance in SMA, we investigate the transcriptional dynamics in discrete neuronal populations using laser capture microdissection coupled with RNA sequencing (LCM-seq). Using gene correlation network analysis, we reveal a TRP53-mediated stress response that is intrinsic to all somatic motor neurons independent of their vulnerability, but absent in relatively resistant red nucleus and visceral motor neurons. However, the temporal and spatial expression analysis across neuron types shows that the majority of SMA-induced modulations are cell type-specific. Using Gene Ontology and protein network analyses, we show that ocular motor neurons present unique disease-adaptation mechanisms that could explain their resilience. Specifically, ocular motor neurons up-regulate (1) Syt1, Syt5, and Cplx2, which modulate neurotransmitter release; (2) the neuronal survival factors Gdf15, Chl1, and Lif; (3) Aldh4, that protects cells from oxidative stress; and (4) the caspase inhibitor Pak4. Finally, we show that GDF15 can rescue vulnerable human spinal motor neurons from degeneration. This confirms that adaptation mechanisms identified in resilient neurons can be used to reduce susceptibility of vulnerable neurons. In conclusion, this in-depth longitudinal transcriptomics analysis in SMA reveals novel cell type-specific changes that, alone and combined, present compelling targets, including Gdf15, for future gene therapy studies aimed toward preserving vulnerable motor neurons.

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2021-07-09 | Plastin 3 in health and disease: a matter of balance.

For a long time, PLS3 (plastin 3, also known as T-plastin or fimbrin) has been considered a rather inconspicuous protein, involved in F-actin-binding and -bundling. However, in recent years, a plethora of discoveries have turned PLS3 into a highly interesting protein involved in many cellular processes, signaling pathways, and diseases. PLS3 is localized on the X-chromosome, but shows sex-specific, inter-individual and tissue-specific expression variability pointing towards skewed X-inactivation. PLS3 is expressed in all solid tissues but usually not in hematopoietic cells. When escaping X-inactivation, PLS3 triggers a plethora of different types of cancers. Elevated PLS3 levels are considered a prognostic biomarker for cancer and refractory response to therapies. When it is knocked out or mutated in humans and mice, it causes osteoporosis with bone fractures; it is the only protein involved in actin dynamics responsible for osteoporosis. Instead, when PLS3 is upregulated, it acts as a highly protective SMN-independent modifier in spinal muscular atrophy (SMA). Here, it seems to counteract reduced F-actin levels by restoring impaired endocytosis and disturbed calcium homeostasis caused by reduced SMN levels. In contrast, an upregulation of PLS3 on wild-type level might cause osteoarthritis. This emphasizes that the amount of PLS3 in our cells must be precisely balanced; both too much and too little can be detrimental. Actin-dynamics, regulated by PLS3 among others, are crucial in a lot of cellular processes including endocytosis, cell migration, axonal growth, neurotransmission, translation, and others. Also, PLS3 levels influence the infection with different bacteria, mycosis, and other pathogens.

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2019-03-14 | Prenatal transplantation of human amniotic fluid stem cells for spinal muscular atrophy.

To review the current medical and stem-cell therapy for spinal muscular atrophy (SMA) and prenatal transplantation of amniotic fluid stem cells in the future. SMA is an autosomal recessive inheritance of neurodegenerative disease, which is caused of the mutation in survival motor neuron. The severe-type SMA patients usually die from the respiratory failure within 2 years after birth. Recently, researchers had found that 3-methyladenine could inhibit the autophagy and had the capacity to reduce death of the neurons. The first food and drug administration-approved drug to treat SMA, Nusinersen, is a modified antisense oligonucleotide to target intronic splicing silencer N1 just recently launched. Not only medical therapy, but also stem cells including neural stem cells, embryonic stem cells, mesenchymal stem cells, and induced pluripotent stem cells could show the potential to repair the injured tissue and differentiate into neuron cells to rescue the SMA animal models. Human amniotic fluid stem cells (HAFSCs) share the potential of mesenchymal stem cells and could differentiate into tri-lineage-relative cells, which are also having the ability to restore the injured neuro-muscular function. In this review, we further demonstrate the therapeutic effect of using HAFSCs to treat type III SMA prenatally. HAFSCs, similar to other stem cells, could also help the improvement of SMA with even longer survival. The concept of prenatal stem-cell therapy preserves the time window to treat disease in utero with much less cell number. Stem cell alone might not be enough to correct or cure the SMA but could be applied as the additional therapy combined with antisense oligonucleotide in the future.

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2016-05-10 | Plastin 3 Expression Does Not Modify Spinal Muscular Atrophy Severity in the ∆7 SMA Mouse.

Spinal muscular atrophy is caused by loss of the SMN1 gene and retention of SMN2. The SMN2 copy number inversely correlates with phenotypic severity and is a modifier of disease outcome. The SMN2 gene essentially differs from SMN1 by a single nucleotide in exon 7 that modulates the incorporation of exon 7 into the final SMN transcript. The majority of the SMN2 transcripts lack exon 7 and this leads to a SMN protein that does not effectively oligomerize and is rapidly degraded. However the SMN2 gene does produce some full-length SMN and the SMN2 copy number along with how much full-length SMN the SMN2 gene makes correlates with severity of the SMA phenotype. However there are a number of discordant SMA siblings that have identical haplotypes and SMN2 copy number yet one has a milder form of SMA. It has been suggested that Plastin3 (PLS3) acts as a sex specific phenotypic modifier where increased expression of PLS3 modifies the SMA phenotype in females. To test the effect of PLS3 overexpression we have over expressed full-length PLS3 in SMA mice. To ensure no disruption of functionality or post-translational processing of PLS3 we did not place a tag on the protein. PLS3 protein was expressed under the Prion promoter as we have shown previously that SMN expression under this promoter can rescue SMA mice. High levels of PLS3 mRNA were expressed in motor neurons along with an increased level of PLS3 protein in total spinal cord, yet there was no significant beneficial effect on the phenotype of SMA mice. Specifically, neither survival nor the fundamental electrophysiological aspects of the neuromuscular junction were improved upon overexpression of PLS3 in neurons.

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