A Cure for Sanfilippo Syndrome? A Summary of Current Therapeutic Approaches and their Promise

Tandem mass spectrometry-based assay for heparan-N-sulphatase in paediatric CSF: A potential pharmacodynamic biomarker for mucopolysaccharidosis type IIIA therapy

Mucopolysaccharidosis type IIIA is a lysosomal storage disorder caused by mutations in the gene coding for heparan-N-sulphatase, a crucial enzyme in the degradation of heparan sulfate. In mucopolysaccharidosis type IIIA, heparan sulfate accumulates in the lysosomes, predominantly affecting the central nervous system. It is the most common and most severe form of mucopolysaccharidosis type III, with onset typically before the age of ten years. There is an ongoing effort to develop therapies that aim at restoring enzyme function in the brain. This study introduces a novel tandem mass spectrometry method for assessing heparan-N-sulphatase activity in pediatric cerebrospinal fluid from healthy and disease individuals. Analysis of cerebrospinal fluid samples revealed marked differences in enzyme activity, with mucopolysaccharidosis type IIIA individuals exhibiting significantly reduced levels. This new method could serve as a valuable tool for evaluating the efficacy of future therapeutic interventions targeting sulphatase activity restoration in the brain.

Anakinra in Sanfilippo syndrome: a phase 1/2 trial

Sanfilippo syndrome is a fatal childhood neurodegenerative disorder involving neuroinflammation among multiple pathologies. We hypothesized that anakinra, a recombinant interleukin-1 receptor antagonist, could improve neurobehavioral and functional symptoms owing to its capacity to treat neuroinflammation. This phase 1/2 trial aimed to test the safety, tolerability and effects of anakinra on neurobehavioral, functional and quality-of-life outcomes in patients and their caregivers. The primary outcome was the percent of participants requiring a dose increase at week 8 or week 16. Secondary efficacy outcomes included a multi-domain responder index (MDRI). Twenty-three participants (6-26 years of age) were enrolled. Twenty continued treatment to week 8, and 15 (75%) required an increased dose at week 8 or week 16. There was an improvement in at least one domain in the MDRI in 18 of 21 (86%) at week 8 and in 15 of 16 (94%) at week 36. Seven participants withdrew (intolerability of daily injections and lost to follow-up) before week 36. Adverse events occurred in 22 of 23 (96%) participants, most commonly mild injection site reactions. No serious adverse events were related to anakinra. In conclusion, anakinra was safe and associated with improved neurobehavioral and functional outcomes, supporting continued investigation of anakinra in Sanfilippo syndrome and other mucopolysaccharidoses. ClinicalTrials.gov identifier: NCT04018755 .

Current Concepts in the Management of Sanfilippo Syndrome (MPS III): A Narrative Review

Sanfilippo syndrome is a childhood-onset (1-4 years) autosomal recessive lysosomal storage disease that presents as a neurodegenerative disease by targeting the brain and spinal cord. It is also known as mucopolysaccharidosis III. Mucopolysaccharidosis III is divided into four subtypes (A, B, C, or D). It can cause delayed speech, behavior problems, and features of autism spectrum disorder. Sanfilippo syndrome is of a higher prevalence within consanguineous families that carry its gene alteration. If both parents have a nonfunctional copy of a gene linked to this condition, their children will have a 25% (1 in 4) chance of developing the disease. In Saudi Arabia, the incidence rate is estimated at 2 per 100,000 live births. Recent research focused on promising treatment approaches, such as gene therapy, modified enzyme replacement therapy, and stem cells. These approaches work by exogenous administration of the proper version of the mutant enzyme (enzyme replacement therapy), cleaning the defective enzyme in individuals with glycolipid storage disorders (substrate reduction therapy), or using a pharmacological chaperone to target improperly folded proteins. However, there is currently no approved curative medication for Sanfilippo syndrome that can effectively halt or reverse the disorder.

Ability change across multiple domains in mucopolysaccharidosis (Sanfilippo syndrome) type IIIA

The objective of this paper is 1) to expand the scope of the domains previously published in a natural history study of Mucopolysaccharidosis IIIA (Sanfilippo syndrome type A) (MPS IIIA) and 2) to present evidence regarding the capacity of a new metric, Growth Scale Values (GSVs), in comparison with traditional metrics, to show changes in skills as assessed by the Bayley Scales of Infant Development -III (BSID-III) and the Vineland Adaptive Behavior Scales, Second Edition (VABS-II). We re-analyzed a cohort of 25 children, 20 with rapid progressing disease and 5 with slow progression, who had been followed over two years using the BSID-III, and the VABS-II. Previously findings were reported using age equivalent scores; now we are also presenting findings with GSVs. For the re-analysis, Language and Motor scores were added to the Cognitive scale on the BSID-III, and Domain- and Subdomain-level scores added to the Total VABS-II score (i.e., ABC Composite). We evaluated raw scores, age equivalent scores, and GSVs (and standard scores for the VABS-II only). Individual patient data can be found in the appendices to this publication. Results indicate that 1) Cognition as measured by GSVs was the most sensitive to decline; 2) GSVs showed significant decline in the range of 4 to 6 years of age; 3) For children under 4 years of age, positive growth occurs on most scales and most metrics, with the exception of language which slows somewhat earlier; 4) Other than the Cognitive scale, Receptive Language on the BSID-III and Receptive Communication on the VABS-II showed the most sensitivity to change; 5) Gross Motor skills showed the least decline over time and appeared to lack sensitivity to MPS IIIA motor concerns; and 6) No evidence for sensitivity to change for any metric was found in time intervals less than one year. We conclude that GSVs are a precise measurement of change to detect decline in function, and they are a valuable method for future clinical trials in MPS IIIA. Evidence continues to support cognition as a primary endpoint. Additional work is needed to identify sensitive measures of meaningful endpoints to families.

Low-molecular weight sulfated marine polysaccharides: Promising molecules to prevent neurodegeneration in mucopolysaccharidosis IIIA?

Mucopolysaccharidosis IIIA is a hereditary disease caused by mutations in the sulfamidase enzyme that participates in catabolism of heparan sulfate (HS), leading to HS fragment accumulation and multisystemic failure. No cure exists and death occurs around the second decade of life. Two low molecular weight highly sulfated compounds derived from marine diabolican and infernan exopolysaccharides (A5_3 and A5_4, respectively) with heparanase inhibiting properties were tested in a MPSIIIA cell line model, resulting in limited degradation of intracellular HS. Next, we observed the effects of intraperitoneal injections of the diabolican derivative A5_3 from 4 to 12 weeks of age on MPSIIIA mice. Brain metabolism and microstructure, levels of proteins and genes involved in MPSIIIA brain pathophysiology were also investigated. 1H-Magnetic Resonance Spectroscopy (MRS) indicated deficits in energetic metabolism, tissue integrity and neurotransmission at both 4 and 12 weeks in MPSIIIA mice, with partial protective effects of A5_3. Ex-vivo Diffusion Tensor Imaging (DTI) showed white matter microstructural damage in MPSIIIA, with noticeable protective effects of A5_3. Protein and gene expression assessments displayed both pro-inflammatory and pro-apoptotic profiles in MPSIIIA mice, with benefits of A5_3 counteracting neuroinflammation. Overall, derivative A5_3 was well tolerated and was shown to be efficient in preventing brain metabolism failure and inflammation, resulting in preserved brain microstructure in the context of MPSIIIA.

Economic Burden of Sanfilippo Syndrome in the United States

Introduction

Sanfilippo syndrome is a rare disease and fatal genetic disorder with no FDA-approved treatment in the United States (US), and no comprehensive assessment of economic disease burden is available.

Objectives

To develop a model to estimate the economic burden associated with Sanfilippo syndrome in the US using direct costs, indirect costs and valued intangibles (disability-adjusted life years, or DALYs) from 2023 onward.

Design and Setting

A multistage comorbidity model was generated based on Sanfilippo syndrome symptoms, and disability weights from the 2010 Global Burden of Disease Study. Attributable increase in caregiver mental health burden were estimated using data from the CDC National Comorbidity Survey and retrospective studies on caregiver burden. Direct costs were approximated from the 2019 EveryLife Foundation survey, and indirect costs were estimated from Federal income data. Monetary valuations were adjusted to USD 2023 and given a 3% discount rate from 2023 onward.

Main Outcome Measures

Incidence of Sanfilippo syndrome was calculated for each year, and year-over-year DALYs due to patient years lived with disability (YLDs) and years life lost (YLLs) were calculated by comparing to the health-adjusted life expectancy (HALE) in the US. Direct and indirect costs were calculated for each simulated patient from onset of symptoms to death.

Results

From 2023-2043, overall economic burden in the US attributable to Sanfilippo syndrome was estimated to be $2.04 billion USD present value (2023) with current standard of care. The burden to individual families exceeded $8 million present value from time of birth per child born with Sanfilippo syndrome.

Conclusion

Sanfilippo syndrome is a rare lysosomal storage disease, however the severe burden associated with the disease for individual families demonstrates a considerable cumulative impact. Our model represents the first disease burden value estimate associated with Sanfilippo syndrome, and underscores the substantial morbidity and mortality burden of Sanfilippo syndrome.

An immune deficient mouse model for mucopolysaccharidosis IIIA (Sanfilippo syndrome)

Mucopolysaccharidosis III (MPSIII, Sanfilippo syndrome) is a devastating lysosomal storage disease that primarily affects the central nervous system. MPSIIIA is caused by loss-of-function mutations in the gene coding for sulfamidase (N-sulfoglucosamine sulfohydrolase/SGSH) resulting in SGSH enzyme deficiency, a buildup of heparin sulfate and subsequent neurodegeneration. There is currently no cure or disease modifying treatment for MPSIIIA. A mouse model for MPSIIIA was characterized in 1999 and later backcrossed onto the C57BL/6 background. In the present study, a novel immune deficient MPSIIIA mouse model (MPSIIIA-TKO) was created by backcrossing the immune competent, C57BL/6 MPSIIIA mouse to an immune deficient mouse model lacking Rag2, CD47 and Il2rg genes. The resulting mouse model has undetectable SGSH activity, exhibits histological changes consistent with MPSIIIA and lacks T cells, B cells and NK cells. This new mouse model has the potential to be extremely useful in testing human cellular therapies in an animal model as it retains the MPSIIIA disease phenotype while tolerating xenotransplantation.

Disease pathology signatures in a mouse model of Mucopolysaccharidosis type IIIB

Mucopolysaccharidosis type IIIB (MPS IIIB) is a rare and devastating childhood-onset lysosomal storage disease caused by complete loss of function of the lysosomal hydrolase α-N-acetylglucosaminidase. The lack of functional enzyme in MPS IIIB patients leads to the progressive accumulation of heparan sulfate throughout the body and triggers a cascade of neuroinflammatory and other biochemical processes ultimately resulting in severe mental impairment and early death in adolescence or young adulthood. The low prevalence and severity of the disease has necessitated the use of animal models to improve our knowledge of the pathophysiology and for the development of therapeutic treatments. In this study, we took a systematic approach to characterizing a classical mouse model of MPS IIIB. Using a series of histological, biochemical, proteomic and behavioral assays, we tested MPS IIIB mice at two stages: during the pre-symptomatic and early symptomatic phases of disease development, in order to validate previously described phenotypes, explore new mechanisms of disease pathology and uncover biomarkers for MPS IIIB. Along with previous findings, this study helps provide a deeper understanding of the pathology landscape of this rare disease with high unmet medical need and serves as an important resource to the scientific community.

N-Substituted l-Iminosugars for the Treatment of Sanfilippo Type B Syndrome

Sanfilippo syndrome comprises a group of four genetic diseases due to the lack or decreased activity of enzymes involved in heparan sulfate (HS) catabolism. HS accumulation in lysosomes and other cellular compartments results in tissue and organ dysfunctions, leading to a wide range of clinical symptoms including severe neurodegeneration. To date, no approved treatments for Sanfilippo disease exist. Here, we report the ability of N-substituted l-iminosugars to significantly reduce substrate storage and lysosomal dysfunctions in Sanfilippo fibroblasts and in a neuronal cellular model of Sanfilippo B subtype. Particularly, we found that they increase the levels of defective α-N-acetylglucosaminidase and correct its proper sorting toward the lysosomal compartment. Furthermore, l-iminosugars reduce HS accumulation by downregulating protein levels of exostosin glycosyltransferases. These results highlight an interesting pharmacological potential of these glycomimetics in Sanfilippo syndrome, paving the way for the development of novel therapeutic approaches for the treatment of such incurable disease.

Activities of (Poly)phenolic Antioxidants and Other Natural Autophagy Modulators in the Treatment of Sanfilippo Disease: Remarkable Efficacy of Resveratrol in Cellular and Animal Models

Sanfilippo disease, caused by mutations in the genes encoding heparan sulfate (HS) (a glycosaminoglycan; GAG) degradation enzymes, is a mucopolysaccharidosis (MPS), which is also known as MPS type III, and is characterized by subtypes A, B, C, and D, depending on identity of the dysfunctional enzyme. The lack of activity or low residual activity of an HS-degrading enzyme leads to excess HS in the cells, impairing the functions of different types of cells, including neurons. The disease usually leads to serious psychomotor dysfunction and death before adulthood. In this work, we show that the use of molecules known as dietary (poly)phenolic antioxidants and other natural compounds known as autophagy activators (genistein, capsaicin, curcumin, resveratrol, trehalose, and calcitriol) leads to accelerated degradation of accumulated HS in the fibroblasts of all subtypes of MPS III. Both the cytotoxicity tests we performed and the available literature data indicated that the use of selected autophagy inducers was safe. Since it showed the highest effectivity in cellular models, resveratrol efficacy was tested in experiments with a mouse model of MPS IIIB. Urinary GAG levels were normalized in MPS IIIB mice treated with 50 mg/kg/day resveratrol for 12 weeks or longer. Behavioral tests indicated complete correction of hyperactivity and anxiety in these animals. Biochemical analyses indicated that administration of resveratrol caused autophagy stimulation through an mTOR-independent pathway in the brains and livers of the MPS IIIB mice. These results indicate the potential use of resveratrol (and possibly other autophagy stimulators) in the treatment of Sanfilippo disease.

Chemically modified recombinant human sulfamidase (SOBI003) in mucopolysaccharidosis IIIA patients: Results from an open, non-controlled, multicenter study

PURPOSE

Mucopolysaccharidosis IIIA (MPS IIIA) is an inherited lysosomal storage disorder caused by mutations in the N-sulfoglucosamine sulfohydrolase gene that result in deficient enzymatic degradation of heparan sulfate (HS), resulting in progressive neurodegeneration in early childhood and premature death. A chemically modified variant of recombinant human sulfamidase, SOBI003, has shown to cross the blood-brain barrier (BBB) in mice and achieve pharmacologically relevant levels in cerebrospinal fluid (CSF). We report on a phase 1/2, open-label, first-in-human (FIH) study (NCT03423186) and its extension study (NCT03811028) to evaluate the long-term safety, tolerability, pharmacokinetics/pharmacodynamics (PK/PD) and clinical efficacy of SOBI003 in patients with MPS IIIA for up to 104 weeks.

METHODS

Six patients aged 1-6 years with confirmed MPS IIIA with developmental age ≥ 12 months received weekly intravenous injections of SOBI003 at 3 mg/kg (Cohort 1, n = 3) or 10 mg/kg (Cohort 2, n = 3). During the extension study, the individual dose of SOBI003 could be adjusted up to 20 mg/kg at the discretion of the investigator.

RESULTS

SOBI003 was generally well tolerated. Serum concentrations of SOBI003 increased in proportion to dose, and presence in CSF confirmed that SOBI003 crosses the BBB. Anti-drug antibodies (ADA) were detected in serum and CSF in all patients, with subsequent reductions in serum SOBI003 exposure at high ADA titers. SOBI003 exerted a clear PD effect: a mean reduction in HS levels in CSF of 79% was recorded at the last assessment, together with reductions in HS levels in serum and urine. Neurocognitive development age-equivalent scores showed a stabilization of cognition for all patients, whereas no clear overall clinical effect was observed on adaptive behavior, sleep pattern or quality of life.

CONCLUSION

SOBI003 was well tolerated when administered as weekly intravenous infusions at doses of up to 20 mg/kg for up to 104 weeks. ADA development was common and likely affected both PK and PD parameters. SOBI003 crossed the BBB and showed pharmacological activity on HS in CSF.

Splicing Modulation as a Promising Therapeutic Strategy for Lysosomal Storage Disorders: The Mucopolysaccharidoses Example

Over recent decades, the many functions of RNA have become more evident. This molecule has been recognized not only as a carrier of genetic information, but also as a specific and essential regulator of gene expression. Different RNA species have been identified and novel and exciting roles have been unveiled. Quite remarkably, this explosion of novel RNA classes has increased the possibility for new therapeutic strategies that tap into RNA biology. Most of these drugs use nucleic acid analogues and take advantage of complementary base pairing to either mimic or antagonize the function of RNAs. Among the most successful RNA-based drugs are those that act at the pre-mRNA level to modulate or correct aberrant splicing patterns, which are caused by specific pathogenic variants. This approach is particularly tempting for monogenic disorders with associated splicing defects, especially when they are highly frequent among affected patients worldwide or within a specific population. With more than 600 mutations that cause disease affecting the pre-mRNA splicing process, we consider lysosomal storage diseases (LSDs) to be perfect candidates for this type of approach. Here, we introduce the overall rationale and general mechanisms of splicing modulation approaches and highlight the currently marketed formulations, which have been developed for non-lysosomal genetic disorders. We also extensively reviewed the existing preclinical studies on the potential of this sort of therapeutic strategy to recover aberrant splicing and increase enzyme activity in our diseases of interest: the LSDs. Special attention was paid to a particular subgroup of LSDs: the mucopolysaccharidoses (MPSs). By doing this, we hoped to unveil the unique therapeutic potential of the use of this sort of approach for LSDs as a whole.

Heparan Sulfate, Mucopolysaccharidosis IIIB and Sulfur Metabolism Disorders

Mucopolysaccharidosis, type IIIB (MPS IIIB) is a rare disease caused by mutations in the N-alpha-acetylglucosaminidase (NAGLU) gene resulting in decreased or absent enzyme activity. On the cellular level, the disorder is characterized by the massive lysosomal storage of heparan sulfate (HS)—one species of glycosaminoglycans. HS is a sulfur-rich macromolecule, and its accumulation should affect the turnover of total sulfur in cells; according to the studies presented here, it, indeed, does. The lysosomal degradation of HS in cells produces monosaccharides and inorganic sulfate (SO₄²⁻). Sulfate is a product of L-cysteine metabolism, and any disruption of its levels affects the entire L-cysteine catabolism pathway, which was first reported in 2019. It is known that L-cysteine level is elevated in cells with the Naglu^−/− gene mutation and in selected tissues of individuals with MPS IIIB. The level of glutathione and the Naglu^−/− cells’ antioxidant potential are significantly reduced, as well as the activity of 3-mercaptopyruvate sulfurtransferase (MPST, EC 2.8.1.2) and the level of sulfane sulfur-containing compounds. The direct reason is not yet known. This paper attempts to identify some of cause-and-effect correlations that may lead to this condition and identifies research directions that should be explored.

Sanfilippo syndrome type B: Analysis of patients diagnosed by the MPS Brazil Network

Mucopolysaccharidosis type IIIB is a rare autosomal recessive disorder characterized by deficiency of the enzyme N-acetyl-alpha-d-glucosaminidase (NAGLU), caused by biallelic pathogenic variants in the NAGLU gene, which leads to storage of heparan sulfate and a series of clinical consequences which hallmark is neurodegeneration. In this study clinical, epidemiological, and biochemical data were obtained from MPS IIIB patients diagnosed from 2004-2019 by the MPS Brazil Network ("Rede MPS Brasil"), which was created with the goal to provide an easily accessible and comprehensive investigation of all MPS types. One hundred and ten MPS IIIB patients were diagnosed during this period. Mean age at diagnosis was 10.9 years. Patients were from all over Brazil, with a few from abroad, with a possible cluster of MPS IIIB identified in Ecuador. All patients had increased urinary levels of glycosaminoglycans and low NAGLU activity in blood. Main clinical symptoms reported at diagnosis were coarse facies and neurocognitive regression. The most common variant was p.Leu496Pro (30% of alleles). MPS IIIB seems to be relatively frequent in Brazil, but patients are diagnosed later than in other countries, and reasons for that probably include the limited awareness about the disease by health professionals and the difficulties to access diagnostic tests, factors that the MPS Brazil Network is trying to mitigate.

Current and Future Prospects for Gene Therapy for Rare Genetic Diseases Affecting the Brain and Spinal Cord

In recent years, gene therapy has been raising hopes toward viable treatment strategies for rare genetic diseases for which there has been almost exclusively supportive treatment. We here review this progress at the pre-clinical and clinical trial levels as well as market approvals within diseases that specifically affect the brain and spinal cord, including degenerative, developmental, lysosomal storage, and metabolic disorders. The field reached an unprecedented milestone when Zolgensma® (onasemnogene abeparvovec) was approved by the FDA and EMA for in vivo adeno-associated virus-mediated gene replacement therapy for spinal muscular atrophy. Shortly after EMA approved Libmeldy®, an ex vivo gene therapy with lentivirus vector-transduced autologous CD34-positive stem cells, for treatment of metachromatic leukodystrophy. These successes could be the first of many more new gene therapies in development that mostly target loss-of-function mutation diseases with gene replacement (e.g., Batten disease, mucopolysaccharidoses, gangliosidoses) or, less frequently, gain-of-toxic-function mutation diseases by gene therapeutic silencing of pathologic genes (e.g., amyotrophic lateral sclerosis, Huntington's disease). In addition, the use of genome editing as a gene therapy is being explored for some diseases, but this has so far only reached clinical testing in the treatment of mucopolysaccharidoses. Based on the large number of planned, ongoing, and completed clinical trials for rare genetic central nervous system diseases, it can be expected that several novel gene therapies will be approved and become available within the near future. Essential for this to happen is the in depth characterization of short- and long-term effects, safety aspects, and pharmacodynamics of the applied gene therapy platforms.

Disease modeling for Mucopolysaccharidosis type IIIB using patient derived induced pluripotent stem cells

Mucopolysaccharidosis type IIIB (MPS IIIB) is a lysosomal disease caused by mutations in the NAGLU gene encoding α-N-acetylglucosaminidase (NAGLU) which degrades heparan sulfate in lysosomes. Deficiency in NAGLU results in lysosomal accumulation of glycosaminoglycans (GAGs) and neurological symptoms. Currently, there is no effective treatment or cure for this disease. In this study, induced pluripotent stem cell lines were established from two MPS IIIB patient fibroblast lines and differentiated into neural stem cells and neurons. MPS IIIB neural stem cells exhibited NAGLU deficiency accompanied with GAG accumulation, as well as lysosomal enlargement and secondary lipid accumulation. Treatments with recombinant NAGLU, δ-tocopherol, and 2-hydroxypropyl-b-cyclodextrin significantly reduced the disease phenotypes in these cells. These results indicate the MPS IIIB neural stem cells and neurons have the disease relevant phenotype and can be used as a cell-based disease model system for evaluation of drug efficacy and compound screening for drug development.

Competitive binding of extracellular accumulated heparan sulfate reduces lysosomal storage defects and triggers neuronal differentiation in a model of Mucopolysaccharidosis IIIB

Mucopolysaccharidoses (MPSs) are a group of inherited lysosomal storage disorders associated with the deficiency of lysosomal enzymes involved in glycosaminoglycan (GAG) degradation. The resulting cellular accumulation of GAGs is responsible for widespread tissue and organ dysfunctions. The MPS III, caused by mutations in the genes responsible for the degradation of heparan sulfate (HS), includes four subtypes (A, B, C, and D) that present significant neurological manifestations such as progressive cognitive decline and behavioral disorders. The established treatments for the MPS III do not cure the disease but only ameliorate non-neurological clinical symptoms. We previously demonstrated that the natural variant of the hepatocyte growth factor NK1 reduces the lysosomal pathology and reactivates impaired growth factor signaling in fibroblasts from MPS IIIB patients. Here, we show that the recombinant NK1 is effective in rescuing the morphological and functional dysfunctions of lysosomes in a neuronal cellular model of the MPS IIIB. More importantly, NK1 treatment is able to stimulate neuronal differentiation of neuroblastoma SK-NBE cells stable silenced for the NAGLU gene causative of the MPS IIIB. These results provide the basis for the development of a novel approach to possibly correct the neurological phenotypes of the MPS IIIB as well as of other MPSs characterized by the accumulation of HS and progressive neurodegeneration.

Evolving AAV-delivered therapeutics towards ultimate cures

Gene therapy has entered a new era after decades-long efforts, where the recombinant adeno-associated virus (AAV) has stood out as the most potent vector for in vivo gene transfer and demonstrated excellent efficacy and safety profiles in numerous preclinical and clinical studies. Since the first AAV-derived therapeutics Glybera was approved by the European Medicines Agency (EMA) in 2012, there is an increasing number of AAV-based gene augmentation therapies that have been developed and tested for treating incurable genetic diseases. In the subsequent years, the United States Food and Drug Administration (FDA) approved two additional AAV gene therapy products, Luxturna and Zolgensma, to be launched into the market. Recent breakthroughs in genome editing tools and the combined use with AAV vectors have introduced new therapeutic modalities using somatic gene editing strategies. The promising outcomes from preclinical studies have prompted the continuous evolution of AAV-delivered therapeutics and broadened the scope of treatment options for untreatable diseases. Here, we describe the clinical updates of AAV gene therapies and the latest development using AAV to deliver the CRISPR components as gene editing therapeutics. We also discuss the major challenges and safety concerns associated with AAV delivery and CRISPR therapeutics, and highlight the recent achievement and toxicity issues reported from clinical applications.

New paradigms for the treatment of lysosomal storage diseases: targeting the endocannabinoid system as a therapeutic strategy

Over the past three decades the lysosomal storage diseases have served as model for rare disease treatment development. While these efforts have led to considerable success, important challenges remain. For example, no treatments are currently approved for nearly two thirds of all lysosomal diseases, and there is limited impact of the existing drugs on the central nervous system. In addition, the costs of these therapies are extremely high, in part due to the fact that drug development has focused on a "single hit" approach - i.e., one drug for one disease. To overcome these obstacles researchers have begun to focus on defining common disease mechanisms in the lysosomal diseases, particularly in the central nervous system, with the hope of identifying drugs that might be used in several lysosomal diseases rather than an individual disease. With this concept in mind, herein we review a new potential treatment approach for the lysosomal storage diseases that focuses on modulation of the endocannabinoid system. We provide a short introduction to lysosomal storage diseases and the endocannabinoid system, followed by a brief review of data supporting this concept.