Patients with Pompe disease in the United States and Europe are reporting delayed shipments of the enzyme infusions that keep the condition from progressing, and the manufacturer has confirmed that the supply of two products is constrained.
Sanofi is facing shortfalls of Myozyme and Nexviazyme, according to reporting by STAT, which described a bottleneck in the final manufacturing phase along with quality control problems at the company's plant in Waterford, Ireland. The site handles batch release, the final quality assurance step before a manufactured lot can be shipped.
A Sanofi spokesman said the impact "varies by country and by product," depending on available inventory, local demand and the timing of upcoming shipments, adding that delays are limited in some markets. The company has indicated it could take months before production has sufficiently resumed and stabilized, and longer still before normal inventories are rebuilt.
The Sequence, Stated Carefully
The shortage follows a regulatory action, and the relationship between the two has not been established.
In June of this year, the FDA issued a warning letter after a January inspection of the Waterford facility. According to STAT's reporting, that letter concerned violations involving production of other medicines. Sanofi has stated publicly that product released from the facility meets established quality and safety specifications.
What is confirmed is timing and location, not causation. A regulatory citation at a plant and a supply constraint involving products that pass through that plant are two documented facts in close proximity. Whether one produced the other has not been demonstrated by any agency finding available at this point.
Patient groups including the Acid Maltase Deficiency Association, Pompe Alliance and the Pompe Warrior Foundation have said the delays reported to them involve some Nexviazyme shipments. They have not received confirmation that Lumizyme, the brand under which alglucosidase alfa is marketed in the United States, is currently affected, and have advised patients on either therapy to verify upcoming shipments. Those organizations have characterized the situation as a product release and distribution timing problem rather than evidence of a safety or quality issue with medication already released.
Why an Interrupted Infusion Is Not a Missed Pill
Pompe disease is a rare inherited condition caused by a deficiency of acid alpha-glucosidase, an enzyme that breaks down glycogen. Without enough of it, glycogen accumulates inside muscle cells and damages them, affecting skeletal muscle, the diaphragm and, in the infantile-onset form, the heart.
Enzyme replacement therapy delivers a laboratory-made version of the missing enzyme by intravenous infusion, typically every two weeks. It is the only disease-modifying treatment class available. It does not cure the condition and it does not build a reserve. It works by continuously clearing glycogen that keeps accumulating.
That biology is why interruption matters differently here than for many chronic medications. Muscle damage from glycogen buildup is not reliably reversible. Untreated infantile-onset disease, the most aggressive form, can lead to heart failure and death within the first year of life, so the margin there is narrowest. In late-onset disease, progression is slower, and the concern with a gap is loss of respiratory and mobility function that may not be regained.
Nexviazyme was approved in the United States in 2021 for late-onset Pompe disease in patients one year and older. Alglucosidase alfa was first approved in 2006.
The Households Carrying the Most Uncertainty
Risk in a shortage is not evenly distributed, and here it tracks fairly closely to disease severity and to logistics.
Infants and young children with infantile-onset disease face the tightest clinical timeline. Adults with advanced late-onset disease who depend on ventilatory support or have limited respiratory reserve have the least room for functional loss. Patients newly starting therapy may find initiation postponed, since existing supply is generally prioritized to people already established on treatment.
There are practical burdens layered on top. Infusions are administered in hospital outpatient centers, infusion suites or at home by a nursing service, each of which requires scheduling weeks ahead. A delayed shipment can mean a canceled infusion slot, unpaid time off work for a caregiver, and a rescheduling queue. Families who travel for treatment absorb transportation costs twice.
Alternative options exist but are not interchangeable. Cipaglucosidase alfa administered with oral miglustat is an approved alternative for some adults with late-onset disease, and switching involves clinical judgment about disease stage, prior response and antibody status. It is not a decision to make around a shipment delay.
Steps for Patients and Caregivers Now
Nobody should change or stop enzyme replacement therapy without speaking to their prescribing team. That is the single most important point, and it applies regardless of what a shipment notification says.
The useful action is to contact the specialty pharmacy or infusion center and confirm the next scheduled shipment and infusion date specifically, rather than assuming the schedule holds. If a shipment is delayed, the treating metabolic or neuromuscular specialist should be told promptly, because the clinical team decides how to sequence available doses and whether any interim option applies.
Patients can also ask their center whether it participates in any manufacturer allocation process and whether Sanofi's patient support program has current information for their product. Documenting each delayed or canceled infusion with dates helps if insurance authorization windows or prior approvals lapse during the gap.
Symptoms that warrant prompt medical contact rather than waiting include new or worsening shortness of breath, difficulty lying flat, increased daytime sleepiness or morning headache, which can signal declining respiratory function, along with new swallowing difficulty or a noticeable drop in strength or mobility.
Neither the FDA nor Sanofi has published a resolution date, and neither product appears in the FDA drug shortage database as of this writing. MedicalDaily will report any formal shortage listing, allocation guidance or update on the Waterford facility's status.
Key Questions Answered
Which treatments are affected? Supply constraints have been reported for Myozyme and Nexviazyme. Patient organizations say the delays reported to them involve some Nexviazyme shipments.
Did the FDA warning letter cause the shortage? That has not been established. The FDA issued a warning letter in June following a January inspection, and reporting indicates it concerned production of other medicines. Sanofi says released product meets specifications.
Is medication already dispensed unsafe? No agency or company statement indicates a safety problem with product already released.
Why does missing infusions matter? Enzyme replacement works by continuously clearing glycogen buildup. Muscle damage from accumulation is not reliably reversible.
Who faces the greatest risk? Infants with infantile-onset disease and adults with advanced late-onset disease, particularly those with limited respiratory reserve.
Should a patient switch to another therapy? Not without specialist input. Switching involves clinical judgment about disease stage, prior response and antibody status.
What should patients do this week? Contact the specialty pharmacy or infusion center to confirm the next shipment and infusion date, and notify the treating specialist of any delay.
