Clinical Trial and Postmarketing Safety of Onasemnogene Abeparvovec Therapy

INTRODUCTION: This is the first description of safety data for intravenous onasemnogene abeparvovec, the only approved systemically administered gene-replacement therapy for spinal muscular atrophy. OBJECTIVE: We comprehensively assessed the safety of intravenous onasemnogene abeparvovec from preclinical studies, clinical studies, and postmarketing data. METHODS: Single-dose toxicity studies were performed in neonatal mice and juvenile or neonatal cynomolgus nonhuman primates (NHPs). Data presented are from a composite of preclinical studies, seven clinical trials, and postmarketing sources (clinical trials, n = 102 patients; postmarketing surveillance, n = 665 reported adverse event [AE] cases). In clinical trials, safety was assessed through AE monitoring, vital-sign and cardiac assessments, laboratory evaluations, physical examinations, and concomitant medication use. AE reporting and available objective clinical data from postmarketing programs were evaluated. RESULTS: The main target organs of toxicity in mice were the heart and liver. Dorsal root ganglia (DRG) inflammation was observed in NHPs. Patients exhibited no evidence of sensory neuropathy upon clinical examination. In clinical trials, 101/102 patients experienced at least one treatment-emergent AE. In total, 50 patients experienced serious AEs, including 11 considered treatment related. AEs consistent with hepatotoxicity resolved with prednisolone in clinical trials. Transient decreases in mean platelet count were detected but were without bleeding complications. Thrombotic microangiopathy (TMA) was observed in the postmarketing setting. No evidence of intracardiac thrombi was observed for NHPs or patients. CONCLUSIONS: Risks associated with onasemnogene abeparvovec can be anticipated, monitored, and managed. Hepatotoxicity events resolved with prednisolone. Thrombocytopenia was transient. TMA may require medical intervention. Important potential risks include cardiac AEs and DRG toxicity

Clinical trial and postmarketing safety of onasemnogene abeparvovec therapy

INTRODUCTION: This is the first description of safety data for intravenous onasemnogene abeparvovec, the only approved systemically administered gene-replacement therapy for spinal muscular atrophy. OBJECTIVE: We comprehensively assessed the safety of intravenous onasemnogene abeparvovec from preclinical studies, clinical studies, and postmarketing data. METHODS: Single-dose toxicity studies were performed in neonatal mice and juvenile or neonatal cynomolgus nonhuman primates (NHPs). Data presented are from a composite of preclinical studies, seven clinical trials, and postmarketing sources (clinical trials, n = 102 patients; postmarketing surveillance, n = 665 reported adverse event [AE] cases). In clinical trials, safety was assessed through AE monitoring, vital-sign and cardiac assessments, laboratory evaluations, physical examinations, and concomitant medication use. AE reporting and available objective clinical data from postmarketing programs were evaluated. RESULTS: The main target organs of toxicity in mice were the heart and liver. Dorsal root ganglia (DRG) inflammation was observed in NHPs. Patients exhibited no evidence of sensory neuropathy upon clinical examination. In clinical trials, 101/102 patients experienced at least one treatment-emergent AE. In total, 50 patients experienced serious AEs, including 11 considered treatment related. AEs consistent with hepatotoxicity resolved with prednisolone in clinical trials. Transient decreases in mean platelet count were detected but were without bleeding complications. Thrombotic microangiopathy (TMA) was observed in the postmarketing setting. No evidence of intracardiac thrombi was observed for NHPs or patients. CONCLUSIONS: Risks associated with onasemnogene abeparvovec can be anticipated, monitored, and managed. Hepatotoxicity events resolved with prednisolone. Thrombocytopenia was transient. TMA may require medical intervention. Important potential risks include cardiac AEs and DRG toxicity

Homologous Recombination Mediates Functional Recovery of Dysferlin Deficiency following AAV5 Gene Transfer

The dysferlinopathies comprise a group of untreatable muscle disorders including limb girdle muscular dystrophy type 2B, Miyoshi myopathy, distal anterior compartment syndrome, and rigid spine syndrome. As with other forms of muscular dystrophy, adeno-associated virus (AAV) gene transfer is a particularly auspicious treatment strategy, however the size of the DYSF cDNA (6.5 kb) negates packaging into traditional AAV serotypes known to express well in muscle (i.e. rAAV1, 2, 6, 8, 9). Potential advantages of a full cDNA versus a mini-gene include: maintaining structural-functional protein domains, evading protein misfolding, and avoiding novel epitopes that could be immunogenic. AAV5 has demonstrated unique plasticity with regards to packaging capacity and recombination of virions containing homologous regions of cDNA inserts has been implicated in the generation of full-length transcripts. Herein we show for the first time in vivo that homologous recombination following AAV5.DYSF gene transfer leads to the production of full length transcript and protein. Moreover, gene transfer of full-length dysferlin protein in dysferlin deficient mice resulted in expression levels sufficient to correct functional deficits in the diaphragm and importantly in skeletal muscle membrane repair. Intravascular regional gene transfer through the femoral artery produced high levels of transduction and enabled targeting of specific muscle groups affected by the dysferlinopathies setting the stage for potential translation to clinical trials. We provide proof of principle that AAV5 mediated delivery of dysferlin is a highly promising strategy for treatment of dysferlinopathies and has far-reaching implications for the therapeutic delivery of other large genes

The Clinical Outcome Study for dysferlinopathy: An international multicenter study

Objective: To describe the baseline clinical and functional characteristics of an international cohort of 193 patients with dysferlinopathy. Methods: The Clinical Outcome Study for dysferlinopathy (COS) is an international multicenter study of this disease, evaluating patients with genetically confirmed dysferlinopathy over 3 years. We present a cross-sectional analysis of 193 patients derived from their baseline clinical and functional assessments. Results: There is a high degree of variability in disease onset, pattern of weakness, and rate of progression. No factor, such as mutation class, protein expression, or age at onset, accounted for this variability. Among patients with clinical diagnoses of Miyoshi myopathy or limb-girdle muscular dystrophy, clinical presentation and examination was not strikingly different. Respiratory impairment and cardiac dysfunction were observed in a minority of patients. A substantial delay in diagnosis was previously common but has been steadily reducing, suggesting increasing awareness of dysferlinopathies. Conclusions: These findings highlight crucial issues to be addressed for both optimizing clinical care and planning therapeutic trials in dysferlinopathy. This ongoing longitudinal study will provide an opportunity to further understand patterns and variability in disease progression and form the basis for trial design

Assessing Dysferlinopathy Patients Over Three Years With a New Motor Scale

The Jain COS Consortium.[Objective] Dysferlinopathy is a muscular dystrophy with a highly variable clinical presentation and currently unpredictable progression. This variability and unpredictability presents difficulties for prognostication and clinical trial design. The Jain Clinical Outcomes Study of Dysferlinopathy aims to establish the validity of the North Star Assessment for Limb Girdle Type Muscular Dystrophies (NSAD) scale and identify factors that influence the rate of disease progression using NSAD.[Methods] We collected a longitudinal series of functional assessments from 187 patients with dysferlinopathy over 3 years. Rasch analysis was used to develop the NSAD, a motor performance scale suitable for ambulant and nonambulant patients. Generalized estimating equations were used to evaluate the impact of patient factors on outcome trajectories.[Results] The NSAD detected significant change in clinical progression over 1 year. The steepest functional decline occurred during the first 10 years after symptom onset, with more rapid decline noted in patients who developed symptoms at a younger age (p = 0.04). The most rapidly deteriorating group over the study was patients 3 to 8 years post symptom onset at baseline.[Interpretation] The NSAD is the first validated limb girdle specific scale of motor performance, suitable for use in clinical practice and clinical trials. Longitudinal analysis showed it may be possible to identify patient factors associated with greater functional decline both across the disease course and in the short-term for clinical trial preparation. Through further work and validation in this cohort, we anticipate that a disease model incorporating functional performance will allow for more accurate prognosis for patients with dysferlinopathy. ANN NEUROL 2021;89:967–978The estimated US $4 million needed to fund this study was provided by the Jain Foundation. (www.jain-foundation.org) The Jain COS consortium would like to thank the study participants and their families for their invaluable contribution. The John Walton Centre Muscular Dystrophy Research Centre is part of the MRC Centre for Neuromuscular Diseases (Grant number MR/K000608/1).Peer reviewe

Expanding the muscle imaging spectrum in dysferlinopathy: description of an outlier population from the classical MRI pattern

© 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)Dysferlinopathy is a muscle disease characterized by a variable clinical presentation and is caused by mutations in the DYSF gene. The Jain Clinical Outcome Study for Dysferlinopathy (COS) followed the largest cohort of patients (n=187) with genetically confirmed dysferlinopathy throughout a three-year natural history study, in which the patients underwent muscle function tests and muscle magnetic resonance imaging (MRI). We previously described the pattern of muscle pathology in this population and established a series of imaging criteria for diagnosis. In this paper, we describe the muscle imaging and clinical features of a subgroup of COS participants whose muscle imaging results did not completely meet the diagnostic criteria. We reviewed 184 T1-weighted (T1w) muscle MRI scans obtained at the baseline visit of the COS study, of which 106 were pelvic and lower limb only and 78 were whole-body scans. We identified 116 of the 184 patients (63%) who did not meet at least one of the established imaging criteria. The highest number found of unmet criteria was four per patient. We identified 24 patients (13%) who did not meet three or more of the nine established criteria and considered them as “outliers”. The most common unmet criterion (27.3% of cases) was the adductor magnus being equally or more affected than the adductor longus. We compared the genetic, demographic, clinical and muscle function data of the outlier patients with those who met the established criteria and observed that the outlier patients had an age of disease onset that was significantly older than the whole group (29.3 vs 20.5 years, p=0.0001). This study expands the phenotypic muscle imaging spectrum of patients with dysferlinopathy and can help to guide the diagnostic process in patients with limb girdle weakness of unknown origin.The Jain Foundation provided an estimated $4 million USD to fund the COS study.Peer reviewe

Table_2_Assessing the Relationship of Patient Reported Outcome Measures With Functional Status in Dysferlinopathy: A Rasch Analysis Approach.docx

Appendix B. Coinvestigators - The Jain COS Consortium.Dysferlinopathy is a muscular dystrophy with a highly variable functional disease progression in which the relationship of function to some patient reported outcome measures (PROMs) has not been previously reported. This analysis aims to identify the suitability of PROMs and their association with motor performance.Two-hundred and four patients with dysferlinopathy were identified in the Jain Foundation's Clinical Outcome Study in Dysferlinopathy from 14 sites in 8 countries. All patients completed the following PROMs: Individualized Neuromuscular Quality of Life Questionnaire (INQoL), International Physical Activity Questionnaire (IPAQ), and activity limitations for patients with upper and/or lower limb impairments (ACTIVLIMs). In addition, nonambulant patients completed the Egen Klassifikation Scale (EK). Assessments were conducted annually at baseline, years 1, 2, 3, and 4. Data were also collected on the North Star Assessment for Limb Girdle Type Muscular Dystrophies (NSAD) and Performance of Upper Limb (PUL) at these time points from year 2. Data were analyzed using descriptive statistics and Rasch analysis was conducted on ACTIVLIM, EK, INQoL. For associations, graphs (NSAD with ACTIVLIM, IPAQ and INQoL and EK with PUL) were generated from generalized estimating equations (GEE). The ACTIVLIM appeared robust psychometrically and was strongly associated with the NSAD total score (Pseudo R2 0.68). The INQoL performed less well and was poorly associated with the NSAD total score (Pseudo R2 0.18). EK scores were strongly associated with PUL (Pseudo R2 0.69). IPAQ was poorly associated with NSAD scores (Pseudo R2 0.09). This study showed that several of the chosen PROMs demonstrated change over time and a good association with functional outcomes. An alternative quality of life measure and method of collecting data on physical activity may need to be selected for assessing dysferlinopathy.Peer reviewe

Assessing dysferlinopathy patients over three years with a new motor scale

OBJECTIVE: Dysferlinopathy is a muscular dystrophy with a highly variable clinical presentation and currently unpredictable progression. This variability and unpredictability presents difficulties for prognostication and clinical trial design. The Jain Clinical Outcomes Study of Dysferlinopathy aims to establish the validity of the North Star Assessment for Limb Girdle Type Muscular Dystrophies (NSAD) scale and identify factors that influence the rate of disease progression using NSAD. METHODS: We collected a longitudinal series of functional assessments from 187 dysferlinopathy patients over three years. Rasch analysis was used to develop the NSAD, a motor performance scale suitable for ambulant and non-ambulant patients. Generalized estimating equations were used to evaluate the impact of patient factors on outcome trajectories. RESULTS: The NSAD detected significant change in clinical progression over 1 year. The steepest functional decline occurred during the first 10 years after symptom onset, with more rapid decline noted in patients who developed symptoms at a younger age (p = 0.04). The most rapidly deteriorating group over the study was patients 3-8 years post symptom onset at baseline. INTERPRETATION: The NSAD is the first validated limb girdle specific scale of motor performance, suitable for use in clinics practice and clinical trials. Longitudinal analysis showed it may be possible to identify patient factors associated with greater functional decline both across the disease course and in the short-term for clinical trial preparation. Through further work and validation in this cohort, we anticipate that a disease model incorporating functional performance will allow for more accurate prognosis for patients with dysferlinopathy

Translating the genomics revolution: the need for an international gene therapy consortium for monogenic diseases

Letter to the Edito