2026-07-08 | Personalized Drug Repurposing Screen Identifies Patient-Specific Therapeutic Candidates for Mucopolysaccharidosis Type IIIB
Background: Mucopolysaccharidosis type IIIB (MPSIIIB, Sanfilippo syndrome type B) is a rare lysosomal storage disease caused by deficiency of alpha-N-acetylglucosaminidase (NAGLU) enzyme, leading to progressive accumulation of heparan sulfate and severe neurological decline. MPSIIIB’s significant genetic heterogeneity presents a major barrier to developing broadly effective treatments and suggests a need for personalized therapeutic strategies. Methods: We established a personalized drug repurposing platform using high-content imaging with lysotracker dye as an indirect functional readout of lysosomal dysfunction to screen compounds that correct lysosomal defects in patient-derived fibroblasts. We screened 2807 compounds on cells from an MPSIIIB patient with a homozygous NAGLU p.Arg297Ter mutation. Hits that reduced lysosomal accumulation by at least 25% with minimal cytotoxicity were validated and subsequently tested for efficacy in fibroblasts from a second patient with a different, compound heterozygous NAGLU genotype. Results: The primary screen yielded 72 hits (2.6% hit rate), with 10 confirmed in dose–response assays. Notably, four clinically approved drugs—baclofen, dextrose, epalrestat and moxifloxacin—reduced lysosomal accumulation in the index patient’s cells. However, none of these four drugs were effective in the second patient’s cells, demonstrating a profound patient-specific effect. Only one non-clinical compound, 6-chlorothymol, showed a trend toward activity in both cell lines. Conclusions: Our study demonstrates a feasible framework for conducting rapid, N-of-1 drug repurposing screens for rare diseases. While we identified four promising candidates for the index patient, the lack of efficacy in a second patient cell line underscores that genetic heterogeneity may preclude a “one-size-fits-all” approach for MPSIIIB. These findings support the integration of individualized drug screening as a potential precision-medicine strategy, offering a potential path toward patient-specific therapies for rare diseases rather than traditional drug development.
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2026-06-09 | Three-Month Observational Data for the MPS IIIB Sentinel Subject Following AAV9 Mediated Gene Therapy
Abstract Background Mucopolysaccharidosis type IIIB (MPS IIIB) is a devastating neurodegenerative lysosomal storage disorder caused by alpha-N-acetylglucosaminidase (NAGLU) deficiency. There is currently no approved therapy. We report the 3-month outcomes of a novel intracerebroventricular (ICV) gene therapy in a child with MPS IIIB. Methods In an open-label, single-center, investigator-initiated trial (ChiCTR2600121466), a single dose of RDGT-101 (2.0E14vg of an AAV9 vector encoding human NAGLU ) was administered via ICV infusion. Primary outcomes were safety and tolerability. Secondary outcomes included serum NAGLU activity, urinary heparan sulfate (HS) excretion, and neurocognitive function. Exploratory analyses included hematological parameters. Results The patient achieved serum NAGLU activity (17.06 nmol/mL/hour) approaching that of healthy controls (17.75 ± 1.37 nmol/mL/hour) by Month 3, accompanied by a 58.4% reduction in urinary HS. Clinically, previously severe hand and toe contractures resolved, allowing for full extension. Neurocognitive improvements were observed, including clear articulation, logical conversation, and sustained eye contact. Hematological analyses revealed normalized red blood cell indices and improved iron utilization. No dose-limiting toxicities, serious adverse events, or clinically significant laboratory abnormalities were observed. Conclusions A single ICV infusion of RDGT-101 was safe and well-tolerated in this patient with MPS IIIB. Early biochemical correction was accompanied by marked improvements in somatic, neurocognitive, and hematological parameters. These findings support further investigation of ICV AAV9 gene therapy for MPS IIIB.
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2026-05-27 | Mapping Sanfilippo Syndrome: A Multisystem Clinicopathological Autopsy.
Background/Objectives: Mucopolysaccharidosis type III (MPS III, Sanfilippo syndrome) is an autosomal recessive lysosomal storage disorder caused by deficiencies in enzymes required for heparan sulfate degradation. While primarily recognized for its devastating neurodegenerative course, the systemic extent of glycosaminoglycan (GAG) accumulation remains under-characterized. This study aims to provide a detailed multisystemic pathological mapping of MPS III to challenge the traditional "brain-only" disease paradigm and highlight the clinical relevance of extracerebral involvement. Methods: We present a comprehensive clinicopathological analysis of a 15-year-old female patient with a history of profound neuropsychomotor delay, refractory epilepsy, and spastic tetraplegia. Following her death due to terminal bronchopneumonia during palliative care, a complete forensic and pathological autopsy was conducted. Tissue samples from all major organ systems were processed using routine Hematoxylin-Eosin (HE) staining, immunohistochemical staining for CD68, and specialized histochemical stains to identify intracellular storage products. Results: Macroscopic evaluation revealed significant diffuse cerebral atrophy, meningoencephalic edema, cardiac valvulopathy with compensatory myocardial remodeling, and hepatosplenomegaly. Furthermore, erosive gastrointestinal lesions and degenerative renal changes were identified. Histopathological examination confirmed widespread cytoplasmic vacuolization across diverse cell populations, including neurons, hepatocytes, renal tubular cells, and the reticuloendothelial system. These findings demonstrate that GAG deposition is a generalized process affecting nearly every parenchymal structure. Conclusions: Although neurological decline dominates the clinical phenotype, our findings underscore that MPS III is a true systemic storage disorder. Significant involvement of the cardiovascular and visceral systems contributes to the disease's complexity and mortality. This case reinforces the critical diagnostic value of a comprehensive autopsy in delineating the full morphological spectrum of Sanfilippo syndrome, providing essential insights for multidisciplinary management.
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2026-04-29 | Short-Term Oral Spermidine Supplementation Modifies Aspects of Neurodegenerative Disease in Flies and Mice With MPS III.
Mucopolysaccharidosis type III (MPS III) is a group of autosomal recessive neurodegenerative lysosomal storage disorders that causes progressive cognitive and physical impairment, predominantly in child/early adulthood. The median age of death is 17 years as there is no safe, effective treatment approved. Using faithful Drosophila and murine models of MPS III, we have characterised the MPS IIIA and MPS IIIC fly metabolome, explored the ability of oral spermidine supplementation to ameliorate clinical disease in the fly models and explored its mechanism of action in MPS IIIA mice. Spermidine is a polyamine naturally synthesised by the body. Its manufacture decreases with age. Supplementation has been reported to stimulate autophagy, reduce cell senescence and increase health/lifespan. The metabolomic evaluation confirmed that whole MPS IIIA and MPS IIIC flies exhibit a progressively deranged metabolome. Significantly up-regulated metabolites were those involved in nucleotide and purine metabolism. The most significantly down-regulated metabolites were those involved in ascorbate and aldarate metabolism. Further, spermidine levels decreased significantly in all fly genotypes with age. In short-term studies, food enriched with 5 mM spermidine improved overall fly activity and climbing ability. A 4-week study in pre-symptomatic MPS IIIA mice (3- or 6-mM spermidine, supplemented in drinking water) revealed no improvement in microgliosis or lysosomal compartment size; however, we observed a significant reduction in the astroglial response in the brain, which is believed to drive disease progression. Longer-term confirmatory studies in larger cohorts of MPS III animals are now warranted to determine whether spermidine supplementation is of benefit in preventing or slowing clinical disease in this and other childhood dementias.
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2026-02-27 | Evaluation of GlcNAc-Configured Glycomimetics as Pharmacological Chaperones of NAGLU for the Treatment of Mucopolysaccharidosis IIIB.
The interaction of a set of four N-acetyl-glucosamine (GlcNAc) glycomimetics with human N-acetyl-glucosaminidase (NAGLU), the genetically defective enzyme in patients suffering from mucopolysaccharidosis (MPS) IIIB, also known as Sanfilippo B syndrome, was investigated to identify potential pharmacological chaperones. Glycomimetic-NAGLU binding was initially studied by molecular docking simulations and a thermal shift assay. The effects of the glycomimetics on NAGLU activity enhancement were studied in fibroblast cells from seven MPS IIIB patients. A significant increase in NAGLU activity in four cell lines in the presence of glycomimetic MK 8719, a molecule tested in a Phase 1 study in healthy volunteers to treat Alzheimer's disease, was demonstrated. Furthermore, MK 8719 prevented the increase in glycosaminoglycan (GAG) levels in four MPS IIIB fibroblast cells, suggesting that this molecule may be worth investigating further as a pharmacological chaperone for MPS IIIB. These results represent an important contribution towards the development of a specific therapy for MPS IIIB.
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