The U.S. Food and Drug Administration has approved a first-of-its-kind enzyme therapy for a rare and debilitating genetic disease known as phenylketonuria, or PKU. The treatment was developed in part through a clinical trial led by an OHSU physician who specializes in metabolic diseases.
Cary Harding, M.D., a professor of molecular and medical genetics in the OHSU School of Medicine, chaired a clinical trial study steering committee and treated about 20 participants involved in the multi-site phase three clinical trial in 2016. He described the FDA’s approval of the enzyme Palynziq as “truly transformative” for adults living with PKU. Treatment involves a daily injection.
Parents may be familiar with PKU by the fact that all newborn infants are screened for the disease, along with others, with a “heel stick” blood draw within 24 to 48 hours of birth.
The disease blocks the body from breaking down the amino acid phenylalanine, or Phe, in protein-containing foods and high-intensity sweeteners. The diagnosis requires strict adherence to a protein-free diet to prevent the buildup of Phe in the body, which can cause long-term damage to the central nervous system.
Adult patients typically must adhere to a strict diet free of meat, fish, eggs, nuts and dairy, yet adhering to such a strict diet carries its own burden from a health standpoint.
“It’s not about just being able to eat a hamburger,” Harding said. “It’s the physical, neurological and psychological needs not being met by contemporary therapy that we are trying to address.”
PKU affects about 1 in 10,000 to 15,000 people in the United States, according to the FDA. If untreated, it can cause chronic intellectual, neurodevelopmental and psychiatric disabilities. Lifelong restrictions of phenylalanine through the diet prevents buildup of Phe in the body.
Harding said he’s gratified by the FDA’s approval of the new treatment. He’s continuing to work toward other novel treatments for PKU, including gene therapy techniques that he’s studied in his research lab for 30 years.
“I look forward to the day when I might reach into my clinical toolbox and have a variety of different effective therapeutic tools available to offer the patient with PKU,” he said.
FDA granted approval of Palynziq to BioMarin Pharmaceutical Inc. on May 24.
In the interest of ensuring the integrity of our research and as part of our commitment to public transparency, OHSU actively regulates, tracks and manages relationships that our researchers may hold with entities outside of OHSU. In regards to this research, Dr. Harding holds financial interests in BioMarin Pharmaceutical Inc. Review details of OHSU’s conflict of interest program to find out more about how OHSU manages these business relationships.