- Sanofi has won Food and Drug Administration approval to sell Xenpozyme, the first treatment specifically for an extremely rare genetic disease known as acid sphingomyelinase deficiency, or ASMD.
- The condition affects less than 120 people in the U.S., almost two-thirds of whom are children, Sanofi said Wednesday. Infants with the most severe form usually die before they reach the age of three.
- As a reward for developing a treatment for a rare pediatric disease, the FDA also gave Sanofi a priority review voucher that it can use itself or sell to another drugmaker. The coveted regulatory fast passes can still command substantial prices: Marinus Pharmaceuticals recently sold one to Novo Nordisk for $110 million.
The approval comes after more than two decades of research and development by rare disease specialist Genzyme, which Sanofi bought in 2011 for $20.1 billion.
Patients with ASMD suffer from a lack of an enzyme needed to break down a lipid known as sphingomyelin that can build up in cells and affect organ function, leading to debilitating symptoms. Xenpozyme, given by infusion every two weeks, is designed to replace the missing enzyme.
“There is a critical need to increase treatment options for patients who suffer from this rare disease,” Christine Nguyen, deputy director of the FDA’s pediatric rare disease office, said in the agency’s press release Wednesday. ASMD has historically been known as Niemann-Pick Types A, A/B and B.
With such a small patient base, the treatment will be expensive. The wholesale acquisition cost of one vial of the medicine is $7,142, Sanofi said. For an adult weighing about 142 pounds, the annual wholesale cost would run to nearly $1.56 million. It would be around $643,000 for a child weighing 51 pounds, which was the average patient weight in Sanofi’s pediatric trial.
Actual costs to patients will vary depending on insurance and programs, such as those that offer co-pay support. Sanofi also said in an email to BioPharma Dive that it’s “committed to helping eligible U.S. patients access the support they need and to help reduce barriers throughout their treatment journey.”
The FDA approved the medication based on study of 31 adult patients who either received Xenpozyme or a placebo. Researchers found significant improvements in lung function and reduced liver and spleen size among patients who got Xenpozyme.
Sanofi also tested the drug in a single-arm trial of eight children under 12 years old. Some 75% of pediatric patients and 50% of adult participants suffered side effects in testing, ranging from headaches to vomiting.