FDA Approves First Treatment for Rare Genetic Metabolic Pediatric Disorder

The FDA approved the first therapy for an ultra-rare genetic metabolic disorder that affects infants, who don’t normally live past the age of 4.

The disorder is known as molybdenum cofactor deficiency (MoCD) Type A, which presents shortly after birth, often with severe encephalopathy and intractable seizures.

The approval for the injection, fosdenopterin (Nulibry), was granted to BridgeBio Pharma and its affiliate, Origin Biosciences.

A progressive disease, MoCD Type A affects fewer than 150 patients across the globe. It is characterized by an inability to produce cyclic pyranopterin monophosphate (cPMP). The injection replaces missing cPMP in treated patients.

"Today's action marks the first FDA approval for a therapy to treat this devastating disease," Hylton V. Joffe, MD, MMSc, director of the Office of Rare Diseases, Pediatrics, Urologic and Reproductive Medicine in the FDA's Center for Drug Evaluation and Research, said in a statement. "The FDA remains committed to facilitating the development and approval of safe and effective therapies for patients affected by rare diseases—an area of critical need."

BridgeBio’s Origin submitted a new drug application with the FDA for in December 2019. The FDA reviewed the injection under Priority Review, and the therapy received Orphan Drug Designation, Breakthrough Therapy Designation and Rare Pediatric Disease Designation. In addition, the agency issued a Rare Pediatric Disease Priority Review Voucher (PRV) to Origin.

The FDA said efficacy was established in 13 patients administered fosdenopterin, compared with 19 matched, untreated patients. The therapy was linked with a survival rate of 84% at 3 years, compared with 55% among untreated patients.

The most common side effects included complications related to the intravenous line, fever, respiratory infections, vomiting, gastroenteritis, and diarrhea.

The companies said that treatment with fosdenopterin in 3 studies was also associated with a marked reduction in urine concentrations of S-sulfocysteine (SSC), a toxic substance that is associated with neurological damage in patients with MoCD Type A. The studies show that the reduction in SSC was sustained over 48 months with long-term use of fosdenopterin.