One Irish Plant Releases Both of Sanofi's Pompe Enzymes. In June, the FDA Called Its Drugs 'Adulterated.'

When someone tells me a drug is in short supply, my first assumption is that the world ran out of something hard to make. A rare cell line stopped growing. An ingredient got stuck on a boat. That kind of shortage I can live with, because it is nobody’s fault and nobody could have prevented it.

That is not what happened to Pompe patients this month. The enzyme is not missing. Sanofi told the International Pompe Association on August 7 that the constraint is not a shortage of the drug substance at all, but a bottleneck in the final manufacturing, quality-control and batch-release steps. The substance exists. It is sitting in the plant. What is jammed is the last stretch, the step that turns a vat of enzyme into vials a nurse can push into a vein. And the plant that runs that final release is the same Waterford site the FDA had just cited for making “adulterated” drugs. That is the sentence that made me put my coffee down.

Let me back up, because if you do not know Pompe disease, “your infusion might be a couple of weeks late” sounds survivable. For a Pompe patient it is not.

Pompe is a lysosomal storage disorder. You inherit two broken copies of the gene for an enzyme called acid alpha-glucosidase, and that enzyme has one job: it lives in the lysosome, the cell’s little recycling chamber, and it breaks down glycogen, the body’s stored form of sugar. Take the enzyme away and the glycogen has nowhere to go. It pours in and piles up, and it piles up worst in the tissues that never get to rest: the heart, the skeletal muscle, and the diaphragm, the sheet of muscle that drives every breath you take. The Muscular Dystrophy Association describes the endpoint without softening it: muscle deterioration, then respiratory or cardiac failure.

There is no one-and-done fix here, no gene therapy waiting on a shelf for these patients. The two treatments, Myozyme/Lumizyme and its second-generation successor Nexviazyme (the enzyme engineered to get pulled into muscle more efficiently), do not repair anything. They are a resupply. You infuse the missing enzyme, it slips into the cells, it reaches the lysosome, it clears the glycogen that has built up since last time. Then it degrades, and the glycogen starts creeping back, so you do it again. Every two weeks. For the rest of your life.

Two weeks is not a lot of slack. For most medications, “distribution timing” is an annoyance. For a Pompe patient, a late shipment is glycogen quietly resuming its climb in the diaphragm while the fix sits in a warehouse in Ireland. And here is where I lose patience with the reassuring language, because the reassurance is technically accurate and completely beside the point. Nobody is worried the released vials are unsafe. They are worried the vials are not coming.

So what did the FDA actually find? The agency inspected the Waterford site for nine days in January and, on June 22, issued Warning Letter CBER 26-728681 to Genzyme Ireland Limited, the Sanofi subsidiary that runs the plant. Per the Irish Times, that subsidiary booked €1.65 billion in revenue and €328.5 million in pretax profit in 2024 and employs more than 950 people. This is not a scrappy, underfunded operation. And the FDA used the word that ends careers in this industry: the products were “adulterated,” meaning the manufacturing did not meet good-manufacturing-practice standards. The quality unit did not keep complete lab records. And the finding I cannot stop turning over: the firm cancelled numerous deviations without investigating the root cause or assessing product impact.

Sit with that for a second. A “deviation” is the report a plant files when something goes wrong on the line. Cancelling them without investigating is not a filing error. It is a quality culture deciding it would rather not know.

The warning letter named two other products, the transplant drug Thymoglobulin and the hemophilia therapy Altuviiio, not the Pompe enzymes. But the Pompe drugs move through the same final release process at the same site, and that process is exactly what Sanofi now says is the bottleneck. The IPA update is explicit that Waterford handles the batch release for both Myozyme and Nexviazyme. So the extra quality-control steps the plant now has to run to satisfy the FDA are the same steps standing between made enzyme and a patient’s arm. The company reassuring Pompe patients is the same company whose plant the FDA just cited.

The record is still incomplete, and I want to be straight about that: no one has published a count of patients who have actually missed a dose, Nexviazyme delays are confirmed while the US Lumizyme picture is still unclear, and the impact runs unevenly from one country to the next. But the documents already show the shape of it. The batch release for both of a fatal disease’s only two enzymes runs through one Irish plant; that plant just failed an FDA inspection on the exact step now jammed; and the same company that says the drug substance is fine also told the IPA the fix could take months. Patient groups, including the Acid Maltase Deficiency Association, are telling members to call Sanofi and confirm their next shipments in writing.

The reassurance and the receipts do not line up, and when they do not, I trust the receipts.

If it were me, or someone I love, on this drug, I would not wait to be told it is fine. I would do exactly what the patient groups are urging: get on every Sanofi notification list, confirm the next two shipments in writing, and sit down with my Pompe specialist about a contingency now, while there is still slack, not after a dose is already at risk. The one thing every group agrees on is the one thing I would hold onto hardest, which is do not skip or change an infusion on your own. And I would stop accepting “it is only a timing problem” from the company whose timing is the problem.

Sources

1. STAT – A shortage of two Sanofi medicines for Pompe disease rattles patients (Aug 9, 2026)
2. FDA – Warning Letter CBER 26-728681, Genzyme Ireland Limited (June 22, 2026)
3. International Pompe Association – Global supply constraints continue for Sanofi’s Pompe therapies (Aug 7, 2026)
4. Irish Times – Irish pharma company making ‘adulterated products’, US regulator claims (July 2, 2026)
5. Acid Maltase Deficiency Association – Reports of Nexviazyme shipment delays
6. Muscular Dystrophy Association – FDA approval of Nexviazyme for Pompe disease