Federal Circuit Affirms Ruling Against Biosimilar Makers in Landmark Eylea® Patent Battle

In a significant victory for Regeneron Pharmaceuticals, the U.S. Court of Appeals for the Federal Circuit affirmed the lower court’s ruling in Mylan NV et al. v. Regeneron Pharmaceuticals, Inc. (Case No. 24-2009), closing the door on a coordinated biosimilar challenge to Regeneron’s foundational patent portfolio protecting Eylea® (aflibercept). The appeal, filed June 26, 2024, and resolved January 29, 2025 — a span of just 217 days — ended with a decisive affirmation, dismissing the biosimilar coalition’s arguments in full.

At stake were 13 patents spanning anti-VEGF protein manufacturing, CHO cell expression systems, formulation science, and ophthalmic drug delivery — a portfolio that underpins one of the world’s leading treatments for neovascular age-related macular degeneration (AMD) and other angiogenic eye disorders. For patent attorneys, IP professionals, and biopharmaceutical R&D teams, this case offers critical lessons in portfolio-based patent enforcement, biosimilar litigation strategy, and the durability of layered IP protection in the biologics space.

Case Overview

The Parties

Patents at Issue

This landmark case involved thirteen U.S. patents covering fundamental elements of aflibercept (Eylea®) and its manufacturing, spanning multiple technology domains:

• • US9222106B2 — Manufacturing & Expression (Anti-VEGF protein manufacturing)
• • US9816110B2 — Manufacturing & Expression (CHO cell expression systems)
• • US10415055B2 — Manufacturing & Expression (Chemically defined media)
• • US10669594B2 — Manufacturing & Expression (Biological contaminant detection)
• • US11084865B2 — Manufacturing & Expression (Enhanced expression)
• • US11104715B2 — Manufacturing & Expression (CHO cell integration sites)
• • US11306135B2 — Manufacturing & Expression (Reduced-variant aflibercept)
• • US10130681B2 — Formulation & Stability (Ophthalmic drug delivery)
• • US10464992B2 — Formulation & Stability (Enhanced stability regions)
• • US10888601B2 — Formulation & Stability (VEGF antagonist formulations)
• • US11066458B2 — Formulation & Stability (Intravitreal administration)
• • US9254338B2 — Therapeutic Use (Methods of treatment)
• • US11253572B2 — Therapeutic Use (Specific use parameters)

Litigation Timeline & Procedural History

The case arrived at the Federal Circuit as an appellate matter, meaning the consolidated biosimilar challengers had already litigated and lost at the district court level before escalating. The 217-day appellate resolution is notably efficient for Federal Circuit patent appeals, which frequently extend beyond 12 to 18 months — suggesting the appellate panel found the lower court’s reasoning well-grounded and the appellants’ arguments insufficiently novel to warrant extended briefing cycles or oral argument complexity.

The District of Columbia venue and Federal Circuit jurisdiction are standard for patent infringement appeals of this nature, ensuring consistent application of patent law doctrine across the biologics sector.

Key Dates

• Appeal Filed: June 26, 2024
• Court: Federal Circuit (D.C. Region)
• Appeal Resolved: January 29, 2025
• Duration: 217 days
• Basis of Termination: Appeal Dismissed / Affirmed

The Verdict & Legal Analysis

Outcome

The Federal Circuit issued a clean, unambiguous disposition: AFFIRMED. The appeal was dismissed, and Regeneron’s patent portfolio survived intact. No damages figures were disclosed in the available case data, consistent with the appellate posture — this was a validity and infringement affirmation, not a damages determination phase.

Verdict Cause Analysis

The case was classified as an Infringement Action, meaning the central dispute involved whether the biosimilar developers’ manufacturing processes, compositions, or methods infringed Regeneron’s valid patent claims. By affirming the lower court, the Federal Circuit endorsed the underlying claim construction, infringement findings, and validity determinations that protected Regeneron’s 13-patent portfolio.

Several strategic dimensions merit analysis:

• Breadth of Patent Portfolio: Regeneron’s enforcement did not rest on a single foundational patent. The 13-patent portfolio spanned upstream manufacturing (CHO integration sites, expression systems), downstream formulation (intravitreal stability, reduced variant production), and end-use therapeutic claims. This layered approach created multiple independent infringement vectors — a sophisticated prosecution strategy that made design-around exceptionally difficult for biosimilar developers.
• Coordinated Challenger Coalition: The assembly of seven biosimilar companies as co-plaintiffs-appellants reflects an increasingly common litigation tactic in biologics: pooling resources to challenge originator patents collectively, sharing discovery costs, and presenting a unified invalidity narrative. The Federal Circuit’s affirmation despite this coordinated challenge underscores the robustness of Regeneron’s prosecution history and claim drafting.
• Claim Construction Durability: An appellate affirmation typically signals that the district court’s claim construction — the judicial interpretation of what patent claims mean and cover — was well-reasoned and consistent with intrinsic evidence. For biosimilar litigants, a failed claim construction challenge at appeal is a significant setback, as it forecloses the primary pathway to non-infringement findings.

Legal Significance

This ruling carries precedential weight for the VEGF antagonist and broader biologics patent space. It reinforces that:

1. Multi-layered manufacturing and formulation patent portfolios can withstand coordinated invalidity challenges when prosecution is rigorous.
2. The Federal Circuit will affirm lower courts where claim construction aligns with patent specification and prosecution history.
3. Biosimilar interchangeability pathways under the BPCIA do not automatically overcome patent exclusivity when originator portfolios are strategically structured.

Industry & Competitive Implications

Strategic Takeaways

The Federal Circuit’s affirmation preserves Regeneron’s commercial exclusivity position in the aflibercept market at a pivotal moment. With global anti-VEGF therapy markets projected to remain among the highest-value segments in ophthalmology, the patent protection confirmed in this ruling has direct revenue implications worth billions of dollars annually.

For the biosimilar industry broadly, this outcome signals that originator companies with sophisticated IP strategies — particularly those who file continuation applications covering manufacturing improvements and formulation optimizations — can maintain durable barriers even against well-resourced challengers. The coordinated litigation approach by Mylan, Amgen, Samsung Bioepis, Biocon, FORMYCON, and Celltrion, while commercially rational, did not produce the patent clearance these developers required.

Licensing dynamics in the VEGF antagonist space may shift as a result. Biosimilar developers who cannot defeat Regeneron’s patents in litigation may pivot toward negotiated licensing arrangements — a trend increasingly common in the post-*Amgen v. Sanofi* biologics landscape. Companies evaluating pipeline investments in anti-VEGF biosimilars should factor this affirmation into risk-adjusted valuations and timeline modeling.

• For Patent Holders: Regeneron’s portfolio architecture — spanning protein science, cell biology, manufacturing chemistry, and clinical formulation — provides a replicable model. IP teams protecting blockbuster biologics should pursue claim diversity across the product lifecycle, from CHO cell expression through to final drug product stability.
• For Accused Infringers/Biosimilar Developers: The failure of a seven-company coalition to overcome 13 patents on appeal suggests that inter partes review (IPR) challenges at the PTAB, pursued earlier and more aggressively, may offer superior leverage compared to district court invalidity defenses. Post-grant proceedings allow prior art challenges on a preponderance standard before specialized administrative judges.
• For R&D Teams: Freedom-to-operate (FTO) analysis for any aflibercept biosimilar program must now account for the confirmed enforceability of all 13 patents. Development teams should assess whether process modifications — particularly in CHO cell line engineering, media composition, and intravitreal formulation parameters — can achieve genuine non-infringement without compromising product quality or regulatory approval pathways.