Regeneron v. Mylan et al. (24-2351): Federal Circuit Affirms Aflibercept Patent Portfolio
Regeneron Pharmaceuticals secured a Federal Circuit affirmance of its 13-patent aflibercept portfolio against seven biosimilar defendants — including Mylan, Amgen, Biocon, Celltrion, Samsung Bioepis, Sandoz, and Formycon — in a sweeping infringement action resolved in 171 days. The ruling reinforces Regeneron’s exclusivity position over its blockbuster anti-VEGF biologic Eylea and its underlying manufacturing platform.
Federal Circuit locks in Regeneron’s 13-patent aflibercept fortress against seven biosimilar challengers
Filed on 24 September 2024, Case No. 24-2351 brought Regeneron Pharmaceuticals before the U.S. Court of Appeals for the Federal Circuit to defend 13 patents covering the full lifecycle of aflibercept — from CHO cell-line expression and integration sites to anti-VEGF protein composition, reduced-variant manufacturing in chemically defined media, and intravitreal formulations. Seven biosimilar developers — Mylan Pharmaceuticals, Amgen, Amgen USA, Biocon Biologics, Formycon AG, Celltrion, and Samsung Bioepis, alongside Sandoz — collectively contested the lower court’s findings in an infringement action.
The Federal Circuit issued its decision on 14 March 2025, explicitly affirming the lower court ruling in full. The court considered Regeneron’s remaining arguments — suggesting some arguments were already addressed in prior proceedings — and found them unpersuasive, rendering a clean ‘AFFIRMED’ disposition. For the seven biosimilar defendants, the affirmance exhausts the appellate avenue at this court level, leaving the lower court’s infringement and validity findings intact and enforceable.
The 171-day resolution is notably compressed for a Federal Circuit appeal of this complexity, involving 13 patents across multiple technical domains and seven sophisticated defendants. The breadth of the patent portfolio — spanning upstream manufacturing, cell-line biology, protein analytics, and downstream formulation — suggests Regeneron pursued a layered exclusivity strategy designed to be difficult to design around. What the public record does not disclose is the precise claim scope adjudicated, whether any patents were narrowed during prosecution or reexamination, or the specific grounds the court found unpersuasive.
Filing to Appeal Dismissed in 171 days
171-day appeal — faster than the Federal Circuit median of ~18 months, suggesting resolution on existing record
Federal Circuit affirms: what the ruling means for both parties
Affirmance means the lower court found no reversible error
When the Federal Circuit ‘affirms,’ it confirms that the tribunal below committed no reversible legal or factual error sufficient to disturb its judgment. The appellate court reviews patent claim construction de novo and factual findings for clear error. Here, the court explicitly considered Regeneron’s remaining arguments and rejected them, signalling that the lower court’s infringement and validity determinations were well-supported on the record.
No reversible error foundRegeneron’s 13-patent aflibercept exclusivity wall stands
For Regeneron, the affirmance means its entire asserted patent portfolio remains enforceable as adjudicated. Each of the 13 patents — covering manufacturing processes, CHO integration sites, contaminant detection, formulation, and therapeutic use — retains its scope. Biosimilar market entry routes that the defendants sought to establish remain legally blocked, preserving Regeneron’s commercial position in the anti-VEGF space through the remaining patent terms.
All 13 patents enforceableSeven biosimilar defendants exhaust Federal Circuit appeal path
For Mylan, Amgen, Biocon, Celltrion, Samsung Bioepis, Sandoz, and Formycon, the Federal Circuit affirmance closes the standard appellate route at this level. Further challenge would require a petition for certiorari to the U.S. Supreme Court — a high bar — or re-engagement via inter partes review at the USPTO on different grounds. Any of the seven defendants remaining in the biosimilar race for aflibercept must now pursue regulatory or design-around strategies rather than litigation-based clearance.
Appellate options exhausted hereLayered patent portfolio strategy validated for biologics
The affirmance of 13 patents spanning manufacturing, cell biology, analytics, and formulation sets a precedent confirming that layered, platform-level patent portfolios can collectively withstand a coordinated multi-defendant challenge. For the biosimilar sector, it raises the IP bar significantly: future anti-VEGF biosimilar developers must contend with a validated fortress portfolio. For innovators in the biologic space, this outcome consistently suggests aggressive upstream and downstream patent prosecution is a commercially durable strategy.
Fortress portfolio strategy validatedFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Regeneron Pharmaceuticals, Inc. | Company | Biopharmaceutical innovator — holder of US9222106B2 and 12 aflibercept patentsSearch in Eureka ↗ |
| Defendant | Mylan Pharmaceuticals, Inc. | Company | Seven biosimilar developers including Mylan, Amgen, Biocon, Celltrion, Samsung Bioepis, Sandoz & FormyconSearch in Eureka ↗ |
| Co-Defendant | Amgen, Inc. | Company | Search in Eureka ↗ |
| Co-Defendant | Biocon Biologics, Inc. | Company | Search in Eureka ↗ |
| Co-Defendant | FORMYCON AG | Company | Search in Eureka ↗ |
| Co-Defendant | Celltrion, Inc. | Company | Search in Eureka ↗ |
| Co-Defendant | Amgen USA, Inc. | Company | Search in Eureka ↗ |
| Co-Defendant | Samsung Bioepis Co., Ltd. | Company | Search in Eureka ↗ |
| Co-Defendant | Sandoz, Inc. | Company | Search in Eureka ↗ |
| Plaintiff counsel | Adam Pan | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Andrew V. Trask | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Arthur John Argall, III | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Charles McCloud | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Christian GladdenSorensen | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | David I. Berl | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Elizabeth Weiswasser | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Jacob Hartman | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Kathryn Schleckser Kayali | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Priyata Patel At | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Rhochelle Krawetz | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Shaun Patrick Mahaffy | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Thomas S. Fletcher | Attorney | Counsel for Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Kellogg, Hansen, Todd, Figel & Frederick, PLLC | Law Firm | Representing Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Paul, Weiss, Rifkind, Wharton & Garrison LLP | Law Firm | Representing Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Williams & Connolly LLP | Law Firm | Representing Regeneron Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | William A. Rakoczy. | Attorney | Counsel for Mylan Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant law firm | Rakoczy, Molino, Mazzochi, Siwik LLP | Law Firm | Representing Mylan 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 ruling — ‘We have considered Regeneron’s remaining arguments and find them unpersuasive. For the foregoing reasons, we affirm. AFFIRMED.’ — is deliberately compact, consistent with a panel that found the lower court’s reasoning sufficient without requiring additional elaboration. The phrase ‘remaining arguments’ suggests some issues were already resolved or conceded prior to the written decision. Applying de novo review to claim construction and clear-error review to underlying facts, the court’s unqualified affirmance across 13 patents means no claim was narrowed, reversed, or remanded — a complete appellate victory for Regeneron.
US9222106B2 and 12 aflibercept patents — anti-VEGF biologics and manufacturing
The 13 patents at issue collectively protect Regeneron’s aflibercept platform — a VEGF-trap fusion protein marketed as Eylea for wet age-related macular degeneration and other angiogenic eye diseases. The portfolio spans the full development chain: upstream CHO cell-line engineering and integration site selection (US9816110B2), recombinant expression enhancement (US10415055B2, US10669594B2), manufacturing process control including chemically defined media and variant reduction (US11084865B2), quality analytics for contaminant detection (US9254338B2), and downstream formulation science for intravitreal delivery (US11253572B2, US10888601B2). Application dates across the portfolio range from 2013 to 2021, providing staggered expiry dates.
The strategic significance of this portfolio lies in its layered architecture. No single biosimilar developer can reach aflibercept’s clinical profile without engaging multiple layers of IP: the protein composition itself, the CHO manufacturing process, the analytical quality system, and the intravitreal formulation. This design makes a design-around commercially non-trivial and legally hazardous. Following Federal Circuit affirmance, the validated claim scope now sets a concrete standard against which biosimilar BLA submissions will be measured, with meaningful implications for Coherus, Outlook Therapeutics, and any other pipeline developer targeting the anti-VEGF retinal disease market.
Should you run an FTO against Regeneron’s affirmed aflibercept patent portfolio?
Any company currently developing, manufacturing, or commercialising an anti-VEGF biologic — particularly aflibercept biosimilars or next-generation VEGF-trap candidates — should treat this Federal Circuit affirmance as a mandatory trigger for a fresh FTO analysis. The 13 affirmed patents now carry heightened enforceability weight. Critically, the portfolio’s scope extends beyond the active molecule to CHO cell-line biology, manufacturing process parameters, contaminant detection methodology, and intravitreal formulation — meaning FTO analysis must cover your entire development and manufacturing workflow, not just the drug substance.
PatSnap Eureka’s FTO Search Agent can map your manufacturing process, formulation approach, and therapeutic use claims against all 13 affirmed Regeneron patents simultaneously, flagging overlap at the claim level. Eureka’s AI-powered claim comparison identifies whether your specific CHO host cell strategy, media composition, or intravitreal excipient profile falls within or outside the affirmed claim scope — enabling your regulatory and IP teams to make informed go/no-go decisions with documented evidence before BLA filing.
Run a freedom-to-operate analysis on US9222106B2 to assess your product’s exposure
Run FTO in Eureka →Similar Federal Circuit biosimilar and anti-VEGF patent appeals
Federal Circuit cases involving VEGF antagonist biologics, CHO manufacturing IP, and multi-defendant biosimilar patent infringement appeals similar to Regeneron v. Mylan.
What this case signals for the biopharmaceutical and biosimilar IP landscape
A seven-defendant coalition failed to dislodge a 13-patent biologics portfolio — the implications for anti-VEGF and broader biosimilar strategy are immediate.
Layered biologics patents are harder to invalidate collectively than in isolation
Seven well-resourced biosimilar developers — including Amgen, Sandoz, and Samsung Bioepis — could not collectively overcome Regeneron’s 13-patent portfolio at the Federal Circuit. This suggests that portfolio breadth covering manufacturing process, cell line, formulation, and therapeutic use creates compounding defensive strength that invalidation strategies targeting individual patents struggle to neutralise.
Biosimilar developers must pivot to USPTO IPR or design-around — litigation alone is insufficient
With the Federal Circuit avenue now closed, the remaining commercial path for these seven defendants requires either a Supreme Court certiorari petition (a high threshold), inter partes review at the USPTO on distinct prior art grounds, or product redesign to avoid the validated claims. Biosimilar programme leaders should audit their ANDA or BLA submissions against the specific claim scope affirmed in this case.
Regeneron v Mylan — key questions answered
The Federal Circuit affirmed the lower court’s ruling in full, upholding all 13 of Regeneron’s asserted patents covering aflibercept composition, CHO manufacturing, contaminant detection, and intravitreal formulation. The court found Regeneron’s remaining arguments unpersuasive and issued a clean affirmance on 14 March 2025, 171 days after the appeal was filed.
Regeneron asserted 13 patents: US9222106B2, US11084865B2, US9816110B2, US11253572B2, US10415055B2, US10669594B2, US10888601B2, US10130681B2, US10464992B2, US11066458B2, US9254338B2, US11306135B2, and US11104715B2. These cover anti-VEGF protein compositions, CHO integration sites, biological contaminant detection, enhanced expression regions, reduced-variant aflibercept manufacturing, VEGF antagonist therapeutic use, and intravitreal formulations.
The seven defendants were Mylan Pharmaceuticals, Amgen, Amgen USA, Biocon Biologics, Formycon AG, Celltrion, Samsung Bioepis, and Sandoz — all developing aflibercept biosimilars. The products at issue spanned the full aflibercept value chain: anti-VEGF protein compositions, CHO manufacturing processes, formulation for intravitreal administration, and analytical methods for the biologic.
Following affirmance, the standard appellate route at the Federal Circuit is exhausted. Defendants could petition the U.S. Supreme Court for certiorari, though this is granted only rarely. Alternatively, defendants may pursue inter partes review at the USPTO on distinct prior art grounds not previously raised, or develop design-around strategies that fall outside the validated claim scope. Settlement or licensing negotiations with Regeneron are also possible.
The affirmance binds the specific parties — Mylan, Amgen, Biocon, Celltrion, Samsung Bioepis, Sandoz, and Formycon — and is precedential as a Federal Circuit decision. Other developers not named in this action are not directly bound but should treat the affirmed claim constructions as authoritative guidance on the scope and validity of Regeneron’s 13 patents, making FTO analysis against the specific affirmed claims essential for any entity commercialising an anti-VEGF biologic in the U.S. market.
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