Article: FDA Approves First Treatment for Genetic Metabolic Disorder Including Hurler Disorder

The Food and Drug Administration (FDA) today approved the first treatment for patients with certain forms of a rare genetic disease called MPS I, which includes Hurler Syndrome. This disease results from the absence or malfunctioning of an enzyme that breaks down molecules called glycosaminoglycans (GAG) in the cells. The build up of GAG in the cells of patients with MPS I results in progressive cellular damage that affects appearance, physical abilities, organ functions and, in some cases, mental development.

The new biotechnology product, Aldurazyme (laronidase), is a version of the human form of the deficient enzyme. This new biotechnology product helps prevent the build-up of GAG in the cells and has been shown to improve lung function and exercise ability. It was designated as a priority new drug under FDA’s prescription drug user fee program; the initial review was completed within six months of application receipt, and it was approved within 9 months of application receipt. Aldurazyme’s approval is for patients with Hurler and Hurler-Scheie forms of MPS I as well as patients with the Scheie form with moderate to severe symptoms.

Hurler syndrome is the most severe of the MPS I forms. Affected children often die early from respiratory diseases and cardiac complications. Hurler-Scheie syndrome is less severe, but patients usually do not survive beyond their early 20’s. Scheie syndrome is the mildest form with many patients living well into adulthood, but these patients can still have deformities, heart disease and difficulty breathing. According to the National Institutes of Health, studies in Canada estimate one in 100,000 babies born has Hurler syndrome. The estimate for Hurler-Scheie syndrome is one in 115,000 and for Scheie syndrome, it is one in 500,000.

Aldurazyme was studied in a randomized, placebo-controlled study of 45 MPS I patients, most of whom had Hurler-Scheie. After 26 weeks, patients receiving the product had improved lung function and walking capacity based on a six-minute walk test. There is no evidence that the new product has any positive effects on central nervous system (CNS) symptoms such as developmental delay and hydrocephalus.

The most serious adverse reaction reported with Aldurazyme was an anaphylactic (allergic) reaction occurring approximately three hours after the product was infused that required an emergency tracheostomy (an opening in the neck to help breathing) in a patient with severe lung problems.

The most common adverse reactions were upper respiratory tract infection, rash, and injection site reactions. The main safety concerns related to infusion reactions included flushing, fever, headache and rash.

In addition to its designation as a priority new drug, Aldurazyme is an orphan drug. The orphan drugs program provides incentives for companies to develop new treatments for rare diseases that affect fewer than 200,000 people in the U.S. The Orphan Drug Act provides a seven-year period of exclusive marketing to the first sponsor who obtains marketing approval for a designated orphan drug.

Aldurazyme is manufactured by BioMarin Pharmaceuticals of Novato, Calif.