Recent developments, utilization, and spending trends for pompe disease therapies

Pompe disease is a rare condition, with an incidence rate estimated to be between 1 in 40,000 and 1 in 300,000 live births worldwide. For an infant who contracts the disease, which is an inherited metabolic myopathy caused by deficiency of the acid alpha-glucosidase (GAA) enzyme in lysosomal cells, the survival rate to age 1 year is estimated to be 25.7%. Before 2006, no therapies were available for this disease.

The goals of this study were to review recent developments in therapies for Pompe disease, including the US Food and Drug Administration (FDA) approval of 2 biologic drugs, and to describe the associated drug utilization and spending trends in the US Medicaid program for patients with this disease.

We reviewed 2 recently approved therapies for Pompe disease and compared their indications, as well as their efficacy and safety profiles. A retrospective analysis was performed using the national Medicaid pharmacy claims database. Quarterly prescriptions and reimbursement amounts were calculated for each drug from 2006 quarter 2 through 2011 quarter 2. Average per-prescription spending was calculated by dividing the drug reimbursement by the number of prescriptions written for that drug.

Myozyme (alglucosidase alfa, recombinant human GAA) and Lumizyme (alglucosidase alfa), the first 2 enzyme replacement therapies available for Pompe disease, were approved as orphan drugs by the FDA in 2006 and in 2010, respectively. Myozyme is indicated for infantile-onset Pompe disease; Lumizyme is indicated for patients aged ≥8 years. Although both drugs have been shown to improve patient survival rates, they both also have a boxed warning, because of the possibility of life-threatening allergic reactions. Moreover, Lumizyme has a restricted distribution system to ensure it is used by the correct patient population. In 2010, Medicaid spending for Myozyme was $3.6 million. In the first 2 quarters of 2011, Medicaid spending for Lumizyme was $1.8 million. Prescriptions for Myozyme increased from 1 in 2006 quarter 2 to 127 in 2011 quarter 2, whereas prescriptions for Lumizyme increased from 6 in 2010 quarter 3 to 60 in 2011 quarter 2. During the same period, expenditures rose from $9450 to $930,459 for Myozyme and from $119,691 to $1.16 million for Lumizyme. The average price per prescription was approximately $10,000 for Myozyme and approximately $20,000 for Lumizyme over the study period.

As can be expected after the FDA's approval of Myozyme and Lumizyme, Medicaid beneficiaries have experienced rising utilization of the 2 therapies. Spending by Medicaid has increased proportionately, implying a steady per-prescription average price for both drugs where if both numerator and denominator increase at the same rate, the ratio (price) should remain the same. New promising therapies for Pompe disease are currently being studied.