Regeneron v. Allele Biotechnology: Federal Circuit Appeal Voluntarily Dismissed
Regeneron Pharmaceuticals and Allele Biotechnology jointly agreed to dismiss their Federal Circuit appeal over US10221221B2, a patent covering monomeric yellow-green fluorescent protein derived from cephalochordate. The case closed just 67 days after filing, with each party bearing its own costs — a resolution that raises questions about the underlying commercial dynamic.
A swift Federal Circuit exit over a fluorescent protein patent
Regeneron Pharmaceuticals, Inc. filed this appeal at the United States Court of Appeals for the Federal Circuit on 25 October 2024, bringing an infringement action against Allele Biotechnology and Pharmaceuticals, Inc. concerning US10221221B2. That patent, filed under application number US13/950239, covers a monomeric yellow-green fluorescent protein derived from cephalochordate — a class of marine invertebrates — with significant utility as a biological research and imaging tool.
The appeal was terminated on 31 December 2024 by voluntary dismissal under Federal Rule of Appellate Procedure 42(b), on the agreed motion of both parties. The court ordered that each side bear its own costs, meaning neither party received a cost-shifting award. Because the dismissal was voluntary and the public record does not specify whether it was with or without prejudice, the precise procedural posture of the underlying infringement claims remains unclear from public filings alone.
The 67-day lifespan of this appeal is notably short for Federal Circuit proceedings and suggests the parties reached agreement — whether through settlement, licence, or a strategic decision to abandon the appeal — shortly after filing. The speed of resolution and the mutual cost-bearing arrangement are consistent with a negotiated outcome, though the specific terms, if any, are not disclosed in the public record.
Filing to Voluntary dismissal in 67 days
67 days — well below the median Federal Circuit appeal duration of ~18 months, suggesting early agreement
Appeal voluntarily dismissed: what the Fed. R. App. P. 42(b) exit means for both parties
Fed. R. App. P. 42(b): a consensual appellate exit
Rule 42(b) of the Federal Rules of Appellate Procedure permits parties to dismiss an appeal by filing a signed agreement. Unlike a merits ruling, a Rule 42(b) dismissal issues no finding on infringement, validity, or claim scope. The court acts ministerially on the parties’ agreement. This means the appeal record creates no precedential guidance on US10221221B2 or the underlying fluorescent protein technology.
No merits adjudicationWith or without prejudice? The public record is silent
When a voluntary dismissal does not specify prejudice terms, practitioners must treat the status of the underlying claims as unresolved. A dismissal without prejudice would leave Regeneron free to re-assert US10221221B2 in future proceedings; one with prejudice would bar re-litigation. The docket entry here does not specify either, meaning the enforceability posture of the patent against Allele Biotechnology cannot be definitively assessed from public filings alone.
Prejudice terms undisclosedRegeneron exits the Federal Circuit without a ruling
As the party that initiated the appeal, Regeneron agreed to its dismissal within 67 days. This is consistent with either a favourable private resolution — such as a licence or settlement — or a strategic reassessment of appellate prospects. Without a merits ruling, Regeneron’s patent US10221221B2 remains in force but untested at the Federal Circuit level on the specific infringement questions raised in this proceeding.
No Federal Circuit precedent setAllele Biotechnology avoids an adverse ruling at the appellate level
For Allele Biotechnology, the voluntary dismissal ends Federal Circuit exposure without a finding of infringement. Whether this reflects a confidential licence, a design-around, or simply Regeneron’s withdrawal is not public. The cost-neutral order — each side bears its own costs — suggests the dismissal was genuinely mutual rather than imposed, and Allele faces no financial penalty from this proceeding.
No infringement findingFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Regeneron Pharmaceuticals, Inc. | Company | Biopharmaceutical company — holder of US10221221B2, monomeric fluorescent protein patentSearch in Eureka ↗ |
| Defendant | Allele Biotechnology and Pharmaceuticals, Inc. | Company | Biotechnology company specialising in fluorescent protein tools and reagents for researchSearch in Eureka ↗ |
| Plaintiff counsel | Alyssa A. Dolan | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Arlene L. Chow | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | David Frazier | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Gabriel K. Bell | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Michael A. Morin | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Michelle Ernst | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Will Orlady | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Latham & Watkins, LLP | Law Firm | Representing Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Andrew Dufresne | Attorney | Counsel for Allele Biotechnology and Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Christopher Graydon Wayne Hanewicz | Attorney | Counsel for Allele Biotechnology and Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | David Lee Anstaett | Attorney | Counsel for Allele Biotechnology and Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant law firm | Perkins Coie LLP | Law Firm | Representing Allele Biotechnology and Pharmaceuticals, Inc.Search in Eureka ↗ |
| Presiding judge | Judge N/A | Judge | Court of Appeals for the Federal CircuitSearch in Eureka ↗ |
Official order — verbatim text
The dismissal order is minimal by design: it records the parties’ agreement, invokes Rule 42(b), and allocates costs neutrally. The absence of any merits language means the order provides no claim construction, no validity finding, and no infringement determination. For practitioners, the ‘each side bears its own costs’ formulation is consistent with a negotiated exit rather than a unilateral withdrawal, suggesting both parties had reason to resolve the matter without a Federal Circuit ruling.
US10221221B2 — Monomeric yellow-green fluorescent protein from cephalochordate
US10221221B2, filed under application number US13/950239, protects a monomeric form of yellow-green fluorescent protein isolated or derived from cephalochordate organisms — a phylum of small, filter-feeding marine invertebrates. Monomeric fluorescent proteins are highly valued in biological research because they do not form dimers or oligomers that can perturb the function of fusion partners, making them superior tools for live-cell imaging, protein localisation studies, and FRET-based assays. The patent’s cephalochordate origin is distinctive, as most commercial fluorescent proteins are derived from cnidarians such as jellyfish or coral.
For the biological reagent and research tool sector, US10221221B2 represents a potentially broad proprietary position on a distinct fluorescent protein scaffold. Companies supplying monomeric yellow-green fluorescent proteins or developing fusion constructs based on cephalochordate-derived sequences face meaningful FTO exposure. The fact that Regeneron — a large-cap biopharma with substantial IP enforcement capabilities — holds and has actively litigated this patent elevates the risk profile for any competitor operating in this space without a licence or clear design-around.
Should your team run an FTO against US10221221B2?
Any R&D team or product group working with monomeric yellow-green fluorescent proteins — whether in reagent manufacturing, live-cell imaging kit development, or protein engineering — should assess exposure to US10221221B2. The patent’s cephalochordate-derived scaffold may cover sequences or structural features that are not immediately apparent from product names alone. Given that Regeneron has pursued this patent through Federal Circuit proceedings, the enforcement intent is credible.
PatSnap Eureka’s FTO Search Agent allows you to map your specific protein sequences and construct designs against the claims of US10221221B2 and its family members. Eureka can identify relevant prior art, flag dependent claim risks, and surface any continuations or divisionals that may extend the patent’s effective coverage. Run a targeted FTO now to assess whether your fluorescent protein pipeline requires design modification or a licensing conversation.
Run a freedom-to-operate analysis on US10221221B2 to assess your product’s exposure
Run FTO in Eureka →Similar Federal Circuit appeals involving fluorescent protein and biotech tool patents
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What this case signals for the fluorescent protein IP landscape
A fast Federal Circuit exit over a marine-derived fluorescent protein patent warrants close attention from biotech tool developers and imaging reagent suppliers.
Fluorescent protein patents remain actively enforced at the appellate level
The fact that Regeneron pursued a Federal Circuit appeal — however briefly — over US10221221B2 signals that monomeric fluorescent protein IP is treated as commercially significant. Companies developing or distributing cephalochordate-derived fluorescent protein tools should maintain current FTO clearance against this patent family.
A 67-day voluntary dismissal typically signals a private resolution
Appeals dismissed this rapidly under Rule 42(b) are rarely abandoned for procedural reasons alone. The pattern is consistent with a licensing agreement or settlement reached after the appeal was filed. Competitors watching this space should note that the underlying commercial dispute may have resolved on undisclosed terms that affect market access to the patented protein.
Regeneron v Allele — key questions answered
The Federal Circuit appeal was voluntarily dismissed on 31 December 2024 under Fed. R. App. P. 42(b), by agreement of both parties. No merits ruling on infringement or validity of US10221221B2 was issued. Each side was ordered to bear its own costs. The case lasted just 67 days from filing to closure.
US10221221B2 covers a monomeric yellow-green fluorescent protein derived from cephalochordate marine invertebrates. Monomeric fluorescent proteins are preferred in biological research for live-cell imaging and fusion protein studies because they avoid aggregation artefacts. The cephalochordate origin distinguishes this patent from cnidarian-derived protein patents and may cover a commercially distinct scaffold used in research tool products.
A Rule 42(b) dismissal terminates the appeal by party agreement without any court ruling on the merits. It does not invalidate the patent, limit its claims, or constitute a finding of non-infringement. The public record in this case does not specify whether the dismissal was with or without prejudice, leaving the status of any underlying infringement claims legally ambiguous from publicly available information alone.
The order that each side bear its own costs is consistent with a negotiated resolution, as it reflects a balanced outcome rather than one party conceding defeat. Combined with the 67-day duration — unusually short for a Federal Circuit appeal — this pattern suggests a private agreement may have been reached, though no settlement terms are disclosed in the public docket.
Companies commercialising monomeric yellow-green fluorescent proteins, particularly those based on cephalochordate-derived sequences, face potential infringement exposure under US10221221B2. Regeneron’s active enforcement history at the Federal Circuit level signals credible assertion intent. R&D teams and product managers in the biological imaging and reagent sectors should conduct a targeted freedom-to-operate analysis against this patent and its family before commercialising related products.
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