Influence of Treatment Effect Modifiers in Fabry Disease: A Systematic Literature Review.

Objectives: Fabry disease (FD) is a rare metabolic disorder which presents with considerable heterogeneity in disease characteristics. Given the absence of interventional studies comparing all available treatments, it is important for indirect treatment comparisons (ITCs) to account for potential treatment effect modifiers (TEMs). This systematic literature review (SLR) aimed to identify patient characteristics that may impact clinical outcomes by analyzing real-world evidence (RWE) in FD.

Methods: An SLR was conducted according to PRISMA guidelines, with searches performed in the EMBASE, MEDLINE, and Cochrane databases (1946-2022; with a recent update in April 2023). Full-text articles reporting clinical outcomes from RWE studies of pharmacological therapies for the treatment of FD were included.

Results: Including studies from the recent SLR update, a total of 119 original studies met the PICOS criteria and 25 studies provided insights into TEMS. Potential TEMs in FD were identified: sex, age, timing of treatment initiation (early/delayed), left ventricular hypertrophy (LVH), estimated glomerular filtration rate (eGFR), proteinuria, presence of anti-drug-antibodies (ADAs) at baseline, and previous enzyme replacement therapy (ERT). In three studies (two including ERT-treated patients and one study of migalastat-treated patients) males showed worse renal outcomes than females. Five studies found that younger patients and those who received initial ERT before the age of 25 years had greater reductions in plasma-lysoGb3, as well as more favorable renal, cardiac, and biochemical outcomes. Seven studies identified associations between LVH and reduced eGFR at baseline, along with an increased risk of cardiovascular, renal, and neurological events. In four studies, lower baseline eGFR and proteinuria were associated with faster annual eGFR decline despite ERT; high baseline proteinuria was a significant predictor of renal disease progression. Baseline ADAs were linked to lower eGFR, increased left ventricular mass, and reduced treatment impact on plasma/urine-lysoGb3. Migalastat was effective in treatment-naïve patients, while those previously treated with ERT experienced deteriorations in mean lysoGb3, eGFR, and left ventricular mass.

Conclusions: This SLR highlighted several patient characteristics that influence treatment effectiveness in FD. It is important to account for these characteristics in ITCs to ensure unbiased outcomes.