Mylan & Biosimilar Coalition v. Regeneron: Federal Circuit Affirms 13 Aflibercept Patents Unpatentable
A coalition of seven biosimilar developers — including Mylan, Amgen, Biocon, Formycon, Celltrion, and Samsung Bioepis — successfully challenged 13 Regeneron patents covering aflibercept manufacturing and formulation. The Federal Circuit affirmed the unpatentability ruling in January 2025, removing key IP barriers across the high-stakes anti-VEGF biologics market.
Seven-party biosimilar coalition dismantles Regeneron’s aflibercept patent fortress
Filed in June 2024, Case 24-2019 arrived at the Federal Circuit as an appeal by Regeneron Pharmaceuticals seeking to overturn unpatentability findings across a portfolio of 13 US patents. Those patents spanned the full commercial lifecycle of aflibercept — marketed as Eylea — covering anti-VEGF protein compositions, CHO cell integration sites, biological contaminant detection, chemically defined media manufacturing, formulation stability, and methods of treating angiogenic eye disorders including wet age-related macular degeneration.
The Federal Circuit issued its order on January 29, 2025, affirming the unpatentability determination in full. The court found no reversible error in the rulings below, leaving all 13 patents invalidated. For the biosimilar coalition — Mylan, Amgen, Amgen USA, Biocon Biologics, Formycon AG, Celltrion, and Samsung Bioepis — the affirmance clears a substantial portion of the IP thicket surrounding aflibercept biosimilar development and commercialisation.
The 215-day resolution timeline is notably swift for a Federal Circuit appeal of this complexity, suggesting the panel found the unpatentability arguments well-grounded and the record below sufficient to sustain across all 13 patents without extended briefing controversy. What remains unknown from the public record is whether Regeneron will seek en banc reconsideration or petition the Supreme Court, and whether any licensing negotiations are proceeding in parallel given the commercial scale of the Eylea franchise.
Filing to Unpatentable in 215 days
215-day appellate resolution — faster than the median Federal Circuit appeal timeline of ~24 months
Federal Circuit affirms: what the unpatentability ruling means for both parties
What ‘AFFIRMED’ means when 13 patents are at stake
An appellate affirmance signals that the Federal Circuit reviewed the lower unpatentability rulings and found no reversible legal error — factual findings, claim construction, and obviousness or written-description analyses all survived scrutiny. The affirming court does not retry the case; it asks whether the decision below was legally sound. With 13 patents affirmed unpatentable in a single order, this represents a sweeping endorsement of the challenger coalition’s invalidity positions across multiple patent families.
No reversible error foundRegeneron loses its appellate lifeline for all 13 patents
Affirmance at the Federal Circuit exhausts Regeneron’s standard appellate path for these patents. The unpatentability findings are now final unless Regeneron pursues an en banc petition or, in extraordinary circumstances, a Supreme Court certiorari petition. All 13 patents — covering core manufacturing, formulation, and therapeutic use claims for aflibercept — are invalidated, significantly weakening Regeneron’s ability to block or delay biosimilar market entry through this IP portfolio.
IP barrier removedBiosimilar coalition gains cleared IP landscape for aflibercept
For Mylan, Amgen, Biocon, Formycon, Celltrion, and Samsung Bioepis, the affirmance removes 13 patent obstacles spanning compositions, CHO cell systems, manufacturing media, and ophthalmic formulations. Each company’s regulatory and commercial pathway for an aflibercept biosimilar is materially less encumbered. The ruling also strengthens their negotiating position on any remaining Regeneron IP and reduces exposure to future infringement claims based on these now-invalidated patents.
Pathway clearedEylea’s biosimilar market opens; anti-VEGF competition intensifies
Aflibercept generates multi-billion-dollar annual revenues for Regeneron. With 13 manufacturing, formulation, and therapeutic patents now unpatentable, the IP thicket protecting Eylea is substantially reduced. Multiple well-capitalised biosimilar developers are now better positioned to compete on price and access in the wet AMD and diabetic retinopathy treatment market. The ruling may also signal heightened Federal Circuit scrutiny of biologics patent portfolios assembled across overlapping manufacturing process and formulation claims.
Biosimilar competition acceleratesFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Mylan, NV | Company | Biosimilar developer coalition — challengers of Regeneron’s aflibercept patent portfolioSearch in Eureka ↗ |
| Co-Plaintiff | Amgen, Inc. | Company | Search in Eureka ↗ |
| Co-Plaintiff | Biocon Biologics, Inc. | Company | Search in Eureka ↗ |
| Co-Plaintiff | FORMYCON AG | Company | Search in Eureka ↗ |
| Co-Plaintiff | Celltrion, Inc. | Company | Search in Eureka ↗ |
| Co-Plaintiff | Amgen USA, Inc. | Company | Search in Eureka ↗ |
| Co-Plaintiff | Samsung Bioepis Co., Ltd. | Company | Search in Eureka ↗ |
| Defendant | Regeneron Pharmaceuticals, Inc. | Company | Regeneron Pharmaceuticals, Inc. — originator and patent holder of aflibercept (Eylea) biologicsSearch in Eureka ↗ |
| Defendant counsel | Adam Pan | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Andrew V. Trask | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Arthur John Argall, III | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Christian GladdenSorensen | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | David I. Berl | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Elizabeth Weiswasser | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Jacob Hartman | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Kathryn Schleckser Kayali | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Priyata Patel At | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Rhochelle Krawetz | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Shaun Patrick Mahaffy | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Thomas S. Fletcher | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant law firm | Kellogg, Hansen, Todd, Figel & Frederick, PLLC | Law Firm | Representing Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant law firm | Paul, Weiss, Rifkind, Wharton & Garrison LLP | Law Firm | Representing Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant law firm | Williams & Connolly LLP | Law Firm | Representing Regeneron 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 Federal Circuit’s order — ‘THIS CAUSE having been considered, it is ORDERED AND ADJUDGED: AFFIRMED’ — is a summary affirmance of broad scope, applying to all 13 challenged patents simultaneously. At the appellate level, affirmance means the panel found the unpatentability determinations below were not infected by legal error under the applicable standard of review: substantial evidence for factual findings and de novo review for claim construction. The absence of a detailed written opinion, if confirmed, would make this affirmance harder to distinguish in future proceedings, effectively entrenching the unpatentability findings across the full aflibercept manufacturing and formulation patent family.
US9222106B2 and 12 further patents — aflibercept anti-VEGF biologics portfolio
The 13 patents at issue span multiple technical layers of the aflibercept product lifecycle. US9222106B2 and related patents protect anti-VEGF protein compositions and manufacturing methods; US9816110B2 and related assets cover CHO cell integration sites critical for recombinant expression yield; US9254338B2 addresses biological contaminant detection; and several patents, including US10415055B2 and US10669594B2, govern chemically defined media manufacturing and variant reduction. Formulation patents including US11253572B2 protect intravitreal delivery characteristics specific to ophthalmic administration.
This portfolio was strategically assembled to create a multi-layer IP barrier around Eylea, Regeneron’s flagship anti-VEGF biologic, which has generated over $4 billion annually at peak. By covering upstream cell line engineering, midstream manufacturing process parameters, and downstream formulation characteristics, the portfolio was designed to complicate biosimilar development at every stage. The Federal Circuit’s affirmance of unpatentability across all 13 patents signals that such layered portfolio strategies in biologics face serious invalidity risk when challenged by well-resourced coalitions with access to prior art spanning CHO cell biology, protein chemistry, and ophthalmic formulation science.
Should you run an FTO against Regeneron’s surviving aflibercept patent estate?
Any company developing, manufacturing, or commercialising an aflibercept biosimilar — or a competing anti-VEGF biologic for ophthalmic indications — should conduct a targeted FTO analysis against Regeneron’s remaining patent estate. While 13 patents have been affirmed unpatentable, Regeneron holds a large portfolio of continuation applications and divisional filings in CHO expression, formulation chemistry, and therapeutic use. Published applications and granted patents not captured in this litigation may still present infringement exposure, particularly for second-generation or higher-concentration aflibercept formulations.
PatSnap Eureka’s FTO Search Agent can map the full Regeneron aflibercept patent family — including continuations, divisionals, and foreign counterparts — against your specific product claims and manufacturing process. By cross-referencing the 13 now-invalid patents with surviving related claims, Eureka identifies where genuine FTO clearance exists and where file-history estoppel or continuation claims may recreate risk. This is particularly valuable for Biocon, Formycon, and Samsung Bioepis teams preparing regulatory submissions in markets where Regeneron’s counterpart patents may still be in force.
Run a freedom-to-operate analysis on US9222106B2 to assess your product’s exposure
Run FTO in Eureka →Similar Federal Circuit biosimilar patent invalidity appeals
Cases involving Federal Circuit review of multi-patent invalidity challenges to anti-VEGF and ophthalmic biologics manufacturing portfolios — most relevant to biosimilar IP strategy.
What this case signals for the anti-VEGF biologics IP landscape
The affirmance of 13 unpatentability rulings in a single Federal Circuit order sets a meaningful precedent for how courts evaluate layered biologics patent portfolios.
Broad manufacturing patent portfolios face elevated invalidity risk at the Federal Circuit
Regeneron’s strategy of layering patents across compositions, CHO expression systems, manufacturing media, and formulation did not survive coordinated IPR challenge. Biologics innovators should audit portfolios for written description and obviousness vulnerabilities before biosimilar ANDA or BLA filings trigger inter partes review.
Coalition-based patent challenges amplify pressure on originator portfolios
Seven parties joining as co-challengers creates both financial and evidentiary momentum that single-challenger IPRs may not replicate. R&D and legal teams planning biosimilar entry should evaluate whether consortium challenge structures lower individual litigation risk while improving invalidity record quality across multiple patent families.
Mylan v Regeneron — key questions answered
The Federal Circuit affirmed unpatentability findings across all 13 Regeneron patents covering aflibercept compositions, CHO expression systems, manufacturing methods, and ophthalmic formulations. The order, issued January 29, 2025, found no reversible error in the rulings below, invalidating patents including US9222106B2, US11084865B2, US9816110B2, and ten further related assets.
The plaintiff coalition comprised Mylan NV, Amgen Inc., Amgen USA Inc., Biocon Biologics Inc., Formycon AG, Celltrion Inc., and Samsung Bioepis Co. Ltd. — seven companies jointly challenging Regeneron’s aflibercept patent portfolio at the Federal Circuit.
The 13 patents covered anti-VEGF protein compositions and production methods, CHO cell integration sites, biological contaminant detection, enhanced expression and stability regions, methods for producing aflibercept in chemically defined media, VEGF antagonist use for angiogenic eye disorders, and intravitreal formulations — spanning the full manufacturing and therapeutic lifecycle of aflibercept (Eylea).
In this context, ‘unpatentable’ as the basis of termination indicates that the underlying proceedings — likely inter partes review petitions at the Patent Trial and Appeal Board — determined the challenged claims failed to meet patentability requirements, and the Federal Circuit’s affirmance confirms those determinations stand as final.
Following a Federal Circuit affirmance, Regeneron’s remaining options are limited: it may petition for en banc rehearing before the full Federal Circuit, or seek certiorari from the US Supreme Court — both are discretionary and rarely granted. The commercial and strategic implication is that these 13 patents should be treated as finally invalidated for biosimilar launch planning purposes, absent extraordinary further proceedings.
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