The Food and Drug Administration (FDA) has approved Nulibry (fosdenopterin) for injection to reduce the risk of mortality in patients with molybdenum cofactor deficiency (MoCD) Type A.

MoCD Type A is a rare, inborn error of metabolism caused by mutations in the MOCS1 gene that results in toxic sulfite accumulation in the brain. The disorder typically appears shortly after birth and leads to intractable seizures, brain injury and death. Nulibry replaces missing cyclic pyranopterin monophosphate, which is needed to reduce levels of neurotoxic sulfites.

The approval was based on data from 3 clinical studies ( Study 1 [NCT02047461], Study 2 [NCT02629393], and Study 3) that was compared to data from a natural history study. Findings from a combined analysis of patients with MoCD Type A (n=13) showed that treatment with Nulibry or recombinant cPMP (rcPMP) reduced the risk of death by 82% when compared to the untreated, genotype-matched patients in the natural history control group (n=18) (hazard ratio [HR] 0.18; 95% CI, 0.04-0.72). Moreover, the survival rate at 3 years was reported to be 84% (95% CI, 49-96) in the Nulibry or rcPMP arm vs 55% (95% CI, 30-74) for untreated patients in the historical control group.

With regard to safety, the most common adverse reactions reported (incidence of greater than or equal to 25%) with Nulibry were catheter-related complications, pyrexia, viral infection, pneumonia, otitis media, vomiting, cough/sneezing, viral upper respiratory infection, gastroenteritis, bacteremia, and diarrhea. Additionally, the treatment has been identified through animal studies as having phototoxic potential.

Nulibry is supplied as a single-dose vial containing 9.5mg of fosdenopterin (equivalent to 12.5mg fosdenopterin hydrobromide as a dihydrate) as a lyophilized powder or cake for reconstitution for intravenous infusion.

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1.    FDA approves first treatment for molybdenum cofactor deficiency Type A. [press release]. Silver Springs, MD: US Food and Drug Administration (FDA); February 26, 2021. 

2.    BridgeBio Pharma and Affiliate Origin Biosciences announce FDA approval of Nulibry™ (fosdenopterin), the first and only approved therapy to reduce the risk of mortality in patients with MoCD Type A. [press release]. Palo Alto, CA: BridgeBio Pharma, Inc. and Origin Biosciences, Inc.; February 28, 2021.

3.    Nulibry [package insert]. Boston, MA: Origin Biosciences, Inc.; 2021.