GAA engineered to improve cellular uptake enhances correction in a preclinical hematopoietic stem cell gene therapy model of Pompe disease.

Pompe disease (PD) is a severe autosomal-recessive lysosomal storage disorder in which deficiency of acid alpha-glucosidase (GAA) enzyme function results in glycogen accumulation and a spectrum of clinically severe neuromuscular disease. Enzyme replacement therapy is the standard of care for PD, although its efficacy is limited by inefficient uptake by cells in target organs. Autologous transplantation of hematopoietic stem cells (HSCs), genetically modified ex vivo with lentiviral vectors (LVVs), allows secretion and systemic delivery of lysosomal enzymes and has resulted in clinical correction of severe neurometabolic diseases. We evaluated the potential of HSC gene therapy to correct GAA deficiency in a murine model of PD. To improve lysosomal delivery, we engineered a novel GAA transgene by adding a peptide tag targeting the insulin-like growth factor 2 binding domain (vIGF2-GAA). Transplantation of Gaa -/- HSCs genetically modified to express vIGF2-GAA into Gaa -/- recipient mice resulted in sustained systemic levels of engineered GAA. Reduction of glycogen accumulation in muscle tissues and brain confirmed the superior activity of vIGF2-GAA compared to wild-type (WT) GAA, lowering urine glucose tetrasaccharide levels and correcting skeletal and cardiac phenotypes. These results demonstrate the therapeutic advantage of delivering engineered vIGF2-GAA and support the clinical translation of HSC gene therapy for PD.