FDA approves $4 million gene therapy for Sanfilippo syndrome

The Food and Drug Administration granted approval in September for a new gene therapy designed to treat Sanfilippo syndrome. The one-time infusion, branded Fayuvi, carries a price tag of nearly $4 million. This cost places it as the second most expensive gene therapy available, according to 46brooklyn, a drug price research firm. The approval provides a new treatment option for children with the inherited metabolic disorder.

Sanfilippo syndrome is a rare condition caused by a faulty gene that prevents the body from breaking down heparin sulfate. As this molecule accumulates in cells, it leads to severe physical and developmental complications. Children with the disease typically lose the ability to speak and walk and suffer from seizures. According to the Cure Sanfilippo Foundation, patients usually do not survive past their teenage years.

Research into a genetic cure began in the late 1990s at Nationwide Children's Hospital in Columbus, Ohio. Haiyan Fu, a researcher there, developed a therapy using a modified virus to deliver a working copy of the gene to patients. Fu noted that early treatment could potentially serve as a cure, stating, "So I can't give up." However, funding remained a persistent challenge. In 2009, Fu considered quitting the project but was encouraged to continue by the families of affected children.

Eight patient foundations, including Ben's Dream and a Cure for Kirby, provided financial support to keep the research alive. Glenn O'Neill, a father of a child with the disease, helped raise additional funds through a viral video campaign in 2014. The effort, known as Saving Eliza, broke the GoFundMe record at the time by raising $1 million in weeks. The total amount raised soon reached $2 million, helping to finance the first human clinical trial that began in May 2016.

Eliza O'Neill became the first patient to receive the therapy during that trial. She was six years old at the time of treatment. Her mother, Cara O'Neill, is a pediatrician who recalled the shock of the diagnosis in 2013. Cara stated, "When they said the word, it all kind of came rushing back," referring to her medical school lessons on the disease. Glenn O'Neill described the urgency felt by the family after learning about the rapid progression of the condition. He said, "Whatever we need to do, we need to do it now."

The biotech company Ultragenyx acquired the rights to the therapy in 2022. The company continued its studies and submitted data to the FDA for review. Emil Kakkis, the CEO of Ultragenyx, emphasized the importance of early intervention. He explained that the treatment works best in younger children because more brain tissue remains intact. Kakkis noted that some children treated at six months of age showed positive results. He added, "We understand what [we've] got to do" regarding patient access.

Following the FDA announcement, researcher Haiyan Fu received calls from Cara O'Neill and other families who had funded her early work. Fu described the approval as good news but noted the mixed emotions involved. She remarked, "It shouldn't take this long." Eliza O'Neill is now nearly 17 years old. Although she lost her ability to speak before her treatment, she communicates using picture cards and devices. She attends school and learned to swim this summer.

Ultragenyx stated it is committed to treating every patient regardless of cost. The company aims to remove logistical or geographic barriers to care. The approval of Fayuvi concludes a long process that began with mouse studies in the late 1990s and involved significant private fundraising. The therapy is now available for use in the United States.