Sanofi’s Nexviazyme Shows Positive Phase 3 Results in Infantile Pompe Diseas

Sanofi has reported positive Phase 3 results for Nexviazyme, also known as avalglucosidase alfa, in infants with infantile-onset Pompe disease, a rare and life-threatening genetic neuromuscular disorder.

Results from the Baby-COMET Phase 3 study showed that Nexviazyme met its primary endpoint in treatment-naïve pediatric patients aged six months and younger. The study evaluated the proportion of infants who were alive and free from invasive ventilation after 52 weeks of treatment.

The single-arm, open-label clinical trial also met all secondary endpoints, including survival without invasive ventilation at 12 and 18 months of age. Researchers additionally reported numerical improvements in measures related to disease progression after 52 weeks of treatment, including cardiac and motor outcomes.

The Baby-COMET data are scheduled to be presented on July 8, 2026, at the 19th International Congress on Neuromuscular Diseases in Florence, Italy. Sanofi said the results are expected to support a U.S. regulatory submission for a potential label expansion for Nexviazyme in infantile-onset Pompe disease during the second half of 2026.

Pompe disease is a rare inherited metabolic disorder caused by a deficiency of the acid alpha-glucosidase, or GAA, enzyme. The enzyme is needed to break down glycogen, a stored form of sugar, inside cells. When GAA activity is absent or severely reduced, glycogen accumulates in tissues, particularly skeletal and cardiac muscle, leading to progressive muscle weakness, heart complications and breathing difficulties.

Infantile-onset Pompe disease, or IOPD, is the most severe form of the condition. Symptoms typically emerge in the first weeks or months of life and can progress rapidly. Without treatment, the disease can lead to severe cardiomyopathy, respiratory failure, loss of motor function and early death.

Nexviazyme is an enzyme replacement therapy designed to improve delivery and uptake of the GAA enzyme into affected cells. By helping remove excess glycogen from muscle tissue, the therapy is intended to reduce damage to skeletal and cardiac muscles and support better long-term clinical outcomes.

In the Baby-COMET trial, Nexviazyme was generally well tolerated. Sanofi said there were no serious treatment-related adverse events, deaths or treatment discontinuations reported during the study. Infusion-associated reactions occurred in 29.4% of participants and were described as manageable.

Priya S. Kishnani, MD, a pediatric genetics specialist at Duke University Medical Center, said early intervention is critical for infants with Pompe disease because of the condition’s rapid progression. She said the Baby-COMET findings suggest avalglucosidase alfa may support invasive ventilator-free survival beyond the first year of life while also providing encouraging cardiac and motor outcomes.

Christopher Corsico, Global Head of Development at Sanofi, said the results could help expand treatment access for infants and families affected by Pompe disease. He added that the data are consistent with earlier research involving Nexviazyme and reflect continued efforts to improve treatment options for the Pompe disease community.

Nexviazyme is already approved in several countries for Pompe disease, although its approved use varies by market. In the United States, the therapy was approved in 2021 for late-onset Pompe disease in patients aged one year and older. In Europe, it is marketed as Nexviadyme and was approved in 2022 for long-term enzyme replacement therapy in patients with both late-onset and infantile-onset Pompe disease.

Nexviazyme remains investigational for infantile-onset Pompe disease in the United States, and its safety and effectiveness for this specific patient population have not yet been evaluated by the U.S. Food and Drug Administration.