P004: Real-world clinical profiles of patients with alpha-mannosidosis: Baseline evaluations from the SPARKLE Registry

Pompe disease is a glycogen storage disease caused by acid α-glucosidase enzyme deficiency. Currently, the unique treatment is lifelong enzyme replacement therapy ERT with frequent intravenous administration of the recombinant analog alglucosidase-α (AGA), which ultimately generates a sustained humoral response resulting in treatment discontinuation. Our aim is to use the tolerogenic properties of antigen-encapsulated red blood cells (RBCs) to abolish the humoral response against AGA and to restore tolerance to replacement therapy. To demonstrate that our approach could prevent the AGA-induced immune response, mice were intravenously injected three times with AGA encapsulated into RBCs before being sensitized to AGA with several adjuvant molecules. Control animals received injections of free AGA instead of the encapsulated molecule. One-week after treatment with AGA-loaded RBCs, a strong decrease in specific humoral response was observed despite three stimulations with AGA and adjuvant molecules. Furthermore, this specific immunomodulation was maintained for at least two months without affecting the overall immune response. AGA-loaded RBCs represent a promising strategy to induce or restore tolerance in Pompe disease patients who develop hypersensitivity reactions following repeated AGA administrations.