Enzyme replacement therapy for Fabry disease: lessons from two alpha-galactosidase A orphan products and one FDA approval.
Two virtually identical products have been developed for enzyme replacement therapy for the treatment of Fabry disease, which is a rare and debilitating genetic disease caused by decreased activity of the lysosomal enzyme alpha-galactosidase A. Lack of this enzyme results in progressive tissue accumulation of globotriaosylceramide (GL-3), resulting in life-threatening renal, cardiac and cerebrovascular complications. Both enzyme replacement products, agalsidase alfa (Replagal; Transkaryotic Therapies, Cambridge, MA, USA) and agalsidase beta (Fabrazyme; Genzyme Corporation, Cambridge, MA, USA), were approved by the European Agency for the Evaluation of Medicinal Products in 2001; agalsidase alfa at a recommended dose of 0.2 mg/kg and agalsidase beta at a recommended dose of 1 mg/kg. In the US, however, orphan drug laws dictated that only one of these products could be approved. In April 2003, after a rigorous evaluation of both products by the US FDA, this approval was granted to agalsidase beta. This decision reflected clinical trial design, how dosages were determined, antibody effects and the ability of each product to demonstrate either clinical efficacy or reduction of tissue storage of GL-3 in major organs of pathology when administered at the recommended dosage. The process also highlighted important issues in the evaluation of drugs to treat life-threatening genetic diseases for which the pathological basis is well-defined.
Department of Human Genetics, Box 1498, Mount Sinai School of Medicine, Fifth Avenue at 100th St, New York, NY 10029, USA. rjdesnick@mssm.edu
Robert J
RJ
Desnick
D000328:Adult; D000818:Animals; D001706:Biopsy; D016466:CHO Cells; D002460:Cell Line; D002626:Chemistry, Pharmaceutical; D002986:Clinical Trials as Topic / Q000379:methods / Q000592:standards; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D017277:Drug Approval / Q000331:legislation & jurisprudence*; D005060:Europe; D000795:Fabry Disease / Q000188:drug therapy*; D005260:Female; D005838:Genotype; D006801:Humans; D007518:Isoantibodies / Q000096:biosynthesis; D007527:Isoenzymes / Q000008:administration & dosage / Q000276:immunology / Q000627:therapeutic use*; D007668:Kidney / Q000378:metabolism / Q000473:pathology; D008297:Male; D009965:Orphan Drug Production / Q000331:legislation & jurisprudence*; D011994:Recombinant Proteins; D012107:Research Design; D016896:Treatment Outcome; D014281:Trihexosylceramides / Q000378:metabolism; D014481:United States; D014486:United States Food and Drug Administration; D000519:alpha-Galactosidase / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology / Q000627:therapeutic use*
D007518:Isoantibodies; D007527:Isoenzymes; D011994:Recombinant Proteins; D014281:Trihexosylceramides; C000627036:agalsidase alfa; C018549:globotriaosylceramide; D000519:alpha-Galactosidase; C459420:agalsidase beta