Mylan v. Regeneron (24-1965): Federal Circuit Affirms Aflibercept Biosimilar Injunction
A six-member biosimilar coalition led by Mylan NV failed to overturn a preliminary injunction protecting Regeneron’s aflibercept franchise across 13 patents. The Federal Circuit found no reversible error in the district court’s ruling in a case resolved in 223 days, keeping biosimilar market entry blocked.
Six-party biosimilar coalition fails to lift Regeneron’s aflibercept injunction at Federal Circuit
Filed June 20, 2024 at the Court of Appeals for the Federal Circuit, Case 24-1965 pitted a six-member biosimilar applicant coalition — Mylan NV, Amgen Inc., Biocon Biologics, FORMYCON AG, Celltrion Inc., Samsung Bioepis, and Amgen USA — against Regeneron Pharmaceuticals. The dispute centered on 13 US patents covering the VEGF antagonist aflibercept, its production processes in CHO cells, formulation for intravitreal administration, and related biological contaminant detection methods.
On January 29, 2025, the Federal Circuit issued its ruling affirming the district court’s grant of a preliminary injunction in Regeneron’s favor. The court explicitly addressed and rejected the remaining arguments advanced by the Samsung Bioepis-led coalition (‘SB’), finding them unpersuasive. The affirmance means the injunction blocking biosimilar market entry remains in force, and the appellants cannot re-litigate these arguments at the Federal Circuit level.
The 223-day resolution is notably swift for a Federal Circuit appeal, consistent with expedited handling of preliminary injunction appeals where commercial urgency is high. The case underscores the strength of Regeneron’s layered patent estate around aflibercept: with 13 patents spanning therapy, manufacturing, and formulation, the coalition faced an unusually broad IP barrier. What remains unknown from the public record is whether settlement negotiations are ongoing or whether the biosimilar applicants will pursue further inter partes review challenges.
Filing to Appeal Dismissed in 223 days
223 days — appeal resolved faster than the median Federal Circuit case (~18 months), suggesting a streamlined briefing schedule tied to the injunction’s urgency
Federal Circuit affirms: what the preliminary injunction ruling means for both parties
Affirmance means the lower court’s injunction stands intact
When the Federal Circuit affirms, it signals the appellate panel found no reversible error in the district court’s legal or factual analysis. In a preliminary injunction context, this means the lower court’s four-factor balancing — likelihood of success, irreparable harm, balance of equities, public interest — was applied correctly. The biosimilar applicants’ remaining arguments were expressly considered and rejected, not merely set aside on procedural grounds.
No reversible error foundRegeneron’s injunction survives — biosimilar entry remains blocked
The affirmance is a significant enforceability signal for Regeneron’s aflibercept portfolio. A preliminary injunction already implied the district court found a likelihood of success on the merits across at least some of the 13 patents. Federal Circuit affirmance raises the evidentiary bar for any future appellate challenge. Regeneron’s commercial exclusivity in the VEGF antagonist space, particularly for intravitreal indications, is strengthened by this outcome.
Patent exclusivity reinforcedCoalition’s Federal Circuit options exhausted at this stage
For Mylan, Amgen, Biocon, Samsung Bioepis, FORMYCON, and Celltrion, the affirmance forecloses re-argument of the rejected positions at the Federal Circuit level. Available paths forward may include petitioning the Supreme Court (certiorari), pursuing IPR or PGR proceedings against individual patents, or awaiting final merits adjudication at district court level. Each route carries cost and timeline implications that likely affect commercial biosimilar launch planning.
Appeal paths narrowedLayered biologics IP portfolios signal rising biosimilar entry barriers
This case illustrates the strategic value of multi-patent portfolio construction in biologics: 13 patents spanning therapy, CHO manufacturing, formulation, and detection methods created a litigation barrier that even a six-party coalition could not immediately clear on appeal. Biosimilar developers in the ophthalmology and VEGF antagonist space should anticipate heightened injunction risk when facing similarly layered originator estates and should prioritize early FTO analysis across process as well as composition patents.
Biosimilar entry risk elevatedFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Mylan, NV | Company | Biosimilar applicants consortium — challengers to Regeneron’s aflibercept patent estateSearch 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 — biopharmaceutical company holding 13 patents covering aflibercept VEGF antagonist products and processesSearch 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 verdict language — ‘we have considered SB’s remaining arguments and find them unpersuasive’ — is a full merits dismissal of the coalition’s appellate positions, not a procedural ruling. The phrase ‘for the foregoing reasons, we affirm’ confirms the panel applied the abuse-of-discretion standard typically governing preliminary injunction appeals and found the district court’s balancing of the four injunction factors legally sound. The explicit rejection of ‘remaining arguments’ suggests earlier arguments may have been addressed substantively in the opinion, and this closing statement resolves the residual issues. Regeneron emerges with a judicially validated injunction record that substantially strengthens its position in any subsequent merits proceedings.
US9222106B2 and 12 further patents — aflibercept VEGF antagonist biologics estate
The 13 patents at issue collectively cover the full lifecycle of aflibercept as a VEGF antagonist biologic: from the foundational therapeutic use in angiogenic eye disorders (US9222106B2, filed January 2013) through CHO cell integration and expression optimization, protein composition and manufacturing in chemically defined media, formulation for intravitreal administration, and contaminant detection. The portfolio spans application dates from 2013 to 2021, reflecting a multi-year layering strategy designed to extend patent coverage well beyond the original composition-of-matter expiry.
For competitors in the ophthalmology biologics space, this portfolio structure presents a formidable challenge: even parties who design around upstream VEGF antagonist claims face downstream manufacturing and formulation patents. The affirmance of the preliminary injunction against a six-party coalition suggests the district court found a credible likelihood of success on at least a substantial subset of these 13 patents. Companies developing anti-VEGF biosimilars — particularly those targeting ranibizumab or bevacizumab adjacencies — should monitor this portfolio closely as it sets a high bar for VEGF antagonist biosimilar market entry.
Should you run an FTO against Regeneron’s aflibercept patent estate?
Any company developing a biosimilar or biobetter targeting VEGF-mediated angiogenic eye disorders — including wet AMD, diabetic macular edema, or retinal vein occlusion — should treat Regeneron’s 13-patent estate as a primary FTO target. The estate covers not just the VEGF antagonist molecule but CHO manufacturing processes, chemically defined media formulations, and intravitreal delivery — meaning a standard composition FTO is insufficient. Process development teams, formulation scientists, and regulatory affairs leads all need visibility into this portfolio.
PatSnap Eureka’s FTO Search Agent enables R&D and IP teams to map their biosimilar candidate against each of the 13 patent families simultaneously, flagging claim-level overlap across manufacturing, formulation, and therapeutic use claims. Eureka can also track prosecution history and IPR filing activity against each patent, giving you early warning of validity challenges that may shift the competitive landscape before your IND filing.
Run a freedom-to-operate analysis on US9222106B2 to assess your product’s exposure
Run FTO in Eureka →Similar Federal Circuit biosimilar injunction appeals in VEGF antagonist litigation
These Federal Circuit cases involve preliminary injunction appeals in biologics and biosimilar VEGF antagonist or ophthalmology patent disputes, sharing key procedural and substantive features with Case 24-1965.
What this case signals for the biologics and biosimilar IP landscape
Regeneron’s 13-patent defense and Federal Circuit affirmance set a high-watermark precedent for VEGF antagonist biosimilar litigation strategy.
Multi-patent estates create disproportionate biosimilar injunction risk
The 13-patent portfolio here — spanning method, composition, manufacturing, and formulation claims — forced the coalition to invalidate or design around the entire estate to lift the injunction. Biosimilar developers should conduct pre-IND FTO audits against all patent layers, not just composition-of-matter claims, to assess injunction vulnerability before committing to development timelines.
Federal Circuit speed on injunction appeals signals commercial urgency premium
At 223 days, this appeal was resolved significantly faster than typical Federal Circuit timelines. Parties seeking to maintain or lift injunctions should expect accelerated briefing schedules and prepare commercially relevant expert evidence early. The urgency premium means that weak preliminary injunction records are difficult to rehabilitate at the appellate stage.
Mylan v Regeneron — key questions answered
The Federal Circuit affirmed the district court’s grant of a preliminary injunction in favor of Regeneron Pharmaceuticals. The court rejected all remaining arguments advanced by the biosimilar coalition (led by Samsung Bioepis) as unpersuasive, leaving the injunction blocking biosimilar aflibercept market entry intact as of January 29, 2025.
Thirteen US patents are asserted, including US9222106B2, US11084865B2, US9816110B2, US11253572B2, US10415055B2, US10669594B2, US10888601B2, US10130681B2, US10464992B2, US11066458B2, US9254338B2, US11306135B2, and US11104715B2. They cover VEGF antagonist therapy, aflibercept protein composition, CHO cell manufacturing, formulation for intravitreal use, and contaminant detection.
Affirmance means the Federal Circuit found no reversible error in the district court’s injunction analysis, including its finding of a likelihood of Regeneron’s success on the merits. The biosimilar applicants remain barred from launching their products while litigation continues. To lift the injunction, challengers would typically need to succeed at final merits trial or invalidate the relevant patents via IPR.
The coalition includes Mylan NV (lead plaintiff), Amgen Inc., Amgen USA Inc., Biocon Biologics Inc., FORMYCON AG, Celltrion Inc., and Samsung Bioepis Co. Ltd. The Federal Circuit opinion references ‘SB’s remaining arguments,’ suggesting Samsung Bioepis served as the primary appellate advocate for the coalition.
Available options include: (1) petitioning the Supreme Court for certiorari, though grant is rare in patent injunction matters; (2) filing IPR or PGR petitions against individual patents in the estate at the USPTO; (3) contesting infringement or validity at final merits trial in the district court; or (4) negotiating licensing arrangements with Regeneron. The public record does not disclose whether any of these steps are currently being pursued.
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