FDA issued Regeneron a Form 483 on January 16, 2026, at the end of an inspection of its East Greenbush, New York facility that began on December 11, 2025. Its observations have not appeared in any public summary. A 483 is not a final FDA finding. The approvals Regeneron actually lost in 2025 came from inspection findings at a contract filler, not at its own facilities.
Facility data below come from Atlas facility records (release of August 15, 2026): five Regeneron sites, 39 FDA inspections, 13 ending with a Form 483. CRL details come from Regeneron's SEC filings.
The January 2026 Form 483 at East Greenbush
The Atlas record for Regeneron Pharmaceuticals, Inc. in East Greenbush (FEI 3015581066) shows one FDA inspection, a human drugs inspection that ran from December 11, 2025 to January 16, 2026 and ended with a Form 483. Three investigators are tied to it: Cassandra L Abellard, Hamet M Toure and Jiangsong Jiang. It is the first FDA inspection on record for this FEI. FDA's own website also carries a record page titled for Regeneron Pharmaceuticals, Inc., East Greenbush, NY, with the date 1/16/26 and the same FEI number.
The August 15, 2026 Atlas release holds the inspection, its outcome and its investigators, but not the text or count of the observations. We could not find them in FDA posts, trade press or Regeneron's filings; its 2025 10-K and 2026 quarterly reports do not mention a Form 483 or East Greenbush.
Some context helps. Regeneron's job postings for East Greenbush describe maintenance of systems that support drug product filling, visual inspection, device assembly and packaging. A Form 483 records conditions investigators considered objectionable. It does not say how FDA will classify the inspection; that decision comes later, as explained in our guide to NAI, VAI and OAI classifications.
Regeneron's facilities in FDA's records
FDA tracks each facility by FEI number. Atlas holds five Regeneron records.
| Facility | FEI | Inspections | Ended in a 483 | Last inspection | Last outcome |
|---|---|---|---|---|---|
| Rensselaer, New York | 1000514603 | 19 | 9 | Mar 2024 | 483 |
| East Greenbush, New York | 3015581066 | 1 | 1 | Jan 2026 | 483 |
| Tarrytown, New York | 1000521995 | 13 | 1 | Dec 2025 | Clean |
| Armonk, New York | 3026012834 | 1 | 0 | Mar 2026 | Clean |
| Limerick, Ireland (Regeneron Ireland DAC) | 3011684330 | 5 | 2 | Jun 2025 | Clean |
Rensselaer carries most of the history. Nine of its 19 inspections since 2002 ended with a 483, most recently after an inspection from March 13 to 22, 2024. Tarrytown has been inspected 13 times with one 483, in February 2013. All 11 inspections since then were clean, the latest in December 2025. Limerick received 483s in May 2021 and March 2023, then passed its June 2025 inspection clean. Armonk's first inspection, in March 2026, ended without a form.
You can search every record, including look-alike firm names that are not Regeneron, in our FDA-inspected sites directory.
What FDA has cited at Rensselaer
Atlas holds public observation detail for five Rensselaer forms, ten observations in total. The largest is the October 25, 2021 Form 483, issued after an inspection from September 27 to October 25, 2021 by Guerlain Ulysse and Robert J Martin. Its six observations cite four sections:
| CFR section | What it covers | 2021 form | Other Rensselaer forms |
|---|---|---|---|
| 21 CFR 211.113(b) | Procedures and validation to prevent microbial contamination of sterile drug products | 2 | None |
| 21 CFR 211.192 | Investigation of discrepancies and failures, with written records | 2 | None |
| 21 CFR 211.42(c)(10)(v) | Cleaning and disinfecting systems in aseptic processing areas | 1 | None |
| 21 CFR 600.14(c) | Timing of biological product deviation reports to FDA | 1 | None |
| 21 CFR 211.22(d) | Quality unit procedures in writing and followed | 0 | 2014, 2016, 2019 |
| 21 CFR 211.100(b) | Deviations from production procedures recorded and justified | 0 | May 2013 |
Two patterns stand out. The single-observation forms from 2014, 2016 and 2019 each cite 211.22(d), the same quality unit procedure section, three inspections in a row. Then the 2021 form shifts to sterile manufacturing: contamination control, aseptic area cleaning and investigations. The one Tarrytown observation, from February 2013, cites 21 CFR 600.80(b) on procedures for reviewing adverse experience reports.
Atlas does not hold the observation text for the March 2024 Rensselaer form, nor for the 2010, 2011 and 2015 forms. Those inspections are on record with a 483 outcome, without public detail.
AtlasSee what the FDA knows about your next investigator.
30 minutes with the founder. No pitch deck.
The complete response letters FDA tied to a filler inspection
Regeneron's approval delays in 2025 trace to Catalent Indiana LLC in Bloomington, a contract filler that Novo Nordisk acquired. The sequence, from Regeneron's filings:
- August 1, 2025. In its second quarter 2025 results, Regeneron said three pending EYLEA HD applications (the pre-filled syringe, every-four-week dosing, and macular edema after retinal vein occlusion), each with an August 2025 action date, would be delayed by observations from an FDA general site inspection at Catalent Indiana completed in mid-July. The same release reported a complete response letter on July 30, 2025 for odronextamab in relapsed or refractory follicular lymphoma, also affected by that inspection.
- October 2025. In its third quarter 2025 results, released October 28, Regeneron said Catalent had received an OAI letter citing unresolved issues from the July inspection, and that FDA had issued a CRL the day before for the pre-filled syringe supplemental BLA. The sole approvability issue in that letter was the unresolved inspection findings at Catalent.
- November 20, 2025. FDA sent Catalent Indiana a warning letter based on the June 23 to July 14, 2025 inspection. Its first citation is 21 CFR 211.192, inadequate investigations, including more than 20 deviations since August 2023 tied to mammalian hair in or around vial stoppers, and media fill terminations that were never investigated.
- December 2025 to April 2026. Regeneron's fourth quarter 2025 results reported that FDA approved a new manufacturer to fill EYLEA HD vials in December 2025, approved EYLEA HD for macular edema after retinal vein occlusion and monthly dosing flexibility, and received an application for a new pre-filled syringe filler. Its first quarter 2026 release said it had also resubmitted for syringe filling at Catalent Indiana after an FDA re-inspection there.
- July 2026. Regeneron's second quarter 2026 report says the company is working with FDA and multiple third-party fillers toward approval of the pre-filled syringe by the end of 2026.
This was not the first time. In June 2023, Regeneron said a CRL for aflibercept 8 mg followed an ongoing review of inspection findings at a third-party filler, and trade press tied it to a three-observation Form 483 at Catalent's Bloomington facility. In August 2024, a CRL for linvoseltamab in multiple myeloma cited findings from a pre-approval inspection at a third-party fill and finish provider, made for another company's product candidate.
None of these letters cited a Regeneron facility. Regeneron's 10-Q states it plainly: it has received several CRLs because of FDA's findings at third-party manufacturers responsible for filling drug product.
Where Regeneron fits in the wider CRL data
Facility problems are common in rejected applications. In the Atlas complete response letter analysis, built from letters FDA has published, FDA issued 65 CRLs in 2024, 48 in 2025 and 17 from January to June 2026. Of the 65 letters from 2024, 42 cited facility inspection issues. The 2024 letters split 44 for NDAs and 21 for BLAs.
Regeneron's odronextamab and EYLEA HD syringe letters are BLA cases where the facility, not the clinical package, was the stated problem. A contract filler's general site inspection can hold every application that names it; Regeneron noted the July 2025 inspection was not specific to EYLEA HD.
What quality teams can take from Regeneron's record
Your filler's inspection is your inspection. One OAI at a shared fill and finish site stalled an oncology BLA and three ophthalmology applications. Know the last outcome of every contract site named in a pending application.
A second filler is a regulatory asset. Regeneron's way out was adding vial and syringe fillers through new applications, each with its own review clock.
Repeat citations get noticed. The same quality unit section on three Rensselaer forms in a row is the kind of pattern an investigator reads before walking in. Our guide to preparing for pre-approval inspections covers how to close those out before the next visit.
The 483 response window still matters. FDA considers a written response received within 15 business days of the inspection close before deciding on further action, so for East Greenbush that window closed in early February. How that window works is covered in our piece on the 483 versus warning letter response window.
AtlasFDA Inspection Intelligence Digest
We track every 483, EIR, and warning letter the moment it happens. Get the signals before they hit the FDA website.
Frequently asked questions
The observations from the January 16, 2026 Form 483 are not in any public summary we could verify, and Regeneron has not described them in its SEC filings. What is on record is the inspection itself: December 11, 2025 to January 16, 2026, a human drugs inspection with three investigators, ending with a Form 483. The classification of the inspection has not been published.
Written by
Bhavish Agarwal
Founder, Atlas
Bhavish Agarwal is the founder of Atlas and previously worked at Google and Microsoft. He has spent the past several years building regulatory data infrastructure for the pharmaceutical industry.
