NOVATO -- Ultragenyx Pharmaceutical Inc., a biotechnology company focused on developing treatments for rare and ultrarare genetic disorders, today announced that the Food and Drug Administration has granted orphan-drug designation for its UX003 treatment.

That designation covers treatments for and diagnosis or prevention of rare diseases or disorders that affect fewer than 200,000 people in the U.S. Approved "orphan" products get exclusive domestic market access for seven years, waiver or partial payment of application fees, and tax credits for clinical testing expenses conducted after that designation is received.

"Obtaining orphan drug designation for UX003 is a significant achievement for Ultragenyx that adds value to our development pipeline and attests to the importance of this product candidate in filling an unmet medical need," said Emil Kakkis, M.D., Ph.D., chief executive officer of Ultragenyx. "We look forward to continuing to collaborate with Dr. Sly and colleagues at St. Louis University to advance this urgently needed therapy into clinical testing." 

Novato has a small cluster of orphan-drug developers, starting with BioMarin Pharmaceutical and spurring startups Raptor Pharmaceutical and Ultragenyx.

UX003 is targeted at an extremely rare genetic metabolic disorder called Mucopolysaccharidosis type 7 (MPS 7), also known as Sly syndrome. It is one of 40 different lysosomal storage disorders and the rarest. Among the wide range of symptoms are enlarged organs, stiff joints and problems with lung and heart function. Currently, there is no approved therapy.

MPS 7 is named after St. Louis University School of Medicine researcher William Sly, who discovered it in 1973. Ultragenyx licensed the institution's MPS 7 program.

The autosomal recessive lysosomal storage disorder causes a deficiency of the lysosomal enzyme Beta-glucuronidase, required for the degradation of the glycosaminoglycans dermatan sulfate and heparan sulfate. UX003 is a recombinant human Beta-glucuronidase that targets MPS 7 via enzyme-replacement therapy.

MPS 7 is caused by the deficiency of Beta-glucuronidase, an enzyme required for the breakdown of the glycosaminoglycans dermatan sulfate and heparan sulfate. These complex GAG carbohydrates are a critical component of many tissues. The inability to properly breakdown GAGs leads to a progressive accumulation in many tissues and multisystem disease.

While its clinical manifestations are similar to MPS 1 and MPS 2, MPS 7 is one of the rarest among the MPS disorders and is likely underdiagnosed as are most rare diseases. MPS 7 has a wide spectrum of clinical manifestations and can present as early as at birth or in older patients with less rapidly progressive disease.

Launched last year, Ultragenyx ( is a privately held biotechnology company that focuses on rare metabolic diseases that affect small numbers of patients, but for which the unmet medical need is high and there are no effective treatments. The company received $45 million in first-round funding last year.

UX003 is Ultragenyx's second product to receive U.S. orphan designation. The first one was the company's lead product, UX001, being evaluated as a potential treatment for GNE myopathy, also known as hereditary inclusion body myopathy.