Nulibry (fosdenopterin) was the first therapy approved for molybdenum cofactor deficiency Type A, an ultra-rare metabolic disorder that is usually fatal in infancy and had nothing to change its course.
It supplies cPMP, the substrate these patients cannot synthesize, allowing the body to make molybdenum cofactor and clear the neurotoxic sulfite that otherwise accumulates. The daily intravenous infusion is approved to reduce the risk of death in molybdenum cofactor deficiency Type A.
Nulibry remains the only approved therapy for the condition and holds orphan drug designation with no competing entrants. Its ultra-rare population and daily infusion burden make it a reference case for how ultra-orphan metabolic assets are valued and positioned.
