Review of Cerliponase Alfa: Recombinant Human Enzyme Replacement Therapy for Late-Infantile Neuronal Ceroid Lipofuscinosis Type 2

Intravitreal enzyme replacement for inherited retinal diseases

PURPOSE OF REVIEW

This paper provides an update on intravitreal (IVT) enzyme replacement therapy (ERT) in metabolic retinal diseases; particularly neuronal ceroid lipofuscinosis type 2 (CLN2) also known as Batten disease.

RECENT FINDINGS

ERT is being explored in CLN2 related Batten disease, a fatal neurodegenerative condition associated with retinopathy and blindness that is caused by the deficiency of lysosomal enzyme TPP1. Cerliponase alfa, a recombinant human tripeptidyl-peptidase1 (rhTPP1) administered by intraventricular infusions has been demonstrated to slow the rate of neurodegenerative decline but not retinopathy. A preclinical study of IVT rhTPP1 in a CLN2 canine model demonstrated efficacy in preserving retinal function and retinal morphology shown on histology. More recently, intravitreal (IVT) administration of rhTPP1 was reported in a first-in-human compassionate use study. Patients received 12-18 months of 8-weekly IVT ERT (0.2 mg rhTPP-1 in 0.05 ml) in one eye. No significant ocular adverse reactions were reported. Treatment decreased the rate of retinal thinning but modestly.

SUMMARY

The evidence suggests that IVT ERT with rhTPP1 may be a safe and effective treatment for CLN2 retinopathy. However, the optimal dosage and frequency to achieve the best possible outcomes requires further investigation as does patient selection.

From diagnosis to treatment in genetic epilepsies: Implementation of precision medicine in real-world clinical practice

The implementation of whole exome sequencing (WES) has had a major impact on the diagnostic yield of genetic testing in individuals with epilepsy. The identification of a genetic etiology paves the way to precision medicine: an individualized treatment approach, based on the disease pathophysiology. The aim of this retrospective cohort study was to: (1) determine the diagnostic yield of WES in a heterogeneous cohort of individuals with epilepsy referred for genetic testing in a real-world clinical setting, (2) investigate the influence of epilepsy characteristics on the diagnostic yield, (3) determine the theoretical yield of treatment changes based on genetic diagnosis and (4) explore the barriers to implementation of precision medicine. WES was performed in 247 individuals with epilepsy, aged between 7 months and 68 years. In 34/247 (14 %) a (likely) pathogenic variant was identified. In 7/34 (21 %) of these individuals the variant was found using a HPO-based filtering. Diagnostic yield was highest for individuals with an early onset of epilepsy (39 %) or in those with a developmental and epileptic encephalopathy (34 %). Precision medicine was a theoretical possibility in 20/34 (59 %) of the individuals with a (likely) pathogenic variant but implemented in only 11/34 (32 %). The major barrier to implementation of precision treatment was the limited availability or reimbursement of a given drug. These results confirm the potential impact of genetic analysis on treatment choices, but also highlight the hurdles to the implementation of precision medicine. To optimize precision medicine in real-world practice, additional endeavors are needed: unifying definitions of precision medicine, establishment of publicly accessible databases that include data on the functional effect of gene variants, increasing availability and reimbursement of precision therapeutics, and broadening access to innovative clinical trials.

Acidified drinking water improves motor function, prevents tremors and changes disease trajectory in Cln2R207X mice, a model of late infantile Batten disease

Batten disease is a group of mostly pediatric neurodegenerative lysosomal storage disorders caused by mutations in the CLN1-14 genes. We have recently shown that acidified drinking water attenuated neuropathological changes and improved motor function in the Cln1R151X and Cln3-/- mouse models of infantile CLN1 and juvenile CLN3 diseases. Here we tested if acidified drinking water has beneficial effects in Cln2R207X mice, a nonsense mutant model of late infantile CLN2 disease. Cln2R207X mice have motor deficits, muscle weakness, develop tremors, and die prematurely between 4 and 6 months of age. Acidified water administered to Cln2R207X male mice from postnatal day 21 significantly improved motor function, restored muscle strength and prevented tremors as measured at 3 months of age. Acidified drinking water also changed disease trajectory, slightly delaying the death of Cln2R207X males and females. The gut microbiota compositions of Cln2R207X and wild-type male mice were markedly different and acidified drinking water significantly altered the gut microbiota of Cln2R207X mice. This suggests that gut bacteria might contribute to the beneficial effects of acidified drinking water. Our study demonstrates that drinking water is a major environmental factor that can alter disease phenotypes and disease progression in rodent disease models.

Inborn Errors of Metabolism with Ataxia: Current and Future Treatment Options

A number of hereditary ataxias are caused by inborn errors of metabolism (IEM), most of which are highly heterogeneous in their clinical presentation. Prompt diagnosis is important because disease-specific therapies may be available. In this review, we offer a comprehensive overview of metabolic ataxias summarized by disease, highlighting novel clinical trials and emerging therapies with a particular emphasis on first-in-human gene therapies. We present disease-specific treatments if they exist and review the current evidence for symptomatic treatments of these highly heterogeneous diseases (where cerebellar ataxia is part of their phenotype) that aim to improve the disease burden and enhance quality of life. In general, a multimodal and holistic approach to the treatment of cerebellar ataxia, irrespective of etiology, is necessary to offer the best medical care. Physical therapy and speech and occupational therapy are obligatory. Genetic counseling is essential for making informed decisions about family planning.

Clinical and genetic characterization of neuronal ceroid lipofuscinoses (NCLs) in 29 Iranian patients: identification of 11 novel mutations

Neuronal ceroid lipofuscinoses (NCLs) are neurodegenerative lysosomal storage diseases which are considered among the most frequent causes of dementia in childhood worldwide This study aimed to identify the gene variants, molecular etiologies, and clinical features in 23 unrelated Iranian families with NCL. In total, 29 patients with neuronal ceroid lipofuscinoses (NCLs), diagnosed based on clinical manifestations, MRI neuroimaging, and electroencephalography (EEG), were recruited for this study. Through whole-exome sequencing (WES), functional prediction, Sanger sequencing, and segregation analysis, we found that 12 patients (41.3%) with mutations in the CLN6 gene, 7 patients (24%) with the TPP1 (CLN2) gene variants, and 4 patients (13.7%) with mutations in the MFSD8 (CLN7) gene. Also, mutations in each of the CLN3 and CLN5 genes were detected in 2 cases and mutations of each PPT1 (CLN1) and CLN8 gene were observed in only 1 separate patient. We identified 18 different mutations, 11 (61%) of which are novel, never have been reported before, and the others have been previously described. The gene variants identified in this study expand the number of published clinical cases and the variant frequency spectrum of the neuronal ceroid lipofuscinoses (NCLs) genes; moreover, the identification of these variants supplies foundational clues for future NCL diagnosis and therapy.

Long-term progression of retinal degeneration in a preclinical model of CLN7 Batten disease as a baseline for testing clinical therapeutics

BACKGROUND

Batten disease is characterized by cognitive and motor impairment, retinal degeneration, and seizures leading to premature death. Recent studies have shown efficacy for a gene therapy approach for CLN7 Batten disease. This gene therapy approach is promising to treat cognitive and motor impairment, but is not likely to delay vision loss. Additionally, the natural progression of retinal degeneration in CLN7 Batten disease patients is not well-known.

METHODS

We performed visual examinations on five patients with CLN7 Batten disease and found that patients were far progressed in degeneration within their first five years of life. To better understand the disease progression, we characterized the retina of a preclinical mouse model of CLN7 Batten disease, through the age at which mice present with paralysis and premature death.

FINDINGS

We found that this preclinical model shows signs of photoreceptor to bipolar synaptic defects early, and displays rod-cone dystrophy with late loss of bipolar cells. This vision loss could be followed not only via histology, but using clinical live imaging similar to that used in human patients.

INTERPRETATION

Natural history studies of rare paediatric neurodegenerative conditions are complicated by the rapid degeneration and limited availability of patients. Characterization of degeneration in the preclinical model allows for future experiments to better understand the mechanisms underlying the retinal disease progression in order to find therapeutics to treat patients, as well as to evaluate these therapeutic options for future human clinical trials.

FUNDING

Van Sickle Family Foundation Inc., NIHP30EY030413, Morton Fichtenbaum Charitable Trust and 5T32GM131945-03.

Characterization of neurological disease progression in a canine model of CLN5 neuronal ceroid lipofuscinosis

Golden Retriever dogs with a frameshift variant in CLN5 (c.934_935delAG) suffer from a progressive neurodegenerative disorder analogous to the CLN5 form of neuronal ceroid lipofuscinosis (NCL). Five littermate puppies homozygous for the deletion allele were identified prior to the onset of disease signs. Studies were performed to characterize the onset and progression of the disease in these dogs. Neurological signs that included restlessness, unwillingness to cooperate with the handlers, and proprioceptive deficits first became apparent at approximately 12 months of age. The neurological signs progressed over time and by 21 to 23 months of age included general proprioceptive ataxia, menace response deficits, aggressive behaviors, cerebellar ataxia, intention tremors, decreased visual tracking, seizures, cognitive decline, and impaired prehension. Due to the severity of these signs, the dogs were euthanized between 21 and 23 months of age. Magnetic resonance imaging revealed pronounced progressive global brain atrophy with a more than sevenfold increase in the volume of the ventricular system between 9.5 and 22.5 months of age. Accompanying this atrophy were pronounced accumulations of autofluorescent inclusions throughout the brain and spinal cord. Ultrastructurally, the contents of these inclusions were found to consist primarily of membrane‐like aggregates. Inclusions with similar fluorescence properties were present in cardiac muscle. Similar to other forms of NCL, the affected dogs had low plasma carnitine concentrations, suggesting impaired carnitine biosynthesis. These data on disease progression will be useful in future studies using the canine model for therapeutic intervention studies.

A survival analysis of ventricular access devices for delivery of cerliponase alfa

OBJECTIVE

Late infantile neuronal ceroid lipofuscinosis type 2 (CLN2) is a rare autosomal recessive disease caused by tripeptidyl peptidase 1 enzyme deficiency. At the authors' center, the medication cerliponase alfa is administered every 2 weeks via the intracerebroventricular (ICV) route. This requires the placement of a ventricular access device (VAD) or reservoir and frequent percutaneous punctures of this device over the child's lifetime. In this study, the authors audited the longevity and survival of these VADs and examined the causes of device failure.

METHODS

A single-center survival analysis of VAD insertions and revisions (January 2014 through June 2020) was conducted. All children received cerliponase alfa infusions through a VAD. Patient characteristics and complications were determined from a prospectively maintained surgical database and patient records. For the VAD survival analysis, the defined endpoint was when the device was removed or changed. Reservoir survival was assessed using Kaplan-Meier curves and the log-rank (Cox-Mantel) test.

RESULTS

A total of 17 patients had VADs inserted for drug delivery; median (range) age at first surgery was 4 years 4 months (1 year 8 months to 15 years). Twenty-six VAD operations (17 primary insertions and 9 revisions) were required among these 17 patients. Twelve VAD operations had an associated complication, including CSF infection (n = 6) with Propionibacterium and Staphylococcus species being the most prevalent organisms, significant surgical site swelling preventing infusion (n = 3), leakage/wound breakdown (n = 2), and catheter obstruction (n = 1). There were no complications or deaths associated with VAD insertion. The median (interquartile range) number of punctures was 59.5 (7.5-82.0) for unrevised VADs (n = 17) versus 2 (6-87.5) for revised VADs (n = 9) (p = 0.70). The median survival was 301 days for revisional reservoirs (n = 9) versus 2317 days for primary inserted reservoirs (n = 17) (p = 0.019).

CONCLUSIONS

In the context of the current interest in intrathecal drug delivery for rare metabolic disorders, the need for VADs is likely to increase. Auditing the medium- to long-term outcomes associated with these devices will hopefully result in their wider application and may have potential implications on the development of new VAD technologies. These results could also be used to counsel parents prior to commencement of therapy and VAD implantation.

The LINCE Project: A Pathway for Diagnosing NCL2 Disease

INTRODUCTION

Neuronal Ceroid Lipofuscinosis (NCL) comprises a clinically and genetically heterogeneous group of 13 neurodegenerative lysosomal storage disorders. Neuronal Ceroid lipofuscinosis type 2 disease (NCL2), caused by the deficient lysosomal enzyme tripeptidyl peptidase 1 (TPP1), is the only one with an approved enzyme replacement treatment (ERT). Early initiation of ERT appears to modify significantly the natural history of the disease. We aimed to shorten the time to diagnosis of NCL2.

METHODS

In March 2017, we started per first time in Spain a selective screening program, the LINCE project, in pediatric patients with clinical symptoms compatible with NCL2 disease. The program covered the whole country. We distributed kits to pediatricians with the necessary material to assess patients. All samples in this study were received within one week of collection. Enzymatic activity determined on dried blood spots was the main method used to screen for TPP1 and palmitoyl protein thioesterase 1 (PPT1) for the differential diagnosis with neuronal ceroid lipofuscinosis type 1 (NCL1).

RESULTS

Over a period of three years, we received 71 samples. The analysis was minimally invasive, relatively cheap and fast-executing. Three cases identified as a direct result of the selective screening strategy were confirmed by genetic study of NCL2 disease with a median age of 4.5 years. Our screening method has a specificity of 100%, and, with the absence to date of false negatives. We did not detect any NCL1-positive cases.

CONCLUSIONS

LINCE proved to be a simple, useful, and reliable tool for the diagnosis of NCL2, enabling clinicians to diagnose NCL2 faster. The presence of NCL2-positive cases in our population and availability of treatment may facilitate the inclusion of NCL2 in neonatal screening programs for early diagnosis.

Ocular Manifestations of Neuronal Ceroid Lipofuscinoses

Neuronal ceroid lipofuscinoses (NCLs) are a group of rare neurodegenerative storage disorders associated with devastating visual prognosis, with an incidence of 1/1,000,000 in the United States and comparatively higher incidence in European countries. The pathophysiological mechanisms causing NCLs occur due to enzymatic or transmembrane defects in various sub-cellular organelles including lysosomes, endoplasmic reticulum, and cytoplasmic vesicles. NCLs are categorized into different types depending upon the underlying cause i.e., soluble lysosomal enzyme deficiencies or non-enzymatic deficiencies (functions of identified proteins), which are sub-divided based on an axial classification system. In this review, we have evaluated the current evidence in the literature and reported the incidence rates, underlying mechanisms and currently available management protocols for these rare set of neuroophthalmological disorders. Additionally, we also highlighted the potential therapies under development that can expand the treatment of these rare disorders beyond symptomatic relief.

Presymptomatic treatment of classic late-infantile neuronal ceroid lipofuscinosis with cerliponase alfa

Background

Neuronal ceroid lipofuscinosis type 2 (CLN2 disease) is a rare rapidly progressive neurodegenerative disorder, resulting in early death. Intracerebroventricular enzyme replacement therapy (ERT) with cerliponase alfa is now available and has shown to delay disease progression in symptomatic patients. It is yet unknown if cerliponase alfa can prevent disease onset in presymptomatic patients.

Results

We evaluated the effect of 2 years of intracerebroventricular ERT in two siblings with CLN2 disease, one symptomatic (age 47 months) and one presymptomatic (age 23 months) at treatment start, using the CLN2 Clinical Rating Scale (CLN2 CRS), Gross Motor Function Measure-66 (GMFM-66) for motor function, Bayley Scales of Infant and Toddler Development, 3rd Edition, Dutch (BSID-III-NL) for neurocognitive development, brain MRI, and visual evoked potentials (VEP), electroretinogram (ERG) and retinoscopy for visual function. On the CLN2 CRS patient 1 showed a decline from 3 to 2 in the combined motor and language score due to regression in language use (CLN2 CRS total score after 2 years of treatment: 8), whereas a decline of 2 or more points in the combined motor and language score would be expected without treatment. Patient 2 retained the maximum score of 3 in all 4 subdomains (CLN2 CRS total score after 2 years of treatment: 12). The GMFM-66 total score declined from 46 to 39 in patient 1 and showed an age-appropriate increase from 66 to 84 in patient 2. Cognitive-developmental age decreased from 24 to 11 months in patient 1, whereas an increase in cognitive-developmental age from 21 to 39 months was seen in patient 2. Cerebral and cerebellar atrophy observed on MRI in patient 1 at age 42 months (before treatment) was not observed in patient 2 at age 48 months (after 2 years of treatment).

Conclusion

We show that cerliponase alfa is able to delay the onset of symptoms when treatment is started in a presymptomatic stage of CLN2 disease. Our results advocate the start of treatment at an early age before symptom onset, but should be confirmed in a larger cohort study.

Neuronal ceroid lipofuscinosis: genetic and phenotypic spectrum of 14 patients from Turkey

INTRODUCTION AND PURPOSE

Neuronal ceroid lipofuscinoses (NCLs) is a group of congenital metabolic diseases where the neurodegenerative process with the accumulation of ceroid and lipofuscin autofluorescent storage materials is at the forefront. According to the age of presentation, NCLs are classified as congenital, infantile (INCL), late infantile (LINCL), juvenile (JNCL), and adult (ANCL) NCLs. In our study, it was aimed to discuss the clinical and molecular characteristics of our patients diagnosed with NCL.

MATERIAL AND METHOD

This is a descriptive cross-sectional study which was conducted in 14 patients from 10 unrelated families who were diagnosed with different types of NCL based on clinical presentation, neuroimaging, biochemical measurements, and molecular analyses, at the department of pediatric metabolism between June 2015 and June 2020.

RESULTS

A total of 14 patients were diagnosed with different types of NCL. Of those, 4 patients were diagnosed with NCL7 (4/14; 30%), 3/14 (23%) with NCL1, 3/14 (23%) with NCL2, 2/14 (14.2%) with NCL13, and 1/14 (7.1%) with NCL10. Eleven pathogenic variants were detected, 5 of which are novel (c.721G>T [p.Gly241Ter] and c.301G>C [p.Ala146Pro] in MFDS8 gene; c.316C>T [p.Gln106Ter] in PPT1 gene; c.341C>T [p.Ala114Val] in TPP1 gene; c.686A>T [p.Glu229Val] in CTSD gene) CONCLUSION: This study is one of the pioneer comprehensive researches from Turkey that provides information about disease-causing variants and clinical presentation of different and rare types of NCLs. The identification of novel variants and phenotypic expansion is important for genetic counselling in Turkey and expected to improve understanding of NCLs.

Intracranial delivery of AAV9 gene therapy partially prevents retinal degeneration and visual deficits in CLN6-Batten disease mice

Batten disease is a family of rare, fatal, neuropediatric diseases presenting with memory/learning decline, blindness, and loss of motor function. Recently, we reported the use of an AAV9-mediated gene therapy that prevents disease progression in a mouse model of CLN6-Batten disease (Cln6 ^nclf ), restoring lifespans in treated animals. Despite the success of our viral-mediated gene therapy, the dosing strategy was optimized for delivery to the brain parenchyma and may limit the therapeutic potential to other disease-relevant tissues, such as the eye. Here, we examine whether cerebrospinal fluid (CSF) delivery of scAAV9.CB.CLN6 is sufficient to ameliorate visual deficits in Cln6 ^nclf mice. We show that intracerebroventricular (i.c.v.) delivery of scAAV9.CB.CLN6 completely prevents hallmark Batten disease pathology in the visual processing centers of the brain, preserving neurons of the superior colliculus, thalamus, and cerebral cortex. Importantly, i.c.v.-delivered scAAV9.CB.CLN6 also expresses in many cells throughout the central retina, preserving many photoreceptors typically lost in Cln6 ^nclf mice. Lastly, scAAV9.CB.CLN6 treatment partially preserved visual acuity in Cln6 ^nclf mice as measured by optokinetic response. Taken together, we report the first instance of CSF-delivered viral gene reaching and rescuing pathology in both the brain parenchyma and retinal neurons, thereby partially slowing visual deterioration.

The improvement in diagnosis and epilepsy managing in children with progressive myoclonus epilepsy during the last decade - A tertiary center experience in cohort of 51 patients

The aim of the study was to explore whether diagnosis and managing children with progressive myoclonus epilepsy (PME) were improved during the last decade.

METHODS

The retrospective study included children with PME treated in the Institute during the last 25 years. Investigation time was divided in two periods (groups): before December 2010 (the first group) and after this period up to December 2019 (the second group). Inclusion criteria are as follows: patients aged from 0.2-18 years and with PME. Evaluated parameters are etiology, age at seizure onset, diagnosis delay, epilepsy phenotype, and, as a measure of epilepsy control - status epilepticus (SE) frequency and recurrence rate. Statistical analysis included the following tests: Chi-Square, Mann-Whitney, and analysis of variance (ANOVA), using SPSS version 25.

RESULTS

The study included 51 patients, 27 in the first, and 24 in the second group. The underlying diseases were: neuronal ceroid lipofuscinosis (NCL; 30), Gaucher (5), Niemann-Pick (4), mitochondrial (4), Lafora (3), Krabbe (2), and KCNC1 gene mutation (2). The average duration from initial symptoms to diagnosis was 3.2 ± 3 years (first group) vs. 1.4 ± 0.9 years (second). Both SE frequency rate (55.5% vs. 37.5%) and recurrence rate (66.7% vs. 22.2%) were higher in the first group, showing tendency towards, but not statistically significant difference.

CONCLUSION

The diagnosis and epilepsy managing children with PME were improved during the last decade. Earlier genetic diagnosis, appropriate antiseizure medications, education of parents/caregivers of children in high risk for SE, and availability of effective prehospital rescue medications contributed to significantly decreased frequency and recurrence rate of SE.

Neuronal Ceroid Lipofuscinosis: Clinical and Laboratory Profile in Children from Tertiary Care Centre in South India

Neuronal ceroid Lipofuscinosis (NCL), inherited disorders of lysosomal storage disorders, constitute the most common progressive encephalopathies with an incidence of 1.3 to 7 in 100,000 live births. We reported clinical, electrophysiological, radiological, ultrastructural, and molecular genetic features of NCL. This is a retrospective review, in a tertiary care center from January 2016 to December 2019. All children with clinical features of NCL and confirmed by pathogenic mutation and/or enzyme assay were included. A total of 60 children (male:female = 3:1) were studied. The commonest type was CLN 2 (41.7%). Neuroregression, seizures, and ataxia were present in all cases. Retinal arterial attenuation was seen in 38.33% cases. Magnetic resonance imaging (MRI) brain was abnormal in all patients, thalamic and caudate nucleus atrophy common in CLN1 (62%). Electroencephalography was abnormal in all children, but photoparoxysmal response at low intermittent photic stimulation frequencies was seen in four children of CLN2. Electron microscopy done in 43 children revealed abnormal inclusions in 20 (46.52%) children. Enzyme study showed low levels in 36 (78%) out of 46 cases. Of these, 21 had low tripeptidyl peptidase and 15 had low palmitoyl protein thioesterase levels. Molecular testing done in 26 cases showed pathogenic variant in 23 (88%) cases. Infantile onset with thalamic atrophy on MRI is common in CLN1 and refractory epilepsy, visual impairment and specific EEG changes are common in CLN2. These features are helpful in selecting enzyme assay for CLN1 versus CLN2. Electron microscopy helped in the diagnosis and genetic testing in subtyping. Thus, a multimode approach played a role in the diagnosis of NCL.

Molecular networking in the neuronal ceroid lipofuscinoses: insights from mammalian models and the social amoeba Dictyostelium discoideum

The neuronal ceroid lipofuscinoses (NCLs), commonly known as Batten disease, belong to a family of neurological disorders that cause blindness, seizures, loss of motor function and cognitive ability, and premature death. There are 13 different subtypes of NCL that are associated with mutations in 13 genetically distinct genes (CLN1-CLN8, CLN10-CLN14). Similar clinical and pathological profiles of the different NCL subtypes suggest that common disease mechanisms may be involved. As a result, there have been many efforts to determine how NCL proteins are connected at the cellular level. A main driving force for NCL research has been the utilization of mammalian and non-mammalian cellular models to study the mechanisms underlying the disease. One non-mammalian model that has provided significant insight into NCL protein function is the social amoeba Dictyostelium discoideum. Accumulated data from Dictyostelium and mammalian cells show that NCL proteins display similar localizations, have common binding partners, and regulate the expression and activities of one another. In addition, genetic models of NCL display similar phenotypes. This review integrates findings from Dictyostelium and mammalian models of NCL to highlight our understanding of the molecular networking of NCL proteins. The goal here is to help set the stage for future work to reveal the cellular mechanisms underlying the NCLs.