Effects of enzyme replacement therapy in adult patients with Fabry disease on cardiac structure and function: a retrospective cohort study of the Fabry Munster Study (FaMuS) data

Cardiac involvement in Fabry disease - A non-invasive assessment and the role of specific therapies

Fabry disease is an X-linked inherited metabolic disorder due to the pathogenic mutation of the GLA gene, which codes lysosomal enzyme alpha-galactosidase A. The resultant accumulation of glycosphingolipids causes various systemic symptoms in childhood and adolescence, and major organ damage in adulthood. Cardiac involvement is important as the most frequent cause of death in Fabry disease patients. Progressive left ventricular hypertrophy with varying degrees of contractile dysfunction as well as conduction abnormalities and arrhythmias are typical cardiac features, and these findings can be evaluated in detail via non-invasive modalities, such as an electrocardiogram, echocardiography and cardiac magnetic resonance. In addition, specific therapies of enzyme replacement therapy and pharmacological chaperone therapy are available, and their beneficial effects on cardiac involvement have been reported. This minireview highlights recent evidence concerning non-invasive modalities for assessing cardiac involvement in Fabry disease and the effects of enzyme replacement therapy and pharmacological chaperone therapy on the findings of those modalities.

The Role of Cardiac Imaging in the Diagnosis and Management of Anderson-Fabry Disease

Anderson-Fabry disease (AFD) is a rare X-linked inherited metabolic disorder which results in a deficiency or absence of the enzyme α-galactosidase A, leading to the accumulation of glycosphingolipids in various cells and organs including the heart. Cardiac involvement is common and results in increased myocardial inflammation, left ventricular hypertrophy (LVH), and myocardial fibrosis. Echocardiography and cardiovascular magnetic resonance (CMR) offer distinctive and often complementary use to assist in the diagnosis and monitoring pharmacologic therapy in AFD, including detection of the AFD cardiac phenotype, differentiation from other forms of LVH, and patient selection for therapeutic intervention. Advanced cardiac imaging holds promise in subclinical detection of AFD-related abnormalities as well as disease staging and prognostication.

The effect of enzyme replacement therapy on clinical outcomes in male patients with Fabry disease: A systematic literature review by a European panel of experts

BACKGROUND

Enzyme replacement therapy (ERT) with recombinant human α-galactosidase has been available for the treatment of Fabry disease since 2001 in Europe and 2003 in the USA. Treatment outcomes with ERT are dependent on baseline patient characteristics, and published data are derived from heterogeneous study populations.

METHODS

We conducted a comprehensive systematic literature review of all original articles on ERT in the treatment of Fabry disease published up until January 2017. This article presents the findings in adult male patients.

RESULTS

Clinical evidence for the efficacy of ERT in adult male patients was available from 166 publications including 36 clinical trial publications. ERT significantly decreases globotriaosylceramide levels in plasma, urine, and in different kidney, heart, and skin cell types, slows the decline in estimated glomerular filtration rate, and reduces/stabilizes left ventricular mass and cardiac wall thickness. ERT also improves nervous system, gastrointestinal, pain, and quality of life outcomes.

CONCLUSIONS

ERT is a disease-specific treatment for patients with Fabry disease that may provide clinical benefits on several outcomes and organ systems. Better outcomes may be observed when treatment is started at an early age prior to the development of organ damage such as chronic kidney disease or cardiac fibrosis. Consolidated evidence suggests a dose effect. Data described in male patients, together with female and paediatric data, informs clinical practice and therapeutic goals for individualized treatment.

Effectiveness of enzyme replacement therapy in Fabry disease: Long term experience in Argentina

Evidence regarding long term effectiveness of enzyme replacement therapy (ERT) in Fabry disease (FD) is needed. The aim of this study was to analyze in a cohort of FD patients in Argentina, the long term effectiveness of ERT on renal, cardiac and cerebrovascular parameters.

Methods

Patients with genetically proven FD were included from GADYTEF (Argentinean group for the treatment of FD) between 2001 and 2014. Renal, cardiac, and cerebral outcomes were prospectively studied in patients treated with ERT. Additionally, the occurrence of major cardiac complications, stroke, end-stage renal disease and death was analyzed during follow up.

Results

During the follow-up 8 major complications occurred in 5 patients (n = 2 deaths, n = 4 cases of end stage renal disease and n = 1 atrial fibrillation), 4 of them males and only 1 female who suffered an atrial fibrillation. Sudden death or stroke did not occur. Four (40%) of 10 males with baseline left ventricular hypertrophy (LVH) reduced left ventricular mass index (LVMI) from 163.1 ± 64.7 to 123.4 ± 49.8 g/m², 2 stabilized LVMI and 4 increased LVMI from157.9 ± 32.3 to 261.6 ± 48.6 g/m². Estimated glomerular filtration was stable in 30 patients (17 males and 13 females).

Conclusions

We observed a few major complications during the follow up. Future studies are necessary to show the effectiveness of ERT in affected patients.

Oral pharmacological chaperone migalastat compared with enzyme replacement therapy in Fabry disease: 18-month results from the randomised phase III ATTRACT study

Background

Fabry disease is an X-linked lysosomal storage disorder caused by GLA mutations, resulting in α-galactosidase (α-Gal) deficiency and accumulation of lysosomal substrates. Migalastat, an oral pharmacological chaperone being developed as an alternative to intravenous enzyme replacement therapy (ERT), stabilises specific mutant (amenable) forms of α-Gal to facilitate normal lysosomal trafficking.

Methods

The main objective of the 18-month, randomised, active-controlled ATTRACT study was to assess the effects of migalastat on renal function in patients with Fabry disease previously treated with ERT. Effects on heart, disease substrate, patient-reported outcomes (PROs) and safety were also assessed.

Results

Fifty-seven adults (56% female) receiving ERT (88% had multiorgan disease) were randomised (1.5:1), based on a preliminary cell-based assay of responsiveness to migalastat, to receive 18 months open-label migalastat or remain on ERT. Four patients had non-amenable mutant forms of α-Gal based on the validated cell-based assay conducted after treatment initiation and were excluded from primary efficacy analyses only. Migalastat and ERT had similar effects on renal function. Left ventricular mass index decreased significantly with migalastat treatment (−6.6 g/m² (−11.0 to −2.2)); there was no significant change with ERT. Predefined renal, cardiac or cerebrovascular events occurred in 29% and 44% of patients in the migalastat and ERT groups, respectively. Plasma globotriaosylsphingosine remained low and stable following the switch from ERT to migalastat. PROs were comparable between groups. Migalastat was generally safe and well tolerated.

Conclusions

Migalastat offers promise as a first-in-class oral monotherapy alternative treatment to intravenous ERT for patients with Fabry disease and amenable mutations.

Trial registration number:

NCT00925301; Pre-results.

Innate and Adaptive Immune Response in Fabry Disease

Fabry disease is an X-linked lysosomal storage disease in which mutations of the gene (GLA) cause a deficiency of the lysosomal hydrolase α-galactosidase A (α-Gal). This defect results in an accumulation of glycosphingolipids, primarily globotriaosylceramide (Gb3) which causes a multisystemic vasculopathy. Available since 2001 in Europe, enzyme replacement therapy consists in the administration of agalsidase, a recombinant form of α-galactosidase A. Enzyme replacement therapy was shown to improve the global prognosis but allowed partial success in preventing critical events such as strokes and cardiac arrests. As in most lysosomal storage diseases, frequent immune reactions have been described in naive Fabry disease patients. Humoral immune responses following enzyme replacement therapy have also been described, with unclear consequences on the progression of the disease. While cost-effectiveness of enzyme replacement therapy in Fabry disease begins to be questioned and new therapeutic strategies arise such as chaperone or gene therapy, it appears necessary to better understand the immune responses observed in the treatment of naive patients and during enzyme replacement therapy with agalsidase. We propose a comprehensive review of the available literature concerning both innate and adaptive responses observed in Fabry disease. We particularly highlight the probable role of the toll-like receptor 4 (TLR4) and CD1d pathways triggered by Gb3 accumulation in the development of local and systemic inflammation that could lead to irreversible organ damages. We propose an immunological point of view of Fabry disease pathogenesis involving immune cells notably the invariant natural killer T cells. We finally review anti-agalsidase antibodies, their development and impact on outcomes.

Characterization of a chemically modified plant cell culture expressed human α-Galactosidase-A enzyme for treatment of Fabry disease

Fabry disease is an X-linked recessive disorder caused by the loss of function of the lysosomal enzyme α-Galactosidase-A. Although two enzyme replacement therapies (ERTs) are commercially available, they may not effectively reverse some of the Fabry pathology. PRX-102 is a novel enzyme for the therapy of Fabry disease expressed in a BY2 Tobacco cell culture. PRX-102 is chemically modified, resulting in a cross-linked homo-dimer. We have characterized the in-vitro and in-vivo properties of PRX-102 and compared the results with the two commercially produced α-Galactosidase-A enzymes. Results show that PRX-102 has prolonged in-vitro stability in plasma, after 1h incubation it retains 30% activity compared with complete inactivation of the commercial enzymes. Under lysosomal-like conditions PRX-102 maintains over 80% activity following 10 days of incubation, while commercial enzymes become inactive after 2days. Pharmacokinetic profile of PRX-102 measured in male Fabry mice shows a 10 fold increase in t1/2 in mice (581min) compared to approved drugs. The enzyme has significantly different kinetic parameters to the alternative ERTs available (p-value<0.05, one way ANOVA), although these differences do not indicate any significant biochemical variations. PRX-102 is uptaken to primary human Fabry fibroblasts. The repeat administration of the enzyme to Fabry mice caused significant reduction (p-value<0.05) of Gb3 in various tissues (the measured residual content was 64% in kidney, liver was cleaned, 23% in heart, 5.7% in skin and 16.2% in spleen). PRX-102 has a relatively simple glycosylation pattern, characteristic to plants, having mainly tri-mannose structures with the addition of either α(1-3)-linked fucose or β(1-2)-linked xylose, or both, in addition to various high mannose structures, while agalsidase beta has a mixture of sialylated glycans in addition to high mannose structures. This study concludes that PRX-102 is equivalent in functionality to the current ERTs available, with superior stability and prolonged circulatory half-life. Therefore we propose that PRX-102 is a promising alternative for treatment of Fabry disease.

Myocardial fibrosis as the first sign of cardiac involvement in a male patient with Fabry disease: report of a clinical case and discussion on the utility of the magnetic resonance in Fabry pathology

BACKGROUND

Cardiovascular magnetic resonance (CMR) with late gadolinium enhancement (LGE) imaging is increasingly used to assess myocardial involvement in patients with Fabry disease, an X linked lipid storage disorder. However, it is often proposed as an optional tool. A different cardiomyopathic disease progression between male and female patients was hypothesised in previous studies, as in female myocardial fibrosis was found without left ventricular (LV) hypertrophy, while myocardial fibrosis was always detected in association to LV hypertrophy in men.

CASE PRESENTATION

A male Caucasian patient, 19 years old, diagnosed through a family-based molecular screening, presented with LGE of the LV inferolateral wall evidenced at the CMR, without LV hypertrophy, or other clinical signs of the disease.

CONCLUSION

This is the first report of cardiac fibrosis as the first sign of organ involvement in a male patient with Fabry disease. This finding stresses the importance of performing CMR with LGE imaging for the initial staging and monitoring of Fabry patients of both genders.

Natural course of Fabry disease and the effectiveness of enzyme replacement therapy: a systematic review and meta-analysis: effectiveness of ERT in different disease stages

OBJECTIVE

Current available evidence on long-term effectiveness of enzyme replacement therapy (ERT) for Fabry disease is limited. More insight is needed whether ERT effectiveness differs in patients with and without baseline end-organ damage.

DESIGN

Through a systematic review, untreated and ERT treated males and females with Fabry disease were compared for main clinical outcomes: renal function, left ventricular mass (LVmass), cerebral white matter lesions (WMLs) and end-organ complications. Through a meta-analysis ERT effectiveness was estimated in different disease stages.

DATA EXTRACTION

Two reviewers assessed quality of the included studies according to guidelines for prognosis research. Data were synthesized using a random effects meta-analysis.

RESULTS

Thirty-one studies were systematically reviewed while six studies were included in the meta-analysis. In patients with a GFR > 60 ml/min/1.73 m(2), decline of renal function was similar for treated and untreated patients. Only ERT treated males with a GFR < 60 ml/min/1.73 m(2) had a slower rate of decline in renal function, possibly attributable to anti-proteinuric therapy. Regardless of left ventricular hypertrophy (LVH) at baseline, LVmass remained stable or increased in males despite ERT, however at a slower rate compared to untreated male patients. In ERT treated females with LVH LVmass decreased, and remained stable in females without LVH. WMLs can not be prevented by ERT. Stroke, cardiac and end-stage renal complications develop, though the incidence of new complications seems to be reduced during ERT.

CONCLUSION

ERT is effective in reducing LVH, but has a limited effect on renal function. Improved treatment options are needed for Fabry disease.