A Case of Avalglucosidase Treatment in a Patient with Infantile-Onset Pompe Disease (IOPD) in Korea

Background: Pompe disease (PD) is a rare lysosomal storage disease caused by glycogen accumulation in lysosomes due to a genetic deficiency of acid α-glucosidase (GAA) which degrades lysosomal glycogen. We assessed the efficacy of avalglucosidase alfa, recombinant human GAA enzyme replacement therapy (ERT) designed for enhanced mannose-6-phosphate-receptor targeting and enzyme uptake to increase glycogen clearance compared to alglucosidase alfa in patients with PD.

Methods: The patient was a 15-year-old female who was diagnosed with enzymatically confirmed Infantile-onset Pompe disease (IOPD) at 9 months of age. She was treated with alglucosidase alfa (dose: 20 mg/kg) every 2 weeks from the age of 1 to 13 and then, avalglucosidase alfa (dose: 40 mg/kg) every 2 weeks with a change in medication. Treatment efficacy was evaluated by the pulmonary function test (PFT), 6-minute walk test (6MWT), echocardiography, and K-MBI (Modified Barthel Index, activity of daily living).

Result: Avaglucosidase alfa treatment improved the PFT from a moderate restrictive pattern to a mild restrictive pattern after 1.6 years compared to alglucosidase alfa. At the same time, improvement was also seen in the 6MWT with an increase from 291 m to 354 m and in the K-MBI from 82 points to 96 points. However, echocardiography revealed no significant differences after 1.2 years compared to alglucosidase alfa.

Conclusion: Compared to alglucosidase alfa, avalglucosidase alfa improved pulmonary function, walking ability, and activities of daily living but did not affect cardiac function in our IOPD patient. Future long-term studies should be conducted on a larger number of patients.