Agalsidase Alfa: A Review of its Use in the Management of Fabry Disease

Enzyme therapy: a forerunner in catalyzing a healthy society?

INTRODUCTION

The use of enzymes in various industries has been prevalent for centuries. However, their potency as therapeutics remained latent until the late 1950 s, when scientists finally realized the gold mine they were sitting on. Enzyme therapy has seen rapid development over the past few decades and has been widely used for the therapy of myriad diseases, including lysosomal storage disorders, cancer, Alzheimer's disease, irritable bowel syndrome, exocrine pancreatic insufficiency, and hyperuricemia. Enzymes are also used for wound healing, the treatment of microbial infections, and gene therapy.

AREAS COVERED

This is a comprehensive review of the therapeutic use of enzymes that can act as a guidepost for researchers and academicians and presents a general overview of the developments in enzyme therapy over the years, along with updates on recent advancements in enzyme therapy research.

EXPERT OPINION

Although enzyme therapy is immensely beneficial and induces little auxiliary damage, it has several drawbacks, ranging from high cost, low stability, low production, and hyperimmune responses to the failure to cure a variety of the problems associated with a disease. Further fine-tuning and additional clinical efficacy studies are required to establish enzyme therapy as a forerunner to catalyzing a healthy society.

Effect and Tolerability of Agalsidase Alfa in Patients with Fabry Disease Who Were Treatment Naïve or Formerly Treated with Agalsidase Beta or Agalsidase Alfa

OBJECTIVES

In a multicenter, open-label, treatment protocol (HGT-REP-059; NCT01031173), clinical effects and tolerability of agalsidase alfa (agalα; 0.2 mg/kg every other week) were evaluated in patients with Fabry disease who were treatment naïve or switched from agalsidase beta (switch). Over 24 months, data were collected on the safety profile; renal and cardiac parameters were assessed using estimated glomerular filtration rate (eGFR), left ventricular mass index (LVMI), and midwall fractional shortening (MFS).

RESULTS

Enrolled patients included 71 switch (median [range] age, 46.6 [5-84] years; male to female [M:F], 40:31) and 29 treatment naïve (38.7 [12-74] years; M:F, 14:15). Adverse events (AEs) were consistent with the known safety profile of agalα. Two switch patients had hospitalization due to possibly/probably drug-related serious AEs (one with transient ischemic attack, one with infusion-related AEs). One switch and two treatment-naïve patients discontinued treatment because of AEs. Three patients (one each switch, treatment naïve, and previous agalα) died; no deaths were considered drug-related. There was no significant change from baseline in LVMI or MFS in either group. Similarly, eGFR remained stable; mean ± standard error annualized change in eGFR (mL/min/1.73 m(2)) was -2.40 ± 1.04 in switch and -1.68 ± 2.21 in treatment-naïve patients.

CONCLUSIONS

This is the largest cohort of patients with Fabry disease who were started on or switched to agalα in an FDA-accepted protocol during a worldwide supply shortage of agalsidase beta. Because this protocol was primarily designed to provide access to agalα, there were limitations, including not having stringent selection criteria and the lack of a placebo group.

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.

Comparison of intracellular and secretion-based strategies for production of human α-galactosidase A in the filamentous fungus Trichoderma reesei

BACKGROUND

Trichoderma reesei is known as a good producer of industrial proteins but has hitherto been less successful in the production of therapeutic proteins. In order to elucidate the bottlenecks of heterologous protein production, human α-galactosidase A (GLA) was chosen as a model therapeutic protein. Fusion partners were designed to compare the effects of secretion using a cellobiohydrolase I (CBHI) carrier and intracellular production using a gamma zein peptide from maize (ZERA) which accumulates inside the endoplasmic reticulum (ER). The two strategies were compared on the basis of expression levels, purification performance, enzymatic activity, bioreactor cultivations, and transcriptional profiling.

RESULTS

Constructs were cloned into the cbh1 locus of the T. reesei strain Rut-C30. The secretion and intracellular strains produced 20 mg/l and 636 mg/l of GLA respectively. Purifications of secreted product were accomplished using Step-Tactin affinity columns and for intracellular product, a method was developed for gravity-based density separation and protein body solubilisation. The secreted protein had similar specific activity to that of the commercially available mammalian form. The intracellular version had 5-10-fold lower activity due to the enzymes incompatibility with alkaline pH. The secretion strain achieved 10% lower total biomass than either the parental or the intracellular strain. The patterns of gene induction for intracellular and parental strains were similar, whereas the secretion strain had a broader spectrum of gene expression level changes. Identification of the genes involved indicated strong secretion stress in the secretion strain and to a lesser extent also in intracellular production. Genes involved in the unfolded protein response (UPR) and ER-associated degradation were induced by GLA production, including; hac1, pdi1, prp1, cnx1, der1, and bap31.

CONCLUSIONS

Active human α-galactosidase could most effectively be produced intracellularly in Trichoderma reesei at >0.5 g/l by avoidance of the extracellular environment, although purification was challenging due to specific activity losses. Strain analysis revealed that in addition to the issues with secreted proteases, the processes of secretion stress including UPR and ER degradation remain as bottlenecks for heterologous protein production. Genetic engineering to eliminate these bottlenecks is the logical path towards establishing a strain capable of producing sensitive heterologous proteins.

Delphi consensus on the current clinical and therapeutic knowledge on Anderson-Fabry disease

BACKGROUND

Management of Anderson-Fabry disease (AFD) is contentious, particularly regarding enzyme replacement therapy (ERT). We report results of a Delphi consensus panel on AFD management.

METHODS

A survey to gauge consensus among AFD experts was distributed online and responses were analysed. Statements on: 1) diagnosis; 2) when starting ERT; 3) management of ERT infusion and adverse reactions; and 4) follow-up/monitoring response to therapy and progression of disease were included. Responses without consensus were discussed with an enlarged panel and modified to reach consensus.

RESULTS

15 experts responded to the survey. After plenary discussion among the enlarged panel, consensus was reached on most statements. Key points were the use of a target organ biopsy to show Gb3 deposits in symptomatic women with negative molecular analysis, the need for ERT in symptomatic women and in all patients with persistent signs and symptoms ± organ damage. It was agreed to assess vital signs before ERT administration and use a 0.2 μL filter on infusion to reduce the risk of adverse reactions, that serum should be drawn prior to the first infusion for anti-agalsidase antibody analysis to have a baseline value if a subsequent adverse reaction appears, and that pre-medication is required in those with prior infusion reactions. Holter ECG monitoring, cardiac and brain MRI, renal parameters, and abdominal ultrasound were considered important for the assessment of disease progression and response at ERT.

CONCLUSIONS

This consensus supplies guidance to healthcare providers on best practice in the management of patients with AFD and indicates a need for more guidance.