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Mucopolysaccharidosis type IIIB: a current review and exploration of the AAV therapy landscape.

ABSTRACT: Mucopolysaccharidoses type IIIB is a rare genetic disorder caused by mutations in the gene that encodes for N-acetyl-alpha-glucosaminidase. This results in the aggregation of heparan sulfate polysaccharides within cell lysosomes that leads to progressive and severe debilitating neurological dysfunction. Current treatment options are expensive, limited, and presently there are no approved cures for mucopolysaccharidoses type IIIB. Adeno-associated virus gene therapy has significantly advanced the field forward, allowing researchers to successfully design, enhance, and improve potential cures. Our group recently published an effective treatment using a codon-optimized triple mutant adeno-associated virus 8 vector that restores N-acetyl-alpha-glucosaminidase levels, auditory function, and lifespan in the murine model for mucopolysaccharidoses type IIIB to that seen in healthy mice. Here, we review the current state of the field in relation to the capsid landscape, adeno-associated virus gene therapy and its successes and challenges in the clinic, and how novel adeno-associated virus capsid designs have evolved research in the mucopolysaccharidoses type IIIB field.

SUBMITTER: Rouse CJ

PROVIDER: S-EPMC10503619 | biostudies-literature | 2024 Feb

REPOSITORIES: biostudies-literature

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Mucopolysaccharidosis type IIIB: a current review and exploration of the AAV therapy landscape.

Rouse Courtney J CJ Jensen Victoria N VN Heldermon Coy D CD

Neural regeneration research 20240201 2

Mucopolysaccharidoses type IIIB is a rare genetic disorder caused by mutations in the gene that encodes for N-acetyl-alpha-glucosaminidase. This results in the aggregation of heparan sulfate polysaccharides within cell lysosomes that leads to progressive and severe debilitating neurological dysfunction. Current treatment options are expensive, limited, and presently there are no approved cures for mucopolysaccharidoses type IIIB. Adeno-associated virus gene therapy has significantly advanced the ...[more]

PMID: 37488890

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Project description:ObjectivesOur goal was to describe the neurobehavioral phenotype in mucopolysaccharidosis Type IIIB (MPS IIIB). Parents report that behavioral abnormalities are a major problem in MPS III posing serious challenges to parenting and quality-of-life for both patient and parent. Our previous research on MPS IIIA identified autistic symptoms, and a Klüver-Bucy-type syndrome as indicated by reduced startle and loss of fear associated with amygdala atrophy. We hypothesized that MPS IIIB would manifest similar attributes when assessed with the same neurobehavioral protocol.MethodsTen patients with MPS IIIB were compared with 9 MPS IIIA patients, all older than 6. 8 younger children with Hurler syndrome (1H) were chosen as a comparison group for the Risk Room procedure; MPS IH does not directly affect social/emotional function and these younger children were closer to the developmental level of the MPS IIIB group. To examine disease severity, cognitive ability was assessed. Four evaluations were used: the Risk Room procedure (to measure social-emotional characteristics, especially fear and startle responses), the Autism Diagnostic Observation Schedule (ADOS), the Sanfilippo Behavior Rating Scale (SBRS), and amygdala brain volumes calculated from manually-traced MRI images.ResultsThe two groups are equivalent in severity and show severe cognitive impairment. On the ADOS, the MPS IIIB patients exhibited the same autistic features as IIIA. The IIIB means differed from MPS IH means on most measures. However, the IIIB group did not approach the Risk Room stranger, like the MPS IH group who kept their distance, but unlike the IIIA group who showed no fear of the stranger. On the SBRS, the MPS IIIB patients were described as more inattentive and more fearful, especially of new people than the MPS IIIA. Onsets of some disease characteristics appeared more closely spaced and slightly earlier in MPS IIIB than IIIA.ConclusionsOn most behavioral measures, MPS IIIB patients did not differ substantially from MPS IIIA patients over age six, demonstrating autistic features and a Klüver Bucy-like syndrome including lack of fear and poor attention. Delay in onset of behavioral symptoms was associated with later diagnosis in two patients. Lack of fear, poor attention, and autistic-like symptomatology are as characteristic of MPS IIIB as they are of MPS IIIA. A possible difference is that the some behavioral abnormalities develop more quickly in MPS IIIB, If this is so, these patients may become at risk for harm and present a challenge for parenting even earlier than do those with MPS IIIA. .In future clinical trials of new treatments, especially with respect to quality of life and patient management, improvement of these behaviors will be an essential goal. Because very young patients were not studied, prospective natural history documentation of the early development of abnormal behaviors in MPS IIIB is needed.

Project description:Mucopolysaccharidosis type IIIB (MPS IIIB; Sanfilippo syndrome B; OMIM #252920) is a lethal, pediatric, neuropathic, autosomal recessive, and lysosomal storage disease with no approved therapy. Patients are deficient in the activity of N-acetyl-alpha-glucosaminidase (NAGLU; EC 3.2.150), necessary for normal lysosomal degradation of the glycosaminoglycan heparan sulfate (HS). Tralesinidase alfa (TA), a fusion protein comprised of recombinant human NAGLU and a modified human insulin-like growth factor 2, is in development as an enzyme replacement therapy that is administered via intracerebroventricular (ICV) infusion, thus circumventing the blood brain barrier. Previous studies have confirmed ICV infusion results in widespread distribution of TA throughout the brains of mice and nonhuman primates. We assessed the long-term tolerability, pharmacology, and clinical efficacy of TA in a canine model of MPS IIIB over a 20-month study. Long-term administration of TA was well tolerated as compared with administration of vehicle. TA was widely distributed across brain regions, which was confirmed in a follow-up 8-week pharmacokinetic/pharmacodynamic study. MPS IIIB dogs treated for up to 20 months had near-normal levels of HS and nonreducing ends of HS in cerebrospinal fluid and central nervous system (CNS) tissues. TA-treated MPS IIIB dogs performed better on cognitive tests and had improved CNS pathology and decreased cerebellar volume loss relative to vehicle-treated MPS IIIB dogs. These findings demonstrate the ability of TA to prevent or limit the biochemical, pathologic, and cognitive manifestations of canine MPS IIIB disease, thus providing support of its potential long-term tolerability and efficacy in MPS IIIB subjects. SIGNIFICANCE STATEMENT: This work illustrates the efficacy and tolerability of tralesinidase alfa as a potential therapeutic for patients with mucopolysaccharidosis type IIIB (MPS IIIB) by documenting that administration to the central nervous system of MPS IIIB dogs prevents the accumulation of disease-associated glycosaminoglycans in lysosomes, hepatomegaly, cerebellar atrophy, and cognitive decline.

Project description:Mucopolysaccharidosis type IIIB syndrome (Sanfilippo disease) is a rare autosomic recessif disorder caused by mutations in the α-N-acetylglucosaminidase (NAGLU) gene coding for a lysosomal enzyme, leading to neurodegeneration and progressive deterioration of cognitive abilities in affected children. To supply the missing enzyme, several recent human gene therapy trials relied on the deposit of adeno-associated virus (AAV) vectors directly into the brain. We reported safety and efficacy of an intracerebral therapy in a phase 1/2 clinical trial (https://clinicaltrials.gov/ct2/show/NCT03300453), with a recombinant AAV serotype 2/5 (rAAV2/5) coding human NAGLU in four children with MPS IIIB syndrome receiving immunosuppression. It was reported that AAV-mediated gene therapies might elicit a strong host immune response resulting in decreased transgene expression. To address this issue, we performed a comprehensive analysis of cellular immunity and cytokine patterns generated against the therapeutic enzyme in the four treated children over 5.5 years of follow-up. We report the emergence of memory and polyfunctional CD4+ and CD8+ T lymphocytes sensitized to the transgene soon after the start of therapy, and appearing in peripheral blood in waves throughout the follow-up. However, this response had no apparent impact on CNS transgene expression, which remained stable 66 months after surgery, possibly a consequence of the long-term immunosuppressive treatment. We also report that gene therapy did not trigger neuroinflammation, evaluated through the expression of cytokines and chemokines in patients' CSF. Milder disease progression in the youngest patient was found associated with low level and less differentiated circulating NAGLU-specific T cells, together with the lack of proinflammatory cytokines in the CSF. Findings in this study support a systematic and comprehensive immunomonitoring approach for understanding the impact immune reactions might have on treatment safety and efficacy of gene therapies.

Project description:Mucopolysaccharide diseases (MPS) are caused by deficiency of glycosaminoglycan (GAG) degrading enzymes, leading to GAG accumulation. Neurodegenerative MPS diseases exhibit cognitive decline, behavioural problems and shortened lifespan. We have characterised neuropathological changes in mouse models of MPSI, IIIA and IIIB to provide a better understanding of these events.Wild-type (WT), MPSI, IIIA and IIIB mouse brains were analysed at 4 and 9 months of age. Quantitative immunohistochemistry showed significantly increased lysosomal compartment, GM2 ganglioside storage, neuroinflammation, decreased and mislocalised synaptic vesicle associated membrane protein, (VAMP2), and decreased post-synaptic protein, Homer-1, in layers II/III-VI of the primary motor, somatosensory and parietal cortex. Total heparan sulphate (HS), was significantly elevated, and abnormally N-, 6-O and 2-O sulphated compared to WT, potentially altering HS-dependent cellular functions. Neuroinflammation was confirmed by significantly increased MCP-1, MIP-1α, IL-1α, using cytometric bead arrays. An overall genotype effect was seen in all parameters tested except for synaptophysin staining, neuronal cell number and cortical thickness which were not significantly different from WT. MPSIIIA and IIIB showed significantly more pronounced pathology than MPSI in lysosomal storage, astrocytosis, microgliosis and the percentage of 2-O sulphation of HS. We also observed significant time progression of all genotypes from 4-9 months in lysosomal storage, astrocytosis, microgliosis and synaptic disorganisation but not GM2 gangliosidosis. Individual genotype*time differences were disparate, with significant progression from 4 to 9 months only seen for MPSIIIB with lysosomal storage, MPSI with astrocytocis and MPSIIIA with microgliosis as well as neuronal loss. Transmission electron microscopy of MPS brains revealed dystrophic axons, axonal storage, and extensive lipid and lysosomal storage. These data lend novel insight to MPS neuropathology, suggesting that MPSIIIA and IIIB have more pronounced neuropathology than MPSI, yet all are still progressive, at least in some aspects of neuropathology, from 4-9 months.

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Mucopolysaccharidosis type IIIB: a current review and exploration of the AAV therapy landscape.

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Mucopolysaccharidosis type IIIB: a current review and exploration of the AAV therapy landscape.

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