Enzyme Replacement Therapy in CLN2-Associated Retinopathy.

Neuronal ceroid lipofuscinosis type 2 (CLN2) is a rapidly progressive neurodegenerative disorder leading to premature mortality. Ambulatory CLN2 patients typically receive standard of care treatment through biweekly intracerebroventricular (ICV) enzyme replacement therapy (ERT) involving recombinant human tripeptidyl peptidase 1, known as cerliponase alfa (Brineura®, Biomarin Pharmaceuticals). This study longitudinally assessed the impact of ICV cerliponase alfa ERT on gait, and postural control across a two-year span in two siblings diagnosed with atypical CLN2 disease. Both participants, ID01 (18 years and 8 months old at enrollment) and ID02 (13 years and 3 months old at enrollment), exhibited symptomatic characteristics which were studied longitudinally over three years. Their evaluations assessed postural sway variability, potential for slips and trips, gait metrics, sit-to-stand durations, scores from the sensory organization test (SOT), and gross motor function measure (GMFM) scores. Findings indicated a decline in postural complexity and stability in the medial-lateral (ML) axis, a reduction in toe clearance, and an augmented risk of stumbling for the participants. Over the two-year period of ERT, both siblings exhibited a progressive decline in walking velocity, characterized by reductions in step length and prolonged gait cycle time. The elder sibling demonstrated a notable increase in double support duration, indicative of heightened reliance on proprioceptive input to maintain stability during ambulation. Additionally, sit-to-stand times lengthened for siblings, further reflecting declines in motor function. Despite these challenges, SOT scores showed improvement after two years of ERT, suggesting some preservation of sensory integration. These findings in SOT scores indicate that cerliponase alfa treatment in patients with atypical CLN2 disease may confer benefits in postural stability, lower extremity strength, and ankle stiffness. However, declines in more complex motor functions, including sit-to-stand performance and postural complexity, persist, underscoring the progressive nature of the disease despite ongoing therapeutic intervention.

Background/aimsLate-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...

Intraventricular Enzyme Replacement Improves Disease Phenotypes in a Mouse Model of Late Infantile Neuronal Ceroid Lipofuscinosis

Enzyme replacement therapy (ERT) with cerliponase alfa (Brineura) has been shown to slow the progression of milestone deterioration in neuronal ceroid lipofuscinosis type 2 (CLN2), an inherited neurodegenerative lysosomal storage disorder. Cerliponase alfa must be administered intraventricularly every 2 weeks, necessitating the placement of ventricular reservoirs and requiring frequent access. Traditionally, positive cerebrospinal fluid (CSF) cultures obtained from implanted ventricular reservoirs are managed with device replacement and antibiotic treatment. The authors sought to establish which circumstances might allow for careful observation without device removal. In this study, the authors report their single-institution experience with the clinical outcomes of positive CSF cultures in 16 CLN2 patients with ventricular reservoirs over 6 years. The authors retrospectively reviewed a cohort of 16 patients with CLN2 disease who had ventricular reservoirs placed for ERT administration. At each ERT infusion, CSF was collected by sterile technique and cultured with both thioglycolate broth and agar plate. This CSF collection was standard practice as per the initial trial protocol for use of ERT in CLN2. Epidemiological and microbiological data, symptomatology, total antibiotic days, removal and replacement of the ventricular reservoir, hospital length of stay, and mortality were analyzed for each patient. In the authors' cohort, 11 of 16 patients (69%) had at least 1 positive CSF culture. Of the 11 patients with positive cultures, only 3 had their device removed and replaced due to a positive culture with concurrent antibiotic treatment at the authors' center, and 2 patients subsequently were treated with prophylactic antibiotic infusion. Of 1401 total CSF cultures, 64 (4.56%) were positive. The most common organism grown was Cutibacterium acnes, which typically only grew in broth culture (82%), suggesting low bacterial burden. The other 8 patients with positive cultures remained asymptomatic with no intervention required. At the authors' institution, we have found that in asymptomatic patients with frequently accessed ventricular reservoirs, positive CSF culture with low virulence skin flora was common. Rarely did positive cultures with common skin flora necessitate intervention. The authors' experience has shown that nonvirulent infection of ventricular reservoirs with low virulence skin flora can be monitored without intervention. This strategy reduces the risks of invasive surgery, prolonged antibiotic courses, and missed infusions.

Neuronal ceroid lipofuscinosis type 2 (CLN2) is an autosomal recessive lysosomal disease caused by decreased activity of the enzyme tripeptidyl peptidase 1 (TPP1) due to pathogenic variants in the TPP1 gene. Cerliponase alfa, a recombinant proenzyme form of TPP1, has shown efficacy in preventing motor and language function decline in early-stage CLN2. However, the safety and effects of this therapy in advanced-stage CLN2 are unclear. We herein report a case of intraventricular cerliponase alfa treatment for over a year in a patient with advanced-stage CLN2. The results suggest the safety and potential efficacy of treatment at an advanced stage of CLN2.

Bull's eye maculopathy and subfoveal deposition in two mucopolysaccharidosis type I patients on long-term enzyme replacement therapy

Neuronal ceroid lipofuscinosis type 2 (CLN2) is a rare neurodegenerative genetic disease that affects children in early life. Its classic form is rapidly progressive, leading to death within the first 10 years. The urge for earlier diagnosis increases with the availability of enzyme replacement therapy. A panel of nine Brazilian child neurologists combined their expertise in CLN2 with evidence from the medical literature to establish a consensus to manage this disease in Brazil. They voted 92 questions including diagnosis, clinical manifestations, and treatment of the disease, considering the access to healthcare in this country. Clinicians should suspect CLN2 disease in any child, from 2 to 4 years old, with language delay and epilepsy. Even though the classic form is the most prevalent, atypical cases with different phenotypes can be found. Electroencephalogram, magnetic resonance imaging, molecular and biochemical testing are the main tools to investigate and confirm the diagnosis. However, we have limited access to molecular testing in Brazil, and rely on the support from the pharmaceutical industry. The management of CLN2 should involve a multidisciplinary team and focus on the quality of life of patients and on family support. Enzyme replacement therapy with Cerliponase α is an innovative treatment approved in Brazil since 2018; it delays functional decline and provides quality of life. Given the difficulties for the diagnosis and treatment of rare diseases in our public health system, the early diagnosis of CLN2 needs improvement as enzyme replacement therapy is available and modifies the prognosis of patients.

Late-infantile neuronal ceroid lipofuscinosis (LINCL) and juvenile neuronal ceroid lipofuscinosis (JNCL) are inherited neurodegenerative diseases caused by mutations in the genes encoding lysosomal proteins tripeptidyl peptidase 1 (TPP1) and CLN3 protein, respectively. TPP1 is well-understood and, aided by animal models that accurately recapitulate the human disease, enzyme replacement therapy has been approved and other promising therapies are emerging. In contrast, there are no effective treatments for JNCL, partly because the function of the CLN3 protein remains unknown but also because animal models have attenuated disease and lack robust survival phenotypes. Mouse models for LINCL and JNCL, with mutations in Tpp1 and Cln3, respectively, have been thoroughly characterized but the phenotype of a double Cln3/Tpp1 mutant remains unknown. We created this double mutant and find that its phenotype is essentially indistinguishable from the single Tpp1-/- mutant in terms of survival and brain pathology. Analysis of brain proteomic changes in the single Tpp1-/- and double Cln3-/- ;Tpp1-/- mutants indicates largely overlapping sets of altered proteins and reinforces earlier studies that highlight GPNMB, LYZ2, and SERPINA3 as promising biomarker candidates in LINCL while several lysosomal proteins including SMPD1 and NPC1 appear to be altered in the Cln3-/- animals. An unexpected finding was that Tpp1 heterozygosity significantly decreased lifespan of the Cln3-/- mouse. The truncated survival of this mouse model makes it potentially useful in developing therapies for JNCL using survival as an endpoint. In addition, this model may also provide insights into CLN3 protein function and its potential functional interactions with TPP1.

The aim of this study was to examine the ophthalmological characteristics and genotypes of patients with congenital retinal pathologies, who display a bull's-eye maculopathy in the fundus, along with a negative scotopic electroretinogram. We analysed the results of five patients showing both a bull's-eye maculopathy, as well as a negative scotopic ERG evoked by a bright flash. Their median age was 39years (range 11-63years): three males and two females. All underwent a comprehensive examination with determination of distant visual acuity (ETDRS) and recording of the full-field ERG (scotopic and photopic). Fundus, OCT, and FAF images were obtained, the kinetic visual field was determined, and colour vision (D-15) was tested in most patients. Targeted gene panel sequencing was performed on peripheral blood. One patient carried a homozygous ABCA4 mutation and an additional heterozygous variant in CRX. Two of the five patients were shown to have a heterozygous mutation in the CRX gene, one of whom had an additional heterozygous ABCA4 mutation. Two patients had the common heterozygous mutation c.2413G>A;p.Arg838His in GUCY2D. In all of the patients, there was a reduction in the amplitude of the b-wave with a regular a-wave amplitude in the scotopic bright-flash ERG. The five patients with bull's-eye maculopathy along with a negative ERG had differing genotypes. Mutations were found in the CRX gene (2 patients), the ABCA4 gene (1 patient), and the GUCY2D gene (2 patients).

Molecular analysis in exons 1 and 2 of the tripeptidyl peptidase 1 (TPP1) gene on patients with neuronal ceroid lipofuscinosis type 2 (CLN2) in Indonesia

Bull's-Eye maculopathy secondary to herbal toxicity from uva ursi

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

Clinical data were retrospectively collected from 13 children with type 2 neuronal ceroid lipofuscinosis (CLN2) who underwent genetic testing for definitive diagnosis and were followed up at the Chinese PLA General Hospital from January 2018 to December 2023. The clinical features, disease progression, and prognosis were analyzed. The age at onset was [M(Q1, Q3)] 3.7 (3.2, 4.5) years, including 7 males and 6 females. The follow-up was conducted once every 3 months during the first 2 years after diagnosis, and once every 6 months starting from the 3rd year, with the last follow-up until December 2025. All patients presented with epilepsy as the initial manifestation, of whom 8 patients had myoclonic seizures. Psychomotor regression occurred in 10 patients shortly after seizure onset. Tripeptidyl peptidase 1 (TPP1) activity was below the normal reference range in all patients, and all harbored biallelic pathogenic or likely pathogenic variants in the TPP1 gene. Brain magnetic resonance imaging revealed cerebellar atrophy in all cases, and electroencephalography demonstrated generalized abnormalities in all patients. Disease progression exhibited relatively distinct stage-wise features. Within>1-2 years of onset, eleven patients developed ataxia and 10 experienced language regression. Within>2-3 years, ten patients had lost independent ambulation and 9 had lost language function. Within>3-5 years, all patients lost motor and language abilities, and 10 developed severe dysphagia. Five patients died during follow-up. In conclusion, CLN2 typically presents in early childhood with epilepsy as the predominant initial manifestation, followed by progressive neurofunctional decline and cerebellar atrophy. Markedly reduced TPP1 activity together with pathogenic TPP1 variants supports the diagnosis.

BackgroundLow expression of highly‐charged recombinant proteins remains a critical challenge in developing protein‐based therapeutics. It has been shown that inclusion of a polyanionic tract (PAT) may improve expression through inter‐ and intramolecular interactions. We previously developed a chimeric construct consisting of tripeptidyl‐peptidase 1 (TPP1), a glycine‐serine linker ([GS]5), a glycine‐aspartate PAT ([GD3]3), and a basic cell‐penetrating peptide K16ApoE as a potential therapeutic agent for late‐infantile neuronal ceroid lipofuscinosis. While TPP1‐(GS)5‐(GD3)3‐(GS)5‐K16ApoE was expressed efficiently, it was cleaved at the PAT. We therefore sought to design novel PATs that improve expression of the full‐length chimera.MethodsTPP1:K16ApoE chimeric proteins were synthesized to contain tri‐glutamate sequences instead of tri‐aspartate sequences in the original (GD3)3PAT. All seven possible combinations of substitutions were engineered: (GE3)3, (GE3)‐(GD3)2, (GD3)‐(GE3)‐(GD3), (GD3)2‐(GE3), (GE3)2‐(GD3), (GE3)‐(GD3)‐(GE3), or (GD3)‐(GE3)2. Chimeric proteins were expressed in Chinese hamster ovary (CHO) cells and media samples were assayed for TPP1 activity. Activity was normalized to a wild‐type (unmodified) TPP1 positive control expressed in CHO cells. The identity of each construct was verified using SDS‐PAGE and mass spectrometry. Welch’s ANOVA test was used to determine expressional differences between TPP1‐(GS)5‐K16ApoE and PAT‐modified chimeras and the resulting p‐values were adjusted for multiple comparisons using Dunnett’s T3 multiple comparison test.ResultsSeven constructs were synthesized, corresponding to each of the aforementioned tri‐glutamate‐substituted PATs, following the general format of TPP1‐(GS)5‐(PAT)‐(GS)5‐K16ApoE. All chimeras expressed successfully as full‐length constructs (Figure 1). No TPP1 activity was detected in the media of untransfected CHO cells. TPP1‐(GS)5‐K16ApoE was previously determined to express at 1.4±1.0% of unmodified TPP1. Of these chimeras with novel PATs, TPP1‐(GS)5‐(GE3)‐(GD3)2‐(GS)5‐K16ApoE [mean ± standard error: 7.3±1.7%, p=0.0040] and TPP1‐(GS)5‐(GE3)2‐(GD3)‐(GS)5‐K16ApoE [5.8±3.1%, p=0.0397] exhibited significantly increased expression relative to TPP1‐(GS)5‐K16ApoE at the 0.05 level of significance.ConclusionAlteration of the a priori (GD3)3 PAT sequence by varying the aspartate and glutamate content was sufficient to prevent cleavage of the resulting TPP1:K16ApoE chimeras. However, only the (GE3)‐(GD3)2 and (GE3)2‐(GD3) PATs yielded a 5‐fold and a 4‐fold, respectively, improvement in expression over the original TPP1‐(GS)5‐K16ApoE construct. Further investigation is required to understand the electrostatic and/or structural basis of these findings.

660. Quantitative Comparison of AAV Serotypes AAV2, AAV5, and AAVrh.10 Efficiency for CNS Gene Therapy Following Intracranial Gene Delivery