Sanofi announced that its therapy Nexviazyme met all primary and secondary endpoints in the Baby-COMET phase 3 study for infantile-onset Pompe disease (IOPD). The study demonstrated that treatment-naïve pediatric participants aged six months and younger remained alive and free of invasive ventilation at 52 weeks of treatment. The company intends to submit this data to support a regulatory application in the US in the second half of 2026.

The Baby-COMET phase 3 study is a single-arm, open-label, international, multicenter trial evaluating Nexviazyme in treatment-naïve pediatric participants with IOPD aged 12 months and younger. Seventeen participants received intravenous Nexviazyme 40 mg/kg every other week. The primary endpoint was the proportion of participants alive and free of invasive ventilation at week 52.

Key Study Findings

Nexviazyme was well tolerated in the study, with a safety profile consistent with the established profile of avalglucosidase alfa. There were no serious treatment-related treatment-emergent adverse events, deaths, or discontinuations reported. Manageable infusion-associated reactions occurred in 29.4% of participants.

Regulatory and Clinical Background

The results will be presented on July 8, 2026, at the 19th International Congress on Neuromuscular Diseases in Florence, Italy. Currently, Nexviazyme is approved in the US for the treatment of late-onset Pompe disease (LOPD) in patients one year of age and older, a status it received in 2021. In Europe, the medicine is available under the name Nexviadyme and received approval for the long-term enzyme replacement therapy of patients with Pompe disease (LOPD and IOPD) in 2022.

Pompe disease is a rare, inherited, progressive neuromuscular disorder caused by a deficiency of the acid alpha-glucosidase (GAA) enzyme. IOPD is the most aggressive variant, manifesting with swift symptom progression during the first months of life. Without therapeutic intervention, IOPD can lead to severe and potentially fatal complications affecting the heart, breathing, and movement. Nexviazyme is designed to help enter cells and improve uptake of the essential GAA enzyme, potentially clearing excess glycogen buildup in muscle cells.

The European Commission has launched a formal antitrust investigation into Sanofi to determine whether the French drugmaker violated EU competition rules through a communication campaign targeting a competing influenza vaccine. The probe centers on allegations that Sanofi disseminated misleading information about Fluad, an enhanced flu vaccine marketed by CSL Seqirus, while promoting its own vaccine, Efluelda, in Germany and France. This action follows unannounced inspections conducted at Sanofi's premises in September 2025.

Commission Raises Concerns Over Messaging Campaign

According to the Commission, Sanofi may have portrayed Fluad as inferior to Efluelda despite recommendations from health authorities supporting the rival vaccine for vulnerable patients with risk factors. The investigation focuses primarily on communications directed at healthcare professionals in Germany and France, markets where the Commission preliminarily believes Sanofi holds a dominant position.

Regulators are examining several aspects of Sanofi's messaging, including claims that the scientific evidence supporting Fluad was weaker than that underpinning Efluelda. Officials are also reviewing whether Sanofi provided misleading or inaccurate interpretations of national vaccination recommendations. In Germany, the Commission is further scrutinizing claims suggesting that recommendations supporting Fluad remained subject to unresolved scientific objections from medical professional societies.

Potential Violation of EU Competition Rules

If the allegations are substantiated, the conduct could constitute an abuse of a dominant market position. Alongside the proceedings, regulators issued a Preliminary Assessment outlining the facts and competition concerns identified so far. Sanofi now has the opportunity to propose commitments aimed at addressing those concerns.