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# Ultragenyx NDA for Mepsevii OK’d for Rare Metabolic Condition
- URL: https://www.fdaweb.com/ultragenyx-nda-for-mepsevii-okd-for-rare-metabolic-condition/
- Published: 2017-11-15T12:00:00.000Z
- Updated: 2026-09-14T23:01:52.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5140137

FDA has approved an Ultragenyx Pharmaceutical NDA for Mepsevii (vestronidase alfa-vjbk), the first approved treatment for pediatric and adult patients with an inherited metabolic condition called mucopolysaccharidosis type VII (MPS VII), also known as Sly syndrome. MPS VII is an extremely rare, progressive condition that affects most tissues and organs.

Approval was based on data from a clinical trial and expanded access protocols enrolling a total of 23 patients ranging from 5 months to 25 years of age. Efficacy was primarily assessed through a the six-minute walk test in 10 patients who could perform the test, according to an [agency release](https://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm585308.htm?ref=fdaweb.com). “After 24 weeks of treatment, the mean difference in distance walked relative to placebo was 18 meters,” it says. “Additional follow-up for up to 120 weeks suggested continued improvement in three patients and stabilization in the others. Two patients in the Mepsevii development program experienced marked improvement in pulmonary function. Overall, the results observed would not have been anticipated in the absence of treatment.”

The most common side effects after treatment with Mepsevii include infusion site reactions, diarrhea, rash and anaphylaxis.