First treatment for Hunter disease

An article reporting results from a pivotal clinical trial that helped gain U.S. Food and Drug Administration approval for the first treatment for Hunter disease has been published online by the journal Genetics in Medicine.

Lead author is Dr. Joseph Muenzer, an associate professor in the Department of Pediatrics at the UNC School of Medicine. Muenzer led the Phase II/III clinical trial, which found that weekly infusions of idursulfase (recombinant human iduronate-2-sulfatase) are effective in treating the underlying enzyme deficiency in patients with Hunter syndrome.

Based on these results, the FDA on July 24 approved Elaprase, an idursulfase preparation manufactured by Shire Human Genetic Therapies Inc. of Cambridge, Mass.

"For the families of patients with Hunter syndrome, FDA approval of Elaprase gives them hope," Muenzer said. "Prior to this, they had no hope. These were children who were destined to die in their teenage years and early 20s. Now, they have a treatment that arrests or halts the disease process," Muenzer said.

Muenzer is recognized as one of the world's leading experts in Hunter syndrome research and the medical treatment of children with genetic lysosomal storage diseases such as Hunter syndrome.

In his laboratory at UNC, Muenzer created a mouse model for Hunter syndrome that was used in earlier research that demonstrated the potential effectiveness of Elaprase.

Hunter syndrome, known more formally as mucopolysaccharidosis type II or MPS II, is an extremely rare inherited enzyme disorder that occurs almost exclusively in males.

People with Hunter syndrome lack the enzyme iduronate-2-sulfatase, which is essential for recycling complex carbohydrates such as glycosaminoglycans, or GAG. The accumulation of GAG in tissues and organs leads to severe problems that can include joint stiffness, breathing difficulties, heart problems, enlargement of the spleen and liver, coarsening of facial features and skeletal deformities, developmental delays and neurologic disease, and, ultimately, an early death. Muenzer estimates there are only about 500 people with Hunter syndrome in the United States.

"We're pleased that ELAPRASE, the first approved treatment for Hunter syndrome, is now on the market and available to patients," said David Pendergast, president of Shire Human Genetic Therapies. "Dr. Muenzer played a key role in the clinical trials of this drug, leading to successful FDA approval."

Sixteen-year-old Cody Paxton, who was the first patient enrolled in the Phase II/III trial at UNC Hospitals, says the weekly, 3-hour infusions of Elaprase have helped him tremendously since he started receiving them in September 2004.

"My breathing is better, and I'm more energetic," he said. Plus, Cody said, he has much more flexibility in his joints. Now he can place a hand behind his head, which he could not do before, he said.