Clinical results of enzyme replacement therapy in Fabry disease: a comprehensive review of literature

Anti-drug antibody formation in Japanese Fabry patients following enzyme replacement therapy

Enzyme replacement therapy (ERT) for Fabry disease (deficiency of α-galactosidase A, α-Gal) with recombinant α-Gals (agalsidase alfa and agalsidase beta) is widely available and improves some of the clinical manifestations and biochemical findings. However, recent reports suggest that recurrent administration of recombinant enzymes often induces the formation of anti-drug antibodies, which may have a negative impact on the outcome of the therapy. We examined the formation of anti-drug antibodies using blood samples from 97 Japanese Fabry patients following ERT and tried to characterize them by means of enzyme-linked immunosorbent assay (ELISA), serum-mediated α-Gal inhibition, and immunochromatographic (IC) assay, followed by GLA gene analysis and measurement of plasma globotriaosylsphingosine (lyso-Gb3). ELISA revealed that 20/35 (57%) classic Fabry males were antibody (Immunoglobulin G, IgG) -positive (Ab+) at 6 months after the initiation of ERT, although only two of the seventeen (12%) later-onset Fabry males and none of the 45 Fabry females were. The Ab+ state was maintained at least until 24 months after the initiation of ERT in most of the cases, the exceptions being two patients who acquired immune tolerance during ERT. As many Ab+ patients have nonsense mutations, attention should be paid to the formation of anti-drug antibodies in Fabry patients harboring such gene mutations, who hardly produce α-Gal protein. Serum-mediated α-Gal inhibition was seen in most of the Ab+ patients and the antibodies affected the reduction of the plasma lyso-Gb3 level following ERT, suggesting that the antibodies inhibit the enzyme activity. There was a correlation between the results of the IC test and those of the ELISA. As the former is easy and rapid, it should be useful as a bed-side test.

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The anti-drug antibodies formed in Fabry patients during ERT were characterized.

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Serum-mediated α-Gal inhibition was seen in most of the antibody-positive patients.

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The immunochromatographic test is easy, rapid, and useful as a bed-side test.

Ocular findings in Fabry disease in Colombian patients

Fabry disease is a rare X-linked disorder caused by an alpha-galactosidase enzyme deficiency, which leads to a progressive lysosomal glycosphingolipids accumulation, mainly globotriaosylceramide, in multiple organism tissues including the eye.This case series describes the first ophthalmological Colombian report of Fabry disease highlighting the importance of ocular signs as markers of the disease, useful in diagnosis and treatment to avoid long-term complications that lead to a morbi-mortality increment.We describe five cases of Fabry disease from Bogotá, Colombia, including a complete clinical history, ophthalmologic, optometric examination, and photographs. We found that all patients had refractive defects and that in all cases corneal verticillata pattern was found. Four patients presented with posterior capsule lens brown-beige deposits and four patients had conjunctival and retinal tortuous vessels. A complete ophthalmologic examination is important for prompt diagnosis, which is key to starting a multidisciplinary treatment and reducing morbi-mortality.

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.

Drug discovery and development for rare genetic disorders

Approximately 7,000 rare diseases affect millions of individuals in the United States. Although rare diseases taken together have an enormous impact, there is a significant gap between basic research and clinical interventions. Opportunities now exist to accelerate drug development for the treatment of rare diseases. Disease foundations and research centers worldwide focus on better understanding rare disorders. Here, the state-of-the-art drug discovery strategies for small molecules and biological approaches for orphan diseases are reviewed. Rare diseases are usually genetic diseases; hence, employing pharmacogenetics to develop treatments and using whole genome sequencing to identify the etiologies for such diseases are appropriate strategies to exploit. Beginning with high throughput screening of small molecules, the benefits and challenges of target-based and phenotypic screens are discussed. Explanations and examples of drug repurposing are given; drug repurposing as an approach to quickly move programs to clinical trials is evaluated. Consideration is given to the category of biologics which include gene therapy, recombinant proteins, and autologous transplants. Disease models, including animal models and induced pluripotent stem cells (iPSCs) derived from patients, are surveyed. Finally, the role of biomarkers in drug discovery and development, as well as clinical trials, is elucidated.

Carbohydrate-Processing Enzymes of the Lysosome: Diseases Caused by Misfolded Mutants and Sugar Mimetics as Correcting Pharmacological Chaperones

Lysosomal storage diseases are hereditary disorders caused by mutations on genes encoding for one of the more than fifty lysosomal enzymes involved in the highly ordered degradation cascades of glycans, glycoconjugates, and other complex biomolecules in the lysosome. Several of these metabolic disorders are associated with the absence or the lack of activity of carbohydrate-processing enzymes in this cell compartment. In a recently introduced therapy concept, for susceptible mutants, small substrate-related molecules (so-called pharmacological chaperones), such as reversible inhibitors of these enzymes, may serve as templates for the correct folding and transport of the respective protein mutant, thus improving its concentration and, consequently, its enzymatic activity in the lysosome. Carbohydrate-processing enzymes in the lysosome, related lysosomal diseases, and the scope and limitations of reported reversible inhibitors as pharmacological chaperones are discussed with a view to possibly extending and improving research efforts in this area of orphan diseases.

Glycosphingolipid storage in Fabry mice extends beyond globotriaosylceramide and is affected by ABCB1 depletion

Aim:

Fabry disease is caused by α-galactosidase A deficiency leading to accumulation of globotriaosylceramide (Gb₃) in tissues. Clinical manifestations do not appear to correlate with total Gb₃ levels. Studies examining tissue distribution of specific acyl chain species of Gb₃ and upstream glycosphingolipids are lacking.

Material & methods/Results:

Thorough characterization of the Fabry mouse sphingolipid profile by LC-MS revealed unique Gb₃ acyl chain storage profiles. Storage extended beyond Gb₃; all Fabry tissues also accumulated monohexosylceramides. Depletion of ABCB1 had a complex effect on glycosphingolipid storage.

Conclusion:

These data provide insights into how specific sphingolipid species correlate with one another and how these correlations change in the α-galactosidase A-deficient state, potentially leading to the identification of more specific biomarkers of Fabry disease.

Fabry disease is caused by a shortage of the enzyme α-galactosidase A leading to storage of a fat called globotriaosylceramide (Gb₃) in tissues. Disease severity does not appear to correlate directly with total Gb₃. Importantly, Gb₃ is comprised of many highly related but distinct species. We examined levels of Gb₃ species and precursor molecules in Fabry mice. Gb₃ species and storage are unique to each tissue. Furthermore, storage is not limited to Gb₃; precursor fats are also elevated. Detailed analyses of differences in storage between the normal and α-galactosidase A-deficient state may provide a better understanding of the causes of Fabry disease.

Enzyme Replacement Therapy in Patients with Fabry's Disease

Fabry's disease, a disorder affecting the gene for the lysosomal enzyme α-galactosidase A (α-GAL A), can cause accumulation of globotriaosylceramide (GL-3) in the vascular endothelial cells. Symptoms include pain, angiokeratoma, corneal clouding, and damage to the heart and kidneys. Human recombinant α-GAL A for use as an enzyme replacement therapy was launched in Japan in April 2004. Eleven ambulatory patients with Fabry's disease were given replacement α-GAL A therapy. Three patients died due to factors associated with Fabry's disease. The enzyme replacement therapies in the remaining eight patients continued safely without any notable adverse events. The following were observed: a lowering of the plasma levels of GL-3 in seven cases, an improvement in the daily activities in six cases, and a reduction in corneal clouding in three cases. Although careful observation is necessary, these results suggest that replacement α-GAL A therapy may be a safe and effective treatment of Fabry's disease.

Ocular signs correlate well with disease severity and genotype in Fabry disease

Ocular signs in Fabry disease have generally been regarded to be primarily of diagnostic value. We explored whether ocular findings, alone or in particular in combination with the α-galactosidase A gene mutation, have predictive value for disease severity. Data from the Fabry Outcome Survey (FOS), a large, global database sponsored by Shire, were selected for adult patients who had undergone ophthalmological examination. Three ocular signs were assessed: cornea verticillata, tortuous conjunctival and/or retinal vessels, and cataract. Fabry disease severity was measured using FOS Mainz Severity Score Index and modifications thereof. Ophthalmological data were available for 1203 (699 female, 504 male) adult patients with eye findings characteristic of Fabry disease in 55.1%. Cornea verticillata had a similar distribution in women (51.1%) and men (50.8%), whereas tortuous vessels and Fabry cataract were somewhat more frequent in men than in women. Patients with cornea verticillata, selected as the principal ocular sign for this study, had more severe disease (median score, 20.0) versus those without ocular signs (11.0; P<0.001). This finding could be confirmed by applying age adjusted severity scores. Moreover, the prevalence of cornea verticillata was significantly higher in patients with null (male, 76.9%; female, 64.5%) and missense (male, 79.2%; female, 67.4%) mutations versus mild missense (male, 17.1%; female, 23.1%) and the p.N215S (male, 15.0%; female, 15.6%) mutations (P<0.01). Our analyses show a correlation between the prevalence of ocular changes in Fabry disease and disease severity. Consequently, information on ocular findings and α-galactosidase A gene mutation may help assess the risk for more severe Fabry disease. These observed findings are of notable clinical importance, as Fabry disease is characterized by high clinical course variability and only weak genotype-phenotype correlation at the individual patient level. Further confirmatory studies are needed.

Gene therapy for neurologic manifestations of mucopolysaccharidoses

INTRODUCTION

Mucopolysaccharidoses (MPS) are a family of lysosomal disorders caused by mutations in genes that encode enzymes involved in the catabolism of glycoaminoglycans. These mutations affect multiple organ systems and can be particularly deleterious to the nervous system. At the present time, enzyme replacement therapy and hematopoietic stem-cell therapy are used to treat patients with different forms of these disorders. However, to a great extent, the nervous system is not adequately responsive to current therapeutic approaches.

AREAS COVERED

Recent advances in gene therapy show great promise for treating MPS. This article reviews the current state of the art for routes of delivery in developing genetic therapies for treating the neurologic manifestations of MPS.

EXPERT OPINION

Gene therapy for treating neurological manifestations of MPS can be achieved by intraventricular, intrathecal, intranasal and systemic administrations. The intraventricular route of administration appears to provide the most widespread distribution of gene therapy vectors to the brain. The intrathecal route of delivery results in predominant distribution to the caudal areas of the brain. The systemic route of delivery via intravenous infusion can also achieve widespread delivery to the CNS; however, the distribution to the brain is greatly dependent on the vector system. Intravenous delivery using lentiviral vectors appear to be less effective than adeno-associated viral (AAV) vectors. Moreover, some subtypes of AAV vectors are more effective than others in crossing the blood-brain barrier. In summary, the recent advances in gene vector technology and routes of delivery to the CNS will facilitate the clinical translation of gene therapy for the treatment of the neurological manifestations of MPS.

Kidney function as an underestimated factor for reduced health related quality of life in patients with Fabry disease

Background

Impairments of health related quality of life (HRQoL) are frequently observed in Fabry disease (FD) and are known to be related to neuropathic pain and cardiovascular events. This study aimed to explore the role of chronic kidney disease (CKD) in a large cohort of patients with FD.

Methods

In 96 patients (53% female; age 40 ± 12 yrs) with genetically proven FD, HRQoL was assessed by the Medical Outcomes Study (SF-36) questionnaire. All patients were naïve to enzyme replacement therapy. Three categories for kidney dysfunction were chosen, eGFR ≥/<60 ml/min/1.73 m² or need of renal replacement therapy (RRT). Minor (e.g. arrhythmia, angina pectoris, etc.) and major (e.g. myocardial infarction, coronary artery bypass, stroke or implantable cardioverter-defibrillator) vascular events as well as pain and pain therapy were considered in linear regression analyses with the dimensions of HRQoL.

Results

Ten patients (10%) had impaired kidney function and a further nine were on RRT (9.4%). Kidney function and pain emerged as the main factors associated with lower scores on the SF 36, in particular on physical components (PCS beta-coefficients for CKD −6.2, for RRT −11.8, for pain −9.1, p < 0.05, respectively), while controlling for gender, vascular event and pain-therapy. Relationships were found for mental aspects of HRQoL. Age and history of vascular events were not related to HRQoL.

Conclusion

Cardiovascular events and pain are important factors related to HRQoL, social functioning and depression. Our study highlights impaired chronic kidney disease, in particular after initiation of RRT, as a strong determinant of reduced HRQoL in FD.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2369-15-188) contains supplementary material, which is available to authorized users.

Fabry nephropathy: a review - how can we optimize the management of Fabry nephropathy?

Fabry disease is a rare, X-linked, lysosomal storage disease caused by mutations in the gene encoding the enzyme alpha-galactosidase A. Complete or partial deficiency in this enzyme leads to intracellular accumulation of globotriaosylceramide (Gb₃) and related glycosphingolipids in many cell types throughout the body, including the kidney. Progressive accumulation of Gb₃ in podocytes, epithelial cells and the tubular cells of the distal tubule and loop of Henle contribute to the renal symptoms of Fabry disease, which manifest as proteinuria and reduced glomerular filtration rate leading to chronic kidney disease and progression to end-stage renal disease. Early diagnosis and timely initiation of treatment of Fabry renal disease is an important facet of disease management. Initiating treatment with enzyme replacement therapy (ERT; agalsidase alfa, Replagal^®, Shire; agalsidase beta, Fabrazyme^®, Genzyme) as part of a comprehensive strategy to prevent complications of the disease, may be beneficial in stabilizing renal function or slowing its decline. Early initiation of ERT may also be more effective than initiating therapy in patients with more advanced disease. Several strategies are required to complement the use of ERT and treat the myriad of associated symptoms and organ involvements. In particular, patients with renal Fabry disease are at risk of cardiovascular events, such as high blood pressure, cardiac arrhythmias and stroke. This review discusses the management of renal involvement in Fabry disease, including diagnosis, treatments, and follow-up, and explores recent advances in the use of biomarkers to assist with diagnosis, monitoring disease progression and response to treatment.

Successful management of enzyme replacement therapy in related fabry disease patients with severe adverse events by switching from agalsidase Beta (fabrazyme(®)) to agalsidase alfa (replagal (®))

BACKGROUND

Enzyme replacement therapy (ERT) is the only approved therapy for Fabry disease. In June 2009, there was a worldwide shortage of agalsidase beta, necessitating dose reductions or switching to agalsidase alfa in some patients.

CASE PRESENTATION

We present two cases of Fabry disease (a parent and a child) who received agalsidase beta for 27 months at the licensed dose and 10 months at a reduced dose, followed by a switch to agalsidase alfa for 28 months. Case 1, a 26-year-old male had severe coughing and fatigue during ERT with agalsidase beta requiring antitussive and asthmatic drug therapy. After switching to agalsidase alfa, the coughing gradually resolved completely. Case 2, a 62-year-old female had advanced cardiac manifestations at the time of diagnosis. Despite receiving ERT with the approved dose of agalsidase beta, she experienced aggravation of congestive heart failure and was hospitalized. After switching to agalsidase alfa with standard care in heart disease, BNP level, echocardiographic parameters, eGFR rate and lyso-Gb3 levels were improved or stabilized.

CONCLUSIONS

We report on two Fabry disease patients who experienced severe adverse events while on approved and/or reduced doses of agalsidase beta. Switching to agalsidase alfa associated with standard care in heart disease led to resolution or improvement in the cardiorespiratory status. And reduction in dose associated with standard care in respiratory disease was useful for decrease in cough and fatigue. Plasma BNP level was useful for monitoring heart failure and the effects of ERT.

Enzyme replacement therapy for Fabry disease: A systematic review and meta-analysis

The specific treatment available for Fabry disease (FD) is enzyme replacement therapy (ERT) with agalsidase alfa or beta. A systematic review and meta-analysis was conducted to assess the efficacy and safety of ERT for FD. Only double-blind, randomized clinical trials (RCTs) comparing agalsidase alfa or beta and placebo were included. ERT with either agalsidase alfa or beta was considered similar for the purposes of analysis. Ten RCTs were identified, which showed improvements in neuropathic pain, in heart abnormalities and in globotriaosylceramide (GL-3) levels. A meta-analysis showed increased odds for fever, rigors, development of IgG antibodies to agalsidase, and no significant association with development of hypertension or reduction in the QRS complex duration on electrocardiogram. The RCTs included in this comparison enrolled few patients, were highly heterogeneous, and were focused mainly on surrogate endpoints, limiting any conclusions as to the real effect of ERT for FD. The available evidence suggests that response to ERT is variable across patient subgroups and that agalsidase may slow progression of FD, with slight improvement of existing changes. Nevertheless, many uncertainties remain, and further studies are necessary.

Enzyme replacement therapy in patients with Fabry disease: state of the art and review of the literature

Anderson-Fabry disease is an X-linked lysosomal storage disorder resulting from the deficiency of the hydrolytic enzyme alpha galactosidase A, with consequent accumulation of globotrioasoyl ceramide in cells and tissues of the body, resulting in a multi-system pathology including end organ failure. In the classical phenotype, cardiac failure, renal failure and stroke result in a reduced median life expectancy. The current causal treatment for Fabry disease is the enzyme replacement therapy (ERT): two different products, Replagal (agalsidase alfa) and Fabrazyme (agalsidase beta), have been commercially available in Europe for almost 10 years and they are both indicated for long-term treatment. In fact, clinical trials, observational studies and registry data have provided many evidences for safety and efficacy of ERT in improving symptoms of pain, gastrointestinal disturbances, hypohidrosis, left ventricular mass index, glomerular filtration rate and quality of life. Few data are available on comparison of the two treatments and on the clinical course of the disease. This article reviews the published evidence for clinical efficacy of the two available enzyme preparations.

Clinical observation of patients with Fabry disease after switching from agalsidase beta (Fabrazyme) to agalsidase alfa (Replagal)

PURPOSE

Fabry disease is a rare, X-linked, inherited lysosomal storage disorder that can be treated with the enzymes agalsidase alfa (Replagal) and agalsidase beta (Fabrazyme). Currently, there is a global shortage of agalsidase beta, and this has increased global demand for agalsidase alfa. We assess the feasibility of switching patients on agalsidase beta treatment to agalsidase alfa instead.

METHODS

This analysis is part of an ongoing observational study involving 11 patients with Fabry disease in whom the treatment was switched from agalsidase beta (1 mg/kg every other week) to agalsidase alfa (0.2 mg/kg every other week). Data were collected for a minimum of 36 months: 24 months before and 12 months after the switch. Serial data were evaluated with respect to renal function, cardiac mass, pain, quality of life, and tolerability/safety.

RESULTS

Indexes of renal function (estimated glomerular filtration rate) and cardiac mass (left-ventricular mass index), pain (Brief Pain Inventory), and quality of life (EuroQoL-Dimensions) clearly showed that, in patients switched to agalsidase alfa, Fabry disease stabilized during the 12 months of follow-up.

CONCLUSION

Despite the limitations of this preliminary observational study, it was found that all the patients maintained disease stability when treated with agalsidase alfa, as evidenced by estimated glomerular filtration rate, left-ventricular mass index, pain scores, and quality-of-life indexes, throughout 12 months of follow-up.

Lentivector transduction improves outcomes over transplantation of human HSCs alone in NOD/SCID/Fabry mice

Fabry disease is a lysosomal storage disorder caused by a deficiency of α-galactosidase A (α-gal A) activity that results in progressive globotriaosylceramide (Gb(3)) deposition. We created a fully congenic nonobese diabetic (NOD)/severe combined immunodeficiency (SCID)/Fabry murine line to facilitate the in vivo assessment of human cell-directed therapies for Fabry disease. This pure line was generated after 11 generations of backcrosses and was found, as expected, to have a reduced immune compartment and background α-gal A activity. Next, we transplanted normal human CD34(+) cells transduced with a control (lentiviral vector-enhanced green fluorescent protein (LV-eGFP)) or a therapeutic bicistronic LV (LV-α-gal A/internal ribosome entry site (IRES)/hCD25). While both experimental groups showed similar engraftment levels, only the therapeutic group displayed a significant increase in plasma α-gal A activity. Gb(3) quantification at 12 weeks revealed metabolic correction in the spleen, lung, and liver for both groups. Importantly, only in the therapeutically-transduced cohort was a significant Gb(3) reduction found in the heart and kidney, key target organs for the amelioration of Fabry disease in humans.

Modelling the resource implications of managing adults with Fabry disease in Italy

AIMS

This study estimated the resource implications and budget impact of managing adults with Fabry disease in Italy, from the perspective of the Servizio Sanitario Nazionale (SSN).

METHODS

A decision model was constructed using published clinical outcomes and clinician-derived resource utilisation estimates depicting the management of adults with Fabry disease in Italy.

RESULTS

The expected annual cost of managing 220 existing and 20 new Fabry patients in Italy was estimated to be €28·3 million. In an average year, patients receiving enzyme replacement therapy (ERT) with 0·2 mg kg(-1) agalsidase alfa (Replagal; Shire Human Genetic Therapies, Basingstoke, Hampshire, UK) or 1·0 mg kg(-1) agalsidase beta (Fabrazyme; Genzyme Europe BV, Naarden, The Netherlands) are collectively expected to make 4500 hospital attendances to a day ward for infusions, which equates to 2000 eight-h days on the day ward associated with ERT. If all ERT-treated patients received their infusions at home, there would be a marginal reduction in the annual health care cost to manage these patients, and the total annual number of days on the day ward associated with ERT in the second year could potentially be reduced from a mean 2000 to zero, thereby releasing substantial hospital resources for use by non-Fabry patients. Currently, only agalsidase alfa is licensed for home treatment in Italy; hence, only patients receiving this enzyme could be offered home treatment.

CONCLUSION

Use of agalsidase alfa (0·2 mg kg(-1) ) instead of agalsidase beta (1·0 mg kg(-1)) has the potential to reduce health care costs and release hospital resources in different specialities for alternative use by non-Fabry patients, thereby improving the efficiency of the public health care system in Italy.

Update on role of agalsidase alfa in management of Fabry disease

Fabry disease (FD) is an X-linked lysosomal storage disorder that affects both men and women. The manifestations of this heterogeneous disease are multisystemic and progressive. Prior to the development of enzyme replacement therapy, the management and treatment for Fabry disease was largely nonspecific and supportive. Because enzyme replacement therapy became commercially available in 2001, a variety of clinical benefits in Fabry patients have been consistently reported, including improved renal pathology and cardiac function, and reduced severity of neuropathic pain and improved pain-related quality of life. This update focuses on published data on the efficacy and tolerability of enzyme replacement therapy with agalsidase alfa, and gives a brief overview on some of the outstanding management issues in the treatment of this complex disease.

High throughput screening for inhibitors of alpha-galactosidase

Fabry disease is a rare X-linked lysosomal storage disorder caused by a deficiency in α-galactosidase A (GLA), which catalyzes the hydrolysis of terminal α-galactosyl groups from glycosphingolipids, such as globotriaosylceramide (Gb3). Many of the mutations in the GLA gene are missense alterations that cause misfolding, decreased stability, and/or mistrafficking of this protein. Small molecule compounds that correct the misfolding and mistrafficking, or activate the mutant enzyme, may be useful in the treatment of Fabry disease. We have screened a library of approximately 230,000 compounds using preparations of human recombinant protein and purified coffee bean enzyme in an effort to find activators and inhibitors of this enzyme. Lansoprazole was identified as a small molecule inhibitor of GLA derived from coffee beans (IC₅₀ = 6.4 μM), but no inhibitors or activators were identified for the human enzyme. The screening results indicate that human GLA is a difficult target for small molecule inhibition or activation.

Enzyme replacement therapy in a patient with Fabry disease and the development of IgE antibodies against agalsidase beta but not agalsidase alpha

Fabry disease is an X-linked inherited lysosomal storage disorder caused by an inborn deficiency of the enzyme α-galactosidase A. Enzyme replacement therapy (ERT) with agalsidase alpha or beta isozymes is an effective treatment. Cross-reactivity of immunoglobulin G (IgG) antibodies with agalsidase alpha and beta has been reported, but no such reaction has been recorded for IgE antibodies. We present the case of a patient with Fabry disease who developed antiagalsidase beta IgE antibodies without cross-reactivity to agalsidase alpha. A 17-year-old boy with Fabry disease had suffered from severe atopic dermatitis since infancy, and he complained for several years of peripheral pain during the summer months and when exercising. Fabry disease was confirmed by family history and a positive enzyme test, and ERT was commenced. Following infusion of agalsidase beta (1.0 mg/kg), the patient complained of a high temperature in his hands and feet, and purulent eczema developed. The infusion dose was reduced to 0.2 mg/kg, but the hyperthermia did not change, although its duration decreased. After three infusions, eosinophilia developed (9.4%; 573 cells/μl blood) and remained unresolved after four infusions with agalsidase beta. Treatment with this enzyme was discontinued, and agalsidase alpha (0.2 mg/kg) started. This produced immediate resolution of the eosinophilia, which has been maintained during follow-up. In conclusion, this patient developed IgE antibodies against agalsidase beta, which demonstrated no cross-reactivity to agalsidase alpha. These findings emphasize the importance of analyzing IgE antibodies against both enzymes when patients exhibit severe infusion-related events.

Modelling the resource implications of managing adults with Fabry disease in Norway favours home infusion

BACKGROUND

The aim of this study was to estimate the resource implications and budget impact of managing adults with Fabry disease in Norway, from the perspective of the publicly funded healthcare system.

METHODS

A decision model was constructed using published clinical outcomes and clinician-derived resource utilization estimates. The model was used to estimate the annual healthcare cost of managing a cohort of 64 adult Fabry patients in an average year.

RESULTS

The expected annual cost of managing 60 existing Fabry patients and four new patients in Norway each year was estimated to be NOK 55·8 million (€6·7 million). In an average year, patients receiving enzyme replacement therapy (ERT) with agalsidase alfa (Replagal(®)) at 0·2 mg kg⁻¹ or agalsidase beta (Fabrazyme(®)) at 1·0 mg kg⁻¹ are collectively expected to make 586 attendances to their family practitioner's office for their infusions, which equates to 128 eight-hour days associated with ERT. Encouraging more patients to undergo home-based infusions has substantial potential to free-up community-based resources. In comparison, the community-related benefit that can be obtained by switching from agalsidase beta (1·0 mg kg⁻¹) to agalsidase alpha (0·2 mg kg⁻¹) is marginal, and dependent on the two doses being clinically equivalent.

CONCLUSION

Maximizing the proportion of adults with Fabry disease undergoing home-based infusions has the potential to release community-based resources for alternative use by non-Fabry patients, thereby improving the efficiency of the publicly funded healthcare system in Norway.

Substrate reduction augments the efficacy of enzyme therapy in a mouse model of Fabry disease

Fabry disease is an X-linked glycosphingolipid storage disorder caused by a deficiency in the activity of the lysosomal hydrolase α-galactosidase A (α-gal). This deficiency results in accumulation of the glycosphingolipid globotriaosylceramide (GL-3) in lysosomes. Endothelial cell storage of GL-3 frequently leads to kidney dysfunction, cardiac and cerebrovascular disease. The current treatment for Fabry disease is through infusions of recombinant α-gal (enzyme-replacement therapy; ERT). Although ERT can markedly reduce the lysosomal burden of GL-3 in endothelial cells, variability is seen in the clearance from several other cell types. This suggests that alternative and adjuvant therapies may be desirable. Use of glucosylceramide synthase inhibitors to abate the biosynthesis of glycosphingolipids (substrate reduction therapy, SRT) has been shown to be effective at reducing substrate levels in the related glycosphingolipidosis, Gaucher disease. Here, we show that such an inhibitor (eliglustat tartrate, Genz-112638) was effective at lowering GL-3 accumulation in a mouse model of Fabry disease. Relative efficacy of SRT and ERT at reducing GL-3 levels in Fabry mouse tissues differed with SRT being more effective in the kidney, and ERT more efficacious in the heart and liver. Combination therapy with ERT and SRT provided the most complete clearance of GL-3 from all the tissues. Furthermore, treatment normalized urine volume and uromodulin levels and significantly delayed the loss of a nociceptive response. The differential efficacies of SRT and ERT in the different tissues indicate that the combination approach is both additive and complementary suggesting the possibility of an improved therapeutic paradigm in the management of Fabry disease.

Early initiation of enzyme replacement therapy improves metabolic correction in the brain tissue of aspartylglycosaminuria mice

Aspartylglycosaminuria (AGU) is a lysosomal storage disease caused by deficient activity of glycosylasparaginase (AGA), and characterized by motor and mental retardation. Enzyme replacement therapy (ERT) in adult AGU mice with AGA removes the accumulating substance aspartylglucosamine from and reverses pathology in many somatic tissues, but has only limited efficacy in the brain tissue of the animals. In the current work, ERT of AGU mice was initiated at the age of 1 week with three different dosage schedules of recombinant glycosylasparaginase. The animals received either 3.4 U of AGA/kg every second day for 2 weeks (Group 1), 1.7 U/kg every second day for 9 days followed by an enzyme injection once a week for 4 weeks (Group 2) or 17 U/kg at the age of 7 and 9 days (Group 3). In the Group 1 and Group 3 mice, ERT reduced the amount of aspartylglucosamine by 34 and 41% in the brain tissue, respectively. No therapeutic effect was observed in the brain tissue of Group 2 mice. As in the case of adult AGU mice, the AGA therapy was much more effective in the somatic tissues than in the brain tissue of the newborn AGU mice. The combined evidence demonstrates that a high dose ERT with AGA in newborn AGU mice is up to twofold more effective in reducing the amount of the accumulated storage material from the brain tissue than ERT in adult AGU animals, indicating the importance of early detection and treatment of the disease.

Management of Fabry disease

A Fabry-kór a lizoszomális tárolási betegségek csoportjába tartozó, X-kromoszómához kötötten, recesszív módon öröklődő betegség, amely a globotriaozilceramid felhalmozódásához vezet a szervezet legkülönbözőbb szöveteiben. A betegség első tünetei többnyire gyermekkorban jelentkeznek, a progresszió során a betegek súlyos szervi károsodásokkal és korai halálozással számolhatnak. Elsősorban férfiak érintettek, azonban a betegség tüneteit heterozigóta nők esetében is megfigyelhetjük, de náluk a kórkép súlyossága változó, általában enyhébb lefolyású. Az enzimpótló kezelések megjelenése szükségessé tette, hogy részletes diagnosztikus és terápiás protokollt dolgozzunk ki. A jelen dolgozatban megjelenő ajánlásokat egy, a magyarországi Fabry-kóros betegek kezelésében részt vevő orvosokból, a diagnosztika területén dolgozó biológosukból és egyéb szakemberekből álló multidiszciplináris munkacsoport foglalta össze. A munkacsoport áttekintette a korábbi klinikai tanulmányokat, a publikált vizsgálatokat és a közelmúltban megjelent nemzetközi és nemzeti útmutatókat.

Fabry disease - current treatment and new drug development

Fabry disease is a rare inherited lysosomal storage disorder caused by a partial or complete deficiency of α-galactosidase A (GLA), resulting in the storage of excess cellular glycosphingolipids. Enzyme replacement therapy is available for the treatment of Fabry disease, but it is a costly, intravenous treatment. Alternative therapeutic approaches, including small molecule chaperone therapy, are currently being explored. High throughput screening (HTS) technologies can be utilized to discover other small molecule compounds, including non-inhibitory chaperones, enzyme activators, molecules that reduce GLA substrate, and molecules that activate GLA gene promoters. This review outlines the current therapeutic approaches, emerging treatment strategies, and the process of drug discovery and development for Fabry disease.

Nervous system and Fabry disease, from symptoms to diagnosis: damage evaluation and follow-up in adult patients, enzyme replacement, and support therapy

The X-linked genetic Fabry disease causes multiorgan lesions due to intracellular storage of the substrate globotriaosylceramide. Neurological involvement ranges from painful, small fiber neuropathy to cerebrovascular disorders to multifocal aggressive forms. Disease identification through proper differential diagnosis and timely assessment of organ damage should guide a careful treatment planning. Mainstay treatment, include enzyme replacement and support therapy. Neurologists have a pivotal role in early instrumental and clinical detection of organ damage. A panel of experts has developed a set of consensus recommendations to guide the approach of neurologists to Fabry disease.

Multi-system disorders of glycosphingolipid and ganglioside metabolism

Glycosphingolipids (GSLs) and gangliosides are a group of bioactive glycolipids that include cerebrosides, globosides, and gangliosides. These lipids play major roles in signal transduction, cell adhesion, modulating growth factor/hormone receptor, antigen recognition, and protein trafficking. Specific genetic defects in lysosomal hydrolases disrupt normal GSL and ganglioside metabolism leading to their excess accumulation in cellular compartments, particularly in the lysosome, i.e., lysosomal storage diseases (LSDs). The storage diseases of GSLs and gangliosides affect all organ systems, but the central nervous system (CNS) is primarily involved in many. Current treatments can attenuate the visceral disease, but the management of CNS involvement remains an unmet medical need. Early interventions that alter the CNS disease have shown promise in delaying neurologic involvement in several CNS LSDs. Consequently, effective treatment for such devastating inherited diseases requires an understanding of the early developmental and pathological mechanisms of GSL and ganglioside flux (synthesis and degradation) that underlie the CNS diseases. These are the focus of this review.

The use of agalsidase alfa enzyme replacement therapy in the treatment of Fabry disease

BACKGROUND

Fabry disease is an X-linked lysosomal storage disease caused by deficiency of alpha-galactosidase A (alpha-Gal A), encoded by the GLA gene. The deficiency causes accumulation of neutral glycosphingolipids in various tissues, leading to neuronopathic pain, progressive renal dysfunction, cardiomyopathy and stroke. Enzyme replacement therapy (ERT) with agalsidase alfa (Replagal, Shire Human Genetic Therapies) is approved for use by 40 countries, but not the US.

OBJECTIVE

To evaluate agalsidase alfa in therapy of Fabry disease.

METHODS

An examination of relevant reports.

RESULTS/CONCLUSIONS

Clinical trials data, along with experience of the treatment collected through participation of treating physicians in a world-wide Fabry disease registry, have demonstrated that it improves pain and stabilizes renal function, as well as cardiomyopathy, in some patients. More data are needed to evaluate the role of treatment with this drug in the prevention of stroke and adverse cardiac events, and its overall effect on the lifespan and quality of life of affected individuals.

Fabry disease urinary globotriaosylceramide/creatinine biomarker evaluation by liquid chromatography-tandem mass spectrometry in healthy infants from birth to 6 months

Fabry disease is an X-linked lysosomal storage disorder caused by deficiency of alpha-galactosidase A, resulting in accumulation of the principal substrate, globotriaosylceramide (Gb(3)), in various physiological fluids and tissues in affected patients. The recognition that accumulation of Gb(3) begins in utero, combined with the fact that the diagnosis of the disease is often delayed until after the development of irreversible tissue damage, has generated pressure to develop techniques for the early, pre-symptomatic diagnosis of the disease. Measurements of urinary Gb(3) have been shown to be useful for the diagnosis of Fabry disease in adults. The objective of this work was to measure the Gb(3)/creatinine biomarker in urine of healthy infants from birth to 6 months, including the establishment of reference ranges for urinary Gb(3) excretion at various postnatal ages, in male and female infants. We employed liquid chromatography-tandem mass spectrometry (LC-MS/MS) to determine Gb(3)/creatinine ratios in urine specimens dried on filter paper and mailed to the laboratory by participating parents. A total of 728 urine specimens were obtained at intervals from birth to 6 months of age from 68 healthy infants (35 male and 33 female). Parental participation was good, with 90% of the expected specimens received by the laboratory. The results of the analyses were grouped by the age of the infants into four periods. We have determined that both postnatal age and sex have an effect on urinary Gb(3) excretion levels which vary considerably in newborns. We conclude that screening for Fabry disease by measurement of urinary Gb(3) excretion is unlikely to be reliable before 30 days of age.

Synthesis and characterization of a new fluorogenic substrate for alpha-galactosidase

Alpha-galactosidase A hydrolyzes the terminal alpha-galactosyl moieties from glycolipids and glycoproteins in lysosomes. Mutations in alpha-galactosidase cause lysosomal accumulation of the glycosphingolipid, globotriaosylceramide, which leads to Fabry disease. Small-molecule chaperones that bind to mutant enzyme proteins and correct their misfolding and mistrafficking have emerged as a potential therapy for Fabry disease. We have synthesized a red fluorogenic substrate, resorufinyl alpha-D-galactopyranoside, for a new alpha-galactosidase enzyme assay. This assay can be measured continuously at lower pH values, without the addition of a stop solution, due to the relatively low pK(a) of resorufin (approximately 6). In addition, the assay emits red fluorescence, which can significantly reduce interferences due to compound fluorescence and dust/lint as compared to blue fluorescence. Therefore, this new red fluorogenic substrate and the resulting enzyme assay can be used in high-throughput screening to identify small-molecule chaperones for Fabry disease.

Kidney transplantation in patients with Fabry disease

Little is known about the effects of enzyme replacement therapy (ERT) in kidney transplant recipients with Fabry disease. Clinical characteristics of transplant recipients in the Fabry Outcome Survey (FOS) were therefore examined in patients with Fabry disease with or without ERT. Of the 837 European patients in FOS (March 2006), 34 male patients and two female patients had received kidney transplants. Mean age at transplantation was 37.6 +/- 10.9 years, mean time since transplantation was 7.7 +/- 6.4 years, median estimated glomerular filtration rate (eGFR) was 44.4 ml/min/1.73 m(2), and median proteinuria was 296 mg/24 h. Of 27 patients with baseline data, 59% had hypertension, 74% had left ventricular hypertrophy, 22% had cardiac valve disease, 30% had arrhythmia, and 22% had transient ischaemic attacks and 15% stroke. Twenty patients (74%; two female patients, 18 male patients) were receiving ERT with agalsidase alfa. At enrollment or at the start of ERT, median eGFRs were 59 and 35 ml/min/1.73 m(2) (P = 0.05) and median proteinuria levels were 240 and 420 mg/24 h (not significant) in treated and untreated patients respectively. Renal function remained stable in patients receiving ERT. In conclusion, agalsidase alfa is well tolerated in patients with Fabry disease who have undergone renal transplantation.

Fabry's disease

Fabry's disease is an X-linked lysosomal storage disorder caused by abnormalities in the GLA gene, which leads to a deficiency in alpha-galactosidase A. The consequent abnormal accumulation of glycosphingolipids results in several clinical signs and symptoms and substantial morbidity and mortality. This review covers all basic aspects of the disease such as epidemiology, pathophysiology, clinical presentation by systems, diagnosis, management, prevention, and repercussions on quality of life. With the development of enzyme replacement therapy in the past few years, early initiation of treatment is key for improvement in major affected organs with decreased cardiac mass and stabilisation of kidney function, and improvement in neuropathic pain, sweating, gastrointestinal symptoms, hearing loss, and pulmonary symptoms. However, treatment of individual symptoms in addition to enzyme replacement therapy seems to be needed for many patients, especially those who have had some degree of organ dysfunction. Additional data are needed to document long-term treatment outcomes.