Ultragenyx Pharmaceutical approved Mepsevii (vestronidase alfa-vjbk) to treat mucosaccharide storage syndrome (MPS VII), also known as Sly syndrome, in children and adults. Until today, patients with this rare genetic disorder had few reliable treatments.

MPS VII is an extremely rare genetic disorder that affects fewer than 150 patients worldwide and varies from patient to patient. But the vast majority of patients will have severe skeletal abnormalities, which increase with age. Patients may also have abnormal heart valves, enlarged liver and spleen, and respiratory tract stenosis. Depending on the severity of the illness, some patients die in infancy, while many children age from infancy to adolescence, dying of dry oil. For these patients, an effective treatment is urgently needed to save lives.

The disease is a form of lysosomal storage, in which the body lacks enough beta-glucuronidase. As a result, patients are unable to metabolize specific substrates, causing toxic metabolites to accumulate in the cells, causing symptoms. Mepsevii, approved today, is an enzyme replacement therapy that performs normal enzyme activity to help patients metabolize and treat the disease appropriately. This innovative treatment has previously received FDA orphan drug and fast-track accreditation.