By Sriparna Roy and Kamal Choudhury
Sept 17 (Reuters) - Ultragenyx Pharmaceutical said on Thursday it has set a U.S. list price of $3.95 million for its newly approved gene therapy Fayuvi, launching one of the world's most expensive drugs as a one-time treatment for a rare, fatal childhood disease.
The U.S. Food and Drug Administration approved Fayuvi for pediatric patients with Sanfilippo syndrome Type A, an inherited condition that progressively damages the brain and nervous system.
The disease is caused
by a deficiency of an enzyme called sulfamidase, leading to an abnormal accumulation of a complex sugar molecule known as heparan sulfate in the body and brain. This toxic buildup causes children to gradually lose cognitive, speech, and motor skills.
Ultragenyx executives said on a conference call that the lifetime cost of caring for a child with the disease, who can spend years in a bedridden state, can exceed $8 million, a burden they said grows as the disease advances.
J.P. Morgan analysts estimate Fayuvi could reach peak worldwide sales of $200 million to $250 million.
Ultragenyx shares closed 12.6% higher on Thursday.
Administered as a single intravenous infusion, the gene therapy delivers a functional copy of the SGSH gene into cells, enabling the body to produce sulfamidase and clear the damaging buildup.
In trials, children treated with the therapy maintained or improved cognitive function compared with untreated patients, according to the FDA.
Glenn O'Neill, president and co-founder of nonprofit Cure Sanfilippo Foundation, whose daughter Eliza was diagnosed in 2013, and treated with the therapy in 2016 at age 6, said the approval means "real hope and a real life-changing chance to have a different outcome than the traditional course of this disease."
Eliza's parents told Reuters ahead of the decision that she has "never had a seizure" and is not on a feeding tube or in a wheelchair, and attends school and swims, outcomes they said far exceed what is typical for the disease.
Ultragenyx expects Fayuvi to be available at specialized U.S. treatment centers within 30 to 60 days.
(Reporting by Sriparna Roy and Kamal Choudhury in Bengaluru; Editing by Maju Samuel, Shilpi Majumdar and Tasim Zahid)
