MO035HISTORICAL CONTROL ANALYSIS DEMONSTRATES SUPERIOR REDUCTION OF PLASMA GLOBOTRIAOSYLCERAMIDE BY VENGLUSTAT COMPARED WITH PLACEBO OR AGALSIDASE BETA IN CLASSIC FABRY DISEASE PATIENTS

Abstract Background and Aims Fabry disease (FD) is a rare, X-linked, genetic disorder caused by pathogenic variants in the gene for the lysosomal enzyme alpha-galactosidase A (αGal-A). The progressive accumulation of glycosphingolipids, most notably globotriaosylceramide (GL-3), leads to renal, cardiovascular, and other clinical manifestations over decades. In a single-arm phase 2 study, glucosylceramide synthase inhibition with venglustat led to a reduction in lysosomal GL-3 inclusions in skin capillary endothelial cells, as well as a progressive reduction in plasma GL-3 to normal levels by 26 weeks, with a continued decrease to low-normal levels after 3 years of therapy. We used patient data from a previously completed placebo-controlled phase 3 study of agalsidase beta (Fabrazyme) as historical control to compare the effect of venglustat treatment with placebo over 6 months and with agalsidase beta over 3 years. Methods In the venglustat phase 2 study, previously untreated classic FD patients were treated with daily venglustat for up to 3 years (NCT02228460, NCT02489344). For comparison to placebo, change in plasma GL-3 levels after 26 weeks of venglustat treatment was compared with matched historical control data from previously untreated classic FD patients who were treated for 20 weeks with placebo in the phase 3 agalsidase beta study (Eng et al, N Engl J Med 345:9, 2001). For comparison to agalsidase beta, the historical control arm was matched patients treated with agalsidase beta in the phase 3 study; change in plasma GL-3 was compared at multiple time points up to 3 years. Entry criteria and baseline characteristics were similar between the two studies. Due to the much larger numbers of patients in the phase 3 agalsidase beta study, venglustat patients were matched 1:X (variable match) with control (placebo or agalsidase beta) patients based on propensity scores using baseline variables of age, plasma GL-3, gender, UPCR (< 500 vs 500-1000 vs >1000 mg/g), and eGFR (<80 vs >= 80 mL/min/1.73m2) as matching variables. Plasma GL-3 was measured at Sanofi Genzyme by LC/MS/MS, using the same method for the two studies, with controls in place to assure assay consistency. Results Venglustat patients (N=11) were matched to 19 patients for the placebo comparison and to 28 patients for comparison to Fabrazyme. All patients in all 3 groups were male and had elevated plasma GL-3, UPCR <500 mg/g, and eGFR ≥80 mL/min/1.73m2 at baseline. Mean ages in the 3 groups were 26.6, 25.7, and 26.5 years after matching, respectively. Venglustat treatment for ∼6 months led to a highly significant reduction in plasma GL-3 compared to placebo of 3.62 vs 1.06 µg/mL (p <0.0001). Long-term treatment with venglustat yielded similar reductions in plasma GL-3 compared to agalsidase beta for the first year of treatment, but while GL-3 levels reached a plateau with agalsidase beta, the reduction with venglustat continued with longer treatment and was significantly greater than that of agalsidase beta after 2 years (p=0.0351) or 3 years (p=0.0081) (Figure). Plasma GL-3 levels after 3 years of treatment were 1.90 and 4.44 µg/mL for venglustat and agalsidase beta, respectively (normal range ≤7.02 µg/mL). Conclusions Glucosylceramide synthase inhibition with venglustat led to a significantly greater reduction in plasma GL-3 compared to placebo after 6 months, and treatment for 2-3 years led to a significantly greater reduction in plasma GL-3 compared with agalsidase beta. These results highlight the potential of long-term treatment venglustat to reverse the accumulation of GL-3 in classic FD.