Nexviazyme (avalglucosidase alfa-ngpt) is an enzyme replacement therapy used to treat late-onset Pompe disease (GAA deficiency) in children aged 1 year and older. This genetic disorder causes a deficiency in the enzyme needed to break down glycogen, leading to muscle weakness, heart issues, and breathing problems. Nexviazyme works by replacing the missing enzyme, avalglucosidase alfa, to break down excess glycogen and alleviate symptoms associated with the disease.