Fabry disease: clinical spectrum and evidence-based enzyme replacement therapy

Abstract

The clinical spectrum of Fabry disease, an X-linked lysosomal storage disorder due to alpha-galactosidase A (alpha-Gal A) deficiency, has been expanded beyond the classic phenotype to include the recently recognized later-onset "cardiac" and "renal" variants. The clinical manifestations in each of these disease subtypes are presented with particular emphasis on early recognition among pediatric patients as well as identification of unrecognized patients diagnosed as hypertrophic cardiomyopathy or in renal dialysis clinics. Previously, treatment of patients with Fabry disease was limited to palliative care of the excruciating pain, cardiac and cerebrovascular manifestations, and renal failure. Recently, Fabry-specific enzyme replacement therapy (ERT) with recombinant alpha-Gal A (Fabrazyme) has proven safe and effective. The preclinical, Phase 1/2 and multicenter, double-blind, randomized, placebo-controlled Phase 3 and 4 trials provided the evidence for the safety and efficacy of Fabrazyme treatment. The preclinical and Phase 1/2 studies demonstrated that enzyme delivery to various tissues and GL-3 clearance were dose-dependent. The Phase 3 clinical trial and 3-year extension study provided long-term data documenting the safety and effectiveness of 1 mg/kg of Fabrazyme for this disease. Finally, the "top-line" data from the Phase 4 trial indicates that in patients with mildly to moderately advanced renal disease, Fabrazyme can slow the progression of renal, cardiac, and cerebrovascular events taken together or individually. The Phase 4 trial results also emphasize the importance of early treatment. In sum, these clinical trials provide the evidence-based safety and efficacy of Fabrazyme replacement therapy for Fabry disease.