Treatment switch in Fabry disease- a matter of dose?

BACKGROUND: Patients with Fabry disease (FD) on reduced dose of agalsidase-beta or after switch to agalsidase-alfa show a decline in chronic kidney disease epidemiology collaboration-based estimated glomerular filtration rate (eGFR) and a worsened plasma lyso-Gb3 decrease. Hence, the most effective dose is still a matter of debate. METHODS: In this prospective observational study, we assessed end-organ damage and clinical symptoms in 78 patients who had received agalsidase-beta (1.0 mg/kg) for >1 year, which were assigned to continue this treatment (agalsidase-beta, regular-dose group, n=17); received a reduced dose of agalsidase-beta and subsequent switch to agalsidase-alfa (0.2 mg/kg) or a direct switch to 0.2 mg/kg agalsidase-alfa (switch group, n=22); or were re-switched to agalsidase-beta after receiving agalsidase-alfa for 12 months (re-switch group, n=39) with a follow-up of 88±25 months. RESULTS: No differences for clinical events were observed for all groups. Patients within the re-switch group started with the worst eGFR values at baseline (p=0.0217). Overall, eGFR values remained stable in the regular-dose group (p=0.1052) and decreased significantly in the re-switch and switch groups (p<0.0001 and p=0.0052, respectively). However, in all groups males presented with an annual loss of eGFR by -2.9, -2.5 and -3.9 mL/min/1.73 m² (regular-dose, re-switch, switch groups, all p<0.05). In females, eGFR decreased significantly only in the re-switch group by -2.9 mL/min/1.73 m² per year (p<0.01). Lyso-Gb3 decreased in the re-switch group after a change back to agalsidase-beta (p<0.05). CONCLUSIONS: Our data suggest that a re-switch to high dosage of agalsidase results in a better biochemical response, but not in a significant renal amelioration especially in classical males.