Guidelines on the diagnosis, clinical assessments, treatment and management for CLN2 disease patients

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.

A needle in a haystack? The impact of a targeted epilepsy gene panel in the identification of a treatable but rapidly progressive metabolic epilepsy: CLN2 disease

BACKGROUND

 Neuronal ceroid lipofuscinoses (NCL) are a group of autosomal recessive, inherited, lysosomal, and neurodegenerative diseases that causes progressive dementia, seizures, movement disorders, language delay/regression, progressive visual failure, and early death. Neuronal ceroid lipofuscinosis type 2 (CLN2), caused by biallelic pathogenic variants of the TPP1 gene, is the only NCL with an approved targeted therapy. The laboratory diagnosis of CLN2 is established through highly specific tests, leading to diagnostic delays and eventually hampering the provision of specific treatment for patients with CLN2. Epilepsy is a common and clinically-identifiable feature among NCLs, and seizure onset is the main driver for families to seek medical care.

OBJECTIVE

 To evaluate the results of the Latin America Epilepsy and Genetics Program, an epilepsy gene panel, as a comprehensive tool for the investigation of CLN2 among other genetic causes of epilepsy.

METHODS

 A total of 1,284 patients with epilepsy without a specific cause who had at least 1 symptom associated with CLN2 were screened for variants in 160 genes associated with epilepsy or metabolic disorders presenting with epilepsy through an epilepsy gene panel.

RESULTS

 Variants of the TPP1 gene were identified in 25 individuals (1.9%), 21 of them with 2 variants. The 2 most frequently reported variants were p.Arg208* and p.Asp276Val, and 2 novel variants were detected in the present study: p.Leu308Pro and c.89 + 3G > C Intron 2.

CONCLUSION

 The results suggest that these genetic panels can be very useful tools to confirm or exclude CLN2 diagnosis and, if confirmed, provide disease-specific treatment for the patients.

Peripheral retinal finding on fluorescein angiography in neuronal ceroid lipofuscinosis type 2 (CLN2)

Classically, peripheral vascular changes in the retina in patients with neuronal ceroid lipofuscinosis type 2 (CLN2) are described as vascular attenuation seen in the late stages of disease on the Weill Connell Ophthalmic Severity Score (WCOSS) staging system. We describe isolated, mild, peripheral vasculitis with peripheral arteriolar dropout identified by fluorescein angiography in patients with a WCOSS grade of stage 2. We believe this vasculitis represents an early vasodegenerative phase of disease that leads to the vascular attenuation seen in later stages of the disease.

Developmental Skills and Neurorehabilitation for Children With Batten Disease: A Retrospective Chart Review of a Comprehensive Batten Clinic

BACKGROUND

Batten disease is a rare, progressive neurogenetic disorder composed of 13 genotypes that often presents in childhood. Children present with seizures, vision loss, and developmental regression. Neurorehabilitation services (i.e., physical therapy, occupational therapy, and speech-language therapy) can help improve the quality of life for children and their families. Owing to the rarity of Batten disease, there are no standardized clinical recommendations or outcome assessments. To describe developmental profiles, current dose of neurorehabilitation, and outcome assessments used clinically for children diagnosed with Batten disease.

METHODS

Electronic medical records of 70 children with Batten disease (subtypes n = 5 CLN1; n = 25 CLN2; n = 23 CLN3; n = 17 CLN6) were reviewed (7.0 ± 3.4 years). Descriptive statistics were used to describe clinical features, developmental skills, dose of neurorehabilitation, and outcome assessment use.

RESULTS

Across CLN subtypes, most children experienced vision impairments (61%) and seizures (68%). Most children demonstrated delays in fine motor (65%), gross motor (80%), cognitive (63%), and language skills (83%). The most common frequency of neurorehabilitation was weekly (42% to 43%). Two standardized outcome assessments were used to track developmental outcomes: Peabody Developmental Motor Scales, second edition (30% of children completed this assessment) and Preschool Language Scales, fifth edition (27.4% of children completed this assessment).

CONCLUSIONS

Neurorehabilitation professionals should understand the clinical features and prognosis for children with Batten disease. The child's clinical features and family preferences should guide the rehabilitation plan of care. Future work needs to be completed to define dosing parameters and validate outcome assessments for neurorehabilitation services.

Classic and Atypical Late Infantile Neuronal Ceroid Lipofuscinosis in Latin America: Clinical and Genetic Aspects, and Treatment Outcome with Cerliponase Alfa

Introduction

Late infantile neuronal ceroid lipofuscinosis type 2 (CLN2), is a neurodegenerative autosomal recessive disease caused by TPP1 gene variants, with a spectrum of classic and atypical phenotypes. The aim of treatment is to slow functional decline as early as possible in an attempt to improve quality of life and survival. This study describes the clinical characteristics as well as the response to treatment with cerliponase alfa.

Materials and methods

A retrospective study was conducted in five Latin-American countries, using clinical records from patients with CLN2. Clinical follow-up and treatment variables are described. A descriptive and bivariate statistical analysis was performed.

Results

A total of 36 patients were observed (range of follow-up of 61-110 weeks post-treatment). At presentation, patients with the classic phenotype (n = 16) exhibited regression in language (90%), while seizures were the predominant symptom (87%) in patients with the atypical phenotype (n = 20). Median age of symptom onset and time to first specialized consultation was 3 (classical) and 7 (atypical) years, while the median time interval between onset of symptoms and treatment initiation was 4 years (classical) and 7.5 (atypical). The most frequent variant was c.827 A > T in 17/72 alleles, followed by c.622C > T in 6/72 alleles. All patients were treated with cerliponase alfa, and either remained functionally stable or had a loss of 1 point on the CLN2 scale, or up to 2 points on the Wells Cornel and Hamburg scales, when compared to pretreatment values.

Discussion and conclusion

This study reports the largest number of patients with CLN2 currently on treatment with cerliponase alfa in the world. Data show a higher frequency of patients with atypical phenotypes and a high allelic proportion of intron variants in our region. There was evidence of long intervals until first specialized consultation, diagnosis, and enzyme replacement therapy. Follow-up after the initiation of cerliponase alfa showed slower progression or stabilization of the disease, associated with adequate clinical outcomes and stable functional scores. These improvements were consistent in both clinical phenotypes.

Safety and efficacy of cerliponase alfa in children with neuronal ceroid lipofuscinosis type 2 (CLN2 disease): an open-label extension study

BACKGROUND

Cerliponase alfa is a recombinant human tripeptidyl peptidase 1 (TPP1) enzyme replacement therapy for the treatment of neuronal ceroid lipofuscinosis type 2 (CLN2 disease), which is caused by mutations in the TPP1 gene. We aimed to determine the long-term safety and efficacy of intracerebroventricular cerliponase alfa in children with CLN2 disease.

METHODS

This analysis includes cumulative data from a primary 48-week, single-arm, open-label, multicentre, dose-escalation study (NCT01907087) and the 240-week open-label extension with 6-month safety follow-up, conducted at five hospitals in Germany, Italy, the UK, and the USA. Children aged 3-16 years with CLN2 disease confirmed by genetic analysis and enzyme testing were eligible for inclusion. Treatment was intracerebroventricular infusion of 300 mg cerliponase alfa every 2 weeks. Historical controls with untreated CLN2 disease in the DEM-CHILD database were used as a comparator group. The primary efficacy outcome was time to an unreversed 2-point decline or score of 0 in the combined motor and language domains of the CLN2 Clinical Rating Scale. This extension study is registered with ClinicalTrials.gov, NCT02485899, and is complete.

FINDINGS

Between Sept 13, 2013, and Dec 22, 2014, 24 participants were enrolled in the primary study (15 female and 9 male). Of those, 23 participants were enrolled in the extension study, conducted between Feb 2, 2015, and Dec 10, 2020, and received 300 mg cerliponase alfa for a mean of 272·1 (range 162·1-300·1) weeks. 17 participants completed the extension and six discontinued prematurely. Treated patients were significantly less likely than historical untreated controls to have an unreversed 2-point decline or score of 0 in the combined motor and language domains (hazard ratio 0·14, 95% CI 0·06 to 0·33; p<0·0001). All participants experienced at least one adverse event and 21 (88%) experienced a serious adverse event; nine participants experienced intracerebroventricular device-related infections, with nine events in six participants resulting in device replacement. There were no study discontinuations because of an adverse event and no deaths.

INTERPRETATION

Cerliponase alfa over a mean treatment period of more than 5 years was seen to confer a clinically meaningful slowing of decline of motor and language function in children with CLN2 disease. Although our study does not have a contemporaneous control group, the results provide crucial insights into the effects of long-term treatment.

FUNDING

BioMarin Pharmaceutical.

Language Delay in Patients with CLN2 Disease: Could It Support Earlier Diagnosis?

Neuronal ceroid lipofuscinosis type 2 (CLN2 disease) is a rare pediatric disorder associated with rapid neurodegeneration, and premature death in adolescence. An effective enzyme replacement therapy (cerliponase alfa) has been approved that can reduce this predictable neurological decline. The nonspecific early symptoms of CLN2 disease frequently delay diagnosis and appropriate management. Seizures are generally recognized as the first presenting symptom of CLN2 disease, but emerging data show that language delay may precede this. An improved understanding of language deficits in the earliest stage of CLN2 disease may support the early identification of patients. In this article, CLN2 disease experts examine how language development is affected by CLN2 disease in their clinical practices. The authors' experiences highlighted the timings of first words and first use of sentences, and language stagnation as key features of language deficits in CLN2 disease, and how deficits in language may be an earlier sign of the disease than seizures. Potential challenges in identifying early language deficits include assessing patients with other complex needs, and recognizing that a child's language abilities are not within normal parameters given the variability of language development in young children. CLN2 disease should be considered in children presenting with language delay and/or seizures to facilitate earlier diagnosis and access to treatment that can significantly reduce morbidity.

Long-term safety and dose escalation of intracerebroventricular CLN5 gene therapy in sheep supports clinical translation for CLN5 Batten disease

CLN5 neuronal ceroid lipofuscinosis (NCL, Batten disease) is a rare, inherited fatal neurodegenerative disorder caused by mutations in the CLN5 gene. The disease is characterised by progressive neuronal loss, blindness, and premature death. There is no cure. This study evaluated the efficacy of intracerebroventricular (ICV) delivery of an adeno-associated viral vector encoding ovine CLN5 (scAAV9/oCLN5) in a naturally occurring sheep model of CLN5 disease. CLN5 affected (CLN5-/-) sheep received low, moderate, or high doses of scAAV9/oCLN5 at three disease stages. The treatment delayed disease progression, extended survival and slowed stereotypical brain atrophy in most animals. Of note, one high dose treated animal only developed mild disease symptomology and survived to 60.1 months of age, triple the natural life expectancy of an untreated CLN5-/- sheep. Eyesight was not preserved at any administration age or dosage. Histopathologic examination revealed that greater transduction efficiency was achieved through higher ICV doses, and this resulted in greater amelioration of disease pathology. Together with other pre-clinical data from CLN5-/- sheep, the safety and efficacy data from these investigational new drug (IND)-enabling studies supported the initiation of the first in-human CLN5 gene therapy clinical study using the ICV delivery route for the treatment of CLN5 NCL. Clinical Trial Registration: https://clinicaltrials.gov/, identifier NCT05228145.

Gene therapy ameliorates spontaneous seizures associated with cortical neuron loss in a Cln2R207X mouse model

Although a disease-modifying therapy for classic late infantile neuronal ceroid lipofuscinosis (CLN2 disease) exists, poor understanding of cellular pathophysiology has hampered the development of more effective and persistent therapies. Here, we investigated the nature and progression of neurological and underlying neuropathological changes in Cln2R207X mice, which carry one of the most common pathogenic mutations in human patients but are yet to be fully characterized. Long-term electroencephalography recordings revealed progressive epileptiform abnormalities, including spontaneous seizures, providing a robust, quantifiable, and clinically relevant phenotype. These seizures were accompanied by the loss of multiple cortical neuron populations, including those stained for interneuron markers. Further histological analysis revealed early localized microglial activation months before neuron loss started in the thalamocortical system and spinal cord, which was accompanied by astrogliosis. This pathology was more pronounced and occurred in the cortex before the thalamus or spinal cord and differed markedly from the staging seen in mouse models of other forms of neuronal ceroid lipofuscinosis. Neonatal administration of adeno-associated virus serotype 9-mediated gene therapy ameliorated the seizure and gait phenotypes and prolonged the life span of Cln2R207X mice, attenuating most pathological changes. Our findings highlight the importance of clinically relevant outcome measures for judging preclinical efficacy of therapeutic interventions for CLN2 disease.

The diagnostic challenges presented in a patient with neuronal ceroid lipofuscinosis type 2

Neuronal ceroid lipofuscinosis type 2 (NCL2) is a severe, continuously progressive hereditary metabolic disease for which there is an effective enzyme replacement therapy.Purpose. To study the opinions of specialists (pediatric neurologists, neurologists-epileptologists, geneticists) about the obstacles to the early diagnosis of neuronal ceroid lipofuscinosis type 2 in patients.Material and methods. The study was conducted by the method of in-depth interviews. 25 physicians dealing with NCL2 pts took part in the interview.Results. From 2000 to 2021, 45 patients with NCL2 were identified in the Russian Federation. Data on the course of the disease were obtained from 38 patients aged 3 to 11 years, of which 16 received enzyme replacement therapy. At the time of the interview, 32/38 were alive, 4/32 had died, and outcome data for 2 patients were missing. The age of onset of the first symptoms varied significantly: from 1 year 10 months to 3 years 6 months. The median age at which children were diagnosed with NCL2 was 52 months, or 4 years 5 months, but it varied from 12 to 96 months. At the time of diagnosis, in addition to epileptic seizures and delayed speech development, ataxia and loss of motor development, as well as other symptoms, were already noted. EEG was performed in 73% of all cases (with photostimulation only in 34%). MRI at an early stage of the disease was performed in only 40%. Only 46% of patients receive (or have ever received) enzyme replacement therapy. In 41% of cases, enzyme replacement therapy was not prescribed due to the long-term diagnosis of NCL2, which led to a palliative status and refusal of the patients’ parents from therapy.Conclusion. Early diagnosis of NCL2 is difficult due to the non-specificity of the first symptoms, as well as due to the poor awareness of doctors about the disease and the main methods of its diagnosis, which leads to late prescribing of enzyme replacement therapy.

Buffy Coat Score as a Biomarker of Treatment Response in Neuronal Ceroid Lipofuscinosis Type 2

The introduction of intracerebroventricular (ICV) enzyme replacement therapy (ERT) for treatment of neuronal ceroid lipofuscinosis type 2 (CLN2) disease has produced dramatic improvements in disease management. However, assessments of therapeutic effect for ICV ERT are limited to clinical observational measures, namely the CLN2 Clinical Rating Scale, a subjective measure of motor and language performance. There is a need for an objective biomarker to enable assessments of disease progression and response to treatment. To address this, we investigated whether the proportion of cells with abnormal storage inclusions on electron microscopic examination of peripheral blood buffy coats could act as a biomarker of disease activity in CLN2 disease. We conducted a prospective longitudinal analysis of six patients receiving ICV ERT. We demonstrated a substantial and continuing reduction in the proportion of abnormal cells over the course of treatment, whereas symptomatic scores revealed little or no change over time. Here, we proposed the use of the proportion of cells with abnormal storage as a biomarker of response to therapy in CLN2. In the future, as more tissue-specific biomarkers are developed, the buffy coats may form part of a panel of biomarkers in order to give a more holistic view of a complex disease.

Role of Electroencephalogram (EEG) and Magnetic Resonance Imaging (MRI) Findings in Early Recognition and Diagnosis of Neuronal Ceroid Lipofuscinosis Type 2 Disease

Neuronal ceroid lipofuscinosis type 2 (CLN2) disease is a very rare neurodegenerative lysosomal storage disorder. Progression is rapid and irreversible, making early diagnosis crucial for timely treatment. A group of pediatric neurologists and neuroradiologists with expertise in CLN2 convened to discuss early electroencephalogram (EEG) and magnetic resonance imaging (MRI) findings in CLN2 diagnosis. Of 18 CLN2 cases, 16 (88.9%) had background slowing and 16 (88.9%) had epileptiform discharges on initial EEG. Seven of 17 (41.2%) patients who received intermittent low-frequency photic stimulation had a photoparoxysmal response. Initial MRIs showed subtle cerebellar (n = 14, 77.8%) or cerebral (n = 9, 50.0%) atrophy, white matter abnormalities (n = 11, 61.1%), and basal ganglia T2 hypointensity (n = 6, 33.3%), which became more apparent on follow-up MRI. The recognition of even subtle cerebellar atrophy and white matter signal changes in children aged 2-5 years who present with language delay, new-onset seizures, and an EEG with epileptiform discharges and background slowing should prompt investigation for CLN2. Because these early signs are not unique to CLN2, genetic testing is essential early in the diagnostic journey.

Provoked seizures at the onset of progressive disease contribute to diagnosis delay - A tertiary center experience in a cohort of 22 children with CLN2

PURPOSE

The evaluation of epilepsy features and factors with impact to diagnosis delay in children with CLN2.

METHOD

The study included children with CLN2 treated from 2000 to 2020. Diagnosis was confirmed by: TPP1 deficiency and/or TPP1 gene mutation or pathognomonic electron microscopy findings. The seizure features were evaluated: the age of onset, provocation, semiology and EEG. The disease severity was assessed by CLN2 Clinical Rating Scale (CLN2-CRS). Statistical analysis included T test, chi-square test, Wilcoxon-Mann-Whitney test, using SPSS statistics 25.

RESULT

The study included 22 children with CLN2. Seizures were experienced by all cases at the early stage of disease, preceded by language delay in 18, and behavior problems in 14 pts. The first seizure was provoked in 9 children at mean age of 33.8 ± 4.6 months, and unprovoked in 13 at mean age of 34.6 ± 2.7 months. In patients with provoked first seizure, the average period from the first seizure to diagnosis was longer (35.1 months), with lower CLN2-CRS, then in those with unprovoked (23.8 months) first seizures (p < 0.008). Initial seizures were generalized tonic-clonic (Pampiglione and Harden, 1973 Feb) [8], atonic (Pampiglione and Harden, 1973 Feb) [8], and focal (Beltrán et al., 2018 Aug) [4], with recurrence within two months. With progression, the patients experienced multiple seizure types, and 1/3 suffered status epilepticus.

CONCLUSIONS

Provoked seizures at the onset of CLN2 have impact to diagnosis delay. The red flags are: preceding language delay and behavior problems, later FS onset comparing to the typical age, atonic, focal and long-lasting seizure, and recurrence of seizures within two months.

New Indications for Hematopoietic Stem Cell Gene Therapy in Lysosomal Storage Disorders

Lysosomal storage disorders (LSDs) are a heterogenous group of disorders due to genetically determined deficits of lysosomal enzymes. The specific molecular mechanism and disease phenotype depends on the type of storage material. Several disorders affect the brain resulting in severe clinical manifestations that substantially impact the expectancy and quality of life. Current treatment modalities for LSDs include enzyme replacement therapy (ERT) and hematopoietic cell transplantation (HCT) from allogeneic healthy donors, but are available for a limited number of disorders and lack efficacy on several clinical manifestations. Hematopoietic stem cell gene therapy (HSC GT) based on integrating lentiviral vectors resulted in robust clinical benefit when administered to patients affected by Metachromatic Leukodystrophy, for whom it is now available as a registered medicinal product. More recently, HSC GT has also shown promising results in Hurler syndrome patients. Here, we discuss possible novel HSC GT indications that are currently under development. If these novel drugs will prove effective, they might represent a new standard of care for these disorders, but several challenges will need to be addresses, including defining and possibly expanding the patient population for whom HSC GT could be efficacious.

Value of genetic testing for pediatric epilepsy: Driving earlier diagnosis of CLN2 Batten disease

This study assessed the effectiveness of genetic testing in shortening the time to diagnosis of late infantile neuronal ceroid lipofuscinosis type 2 (CLN2) disease. Individuals who received epilepsy gene panel testing through Behind the Seizure^®, a sponsored genetic testing program (Cohort A), were compared to children outside of the sponsored testing program during the same period (Cohort B). Two cohorts were analyzed: children aged ≥24 to ≤60 months with unprovoked seizure onset at ≥24 months between December 2016 and January 2020 (Cohort 1) and children aged 0 to ≤60 months at time of testing with unprovoked seizure onset at any age between February 2019 and January 2020 (Cohort 2). The diagnostic yield in Cohort 1A (n = 1814) was 8.4% (n = 153). The TPP1 diagnostic yield within Cohort 1A was 2.9‐fold higher compared to Cohort 1B (1.0%, n = 18/1814 vs. .35%, n = 8/2303; p = .0157). The average time from first symptom to CLN2 disease diagnosis was significantly shorter than previously reported (9.8 vs. 22.7 months, p < .001). These findings indicate that facilitated access to early epilepsy gene panel testing helps to increase diagnostic yield for CLN2 disease and shortens the time to diagnosis, enabling earlier intervention.

Neuronal Ceroid Lipofuscinosis: The Multifaceted Approach to the Clinical Issues, an Overview

The main aim of this review is to summarize the current state-of-art in the field of childhood Neuronal Ceroid Lipofuscinosis (NCL), a group of rare neurodegenerative disorders. These are genetic diseases associated with the formation of toxic endo-lysosomal storage. Following a brief historical review of the evolution of NCL definition, a clinically-oriented approach is used describing how the early symptoms and signs affecting motor, visual, cognitive domains, and including seizures, may lead clinicians to a rapid molecular diagnosis, avoiding the long diagnostic odyssey commonly observed. We go on to focus on recent advances in NCL research and summarize contributions to knowledge of the pathogenic mechanisms underlying NCL. We describe the large variety of experimental models which have aided this research, as well as the most recent technological developments which have shed light on the main mechanisms involved in the cellular pathology, such as apoptosis and autophagy. The search for innovative therapies is described. Translation of experimental data into therapeutic approaches is being established for several of the NCLs, and one drug is now commercially available. Lastly, we show the importance of palliative care and symptomatic treatments which are still the main therapeutic interventions.