Stability of alglucosidase alfa in 0.9% sodium chloride for enzyme replacement therapy in patients with Pompe disease: insights from enzyme activity and cellular uptake measurements

Objectives Enzyme replacement therapy (ERT) with alglucosidase alfa is the cornerstone of treatment for Pompe disease, a rare disorder caused by acid α-glucosidase (GAA) deficiency. Since 2008, home infusions have been provided in the Netherlands. However, the short shelf-life of the ready-to-administer infusions poses challenges for manufacturing and dispensing pharmacies. This study assessed the stability of ready-to-administer alglucosidase alfa infusions by determining enzyme activity and cellular uptake of two concentrations during 11 days of storage. Methods Alglucosidase alfa infusions (2 and 4 mg/mL in 0.9% sodium chloride) were prepared and samples were drawn on days 1 to 7 and 11. Enzyme activity was determined using 4-methylumbelliferyl-α-D-glucoside (4MU-αGlc) and glycogen as substrates. Additionally, enzyme uptake in cultured fibroblasts was investigated. Results There was no difference in enzyme activity after 11 days as compared with day 1 using 4MU-αGlc (2 mg/mL: 352 vs 331 nmol/h/mL; 4 mg/mL: 657 vs 662 nmol/h/mL) or glycogen (2 mg/mL: 183 vs 176 nmol/h/mL; 4 mg/mL: 352 vs 357 nmol/h/mL). Uptake of alglucosidase alfa in fibroblasts remained stable over 11 days, with activity ranging from 90 to 104 nmol/h/mL at 2 mg/mL and from 233 to 238 nmol/h/mL at 4 mg/mL. Linear regression analysis confirmed no statistically significant association between time and enzyme activity or uptake. Conclusions Ready-to-administer alglucosidase alfa infusion in 0.9% sodium chloride at 2–4 mg/mL is stable for 11 days when stored at 2–8°C or −20°C and protected from light. Extending the stability could enhance efficiency and flexibility for infusion preparation and home delivery, while minimising pharmaceutical waste.