Infusion of alpha-galactosidase A reduces tissue globotriaosylceramide storage in patients with Fabry disease

Targeted ADAMTS-13 replacement therapy for thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura (TTP) is a life-threatening thrombotic disorder associated with a severe deficiency of ADAMTS-13-the protease that cleaves von Willebrand factor. Plasma therapy is the current standard of care for managing acute episodes of TTP, which involves removing patient plasma and replacing it with donor plasma to raise the level of ADAMTS-13 activity. Recently, therapies aimed at replacing ADAMTS-13 have been investigated as possible substitutes or add-ons to plasma therapy for congenital and immune-mediated TTP. Enzyme replacement therapy provides recombinant ADAMTS-13 via intravenous (i.v.) infusion to restore enzyme activity. Recombinant ADAMTS-13-loaded platelets localize to the site of thrombus formation in a more concentrated manner than enzyme replacement or plasma therapy. ADAMTS-13-encoding messenger RNA aims to induce a steady supply of secreted protein and gene therapy is a potentially curative strategy. Overall, targeted ADAMTS-13 replacement therapies may provide better outcomes than plasma therapy by achieving higher levels of ADAMTS-13 activity and a more sustained response with fewer adverse events. Herein, we describe targeted ADAMTS-13 replacement therapies for the treatment of TTP and discuss the advantages and limitations of each approach.

Evaluating the Metabolic Basis of α-Gal A mRNA Therapy for Fabry Disease

mRNA injection-based protein supplementation has emerged as a feasible treatment for Fabry disease. However, whether the introduction of LNP-encapsulated mRNA results in the alteration of metabolomics in an in vivo system remains largely unknown. In the present study, α-galactosidase A (α-Gal A) mRNA was generated and injected into the Fabry disease mouse model. The α-Gal A protein was successfully expressed. The level of globotriaosylsphingosine (Lyso-Gb3), a biomarker for Fabry disease, as well as pro-inflammatory cytokines such as nuclear factor kappa-B (NF-κB), interleukin 6 (IL-6), and tumor necrosis factor-α (TNF-α), were greatly decreased compared to the untreated control, indicating the therapeutic outcome of the mRNA drug. Metabolomics analysis found that the level of 20 metabolites was significantly altered in the plasma of mRNA-injected mice. These compounds are primarily enriched in the arachidonic acid metabolism, alanine, aspartate and glutamate metabolism, and glycolysis/gluconeogenesis pathways. Arachidonic acid and 5-hydroxyeicosatetraenoic acid (5-HETE), both of which are important components in the eicosanoid pathway and related to inflammation response, were significantly increased in the injected mice, possibly due to the presence of lipid nanoparticles. Moreover, mRNA can effectively alter the level of metabolites in the amino acid and energy metabolic pathways that are commonly found to be suppressed in Fabry disease. Taken together, the present study demonstrated that in addition to supplementing the deficient α-Gal A protein, the mRNA-based therapeutic agent can also affect levels of metabolites that may help in the recovery of metabolic homeostasis in the full body system.

Anderson-Fabry Disease: Red Flags for Early Diagnosis of Cardiac Involvement

Anderson-Fabry disease (AFD) is a lysosome storage disorder resulting from an X-linked inheritance of a mutation in the galactosidase A (GLA) gene encoding for the enzyme alpha-galactosidase A (α-GAL A). This mutation results in a deficiency or absence of α-GAL A activity, with a progressive intracellular deposition of glycosphingolipids leading to organ dysfunction and failure. Cardiac damage starts early in life, often occurring sub-clinically before overt cardiac symptoms. Left ventricular hypertrophy represents a common cardiac manifestation, albeit conduction system impairment, arrhythmias, and valvular abnormalities may also characterize AFD. Even in consideration of pleiotropic manifestation, diagnosis is often challenging. Thus, knowledge of cardiac and extracardiac diagnostic "red flags" is needed to guide a timely diagnosis. Indeed, considering its systemic involvement, a multidisciplinary approach may be helpful in discerning AFD-related cardiac disease. Beyond clinical pearls, a practical approach to assist clinicians in diagnosing AFD includes optimal management of biochemical tests, genetic tests, and cardiac biopsy. We extensively reviewed the current literature on AFD cardiomyopathy, focusing on cardiac "red flags" that may represent key diagnostic tools to establish a timely diagnosis. Furthermore, clinical findings to identify patients at higher risk of sudden death are also highlighted.

The Importance of Early Treatment of Inherited Neuromuscular Conditions

There has been tremendous progress in treatment of neuromuscular diseases over the last 20 years, which has transformed the natural history of these severely debilitating conditions. Although the factors that determine the response to therapy are many and in some instance remain to be fully elucidated, early treatment clearly has a major impact on patient outcomes across a number of inherited neuromuscular conditions. To improve patient care and outcomes, clinicians should be aware of neuromuscular conditions that require prompt treatment initiation. This review describes data that underscore the importance of early treatment of children with inherited neuromuscular conditions with an emphasis on data resulting from newborn screening efforts.

Novel enhancer mediates the RPL36A-HNRNPH2 readthrough loci and GLA gene expressions associated with fabry disease

Fabry disease (FD) is a rare genetic condition caused by mutations in the GLA gene, located on the X chromosome in the RPL36-HNRNPH2 readthrough genomic region. This gene produces an enzyme called alpha-galactosidase A (α-Gal A). When the enzyme does not function properly due to the mutations, it causes harmful substances called globotriaosylceramide (Gb3) and globotriaosylsphingosine (lyso-Gb3) to build up in the body's lysosomes. This accumulation can damage the kidneys, heart, eyes, and nervous system. Recent studies have shown that the RPL36A-HNRNPH2 readthrough loci, which include RPL36A and HNRNPH2 genes, as well as the regulatory sequence known as the GLA-HNRNPH2 bidirectional promoter, may also play a role in FD. However, the involvement of enhancer RNAs (eRNAs) in FD is still poorly understood despite their known role in various diseases. To investigate this further, we studied an RPL36A enhancer called GH0XJ101390 and showed its genomic setting in the RPL36-HNRNPH2 readthrough region; the eRNA is rich in Homotypic Clusters of TFBSs (HCTs) type and hosts a CpG Island (CGI). To test the functional correlation further with GLA, RPL36A, and HNRNPH2, we used siRNAs to knock down GH0XJ101390 in human kidney embryonic cells 293T. The results showed a significant decrease in RPL36A and GLA expression and a non-significant decrease in HNRNPH2 expression. These findings could have important implications for understanding the regulatory mechanisms of GH0XJ101390 and its potential role in FD. A better understanding of these mechanisms may improve diagnostic and therapeutic methods for FD, which could ultimately benefit patients with this rare condition.

Glycosylation shapes the efficacy and safety of diverse protein, gene and cell therapies

Over recent decades, therapeutic proteins have had widespread success in treating a myriad of diseases. Glycosylation, a near universal feature of this class of drugs, is a critical quality attribute that significantly influences the physical properties, safety profile and biological activity of therapeutic proteins. Optimizing protein glycosylation, therefore, offers an important avenue to developing more efficacious therapies. In this review, we discuss specific examples of how variations in glycan structure and glycoengineering impacts the stability, safety, and clinical efficacy of protein-based drugs that are already in the market as well as those that are still in preclinical development. We also highlight the impact of glycosylation on next generation biologics such as T cell-based cancer therapy and gene therapy.

Population Frequency of Undiagnosed Fabry Disease in the General Population

Introduction

Fabry disease is an X-linked disorder that results from pathogenic GLA variants and can now be treated. Most studies of its population frequency have examined only males or attendees at kidney failure or cardiac clinics. This study determined the prevalence of undiagnosed Fabry disease from predicted pathogenic GLA variants in the general population.

Methods

The Genome Aggregation Database (gnomAD) was examined for predicted pathogenic GLA variants based on variant rarity (≤5), and transcript effect in 4 computational tools (CADD >20, PP2 >0.95, SIFT <0.05, Mutation Taster - Disease-causing) and amino acid conservation in vertebrates in a Clustal.

Results

Predicted pathogenic variants in GLA occurred in 1 in 3225 of the gnomAD population and 1 in 3478 of its control subset. Predicted pathogenic variants were more common in women than expected (3.1:1), which is consistent with men being excluded from gnomAD because of Fabry complications. Predicted pathogenic variants were not found in members of this cohort with South Asian, Ashkenazim, or Finnish ancestries. Variants identified as pathogenic in the Fabry database were found in 1 in 2651 individuals of the gnomAD database and pathogenic variants from ClinVar in 1 in 4420.

Discussion

The population frequency of 1 in 3225 for undiagnosed men and women with Fabry disease still represents an underestimate because our pathogenicity criteria were rigorous, the cohort did not include already-diagnosed individuals, and whole exome sequencing does not detect intronic variants and large deletions. This study confirms that Fabry disease is more common than previously recognized and still underdiagnosed especially in women.

Newborn Screening for Fabry Disease: Current Status of Knowledge

Fabry disease is an X-linked progressive lysosomal disorder, due to α-galactosidase A deficiency. Patients with a classic phenotype usually present in childhood as a multisystemic disease. Patients presenting with the later onset subtypes have cardiac, renal and neurological involvements in adulthood. Unfortunately, the diagnosis is often delayed until the organ damage is already irreversibly severe, making specific treatments less efficacious. For this reason, in the last two decades, newborn screening has been implemented to allow early diagnosis and treatment. This became possible with the application of the standard enzymology fluorometric method to dried blood spots. Then, high-throughput multiplexable assays, such as digital microfluidics and tandem mass spectrometry, were developed. Recently DNA-based methods have been applied to newborn screening in some countries. Using these methods, several newborn screening pilot studies and programs have been implemented worldwide. However, several concerns persist, and newborn screening for Fabry disease is still not universally accepted. In particular, enzyme-based methods miss a relevant number of affected females. Moreover, ethical issues are due to the large number of infants with later onset forms or variants of uncertain significance. Long term follow-up of individuals detected by newborn screening will improve our knowledge about the natural history of the disease, the phenotype prediction and the patients' management, allowing a better evaluation of risks and benefits of the newborn screening for Fabry disease.

Fabry Disease: Current and Novel Therapeutic Strategies. A Narrative Review

BACKGROUND

Fabry disease (FD) is an inherited lysosomal storage disorder, leading to multisystemic manifestations and causing significant morbidity and mortality.

OBJECTIVE

The aim of this narrative review is to present the current and novel therapeutic strategies in FD, including symptomatic and specific treatment options.

METHODS

A systematic literature search was conducted to identify relevant studies, including completed and ongoing randomized-controlled clinical trials (RCTs), prospective or retrospective cohort studies, case series and case reports that provided clinical data regarding FD treatment.

RESULTS

A multidisciplinary symptomatic treatment is recommended for FD patients, personalized according to disease manifestations and their severity. During the last two decades, FD-specific treatments, including two enzyme-replacement-therapies (agalsidase alfa and agalsidase beta) and chaperone treatment with migalastat have been approved for use and allowed for symptoms' stabilization or even disease burden reduction. More therapeutic agents are currently under investigation. Substrate reduction therapies, including lucerastat and venglustat, have shown promising results in RCTs and may be used either as monotherapy or as complementary therapy to established enzymereplacement- therapies. More stable enzyme-replacement-therapy molecules that are associated with less adverse events and lower likelihood of neutralizing antibodies formation have also been developed. Ex-vivo and in-vivo gene therapy is being tested in animal models and pilot human clinical trials, with preliminary results showing a favorable safety and efficacy profile.

CONCLUSION

The therapeutic landscape in FD appears to be actively expanding with more treatment options expected to become available in the near future, allowing for a more personalized approach in FD patients.

Automated urinary sediment detection for Fabry disease using deep-learning algorithms

Fabry disease is a congenital lysosomal storage disease, and most of these cases develop organ damage in middle age. There are some promising therapeutic options for this disorder, which can stabilize the progression of the disease. However, a long delay in diagnosis prevents early intervention, resulting in treatment failure. Because Fabry disease is a rare disease, it is not well recognized and disease specific screening tests are rarely performed. Hence, a novel approach to for detecting patients with a widely practiced clinical test is crucial for the early detection of the disease. Recently, decision support systems based on artificial intelligence (AI) have been developed in many clinical fields. However, the construction of these models requires datasets from a large number of samples; this aspect is one of the main obstacles in AI-based approaches for rare diseases. In this study, with a novel image amplification method to construct the dataset for AI-model training, we built the deep neural-network model to detect Fabry cases from their urine samples. Sensitivity, specificity, and the AUC of the models on validation dataset were 0.902 (95% CI, 0.900–0.903), 0.977 (0.950–0.980), and 0.968 (0.964–0.972), respectively. This model could also extract disease-specific findings that are interpretable with human recognition. These results indicate that we can apply novel AI models for rare diseases based on this image amplification method we developed. We expect this approach could contribute to the diagnosis of Fabry disease.

Synopsis

This is the first reported AI-based decision support system to detect undiagnosed Fabry cases, and our new image amplification method will contribute to the AI models for other rare disorders.

A phase II, multicenter, open-label trial to evaluate the safety and efficacy of ISU303 (Agalsidase beta) in patients with Fabry disease

BACKGROUND

Fabry disease (FD) is caused by a deficiency in the activity of the lysosomal enzyme, α-galactosidase A (α-Gal A), which leads to globotriaosylceramide (Gb3) deposition in multiple tissues. The current management of FD is enzyme replacement therapy (ERT). We report on the efficacy and safety of a new agalsidase beta, ISU303, in FD.

METHODS

Ten patients (7 males, 3 females) were enrolled and administered a 1 mg/kg dose of ISU303, every other week for 6 months. The primary endpoint was the normalization of plasma Gb3 level. The secondary endpoints were the changes from baseline in urine Gb3 and the plasma and urine lyso-globotriaosylsphingosine (lyso-Gb3) level. Echocardiography, renal function test, and pain-related quality of life were also assessed before and after administration. Safety evaluation was performed including vital signs, laboratory tests, electrocardiograms, antibody screening tests, and adverse events at each visit.

RESULTS

At 22 weeks of treatment, plasma and urine Gb3 level decreased by a mean of 4.01 ± 1.29 μg/mL (range 2.50-5.70) (P = .005) and 1.12 ± 1.98 μg/mg Cr. (range 0.04-5.65) (P = .017), respectively. However, no significant difference was observed in plasma and urine lyso-Gb3 levels. Echocardiography also was not changed. Renal function and pain-related quality of life showed improvements, but there was no clinical significance. No severe adverse events were observed. Only 1 patient developed an anti-drug antibody without neutralizing activity during the trial.

CONCLUSION

This study showed the efficacy and safety of ISU303. Treatment with ISU303 significantly resulted in plasma and urine Gb3 decrease in patients with FD. These results suggest that ISU303 is safe and effective and can alternative ERT for FD.

Left Ventricular Hypertrophy: Etiology-Based Therapeutic Options

Determining the etiologies of left ventricular hypertrophy (LVH) can be challenging due to the similarities of the different manifestations in clinical presentation and morphological features. Depending on the underlying cause, not only left ventricular mass but also left ventricular cavity size, or both, may increase. Patients with LVH remain asymptomatic for a few years, but disease progression will lead to the development of systolic or diastolic dysfunction and end-stage heart failure. As hypertrophied cardiac muscle disrupts normal conduction, LVH predisposes to arrhythmias. Distinguishing individuals with treatable causes of LVH is important for prevention of cardiovascular events and mortality. Athletic’s heart with physiological LVH does not require treatment. Frequent causes of hypertrophy include etiologies due to pressure/volume overload, such as systemic hypertension, hypertrophic cardiomyopathy, or infiltrative cardiac processes such as amyloidosis, Fabry disease, and sarcoidosis. Hypertension and aortic valve stenosis are the most common causes of LVH. Management of LVH involves lifestyle changes, medications, surgery, and implantable devices. In this review we systematically summarize treatments for the different patterns of cardiac hypertrophy and their impacts on outcomes while informing clinicians on advances in the treatment of LVH due to Fabry disease, cardiac amyloidosis, and hypertrophic cardiomyopathy.

Fabry Disease and the Effectiveness of Enzyme Replacement Therapy (ERT) in Left Ventricular Hypertrophy (LVH) Improvement: A Review and Meta-Analysis

Background: Fabry disease is an inherited lysosomal storage disease affecting multiple organs with complications, including cardiomyopathy such as left ventricular hypertrophy (LVH). Enzyme replacement therapy (ERT) has been the main treatment for Fabry patients since 2001. However, the indications of ERT are not clearly defined. We performed a meta-analysis according to previous studies to review the benefit of ERT for LVH improvement in Fabry patients. Methods: We performed a literature search from the National Center for Biotechnology Information (NCBI) and PubMed database without restriction of years for systematic review purposes. We performed a systematic review of clinical cohort studies and trials using a pooled analysis of proportions. We calculated the pooled proportions and the confidence intervals (CI) for left ventricular mass index (LVMI) for both ERT treatment and ERT treatment-naïve groups. The results for before ERT treatment and after ERT treatment are also investigated. Results: A total of 5 cohort studies and 2 randomized controlled trials (RCTs), involving a total of 552 participants (267 on ERT treatment versus 285 on naïve treatment), met the inclusion criteria. The pooled proportions analysis showed that the difference in means of LVMI between the ERT treatment group and the ERT treatment-naïve group was -0.149 [95% CI: -0.431, 0.132]. Effect differences favored the ERT treatment group over the ERT treatment-naïve group (p = 0.034). Another analysis included 3 cohort studies and 1 RCT with 442 participants (228 on before ERT and 214 on 4 years after ERT). The pooled proportions analysis showed that the difference in means of LVMI between the before ERT treatment group and the after ERT treatment group was -0.448 [95% CI: -0.787, -0.108]. It favored the 4 years after ERT group over the before ERT group (p = 0.037). Conclusions: Based on the currently available data, our meta-analysis showed that there are beneficial effects on LVH improvement with ERT in Fabry disease patients. It is better to start ERT as soon as we have diagnoses in female carriers and atypically affected males. Further research is needed to investigate the role of ERT in LVH improvement.

A Rapid and Simple UHPLC-MS/MS Method for Quantification of Plasma Globotriaosylsphingosine (lyso-Gb3)

Fabry disease (FD) is a rare X-linked lysosomal storage disorder caused by α-galactosidase A gene (GLA) mutations, resulting in loss of activity of the lysosomal hydrolase, α-galactosidase A (α-Gal A). As a result, the main glycosphingolipid substrates, globotriaosylceramide (Gb3) and globotriaosylsphingosine (lyso-Gb3), accumulate in plasma, urine, and tissues. Here, we propose a simple, fast, and sensitive method for plasma quantification of lyso-Gb3, the most promising secondary screening target for FD. Assisted protein precipitation with methanol using Phree cartridges was performed as sample pre-treatment and plasma concentrations were measured using UHPLC-MS/MS operating in MRM positive electrospray ionization. Method validation provided excellent results for the whole calibration range (0.25–100 ng/mL). Intra-assay and inter-assay accuracy and precision (CV%) were calculated as <10%. The method was successfully applied to 55 plasma samples obtained from 34 patients with FD, 5 individuals carrying non-relevant polymorphisms of the GLA gene, and 16 healthy controls. Plasma lyso-Gb3 concentrations were larger in both male and female FD groups compared to healthy subjects (p < 0.001). Normal levels of plasma lyso-Gb3 were observed for patients carrying non-relevant mutations of the GLA gene compared to the control group (p = 0.141). Dropping the lower limit of quantification (LLOQ) to 0.25 ng/mL allowed us to set the optimal plasma lyso-Gb3 cut-off value between FD patients and healthy controls at 0.6 ng/mL, with a sensitivity of 97.1%, specificity of 100%, and accuracy of 0.998 expressed by the area under the ROC curve (C.I. 0.992 to 1.000, p-value < 0.001). Based on the results obtained, this method can be a reliable tool for early phenotypic assignment, assessing diagnoses in patients with borderline GalA activity, and confirming non-relevant mutations of the GLA gene.

Newborn Screening for Fabry Disease in Northeastern Italy: Results of Five Years of Experience

Fabry disease (FD) is a progressive multisystemic lysosomal storage disease. Early diagnosis by newborn screening (NBS) may allow for timely treatment, thus preventing future irreversible organ damage. We present the results of 5.5 years of NBS for FD by α-galactosidase A activity and globotriaosylsphingosine (lyso-Gb₃) assays in dried blood spot through a multiplexed MS/MS assay. Furthermore, we report our experience with long-term follow-up of positive subjects. We screened more than 170,000 newborns and 22 males were confirmed to have a GLA gene variant, with an incidence of 1:7879 newborns. All patients were diagnosed with a variant previously associated with the later-onset phenotype of FD or carried an unclassified variant (four patients) or the likely benign p.Ala143Thr variant. All were asymptomatic at the last visit. Although lyso-Gb₃ is not considered a reliable second tier test for newborn screening, it can simplify the screening algorithm when its levels are elevated at birth. After birth, plasma lyso-Gb₃ is a useful marker for non-invasive monitoring of all positive patients. Our study is the largest reported to date in Europe, and presents data from long-term NBS for FD that reveals the current incidence of FD in northeastern Italy. Our follow-up data describe the early disease course and the trend of plasma lyso-Gb₃ during early childhood.

Enzyme Replacement Therapy for Genetic Disorders Associated with Enzyme Deficiency

Mutations in human genes might lead to loss of functional proteins, causing diseases. Among these genetic disorders, a large class is associated with the deficiency in metabolic enzymes, resulting in both an increase in the concentration of substrates and a loss in the metabolites produced by the catalyzed reactions. The identification of therapeutic actions based on small molecules represents a challenge to medicinal chemists because the target is missing. Alternative approaches are biology-based, ranging from gene and stem cell therapy, CRISPR/Cas9 technology, distinct types of RNAs, and enzyme replacement therapy (ERT). This review will focus on the latter approach that since the 1990s has been successfully applied to cure many rare diseases, most of them being lysosomal storage diseases or metabolic diseases. So far, a dozen enzymes have been approved by FDA/EMA for lysosome storage disorders and only a few for metabolic diseases. Enzymes for replacement therapy are mainly produced in mammalian cells and some in plant cells and yeasts and are further processed to obtain active, highly bioavailable, less degradable products. Issues still under investigation for the increase in ERT efficacy are the optimization of enzymes interaction with cell membrane and internalization, the reduction in immunogenicity, and the overcoming of blood-brain barrier limitations when neuronal cells need to be targeted. Overall, ERT has demonstrated its efficacy and safety in the treatment of many genetic rare diseases, both saving newborn lives and improving patients' life quality, and represents a very successful example of targeted biologics.

Biomarkers in Anderson-Fabry Disease

Fabry disease is a rare lysosomal storage disorder caused by a deficiency of α-galactosidase A, resulting in multisystemic involvement. Lyso-Gb3 (globotriaosylsphingosine), the deacylated form of Gb3, is currently measured in plasma as a biomarker of classic Fabry disease. Intensive research of biomarkers has been conducted over the years, in order to detect novel markers that may potentially be used in clinical practice as a screening tool, in the context of the diagnostic process and as an indicator of response to treatment. An interesting field of application of such biomarkers is the management of female heterozygotes who present difficulty in predictable clinical progression. This review aims to summarise the current evidence and knowledge about general and specific markers that are actually measured in subjects with confirmed or suspected Fabry disease; moreover, we report potential novel markers such as microRNAs. Recent proteomic or metabolomic studies are in progress bringing out plasma proteome profiles in Fabry patients: this assessment may be useful to characterize molecular pathology of the disease, to improve diagnostic process, and to monitor response to treatment. The management of Fabry disease may be improved by the identification of biomarkers that reflect clinical course, severity, and the progression of the disease.

Long-term efficacy and safety of migalastat treatment in Fabry disease: 30-month results from the open-label extension of the randomized, phase 3 ATTRACT study

Results from the 18-month randomized treatment period of the phase 3 ATTRACT study demonstrated the efficacy and safety of oral migalastat compared with enzyme replacement therapy (ERT) in patients with Fabry disease who previously received ERT. Here, we report data from the subsequent 12-month, migalastat-only, open-label extension (OLE) period. ATTRACT (Study AT1001-012; NCT01218659) was a randomized, open-label, active-controlled study in patients aged 16-74 years with Fabry disease, an amenable GLA variant, and an estimated glomerular filtration rate (eGFR) ≥30 mL/min/1.73 m². During the OLE, patients who received migalastat 150 mg every other day (QOD) during the randomized period continued receiving migalastat (Group 1 [MM]); patients who received ERT every other week discontinued ERT and started migalastat treatment (Group 2 [EM]). Outcome measures included eGFR, left ventricular mass index (LVMi), composite clinical outcome (renal, cardiac or cerebrovascular events), and safety. Forty-six patients who completed the randomized treatment period continued into the OLE (Group 1 [MM], n = 31; Group 2 [EM], n = 15). eGFR remained stable in both treatment groups. LVMi decreased from baseline at month 30 in Group 1 (MM) in patients with left ventricular hypertrophy at baseline. Only 10% of patients experienced a new composite clinical event with migalastat treatment during the OLE. No new safety concerns were reported. In conclusion, in patients with Fabry disease and amenable GLA variants, migalastat 150 mg QOD was well tolerated and demonstrated durable, long-term stability of renal function and reduction in LVMi.

Developments in the treatment of Fabry disease

Enzyme replacement therapy (ERT) with recombinant α-galactosidase A (r-αGAL A) for the treatment of Fabry disease has been available for over 15 years. Long-term treatment may slow down disease progression, but cardiac, renal, and cerebral complications still develop in most patients. In addition, lifelong intravenous treatment is burdensome. Therefore, several new treatment approaches have been explored over the past decade. Chaperone therapy (Migalastat; 1-deoxygalactonojirimycin) is the only other currently approved therapy for Fabry disease. This oral small molecule aims to improve enzyme activity of mutated α-galactosidase A and can only be used in patients with specific mutations. Treatments currently under evaluation in (pre)clinical trials are second generation enzyme replacement therapies (Pegunigalsidase-alfa, Moss-aGal), substrate reduction therapies (Venglustat and Lucerastat), mRNA- and gene-based therapy. This review summarises the knowledge on currently available and potential future options for the treatment of Fabry disease.

Rare Etiology of Renal Failure in a 25-Year-Old Caucasian Man: Fabry Disease With a Novel Mutation of GLA Gene

Fabry disease (FD) is an X-linked recessive lysosomal storage disease caused by a mutation of the galactosidase alpha (GLA) gene, leading to deficiency of α-galactosidase A (alpha-Gal A). This deficiency results in a progressive, multiorgan accumulation of glycolipids, most notably globotriaosylceramide (Gb3), leading to multiorgan failure and subsequently premature death. Gb3 accumulation in the podocytes, epithelial, and mesangial cells of the glomeruli results in progressive renal disease and eventually renal failure and hemodialysis (HD). There are two types of FD: early-onset classical type 1 and late-onset type 2. Although nearly a thousand mutations of the GLA gene have been identified, the majority of them are of unknown significance. Herein we report the case of a 25-year-old Caucasian male with no significant medical history who presented with peripheral neuropathy and end-stage renal failure, requiring HD. He was diagnosed with FD based on the electron microscopy findings of renal biopsy and severely reduced alpha-Gal A activity (<0.4 nmol/mL/hour). A novel mutation of c.281G>T; p.Cys94Phe was identified. On discharge from our facility, he was referred to a renal transplant center and genetic counseling.

Fabry cardiomyopathy: Gb3-induced auto-reactive panmyocarditis requiring heart transplantation

Resistance to enzyme replacement therapy (ERT) is a major therapeutic challenge in Fabry disease (FD). Recent reports attribute to immune‐mediated inflammation a main role in promoting disease progression and resistance to ERT. Aim of the study is to report a Gb3‐induced auto‐reactive panmyocarditis causing inefficacy of ERT and severe electrical instability, which required cardiac transplantation. Examining the explanted heart from a 57‐year‐old man with FD cardiomyopathy (CM) on 3‐year ERT presenting incoming ventricular fibrillation, we documented a severe virus‐negative myocarditis extended to cardiomyocytes, intramural coronary vessels, conduction tissue, and subepicardial ganglia. Serology was positive for anti‐Gb3, anti‐heart, and anti‐myosin antibodies. In vitro Gb3 stimulation of patient's peripheral blood mononuclear cells (PBMC) induced high amount production of inflammatory cytokine IL1‐β, IL‐6, IL‐8, and TNF‐α. PBMC were stained using the monoclonal antibodies CD3‐V500, CD4‐V450, CD8‐APCcy7, CD45RO‐PerCPcy5.5 and CD27‐FITC from BD Biosciences and CD56‐PC7 from Bekman Coulter. The phenotypic analysis of PBMC showed a lower frequency of CD8 (9.2%) vs. 19.3% and NKT cells (1.6% vs. 2.4%) in Fabry patient respect to healthy donor, suggesting a possible homing to peripheral tissues. A Gb3‐induced auto‐reactive myocarditis is suggested as a possible cause of FDCM progression and ERT resistance. Immune‐mediated inflammation of systemic Fabry cells may coexist and be controlled by implemental immunosuppressive therapy.

New drugs for the treatment of Anderson-Fabry disease

Enzyme replacement therapy (ERT) of the Anderson-Fabry disease (AFD) has changed the outcome of patients. However, ERT has some limitations: a restricted volume of distribution, requirement for intravenous access, and stimulation of the production of anti-drug antibodies. Studies of new drugs aiming to improve the clinical effectiveness and convenience of therapy have been reported. Migalastat, a pharmacological chaperone, increases available enzymate activity in patients with mutations amenable to the therapy, is now available for clinical practice. It is orally administered, and while clinical trial results are promising, long term real world follow up is awaited. PEGylated enzyme has a longer half-life and potentially reduced antigenicity, compared with standard preparations; investigation of whether a longer dosing interval is viable is under way. Moss-derived enzyme has a higher affinity for mannose receptors, and appears to have access to renal tissue. Substrate reduction therapy is based on reducing the catabolism processes of the glycosphingolipids, and is currently under investigation as monotherapy. Gene therapy has now been initiated in clinical trail of in vivo and ex vivo technologies with early results are emerging. ERT represents a certain milestone of therapy for AFD with Migalastat now a newly available option. Other agents in clinical trial prevent further potential opportunities to improve outcomes in AFD.

Fabry keratopathy: manifestations and changes over time

AIMS

The goal was to find if changes in Fabry keratopathy were clinically observable over time. Also observed were variations of Fabry keratopathy, supplemental features, unique presentations and differences between keratopathies of right and left corneas and the same family and genotype.

METHODS

Biomicroscopic images of Fabry keratopathy in 10 persons with classic Fabry disease, 5 men and 5 women, were captured over an 18-month period. The keratopathies were categorised and scrutinised for changes over time, and differences between corneas of the same individual, family and genotype.

RESULTS

Fabry keratopathy ranged from mild change to marked change over 18 months. There was a great variety of whorl patterns. A few keratopathies were amorphous without vortices and many vortices were supplemented with amorphous features. All keratopathies were accompanied by diffuse epithelial haze. There was a range from negligible difference to marked difference between right and left eyes of the same individuals with similarities appearing as imprecise mirror images of each other. In some corneas, prominent vertical streams from the superior limbus integrated into the primary keratopathy. Comparisons between persons with the same family and genotype were obscured by gender and differences between right and left eyes.

CONCLUSIONS

Practitioners should be better able to detect Fabry disease having a fuller understanding of the variety of presentations of the dynamic, pathognomonic Fabry keratopathy. Routes of continuous centripetal renewal of corneal epithelium are spatially unique to each eye, in some cases subsidised by direct contribution of basal cells streamed from the superior limbus.

Lysosomal storage disorders: pathology within the lysosome and beyond

This Preface introduces the articles of the special issue on "Lysosomal Storage Disorders" in which several recognized experts provide an overview of this research field. Lysosomes were first described in the 1950s and recognized for their role in substrate degradation and recycling. Because lysosomes impact numerous fundamental homeostatic processes, research on lysosomal storage disorders (LSDs) is crucial to advance our understanding of this intriguing organelle. This Special Issue highlights some of the LSDs that impact the central nervous system (CNS) as well as comprehensive overviews of lysosomal biology, CNS metabolism, and sphingolipid biosynthesis and turnover, all of which are critical toward our understanding of normal lysosomal function and how this is perturbed in the context of LSDs. This is the Preface for the special issue "Lysosomal Storage Disorders". Cover Image for this issue: doi: 10.1111/jnc.14496.

Systematic review of oral and craniofacial findings in patients with Fabry disease or Pompe disease

Fabry disease and Pompe disease are rare lysosomal storage disorders that belong to a heterogeneous group of more than 200 distinct inborn metabolic diseases. Mutations followed by loss of function of enzymes or transporters that are localised in the acidic environment of the lysosome may result in degradation of many substrates, such as glycosaminoglycans, glycosphingolipids, glycogen, cholesterol, oligosaccharides, glycoproteins, and peptides, or the excretion of the products degraded by the lysosome. Our aim was to identify the oral signs and symptoms of Fabry disease and Pompe disease from a systematic review made using MEDLINE/PubMed, and a hand search for relevant articles, following the PRISMA guidelines. Both diseases show various craniofacial and oral changes, including supernumerary teeth, dental agenesis, angiokeratoma, and telangiectases in Fabry disease; and macroglossia, teeth fusion, and taurodontism in Pompe disease. Common clinical signs of Fabry disease include hyposalivation, hypohidrosis, and xerophthalmia, and a generally reduced physical resilience was apparent in patients with Pompe disease. Oral and craniofacial changes in patients with both diseases extend over their entire lifetime and can be detected even in an infant. Lysosomal storage diseases should be taken into consideration in the differential diagnosis of relevant diverse symptoms, because treatment, when available, is most effective when started early. The main therapeutic concepts are enzymatic replacement for Pompe disease, whereas patients with Fabry disease require additional oral chaperone treatment or enzyme replacement.

Parapelvic cysts, a distinguishing feature of renal Fabry disease

Background

Fabry's disease (FD) is a rare, multi-organ lysosomal disease, caused by the deficiency of the enzyme α-galactosidase A, and is difficult to diagnose. Although parapelvic cysts (PC) were previously associated with FD, their prevalence and significance are unclear.

Methods

The present study aimed to: (i) evaluate, by renal ultrasound, the real prevalence of PC and of their determinants in a multicentre, nationwide cohort of FD patients (n = 173, Study 1) and (ii) ascertain whether a greater accuracy of PC detection improved their identification, in FD patients from a single centre (n = 67, Study 2). In both studies, for each FD patient, an age- and renal function-matched subject was selected for comparison (1:1).

Results

In Study 1, PC were detected in 28.9% of FD subjects and in only 1.1% of control subjects (P < 0.001). The presence of other renal abnormalities did not differ between the groups, nor differences exist in the main demographic and laboratory parameters between the groups. In Study 2, the greater accuracy of ultrasound increased PC prevalence from 29.8% to 43.3% in the same subjects (P < 0.05). In both studies, no correlation was detected between PC and the main demographic, clinical and biochemical parameters, including use of enzyme replacement therapy (P < 0.1, minimum value). Finally, no difference existed between FD patients with and without PC.

Conclusions

The present study suggests that the presence of PC in renal patients should alert physicians to consider the diagnosis of FD, primarily in subjects with an unclear family history of renal disease and in the presence of other stigmata of the disease.

Characterization of mesenchymal stem cells in mucolipidosis type II (I-cell disease)

Mucolipidosis type II (ML-II, I-cell disease) is a fatal inherited lysosomal storage disease caused by a deficiency of the enzyme N-acetylglucosamine-1-phosphotransferase. A characteristic skeletal phenotype is one of the many clinical manifestations of ML-II. Since the mechanisms underlying these skeletal defects in ML-II are not completely understood, we hypothesized that a defect in osteogenic differentiation of ML-II bone marrow mesenchymal stem cells (BM-MSCs) might be responsible for this skeletal phenotype. Here, we assessed and characterized the cellular phenotype of BM-MSCs from a ML-II patient before (BBMT) and after BM transplantation (ABMT), and we compared the results with BM-MSCs from a carrier and a healthy donor. Morphologically, we did not observe differences in ML-II BBMT and ABMT or carrier MSCs in terms of size or granularity. Osteogenic differentiation was not markedly affected by disease or carrier status. Adipogenic differentiation was increased in BBMT ML-II MSCs, but chondrogenic differentiation was decreased in both BBMT and ABMT ML-II MSCs. Immunophenotypically no significant differences were observed between the samples. Interestingly, the proliferative capacity of BBMT and ABMT ML-II MSCs was increased in comparison to MSCs from age-matched healthy donors. These data suggest that MSCs are not likely to cause the skeletal phenotype observed in ML-II, but they may contribute to the pathogenesis of ML-II as a result of lysosomal storage-induced pathology.

Pharmacokinetics, pharmacodynamics, and safety of moss-aGalactosidase A in patients with Fabry disease

Moss-aGalactosidase A (moss-aGal) is a moss-derived version of human α-galactosidase developed for enzyme replacement therapy in patients with Fabry disease. It exhibits a homogenous N-glycosylation profile with >90% mannose-terminated glycans. In contrast to mammalian cell produced α-galactosidase, moss-aGal does not rely on mannose-6-phosphate receptor mediated endocytosis but targets the mannose receptor for tissue uptake. We conducted a phase 1 clinical trial with moss-aGal in six patients with confirmed diagnosis of Fabry disease during a 28-day schedule. All patients received a single dose of 0.2 mg/kg moss-aGal by i.v.-infusion. Primary endpoints of the trial were safety and pharmacokinetics; secondary endpoints were pharmacodynamics by analyzing urine and plasma Gb3 and lyso-Gb3 concentrations. In all patients, the administered single dose was well tolerated. No safety issues were observed. Pharmacokinetic data revealed a stable nonlinear profile with a short plasma half-life of moss-aGal of 14 minutes. After one single dose of moss-aGal, urinary Gb3 concentrations decreased up to 23% 7 days and up to 60% 28 days post-dose. Plasma concentrations of lyso-Gb3 decreased by 3.8% and of Gb3 by 11% 28 days post-dose. These data reveal that a single dose of moss-aGal was safe, well tolerated, and led to a prolonged reduction of Gb3 excretion. As previously shown, moss-aGal is taken up via the mannose receptor, which is expressed on macrophages but also on endothelial and kidney cells. Thus, these data indicate that moss-aGal may target kidney cells. After these promising results, phase 2/3 clinical trials are in preparation.

Safety and effectiveness of enzyme replacement therapy with agalsidase alfa in patients with Fabry disease: Post-marketing surveillance in Japan

Fabry disease is a rare X-linked inherited multisystem disorder resulting from deficiency of the lysosomal enzyme alpha-galactosidase A. Currently, specific therapies, including enzyme replacement therapies, are available for Fabry disease, but clinical trials provide limited information on long-term safety and effectiveness. Agalsidase alfa was approved in Japan in 2006. The post-marketing surveillance study of all patients receiving agalsidase alfa to evaluate its long-term safety and effectiveness as a mandatory condition for its approval had been conducted for 8 years (from February 2007 to March 2015). A total of 493 patients were included in this analysis of safety and effectiveness. The overall mean follow-up period was 3.5 years (range, 0.0-7.9 years). The percentage of patients with adverse drug reactions was 24.5% (121/493) and 12.6% had infusion-related reactions (62/493). In the 256 patients without prior enzyme replacement therapy whose IgG antibody data were available, 17 were IgG antibody positive (6.6%). However, the chronological correlation between seroconversion and the incidence of infusion-related reactions was not clear. The mean brief pain inventory score of the worst pain decreased in patients with moderate and severe pain at baseline. Plasma Gb₃ and urine sediment Gb₃ in males with classical Fabry disease without prior enzyme replacement therapy significantly decreased. The mean yearly changes in eGFR (mL/min/1.73 m²) ranged from -2.88 to +1.00 in males with classical Fabry disease, from -2.04 to -0.95 in males with non-typical variant and from -2.64 to -1.02 in females. The lower eGFR or the more proteinuria at baseline, the faster the decrease in eGFR of the patients was observed. There was no substantial difference in cardiac parameters (left ventricular mass index, E/A wave ratio, ejection fraction, and QRS duration). In conclusion, agalsidase alfa, 0.2 mg/kg every other week, was well tolerated and controlled the progression of symptoms (especially renal and cardiac) of Fabry disease in adults. Enzyme replacement therapy should be started in Japanese patients before cardiac and/or renal symptoms of Fabry disease develop.

Improved Efficacy in a Fabry Disease Model Using a Systemic mRNA Liver Depot System as Compared to Enzyme Replacement Therapy

Fabry disease is a lysosomal storage disorder caused by the deficiency of α-galactosidase A. Enzyme deficiency results in a progressive decline in renal and cardiac function, leading to cardiomyopathy and end-stage renal disease. Current treatments available, including enzyme replacement therapies, have provided significant benefit to patients; however, unmet medical needs remain. mRNA therapy, with drug-like properties, has the unique ability to produce therapeutic proteins endogenously. Here we describe the sustained delivery of therapeutic human α-galactosidase protein in vivo via nanoparticle-formulated mRNA in mouse and non-human primate, with a demonstration of efficacy through clinically relevant biomarker reduction in a mouse Fabry disease model. Multi-component nanoparticles formulated with lipids and lipid-like materials were developed for the delivery of mRNA encoding human α-galactosidase protein. Upon delivery of human GLA mRNA to mice, serum GLA protein levels reached as high as ∼1,330-fold over normal physiological values.

Lysosome biogenesis in health and disease

This review focuses on the pathways that regulate lysosome biogenesis and that are implicated in numerous degenerative storage diseases, including lysosomal storage disorders and late-onset neurodegenerative diseases. Lysosomal proteins are synthesized in the endoplasmic reticulum and trafficked to the endolysosomal system through the secretory route. Several receptors have been characterized that execute post-Golgi trafficking of lysosomal proteins. Some of them recognize their cargo proteins based on specific amino acid signatures, others based on a particular glycan modification that is exclusively found on lysosomal proteins. Nearly all receptors serving lysosome biogenesis are under the transcriptional control of transcription factor EB (TFEB), a master regulator of the lysosomal system. TFEB coordinates the expression of lysosomal hydrolases, lysosomal membrane proteins, and autophagy proteins in response to pathways sensing lysosomal stress and the nutritional conditions of the cell among other stimuli. TFEB is primed for activation in lysosomal storage disorders but surprisingly its function is impaired in some late-onset neurodegenerative storage diseases like Alzheimer's and Parkinson's, because of specific detrimental interactions that limit TFEB expression or activation. Thus, disrupted TFEB function presumably plays a role in the pathogenesis of these diseases. Multiple studies in animal models of degenerative storage diseases have shown that exogenous expression of TFEB and pharmacological activation of endogenous TFEB attenuate disease phenotypes. These results highlight TFEB-mediated enhancement of lysosomal biogenesis and function as a candidate strategy to counteract the progression of these diseases. This article is part of the Special Issue "Lysosomal Storage Disorders".

Immune-Mediated Myocarditis in Fabry Disease Cardiomyopathy

Background Glycosphingolipid accumulation in Fabry cells generates a proinflammatory response that may influence disease evolution and responsiveness to enzyme replacement therapy. This study evaluated incidence, mechanism, and impact of myocarditis in Fabry disease cardiomyopathy ( FDCM ). Methods and Results Myocarditis, defined as CD 3+ T lymphocytes >7/mm2 associated with necrosis of glycolipid-laden myocardiocytes, was retrospectively evaluated in endomyocardial biopsies from 78 patients with FDCM : 13 with maximal wall thickness (MWT) <11 mm (group 1), 17 with MWT 11 to 15 mm (group 2), 30 with MWT 16 to 20 mm (group 3), and 18 with MWT >20 mm (group 4). Myocarditis was investigated by polymerase chain reaction for cardiotropic viruses, by serum antiheart and antimyosin antibodies, and by cardiac magnetic resonance. Myocarditis was recognized at histology in 48 of 78 patients with FDCM (38% of group 1, 41% of group 2, 66% of group 3, and 72% of group 4). Myocarditis was characterized by positive antiheart and antimyosin antibodies and negative polymerase chain reaction for viral genomes. CD 3+ cells/mm2 correlated with myocyte necrosis, antimyosin autoantibody titer, and MWT ( P<0.001, r=0.79; P<0.001, r=0.84; P<0.001, r=0.61, respectively). Cardiac magnetic resonance showed myocardial edema in 24 of 78 patients (31%): 0% of group 1, 23% of group 2, 37% of group 3, and 50% of group 4. Conclusions Myocarditis is detectable at histology in up to 56% of patients with FDCM . It is immune mediated and correlates with disease severity. It can be disclosed by antiheart/antimyosin autoantibodies and in the advanced phase by cardiac magnetic resonance. It may contribute to progression of FDCM and resistance to enzyme replacement therapy.

Serum Biomarkers of Endothelial Dysfunction in Fabry Associated Cardiomyopathy

Background: Fabry disease (FD) is characterized by early development of vasculopathy and endothelial dysfunction. However, it is unclear whether these findings also play a pivotal role in cardiac manifestation. As Fabry cardiomyopathy (FC) is the leading cause of death in FD, we aimed to gather a better insight in pathological mechanisms of the disease.

Methods: Serum samples were obtained from 17 healthy controls, 15 FD patients with and 7 without FC. FC was defined by LV wall thickening of >12 mm in cardiac magnetic resonance imaging and serum level of proBNP, high sensitive Troponin T (hsT), and globotriaosylsphingosine (lyso-GB3) were obtained. A multiplex ELISA-Assay for 23 different angiogenesis markers was performed in pooled samples. Markers showing significant differences among groups were further analyzed in single samples using specific Elisa antibody assays. L-homoarginine (hArg), L-arginine, asymmetric (ADMA), and symmetric Dimethylarginine (SDMA) were quantified by liquid chromatography—mass spectrometry.

Results: Angiostatin and matrix metalloproteinase 9 (MMP-9) were elevated in FD patients compared to controls independently of the presence of FC (angiostatin: 98 ± 25 vs. 75 ± 15 ng/mL; p = 0.001; MMP-9: 8.0 ± 3.4 vs. 5.0 ± 2.4 μg/mL; p = 0.002). SDMA concentrations were highest in patients with FC (0.90 ± 0.64 μmol/l) compared to patients without (0.57 ± 0.10 μmol/l; p = 0.027) and vs. controls (0.58 ± 0.12 μmol/l; p = 0.006) and was positively correlated with indexed LV-mass (r = 0.61; p = 0.003), hsT (r = 0.56, p = 0.008), and lyso-Gb3 (r = 0.53, p = 0.013). Accordingly, the ratio of L-homoarginine to SDMA (hArg/SDMA) was lowest in patients with FC (2.63 ± 1.78) compared to controls (4.16 ± 1.44; p = 0.005). For L-arginine, hArg and ADMA no significant differences among groups could be detected, although a trend toward higher ADMA and lower hArg levels could be observed in the FC group. Furthermore, a significant relationship between kidney and cardiac function could be revealed (p = 0.045).

Conclusion: Elevated MMP-9 and angiostatin levels suggest an increased extracellular matrix turnover in FD patients. Furthermore, endothelial dysfunction may also be involved in FC, as SDMA and hArg/SDMA are altered in these patients.

Inhibition of Arachidonate 12/15-Lipoxygenase Improves α-Galactosidase Efficacy in iPSC-Derived Cardiomyocytes from Fabry Patients

(1) Background: A high incidence of intervening sequence (IVS)4+919 G>A mutation with later-onset cardiac phenotype have been reported in a majority of Taiwan Fabry cohorts. Some evidence indicated that conventional biomarkers failed to predict the long-term progression and therapeutic outcome; (2) Methods: In this study, we constructed an induced pluripotent stem cell (iPSC)-based platform from Fabry cardiomyopathy (FC) patients carrying IVS4+919 G>A mutation to screen for potential targets that may help the conventional treatment; (3) Results: The FC-patient-derived iPSC-differentiated cardiomyocytes (FC-iPSC-CMs) carried an expected IVS4+919 G>A genetic mutation and recapitulated several FC characteristics, including low α-galactosidase A enzyme activity and cellular hypertrophy. The proteomic analysis revealed that arachidonate 12/15-lipoxygenase (Alox12/15) was the most highly upregulated marker in FC-iPSC-CMs, and the metabolites of Alox12/15, 12(S)- and 15(S)-hydroxyeicosatetraenoic acid (HETE), were also elevated in the culture media. Late administration of Alox12/15 pharmacological inhibitor LOXBlock-1 combined with α-galactosidase, but not α-galactosidase alone, effectively reduced cardiomyocyte hypertrophy, the secretion of 12(S)- and 15(S)-HETE and the upregulation of fibrotic markers at the late phase of FC; (4) Conclusions: Our study demonstrates that cardiac Alox12/15 and circulating 12(S)-HETE/15(S)-HETE are involved in the pathogenesis of FC with IVS4+919 G>A mutation.

Migalastat improves diarrhea in patients with Fabry disease: clinical-biomarker correlations from the phase 3 FACETS trial

Background

Fabry disease is frequently characterized by gastrointestinal symptoms, including diarrhea. Migalastat is an orally-administered small molecule approved to treat the symptoms of Fabry disease in patients with amenable mutations.

Methods

We evaluated minimal clinically important differences (MCID) in diarrhea based on the corresponding domain of the patient-reported Gastrointestinal Symptom Rating Scale (GSRS) in patients with Fabry disease and amenable mutations (N = 50) treated with migalastat 150 mg every other day or placebo during the phase 3 FACETS trial (NCT00925301).

Results

After 6 months, significantly more patients receiving migalastat versus placebo experienced improvement in diarrhea based on a MCID of 0.33 (43% vs 11%; p = .02), including the subset with baseline diarrhea (71% vs 20%; p = .02). A decline in kidney peritubular capillary globotriaosylceramide inclusions correlated with diarrhea improvement; patients with a reduction > 0.1 were 5.6 times more likely to have an improvement in diarrhea than those without (p = .031).

Conclusions

Migalastat was associated with a clinically meaningful improvement in diarrhea in patients with Fabry disease and amenable mutations. Reductions in kidney globotriaosylceramide may be a useful surrogate endpoint to predict clinical benefit with migalastat in patients with Fabry disease.

Trial registration

NCT00925301; June 19, 2009.

Import of TAT-Conjugated Propionyl Coenzyme A Carboxylase Using Models of Propionic Acidemia

Propionic acidemia is caused by a deficiency of the enzyme propionyl coenzyme A carboxylase (PCC) located in the mitochondrial matrix. Cell-penetrating peptides, including transactivator of transcription (TAT), offer a potential to deliver a cargo into the mitochondrion. Here, we investigated the delivery of an α₆β₆ PCC enzyme into mitochondria using the HIV TAT peptide at several levels: into isolated mitochondria, in patient fibroblast cells, and in a mouse model. Results from Western blots and enzyme activity assays confirmed the import of TAT-PCC into mitochondria, as well as into patient fibroblasts, where the colocalization of imported TAT-PCC and mitochondria was also confirmed by confocal fluorescence microscopy. Furthermore, a single-dose intraperitoneal injection into PCC-deficient mice decreased the propionylcarnitine/acetylcarnitine (C3/C2) ratio toward the normal level. These results show that a cell-penetrating peptide can deliver active multimeric enzyme into mitochondria in vitro, in situ, and in vivo and push the size limit of intracellular delivery achieved so far. Our results are promising for other mitochondrion-specific deficiencies.

Therapeutic Strategies Targeting Inherited Cardiomyopathies

PURPOSE OF REVIEW

Cardiomyopathies due to genetic mutations are a heterogeneous group of disorders that comprise diseases of contractility, myocardial relaxation, and arrhythmias. Our goal here is to discuss a limited list of genetically inherited cardiomyopathies and the specific therapeutic strategies used to treat them.

RECENT FINDINGS

Research into the molecular pathophysiology of the development of these cardiomyopathies is leading to the development of novel treatment approaches. Therapies targeting these specific mutations with gene therapy vectors are on the horizon, while other therapies which indirectly affect the physiologic derangements of the mutations are currently being studied and used clinically. Many of these therapies are older medications being given new roles such as mexiletine for Brugada syndrome and diflunisal for transthyretin amyloid cardiomyopathy. A newer targeted therapy, the inhibitor of myosin ATPase MYK-461, has been shown to suppress the development of ventricular hypertrophy, fibrosis, and myocyte disarray and is being studied as a potential therapy in patients with hypertrophic cardiomyopathy. While this field is too large to be completely contained in a single review, we present a large cross section of recent developments in the field of therapeutics for inherited cardiomyopathies. New therapies are on the horizon, and their development will likely result in improved outcomes for patients inflicted by these conditions.

In Vitro Study of Encapsulation Therapy for Fabry Disease Using Genetically Engineered CHO Cell Line

Fabry disease is an X-linked recessive disorder caused by a deficiency of the lysosomal hydrolase α-galac-tosidase A (α-gal). The deficiency of this enzyme leads to the systemic deposition of ceramide trihexoside (CTH) in various tissues and organs. Enzyme replacement using IV doses of recombinant human α-gal produced in CHO cells or in human fibroblasts is currently being evaluated in clinical trials as a potential therapy for this disease. However, it requires lifelong therapy involving a large amount of purified α-gal. As a novel approach for treatment of Fabry disease we used polymer encapsulated Chinese hamster ovary (CHO) cells genetically modified to express α-gal. The secreted high levels of α-gal passed through the semipermeable polymeric membrane. Using coculture system with Fabry fibroblasts, the secreted enzyme was taken up in cells, resulting in reduced accumulation of CTH in Fabry fibroblasts. This in vitro study demonstrated that an encapsulated α-gal-secreting cell line can be used to treat Fabry mice by transplantation in vivo. Judging from the protection against immune rejection by a semipermeable synthetic membrane, this novel approach may be applied to treat patients with Fabry disease and other lysosomal storage diseases.

Enzyme replacement therapy and beyond-in memoriam Roscoe O. Brady, M.D. (1923-2016)

Lysosomal storage disorders are strong candidates for the development of specific innovative therapies. The discovery of enzyme deficiencies is an important milestone in understanding the underlying cause of disease. Being able to replace the first missing enzyme in a lysosomal storage required three decades of dedicated research. Successful drug development for lysosomal storage disorders was fostered by the U.S. Orphan Drug Act. Various optimization strategies have the potential to overcome the current limitations of enzyme replacement therapies. In addition, substrate reduction therapies are an alternative approach to treat lysosomal storage disorders, chemical chaperones enhance residual enzyme activity, and small molecules can facilitate substrate transport through subcellular compartments. Bone-marrow derived multipotent stem cells and gene therapies have received FDA orphan drug designation status. The science of small clinical trials played an essential role: non-neurological endpoints, biomarker, and regulatory alignment are key factors in successful drug development for lysosomal storage disorders. Being able to treat brain disease is the next frontier. This review is dedicated to the memory of Roscoe O. Brady, an early pioneer in the research of lysosomal storage diseases.

Differences in cleavage of globotriaosylceramide and its derivatives accumulated in organs of young Fabry mice following enzyme replacement therapy

In Fabry disease, large amounts of globotriaosylceramide (Gb3) and related glycosphingolipids accumulate in organs due to a deficiency of α-galactosidase A (GLA) activity. Enzyme replacement therapy (ERT) with recombinant GLA is now available, and it has been reported that ERT is beneficial for patients with Fabry disease, especially those who start treatment at an early stage of the disease. However, it seems that the efficacy of ERT differs with each organ, and Gb3 accumulated in the kidneys shows resistance to ERT when it is started at a late stage. In this study, we examined the differences in cleavage of Gb3 isoforms, and lyso-Gb3 and its analogues in the kidneys, liver, and heart in young Fabry mice subjected to ERT. The results revealed that recurrent administration of recombinant GLA had prominent effects in terms of degradation of Gb3 and its derivatives accumulated in the organs. However, particular Gb3 isoforms, i.e., Gb3 (C20:0) and Gb3 (C24OH), accumulated in the kidneys largely escaped from degradation. Such Gb3 isoforms may gradually accumulate in the kidneys from a young age, which results in a reduction in the efficacy of ERT for Fabry disease.

A Preclinical Study Evaluating AAVrh10-Based Gene Therapy for Sanfilippo Syndrome

Mucopolysaccharidosis type IIIA (MPS IIIA) is predominantly a disorder of the central nervous system, caused by a deficiency of sulfamidase (SGSH) with subsequent storage of heparan sulfate-derived oligosaccharides. No widely available therapy exists, and for this reason, a mouse model has been utilized to carry out a preclinical assessment of the benefit of intraparenchymal administration of a gene vector (AAVrh10-SGSH-IRES-SUMF1) into presymptomatic MPS IIIA mice. The outcome has been assessed with time, measuring primary and secondary storage material, neuroinflammation, and intracellular inclusions, all of which appear as the disease progresses. The vector resulted in predominantly ipsilateral distribution of SGSH, with substantially less detected in the contralateral hemisphere. Vector-derived SGSH enzyme improved heparan sulfate catabolism, reduced microglial activation, and, after a time delay, ameliorated GM3 ganglioside accumulation and halted ubiquitin-positive lesion formation in regions local to, or connected by projections to, the injection site. Improvements were not observed in regions of the brain distant from, or lacking connections with, the injection site. Intraparenchymal gene vector administration therefore has therapeutic potential provided that multiple brain regions are targeted with vector, in order to achieve widespread enzyme distribution and correction of disease pathology.

Towards the development of an enzyme replacement therapy for the metabolic disorder propionic acidemia

Propionic acidemia (PA) is a life-threatening disease caused by the deficiency of a mitochondrial biotin-dependent enzyme known as propionyl coenzyme-A carboxylase (PCC). This enzyme is responsible for degrading the metabolic intermediate, propionyl coenzyme-A (PP-CoA), derived from multiple metabolic pathways. Currently, except for drastic surgical and dietary intervention that can only provide partial symptomatic relief, no other form of therapeutic option is available for this genetic disorder. Here, we examine a novel approach in protein delivery by specifically targeting and localizing our protein candidate of interest into the mitochondrial matrix of the cells. In order to test this concept of delivery, we have utilized cell penetrating peptides (CPPs) and mitochondria targeting sequences (MTS) to form specific fusion PCC protein, capable of translocating and localizing across cell membranes. In vitro delivery of our candidate fusion proteins, evaluated by confocal images and enzymatic activity assay, indicated effectiveness of this strategy. Therefore, it holds immense potential in creating a new paradigm in site-specific protein delivery and enzyme replacement therapeutic for PA.

[Treatment of Fabry disease: Successes, failures, and expectations]

Fabry disease, an X-linked lysosomal storage disease, results from α-galactosidase A deficiency. Two different recombinant enzyme treatments (algalsidase alpha agalsidase beta) have been available since 2001 to treat a disease that affects not only men but also women. Enzyme replacement therapy promotes cell clearance of susbtrate, and improves some clinical parameters (heart, kidney damage, pain, quality of life). However, there is no proven efficacy to date on central nervous system lesions, on cardiac morbidity and mortality, nor on renal damage beyond a certain stage (proteinuria>1g/day and/or estimated glomerular filtration rate<60mL/min/1.73m(2)). In this review, we discuss the potential benefit of an early intervention, the vascular protective measures to be associated with enzyme therapy and their rationale, and some alternative treatments under development, such as chaperones and substrate molecules inhibitors.

Mannose receptor-mediated delivery of moss-made α-galactosidase A efficiently corrects enzyme deficiency in Fabry mice

Enzyme replacement therapy (ERT) is an effective treatment for several lysosomal storage disorders (LSDs). Intravenously infused enzymes are taken up by tissues through either the mannose 6-phosphate receptor (M6PR) or the mannose receptor (MR). It is generally believed that M6PR-mediated endocytosis is a key mechanism for ERT in treating LSDs that affect the non-macrophage cells of visceral organs. However, the therapeutic efficacy of MR-mediated delivery of mannose-terminated enzymes in these diseases has not been fully evaluated. We tested the effectiveness of a non-phosphorylated α-galactosidase A produced from moss (referred to as moss-aGal) in vitro and in a mouse model of Fabry disease. Endocytosis of moss-aGal was MR-dependent. Compared to agalsidase alfa, a phosphorylated form of α-galactosidase A, moss-aGal was more preferentially targeted to the kidney. Cellular localization of moss-aGal and agalsidase alfa in the heart and kidney was essentially identical. A single injection of moss-aGal led to clearance of accumulated substrate in the heart and kidney to an extent comparable to that achieved by agalsidase alfa. This study suggested that mannose-terminated enzymes may be sufficiently effective for some LSDs in which non-macrophage cells are affected, and that M6P residues may not always be a prerequisite for ERT as previously considered.

Anderson-Fabry cardiomyopathy: prevalence, pathophysiology, diagnosis and treatment

Anderson-Fabry disease (AFD) is a lysosomal storage disease caused by the inappropriate accumulation of globotriaosylceramide in tissues due to a deficiency in the enzyme α-galactosidase A (α-Gal A). Anderson-Fabry cardiomyopathy is characterized by structural, valvular, vascular and conduction abnormalities, and is now the most common cause of mortality in patients with AFD. Large-scale metabolic and genetic screening studies have revealed AFD to be prevalent in populations of diverse ethnic origins, and the variant form of AFD represents an unrecognized health burden. Anderson-Fabry disease is an X-linked disorder, and genetic testing is critical for the diagnosis of AFD in women. Echocardiography with strain imaging and cardiac magnetic resonance imaging using late enhancement and T1 mapping are important imaging tools. The current therapy for AFD is enzyme replacement therapy (ERT), which can reverse or prevent AFD progression, while gene therapy and the use of molecular chaperones represent promising novel therapies for AFD. Anderson-Fabry cardiomyopathy is an important and potentially reversible cause of heart failure that involves LVH, increased susceptibility to arrhythmias and valvular regurgitation. Genetic testing and cardiac MRI are important diagnostic tools, and AFD cardiomyopathy is treatable if ERT is introduced early.

A prospective 10-year study of individualized, intensified enzyme replacement therapy in advanced Fabry disease

OBJECTIVES

To test the hypothesis that more frequent enzyme replacement therapy (ERT) slows the decline in kidney function in adult patients with Fabry disease.

METHODS

A single center open label 10-year prospective clinical trial of 12 patients with advanced Fabry disease who, after having experienced an ongoing decline in renal function after 2-4 years of receiving ERT at the approved dose of 0.2 mg/kg agalsidase alfa every other week (EOW), were switched to weekly (EW) ERT at the same dose. We used linear regression to fit each individual patient's longitudinal estimated glomerular filtration rate (eGFR) record in order to compare the deterioration rates between EOW and EW ERT.

RESULTS

For the entire group, mean slope on agalsidase alfa every 2 weeks was -7.92 ± 2.88 ml/min/1.73 m(2)/year and 3.84 ± 4.08 ml/min/1.73 m(2)/year on weekly enzyme infusions (p = 0.01, two-tailed paired t test). Three patients (25 %) completed the entire study with relatively preserved renal function while 50 % of patients reached end-stage renal disease (ESRD) during the 10 years of this study. The estimated average delay to ESRD was 13.8 years [n = 11; 95 % CI 0.66, 27]. One patient had a positive eGFR slope on weekly infusions while the patient with the highest antibody titer had a steeper slope after switching. Mean globotriaosylceramide concentrations in urine and plasma as well as urine protein excretion remained unchanged.

CONCLUSIONS

Weekly enzyme infusions slow the decline of renal function in a subgroup of more severe patients thus showing that existing ERT can be further optimized.

Reduction of Plasma Globotriaosylsphingosine Levels After Switching from Agalsidase Alfa to Agalsidase Beta as Enzyme Replacement Therapy for Fabry Disease

INTRODUCTION

Agalsidase alfa and agalsidase beta, recombinant enzyme preparations for treatment of Fabry disease (FD), have different approved dosing schedules: 0.2 mg/kg and 1.0 mg/kg every other week (EOW), respectively.

METHODS

This open-label, multicenter, exploratory phase 4 study evaluated plasma globotriaosylsphingosine (lyso-GL-3) and plasma and urine globotriaosylceramide (GL-3) levels at baseline and 2, 4, and 6 months after the switch from agalsidase alfa (0.2 mg/kg EOW for ≥12 months) to agalsidase beta (1.0 mg/kg EOW) in 15 male patients with FD. Immunoglobulin (Ig)G antidrug antibody titers were assessed, and safety was monitored throughout the study.

RESULTS

Plasma lyso-GL-3 concentrations decreased significantly within 2 months after switch and reductions continued through month 6 (mean absolute changes, -12.8, -16.1, and -16.7 ng/mL at 2, 4, and 6 months, respectively; all P < 0.001). The mean percentage reduction from baseline was 39.5% (P < 0.001) at month 6. For plasma GL-3, the mean absolute change from baseline (-0.9 μg/mL) and percentage reduction (17.9%) at month 6 were both significant (P < 0.05). Urine GL-3 measurements showed intra-patient variability and changes from baseline were not significant. No clinical outcomes were assessed in this 6-month study, and, therefore, no conclusions can be drawn regarding the correlation of observed reductions in glycosphingolipid concentrations with clinically relevant outcomes. There were no differences in IgG antidrug antibody titers between the two enzymes. The switch from agalsidase alfa to agalsidase beta was well tolerated.

CONCLUSION

Plasma lyso-GL-3 and GL-3 levels reduced after switching from agalsidase alfa to agalsidase beta, indicating that agalsidase beta has a greater pharmacodynamic effect on these markers at the recommended dose. These data further support the use of agalsidase beta 1.0 mg/kg EOW as enzyme replacement therapy in FD.