Myozyme® (alglucosidase alfa) is indicated for use in patients with Pompe disease (GAA deficiency).

Per the Food and Drug Administration (FDA), alglucosidase alfa has been shown to improve ventilator-free survival in patients with infantile-onset Pompe disease as compared to untreated historical control, whereas use of alglucosidase alfa in patients with other forms of Pompe disease has not been adequately studied to assure safety and efficacy.

The recommended dosage regimen of alglucosidase alfa is 20 mg/kg body weight administered every 2 weeks as an intravenous infusion.

The use of alglucosidase alfa for any indication other than infantile-onset Pompe disease is considered experimental/investigational, and therefore, not covered. A participating, preferred, or network provider can bill the member for the non-covered service.

NOTE:

Coverage for alglucosidase alfa is determined according to individual or group customer benefits. Alglucosidase alfa is not reimbursable under the prescription drug benefit.

Description

Pompe disease (glycogen storage disease type II, GSDII, glycogenosis type II, acid maltase deficiency) is an inherited disorder of glycogen metabolism caused by the absence or marked deficiency of the lysosomal enzyme GAA.

In the infantile-onset form, Pompe disease results in intralysosomal accumulation of glycogen in various tissues, particularly cardiac and skeletal muscles, and hepatic tissues, leading to the development of cardiomyopathy, progressive muscle weakness, and impairment of respiratory function.

In the juvenile and adult-onset forms, intralysosomal accumulation of glycogen is limited primarily to skeletal muscle, resulting in progressive muscle weakness. Death in all forms is usually related to respiratory failure.

Alglucosidase alfa consists of the human enzyme acid alpha-glucosidase (GAA) encoded by the most predominant of nine observed haplotypes of this gene. Alglucosidase alfa is produced by recombinant DNA technology in a Chinese hamster ovary cell line. Alglucosidase alfa degrades glycogen.

Alglucosidase alfa provides an exogenous source of GAA. Binding to mannose-6-phosphate receptors on the cell surface has been shown to occur via carbohydrate groups on the GAA molecule, after which it is internalized and transported into lysosomes, where it undergoes proteolytic cleavage that results in increased enzymatic activity. It then exerts enzymatic activity in cleaving glycogen.

NOTE:

This policy is designed to address medical guidelines that are appropriate for the majority of individuals with a particular disease, illness, or condition. Each person's unique clinical circumstances may warrant individual consideration, based on review of applicable medical records.

Under the Federal Employee Program, all services that utilize FDA-approved drugs, devices, or biological products are eligible when intended for the treatment of a serious or life-threatening condition and when medically necessary and appropriate for the patient’s condition.

Myozyme® (alglucosidase alfa)[package insert]. Genzyme Corporation, Cambridge, MA, 01/2009.

Myozyme® (alglucosidase alfa) package insert with updated prescribing information. (6829 10/2007)Genzyme Corporation, Cambridge, MA

Clinical manifestation and natural course of late-onset Pompe's disease in 54 Dutch patients, Brain (2005), 128

Course of Disability and Respiratory Function in Untreated Late-Onset Pompe Disease, Neurology, Vol.66, No. 4, 02/2006

Genzyme Study of Myozyme for Late-Onset Pompe Patients Meets Co-Primary Efficacy Endpoints, Genzyme Press Release, Cambridge, MASS, December 13, 2007