A randomized, phase 3B, open-label, parallel-group study of agalsidase beta in treatment-naive male pediatric patients with Fabry disease without severe symptoms (FIELD study): GL-3 clearance from kidney cells

To assess the utility of globotriaosylsphingosine (lyso-Gb3) for clinical monitoring of treatment response in patients with Fabry disease receiving migalastat.A post hoc analysis evaluated data from 97 treatment-naive and enzyme replacement therapy (ERT)–experienced patients with migalastat-amenable GLA variants from FACETS (NCT00925301) and ATTRACT (NCT01218659) and subsequent open-label extension studies. The relationship between plasma lyso-Gb3 and measures of Fabry disease progression (left ventricular mass index [LVMi], estimated glomerular filtration rate [eGFR], and pain) and the relationship between lyso-Gb3 and incidence of Fabry-associated clinical events (FACEs) were assessed in both groups. The relationship between changes in lyso-Gb3 and kidney interstitial capillary (KIC) globotriaosylceramide (Gb3) inclusions was assessed in treatment-naive patients.No significant correlations were identified between changes in lyso-Gb3 and changes in LVMi, eGFR, or pain. Neither baseline lyso-Gb3 levels nor the rate of change in lyso-Gb3 levels during treatment predicted FACE occurrences in all patients or those receiving migalastat for ≥24 months. Changes in lyso-Gb3 correlated with changes in KIC Gb3 inclusions in treatment-naive patients.Although used as a pharmacodynamic biomarker in research and clinical studies, plasma lyso-Gb3 may not be a suitable biomarker for monitoring treatment response in migalastat-treated patients.