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.

Haploidentical haematopoietic stem cell transplantation combined with post-transplant cyclophosphamide in neuronal ceroid lipofuscinosis: Experience in eight patients.

BACKGROUND: Neuronal ceroid lipofuscinoses (NCLs) are rare lysosomal storage disorders characterized by progressive mental retardation and motor developmental regression and myoclonic seizures. Hematopoietic stem cell transplantation (HSCT) has been suggested to be used in the treatment of lysosomal disorders and brain damage caused by a deficiency of soluble lysosomal enzymes. There are no previous reports on treating NCLs with HSCT in China. MATERIAL AND METHOD: NCL pediatric patients who underwent allo-HSCT at Affiliated Children's Hospital of Capital Institute of Pediatrics were involved. A combination of medical histories, clinical features, and genetic analyses was used for the diagnosis of all patients. The written consent form for allo-HSCT was attained from the patient's guardian, which was then reviewed and approved by the ethics committee before the procedure. RESULTS: From January 2018 to May 2019, the haplo-HSCT followed by PT/Cy on eight NCL pediatric patients was performed. The median age was 4.5 years (ranging from 2.8 to 7 years). The donors were their haploidentical HLA-matched parents, as no identically matched donors were found. The median nucleated cell count was 25.37 (10-34.41)×108/kg, and the median CD34+ count was 13.7 (8.95-22)×106/kg. Neutrophil reconstitution occurred 12 days (11-14 days) after transplantation, and the median platelet reconstitution time was 12 days (9-14 days) after transplantation. All patients achieved full donor chimerism and did not develop Grade II-IV acute GvHD or chronic GvHD after transplantation. The median follow-up period was 2.2 (1.5-2.6) years. All patients are still alive at present and develop no severe transplantation-related complications. The mental motor disorders, myoclonic seizures, and vision loss of all patients continued to progress. However, the progression slowed at 12 months after transplantation. CONCLUSION: This study demonstrated that it is safe and efficacious to treat NCLs with haplo-HSCT. Transplantation should be performed at an early stage for the survival quality of pediatric patients.

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.

Economic analysis of cerliponase alfa for treatment of late-infantile neuronal ceroid lipofuscinosis type 2 (CLN2).

BACKGROUND: Cerliponase alfa is an orphan drug approved for the treatment of late-infantile neuronal ceroid lipofuscinosis type 2 (CLN2). AIM: Our goal was to assess the cost-effectiveness of cerliponase alfa in patients with CLN2 in the socioeconomic context of the Republic of Serbia in contrast to symptomatic therapy. METHOD: For this study, a forty-year horizon and the perspective of the Serbian Republic Health Insurance Fund were used. Quality-adjusted life years gained with cerliponase alfa and comparator, as well as direct treatment costs, were the study's key outcomes. The creation and simulation of a discrete-event simulation model served as the basis for the investigation. Monte Carlo microsimulation was performed on a sample of 1000 virtual patients. RESULTS: When compared to symptomatic therapy, cerliponase alfa treatment was not cost-effective and was linked to negative net monetary benefit regardless of when the illness signs started. CONCLUSION: Cerliponase alfa is not more economical than symptomatic therapy for the treatment of CLN2 when using typical pharmacoeconomic analysis. Cerliponase alfa has been shown to be effective but more has to be done to make it accessible to all CLN2 patients.

Activation of PPARα Exhibits Therapeutic Efficacy in a Mouse Model of Juvenile Neuronal Ceroid Lipofuscinosis.

Juvenile neuronal ceroid lipofuscinosis (JNCL) is a fatal inherited neurodegenerative disease of children that occurs because of defective function of the lysosomal membrane glycoprotein CLN3. JNCL features glial activation and accumulation of autofluorescent storage material containing subunit c of mitochondrial ATP synthase (SCMAS), ultimately resulting into neuronal loss. Until now, no effective therapy is available for JNCL. This study underlines the possible therapeutic importance of gemfibrozil, an activator of peroxisome proliferator-activated receptor α (PPARα) and a lipid-lowering drug approved by the Food and Drug Administration in an animal model of JNCL. Oral gemfibrozil treatment reduced microglial and astroglial activation, attenuated neuroinflammation, restored the level of transcription factor EB (TFEB; the master regulator of lysosomal biogenesis), and decreased the accumulation of storage material SCMAS in somatosensory barrel field (SBF) cortex of Cln3Δex7/8 (Cln3ΔJNCL) mice of both sexes. Accordingly, gemfibrozil treatment also improved locomotor activities of Cln3ΔJNCL mice. While investigating the mechanism, we found marked loss of PPARα in the SBF cortex of Cln3ΔJNCL mice, which increased after gemfibrozil treatment. Oral gemfibrozil also stimulated the recruitment of PPARα to the Tfeb gene promoter in vivo in the SBF cortex of Cln3ΔJNCL mice, indicating increased transcription of Tfeb in the CNS by gemfibrozil treatment via PPARα. Moreover, disease pathologies aggravated in Cln3ΔJNCL mice lacking PPARα (Cln3ΔJNCLΔPPARα) and gemfibrozil remained unable to decrease SCMAS accumulation, reduce glial activation, and improve locomotor performance of Cln3ΔJNCLΔPPARα mice. These results suggest that activation of PPARα may be beneficial for JNCL and that gemfibrozil may be repurposed for the treatment of this incurable disease.SIGNIFICANCE STATEMENT Despite intense investigations, no effective therapy is available for JNCL, an incurable inherited lysosomal storage disorder. Here, we delineate that oral administration of gemfibrozil, a lipid-lowering drug, decreases glial inflammation, normalizes and/or upregulates TFEB, and reduces accumulation of autofluorescent storage material in SBF cortex to improve locomotor activities in Cln3Δex7/8 (Cln3ΔJNCL) mice. Aggravation of disease pathology in Cln3ΔJNCL mice lacking PPARα (Cln3ΔJNCLΔPPARα) and inability of gemfibrozil to decrease SCMAS accumulation, reduce glial activation, and improve locomotor performance of Cln3ΔJNCLΔPPARα mice delineates an important role of PPARα in this process. These studies highlight a new property of gemfibrozil and indicate its possible therapeutic use in JNCL patients.

Ongoing retinal degeneration despite intraventricular enzyme replacement therapy with cerliponase alfa in late-infantile neuronal ceroid lipofuscinosis type 2 (CLN2 disease).

BACKGROUND/AIMS: Late-infantile neuronal ceroid lipofuscinosis type 2 (CLN2) is a neurodegenerative, blinding lysosomal storage disorder. The purpose of the current study was to characterise the progression of CLN2-associated retinal degeneration in patients under intraventricular enzyme replacement therapy (ERT) with cerliponase alfa. METHODS: We analysed visual function, retinal morphology and neuropaediatric data using preferential looking test (PLT), Weill Cornell Batten Scale (WCBS), optical coherence tomography (OCT) imaging and the Hamburg Motor-Language late-infantile neuronal ceroid lipofuscinosis (LINCL) Scale (M-L scale). RESULTS: Fifty-six eyes of 28 patients had baseline PLT, WCBS and OCT. 15 patients underwent serial examinations, resulting in a total of 132 OCT scans and WCBS results, 66 Hamburg M-L scores and 49 PLT results during a mean follow-up time of 18.2 months (range 5-40). A negative correlation (r=-0.69, p<0.001) was found between central retinal thickness (CRT) values and age at examination with a maximal annual decrease of 23 µm between 56 and 80 months of age. A significant correlation was observed between PLT results and the age at examination (r=0.46, p=0.001), the WCBS scores (r=0.62; p<0.001) and CRT values (r=-0.64; p<0.001). The M-L score correlated with the ocular measurements (CRT: r=0.58, p<0.001; WCBS r=-0.64, p<0.001; PLT score: r=-0.57, p<0.001). CONCLUSION: Despite intraventricular ERT, retinal degeneration progressed in patients with CLN2 and was particularly pronounced between 56 and 80 months of age. Retina-directed therapies should therefore be initiated before or as early as possible during the phase of rapid retinal degeneration. PLT and WCBS were identified as valuable outcome measures to monitor disease progression. TRIAL REGISTRATION NUMBER: NCT04613089.

A Caenorhabditis elegans model of autosomal dominant adult-onset neuronal ceroid lipofuscinosis identifies ethosuximide as a potential therapeutic.

Autosomal dominant adult-onset neuronal ceroid lipofuscinosis (ANCL) is a rare neurodegenerative disorder characterized by progressive dementia and premature death. Four ANCL-causing mutations have been identified, all mapping to the DNAJC5 gene that encodes cysteine string protein α (CSPα). Here, using Caenorhabditis elegans, we describe an animal model of ANCL in which disease-causing mutations are introduced into their endogenous chromosomal locus, thereby mirroring the human genetic disorder. This was achieved through CRISPR/Cas9-mediated gene editing of dnj-14, the C. elegans ortholog of DNAJC5. The resultant homozygous ANCL mutant worms exhibited reduced lifespans and severely impaired chemotaxis, similar to isogenic dnj-14 null mutants. Importantly, these phenotypes were also seen in balanced heterozygotes carrying one wild-type and one ANCL mutant dnj-14 allele, mimicking the heterozygosity of ANCL patients. We observed a more severe chemotaxis phenotype in heterozygous ANCL mutant worms compared with haploinsufficient worms lacking one copy of CSP, consistent with a dominant-negative mechanism of action. Additionally, we provide evidence of CSP haploinsufficiency in longevity, as heterozygous null mutants exhibited significantly shorter lifespan than wild-type controls. The chemotaxis phenotype of dnj-14 null mutants was fully rescued by transgenic human CSPα, confirming the translational relevance of the worm model. Finally, a focused compound screen revealed that the anti-epileptic drug ethosuximide could restore chemotaxis in dnj-14 ANCL mutants to wild-type levels. This suggests that ethosuximide may have therapeutic potential for ANCL and demonstrates the utility of this C. elegans model for future larger-scale drug screening.

Cross-species efficacy of enzyme replacement therapy for CLN1 disease in mice and sheep.

CLN1 disease, also called infantile neuronal ceroid lipofuscinosis (NCL) or infantile Batten disease, is a fatal neurodegenerative lysosomal storage disorder resulting from mutations in the CLN1 gene encoding the soluble lysosomal enzyme palmitoyl-protein thioesterase 1 (PPT1). Therapies for CLN1 disease have proven challenging because of the aggressive disease course and the need to treat widespread areas of the brain and spinal cord. Indeed, gene therapy has proven less effective for CLN1 disease than for other similar lysosomal enzyme deficiencies. We therefore tested the efficacy of enzyme replacement therapy (ERT) by administering monthly infusions of recombinant human PPT1 (rhPPT1) to PPT1-deficient mice (Cln1-/-) and CLN1R151X sheep to assess how to potentially scale up for translation. In Cln1-/- mice, intracerebrovascular (i.c.v.) rhPPT1 delivery was the most effective route of administration, resulting in therapeutically relevant CNS levels of PPT1 activity. rhPPT1-treated mice had improved motor function, reduced disease-associated pathology, and diminished neuronal loss. In CLN1R151X sheep, i.c.v. infusions resulted in widespread rhPPT1 distribution and positive treatment effects measured by quantitative structural MRI and neuropathology. This study demonstrates the feasibility and therapeutic efficacy of i.c.v. rhPPT1 ERT. These findings represent a key step toward clinical testing of ERT in children with CLN1 disease and highlight the importance of a cross-species approach to developing a successful treatment strategy.

Therapeutic Management of COVID-19 in a Pediatric Patient with Neurodegenerative CLN2 Disease and ICV-Enzyme Replacement Therapy: A Case Report.

The 12 years old male patient presented here suffers from neuronal ceroid lipofuscinoses 2 (CLN2) (MIM# 204500) and receives intracerebroventricular enzyme replacement therapy (ICV-ERT) every 14 days. After the emergence of the coronavirus disease 2019 (COVID-19) pandemic, routine care of children and adolescents with rare chronic diseases has become challenging. Although, in general, children do not develop severe COVID-19, when severe acute respiratory syndrome coronavirus 2 infection was detected by polymerase chain reaction-screening examination in our CLN2 patient before hospital admission for ICV-ERT, he was regarded to be at risk. Upon diagnosis, the patient developed respiratory deterioration symptoms and was admitted to our pediatric intensive care unit to receive oxygen, remdesivir, and steroids. As far as we know, this is the first CLN2 patient receiving intraventricular enzyme therapy with COVID-19 who required intensive care treatment and specific therapy.

Alfacerliponase para tratamento da lipofuscinose ceroide neuronal tipo 2 (CLN2) / Cerliponase alfa for the treatment of lipofuscinosis neuronal ceroid type 2 (CLN2)

INTRODUÇÃO: A CLN2 é uma doença ultrarrara de extrema gravidade e que leva à mortalidade precoce. Na sua forma clássica, afeta crianças entre 2 e 4 anos de idade, com evolução degenerativa irreversível que resulta em morte entre os 10 anos e início da adolescência. É causada por mutações genéticas que resultam na deficiência da enzima tripeptidilpeptidase 1 (TPP1). Os principais sintomas são neurológicos: o paciente apresenta inicialmente crises epiléticas e atraso na fala e, com evolução da doença, surgem deficiências motoras, piora das crises epilépticas, perda da visão e da capacidade de comunicação, até evolução para óbito. De acordo com o Serviço de Genética Médica do Hospital de Clínicas de Porto Alegre, que realiza cerca de 90-95% dos diagnósticos de CLN2 no país, foram diagnosticados desde 2006 25 casos de CLN2, com uma média atual de 5 novos casos por ano. Contudo, parte dos afetados ainda não é identificada devido à raridade da CLN2. Atualmente não há tratamento específico para CLN2 no SUS, sendo o cuidado de suporte em saúde ofertado em caráter paliativo. Em 2018, alfacerliponase (Brineura®) teve registro aprovado pela Anvisa, sendo atualmente o único tratamento disponível para CLN2 no mundo. Considerando o exposto, o presente relatório tem por objetivo avaliar o pedido de incorporação de alfacerliponase como tratamento para CLN2 no SUS. TECNOLOGIA: Alfacerliponase (Brineura®). PERGUNTA: Alfacerliponase é eficaz, segura, custo-efetiva e viável economicamente no tratamento de CLN2 na perspectiva do SUS? EVIDÊNCIAS CLÍNICAS

Binding of hydroxychloroquine and chloroquine dimers to palmitoyl-protein thioesterase 1 (PPT1) and its glycosylated forms: a computational approach.

The lysosomal enzyme palmitoyl-protein thioesterase 1 (PPT1) removes thioester-linked fatty acid groups from membrane-bound proteins to facilitate their proteolysis. A lack of PPT1 (due to gene mutations) causes the progressive death of cortical neurons and is responsible for infantile neural ceroid lipofuscinosis (INCL), a severe neurodegenerative disorder in children. Conversely, PPT1 is often over-expressed in cancer, and considered as a valid target to control tumor growth. Potent and selective inhibitors of PPT1 have been designed, in particular 4-amino-7-chloro-quinoline derivatives such as hydroxychloroquine (HCQ) and the dimeric analogues Lys05 and DC661. We have modeled the interaction of these three compounds with the enzyme, taking advantage of the PPT1 crystallographic structure. The molecules can fit into the palmitate site of the protein, with the dimeric compounds forming more stable complexes than the monomer. But the molecular modeling suggests that the most favorable binding sites are located outside the active site. Two sites centered on residues Met112 and Gln144 were identified, offering suitable cavities for drug binding. According to the calculated empirical energies of interaction (ΔE), the dimer DC661 forms the most stable complex at site Met112 of palmitate-bound PPT1. N-glycosylated forms of PPT1 were elaborated. Paucimannosidic glycans (M2FA and M3F) and a bulkier tetra-antennary complex glycan were introduced at asparagine residues N197, N212 and N232. These N-glycans do not impede drug binding, thus suggesting that all glycoforms of PPT1 can be targeted with these compounds.Communicated by Ramaswamy H. Sarma.

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.

Repurposing of tamoxifen ameliorates CLN3 and CLN7 disease phenotype.

Batten diseases (BDs) are a group of lysosomal storage disorders characterized by seizure, visual loss, and cognitive and motor deterioration. We discovered increased levels of globotriaosylceramide (Gb3) in cellular and murine models of CLN3 and CLN7 diseases and used fluorescent-conjugated bacterial toxins to label Gb3 to develop a cell-based high content imaging (HCI) screening assay for the repurposing of FDA-approved compounds able to reduce this accumulation within BD cells. We found that tamoxifen reduced the lysosomal accumulation of Gb3 in CLN3 and CLN7 cell models, including neuronal progenitor cells (NPCs) from CLN7 patient-derived induced pluripotent stem cells (iPSC). Here, tamoxifen exerts its action through a mechanism that involves activation of the transcription factor EB (TFEB), a master gene of lysosomal function and autophagy. In vivo administration of tamoxifen to the CLN7Δex2 mouse model reduced the accumulation of Gb3 and SCMAS, decreased neuroinflammation, and improved motor coordination. These data strongly suggest that tamoxifen may be a suitable drug to treat some types of Batten disease.

Dose selection for intracerebroventricular cerliponase alfa in children with CLN2 disease, translation from animal to human in a rare genetic disease.

Neuronal ceroid lipofuscinosis type 2 (CLN2 disease) is an ultra-rare pediatric neurodegenerative disorder characterized by deficiency of the lysosomal enzyme tripeptidyl peptidase-1 (TPP1). In the absence of adequate TPP1, lysosomal storage material accumulation occurs in the central nervous system (CNS) accompanied by neurodegeneration and neurological decline that culminates in childhood death. Cerliponase alfa is a recombinant human TPP1 enzyme replacement therapy administered via intracerebroventricular infusion and approved for the treatment of CLN2 disease. Here, we describe two allometric methods, calculated by scaling brain mass across species, that informed the human dose selection and exposure prediction of cerliponase alfa from preclinical studies in monkeys and a dog model of CLN2 disease: (1) scaling of dose using a human-equivalent dose factor; and (2) scaling of compartmental pharmacokinetic (PK) model parameters. Source PK data were obtained from cerebrospinal fluid (CSF) samples from dogs and monkeys, and the human exposure predictions were confirmed with CSF data from the first-in-human clinical study. Nonclinical and clinical data were analyzed using noncompartmental analysis and nonlinear mixed-effect modeling approaches. Both allometric methods produced CSF exposure predictions within twofold of the observed exposure parameters maximum plasma concentration (Cmax ) and area under the curve (AUC). Furthermore, cross-species qualification produced consistent and reasonable PK profile predictions, which supported the allometric scaling of model parameters. The challenges faced in orphan drug development place an increased importance on, and opportunity for, data translation from research and nonclinical development. Our approach to dose translation and human exposure prediction for cerliponase alfa may be applicable to other CNS administered therapies being developed.

Evolution of the retinal function by flash-ERG in one child suffering from neuronal ceroid lipofuscinosis CLN2 treated with cerliponase alpha: case report.

INTRODUCTION: Neuronal ceroid lipofuscinoses (CLN) are neurodegenerative disorders among the most frequent, inherited as an autosomal recessive trait. Affected patients can present with progressive decline in cognitive and motor functions, seizures, a shortened life span and visual deficiency. CLN2 is one of the rare CLN that benefits from treatment by cerliponase alpha an enzyme replacement therapy. Preliminary results on treated animal models have shown delayed neurological signs and prolonged life span. However, cerliponase alpha did not prevent vision loss or retinal degeneration in those animal models. Cerliponase alpha has currently been delivered to a few CLN2-affected patients. We report the case of one patient suffering from CLN2 treated with intracerebroventricular infusions of cerliponase alpha 300 mg every two weeks. Evolution of his retinal function was assessed by three successive flash-ERG and flash-VEP recordings throughout his treatment over a 4-year period. RESULTS: Before treatment at the age of 4 years 5 months, patient's retinas were normal (normal fundi and normal flash-ERG). After 29 infusions at the age of 6 years 10 months, a-wave combined response was absent, while cone and flicker responses were normal. After 80 infusions at the age of 8 years 9 months, a-wave cone response was absent with b-wave peak time increased, and no combined response. COMMENTS: Despite treatment, our patient's retinas showed a progressive abnormal and inhomogeneous function. Rods function was altered first, then the scotopic system and afterward, the cones. This result differs from those recorded in animal models. The relative preservation of cone functioning for a while could not be unequivocally attributed to enzyme replacement therapy as we lack comparison with the evolution of flash-ERGs recorded in untreated subjects.

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.

Development of the "Hamburg Best Practice Guidelines for ICV-Enzyme Replacement therapy (ERT) in CLN2 Disease" Based on 6 Years Treatment Experience in 48 Patients.

Intracerebroventricular enzyme replacement therapy (ICV-ERT) for CLN2 disease represents the first approved treatment for neuronal ceroid lipofuscinosis (NCL) diseases. It is the first treatment where a recombinant lysosomal enzyme, cerliponase alfa, is administered into the lateral cerebral ventricles to reach the central nervous system, the organ affected in CLN2 disease. If untreated, CLN2 children show first symptoms such as epilepsy and language developmental delay at 2-4 years followed by rapid loss of motor and language function, vision loss, and early death. Treatment with cerliponase alfa has shown to slow the rapid neurologic decline. However, the mode of administration by 4 hour-long intracerebroventricular infusions every 14 days represents a potentially greater risk of infection compared to intravenous enzyme replacement therapies. The Hamburg NCL Specialty Clinic was the first site worldwide to perform intracerebroventricular enzyme replacement therapy in children with CLN2 disease. In order to ensure maximum patient safety, we analysed data from our center from more than 3000 intracerebroventricular enzyme replacement therapies in 48 patients over 6 years with regard to the occurrence of device-related adverse events and device infections. Since starting intracerebroventricular enzyme replacement therapy, we have also developed and continuously improved the "Hamburg Best Practice Guidelines for ICV-Enzyme Replacement Therapy (ERT) in CLN2 Disease." Results from this study showed low rates for device-related adverse events and infections with 0.27% and 0.33%, respectively. Therefore, following our internal procedural guidelines has shown to improve standardization and patient safety of intracerebroventricular enzyme replacement therapy for CLN2 disease.

Managing CLN2 disease: a treatable neurodegenerative condition among other treatable early childhood epilepsies.

INTRODUCTION: Neuronal ceroid lipofuscinosis type 2 (CLN2 disease) is a rare pediatric neurodegenerative condition, which is usually fatal by mid-adolescence. Seizures are one of the most common early symptoms of CLN2 disease, but patients often experience language deficits, movement disorders, and behavioral problems. Diagnosis of CLN2 disease is challenging (particularly when differentiating between early-onset developmental, metabolic, or epileptic syndromes), and diagnostic delays often overlap with rapid disease progression. An enzyme replacement therapy (cerliponase alfa) is now available, adding CLN2 disease to the list of potentially treatable disorders requiring a prompt diagnosis. AREAS COVERED: Although advances in enzymatic activity testing and genetic testing have facilitated diagnoses of CLN2 disease, our review highlights the presenting symptoms that are vital in directing clinicians to perform appropriate tests or seek expert opinion. We also describe common diagnostic challenges and some potential misdiagnoses that may occur during differential diagnosis. EXPERT OPINION: An awareness of CLN2 disease as a potentially treatable disorder and increased understanding of the key presenting symptoms can support selection of appropriate tests and prompt diagnosis. The available enzyme replacement therapy heralds an even greater imperative for early diagnosis, and for clinicians to direct patients to appropriate diagnostic pathways.