#636 A phase 4, open label, multicenter prospective study of the safety and efficacy of agalsidase beta in Chinese patients with Fabry disease

Abstract

Abstract Background and Aims Fabry disease (FD) is a rare inherited lysosomal storage disease caused by pathogenic GLA gene variants which result in a deficiency of the enzymatic activity of α-galactosidase A. Enzyme replacement therapy (ERT) is the mainstay of FD-specific treatment, but there are currently no reported clinical trials of ERT for FD in the Chinese population. This is the first phase 4 study to evaluate the safety and efficacy of ERT for FD in China since the approval of agalsidase beta in China in 2019. Method A 54-week, phase 4, open label, single arm, prospective, post-marketing surveillance (PMS) study of agalsidase beta (NCT05054387) was performed at 6 sites in China. Twenty-two Chinese ERT-naïve FD participants (≥8 years) with estimated glomerular filtration rate (eGFR) ≥30 mL/min/1.73 m2 were enrolled and received infusions of agalsidase beta (Fabrazyme®, Sanofi) at a dose of 1.0 mg/kg every 2 weeks for up to 48 weeks. The primary endpoint was safety and tolerability of agalsidase beta. The endpoints of clinical efficacy included the changes of plasma globotriaosylceramide (GL-3), globotriaosylsphingosine (Lyso-GL-3), FD symptoms (including angiokeratoma, hypohidrosis, anhidrosis, abdominal pain, headache, tinnitus, heat tolerance, and activity tolerance), and eGFR from baseline to week 48. A post-hoc subgroup analysis was conducted to explore the differences in ERT efficacy between two subgroups of different ages (<30 years and ≥30 years). Results All 22 patients completed the study intervention. There were 18 males (81.8%) and the mean age of ERT initiation was 29.0 ± 13.5 years. Treatment-related adverse events (AEs) and infusion-associated reactions (IARs) were reported in 8 participants (36.4%), which was less than ∼60% as previously reported for IARs. Most AEs were mild or moderate and no AE caused permanent treatment discontinuation or death. The mean plasma GL-3 and Lyso-GL-3 levels decreased remarkably at week 6 and remained stable throughout the trial, with the mean percentage reduction from baseline to week 6 through week 48 ranged from −34.6% ± 27.4% to ­41.9% ± 14.9% and −58.8% ± 20.2% to ­64.9% ± 12.7%, respectively (Fig. 1a and b). The reduction was more remarkable for the classic male patients (n = 18; GL-3: 7.99 ± 2.19 ug/mL at baseline and 4.31 ± 1.71 ug/mL at week 48, −46.0% ± 18.4%; Lyso-GL-3: 83.11 ± 25.69 ng/mL at baseline and 25.89 ± 13.43 ng/mL at week 48, −67.8% ± 17.6%). Thirteen (59.1%) participants experienced improved FD symptoms at week 48, with no cases of worsening symptoms. The mean eGFR was 115.6 ± 37.3 mL/min/1.73 m2 at baseline and 118.4 ± 42.9 mL/min/1.73 m2 at week 48, with a change of 0.0 ± 12.4 mL/min/1.73 m2 from baseline to week 48 (Fig. 1c). In the subgroup analysis, participants were divided into the younger group with age <30 years (n = 11) and the older group with age ≥30 years (n = 11) according to their age of ERT initiation. At week 48, the reduction of mean plasma GL-3 (−47.1% ± 23.6% vs −22.0% ± 26.0%) and Lyso-GL-3 levels (−72.4 ± 17.3% vs −48.2% ± 19.8%), the stabilization of renal function (the mean change of eGFR from baseline to week 48: 5.2 ± 7.9 mL/min/1.73 m2 vs −5.2 ± 14.1 mL/min/1.73 m2) and the percentage of symptom improvement (81.8% vs. 36.4%) were generally more remarkable in the younger group than in the older group (Table 1). Conclusion This first phase 4 study of ERT for Fabry disease in China demonstrates that agalsidase beta is safe and well tolerated with a relatively low IAR rate, and effective in reducing plasma GL-3 and Lyso-GL-3, improving symptoms, and stabilizing renal function in Chinese patients with FD. Furthermore, the present study implies that patients who initiate ERT at a younger age benefit more from the therapy. Funding: Commercial support - Sanofi Pharmaceuticals.